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Sample records for hertz stress-life exponent

  1. Relation Between Hertz Stress-Life Exponent, Ball-Race Conformity, and Ball Bearing Life

    Science.gov (United States)

    Zaretsky, Erwin V.; Poplawski, Joseph V.; Root, Lawrence E.

    2008-01-01

    ANSI/ABMA and ISO standards based on Lundberg-Palmgren bearing life theory are normalized for ball bearings having inner- and outerrace conformities of 52 percent (0.52) and made from pre-1940 bearing steel. The Lundberg-Palmgren theory incorporates an inverse 9th power relation between Hertz stress and fatigue life for ball bearings. The effect of race conformity on ball set life independent of race life is not incorporated into the Lundberg-Palmgren theory. In addition, post-1960 vacuum-processed bearing steel exhibits a 12th power relation between Hertz stress and life. The work reported extends the previous work of Zaretsky, Poplawski, and Root to calculate changes in bearing life--that includes the life of the ball set--caused by race conformity, Hertz stress-life exponent, ball bearing type and bearing series. The bearing fatigue life in actual application will usually be equal to or greater than that calculated using the ANSI/ABMA and ISO standards that incorporate the Lundberg-Palmgren theory. The relative fatigue life of an individual race is more sensitive to changes in race conformity for Hertz stress-life exponent n of 12 than where n = 9. However, when the effects are combined to predict actual bearing life for a specified set of conditions and bearing geometry, the predicted life of the bearing will be greater for a value of n = 12 than n = 9.

  2. Concerning Hertz' photoelectric effect

    OpenAIRE

    Vesely, S. L.; Vesely, A. A.

    2002-01-01

    Experimental evidence of the photoelectric effect goes back to H. Hertz. It occurred during the famous confirmation experiments of the Maxwellian theory. It is commonly held however that it cannot be explained in the framework of that theory. We are calling attention to some aspects linked with the interpretation of that effect on which, in our opinion, it is worthwhile reflecting.

  3. Lyapunov Exponents

    CERN Document Server

    Crauel, Hans; Eckmann, Jean-Pierre

    1991-01-01

    Since the predecessor to this volume (LNM 1186, Eds. L. Arnold, V. Wihstutz)appeared in 1986, significant progress has been made in the theory and applications of Lyapunov exponents - one of the key concepts of dynamical systems - and in particular, pronounced shifts towards nonlinear and infinite-dimensional systems and engineering applications are observable. This volume opens with an introductory survey article (Arnold/Crauel) followed by 26 original (fully refereed) research papers, some of which have in part survey character. From the Contents: L. Arnold, H. Crauel: Random Dynamical Systems.- I.Ya. Goldscheid: Lyapunov exponents and asymptotic behaviour of the product of random matrices.- Y. Peres: Analytic dependence of Lyapunov exponents on transition probabilities.- O. Knill: The upper Lyapunov exponent of Sl (2, R) cocycles:Discontinuity and the problem of positivity.- Yu.D. Latushkin, A.M. Stepin: Linear skew-product flows and semigroups of weighted composition operators.- P. Baxendale: Invariant me...

  4. HERTZ, A Submillimeter Polarimeter

    Science.gov (United States)

    Schleuning, D. A.; Dowell, C. D.; Hildebrand, R. H.; Platt, S. R.; Novak, G.

    1997-03-01

    We describe a 32 pixel polarimeter, Hertz, for use at the Caltech Submillimeter Observatory. We present polarization maps of the Orion molecular cloud (OMC-1) at 350 \\mum (46 detections) and 450 \\mum (19 detections) with 3\\sigma or better statistical significance. The 350 \\mum polarization ranges from 1.4 to 6.8% with a median value of 3.3%. The position angles are fairly uniform across the souce at an angle of \\sim30 degrees (east of north). We describe the design and performance characteristics of the polarimeter and discuss systematic effects due to telescope and instrumental polarization, atmospheric fluctuations, and reference beam flux. (SECTION: Astronomical Instrumentation)

  5. The Hertz's Method of Superpotential

    Science.gov (United States)

    Bleyer, U.; Treder, H.-J.

    The Method of HERTZ consists in the solution of the electromagnetic field equations by the help of a superpotential. We analyse the applicability of this method to more general field equations.Translated AbstractDie Hertzsche Methode der SuperpotentialeGemäß HERTZ können die Feldgleichungen der Elektrodynamik mit Hilfe eines Superpotentials gelöst werden. Wir untersuchen im folgenden die Anwendbarkeit dieser Methode auf allgemeinere Feldgleichungen.

  6. Lyapunov exponents

    CERN Document Server

    Barreira, Luís

    2017-01-01

    This book offers a self-contained introduction to the theory of Lyapunov exponents and its applications, mainly in connection with hyperbolicity, ergodic theory and multifractal analysis. It discusses the foundations and some of the main results and main techniques in the area, while also highlighting selected topics of current research interest. With the exception of a few basic results from ergodic theory and the thermodynamic formalism, all the results presented include detailed proofs. The book is intended for all researchers and graduate students specializing in dynamical systems who are looking for a comprehensive overview of the foundations of the theory and a sample of its applications.

  7. Reading Hertz's Own Dipole Theory

    Science.gov (United States)

    Anicin, B. A.

    2008-01-01

    It is well known that the discoverer of radio waves, Heinrich Hertz, was the first man to apply Maxwell's electrodynamic theory to a problem in radio wave propagation. In this paper, we scrutinize his near-field lines of force using computers and his theory. In one of his four figures, a feature was found which was not to be obtained by…

  8. Heinrich Hertz, the father of frequency.

    Science.gov (United States)

    Ramsay, Patricia Spieth

    2013-03-01

    Modernity stands on the shoulders of ancestors. Their historical foundations support and inspire our today. In 19th century Germany, Heinrich Rudolf Hertz was such a historical person. Hertz, a brilliant physicist, had the ability to integrate theoretical book knowledge with fundamental bench experimentation. Hertz's eclectic talents and research accomplishments ranged from drafting in architecture to meticulous manipulation of standard laboratory equipment often redesigned for his relentless curiosity (Buchwald 1994). He was the first to conclusively prove the existence of electromagnetic waves with precise experimental procedures and instrumentation he engineered to generate and detect waves (radio pulses) across space. His touchstone research verified Maxwell's theory and proved that all forms of electromagnetic radiation are propagated as waves at a finite velocity--the speed of light (Heinrich Hertz 2012). In recognition of his pivotal discoveries, Hertz's name is the universal synonym for frequency. Categorizing electroencephalographic (EEG) patterns by frequency is the primary emphasis of an EEG recording. The distribution of frequencies, amplitude, and polarity of electrocerebral potentials as recorded on the computer screen and/or graph paper result from numerous electrical fields of neuronal dipoles. Hertz's images drawn as the paper dipole remain the standard method for describing electrocerebral dipoles and the electrical fields of epileptiform activity recorded on a patient's electroencephalograph. Hertz's intended and inadvertent discoveries became the launch pad for numerous medical and media technologies. His former student Philipp Lenard won the 1905 Nobel Prize for Physics when he developed a version of the cathode tube and studied penetration by x-rays based on Herts'z cathode ray experiments in 1892. Additionally, Hertz did not pursure his ancillary discovery of the photoelectric effect in 1887. Albert Einstein would later explain features of

  9. ELECTION - A STRESSFUL LIFE EVENT

    OpenAIRE

    Gautam, Shiv; Aggarwal, Rajeev; Sharma, Himanshu

    1997-01-01

    54 patients who sought consultation at this centre after developing psychiatric illness following local panchayat elections in Rajasthan were studied. The study aims to find out whether election is a stressful life event, relationship of socio-demographic characteristics, role of process of election, and nature of psychiatric illness as related to election stress. This group was compared to general psychiatric patients randomly selected from the same hospital, with or without other stressful ...

  10. The Geometric Aspects of Hertz's Prinzipien der Mechanik

    DEFF Research Database (Denmark)

    Lützen, Jesper

    2008-01-01

    Hertz' posthumt udgivne være Prinzipien der Mechanik er berømt for sin filosofiske indledning og for at undgå kraftbegrebet, som basalt begreb. I denne artikel lægger jeg hovedvægten på et tredje karakteristisk træk ved Hertz' mekanik, nemlig dens geometriske form. Hertz besluttede at han ville...... understøttede hinanden gensidigt. I artiklen forklares hvordan Hertz' geometri for punktsystemer fungerer, og det analyseres hvordan den virker sammen med det fysiske indhold af Hertz's mekanik. Hertz' geometrisering af mekanikken sammenlignes med de tidligere forsøg af matematikere bl.a. Lipschitz som var...... Hertz' kollega i Bonn. Endelig diskuteres det hvordan Hertz på den ene side kunne indføre sin højdimensionale ikke-euklidiske geometri på faserummet, og på den anden side fastholde at rummet a priori er euklidisk og tredimensionalt....

  11. Gustav-Hertz-Prize for CERN Physicist

    CERN Multimedia

    2004-01-01

    Klaus Blaum, of GSI Darmstadt and project leader of the ISOLTRAP experiment at CERN, will receive the 2004 Gustav-Hertz-Prize for his outstanding work on the mass determination of unstable atomic nuclei. Blaum extended the measuring capability of the ISOLTRAP experiment at the ISOLDE facility, which studies short-lived isotopes, by installing a source of carbon clusters. Using these carbon clusters as mass reference allows researchers to obtain higher-precision and absolute atomic mass measurements which are important to understand the weak interaction and the synthesis of chemical elements. The Gustav-Hertz-Prize is awarded to outstanding young physicists and is endowed with 7500 euro. It will be awarded at the Spring Conference of the German Physical Society in Munich on 24 March.

  12. Fluctuations in Hertz chains at equilibrium.

    Science.gov (United States)

    Przedborski, Michelle; Sen, Surajit; Harroun, Thad A

    2017-03-01

    We examine the long-term behavior of nonintegrable, energy-conserved, one-dimensional systems of macroscopic grains interacting via a contact-only generalized Hertz potential and held between stationary walls. Such systems can be set up to have no phononic background excitation and represent examples of a sonic vacuum. Existing dynamical studies showed the absence of energy equipartitioning in such systems, hence their long-term dynamics was described as quasiequilibrium. Here we show that these systems do in fact reach thermal equilibrium at sufficiently long times, as indicated by the calculated heat capacity. As a by-product, we show how fluctuations of system quantities, and thus the distribution functions, are influenced by the Hertz potential. In particular, the variance of the system's kinetic energy probability density function is reduced by a factor related to the contact potential.

  13. SSME main injector 4000 Hertz phenomenon

    Science.gov (United States)

    Johnston, G. D.

    1986-01-01

    Several Space Shuttle Main Engines (SSME) have experienced very high acceleration responses measured in the main injector of the powerhead during static firings. Data from previous hot fire SSME tests relating to the 4000 hertz phenomenon were reviewed to provide a better understanding of the nature of this structural response. The objective was to technically understand the way this phenomenon works, recommend a fix and test the fix.

  14. Quantum critical Hall exponents

    CERN Document Server

    Lütken, C A

    2014-01-01

    We investigate a finite size "double scaling" hypothesis using data from an experiment on a quantum Hall system with short range disorder [1-3]. For Hall bars of width w at temperature T the scaling form is w(-mu)T(-kappa), where the critical exponent mu approximate to 0.23 we extract from the data is comparable to the multi-fractal exponent alpha(0) - 2 obtained from the Chalker-Coddington (CC) model [4]. We also use the data to find the approximate location (in the resistivity plane) of seven quantum critical points, all of which closely agree with the predictions derived long ago from the modular symmetry of a toroidal sigma-model with m matter fields [5]. The value nu(8) = 2.60513 ... of the localisation exponent obtained from the m = 8 model is in excellent agreement with the best available numerical value nu(num) = 2.607 +/- 0.004 derived from the CC-model [6]. Existing experimental data appear to favour the m = 9 model, suggesting that the quantum Hall system is not in the same universality class as th...

  15. Geometrizing configurations. Heinrich Hertz and his mathematical precursors

    DEFF Research Database (Denmark)

    Lützen, Jesper

    1999-01-01

    A comparison between the methods used by Heinrich hertz and his mathematician precursors such as Liouville, Lipschitz and Darboux in order to apply differential geometry in mechanics......A comparison between the methods used by Heinrich hertz and his mathematician precursors such as Liouville, Lipschitz and Darboux in order to apply differential geometry in mechanics...

  16. The Creation of Scientific Effects Heinrich Hertz and Electric Waves

    CERN Document Server

    Buchwald, Jed Z

    1994-01-01

    This book is an attempt to reconstitute the tacit knowledge—the shared, unwritten assumptions, values, and understandings—that shapes the work of science. Jed Z. Buchwald uses as his focus the social and intellectual world of nineteenth-century German physics. Drawing on the lab notes, published papers, and unpublished manuscripts of Heinrich Hertz, Buchwald recreates Hertz's 1887 invention of a device that produced electromagnetic waves in wires. The invention itself was serendipitous and the device was quickly transformed, but Hertz's early experiments led to major innovations in electrodyna

  17. Henry Rudolf Hertz (the 160th anniversary of his birth

    Directory of Open Access Journals (Sweden)

    V. P. Samokhin

    2017-01-01

    Full Text Available A brief overview of the main achievements of Heinrich Hertz, an outstanding German physicist, has been shown to prove to the whole world the existence of electromagnetic waves. Biographical information and details of Hertz's education, his work in Hermann Helmholtz's laboratory, as well as interesting facts from his life and work are given. These include the unique experimental work performed by Hertz, a professor at the Higher Technical School in Karlsruhe, using the emitter of electromagnetic waves - the "Hertz Vibrator" - and their own design receiver. Along with James Maxwell and Oliver Heaviside, Hertz can be considered the founder of electrodynamics: he received electromagnetic waves predicted by Maxwell's theory, showed their identity with light waves and gave a classical calculation of the electromagnetic radiation of the simplest vibrator. Hertz's discoveries formed the basis for the theory of radiation of radio waves and methods for calculating antennas, and became the basis for the birth of the era of wireless communications, radio and television.

  18. Scaling exponents of star polymers

    OpenAIRE

    von Ferber, Christian; Holovatch, Yurij

    2002-01-01

    We review recent results of the field theoretical renormalization group analysis on the scaling properties of star polymers. We give a brief account of how the numerical values of the exponents governing the scaling of star polymers were obtained as well as provide some examples of the phenomena governed by these exponents. In particular we treat the interaction between star polymers in a good solvent, the Brownian motion near absorbing polymers, and diffusion-controlled reactions involving p...

  19. A Mechanical Image: Heinrich Hertz's Principles of Mechanics

    DEFF Research Database (Denmark)

    Lützen, Jesper

    2006-01-01

    Heinrich Hertz's bog Die Prinzipien der Mechanik in neuem Zusammenhange dargestellt var nyskabende inden for både fysik, matematik og filosofi. I fysik lagde den det første fundament til en fysik, som undgår kraftbegrebet som et basalt begreb; i matematik præsenterede den en ny geometrisering af...... mekanikken i termer af den Riemannske geometri; og i filosofi præsenterede den en radikal ny teori om de mentale billeder vi kan danne os af naturen. I denne artikel analyseres hvordan Hertz' interesse i og arbejde med mekanikken og billedteorien voksede naturligt ud af hans tidligere forskning inden...... for fysikken og hans epistemologiske refleksioner over denne forskning. Derved illustreres den frugtbare vekselvirkning mellem de fysiske og filosofiske aspekter af Hertz' mekanik...

  20. Saul Hertz, MD, and the birth of radionuclide therapy.

    Science.gov (United States)

    Fahey, Frederic H; Grant, Frederick D; Thrall, James H

    2017-12-01

    The year, 2016, marked the 75th anniversary of Dr. Saul Hertz first using radioiodine to treat a patient with thyroid disease. In November of 1936, a luncheon was held of the faculty of Harvard Medical School where Karl Compton, PhD, president of the Massachusetts Institute of Technology was invited to give a presentation entitled "What Physics Can Do for Biology and Medicine." Saul Hertz who attended the luncheon spontaneously asked the very pertinent question that perhaps changed the course of treatment of thyroid disease, "Could iodine be made radioactive artificially?" We review the events leading up to the asking of this question, the preclinical investigations by Dr. Hertz and his colleague Arthur Roberts prior to the treatment of the first patient and what occurred in the years following this landmark event. This commentary seeks to set the record straight to the sequence of events leading to the first radioiodine therapy, so that those involved can be recognized with due credit.

  1. Virtually Exploring A Pillar Of Experimental Physics: The Hertz Experiment

    Science.gov (United States)

    Bonanno, A.; Sapia, P.; Camarca, M.; Oliva, A.

    2008-05-01

    In the present work we report on the implementation and early assessment of a multimedia learning object, developed using the Java programming language, which also integrates in a creative way some internet freely available educational resources, intended to support the teaching/learning process of the historical Hertz experiment.

  2. Optical and Electrical Sensor Busses for the Heinrich Hertz Satellite

    Science.gov (United States)

    Heyer, Heinz-Voker; Zeh, Thomas; Reutlinger, Arnd; Kammer, Susanne; Voigt, Siegfried

    2010-08-01

    Germany is planning the geostationary communication satellite Heinrich Hertz. The used platform will be the Small Geo platform of OHB. Phase A for this satellite has been performed successfully and two sensor busses in addition to the conventional harness have been selected for housekeeping measurement. *Sensor bus (wire related) *Optical bus (fiber related). The satellite will be launched in 2014. The payload will be a newly developed telecommunication equipment for in-orbit demonstration.

  3. Stressful life events, vulnerable to stress and depression among ...

    African Journals Online (AJOL)

    The present study was carried out to observe the difference between male and female Eritrean students on the basis of stressful life events, vulnerable to stress and depression. Stressful life Events Questionnaire, Vulnerable to Stress Instrument and Beck Depression Scale were administered to gather information. The data ...

  4. Suicide in Relation to the Experience of Stressful Life Events

    DEFF Research Database (Denmark)

    Fjeldsted, Rita; Teasdale, Thomas William; Jensen, Martin

    2016-01-01

    Stressful life events have been associated with high risk of suicidal behavior. The aim of this study was to examine whether persons who died by suicide in Denmark had more frequently been exposed to stressful life events, specifically divorce, death of a close relative, exposure to violence...

  5. Stressful life events and incident metabolic syndrome : The Hoorn study

    NARCIS (Netherlands)

    Rutters, F.; Pilz, S.; Koopman, A.D.; Rauh, S.P.; Pouwer, F.; Stehouwer, C.D.; Elders, P.J.; Nijpels, G.; Dekker, J.M.

    2015-01-01

    Stressful life events are associated with the metabolic syndrome in cross-sectional studies, but prospective studies addressing this issue are rare and limited. We therefore evaluated whether the number of stressful life events is associated with incident metabolic syndrome. We assessed the

  6. Stressful life events and alcohol use among university students in ...

    African Journals Online (AJOL)

    Stressful life events are known to be associated with substance use, especially among young adults. In this study, the association between stressful life events and alcohol use among young adults pursuing university education in a university in Botswana was studied. A total of 312 young adults participated in the study ...

  7. Personality, Stressful Life Events, and Treatment Response in Major Depression

    Science.gov (United States)

    Bulmash, Eric; Harkness, Kate L.; Stewart, Jeremy G.; Bagby, R. Michael

    2009-01-01

    The current study examined whether the personality traits of self-criticism or dependency moderated the effect of stressful life events on treatment response. Depressed outpatients (N = 113) were randomized to 16 weeks of cognitive-behavioral therapy, interpersonal psychotherapy, or antidepressant medication (ADM). Stressful life events were…

  8. Stressful life experiences and attachment in adolescence

    Directory of Open Access Journals (Sweden)

    Mihić Ivana

    2007-01-01

    Full Text Available The research presented in this paper aimed to explore relations between stressful life experiences and attachment in adolescence. The sample included 279 adolescents of both sexes, who were students of first two years at the University of Novi Sad. Attachment styles were assessed by RQ (Relationship Questionnaire, Bartolomew & Horowitz, 1991, and stressful experiences by Risk Scale (Grossman et al., 1990. The average score on the Risk scale indicated that participants had relatively small number of stressful events; but majority had at least two stressful experiences. The most frequent event was loss of family member (61,2% of participants and traffic accident (40,6% of participants. Participants with secure and insecure attachment styles had similar number of stressful experiences in their lives. Difference between these groups was significant only in the case stressors that origin from the characteristics of the family and intrafamilial relations, which was more frequent experience in participants with insecure attachment styles. However, the results showed that stressful experiences may have negative influence on security of attachment, i.e. on positivity of model of self. The highest and statistically significant contribution was made by separation from family and by family characteristics. The results are discussed in context of attachment theory and previous research data on effects of stressful and traumatic events on security of attachment.

  9. Stressful life events in older bipolar patients.

    Science.gov (United States)

    Beyer, John L; Kuchibhatla, Maragatha; Cassidy, Frederick; Krishnan, K Ranga R

    2008-12-01

    Theories about the impact of stressful life events (SLE) in bipolar disorder have focused on their role early in the disease. Few studies have examined SLE in older bipolar patients. We wanted to assess the impact of SLE in late life bipolar disorder We evaluated negative SLE experienced by older bipolar subjects compared with younger bipolar subjects and older controls for number, type, and their association with phase of illness, age of onset, and previous episodes. Both younger and older bipolar subjects have more SLE than similarly aged controls. There was no significant difference in the number of stressors that younger and older bipolar subjects experienced, based on mood state, previous episodes, or age-of-onset. Both older and younger depressed bipolar subjects reported more SLE in the previous 12 months compared with those in a manic state. Negative SLE are much more prevalent in bipolar patients compared with age-matched controls, and continue to be frequent in later life. (c) 2008 John Wiley & Sons, Ltd.

  10. Passive Scalar Scaling Exponents and Realizability

    CERN Document Server

    Kraichnan, R H

    1997-01-01

    Realizability of the statistics of a temperature field passively advected by a rapidly-varying velocity field is a constraint on the possible inertial-range scaling exponents. Further restrictions on exponents follow if the dissipation conditioned on temperature difference is a smooth, monotonic function. Realizability of the so-called linear ansatz is verified numerically, and the form of the associated probability distribution function is computed. Monotonicity of the conditional mean of dissipation can be sensitive to small changes in the exponents.

  11. Hertz and the Discovery of Radio Waves and the Photoelectric Effect.

    Science.gov (United States)

    Spradley, Joseph L.

    1988-01-01

    Describes the discoveries by Hertz historically, such as photoelectric effect, radio waves, their impact on modern physics and some applications. Presents several diagrams and two chronological tables. (YP)

  12. Prediction errors and local Lyapunov exponents

    CERN Document Server

    Kennel, M B; Sidorowich, J J S; Matthew B Kennel; Henry D I Abarbanel

    1994-01-01

    It is frequently asserted that in a chaotic system two initially close points will separate at an exponential rate governed by the largest global Lyapunov exponent. Local Lyapunov exponents, however, are more directly relevant to predictability. The difference between the local and global Lyapunov exponents, the large variations of local exponents over an attractor, and the saturation of error growth near the size of the attractor---all result in non-exponential scalings in errors at both short and long prediction times, sometimes even obscuring evidence of exponential growth. Failure to observe exponential error scaling cannot rule out deterministic chaos as an explanation. We demonstrate a simple model that quantitatively predicts observed error scaling from the local Lyapunov exponents, for both short and surprisingly long times. We comment on the relevance to atmospheric predictability as studied in the meteorological literature.

  13. The Hertz/VPM Polarimeter: Design and First Light Observations

    Science.gov (United States)

    Krejny, Megan; Chuss, David; d'Aubigny, Christian Drouet; Golish, Dathon; Houde, Martin; Hui, Howard; Kulesa, Craig; Loewenstein, Robert F.; Moseley, Harvey; Novak, Giles; hide

    2008-01-01

    We present first results of Hertz/VPM, the first submillimeter polarimeter employing the dual Variable-delay Polarization Modulator (dual-VPM). This device differs from previously used polarization modulators in that it, operates in translation rather than mechanical rotation. We discuss the basic theory behind this device, and its potential advantages over the commonly used half wave plate (HFVP). The dual-VPM was tested both at the Submillimeter Telescope Observatory (SMTO) and in the lab. In each case we present a detailed description of the setup. We discovered nonideal behavior in the system. This is at least in part due to properties of the VPM wire grids (diameter, spacing) employed in our experiment. Despite this, we found that the dual-VPM system is robust, operating with high efficiency and low instrumental polarization. This device is well suited for air and space-borne applications.

  14. Lyapunov Exponents as Functions of a Parameter

    Science.gov (United States)

    Millionshchikov, V. M.

    1990-02-01

    The author proves the typical nature, in the sense of Baire category, of the upper semicontinuity of the Lyapunov exponents of a family of endomorphisms of a metrized vector bundle, considered as a function of a parameter on which a point of the base of this bundle continuously depends. It is proved that the Lyapunov exponents, as functions of this parameter, belong to the second Baire class. An application of these abstract theorems to the Lyapunov exponents of nonlinear systems of differential equations continuously depending on a parameter is given. Bibliography: 14 titles.

  15. 77 FR 70440 - Hertz Global Holdings, Inc.; Analysis of Agreement Containing Consent Orders To Aid Public Comment

    Science.gov (United States)

    2012-11-26

    ... Hertz Global Holdings, Inc.; Analysis of Agreement Containing Consent Orders To Aid Public Comment... SUPPLEMENTARY INFORMATION section below. Write ``Hertz, File No. 101 0137'' on your comment and file your... December 17, 2012. Write ``Hertz, File No. 101 0137'' on your comment. Your comment--including your name...

  16. Stressful Life Events and Irrational Beliefs as Predictors of ...

    African Journals Online (AJOL)

    Literature reveals that stressful life events and irrational beliefs are negatively correlated with Psychological Wellbeing characterized with negative indicators, such as, anxiety, depression. Does similar relationship is evident referring to positive indicators of Psychological Wellbeing with a sample of early adolescent girls?

  17. Sibling Socialization: The Effects of Stressful Life Events and Experiences

    Science.gov (United States)

    Conger, Katherine J.; Stocker, Clare; McGuire, Shirley

    2009-01-01

    Stressful life events and experiences may disrupt the typical day-to-day interactions between sisters and brothers that provide the foundation of sibling socialization. This chapter examines four experiences that may affect patterns of sibling interaction: parental marital conflict, parental divorce and remarriage, foster care placement, and a…

  18. Stressful Life Events in Children With Functional Defecation Disorders.

    Science.gov (United States)

    Philips, Elise M; Peeters, Babette; Teeuw, Arianne H; Leenders, Arnold G E; Boluyt, Nicole; Brilleslijper-Kater, Sonja N; Benninga, Marc A

    2015-10-01

    The aim of the study was to determine the prevalence of stressful life events including (sexual) abuse in children with functional defecation disorders by performing a systematic review. We searched MEDLINE, EMBASE, and PsycINFO for cohort, case-control and cross-sectional studies investigating the prevalence of stressful life events, including (sexual) abuse in children with functional defecation disorders. The search yielded 946 articles, of which 8 were included with data from 654 children with functional constipation and 1931 children with (constipation-associated) fecal incontinence (FI). Overall, children with functional defecation disorders had been significantly more exposed to stressful life events than healthy children, with prevalence rates ranging from 1.6% to 90.9%. Being bullied, being a relational victim, interruption of toilet training, punishment by parents during toilet training, and hospitalization were significantly related to FI, whereas separation from the best friend, failure in an examination, severe illness in a close family member, loss of job by a parent, frequent punishment, and living in a war-affected area were significantly related to constipation. Only 1 study measured the prevalence of child abuse, which reported a significantly higher prevalence of child (sexual) abuse in children with FI compared with controls. The prevalence of stressful life events, including (sexual) abuse is significantly higher in children with functional defecation disorders compared with healthy children. To gain more insight into the true prevalence of child (sexual) abuse in children with functional defecation disorders, more studies are clearly needed.

  19. Stressful Life Events in Children With Functional Defecation Disorders

    NARCIS (Netherlands)

    Philips, Elise M.; Peeters, Babette; Teeuw, Arianne H.; Leenders, Arnold G. E.; Boluyt, Nicole; Brilleslijper-Kater, Sonja N.; Benninga, Marc A.

    2015-01-01

    The aim of the study was to determine the prevalence of stressful life events including (sexual) abuse in children with functional defecation disorders by performing a systematic review. We searched MEDLINE, EMBASE, and PsycINFO for cohort, case-control and cross-sectional studies investigating the

  20. Hertz vector and current distribution of microstrip spiral antenna in biological stratified media

    Science.gov (United States)

    Gao, Li; Xiang, Xun-Xian

    1993-09-01

    The Hertz vectors of the horizontal electric dipole in stratified biological media are derived from spectral domain wave matrii method. By using the Fourier-Bessel transformation we have obtained the solution of the hertz vectors in space domain. The electric field tangential to the microstrip antenna arm is derived by using the relationship between the hertz vectors and the electric field. In order to get the current distribution of the antenna arm the moment method is used. We have also analysed the Sommerfeld-type integrals which emerged in the process of finding the solution. It is important to find the current distribution for determining the parameters of antenna and finding the power deposition in biological media. l. TIIE hERTZ VECTORS OF HORIZONTAL ELECTRIC DIPOLE IN BIOLOGICAL STRATIFIED MEDIA The hertz vectors of electric dipole can be derived by using the spectral domain transmission coefficient method'' while the wave matrix method is useful to dealing with the reflection and transmission of the electromagnetic wave in stratified media2 the wave propagation inwhich ithas been studied''_ ''. The structurQ analysed in this paper is shown in Fig. 1. The Hertz vectors of electric dipole in biological stratified media are determined by using the wave matrix method. In Fig. I plane f is the nominal field plane and the source plane coincides with the interface B. At the interface B when you look in the 4 z

  1. Explicit predictability and dispersion scaling exponents in fully developed turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, Francois G. [CNRS, UMR 8013 ELICO, Wimereux Marine Station, University of Lille 1, 28 av. Foch, 62930 Wimereux (France)]. E-mail: francois.schmitt@univ-lille1.fr

    2005-07-25

    We apply a simple method to provide explicit expressions for different scaling exponents in intermittent fully developed turbulence, that before were only given through a Legendre transform. This includes predictability exponents for infinitesimal and noninfinitesimal perturbations, Lagrangian velocity exponents, and dispersion exponents. We obtain also new results concerning inverse statistics corresponding to exit-time moments.

  2. Stressful Life Events: Their Relationships with Coronary Heart Disease.

    Science.gov (United States)

    1983-09-01

    found * "asthma, rheumatoid arthritis , ulcerative colitis, and cancer...involve immunological factors that were unsuspected 25 years ago" (Bowers...as t. well as the development of thyroid malfunction, rheumatoid arthritis and asthma are directly related to excessive levels of stress. In addition...Mueller, D. P., Edwards, 0. W., & Yarvis, R. M. Stressful life events and psychiatric symptomatology : Change or undesirability? Journal of Health and

  3. Stressful life events as a link between problems in nonverbal communication and recurrence of depression

    NARCIS (Netherlands)

    Bos, Elisabeth H.; Bouhuys, Antoinette L.; Geerts, Eirwin; van Os, Titus W. D. P.; Ormel, Johan

    Background.- Interpersonal difficulties and stressful life events are important etiological factors in (recurrence of) depression. This study examines whether stressful life events mediate the influence of problems in nonverbal communication on recurrence of depression. Methods.- We registered

  4. A Sub-Hertz, Low-Frequency Vibration Isolation Platform

    Science.gov (United States)

    Ortiz, Gerardo, G.; Farr, William H.; Sannibale, Virginio

    2011-01-01

    One of the major technical problems deep-space optical communication (DSOC) systems need to solve is the isolation of the optical terminal from vibrations produced by the spacecraft navigational control system and by the moving parts of onboard instruments. Even under these vibration perturbations, the DSOC transceivers (telescopes) need to be pointed l000 fs of times more accurately than an RF communication system (parabolic antennas). Mechanical resonators have been extensively used to provide vibration isolation for groundbased, airborne, and spaceborne payloads. The effectiveness of these isolation systems is determined mainly by the ability of designing a mechanical oscillator with the lowest possible resonant frequency. The Low-Frequency Vibration Isolation Platform (LFVIP), developed during this effort, aims to reduce the resonant frequency of the mechanical oscillators into the sub-Hertz region in order to maximize the passive isolation afforded by the 40 dB/decade roll-off response of the resonator. The LFVIP also provides tip/tilt functionality for acquisition and tracking of a beacon signal. An active control system is used for platform positioning and for dampening of the mechanical oscillator. The basic idea in the design of the isolation platform is to use a passive isolation strut with an approximately equal to 100-mHz resonance frequency. This will extend the isolation range to lower frequencies. The harmonic oscillator is a second-order lowpass filter for mechanical disturbances. The resonance quality depends on the dissipation mechanisms, which are mainly hysteretic because of the low resonant frequency and the absence of any viscous medium. The LFVIP system is configured using the well-established Stewart Platform, which consists of a top platform connected to a base with six extensible struts (see figure). The struts are attached to the base and to the platform via universal joints, which permit the extension and contraction of the struts. The

  5. Experimental evaluation of a volts-per-hertz reference circuit for the isotope Brayton system

    Science.gov (United States)

    Wimmer, H. L.

    1972-01-01

    In Brayton-cycle power systems, the speed decreases rapidly with overload. If the voltage decreases linearly with speed (frequency), the power decreases as the square of the voltage. This makes the system more tolerant of overloads. A volts-per-hertz reference circuit, consisting of a volts-per-hertz sensor and a voltage limiter, was designed and fabricated. This reference circuit was incorporated in an existing voltage regulator to control a turbine-driven alternator. Test results show that the control does function to reduce voltage at speeds below the rated speed and that it performed successfully during transients.

  6. Lexical exponents of hypothetical modality in Polish and Lithuanian

    OpenAIRE

    Roman Roszko

    2015-01-01

    Lexical exponents of hypothetical modality in Polish and Lithuanian The article focuses on the lexical exponents of hypothetical modality in Polish and Lithuanian. The purpose for comparing and contrasting the lexical exponents of hypothetical modality is not only to identify all the lexemes in both languages but also find the answer to the following question: whether the morphological exponents of hypothetical modality (so-called modus relativus) familiar to the Lithuanian language have/...

  7. A Matter of Matter or a Matter of Space? Heinrich Hertz's Image of Mass in his Prinzipien der Mechanik

    DEFF Research Database (Denmark)

    Lützen, Jesper

    1999-01-01

    It is argued that Hertz introduced Massenteilchen in his Principles of Mechanics because they allowed him to deduce the line element of his differential geometric formalism......It is argued that Hertz introduced Massenteilchen in his Principles of Mechanics because they allowed him to deduce the line element of his differential geometric formalism...

  8. Nonlinearity exponents in lightly doped conducting polymers

    Science.gov (United States)

    Talukdar, D.; Nandi, U. N.; Bardhan, K. K.; Bof Bufon, C. C.; Heinzel, T.; de, A.; Mukherjee, C. D.

    2011-08-01

    The I-V characteristics of four conducting polymer systems such as doped polypyrrole, poly(3,4-ethylenedioxythiophene), polydiacetylene, and polyaniline in as many physical forms have been investigated at different temperatures, quenched disorder, and magnetic fields. Transport data clearly show the existence of a single electric-field scale in each system. Based upon this observation, a phenomenological scaling analysis is performed, leading to the extraction of a numerical value for a nonlinearity exponent called xM which serves to characterize a set of I-V curves. The conductivity starts deviating from an Ohmic value σ0 above an onset electric field Fo which scales according to Fo˜σ0xM. The electric-field-dependent data are shown to be described by the multistep tunneling model of Glazman-Matveev [JETP 67, 1276 (1988)] in a near-perfect manner over nine orders of magnitude in conductivity and five orders of magnitude in electric field. Furthermore, xM is found to possess both positive and negative values lying between -1/2 and 3/4. There is no theory at present for this exponent. Some issues concerning applicability of the Glatzman-Matveev model are discussed.

  9. Deficit or creativity: Cesare Lombroso, Robert Hertz, and the meanings of left-handedness.

    Science.gov (United States)

    Kushner, Howard I

    2013-01-01

    In the first decade of the twentieth century two influential researchers attempted to explain the origin and impact of left-handedness in human history. The first, the Turin physician Cesare Lombroso, often referred to as the father of modern criminology, was nearing the end of his long distinguished career. Lombroso tied left-handedness to criminality, insanity, and feeble mindedness. According to Lombroso, these groups shared biological regressions to primitive mentalities that could not be reversed by education or training. The second, French sociologist Robert Hertz, was at the beginning of a career cut short by his death in combat during the First World War. Hertz challenged Lombroso's claims, insisting that the predominance of right-handedness, whatever its biological substrate, was ultimately a cultural artefact driven by a primitive human urge to make sense of the world by dividing it into binary oppositions in which the right was viewed as sacred and the left as profane. Ending discrimination against left-handedness would, according to Hertz, unleash access to both hands and thus both hemispheres. The results, he insisted, would allow repressed talents and creativity to flourish. The conflicting views of Lombroso and Hertz have informed investigations of the causes and consequences of left-handedness until today. While the language of the debate has been reframed in current scientific discourses, left-handedness continues to be portrayed in the contradictory ways first elaborated by Lombroso and Hertz more than a century ago as either the cause of a variety of learning disabilities or as the key that can unlock creativity and talent. The debate also exposed the extent to which other cultural concerns, particularly anti-Semitism, informed theories of handedness.

  10. Stressful life events and psychological dysfunction in complex regional pain syndrome type I

    NARCIS (Netherlands)

    Geertzen, JHB; de Bruijn-Kofman, AT; de Bruijn, HP; van de Wiel, HBM; Dijkstra, PU

    Objective: To determine to what extent stressful life events and psychological dysfunction play a role in the pathogenesis of Complex Regional Pain Syndrome type I (CRPS). Design: A comparative study between a CRPS group and a control group. Stressful life events and psychological dysfunction

  11. Phase noise characterization of sub-hertz linewidth lasers via digital cross correlation.

    Science.gov (United States)

    Xie, Xiaopeng; Bouchand, Romain; Nicolodi, Daniele; Lours, Michel; Alexandre, Christophe; Le Coq, Yann

    2017-04-01

    Phase noise or frequency noise is a key metric to evaluate the short-term stability of a laser. This property is of great interest for the applications but delicate to characterize, especially for narrow linewidth lasers. In this Letter, we demonstrate a digital cross-correlation scheme to characterize the absolute phase noise of sub-hertz linewidth lasers. Three 1542 nm ultra-stable lasers are used in this approach. For each measurement, two lasers act as references to characterize a third one. Phase noise power spectral density from 0.5 Hz to 0.8 MHz Fourier frequencies can be derived for each laser by a mere change in the configuration of the lasers. To the best of our knowledge, this is the first time showing the phase noise of sub-hertz linewidth lasers with no reference limitation. We also present an analysis of the laser phase noise performance.

  12. Review of the Maxwell-Heaviside-Hertz form classical electromagnetic theory.

    OpenAIRE

    日高, 建彦

    2009-01-01

    We review the Maxwell-Heaviside-Hertz classical electromagnetic theory constructed with magnetic filed B and electricfield E. The theory is incomplete because it can not give the correct electromagnetic induction outside of the ideal longsolenoid coil. Another classical electromagnetic theory, constructed with a suitable Lagrangian including the potentials Aand φ and the action principle, would produce satisfactory results. The potentials A and φ are the main roles in, not onlyquantum mechani...

  13. Toward real-time detection of deep tissue injury risk in wheelchair users using Hertz contact theory

    National Research Council Canada - National Science Library

    Agam, Limor; Gefen, Amit

    2008-01-01

    This study assessed the suitability of a new portable system that is based on Hertz's contact theory for evaluating internal gluteal muscle stresses under the ischial tuberosities of wheelchair users...

  14. Rescattering effects and intermittent exponents in nucleus-nucleus interactions

    Energy Technology Data Exchange (ETDEWEB)

    Pajares, C. (Universidad de Santiago de Compostela (Spain). Dept. de Particulas Elementales)

    1991-04-11

    It is shown that the rescattering in nucleus-nucleus collisions provides a natural branching mechanism which explains the dependence of the intermittent exponents on the energy, projectile and target. The possibility of finding some new coherent phenomena by studying the dependence of the intermittent exponents on the number of collisions is discussed. (orig.).

  15. Lyapunov Exponents for the Intermittent Transition to Chaos

    CERN Document Server

    Hanssen, J; Hanssen, James; Wilcox, Walter

    1998-01-01

    The dependence of the Lyapunov exponent on the closeness parameter, illustrate two averaging procedures for defining Lyapunov exponents in such systems. First, we develop theoretical expressions for an isolated tangency channel in which the Lyapunov exponent is defined on single channel passes. Numerical simulations were done to compare theory to measurement across a range of $\\epsilon$ values. Next, as an illustration of defining the Lyapunov exponent on many channel passes, a simulation of the intermittent transition in the logistic map is described. The modified theory for the channels is explained and a simple model for the gate entrance rates is constructed. An important correction due to the discrete nature of the iterative flow is identified and incorporated in an improved model. Realistic fits to the data were made for the Lyapunov exponents from the logistic gate and from the full simulation. A number of additional corrections which could improve the treatment of the gates are identified and briefly ...

  16. Self-esteem, narcissism, and stressful life events: Testing for selection and socialization.

    Science.gov (United States)

    Orth, Ulrich; Luciano, Eva C

    2015-10-01

    We examined whether self-esteem and narcissism predict the occurrence of stressful life events (i.e., selection) and whether stressful life events predict change in self-esteem and narcissism (i.e., socialization). The analyses were based on longitudinal data from 2 studies, including samples of 328 young adults (Study 1) and 371 adults (Study 2). The effects of self-esteem and narcissism were mutually controlled for each other and, moreover, controlled for effects of depression. After conducting the study-level analyses, we meta-analytically aggregated the findings. Self-esteem had a selection effect, suggesting that low self-esteem led to the occurrence of stressful life events; however, this effect became nonsignificant when depression was controlled for. Regardless of whether depression was controlled for or not, narcissism had a selection effect, suggesting that high narcissism led to the occurrence of stressful life events. Moreover, stressful life events had a socialization effect on self-esteem, but not on narcissism, suggesting that the occurrence of stressful life events decreased self-esteem. Analyses of trait-state models indicated that narcissism consisted almost exclusively of perfectly stable trait variance, providing a possible explanation for the absence of socialization effects on narcissism. The findings have significant implications because they suggest that a person's level of narcissism influences whether stressful life events occur, and that self-esteem is shaped by the occurrence of stressful life events. Moreover, we discuss the possibility that depression mediates the selection effect of low self-esteem on stressful life events. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

  17. Allometric exponents do not support a universal metabolic allometry.

    Science.gov (United States)

    White, Craig R; Cassey, Phillip; Blackburn, Tim M

    2007-02-01

    The debate about the value of the allometric scaling exponent (b) relating metabolic rate to body mass (metabolic rate = a x mass(b)) is ongoing, with published evidence both for and against a 3/4-power scaling law continuing to accumulate. However, this debate often revolves around a dichotomous distinction between the 3/4-power exponent predicted by recent models of nutrient distribution networks and a 2/3 exponent predicted by Euclidean surface-area-to-volume considerations. Such an approach does not allow for the possibility that there is no single "true" exponent. In the present study, we conduct a meta-analysis of 127 interspecific allometric exponents to determine whether there is a universal metabolic allometry or if there are systematic differences between taxa or between metabolic states. This analysis shows that the effect size of mass on metabolic rate is significantly heterogeneous and that, on average, the effect of mass on metabolic rate is stronger for endotherms than for ectotherms. Significant differences between scaling exponents were also identified between ectotherms and endotherms, as well as between metabolic states (e.g., rest, field, and exercise), a result that applies to b values estimated by ordinary least squares, reduced major axis, and phylogenetically correct regression models. The lack of support for a single exponent model suggests that there is no universal metabolic allometry and represents a significant challenge to any model that predicts only a single value of b.

  18. Geometric critical exponents in classical and quantum phase transitions.

    Science.gov (United States)

    Kumar, Prashant; Sarkar, Tapobrata

    2014-10-01

    We define geometric critical exponents for systems that undergo continuous second-order classical and quantum phase transitions. These relate scalar quantities on the information theoretic parameter manifolds of such systems, near criticality. We calculate these exponents by approximating the metric and thereby solving geodesic equations analytically, near curvature singularities of two-dimensional parameter manifolds. The critical exponents are seen to be the same for both classical and quantum systems that we consider, and we provide evidence about the possible universality of our results.

  19. [A historic case of Wegener's granulomatosis: the physicist who discovered the electromagnetic waves: Heinrich Hertz].

    Science.gov (United States)

    Feldmann, H

    2005-06-01

    A diary and an extensive correspondence of Heinrich Hertz and his family provide a meticulous documentation of his life, made available by Albrecht Folsing in 1997 through a carefully investigated biography, which permit the conclusion that H. Hertz died of Wegener's granulomatosis, 45 years before this disease had been explored. WEGENER'S GRANULOMATOSIS: The symptoms of the granulomatosis, that was first described by Friedrich Wegener in 1936 and 1939 are presented in short with literal quotations of the author: It begins with a refractory cold that will last until the end, then follow involvement of the paranasal sinuses, ears, mucous lining of mouth and pharynx, slight fever, weakness, in the final phase dissemination with nephritis, septic fever, arthritis, myalgia, paralyses leading to total immobility, exitus. The etiology is not fully understood but probably based on immunoreaction. H. HERTZ: CURRICULUM VITAE: Born in Hamburg, Germany, in 1857: after secondary school academic training in physics at Dresden, Munic and Berlin. 1885 professor of physics in Karlsruhe, then starting in 1889 at Bonn. 1887/88 exploration of the electromagnetic waves, now the basis for all radio communication, and exploration of the photoelectric effect, the basis of solar techniques. Numerous highranking distinctions. H. HERTZ: The case history is presented in detail based on numerous literal quotations from personal letters and the diary. After a few banal affections involving the teeth and toes the systemic disease became manifest in summer 1892 with a refractory cold which remained the focus of treatment until death. Granulation tissue in the nose that was excised several times: no tuberculosis, no carcinoma. Otitis with purulent mastoiditis, in October 1892 mastoidectomy, persistent purulence. Early in 1893 diagnosis of nephritis. Extraction of a superior tooth, punturing of the maxillary sinus, then twice radical opening of the maxillary sinus. Painful ankylosis and paralyses

  20. The role of stressful life events on the cortisol reactivity patterns of breast cancer survivors.

    Science.gov (United States)

    Wan, Cynthia; Couture-Lalande, Marie-Ève; Lebel, Sophie; Bielajew, Catherine

    2017-12-01

    Atypical patterns of cortisol secretion following an acute stressor have been commonly reported in breast cancer survivors. Stressful life events have been associated with blunted acute cortisol levels in other populations. The purpose of this study was to explore the role of stressful life events on cortisol secretion patterns of breast cancer survivors following an acute stressor. The Trier Social Stress (TSST) was used to elicit a moderate stress response in breast cancer survivors (n = 19) and a control group (n = 17). Saliva samples were collected before, during and after the TSST to provide cortisol concentrations. During recovery, we recorded the frequency and subjective impact of stressful life events in the past year using the Life Experience Survey. Simple regressions analyses were performed; results suggest no group differences between the total number of stressful life events and their subjective impact. However, the total number of stressful life events as well as their subjective impact correlated negatively with the peak cortisol concentration in breast cancer survivors. The cumulative effect of stressful life events, positive and negative, may impact the endocrine stress system of breast cancer survivors more so than that of women with no history of cancer.

  1. Number of recent stressful life events and incident cardiovascular disease: Moderation by lifetime depressive disorder.

    Science.gov (United States)

    Berntson, Jessica; Patel, Jay S; Stewart, Jesse C

    2017-08-01

    We investigated whether number of recent stressful life events is associated with incident cardiovascular disease (CVD) and whether this relationship is stronger in adults with a history of clinical depression. Prospective data from 28,583 U.S. adults (mean age=45years) initially free of CVD who participated in Waves 1 (2001-2002) and 2 (2004-2005) of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) were examined. Number of past-year stressful life events (Wave 1), lifetime depressive disorder (Wave 1), and incident CVD (Wave 2) were determined by structured interviews. There were 1069 cases of incident CVD. Each additional stressful life event was associated with a 15% increased odds of incident CVD [Odds Ratio (OR)=1.15, 95% Confidence Interval (CI): 1.11, 1.19]. As hypothesized, a stressful life events by lifetime depressive disorder interaction was detected (P=0.003). Stratified analyses indicated that stressful life events had a stronger association with incident CVD among adults with (OR=1.18, 95% CI: 1.10, 1.27, n=4908) versus without (OR=1.10, 95% CI: 1.07, 1.14, n=23,675) a lifetime depressive disorder. Our findings suggest that a greater number of recent stressful life events elevate the risk of new-onset CVD and that this risk is potentiated in adults with a history of clinical depression. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Stressful life events preceding the onset of depression in Asian patients with major depressive disorder.

    Science.gov (United States)

    Park, Subin; Hatim, Ahmad; Si, Tian-Mei; Jeon, Hong Jin; Srisurapanont, Manit; Bautista, Dianne; Liu, Shen-ing; Chua, Hong Choon; Hong, Jin Pyo

    2015-12-01

    Previous studies have identified the significant role of stressful life events in the onset of depressive episodes. However, there is a paucity of cross-national studies on stressful life events that precede depression. We aimed to compare types of stressful life events associated with the onset of depressive episodes in patients with major depressive disorder (MDD) in five Asian countries. A total of 507 outpatients with MDD were recruited in China (n = 114), South Korea (n = 101), Malaysia (n = 90), Thailand (n = 103) and Taiwan (n = 99). All patients were assessed with the Mini-International Neuropsychiatric Interview and the List of Threatening Experiences. The prevalence of each type of stressful life events was calculated and compared between each country. The type of stressful life event that preceded the onset of a depressive episode differed between patients in China and Taiwan and those in South Korea, Malaysia and Thailand. Patients in China and Taiwan were less likely to report interpersonal relationship problems and occupational/financial problems than patients in South Korea, Malaysia and Thailand. Understanding the nature and basis of culturally determined susceptibilities to specific stressful life events is critical for establishing a policy of depression prevention and providing effective counseling services for depressed patients. © The Author(s) 2015.

  3. On some properties of the discrete Lyapunov exponent

    Energy Technology Data Exchange (ETDEWEB)

    Amigo, Jose M. [Centro de Investigacion Operativa, Universidad Miguel Hernandez Avda. de la Universidad s/n. 03202 Elche (Spain)], E-mail: jm.amigo@umh.es; Kocarev, Ljupco [Macedonian Academy of Sciences and Arts, Skopje (Macedonia, The Former Yugoslav Republic of); Institute for Nonlinear Science, University of California San Diego, 9500 Gilman Drive. La Jolla, CA 92093-0402 (United States)], E-mail: lkocarev@ucsd.edu; Szczepanski, Janusz [Institute of Fundamental Technological Research, Polish Academy of Sciences, Swietokrzyska 21, 00-049 Warsaw, and Kazimierz Wielki University in Bydgoszcz (Poland)], E-mail: jszczepa@ippt.gov.pl

    2008-10-06

    One of the possible by-products of discrete chaos is the application of its tools, in particular of the discrete Lyapunov exponent, to cryptography. In this Letter we explore this question in a very general setting.

  4. A MONTE-CARLO METHOD FOR ESTIMATING THE CORRELATION EXPONENT

    NARCIS (Netherlands)

    MIKOSCH, T; WANG, QA

    We propose a Monte Carlo method for estimating the correlation exponent of a stationary ergodic sequence. The estimator can be considered as a bootstrap version of the classical Hill estimator. A simulation study shows that the method yields reasonable estimates.

  5. Impact of Stressful Life Events on Patients with Chronic Obstructive Pulmonary Disease.

    Science.gov (United States)

    Yu, Tsung; Frei, Anja; Ter Riet, Gerben; Puhan, Milo A

    2017-11-01

    There is a general notion that stressful life events may cause mental and physical health problems. We aimed to describe stressful life events reported by patients with chronic obstructive pulmonary disease (COPD) and to assess their impact on health outcomes and behaviors. Two hundred and sixty-six primary care patients who participated in the ICE COLD ERIC cohort study were asked to document any stressful life events in the past 3 years. We assessed the before-after (the event) changes for symptoms of depression and anxiety, health status, dyspnea-related quality of life, exacerbations, cigarette use, and physical activity. We used linear regression analysis to estimate the crude and adjusted magnitude of the before-after changes. About 41% (110/266) of patients reported the experience of any stressful life events and "death of relatives/important persons" was most common (31%). After accounting for age, sex, living status, lung function, and anxiety/depression status at baseline, experiencing any stressful life events was associated with a 0.9-point increase on the depression scale (95% CI 0.3 to 1.4), a 0.8-point increase on the anxiety scale (95% CI 0.3 to 1.3), and a 0.8-point decrease in the physical activity score (95% CI -1.6 to 0). Experiencing stressful life events was associated with a small to moderate increase in symptoms of depression and anxiety in COPD, but no discernable effect was found for other physical outcomes. However, confirmation of these results in other COPD cohorts and identification of patients particularly vulnerable to stressful life events are needed. © 2017 S. Karger AG, Basel.

  6. Stressful life events and psychological dysfunction in Complex Regional Pain Syndrome type I.

    Science.gov (United States)

    Geertzen, J H; de Bruijn-Kofman, A T; de Bruijn, H P; van de Wiel, H B; Dijkstra, P U

    1998-06-01

    To determine to what extent stressful life events and psychological dysfunction play a role in the pathogenesis of Complex Regional Pain Syndrome type I (CRPS). A comparative study between a CRPS group and a control group. Stressful life events and psychological dysfunction evaluation was performed with a life event rating list and the Symptom Checklist-90 (SCL-90). A university hospital. The CRPS group consisted of 24 patients with a history of upper extremity CRPS of less than 3 months. The control group consisted of 42 hand pathology patients waiting for elective hand surgery within the next 24 hours. Stressful life event rating was measured using the Social Readjustment Rating Scale. Psychological dysfunction was measured using the SCL-90. Stressful life events were experienced by 19 patients (79.2%) in the CRPS group and by 9 patients (21.4%) in the control group. This difference was significant. Testing of psychological dysfunction (SCL-90) in CRPS patients and the control group demonstrated some significant differences: male patients were more anxious than male controls; female patients were statistically more depressed, had feelings of inadequacy, and were emotionally less stable than female controls. In multivariate analysis, no significant differences were found across gender, age, or gender x group interactions. Of the SCL-90 dimensions, only insomnia correlated with the experienced stressful life events. Stressful life events are more common in the CRPS group, which indicates that there may be a multiconditional model of CRPS. The experience of stressful life events besides trauma or surgery are risk factors, not causes, in such a model.

  7. Images and Conventions: Kantianism, empiricism, and conventionalism in Hertz's and Poincaré's philosophies of space and mechanics

    DEFF Research Database (Denmark)

    Lützen, Jesper

    2007-01-01

    Artiklen analyserer kantianske, empiricistiske og konventionalistiske tendenser i Heinrich Hertz's Prinzipien der Mechanik (1894) og sammenligner dem med tilsvarende tendenser i Henri Poincaré's La science et l'hypothèse (1902). Derved belyses Poincaré's reaktion på kantianismen......Artiklen analyserer kantianske, empiricistiske og konventionalistiske tendenser i Heinrich Hertz's Prinzipien der Mechanik (1894) og sammenligner dem med tilsvarende tendenser i Henri Poincaré's La science et l'hypothèse (1902). Derved belyses Poincaré's reaktion på kantianismen...

  8. Lyapunov exponent for pure and random Fibonacci chains

    Science.gov (United States)

    Velhinho, M. T.; Pimentel, I. R.

    2000-01-01

    We study the Lyapunov exponent for electron and phonon excitations, in pure and random Fibonacci quasicrystal chains, using an exact real-space renormalization-group method, which allows the calculation of the Lyapunov exponent as a function of the energy. It is shown that the Lyapunov exponent on a pure Fibonacci chain has a self-similar structure, characterized by a scaling index that is independent of the energy for the electron excitations, ``diagonal'' or ``off-diagonal'' quasiperiodic, but is a function of the energy for the phonon excitations. This scaling behavior implies the vanishing of the Lyapunov exponent for the states on the spectrum, and hence the absence of localization on the Fibonacci chain, for the various excitations considered. It is also shown that disordered Fibonacci chains, with random tiling that introduces phason flips at certain sites on the chain, exhibit the same Lyapunov exponent as the pure Fibonacci chain, and hence this type of disorder is irrelevant, either in the case of electron or phonon excitations.

  9. Critical exponents from AdS/CFT with flavor

    Science.gov (United States)

    Karch, Andreas; O'Bannon, Andy; Yaffe, Laurence G.

    2009-09-01

    We use the AdS/CFT correspondence to study the thermodynamics of massive Script N = 2 supersymmetric hypermultiplet flavor fields coupled to Script N = 4 supersymmetric SU(Nc) Yang-Mills theory, formulated on curved four-manifolds, in the limits of large Nc and large 't Hooft coupling. The gravitational duals are probe D-branes in global thermal AdS. These D-branes may undergo a topology-changing transition in the bulk. The D-brane embeddings near the point of the topology change exhibit a scaling symmetry. The associated scaling exponents can be either real- or complex-valued. Which regime applies depends on the dimensionality of a collapsing submanifold in the critical embedding. When the scaling exponents are complex-valued, a first-order transition associated with the flavor fields appears in the dual field theory. Real scaling exponents are expected to be associated with a continuous transition in the dual field theory. For one example with real exponents, the D7-brane, we study the transition in detail. We find two field theory observables that diverge at the critical point, and we compute the associated critical exponents. We also present analytic and numerical evidence that the transition expresses itself in the meson spectrum as a non-analyticity at the critical point. We argue that the transition we study is a true phase transition only when the 't Hooft coupling is strictly infinite.

  10. Are Stressful Life Events (SLEs) Associated with the Utilization of Substance Use Treatment-Related Services?

    Science.gov (United States)

    Cruz-Feliciano, Miguel A; Ferraro, Aimee; Witt Prehn, Angela

    2017-03-01

    This study described herein explored the association of stressful life events with the utilization of substance use treatment-related services among substance users living in Puerto Rico. A secondary data analysis was conducted using data collected by a research project entitled Puerto Rico Drug Abuse Research Development Program II (PRDARDP II). The study population consisted of 378 individuals from 18 to 35 years of age who were residents of the San Juan metropolitan area and who presented evidence of substance use in the 30 days prior to the interview. The analysis considered demographic data, information on patterns of substance use, substance use treatment history, stressful events, and depression and anxiety symptomatology. As the number of stressful life events increased, substance users were more likely to report having utilized substance use treatment-related services (OR = 1.11, 95% CI [1.06, 1.17], p events associated with the utilization of substance use treatment-related services. Despite the structural limitations associated with access to and with the quality of the services in the substance use treatment-related system of Puerto Rico, findings suggest that stressful life events play a significant role in the utilization of those services. Researchers and clinicians should consider screening for stressful life events in outreach and engagement strategies. At the same time, the assessment of stressful life events should be integrated into the treatment planning stage to support the recovery process of people with substance use disorders.

  11. Psychological distress and stressful life events in pediatric complex regional pain syndrome

    Science.gov (United States)

    Wager, Julia; Brehmer, Hannah; Hirschfeld, Gerrit; Zernikow, Boris

    2015-01-01

    BACKGROUND: There is little knowledge regarding the association between psychological factors and complex regional pain syndrome (CRPS) in children. Specifically, it is not known which factors precipitate CRPS and which result from the ongoing painful disease. OBJECTIVES: To examine symptoms of depression and anxiety as well as the experience of stressful life events in children with CRPS compared with children with chronic primary headaches and functional abdominal pain. METHODS: A retrospective chart study examined children with CRPS (n=37) who received intensive inpatient pain treatment between 2004 and 2010. They were compared with two control groups (chronic primary headaches and functional abdominal pain; each n=37), who also received intensive inpatient pain treatment. Control groups were matched with the CRPS group with regard to admission date, age and sex. Groups were compared on symptoms of depression and anxiety as well as stressful life events. RESULTS: Children with CRPS reported lower anxiety and depression scores compared with children with abdominal pain. A higher number of stressful life events before and after the onset of the pain condition was observed for children with CRPS. CONCLUSIONS: Children with CRPS are not particularly prone to symptoms of anxiety or depression. Importantly, children with CRPS experienced more stressful life events than children with chronic headaches or abdominal pain. Prospective long-term studies are needed to further explore the potential role of stressful life events in the etiology of CRPS. PMID:26035287

  12. Anisotropies in magnetic field evolution and local Lyapunov exponents

    Energy Technology Data Exchange (ETDEWEB)

    Tang, X.Z.; Boozer, A.H.

    2000-01-13

    The natural occurrence of small scale structures and the extreme anisotropy in the evolution of a magnetic field embedded in a conducting flow is interpreted in terms of the properties of the local Lyapunov exponents along the various local characteristic (un)stable directions for the Lagrangian flow trajectories. The local Lyapunov exponents and the characteristic directions are functions of Lagrangian coordinates and time, which are completely determined once the flow field is specified. The characteristic directions that are associated with the spatial anisotropy of the problem, are prescribed in both Lagrangian and Eulerian frames. Coordinate transformation techniques are employed to relate the spatial distributions of the magnetic field, the induced current density, and the Lorentz force, which are usually followed in Eulerian frame, to those of the local Lyapunov exponents, which are naturally defined in Lagrangian coordinates.

  13. OBSERVING LYAPUNOV EXPONENTS OF INFINITE-DIMENSIONAL DYNAMICAL SYSTEMS.

    Science.gov (United States)

    Ott, William; Rivas, Mauricio A; West, James

    2015-12-01

    Can Lyapunov exponents of infinite-dimensional dynamical systems be observed by projecting the dynamics into ℝ (N) using a 'typical' nonlinear projection map? We answer this question affirmatively by developing embedding theorems for compact invariant sets associated with C(1) maps on Hilbert spaces. Examples of such discrete-time dynamical systems include time-T maps and Poincaré return maps generated by the solution semigroups of evolution partial differential equations. We make every effort to place hypotheses on the projected dynamics rather than on the underlying infinite-dimensional dynamical system. In so doing, we adopt an empirical approach and formulate checkable conditions under which a Lyapunov exponent computed from experimental data will be a Lyapunov exponent of the infinite-dimensional dynamical system under study (provided the nonlinear projection map producing the data is typical in the sense of prevalence).

  14. Lyapunov exponents from geodesic spread in configuration space

    CERN Document Server

    Cerruti-Sola, M; Pettini, M; Cerruti-Sola, Monica; Franzosi, Roberto; Pettini, Marco

    1997-01-01

    The exact form of the Jacobi -- Levi-Civita (JLC) equation for geodesic spread is here explicitly worked out at arbitrary dimension for the configuration space manifold M_E = {q in R^N | V(q) < E} of a standard Hamiltonian system, equipped with the Jacobi (or kinetic energy) metric g_J. As the Hamiltonian flow corresponds to a geodesic flow on (M_E,g_J), the JLC equation can be used to study the degree of instability of the Hamiltonian flow. It is found that the solutions of the JLC equation are closely resembling the solutions of the standard tangent dynamics equation which is used to compute Lyapunov exponents. Therefore the instability exponents obtained through the JLC equation are in perfect quantitative agreement with usual Lyapunov exponents. This work completes a previous investigation that was limited only to two-degrees of freedom systems.

  15. Interaction between genetic polymorphisms and stressful life events in first episode depression

    DEFF Research Database (Denmark)

    Bukh, Jens Drachmann; Bock, Camilla; Vinberg, Maj

    2009-01-01

    BACKGROUND: A polymorphism in the serotonin transporter (5-HTT) gene seems to moderate the influence of stressful life events on depression. However, the results from previous studies of gene-environment interactions in depression are inconsistent and might be confounded by the history...... of depression among participants. METHOD: We applied a case-only design, including 290 ethnically homogeneous patients suffering exclusively from first episode depression. Psychiatric mo-morbidity, personality traits and disorders and stressful life events in a six months period preceding onset of depression...... of stressful life events prior to onset of depression, also when corrected for the effect of age, gender, marital status, personality disorder, neuroticism, and severity of depressive symptoms at the time of interview. CONCLUSION: Polymorphisms in the genes encoding the serotonin transporter and the brain...

  16. [May a sibling relationship be protective in coping with parental illness/stressful life events?].

    Science.gov (United States)

    Lange, Sabine; Lehmkuhl, Ulrike

    2012-01-01

    From a psychosocial point of view, the children of parents who suffer from cancer are regarded as not being sufficiently provided for, as well as being at greater risk for developing a psychiatric illness. Protective factors are marital satisfaction, open communication within the family and a good relationship with their parents. Results stemming from research on divorce have shown that sibling relationships may act as a protective factor against suffering a psychiatric illness after a stressful life event. The aim of this literature review is to examine the possible influence that a positive sibling relationship may have in coping with parental (oncological) illness/stressful life events. A review of the existing literature has revealed that little research has been conducted to this date addressing the question at hand. Altogether, the existence of a positive sibling relationship has shown to have a protective effect when having to deal with the burden of a stressful life event.

  17. Do stressful life events predict medical treatment outcome in first episode of depression?

    DEFF Research Database (Denmark)

    Bock, Camilla; Bukh, Jens Drachmann; Vinberg, Maj

    2009-01-01

    BACKGROUND: It is unclear whether medical treatment outcome in first episode depression differ for patients with and without stressful life events prior to onset of depression. METHODS: Patients discharged with a diagnosis of a single depressive episode from a psychiatric in- or outpatient hospital...... adequate trials of antidepressant treatment. RESULTS: A total of 399 patients participated in the interview and among these 301 patients obtained a SCAN diagnosis of a single depressive episode. A total of 62.8% of the 301 patients experienced at least one moderate to severe stressful life event in a 6......: Medical treatment outcome in first episode depression does not depend on the prevalence of moderate to severe stressful life events prior to symptom onset....

  18. Universal exponent for transport in mixed Hamiltonian dynamics

    Science.gov (United States)

    Alus, Or; Fishman, Shmuel; Meiss, James D.

    2017-09-01

    We compute universal distributions for the transition probabilities of a Markov model for transport in the mixed phase space of area-preserving maps and verify that the survival probability distribution for trajectories near an infinite island-around-island hierarchy exhibits, on average, a power-law decay with exponent γ =1.57 . This exponent agrees with that found from simulations of the Hénon and Chirikov-Taylor maps. This provides evidence that the Meiss-Ott Markov tree model describes the transport for mixed systems.

  19. Lyapunov exponents and particle dispersion in drift wave turbulence

    DEFF Research Database (Denmark)

    Pedersen, T.S.; Michelsen, Poul; Juul Rasmussen, J.

    1996-01-01

    The Hasegawa-Wakatani model equations for resistive drift waves are solved numerically for a range of values of the coupling due to the parallel electron motion. The largest Lyapunov exponent, lambda(1), is calculated to quantify the unpredictability of the turbulent flow and compared to other...... characteristic inverse time scales of the turbulence such as the linear growth rate and Lagrangian inverse time scales obtained by tracking virtual fluid particles. The results show a correlation between lambda(1) and the relative dispersion exponent, lambda(p), as well as to the inverse Lagrangian integral time...... contribute most to the relative dispersion of particles. (C) 1996 American Institute of Physics....

  20. Implementation of Inquiry Strategy on Exponent, Roots and Logarithm

    Science.gov (United States)

    Sulistyowaty, R. K.; Prafianti, R. A.

    2017-09-01

    The aim of this research is to enhancing students’ learning outcomes on exponent, roots, and logarithm through the implementation of Inquiry strategy. This research is a descriptive qualitative research with classroom action research approach which was done in three cycles. Each cycle consists of 4 steps, those are: planning, acting, observing and reflecting. This research had been conducted with 30 students (17 female and 13 male) studying in the 10th grade. Data was collected from students through documentation, observation, and test. The data was analyzed using descriptive qualitative and quantitative methods. The findings revealed that Inquiry strategy affected students’ learning outcomes on exponent, roots, and logarithm.

  1. Nano-Hertz Gravitational Waves Searches with Interferometric Pulsar Timing Experiments

    CERN Document Server

    Tinto, Massimo

    2011-01-01

    We estimate the sensitivity to nano-Hertz gravitational waves of pulsar timing experiments in which two highly-stable millisecond pulsars are tracked simultaneously with two neighboring radio telescopes that are referenced to the same time-keeping subsystem (i.e. "the clock"). By taking the difference of the two time-of-arrival residual data streams we can exactly cancel the clock noise in the combined data set, thereby enhancing the sensitivity to gravitational waves. We estimate that, in the band ($10^{-9} - 10^{-8}$) Hz, this "interferometric" pulsar timing technique can potentially improve the sensitivity to gravitational radiation by almost two orders of magnitude over that of single-telescopes. Interferometric pulsar timing experiments could be performed with neighboring pairs of antennas of the forthcoming large arraying projects.

  2. Milli-Hertz Gravitational Waves: LISA and LISA PathFinder

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, H; Hollington, D; Wass, P [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom); Canizares, P; Conchillo, A; Gesa, L; Lloro, I; Lobo, A; Mateos, I; Sopuerta, CF [Instituto de Ciencias del Espacio, CSIC, Campus UAB, Facultat de Ciencies, Torre C-5 Parell, 2a Planta, E-08193 Bellaterra (Cerdanyola del Valles), Barcelona (Spain); Chmeissani, M; Puigdengoles, C [Institut de Fisica d' Altes Energies (IFAE), Edifici C, Universitat Autonoma de Barcelona, 08193 Bellaterra, (Barcelona) (Spain); Diaz-Aguilo, M; Garcia-Berro, E; Gibert, F [Institut d' Estudis Espacials de Catalunya (IEEC), Edifici Nexus, Gran Capita 2-4, 08034 Barcelona (Spain); Grimani, C [Universita degli Studi di Urbino, and INFN Florence, Dipartimento DiSBeF, Via Santa Chiara 27, 61029 Urbino (Italy); Hajdas, W [Department of Particles and Matter, Paul Scherrer Institut, ODRA 120, 5232 Villigen (Switzerland); Nofrarias, M [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Callinstrasse 38, D-30167 Hannover (Germany); Ramos-Castro, J [Departament d' Enginyeria Electronica, UPC, Campus Nord, Edif. C4, Jordi Girona 1-3, 08034 Barcelona (Spain); Sanjuan, J, E-mail: lobo@ieec.fcr.es [Department of Physics, University of Florida, NPB-22258 PO Box 118 440, Gainesville FL 32611-8440 (United States)

    2011-09-22

    Ground based GW detectors are limited at their lower frequency band (1-10 Hz) by settlement gravity gradients and seismic noise, and their sensitivity peaks at around 100 Hz. Sources in this band are mostly short duration signals, and their rates uncertain. Going down to milli-Hertz frequencies significantly increases the number and types of available sources. LISA was planned with the idea to explore a likely richer region of the GW spectrum, beyond that accessible to ground detectors; the latter are however expected to produce the first GW observations. In this paper I will present the main LISA concepts; in particular, emphasis will be placed on LISAPathFinder, the ESA precursor of LISA, in which our research group in Barcelona is heavily involved.

  3. Lyapunov exponent for aging process in induction motor

    Science.gov (United States)

    Bayram, Duygu; Ünnü, Sezen Yıdırım; Şeker, Serhat

    2012-09-01

    Nonlinear systems like electrical circuits and systems, mechanics, optics and even incidents in nature may pass through various bifurcations and steady states like equilibrium point, periodic, quasi-periodic, chaotic states. Although chaotic phenomena are widely observed in physical systems, it can not be predicted because of the nature of the system. On the other hand, it is known that, chaos is strictly dependent on initial conditions of the system [1-3]. There are several methods in order to define the chaos. Phase portraits, Poincaré maps, Lyapunov Exponents are the most common techniques. Lyapunov Exponents are the theoretical indicator of the chaos, named after the Russian mathematician Aleksandr Lyapunov (1857-1918). Lyapunov Exponents stand for the average exponential divergence or convergence of nearby system states, meaning estimating the quantitive measure of the chaotic attractor. Negative numbers of the exponents stand for a stable system whereas zero stands for quasi-periodic systems. On the other hand, at least if one of the exponents is positive, this situation is an indicator of the chaos. For estimating the exponents, the system should be modeled by differential equation but even in that case mathematical calculation of Lyapunov Exponents are not very practical and evaluation of these values requires a long signal duration [4-7]. For experimental data sets, it is not always possible to acquire the differential equations. There are several different methods in literature for determining the Lyapunov Exponents of the system [4, 5]. Induction motors are the most important tools for many industrial processes because they are cheap, robust, efficient and reliable. In order to have healthy processes in industrial applications, the conditions of the machines should be monitored and the different working conditions should be addressed correctly. To the best of our knowledge, researches related to Lyapunov exponents and electrical motors are mostly

  4. An inquiry-based approach to the Franck-Hertz experiment

    Science.gov (United States)

    Persano Adorno, Dominique; Pizzolato, Nicola

    2016-05-01

    The practice of scientists and engineers is today exerted within interdisciplinary contexts, placed at the intersections of different research fields, including nanoscale science. The development of the required competences is based on an effective science and engineering instruction, which should be able to drive the students towards a deeper understanding of quantum mechanics fundamental concepts and, at the same time, strengthen their reasoning skills and transversal abilities. In this study we report the results of an inquiry-driven learning path experienced by a sample of 12 electronic engineering undergraduates engaged to perform the Franck-Hertz experiment. Before being involved in this experimental activity, the students received a traditional lecture-based instruction on the fundamental concepts of quantum mechanics, but their answers to an open-ended questionnaire, administered at the beginning of the inquiry activity, demonstrated that the acquired knowledge was characterized by a strictly theoretical vision of quantum science, basically in terms of an artificial mathematical framework having very poor connections with the real world. The Franck Hertz experiment was introduced to the students by starting from the problem of finding an experimental confirmation of the Bohr's postulates asserting that atoms can absorb energy only in quantum portions. The whole activity has been videotaped and this allowed us to deeply analyse the student perception's change about the main concepts of quantum mechanics. We have found that the active participation to this learning experience favored the building of cognitive links among student theoretical perceptions of quantum mechanics and their vision of quantum phenomena, within an everyday context of knowledge. Furthermore, our findings confirm the benefits of integrating traditional lecture-based instruction on quantum mechanics with learning experiences driven by inquiry-based teaching strategies.

  5. Inverted rank distributions: Macroscopic statistics, universality classes, and critical exponents

    Science.gov (United States)

    Eliazar, Iddo; Cohen, Morrel H.

    2014-01-01

    An inverted rank distribution is an infinite sequence of positive sizes ordered in a monotone increasing fashion. Interlacing together Lorenzian and oligarchic asymptotic analyses, we establish a macroscopic classification of inverted rank distributions into five “socioeconomic” universality classes: communism, socialism, criticality, feudalism, and absolute monarchy. We further establish that: (i) communism and socialism are analogous to a “disordered phase”, feudalism and absolute monarchy are analogous to an “ordered phase”, and criticality is the “phase transition” between order and disorder; (ii) the universality classes are characterized by two critical exponents, one governing the ordered phase, and the other governing the disordered phase; (iii) communism, criticality, and absolute monarchy are characterized by sharp exponent values, and are inherently deterministic; (iv) socialism is characterized by a continuous exponent range, is inherently stochastic, and is universally governed by continuous power-law statistics; (v) feudalism is characterized by a continuous exponent range, is inherently stochastic, and is universally governed by discrete exponential statistics. The results presented in this paper yield a universal macroscopic socioeconophysical perspective of inverted rank distributions.

  6. Error Exponents for Target-Class Detection with Nuisance Parameters

    National Research Council Canada - National Science Library

    Misra, Saswat; Tong, Lang

    2007-01-01

    ...) has at least one unknown component, we use the theory of adaptive tests to prove that there exists a test that achieves the same error exponent as if (gamma, theta) were known in some scenarios, but that there exists no such test in others.

  7. Density-scaling exponents and virial potential-energy correlation ...

    Indian Academy of Sciences (India)

    This paper investigates the relation between the density-scaling exponent γ and the virial potential energy correlation coefficient R at several thermodynamic state points in three dimensions for the generalized (2n, n) Lennard-Jones (LJ) system for n = 4, 9, 12, 18, as well as for the standard n = 6 LJ system in two,three, and ...

  8. Bayesian Estimation of the Logistic Positive Exponent IRT Model

    Science.gov (United States)

    Bolfarine, Heleno; Bazan, Jorge Luis

    2010-01-01

    A Bayesian inference approach using Markov Chain Monte Carlo (MCMC) is developed for the logistic positive exponent (LPE) model proposed by Samejima and for a new skewed Logistic Item Response Theory (IRT) model, named Reflection LPE model. Both models lead to asymmetric item characteristic curves (ICC) and can be appropriate because a symmetric…

  9. Analysis of Human Standing Balance by Largest Lyapunov Exponent

    Directory of Open Access Journals (Sweden)

    Kun Liu

    2015-01-01

    Full Text Available The purpose of this research is to analyse the relationship between nonlinear dynamic character and individuals’ standing balance by the largest Lyapunov exponent, which is regarded as a metric for assessing standing balance. According to previous study, the largest Lyapunov exponent from centre of pressure time series could not well quantify the human balance ability. In this research, two improvements were made. Firstly, an external stimulus was applied to feet in the form of continuous horizontal sinusoidal motion by a moving platform. Secondly, a multiaccelerometer subsystem was adopted. Twenty healthy volunteers participated in this experiment. A new metric, coordinated largest Lyapunov exponent was proposed, which reflected the relationship of body segments by integrating multidimensional largest Lyapunov exponent values. By using this metric in actual standing performance under sinusoidal stimulus, an obvious relationship between the new metric and the actual balance ability was found in the majority of the subjects. These results show that the sinusoidal stimulus can make human balance characteristics more obvious, which is beneficial to assess balance, and balance is determined by the ability of coordinating all body segments.

  10. determination of the power law exponent for southern highlands of ...

    African Journals Online (AJOL)

    Mgina

    ABSTRACT. The 1/7th power law is among the methods that have been used to extrapolate wind speed to the hub heights of wind turbines from the measuring levels. However, it tends to underestimate the actual long-term average wind speeds. In this paper, the power law exponent for Makambako, a site located in the ...

  11. Stressful life events and posttraumatic growth among police officers: A cross-sectional study.

    Science.gov (United States)

    Leppma, Monica; Mnatsakanova, Anna; Sarkisian, Khachatur; Scott, Olivia; Adjeroh, Leonie; Andrew, Michael E; Violanti, John M; McCanlies, Erin C

    2017-07-13

    Police officers often continue to face numerous threats and stressors in the aftermath of a disaster. To date, posttraumatic growth (PTG) has been studied primarily in the context of significant trauma; thus, it is not known whether stressful life events are associated with PTG. This study investigated the development of PTG among 113 police officers working in the New Orleans area following Hurricane Katrina. Hierarchical regression was used to evaluate if gratitude, social support, and satisfaction with life moderated the relationship between stressful life events (as measured by the total life stress score) and PTG, after adjustment for age, sex, race, level of involvement in Hurricane Katrina, and alcohol intake. Results indicate that stressful life events are independently associated with PTG. Gratitude, satisfaction with life, and social support were seen to moderate this relationship; as stressful life events increased so too did PTG-particularly among officers with higher levels of gratitude (B = 0.002, p ≤ .05), satisfaction with life (B = 0.002, p ≤ .05), and social support (B = 0.001, p ≤ .05). These findings suggest that promoting satisfaction with life, interpersonal support, and gratitude may be beneficial to those who are regularly at risk of trauma exposure. Copyright © 2017 John Wiley & Sons, Ltd.

  12. Origins of Early Adolescents' Hope: Personality, Parental Attachment, and Stressful Life Events

    Science.gov (United States)

    Otis, Kristin L.; Huebner, E. Scott; Hills, Kimberly J.

    2016-01-01

    Psychology has recently increased attention to identifying psychological qualities in individuals that indicate positive mental health, such as hope. In an effort to understand further the origins of hope, we examined the relations among parental attachment, stressful life events, personality variables, and hope in a sample of 647 middle school…

  13. The effects of structured writing assignments on processing stressful life events: an uncontroled study

    NARCIS (Netherlands)

    Schoutrop, M.; Lange, A.; Hanewald, G.; Duurland, C.; Bermond, B.

    1997-01-01

    In the present study the effectiveness of writing assignments in the treatment of individuals who have suffered traumatic or stressful life events is investigated. Thirty-two undergraduates participated in the study. The treatment consisted of five writing sessions of 45 min duration that took place

  14. Commentary: Beyond Stressful Life Events and Depression?--Reflections on Bogdan et al. (2014)

    Science.gov (United States)

    Belsky, Jay

    2014-01-01

    In light of continuing disagreement, even at the meta-analytic level, as to whether the gene- × -environment (G×E) interaction involving 5-HTTLPR and stressful life events (SLEs) predicts depression, Bogdan and associates (this issue, Bogdan et al., 2014) sought to extend research on what has become a highly controversial general (GxE) and…

  15. Depression symptoms and stressful life events among college students in Puerto Rico.

    Science.gov (United States)

    Reyes-Rodríguez, Mae Lynn; Rivera-Medina, Carmen L; Cámara-Fuentes, Luis; Suárez-Torres, Alba; Bernal, Guillermo

    2013-03-05

    The transition from adolescence to adulthood is associated with stressful adaptation experiences that may increase symptoms of depression. We explored the prevalence and sex differences of depressive symptoms and suicidal ideation in freshmen Latino college students in Puerto Rico, and identified stressful life events that could contribute to symptoms of depression. Two thousand one hundred sixty-three freshmen college students from the University of Puerto Rico (UPR) public education system were assessed for depression symptoms using the Beck Depression Inventory (BDI) and stressful life events using open questions. Nine percent of the sample reported depression symptoms at a moderate or severe level (BDI>20). Chi square analyses revealed a significantly higher prevalence for three of the stressful life events in females than males: relocation (10.2% females vs. 7.3% males; X(2) (1)=4.13, p=.042), break-up of a significant relationship (25.3% females vs. 17.8% males; X(2) (1)=13.76, pcollege, whereas for males a similar model without the relationship break-up variable resulted in a better fit. Freshmen college students present a broad range of depression symptoms and certain stressful life events are associated with an increased prevalence of depression symptoms. Early detection of depression and tailored prevention programs should be developed to improve both mental health and academic performance among the college population. Published by Elsevier B.V.

  16. Timing of Stressful Life Events Affects Stability and Change of Neuroticism

    NARCIS (Netherlands)

    Riese, Harriette; Snieder, Harold; Jeronimus, Bertus F.; Korhonen, Tellervo; Rose, Richard J.; Kaprio, Jaakko; Ormel, Johan

    2014-01-01

    Neuroticism is a predictor of many health problems. To study the determinants of within-subject change in neuroticism, three hypotheses were tested: (i) subjects who experienced stressful life events (SLEs) show an increase in neuroticism; (ii) high baseline neuroticism moderated this effect; and

  17. Green space as a buffer between stressful life events and health.

    NARCIS (Netherlands)

    Maas, J.; Berg, A. van den; Verheij, R.A.; Groenewegen, P.P.

    2010-01-01

    This study investigates whether the presence of green space can attenuate negative health impacts of stressful life events. Individual-level data on health and socio-demographic characteristics were drawn from a representative two-stage sample of 4529 Dutch respondents to the second Dutch National

  18. Green space as a buffer between stressful life events and health

    NARCIS (Netherlands)

    van den Berg, Agnes E.; Maas, Jolanda; Verheij, Robert A.; Groenewegen, Peter P.

    This study investigates whether the presence of green space can attenuate negative health impacts of stressful life events. Individual-level data on health and socio-demographic characteristics were drawn from a representative two-stage sample of 4529 Dutch respondents to the second Dutch National

  19. Green space as a buffer between stressful life events and health

    NARCIS (Netherlands)

    Berg, van den A.E.; Maas, J.; Verheij, R.A.; Groenewegen, P.P.

    2010-01-01

    This study investigates whether the presence of green space can attenuate negative health impacts of stressful life events. Individual-level data on health and socio-demographic characteristics were drawn from a representative two-stage sample of 4529 Dutch respondents to the second Dutch National

  20. The influence of pubertal timing and stressful life events on depression and delinquency among Chinese adolescents.

    Science.gov (United States)

    Chen, Jie; Yu, Jing; Wu, Yun; Zhang, Jianxin

    2015-06-01

    This study aimed to investigate the influences of pubertal timing and stressful life events on Chinese adolescents' depression and delinquency. Sex differences in these influences were also examined. A large sample with 4,228 participants aged 12-15 years (53% girls) was recruited in Beijing, China. Participants' pubertal development, stressful life events, depressive symptoms, and delinquency were measured using self-reported questionnaires. Both early maturing girls and boys displayed more delinquency than their same-sex on-time and late maturing peers. Early maturing girls displayed more depressive symptoms than on-time and late maturing girls, but boys in the three maturation groups showed similar levels of depressive symptoms. The interactive effects between early pubertal timing and stressful life events were significant in predicting depression and delinquency, particularly for girls. Early pubertal maturation is an important risk factor for Chinese adolescents' depression and delinquency. Stressful life events intensified the detrimental effects of early pubertal maturation on adolescents' depression and delinquency, particularly for girls. © 2015 The Institute of Psychology, Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

  1. Major stressful life events in adulthood and risk of multiple sclerosis

    DEFF Research Database (Denmark)

    Nielsen, Nete Munk; Bager, Peter; Simonsen, Jacob

    2014-01-01

    It is unclear whether psychological stress is associated with increased risk of multiple sclerosis (MS). We studied the association between major stressful life events and MS in a nationwide cohort study using death of a child or a spouse or marital dissolution as indicators of severe stress....

  2. Depression symptoms and stressful life events among college students in Puerto Rico

    Science.gov (United States)

    Reyes-Rodríguez, Mae Lynn; Rivera-Medina, Carmen L.; Cámara-Fuentes, Luis; Suárez-Torres, Alba; Bernal, Guillermo

    2012-01-01

    Background The transition from adolescence to adulthood is associated with stressful adaptation experiences that may increase symptoms of depression. We explored the prevalence and sex differences of depressive symptoms and suicidal ideation in freshmen Latino college students in Puerto Rico, and identified stressful life events that could contribute to symptoms of depression. Methods Two thousand one hundred sixty-three freshmen college students from the University of Puerto Rico (UPR) public education system were assessed for depression symptoms using the Beck Depression Inventory (BDI) and stressful life events using open questions. Results Nine percent of the sample reported depression symptoms at a moderate or severe level (BDI ≥ 20). Chi square analyses revealed a significantly higher prevalence for three of the stressful life events in females than males: relocation (10.2% females vs. 7.3% males; X2 (1) = 4.13, p=.042), break-up of a significant relationship (25.3% females vs. 17.8% males; X2 (1) = 13.76, pcollege, whereas for males a similar model without the relationship break-up variable resulted in a better fit. Conclusions Freshmen college students present a broad range of depression symptoms and certain stressful life events are associated with an increased prevalence of depression symptoms. Early detection of depression and tailored prevention programs should be developed to improve both mental health and academic performance among the college population. PMID:22939390

  3. Role of stressful life events in induction or exacerbation of psoriasis and chronic urticaria

    Directory of Open Access Journals (Sweden)

    Malhotra S

    2008-01-01

    Full Text Available Background: The possibility of a causal influence of emotional stress, especially of stressful life events, on the course of various skin diseases has long been postulated. Previous reports addressing its influence on skin psoriasis and chronic urticaria have been mainly anecdotal. Objective: The aim of this study was to evaluate the stressful events of life within 1 year preceding onset or exacerbation of skin disease in patients of psoriasis vulgaris and chronic urticaria. Method: Fifty consecutive clinically diagnosed psoriasis patients and 50 consecutive clinically diagnosed chronic urticaria patients were examined clinically and administered Gurmeet Singh′s presumptive stressful life events scale. Results: Stressful life events were seen in 26% of the patients in the psoriasis vulgaris group and 16% of the patients in the chronic urticaria group within 1 year preceding onset or exacerbation of skin disease. In the psoriasis vulgaris group, the most common stressful life event seen was financial loss or problems (8%, followed by death of close family member (4%, sexual problems (4%, family conflict (2%, major personal illness or injury (2%,and transfer or change in working conditions (2%, failure in examinations (2%, family member unemployed (2%, illness of family member (2%, getting married or engaged (2%, miscellaneous (2%. In the chronic urticaria group, the most common stressful life event seen was death of a close family member (6%, followed by family conflict (2%, financial loss or problems (2%, sexual problems (2%, illness of family member (2%, getting married or engaged (2%, trouble at work with colleagues, superiors, or subordinates (2%, going on a pleasure trip (2% and extramarital relations (2%. Conclusion: Psychological stress plays a significant role in triggering or exacerbating dermatological diseases. Our study indicates the role of relaxation therapies and stress management programs in chronic diseases such as psoriasis

  4. Role of stressful life events in induction or exacerbation of psoriasis and chronic urticaria.

    Science.gov (United States)

    Malhotra, S K; Mehta, Vivek

    2008-01-01

    The possibility of a causal influence of emotional stress, especially of stressful life events, on the course of various skin diseases has long been postulated. Previous reports addressing its influence on skin psoriasis and chronic urticaria have been mainly anecdotal. The aim of this study was to evaluate the stressful events of life within 1 year preceding onset or exacerbation of skin disease in patients of psoriasis vulgaris and chronic urticaria. Fifty consecutive clinically diagnosed psoriasis patients and 50 consecutive clinically diagnosed chronic urticaria patients were examined clinically and administered Gurmeet Singh's presumptive stressful life events scale. Stressful life events were seen in 26% of the patients in the psoriasis vulgaris group and 16% of the patients in the chronic urticaria group within 1 year preceding onset or exacerbation of skin disease. In the psoriasis vulgaris group, the most common stressful life event seen was financial loss or problems (8%), followed by death of close family member (4%), sexual problems (4%), family conflict (2%), major personal illness or injury (2%), and transfer or change in working conditions (2%), failure in examinations (2%), family member unemployed (2%), illness of family member (2%), getting married or engaged (2%), miscellaneous (2%). In the chronic urticaria group, the most common stressful life event seen was death of a close family member (6%), followed by family conflict (2%), financial loss or problems (2%), sexual problems (2%), illness of family member (2%), getting married or engaged (2%), trouble at work with colleagues, superiors, or subordinates (2%), going on a pleasure trip (2%) and extramarital relations (2%). Psychological stress plays a significant role in triggering or exacerbating dermatological diseases. Our study indicates the role of relaxation therapies and stress management programs in chronic diseases such as psoriasis and chronic urticaria. Psychological interventions can

  5. Lyapunov exponents a tool to explore complex dynamics

    CERN Document Server

    Pikovsky, Arkady

    2016-01-01

    Lyapunov exponents lie at the heart of chaos theory, and are widely used in studies of complex dynamics. Utilising a pragmatic, physical approach, this self-contained book provides a comprehensive description of the concept. Beginning with the basic properties and numerical methods, it then guides readers through to the most recent advances in applications to complex systems. Practical algorithms are thoroughly reviewed and their performance is discussed, while a broad set of examples illustrate the wide range of potential applications. The description of various numerical and analytical techniques for the computation of Lyapunov exponents offers an extensive array of tools for the characterization of phenomena such as synchronization, weak and global chaos in low and high-dimensional set-ups, and localization. This text equips readers with all the investigative expertise needed to fully explore the dynamical properties of complex systems, making it ideal for both graduate students and experienced researchers...

  6. Estimation of Hurst Exponent for the Financial Time Series

    Science.gov (United States)

    Kumar, J.; Manchanda, P.

    2009-07-01

    Till recently statistical methods and Fourier analysis were employed to study fluctuations in stock markets in general and Indian stock market in particular. However current trend is to apply the concepts of wavelet methodology and Hurst exponent, see for example the work of Manchanda, J. Kumar and Siddiqi, Journal of the Frankline Institute 144 (2007), 613-636 and paper of Cajueiro and B. M. Tabak. Cajueiro and Tabak, Physica A, 2003, have checked the efficiency of emerging markets by computing Hurst component over a time window of 4 years of data. Our goal in the present paper is to understand the dynamics of the Indian stock market. We look for the persistency in the stock market through Hurst exponent and fractal dimension of time series data of BSE 100 and NIFTY 50.

  7. Accurate Monte Carlo critical exponents for Ising lattices

    Science.gov (United States)

    García, Jorge; Gonzalo, Julio A.

    2003-08-01

    A careful Monte Carlo investigation of the phase transition very close to the critical point ( T→ Tc, H→0) in relatively large d=3, s= {1}/{2} Ising lattices did produce critical exponents β3 D=0.3126(4)≅5/16, δ3 D-1=0.1997(4)≅1/5 and γ3 D=1.253(4)≅5/4. Our results indicate that, within experimental error, they are given by simple fractions corresponding to the linear interpolations between the respective two dimensional (Onsager) and four dimensional (mean field) critical exponents. An analysis of our inverse susceptibility data χ-1( T) vs. | T- Tc| shows that these data lead to a value of γ3 D compatible with γ‧= γ and Tc=4.51152(12), while γ values obtained recently by high and low temperature series expansions and renormalization group methods are not.

  8. Determination of critical exponents of inhomogeneous Gd films

    Energy Technology Data Exchange (ETDEWEB)

    Rosales-Rivera, A., E-mail: arosalesr@unal.edu.co [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Salazar, N.A. [Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales (Colombia); Hovorka, O.; Idigoras, O.; Berger, A. [CIC nanoGUNE Consolider, Tolosa Hiribidea 76, E-20018 Donostia-San Sebastian (Spain)

    2012-08-15

    The role of inhomogeneity on the critical behavior is studied for non-epitaxial Gd films. For this purpose, the film inhomogeneity was varied experimentally by annealing otherwise identical samples at different temperatures T{sub AN}=200, 400, and 500 Degree-Sign C. Vibrating sample magnetometry (VSM) was used for magnetization M vs. T measurements at different external fields H. A method based upon the linear superposition of different sample parts having different Curie temperatures T{sub C} was used to extract the critical exponents and the intrinsic distribution of Curie temperatures. We found that this method allows extracting reliable values of the critical exponents for all annealing temperatures, which enabled us to study the effects of disorder onto the universality class of Gd films.

  9. Scaling exponents for fracture surfaces in opal glass

    Energy Technology Data Exchange (ETDEWEB)

    Chavez-Guerrero, L., E-mail: guerreroleo@hotmail.com [Facultad de Ingenieria Mecanica y Electrica. Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Center of Innovation, Research and Development on Engineering and Technology, Universidad Autonoma de Nuevo Leon Monterrey, C.P. 66600, Apodaca, Nuevo Leon (Mexico); Garza, F.J., E-mail: fjgarza@gama.fime.uanl.mx [Facultad de Ciencias Quimicas, Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Hinojosa, M., E-mail: hinojosa@gama.fime.uanl.mx [Facultad de Ingenieria Mecanica y Electrica. Cd. Universitaria s/n, C.P. 66450, Universidad Autonoma de Nuevo Leon, Nuevo Leon (Mexico); Center of Innovation, Research and Development on Engineering and Technology, Universidad Autonoma de Nuevo Leon Monterrey, C.P. 66600, Apodaca, Nuevo Leon (Mexico)

    2010-09-25

    We have investigated the scaling properties of fracture surfaces in opal glass. Specimens with two different opacifying particle sizes (1 {mu}m and 0.4 {mu}m) were broken by three-point bending test and the resulting fracture surfaces were analyzed using Atomic Force Microscopy. The analysis of the self-affine behavior was performed using the Variable Bandwidth and Height-Height Correlation Methods, and both the roughness exponent, {zeta}, and the correlation length, {xi}, were determined. It was found that the roughness exponent obtained in both samples is {zeta} {approx} 0.8; whereas the correlation length in both fractures is of the order of the particle size, demonstrating the dependence of this self-affine parameter on the microstructure of opal glass.

  10. Lyapunov exponents for complex systems with delayed feedback

    CERN Document Server

    Dailyudenko, V F

    2003-01-01

    Analytical and numerical analysis is implemented for two methods of Lyapunov exponents calculation. The first is based on successive multiplication of functional matrixes corresponding to discrete transformations and calculation of eigenvalues for the obtained matrix. The second approach is based on successive orthogonalization of multiplied matrixes using QR-decomposition. The analytical model for describing functional maps of discrete iterations derived from delay differential equation is proposed, which implements representation of the product matrix through matrixes of canonical form that reduces calculation complexity.

  11. Clustering of Casablanca stock market based on hurst exponent estimates

    Science.gov (United States)

    Lahmiri, Salim

    2016-08-01

    This paper deals with the problem of Casablanca Stock Exchange (CSE) topology modeling as a complex network during three different market regimes: general trend characterized by ups and downs, increasing trend, and decreasing trend. In particular, a set of seven different Hurst exponent estimates are used to characterize long-range dependence in each industrial sector generating process. They are employed in conjunction with hierarchical clustering approach to examine the co-movements of the Casablanca Stock Exchange industrial sectors. The purpose is to investigate whether cluster structures are similar across variable, increasing and decreasing regimes. It is observed that the general structure of the CSE topology has been considerably changed over 2009 (variable regime), 2010 (increasing regime), and 2011 (decreasing regime) time periods. The most important findings follow. First, in general a high value of Hurst exponent is associated to a variable regime and a small one to a decreasing regime. In addition, Hurst estimates during increasing regime are higher than those of a decreasing regime. Second, correlations between estimated Hurst exponent vectors of industrial sectors increase when Casablanca stock exchange follows an upward regime, whilst they decrease when the overall market follows a downward regime.

  12. Quantum Lyapunov Exponent of an Atomic Kicked Rotor

    Science.gov (United States)

    Galitski, Victor

    2017-04-01

    One of the most intriguing phenomena in the studies of classical chaos is the butterfly effect, which manifests itself in that small changes in initial conditions lead to drastically different trajectories. It is characterized by a Lyapunov exponent that measures divergence of the classical trajectories. The question how/if this prototypical effect of classical chaos theory generalizes to quantum systems (where the notion of a trajectory is undefined) has been of interest for decades, but became more popular recently, when it was realized that there exist intriguing connections to string theory and general relativity in some quantum chaotic models. At the center of this activity is the so-called out-of-time-ordered correlator (OTOC) - a quantity that in the classical limit seems to approximate the classical Lyapunov correlator. However, there are very few solvable models where one can actually calculate Lyapunov exponent and/or OTOC. In this talk, I will discuss the standard model of quantum and classical chaos - kicked rotor - calculate the correlator and Lypunov exponents, and show how classical chaos and Lyapunov divergence develop and cross-over to the quantum regime. We will see that the quantum out-of-time-ordered correlator exhibits a clear singularity at the Ehrenfest time, when quantum interference effects sharply kick in: transitioning from a time-independent value to its monotonous decrease with time. In conclusion, I will discuss possible experimental realizations of the model and predicted phenomena in ultracold quantum kicked rotors. NSF-DMR 1613029 and US-ARO.

  13. Nonlinearly charged Lifshitz black holes for any exponent z>1

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, Abigail; Ayón-Beato, Eloy [Departamento de Física, CINVESTAV-IPN, A.P. 14-740, 07000, México D.F. (Mexico); Instituto de Ciencias Físicas y Matemáticas, Universidad Austral de Chile,Valdivia (Chile); González, Hernán A. [Physique Théorique et Mathématique,Université Libre de Bruxelles & International Solvay Institutes,Campus Plaine C.P. 231, B-1050 Bruxelles (Belgium); Hassaïne, Mokhtar [Instituto de Matemática y Física, Universidad de Talca,Casilla 747, Talca (Chile)

    2014-06-09

    Charged Lifshitz black holes for the Einstein-Proca-Maxwell system with a negative cosmological constant in arbitrary dimension D are known only if the dynamical critical exponent is fixed as z=2(D−2). In the present work, we show that these configurations can be extended to much more general charged black holes which in addition exist for any value of the dynamical exponent z>1 by considering a nonlinear electrodynamics instead of the Maxwell theory. More precisely, we introduce a two-parametric nonlinear electrodynamics defined in the more general, but less known, so-called (H,P)-formalism and obtain a family of charged black hole solutions depending on two parameters. We also remark that the value of the dynamical exponent z=D−2 turns out to be critical in the sense that it yields asymptotically Lifshitz black holes with logarithmic decay supported by a particular logarithmic electrodynamics. All these configurations include extremal Lifshitz black holes. Charged topological Lifshitz black holes are also shown to emerge by slightly generalizing the proposed electrodynamics.

  14. Meteoroid stream flux densities and the zenith exponent

    Science.gov (United States)

    Molau, Sirko; Barentsen, Geert

    2013-01-01

    The MetRec software was recently extended to measure the limiting magnitude in real-time, and to determine meteoroid stream flux densities. This paper gives a short overview of the applied algorithms. We introduce the MetRec Flux Viewer, a web tool to visualize activity profiles on- line. Starting from the Lyrids 2011, high-quality flux density profiles were derived from IMO Video Network observations for every major meteor shower. They are often in good agreement with visual data. Analyzing the 2011 Perseids, we found systematic daily variations in the flux density profile, which can be attributed to a zenith exponent gamma > 1.0. We analyzed a number of meteor showers in detail and found zenith exponent variations from shower to shower in the range between 1.55 and 2.0. The average value over all analyzed showers is gamma = 1.75. In order to determine the zenith exponent precisely, the observations must cover a large altitude range (at least 45 degrees).

  15. The stressful life events schedule for children and adolescents: development and validation.

    Science.gov (United States)

    Williamson, Douglas E; Birmaher, Boris; Ryan, Neal D; Shiffrin, Tiffany P; Lusky, Jennifer A; Protopapa, Julie; Dahl, Ronald E; Brent, David A

    2003-08-01

    The development and psychometric properties of the Stressful Life Events Schedule (SLES), an interview instrument to assess stressors in children and adolescents, are described. Children (12 years) with psychopathology (n=30) and non-psychiatric controls (n=30) were interviewed with the SLES about the occurrence of stressful life events during the prior year. To examine concurrent validity of the SLES, all subjects also completed the self-report Life Events Checklist (LEC) and half the sample completed the Life Events and Difficulties Schedule (LEDS). To examine informant validity, the parent/guardian also reported on stressful life events occurring to their child during the year prior to interview. Test-retest reliability of the SLES was examined by re-assessing all children approximately one week after the initial interview. Subjects rated subjectively how stressful an event was on a 4-point scale. Additionally, panel ratings of objective stress and behavior-dependence/independence were made on 4-point scales. The SLES was found to have substantial inter-rater consensus reliability for objective threat (kappa=0.67) and almost perfect reliability for event behavior-dependence/independence (kappa=0.84). Similarly, the test-retest reliability of the SLES was also found to be substantial at the level of specific event comparisons (kappa=0.68). The SLES discriminated between children with and without psychopathology on all measures of stressful life events. Total stressful life events assessed with the SLES concurred well with those assessed by the LEC (ICC=0.83) and the LEDS (kappa=0.77) although, as expected, examination of specific events showed much smaller overlap between the SLES and the LEC (kappa=0.26). Child-parent agreement for the occurrence of severe events was substantial (kappa=0.73) but tended to be only moderate when all events were examined (kappa=0.48). The results of this study indicate that the SLES has good psychometric properties. The SLES is a

  16. Expressions for the Evaporation and Condensation Coefficients in the Hertz-Knudsen Relation.

    Science.gov (United States)

    Persad, Aaron H; Ward, Charles A

    2016-07-27

    Although the Hertz-Knudsen (HK) relation is often used to correlate evaporation data, the relation contains two empirical parameters (the evaporation and condensation coefficients) that have inexplicably been found to span 3 orders of magnitude. Explicit expressions for these coefficients have yet to be determined. This review will examine sources of error in the HK relation that have led to the coefficients' scatter. Through an examination of theoretical, experimental, and molecular dynamics simulation studies of evaporation, this review will show that the HK relation is incomplete, since it is missing an important physical concept: the coupling between the vapor and liquid phases during evaporation. The review also examines a modified HK relation, obtained from the quantum-mechanically based statistical rate theory (SRT) expression for the evaporation flux and applying a limit to it in which the thermal energy is dominant. Explicit expressions for the evaporation and condensation coefficients are defined in this limit, with the surprising result that the coefficients are not bounded by unity. An examination is made with 127 reported evaporation experiments of water and of ethanol, leading to a new physical interpretation of the coefficients. The review concludes by showing how seemingly small simplifications, such as assuming thermal equilibrium across the liquid-vapor interface during evaporation, can lead to the erroneous predictions from the HK relation that have been reported in the literature.

  17. The doping concentration and physical properties measurement of silicon water using tera hertz wave

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Hyeon; Oh, Gyung Hwan; Kim, Hak Sung [Dept. of Mechanical Convergence Engineering, Hanyang University, Seoul(Korea, Republic of)

    2017-02-15

    In this study, a tera hertz time domain spectroscopy (THz-TDS) imaging technique was used to measure doping concentration and physical properties (such as refractive index and permittivity) of the doped silicon (Si) wafers. The transmission and reflection modes with an incidence angle of 30° were employed to determine the physical properties of the doped Si wafers. The doping concentrations of the prepared Si wafers were varied from 10{sup 14} to 10{sup 18} in both N-type and P-type cases. Finally, the correlation between the doping concentration and the power of the THz wave was determined by measuring the powers of the transmitted and reflected THz waves of the doped Si wafers. Additionally, the doped thickness, the refractive index, and permittivity of each doped Si wafer were calculated using the THz time domain waveform. The results indicate that the THz-TDS imaging technique is potentially a promising technique to measure the doping concentration as well as other optical properties (such as the refractive index and permittivity) of the doped Si wafer.

  18. Automation of the Franck-Hertz experiment and the Tel-X-Ometer x-ray machine using LABVIEW

    Science.gov (United States)

    Fedak, W.; Bord, D.; Smith, C.; Gawrych, D.; Lindeman, K.

    2003-05-01

    We describe the use of LABVIEW to automate data collection and instrument control for the Franck-Hertz experiment and for the popular Tel-X-Ometer x-ray machine. Such automation permits the rapid collection and reduction of large amounts of data, thus facilitating exploration of the basic physics of these experiments. The use of industry-standard software packages, such as ORIGIN and MATHEMATICA, provides students with valuable exposure to professional tools for the display and analysis of data.

  19. Stressful Life Events and Depression Symptoms: The Effect of Childhood Emotional Abuse on Stress Reactivity

    Science.gov (United States)

    Shapero, Benjamin G.; Black, Shimrit K.; Liu, Richard T.; Klugman, Joshua; Bender, Rachel E.; Abramson, Lyn Y.; Alloy, Lauren B.

    2013-01-01

    Objective Stressful life events are associated with an increase in depressive symptoms and the onset of major depression. Importantly, research has shown that the role of stress changes over the course of depression. The present study extends the current literature by examining the effects of early life stress on emotional reactivity to current stressors. Method In a multiwave study (N = 281, mean age = 18.76; 68% female), we investigated the proximal changes that occur in depressive symptoms when individuals are faced with life stress and whether a history of childhood emotional abuse moderates this relationship. Results Results support the stress sensitivity hypothesis for early emotional abuse history. Individuals with greater childhood emotional abuse severity experienced greater increases in depressive symptoms when confronted with current dependent stressors, controlling for childhood physical and sexual abuse. Conclusions This study highlights the importance of emotional abuse as an indicator for reactivity to stressful life events. PMID:23800893

  20. Stressful life events and depression symptoms: the effect of childhood emotional abuse on stress reactivity.

    Science.gov (United States)

    Shapero, Benjamin G; Black, Shimrit K; Liu, Richard T; Klugman, Joshua; Bender, Rachel E; Abramson, Lyn Y; Alloy, Lauren B

    2014-03-01

    Stressful life events are associated with an increase in depressive symptoms and the onset of major depression. Importantly, research has shown that the role of stress changes over the course of depression. The present study extends the current literature by examining the effects of early life stress on emotional reactivity to current stressors. In a multiwave study (N = 281, mean age = 18.76; 68% female), we investigated the proximal changes that occur in depressive symptoms when individuals are faced with life stress and whether a history of childhood emotional abuse moderates this relationship. Results support the stress sensitivity hypothesis for early emotional abuse history. Individuals with greater childhood emotional abuse severity experienced greater increases in depressive symptoms when confronted with current dependent stressors, controlling for childhood physical and sexual abuse. This study highlights the importance of emotional abuse as an indicator for reactivity to stressful life events. © 2013 Wiley Periodicals, Inc.

  1. Cumulative Impact of Stressful Life Events on the Development of Takotsubo Cardiomyopathy.

    Science.gov (United States)

    Rosman, Lindsey; Dunsiger, Shira; Salmoirago-Blotcher, Elena

    2017-12-01

    The role of stressful life events in the onset of Takotsubo cardiomyopathy (TC) is unclear. This study sought to examine associations between type, timing, and number of stressful life events and onset of TC. A case-control study conducted among consecutive incident female TC cases and myocardial infarction (MI) controls admitted to two emergency departments in New England. Healthy female controls (HC) were recruited from a volunteers' registry. Information about the timing, type, and number of triggers during the 6 months preceding hospitalization was systematically collected using the PERI Life Events Scale about 1 month post-discharge. Group differences were evaluated using ANOVA, chi-square, and Kruskal-Wallis statistics. Generalized linear models were used to adjust for confounding variables. Between March 2013 and October 2015, 107 women were enrolled (45 TC, 32 MI, and 30 HC). Specific stressful events (death of a relative or close friend (p = 0.006); illness or injury to a relative or close friend (p = 0.001) were more prevalent in TC cases than MI and HC controls. The onset of TC was associated with exposure to multiple stressful life events during the 6 months preceding the index hospitalization (p < 0.001) but not with exposure to an acute, recent event (p = 0.96). TC onset was associated with specific life events (death or illness to close relative or friend) and with the number of stressful life events occurring in the 6 months preceding hospitalization. These findings suggest that grief and cumulative stress could play a major role in the onset of TC.

  2. Psychological distress and stressful life events in pediatric complex regional pain syndrome

    OpenAIRE

    Julia Wager; Hannah Brehmer; Gerrit Hirschfeld; Boris Zernikow

    2015-01-01

    BACKGROUND: There is little knowledge regarding the association between psychological factors and complex regional pain syndrome (CRPS) in children. Specifically, it is not known which factors precipitate CRPS and which result from the ongoing painful disease. OBJECTIVES: To examine symptoms of depression and anxiety as well as the experience of stressful life events in children with CRPS compared with children with chronic primary headaches and functional abdominal pain. METHODS: A retrospec...

  3. Green space as a buffer between stressful life events and health.

    Science.gov (United States)

    van den Berg, Agnes E; Maas, Jolanda; Verheij, Robert A; Groenewegen, Peter P

    2010-04-01

    This study investigates whether the presence of green space can attenuate negative health impacts of stressful life events. Individual-level data on health and socio-demographic characteristics were drawn from a representative two-stage sample of 4529 Dutch respondents to the second Dutch National Survey of General Practice (DNSGP-2), conducted in 2000-2002. Health measures included: (1) the number of health complaints in the last 14 days; (2) perceived mental health (measured by the GHQ-12); and (3) a single item measure of perceived general health ranging from 'excellent' to 'poor'. Percentages of green space in a 1-km and 3-km radius around the home were derived from the 2001 National Land cover Classification database (LGN4). Data were analysed using multilevel regression analysis, with GP practices as the group-level units. All analyses were controlled for age, gender, income, education level, and level of urbanity. The results show that the relationships of stressful life events with number of health complaints and perceived general health were significantly moderated by amount of green space in a 3-km radius. Respondents with a high amount of green space in a 3-km radius were less affected by experiencing a stressful life event than respondents with a low amount of green space in this radius. The same pattern was observed for perceived mental health, although it was marginally significant. The moderating effects of green space were found only for green space within 3 km, and not for green space within 1 km of residents' homes, presumably because the 3-km indicator is more affected by the presence of larger areas of green space, that are supposed to sustain deeper forms of restoration. These results support the notion that green space can provide a buffer against the negative health impact of stressful life events. Copyright 2010 Elsevier Ltd. All rights reserved.

  4. Role of stressful life events in induction or exacerbation of psoriasis and chronic urticaria

    OpenAIRE

    Malhotra S; Mehta Vivek

    2008-01-01

    Background: The possibility of a causal influence of emotional stress, especially of stressful life events, on the course of various skin diseases has long been postulated. Previous reports addressing its influence on skin psoriasis and chronic urticaria have been mainly anecdotal. Objective: The aim of this study was to evaluate the stressful events of life within 1 year preceding onset or exacerbation of skin disease in patients of psoriasis vulgaris and chronic urticaria. Method: Fif...

  5. Role of stressful life events and kindling in bipolar disorder: Converging evidence from a mania-predominant illness course.

    Science.gov (United States)

    Subramanian, Karthick; Sarkar, Siddharth; Kattimani, Shivanand; Philip Rajkumar, Ravi; Penchilaiya, Venkatalakshmi

    2017-12-01

    Stressful life events can precipitate relapses and recurrences in bipolar disorder. Kindling in bipolar disorder has been linked to maladaptive psychological reactivity to minor stressful life events. Systematic studies on life events and kindling are rare in bipolar disorder with a manic predominant polarity. One hundred and forty-nine remitted patients with bipolar I disorder were recruited. The National Institute of Mental Health-Life Chart Methodology was used to depict the illness course retrospectively, and the Presumptive Stressful Life Events Scale-Lifetime version was used to record the stressful life events. The role of stressful life events and the probability of kindling were assessed using appropriate statistics. There was a mania-predominant course of bipolar disorder in the sample with 55.7% (n = 83) having only recurrent mania. Family conflict and altered sleep patterns were the commonly reported stressful life events. When controlled for the severity of the stressor, the stressful life events were often associated with the initial episodes rather than the latter ones. Kindling may occur in bipolar disorder with mania as the predominant polarity. However, retrospective recall bias and hospital-based sampling limit generalizability of such observations. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Stressful Life Events and Child Anxiety: Examining Parent and Child Mediators.

    Science.gov (United States)

    Platt, Rheanna; Williams, Sarah R; Ginsburg, Golda S

    2016-02-01

    While a number of factors have been linked with excessive anxiety (e.g., parenting, child temperament), the impact of stressful life events remains under-studied. Moreover, much of this literature has examined bivariate associations rather than testing more complex theoretical models. The current study extends the literature on life events and child anxiety by testing a theory-driven meditational model. Specifically, one child factor (child cognitions/locus of control), two parent factors (parent psychopathology and parenting stress), and two parent-child relationship factors (parent-child dysfunctional interaction and parenting style) were examined as mediators in the relationship between stressful life events and severity of child anxiety. One hundred and thirty anxious parents and their nonanxious, high-risk children (ages ranged from 7 to 13 years) participated in this study. Results indicated that levels of parenting stress, parental anxious rearing, and dysfunctional parent-child interaction mediated the association between stressful life events and severity of anxiety symptoms. Child cognition and parent psychopathology factors failed to emerge as mediators. Findings provide support for more complex theoretical models linking life events and child anxiety and suggest potential targets of intervention.

  7. Stressful Life Events and Child Anxiety: Examining Parent and Child Mediators

    Science.gov (United States)

    Platt, Rheanna; Williams, Sarah R.; Ginsburg, Golda S.

    2015-01-01

    While a number of factors have been linked with excessive anxiety (e.g., parenting, child temperament), the impact of stressful life events remains under-studied. Moreover, much of this literature has examined bivariate associations rather than testing more complex theoretical models. The current study extends the literature on life events and child anxiety by testing a theory-driven meditational model. Specifically, one child factor (child cognitions/locus of control), two parent factors (parent psychopathology and parenting stress), and two parent-child relationship factors (parent-child dysfunctional interaction and parenting style) were examined as mediators in the relationship between stressful life events and severity of child anxiety. One hundred and thirty anxious parents and their nonanxious, high-risk children (ages ranged from 7 to 13 years) participated in this study. Results indicated that levels of parenting stress, parental anxious rearing, and dysfunctional parent-child interaction mediated the association between stressful life events and severity of anxiety symptoms. Child cognition and parent psychopathology factors failed to emerge as mediators. Findings provide support for more complex theoretical models linking life events and child anxiety and suggest potential targets of intervention. PMID:25772523

  8. Stressful life events, family support and successful ageing in the Biafran War generation.

    Science.gov (United States)

    Chukwuorji, JohnBosco Chika; Nwoke, Mary Basil; Ebere, Magnus Okechukwu

    2017-01-01

    Although the developing countries contribute substantially to the population of the elderly, little is known about ageing in populous countries like Nigeria, particularly the Biafran War generation (BWG). Some of those who witnessed the Biafran War (also known as Nigerian Civil War) as children are well into late adulthood, while the majority of this pre-war/wartime cohort who are in their golden years will enter into later life in less than a decade from now. The aim of the present research was to examine the role of stressful life events and family support in successful ageing of the BWG. Data were collected using a self-administered survey completed by 453 members of the BWG who were ≥45 years. The survey included measures such as the Successful Ageing Inventory, Life Events Inventory, and family support subscale of Family Dynamics Scale. Hierarchical multiple regression analyses were conducted to test the hypotheses of the study. The three dimensions of stressful life events (health events, interpersonal events and work-related/financial events) had moderate negative relationships with successful ageing. Family support was moderately and positively associated with successful ageing. For the moderation hypotheses, family support was a significant moderator of only the relationship between work-related stressful life events and successful ageing, especially for the Family support provides social protection for older people, in the face of difficult socio-economic circumstances.

  9. Stressful life events and adolescent substance use and depression: conditional and gender differentiated effects.

    Science.gov (United States)

    Hoffmann, J P; Su, S S

    1998-09-01

    Stressful life circumstances have myriad influences on human health and behavior. Early research focused on the variable distribution of stress and its effects by socioeconomic status, race, and gender. More recent research indicates that variation by age is also an important consideration. For example, adolescent reactions to stressful life events are often inconsistent with adult reactions to similar life situations and transitions. Moreover, since most studies assess only a single outcome--usually depression--they risk classification bias since analyses exclude other potential stress-related outcomes. This paper assesses the gender distinct effects of stressful life events on two outcomes among adolescents, substance use and depressive symptoms. The results of a second-order regression model indicate that life events affect female, but not male, depressive symptoms, especially when self-esteem is low or mastery is high. Furthermore, life events affect substance use when peer drug use is high, or when parental support is low, but this latter effect is limited to female adolescents.

  10. Universal scaling in disordered systems and nonuniversal exponents

    Science.gov (United States)

    Bardhan, K. K.; Talukdar, D.; Nandi, U. N.; Mukherjee, C. D.

    2014-05-01

    The effect of an electric field on conduction in a disordered system is an old but largely unsolved problem. Experiments cover a wide variety of systems—amorphous/doped semiconductors, conducting polymers, organic crystals, manganites, composites, metallic alloys, double perovskites—ranging from strongly to weakly localized systems and from strongly to weakly correlated ones. Theories have singularly failed to predict any universal trend resulting in separate theories for separate systems. Here, we discuss a one-parameter scaling that has recently been found to give a systematic account of the field-dependent conductance in two diverse, strongly localized systems of conducting polymers and manganites. Except for a limited number of systems which are described by the hot electron models, the vast majority of different systems in various disorder regimes in two (2D)- and three (2D)-dimensions obey the scaling. The nonlinearity exponent x associated with the scaling was found to be nonuniversal and exhibiting a structure. For 2D weakly localized systems, the nonlinearity exponent x is ≥7 and is roughly inversely proportional to the sheet resistance. The existing theories of weak localization prove to be adequate and a complete scaling function is derived. In a 2D strongly localized system, a temperature-induced scaling-nonscaling transition (SNST) is revealed. For 3D strongly localized systems, the exponent lies between -1 and 1, and surprisingly is quantized (x ≈0.08n). This poses a serious theoretical challenge. Various results are compared with predictions of the existing theories.

  11. Fatigue crack shape prediction based on the stress singularity exponent

    Czech Academy of Sciences Publication Activity Database

    Hutař, Pavel; Ševčík, Martin; Náhlík, Luboš; Knésl, Zdeněk

    488-489, č. 1 (2012), s. 178-181 ISSN 1013-9826. [International Conference on Fracture and Damage Mechanics - FDM 2011 /10./. Dubrovník, 19.09.2011-21.09.2011] R&D Projects: GA ČR GA101/09/0867 Grant - others:GA AV ČR(CZ) M100420901 Institutional research plan: CEZ:AV0Z2041904 Keywords : stress singularity exponent * crack front curvature * vertex singularity * free surface effect Subject RIV: JL - Materials Fatigue, Friction Mechanics

  12. Maxwell, Hertz and Marconi, using the history of science and technology in science education

    Science.gov (United States)

    Zito, Fredrick Anthony

    This dissertation examines the possibility of using a Kuhnian framework to enhance the use of history in the teaching of science. The Kuhnian framework of "revolutionary" and "normal" science, it is noted, provides a simplifying yet explanatory framework for students of science, at the same time making it possible to show the daily life of scientists. Rather than focus only on heroes of science, the work examines the important work of the "normal" scientist and their interplay with "revolutionary" scientists. It is argued that seeing the daily life of the scientist within this framework can show students of science the profound impact of the seemingly simple contributions of the work of scientists. In addition, it is noted that viewing the history of science as shifting paradigms and scientific revolutions will not only enhance students' scientific literacy, but possibly enhance their willingness to pursue science education. A review of the theoretical literature surrounding Kuhn, his followers and his critics, suggest the framework is still salient among educators. A review of the empirical literature and some educational practices suggests that educators see this approach to be effective, especially when the framework and case materials are carefully crafted. The empirical literature also suggests that there is a gap between the prescribed standards (national and state) for teaching the history of science, and actual classroom practice. The Kuhnian framework shows promise for bridging this gap. The dissertation then uses a case history of the discovery of electromagnetic radiation by Faraday, Maxwell, and Hertz et al., culminating in the development wireless telegraphy by Marconi, making possible radio, television, radar, and other contemporary technologies. The dissertation concludes by noting that the use of history as an arena for understanding science, in some way resembles the concept of "reflective thinking", which is often utilized as a framework for

  13. Studies on omnidirectional enhancement of giga-hertz radiation by sub-wavelength plasma modulation

    Science.gov (United States)

    Fanrong, KONG; Qiuyue, NIE; Shu, LIN; Zhibin, WANG; Bowen, LI; Shulei, ZHENG; Binhao, JIANG

    2018-01-01

    The technology of radio frequency (RF) radiation intensification for radio compact antennas based on modulation and enhancement effects of sub-wavelength plasma structures represents an innovative developing strategy. It exhibits important scientific significance and promising potential of broad applications in various areas of national strategic demands, such as electrical information network and microwave communication, detection and control technology. In this paper, laboratory experiments and corresponding analyses have been carried out to investigate the modulation and enhancement technology of sub-wavelength plasma structure on the RF electromagnetic radiation. An application focused sub-wavelength plasma-added intensification up to ∼7 dB higher than the free-space radiation is observed experimentally in giga-hertz (GHz) RF band. The effective radiation enhancement bandwidth covers from 0.85 to 1.17 GHz, while the enhanced electromagnetic signals transmitted by sub-wavelength plasma structures maintain good communication quality. Particularly, differing from the traditional RF electromagnetic radiation enhancement method characterized by focusing the radiation field of antenna in a specific direction, the sub-wavelength plasma-added intensification of the antenna radiation presents an omnidirectional enhancement, which is reported experimentally for the first time. Corresponding performance characteristics and enhancement mechanism analyses are also conducted in this paper. The results have demonstrated the feasibility and promising potential of sub-wavelength plasma modulation in application focused RF communication, and provided the scientific basis for further research and development of sub-wavelength plasma enhanced compact antennas with wide-range requests and good quality for communication.

  14. Non-trivial rheological exponents in sheared yield stress fluids.

    Science.gov (United States)

    Agoritsas, Elisabeth; Martens, Kirsten

    2017-07-14

    In this work we discuss possible physical origins of non-trivial exponents in the athermal rheology of soft materials at low but finite driving rates. A key ingredient in our scenario is the presence of a self-consistent mechanical noise that stems from the spatial superposition of long-range elastic responses to localized plastically deforming regions. We study analytically a mean-field model, in which this mechanical noise is accounted for by a stress diffusion term coupled to the plastic activity. Within this description we show how a dependence of the shear modulus and/or the local relaxation time on the shear rate introduces corrections to the usual mean-field prediction, concerning the Herschel-Bulkley-type rheological response of exponent 1/2. This feature of the mean-field picture is then shown to be robust with respect to structural disorder and partial relaxation of the local stress. We test this prediction numerically on a mesoscopic lattice model that implements explicitly the long-range elastic response to localized shear transformations, and we conclude on how our scenario might be tested in rheological experiments.

  15. Pixel classification based color image segmentation using quaternion exponent moments.

    Science.gov (United States)

    Wang, Xiang-Yang; Wu, Zhi-Fang; Chen, Liang; Zheng, Hong-Liang; Yang, Hong-Ying

    2016-02-01

    Image segmentation remains an important, but hard-to-solve, problem since it appears to be application dependent with usually no a priori information available regarding the image structure. In recent years, many image segmentation algorithms have been developed, but they are often very complex and some undesired results occur frequently. In this paper, we propose a pixel classification based color image segmentation using quaternion exponent moments. Firstly, the pixel-level image feature is extracted based on quaternion exponent moments (QEMs), which can capture effectively the image pixel content by considering the correlation between different color channels. Then, the pixel-level image feature is used as input of twin support vector machines (TSVM) classifier, and the TSVM model is trained by selecting the training samples with Arimoto entropy thresholding. Finally, the color image is segmented with the trained TSVM model. The proposed scheme has the following advantages: (1) the effective QEMs is introduced to describe color image pixel content, which considers the correlation between different color channels, (2) the excellent TSVM classifier is utilized, which has lower computation time and higher classification accuracy. Experimental results show that our proposed method has very promising segmentation performance compared with the state-of-the-art segmentation approaches recently proposed in the literature. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Truncatable bootstrap equations in algebraic form and critical surface exponents

    Energy Technology Data Exchange (ETDEWEB)

    Gliozzi, Ferdinando [Dipartimento di Fisica, Università di Torino andIstituto Nazionale di Fisica Nucleare - sezione di Torino,Via P. Giuria 1, Torino, I-10125 (Italy)

    2016-10-10

    We describe examples of drastic truncations of conformal bootstrap equations encoding much more information than that obtained by a direct numerical approach. A three-term truncation of the four point function of a free scalar in any space dimensions provides algebraic identities among conformal block derivatives which generate the exact spectrum of the infinitely many primary operators contributing to it. In boundary conformal field theories, we point out that the appearance of free parameters in the solutions of bootstrap equations is not an artifact of truncations, rather it reflects a physical property of permeable conformal interfaces which are described by the same equations. Surface transitions correspond to isolated points in the parameter space. We are able to locate them in the case of 3d Ising model, thanks to a useful algebraic form of 3d boundary bootstrap equations. It turns out that the low-lying spectra of the surface operators in the ordinary and the special transitions of 3d Ising model form two different solutions of the same polynomial equation. Their interplay yields an estimate of the surface renormalization group exponents, y{sub h}=0.72558(18) for the ordinary universality class and y{sub h}=1.646(2) for the special universality class, which compare well with the most recent Monte Carlo calculations. Estimates of other surface exponents as well as OPE coefficients are also obtained.

  17. Entropies and Scaling Exponents of Street and Fracture Networks

    Directory of Open Access Journals (Sweden)

    Agust Gudmundsson

    2012-04-01

    Full Text Available Many natural and man-made lineaments form networks that can be analysed through entropy and energy considerations. Here we report the results of a detailed study of the variations in trends and lengths of 1554 named streets and 6004 street segments, forming a part of the evolving street network of the city of Dundee in East Scotland. Based on changes in the scaling exponents (ranging from 0.24 to 3.89, the streets can be divided into 21 populations. For comparison, we analysed 221 active crustal fractures in Iceland that (a are of similar lengths as the streets of Dundee; (b are composed of segments; and (c form evolving networks. The streets and fractures follow power-law size distributions (validated through various statistical tests that can be partly explained in terms of the energies needed for their formation. The entropies of the 21 street populations and 9 fracture populations show strong linear correlations with (1 the scaling exponents (R2 = 0.845–0.947 for streets, R2 = 0.859 for fractures and with (2 the length ranges, that is, the differences between the longest and shortest streets/fractures, (R2 = 0.845–0.906 for streets, R2 = 0.927 for fractures.

  18. The association between stressful life events and depressive symptoms among Cypriot university students: a cross-sectional descriptive correlational study

    National Research Council Canada - National Science Library

    Sokratous, Sokratis; Merkouris, Anastasios; Middleton, Nicos; Karanikola, Maria

    2013-01-01

    .... A descriptive correlational design with cross sectional comparison was used. The CES-D scale was applied for the assessment of depressive symptoms and the LESS instrument for stressful life events...

  19. The relationship between glucocorticoid receptor polymorphisms, stressful life events, social support, and post-traumatic stress disorder.

    Science.gov (United States)

    Lian, Yulong; Xiao, Jing; Wang, Qian; Ning, Li; Guan, Suzhen; Ge, Hua; Li, Fuye; Liu, Jiwen

    2014-08-12

    It is debatable whether or not glucocorticoid receptor (GR) polymorphisms moderate susceptibility to PTSD. Our objective was to examine the effects of stressful life events, social support, GR genotypes, and gene-environment interactions on the etiology of PTSD. Three tag single nucleotide polymorphisms, trauma events, stressful life events, and social support were assessed in 460 patients with PTSD and 1158 control subjects from a Chinese Han population. Gene-environment interactions were analyzed by generalized multifactor dimensionality reduction (GMDR). Variation in GR at rs41423247 and rs258747, stressful life events, social support, and the number of traumatic events were each separately associated with the risk for PTSD. A gene-environment interaction among the polymorphisms, rs41423247 and rs258747, the number of traumatic events, stressful life events, and social support resulted in an increased risk for PTSD. High-risk individuals (a large number of traumatic events, G allele of rs258747 and rs41423247, high level stressful life events, and low social support) had a 3.26-fold increased risk of developing PTSD compared to low-risk individuals. The association was statistically significant in the sub-groups with and without childhood trauma. Our data support the notion that stressful life events, the number of trauma events, and social support may play a contributing role in the risk for PTSD by interacting with GR gene polymorphisms.

  20. [Gender differences in stressful life events and depression in Chinese adults aged 30-79 years].

    Science.gov (United States)

    Wu, M; Li, J C; Yu, C Q; Chen, Y P; Lyu, J; Guo, Y; Bian, Z; Tan, Y L; Pei, P; Chen, J S; Chen, Z M; Li, L M

    2017-11-10

    Objective: To investigate gender specific differences in the association between stressful life events (SLEs) and depression in Chinese adults aged 30-79 years. Methods: In the baseline survey during 2004-2008, the China Kadoorie Biobank (CKB) recruited 512 891 men and women aged 30-79 years from 10 areas of China. Detailed information on SLEs, including demographic and socio-economic status, smoking, alcohol drinking and history of chronic disease, as well as depression symptoms and major depressive episodes (MDEs) in preceding 12 months, was collected by using standardized questionnaire. Multinomial logistic regression model was employed to estimate the relative risk ratio (RRR) and 95%CI of SLEs (3 categories, 10 items) on depression and the dose-response relationship between the number of SLEs experienced and depression. The interactions between gender and SLEs on depression were examined with likelihood ratio test. Results: Among the 512 891 participants, 35 085 (6.8%) reported family-related events, 5 972 (1.2%) reported finance-related events, and 4 453 (0.9%) reported other stressful life events. Females had a higher occurrence of family-related events, while males had a higher occurrence of finance-related and other events (all P-value events showed stronger association in female (P for interaction 0.05). Furthermore, the effect of the number of SLEs experienced increased in a dose-response manner on depressive symptoms and MDEs for both genders, but no gender specific differences were found. Conclusions: The gender modifies the association between stressful life events and depression in Chinese adults, and women experienced family-related events have a greater risk of depression. The more the stressful events experienced, the more likely to have depression.

  1. Relation between stressful life events, neuropeptides and cytokines: results from the LISA birth cohort study.

    Science.gov (United States)

    Herberth, Gunda; Weber, Annegret; Röder, Stefan; Elvers, Horst-Dietrich; Krämer, Ursula; Schins, Roel P F; Diez, Ulrike; Borte, Michael; Heinrich, Joachim; Schäfer, Thomas; Herbarth, Olf; Lehmann, Irina

    2008-12-01

    Stressful life events evidently have an impact on development of allergic diseases, but the mechanism linking stress to pathological changes of immune system function is still not fully understood. The aim of our study was to investigate the relationship between stressful life events, neuropeptide and cytokine concentrations in children. Within the LISAplus (Life style-Immune system-Allergy) study, blood samples from children of 6 yr of age were analysed for concentration of the neuropeptides vasoactive intestinal peptide (VIP), somatostatin (SOM), substance P (SP) and the Th1/Th2 cytokines interferon-gamma (IFN-gamma) and interleukin (IL)-4. Life events such as severe disease or death of a family member, unemployment or divorce of the parents were assessed with a questionnaire filled in by the parents. For 234 children, blood analysis and questionnaire data regarding life events were available. Children with separated/divorced parents showed high VIP levels and high concentrations of the Th2 cytokine IL-4 in their blood. Severe diseases and death of a family member were neither associated with neuropeptide levels nor with cytokine concentrations. Unemployment of the parents was associated with decreased IFN-gamma concentrations in children's blood but not with neuropeptide levels, whereas children experiencing concomitant severe disease and death of a family member had reduced SP blood levels. The neuropeptide VIP might be a mediator between stressful life events and immune regulation contributing to the Th2 shifted immune response in children with separated/divorced parents. Unemployment of the parents was associated with immune regulation in children on the basis of a still unknown mechanism whereas reduced SP levels seem to have no effect on immune regulation.

  2. Major stressful life events in adulthood and risk of multiple sclerosis.

    Science.gov (United States)

    Nielsen, Nete Munk; Bager, Peter; Simonsen, Jacob; Hviid, Anders; Stenager, Egon; Brønnum-Hansen, Henrik; Koch-Henriksen, Nils; Frisch, Morten

    2014-10-01

    It is unclear whether psychological stress is associated with increased risk of multiple sclerosis (MS). We studied the association between major stressful life events and MS in a nationwide cohort study using death of a child or a spouse or marital dissolution as indicators of severe stress. We created two study cohorts based on all Danish men and women born 1950-1992. One cohort consisted of all persons who became parents between 1968 and 2010, and another cohort consisted of all persons who married between 1968 and 2010. Members of both cohorts were followed for MS between 1982 and 2010 using data from the National Multiple Sclerosis Registry. Associations between major stressful life events and risk of MS were evaluated by means of MS incidence rate ratios (RR) with 95% confidence interval (CI) obtained in Poisson regression analyses. During approximately 30 million person-years of follow-up, bereaved parents experienced no unusual risk of MS compared with parents who did not lose a child (RR=1.12 (95% CI 0.89 to 1.38)). Likewise, neither divorced (RR=0.98 (95% CI 0.89 to 1.06)) nor widowed (RR=0.98 (95% CI 0.71 to 1.32) persons were at any unusual risk of MS compared with married persons of the same sex. Our national cohort study provides little evidence for a causal association between major stressful life events (as exemplified by divorce or the loss of a child or a spouse) and subsequent MS risk. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  3. Stressful life events during pregnancy as risk factors for developing autistic disorder in children

    Directory of Open Access Journals (Sweden)

    Salman Abdi

    2016-12-01

    Full Text Available Introduction: This study aimed to examine the role of prenatal stressful events in mothers of children and adolescents with autistic disorder (AD. Methods: This case-control study was conducted in 2014. A total number of 115 children and adolescents with AD were selected by convenience method from the autism rehabilitation centers in Tabriz, Iran. Moreover, 112 typically developing (TD children and adolescents were selected from public schools using a random clustering method. Two groups were matched in terms of mother's and child's age and mother's educational level. The Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS semi-structured diagnostic interview was used to evaluate the presence of psychiatric disorders. The diagnosis of AD was made based on the DSM-IV criteria during separate diagnostic interviews by two child and adolescent psychiatrists. The life stressful events’ inventory was used to assess the presence of stressful events during pregnancy. Results: According to Fisher's exact test, the frequency of stressful life events including failure to achieve life goals, high debt, frequent marital conflict, conflict with spouse's family, changes in sleeping habits, and sexual difficulties in the mothers of AD children during pregnancy was significantly higher than the mothers of TD children. Also, mothers of AD children reported significantly higher frequency for the positive stressful life events including the major job progress, starting or finishing education, change of education, location, and summer vacation during pregnancy. Conclusion: Some stressful life events in mothers during pregnancy may be considered as risk factors for developing AD in their children. Further researches are needed to establish the results of this study.

  4. Skeleton graph expansion of critical exponents in "cultural revolution" years

    Science.gov (United States)

    Hao, Bailin

    Kenneth Wilson's Nobel Prize winning breakthrough in the renormalization group theory of phase transition and critical phenomena almost overlapped with the violent "cultural revolution" years (1966-1976) in China. An unexpected chance in 1972 brought the author of these lines close to the Wilson-Fisher є-expansion of critical exponents and eventually led to a joint paper with Lu Yu published entirely in Chinese without any English title and abstract. Even the original acknowledgment was deleted because of mentioning foreign names like Kenneth Wilson and Kerson Huang. In this article I will tell the 40-year old story as a much belated tribute to Kenneth Wilson and to reproduce the essence of our work in English. At the end, I give an elementary derivation of the Callan-Symanzik equation without referring to field theory.

  5. Nonuniversality of roughness exponent of quasistatic fracture surfaces.

    Science.gov (United States)

    Ansari-Rad, Mehdi; Allaei, S Mehdi Vaez; Sahimi, Muhammad

    2012-02-01

    Numerous experiments have indicated that the fracture front (in three dimensions) and crack lines (in two dimensions) in disordered solids and rocklike materials is rough. It has been argued that the roughness exponent ζ is universal. Using extensive simulations of a two-dimensional model, we provide strong evidence that if extended correlations and anisotropy-two features that are prevalent in many materials-are incorporated in the models that are used in the numerical simulation of crack propagation, then ζ will vary considerably with the extent of the correlations and anisotropy. The results are consistent with recent experiments that also indicate deviations of ζ from its supposedly universal value, as well as with the data from rock samples. © 2012 American Physical Society

  6. Computation of entropy and Lyapunov exponent by a shift transform

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, Chihiro, E-mail: matsuoka.chihiro.mm@ehime-u.ac.jp [Department of Physics, Graduate School of Science and Technology, Ehime University, Matsuyama, Ehime 790-8577 (Japan); Hiraide, Koichi [Department of Mathematics, Graduate School of Science and Technology, Ehime University, Matsuyama, Ehime 790-8577 (Japan)

    2015-10-15

    We present a novel computational method to estimate the topological entropy and Lyapunov exponent of nonlinear maps using a shift transform. Unlike the computation of periodic orbits or the symbolic dynamical approach by the Markov partition, the method presented here does not require any special techniques in computational and mathematical fields to calculate these quantities. In spite of its simplicity, our method can accurately capture not only the chaotic region but also the non-chaotic region (window region) such that it is important physically but the (Lebesgue) measure zero and usually hard to calculate or observe. Furthermore, it is shown that the Kolmogorov-Sinai entropy of the Sinai-Ruelle-Bowen measure (the physical measure) coincides with the topological entropy.

  7. Uncertainty exponents for chaotic particle scattering in the magnetotail

    Science.gov (United States)

    Presley, M.; Holland, D. L.; Martin, R. F.; Matsuoka, H.

    2009-12-01

    In chaotic scattering systems such as the magnetotial, small uncertainties in the initial conditions make it difficult to predict whether a given particle will be forward-scattered or back-scattered in its interaction with the field reversal. A particle with initial conditions x0, is said to be ɛ certain if all of the particles with initial conditions x such that |x - x0|proportional to ɛ. For fractal basin boundaries, f(ɛ) is proportional to ɛ^α where α=N-D0 is the uncertainty exponent, N is the dimension of the phase space and D0 is the box counting dimension of the basin boundary. For αmandates a reduction in ɛ by a factor of 10^(1/α) and thus there is a high level of sensitivity to the initial conditions, (a hallmark of chaos.) In this paper we have examine the uncertainty exponent for chaotic particles in the modified Harris model of the magnetotail as a function of both the energy and the normal component of the magnetic field. For each parameter set, we launching 1000 chaotic orbits from the asymptotic region and then follow four additional orbits whose initial conditions vary by ɛ. If all 5 initial conditions scatter in the same direction, the particle is ɛ certain. We then vary ɛ over 7 order of magnitude and determine f(ɛ) as a function of ɛ. We find that the value of α takes on minimum values near discrete resonant energies and that as the normal component of the magnetic field goes to zero, α also goes to zero.

  8. Could bipolarity be influenced by stressful life events? A reflection based on a case report.

    Science.gov (United States)

    Bries, Alice; Reynaert, Christine; Zdanowicz, Nicolas

    2014-11-01

    Bipolar disorder (BPD) has over the last fifteen years been considered as a biological disease with genetic bases, possibly triggered by stress factors. On the basis of a clinical case, we will question this theory. Mrs. X, a patient with a history of domestic violence, has two manic episodes that corresponded with conjugal difficulties. This would lead us to believe that stressful life events may have triggered the onset and the relapse of the illness of our patient. To confirm this, we made a literature review with the keywords bipolar disorder, stress, family functioning and domestic violence on three databases: PubMed, PsycInfo and PsycArticles. Studies show that BPD has likely genetic and biological origins. It is also established in the literature that stressful life events influence the course of the disease, with for example the "Kindling" effect. However, there is very few data regarding the precise nature of these events. It is also established that the family interactions are affected by the BPD. Nonetheless, little is known about the influence of the family's interactions on the onset of the disease. Our clinical case raises the question of the stress factors that may influence the onset and the course of BPD. It also raises the question of the possible link between BPD and domestic violence and the question of theeffect of stressors on the genetic and biological factors, introducing a more psychodynamic view of BPD. Further research on this subject should allow us to expand the treatment to more comprehensive care.

  9. Rejection attitudes, poor parental bonding, and stressful life events in heroin addicts' families.

    Science.gov (United States)

    Pomini, Valeria; Gournellis, Rossetos; Kokkevi, Anna; Tomaras, Vlassis; Papadimitriou, George; Liappas, John

    2014-12-01

    The influence of family factors on the development and/or on maintenance of heroin addiction still remains unclear. The aim of this study was to investigate family factors, which might be associated with heroin addiction in a sample of male individuals. A group of 40 heroin addicts' families was compared with a group of 17 families with a member presenting schizophrenia and a group of 27 families with mentally healthy members in regard to (1) parents' rejection attitudes toward their adult child, (2) quality of parental bond, as perceived by the adult child, and (3) stressful life events in the nuclear family. The main findings showed that the degree of rejection by the fathers in the heroin addicts' families as well as in the subjects with schizophrenia was significantly higher compared to the fathers' degree of rejection in the control group. Moreover, the degree of rejection by mothers in the heroin addicts' families was significantly higher compared to the mothers' degree of rejection in the control group. Heroin addicts reported that they had perceived less care from their fathers than healthy controls. The total number of stressful life events in the nuclear family was higher in the patients with schizophrenia in comparison to the healthy controls. Also, in the heroin addicts' group, a significantly higher number of fathers presented a current or past psychiatric disorder. The findings of this study showed the importance of negative family factors in the course of heroin addiction.

  10. Reading the Bible for guidance, comfort, and strength during stressful life events.

    Science.gov (United States)

    Hamilton, Jill B; Moore, Angelo D; Johnson, Khishaana A; Koenig, Harold G

    2013-01-01

    The use of religious practices to promote mental health among African Americans is well documented. African Americans are more likely to report strong religious affiliations and to use religion over prescribed medications for mental health problems. However, few studies have explored how African Americans use religious practices in response to stressful life events. The aim of this study is to examine how African American women and men find comfort in using scripture passages from The Bible. Fifty-four African American adults residing in the Southeastern United States participated in a qualitative descriptive study using open-ended semistructured interviews. Participants were asked to describe their use of scripture passages from The Bible and the personal meanings associated with these scriptures in the context of a family death or life-threatening illness. These participants used scripture passages categorized as God as Protector, God as Beneficent, Praise and Thanksgiving, God as Healer, Memory of Forefathers, Prayers to God, and Life after Death. Few gender differences were noted. However, women were more likely to use scripture passages of God as Protector and Life after Death, whereas men were more likely to use God as Beneficent and God as Healer. The religious practice of reading scripture passages from The Bible is a mental health-promoting strategy used during stressful life events. The findings of this study have practical uses for nurses and can be used to inform acceptable and sensitive approaches in addressing mental health issues and spiritual care needs in African American patients.

  11. A Kinematic, Flexure-based Mechanism for Precise, Parallel Motion for the Hertz Variable-delay Polarization Modulator (VPM)

    Science.gov (United States)

    Voellmer, G. M.; Chuss, D. T.; Jackson, M.; Krejny, M.; Moseley, S. H.; Novak, G.; Wollack, E. J.

    2008-01-01

    We describe the design of the linear motion stage for a Variable-delay Polarization Modulator (VPM) and of a grid flattener that has been built and integrated into the Hertz ground-based, submillimeter polarimeter. VPMs allow the modulation of a polarized source by controlling the phase difference between two linear, orthogonal polarizations. The size of the gap between a mirror and a very flat polarizing grid determines the amount of the phase difference. This gap must be parallel to better than 1% of the wavelength. A novel, kinematic, flexure-based mechanism is described that passively maintains the parallelism of the mirror and the grid to 1.5 pm over a 150 mm diameter, with a 400 pm throw. A single piezoceramic actuator is used to modulate the gap, and a capacitive sensor provides position feedback for closed-loop control. A simple device that ensures the planarity of the polarizing grid is also described. Engineering results from the deployment of this device in the Hertz instrument April 2006 at the Submillimeter Telescope Observatory (SMTO) in Arizona are presented.

  12. Prevalence of internet addiction and its association with stressful life events and psychological symptoms among adolescent internet users.

    Science.gov (United States)

    Tang, Jie; Yu, Yizhen; Du, Yukai; Ma, Ying; Zhang, Dongying; Wang, Jiaji

    2014-03-01

    Internet addiction (IA) among adolescents is a serious public health problem around the world. However, there have been few studies that examine the association between IA and stressful life events and psychological symptoms among Chinese adolescent internet users. We examined the association between IA and stressful life events and psychological symptoms among a random sample of school students who were internet users (N=755) in Wuhan, China. Internet addiction, stressful life events, coping style and psychological symptoms were measured by self-rated scales. The prevalence rate of internet addiction was 6.0% among adolescent internet users. Logistic regression analyses indicated that stressors from interpersonal problem and school related problem and anxiety symptoms were significantly associated with IA after controlling for demographic characteristics. Analyses examining the coping style with the IA revealed that negative coping style may mediate the effects of stressful life events to increase the risk of IA. However, no significant interaction of stressful life events and psychological symptoms was found. These findings of the current study indicate a high prevalence of internet addiction among Chinese adolescent internet users and highlight the importance of stressors from interpersonal problem and school related problem as a risk factor for IA which mainly mediated through negative coping style. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Equifinality and the Scaling Exponent of the Structure Function

    Science.gov (United States)

    Fitton, G. F.; Mezematy, Y.; Schertzer, D. J. M.; Tchiguirinskaia, I.

    2014-12-01

    In turbulence the structure function is by far the most widely used tool for the empirical analysis of the velocity field. This is due mainly to the work of Kolmogorov (1941) who hypothesised a homogeneous flux of energy and derived the famous 2/3 power law for the second-order structure function; — which corresponds to a 5/3 law for the energy spectrum (Obukhov, 1942). In 1962 Kolmogorov refined his hypothesis to take into account the intermittency of the flux, with the consequence that the exponent ξ(q) of the structure function is not longer proportional to its statistical order q. In this communication, we first show that the refined hypothesis can lead to different models that can have opposite intermittency corrections. Secondly, we demonstrate that the inverse problem, i.e., starting from a given expression of ξ(q) to recover the involved flux leads to an interesting problem of equifinality for the definition of this flux. This is done in particular in the framework of the Fractionally Integrated Flux model that gives a precise meaning to the refined hypothesis. The theoretical and practical consequences are illustrated with the help data analysis and simulations of turbulence in wind farms and urban lakes.

  14. Critical exponent for a damped wave system with fractional integral

    Directory of Open Access Journals (Sweden)

    Mijing Wu

    2015-08-01

    Full Text Available We shall present the critical exponent $$ F(p, q,\\alpha:=\\max\\big\\{\\alpha+\\frac{(\\alpha+1(p+1}{pq-1}, \\alpha+\\frac{(\\alpha+1(q+1}{pq-1}\\big\\}-\\frac{1}{2} $$ for the Cauchy problem $$\\displaylines{ u_{tt}-u_{xx}+u_t=J_{0|t}^{\\alpha}(|v|^{p}, \\quad (t,x\\in\\mathbb{R}^{+}\\times\\mathbb{R},\\cr v_{tt}-v_{xx}+v_t=J_{0|t}^{\\alpha}(|u|^{q}, \\quad (t, x\\in\\mathbb{R}^{+}\\times\\mathbb{R},\\cr (u(0,x, u_t(0,x=(u_0(x,u_1(x, \\quad x\\in \\mathbb{R},\\cr (v(0,x, v_t(0,x=(v_0(x,v_1(x, \\quad x\\in \\mathbb{R},\\cr }$$ where $p,q\\geq 1$, $pq>1$ and $0<\\alpha<1/2$; that is, the small data global existence of solutions can be derived to the problem above if $F(p, q, \\alpha<0$. Furthermore, in the case of $F(p, q, \\alpha\\geq 0$ the non-existence of global solution can be obtained with the initial data having positive average value.

  15. A generalization of the power law distribution with nonlinear exponent

    Science.gov (United States)

    Prieto, Faustino; Sarabia, José María

    2017-01-01

    The power law distribution is usually used to fit data in the upper tail of the distribution. However, commonly it is not valid to model data in all the range. In this paper, we present a new family of distributions, the so-called Generalized Power Law (GPL), which can be useful for modeling data in all the range and possess power law tails. To do that, we model the exponent of the power law using a non-linear function which depends on data and two parameters. Then, we provide some basic properties and some specific models of that new family of distributions. After that, we study a relevant model of the family, with special emphasis on the quantile and hazard functions, and the corresponding estimation and testing methods. Finally, as an empirical evidence, we study how the debt is distributed across municipalities in Spain. We check that power law model is only valid in the upper tail; we show analytically and graphically the competence of the new model with municipal debt data in the whole range; and we compare the new distribution with other well-known distributions including the Lognormal, the Generalized Pareto, the Fisk, the Burr type XII and the Dagum models.

  16. Regularized semiclassical limits: Linear flows with infinite Lyapunov exponents

    KAUST Repository

    Athanassoulis, Agissilaos

    2016-08-30

    Semiclassical asymptotics for Schrödinger equations with non-smooth potentials give rise to ill-posed formal semiclassical limits. These problems have attracted a lot of attention in the last few years, as a proxy for the treatment of eigenvalue crossings, i.e. general systems. It has recently been shown that the semiclassical limit for conical singularities is in fact well-posed, as long as the Wigner measure (WM) stays away from singular saddle points. In this work we develop a family of refined semiclassical estimates, and use them to derive regularized transport equations for saddle points with infinite Lyapunov exponents, extending the aforementioned recent results. In the process we answer a related question posed by P.L. Lions and T. Paul in 1993. If we consider more singular potentials, our rigorous estimates break down. To investigate whether conical saddle points, such as -|x|, admit a regularized transport asymptotic approximation, we employ a numerical solver based on posteriori error control. Thus rigorous upper bounds for the asymptotic error in concrete problems are generated. In particular, specific phenomena which render invalid any regularized transport for -|x| are identified and quantified. In that sense our rigorous results are sharp. Finally, we use our findings to formulate a precise conjecture for the condition under which conical saddle points admit a regularized transport solution for the WM. © 2016 International Press.

  17. Scaling exponents in space plasmas: a fractional Levy model

    Science.gov (United States)

    Watkins, N. W.; Credgington, D.; Hnat, B.; Chapman, S. C.; Freeman, M. P.; Greenhough, J.

    Mandelbrot introduced the concept of fractals to describe the non-Euclidean shape of many aspects of the natural world In the time series context he proposed the use of fractional Brownian motion fBm to model non-negligible temporal persistence the Joseph Effect and Levy flights to quantify large discontinuities the Noah Effect In space physics the effects are manifested as intermittency and long-range correlation well-established features of geomagnetic indices and their solar wind drivers In order to capture and quantify the Noah and Joseph effects in one compact model we propose the application of a bridge -fractional Levy motion fLm -to space physics We perform an initial evaluation of some previous scaling results in this paradigm and show how fLm can model the previously observed exponents physics 0509058 in press Space Science Reviews We discuss the similarities and differences between fLm and ambivalent processes based on fractional kinetic equations e g Brockmann et al Nature 2006 and suggest some new directions for the future

  18. The unitary cover of a finite group and the exponent of the Schur multiplier

    OpenAIRE

    Sambonet, Nicola

    2013-01-01

    For a finite group we introduce a particular central extension, the unitary cover, having minimal exponent among those satisfying the projective lifting property. We obtain new bounds for the exponent of the Schur multiplier relating to subnormal series, and we discover new families for which the bound is the exponent of the group. Finally, we show that unitary covers are controlled by the Zel'manov solution of the restricted Burnside problem for 2-generator groups.

  19. Partial differential equations with variable exponents variational methods and qualitative analysis

    CERN Document Server

    Radulescu, Vicentiu D

    2015-01-01

    Partial Differential Equations with Variable Exponents: Variational Methods and Qualitative Analysis provides researchers and graduate students with a thorough introduction to the theory of nonlinear partial differential equations (PDEs) with a variable exponent, particularly those of elliptic type. The book presents the most important variational methods for elliptic PDEs described by nonhomogeneous differential operators and containing one or more power-type nonlinearities with a variable exponent. The authors give a systematic treatment of the basic mathematical theory and constructive meth

  20. ADHD symptoms in healthy adults are associated with stressful life events and negative memory bias.

    Science.gov (United States)

    Vrijsen, Janna N; Tendolkar, Indira; Onnink, Marten; Hoogman, Martine; Schene, Aart H; Fernández, Guillén; van Oostrom, Iris; Franke, Barbara

    2017-10-28

    Stressful life events, especially Childhood Trauma, predict ADHD symptoms. Childhood Trauma and negatively biased memory are risk factors for affective disorders. The association of life events and bias with ADHD symptoms may inform about the etiology of ADHD. Memory bias was tested using a computer task in N = 675 healthy adults. Life events and ADHD symptoms were assessed using questionnaires. The mediation of the association between life events and ADHD symptoms by memory bias was examined. We explored the roles of different types of life events and of ADHD symptom clusters. Life events and memory bias were associated with overall ADHD symptoms as well as inattention and hyperactivity/impulsivity symptom clusters. Memory bias mediated the association of Lifetime Life Events, specifically Childhood Trauma, with ADHD symptoms. Negatively biased memory may be a cognitive marker of the effects of Childhood Trauma on the development and/or persistence of ADHD symptoms.

  1. Cancer as a stressful life event: Perceptions of children with cancer and their peers.

    Science.gov (United States)

    Sharp, Katianne M Howard; Lindwall, Jennifer J; Willard, Victoria W; Long, Alanna M; Martin-Elbahesh, Karen M; Phipps, Sean

    2017-09-01

    The medical traumatic stress model is commonly applied to childhood cancer, assuming that the diagnosis of cancer is a traumatic event. However, to the authors' knowledge, little is known regarding what specifically children perceive as stressful about cancer or how it compares with other stressful events more often experienced by children. Children with cancer (254 children) and demographically similar peers without a history of serious illness (202 children) identified their most stressful life event as part of a diagnostic interview assessing for symptoms of posttraumatic stress disorder (PTSD). The events identified as most stressful were categorized thematically, with categories established separately for cancer-related and non-cancer-related events. Events also were examined to assess whether they met Diagnostic and Statistical Manual of Mental Disorders (DSM) A criteria for PTSD. In the group of children with cancer, 54% described a cancer-related event as the most stressful event they had experienced. Six distinct categories of cancer-related events and 10 categories of non-cancer-related events were identified. The same noncancer events were identified by children in both groups, and occurred at similar frequencies. The percentage of cancer-related events that met DSM A criteria for PTSD differed dramatically depending on which version of the DSM was applied. Children do not necessarily view their cancer experience as their most stressful life event. The findings of the current study suggest that the diagnosis of cancer might be better viewed as a manageable stressor rather than a major trauma, and are consistent with the change in the fifth edition of the DSM to eliminate the diagnosis of a life-threatening illness as a qualifying trauma for PTSD. Cancer 2017;123:3385-93. © 2017 American Cancer Society. © 2017 American Cancer Society.

  2. Psychological impact of chronic hepatitis C: comparison with other stressful life events and chronic diseases.

    Science.gov (United States)

    Castera, Laurent; Constant, Aymery; Bernard, Pierre-Henri; de Ledinghen, Victor; Couzigou, Patrice

    2006-03-14

    To examine the psychological impact of chronic hepatitis C (CHC) diagnosis in a large cohort of CHC patients as compared with other stressful life events and chronic diseases carrying a risk of life-threatening complications. One hundred and eighty-five outpatients with compensated CHC were asked to self-grade, using a 100-mm visual analogue scale (VAS), the degree of stress caused by the learning of CHC diagnosis and the perceived severity of their disease. Diagnosis-related stress was compared to four other stressful life events and perceived CHC severity was compared to four other common chronic diseases. Learning of CHC diagnosis was considered a major stressful event (mean+/-SD scores: 72+/-25), significantly less than death of a loved-one (89+/-13, Pdivorce (78+/-23, P<0.007), but more than job dismissal (68+/-30, P<0.04) and home removal (26+/-24, P<0.0001). CHC was considered a severe disease (74+/-19), after AIDS (94+/-08, P<0.001) and cancer (91+/-11, P<0.001), but before diabetes (66+/-23, P<0.001) and hypertension (62+/-20, P<0.001). Perceived CHC severity was not related to the actual severity of liver disease, assessed according to Metavir fibrosis score. In multivariate analysis, diagnosis-related stress was related to perceived disease severity (P<0.001), trait anxiety (P<0.001) and infection through blood transfusion (P<0.001). Our results show the considerable psychological and emotional burden that a diagnosis of CHC represents, even in the absence of significant liver disease. They should be taken into account when announcing a diagnosis of CHC in order to reduce its negative effects.

  3. Stressful life events, hopelessness, and coping strategies among impulsive suicide attempters

    Directory of Open Access Journals (Sweden)

    Shivanand Kattimani

    2015-01-01

    Full Text Available Background: Suicides are among the most important causes of death in the economically productive population. Characteristics of impulsive and nonimpulsive suicide attempters may differ which would have a bearing on planning preventive measures. Aims: This study aimed to characterize the clinical and psychological profile of impulsive and nonimpulsive suicide attempters. Settings and Design: This retrospective comprehensive chart-based study was conducted at a tertiary care hospital in South India. Methods: The study utilized records of patients over a period of 3 years. An attempt was considered impulsive if the time between suicidal idea and the attempt was <30 min. Stressful life events were assessed using presumptive stressful life events scale; hopelessness was evaluated using Beck Hopelessness Scale (BHS and coping was measured using Coping Strategies Inventory Short Form. Statistical Analysis Used: Impulsive and nonimpulsive suicide attempters were compared using appropriate inferential statistical tests. Results: Of 316 patients, 151 were classified as having an impulsive suicidal attempt (47.8% of the sample. The impulsive and nonimpulsive suicide attempters did not differ on demographic characteristics. Use of natural plant products was more common in impulsive attempters (27.2% vs. 12.7%, while physical methods like hanging was less common (0.7% vs. 7.3%. Those with an impulsive attempt were more likely to have a recent contact with a health professional (24.5% vs. 4.5%. Impulsive suicide attempters had higher scores on BHS (Mann-Whitney U = 7680.5, P < 0.001, and had recollected greater number of stressors. Conclusion: Impulsive suicide attempters differ from nonimpulsive suicide attempters in clinical features like methods of attempt, presence of hopelessness, and stressors.

  4. Gender differences in the rates of exposure to stressful life events and sensitivity to their depressogenic effects.

    Science.gov (United States)

    Kendler, K S; Thornton, L M; Prescott, C A

    2001-04-01

    Women are at greater risk for major depression than men. The authors sought to determine whether the gender difference in prevalence for major depression was due to more frequent exposure to stressful life events and/or greater sensitivity to their depressogenic effects. Male-male, female-female, and male-female twin pairs from a population-based registry were personally interviewed. Each interview assessed the occurrence, to the nearest month, of 18 personal and social network classes of stressful life events and episode onsets of major depression. Standard logistic regression analyses were conducted for the same-sex pairs, and each female twin in the opposite-sex pairs was compared with her male co-twin by using conditional logistic regression. Women consistently reported higher rates of housing problems, loss of confidant, crises and problems getting along with individuals in their proximal network, and illness of individuals within their distal network. In both the same-sex and opposite-sex samples, men reported higher rates of job loss, legal problems, robbery, and work problems. Consistent sex differences in the depressogenic effect of stressful life events were seen for three event categories: men were more sensitive to the depressogenic effects of divorce or separation and work problems; women were more sensitive to the depressogenic effects of problems getting along with individuals in their proximal network. None of the gender difference in prevalence of major depression could be explained by differing rates of or sensitivities to stressful life events. Women reported more interpersonal whereas men reported more legal and work-related stressful life events. Most life event categories influenced the risk for major depression similarly in the two sexes. The results suggest that the greater prevalence of major depression in women versus men is due neither to differences in the rates of reported stressful life events nor to differential sensitivity to their

  5. The association between stressful life events and depressive symptoms among Cypriot university students: a cross-sectional descriptive correlational study

    Science.gov (United States)

    2013-01-01

    Background Previous findings suggest that stressful life events have a causal relationship with depressive symptoms. However, to date little is known concerning the contribution of the number and severity of recent stressful life events on the prevalence of depressive symptoms among university students. The aim of this study was to investigate the prevalence of depressive symptoms and its association with the number and the severity of self-reported stressful life events among university students in Cyprus. Methods A descriptive correlational design with cross sectional comparison was used. The CES-D scale was applied for the assessment of depressive symptoms and the LESS instrument for stressful life events. Both scales were completed anonymously and voluntarily by 1.500 students (response rate 85%). Results The prevalence of mild to moderate depressive symptoms [CES-D score between 16 and 21] and of clinically significant depressive symptoms [CES-D score ≥ 22] were 18.8% and 25.3% respectively. There were statistically significant differences in clinically significant depressive symptoms by gender, with higher rates among women (x2 = 8.53, df = 1, p = 0.003). Higher scores on the LESS scale were associated with more frequent reports of clinical depressive symptoms (x2 = 70.63, df = 4, p stressful life events during the previous year (OR = 2.64 95% CI: 1.02, 6.83) and a severe degree of stress due to these events (total LESS score > 351, OR = 3.03 95% CI: 1.66, 5.39) were more likely to manifest clinical depressive symptoms. Conclusions The high frequency of occurrence of depressive symptoms among Cypriot university students, as well as the strong association with stressful life events, highlights the need for psychological empowerment strategies towards students by institutional counseling services. PMID:24304515

  6. Development and validation of a Thai stressful life events rating scale for patients with a diagnosis of schizophrenic methamphetamine abuse

    Directory of Open Access Journals (Sweden)

    Ek-uma Imkome

    2017-04-01

    Full Text Available This study aimed to psychometrically test a Thai Stressful Life Events Rating Scale (TSLERS. Factor analysis was done on data collected from 313 patients with schizophrenia and methamphetamine abuse in Thailand from April to May, 2015. Results identified the following problems impacting physical and mental health: social relationship and social concerns, money, family life, life security, and career. Evaluation of the psychometric scale properties demonstrated acceptable validity and reliability. TSLERS provided scientific and empirical data about stressful life events of patients with schizophrenia and methamphetamine abuse, and was suitable for stress detection and suggesting further innovations.

  7. Highly deformed grain: from the Hertz contact limitation to a new strain field description in 2D

    Science.gov (United States)

    Mora, Serge; Vu, Thi-Lo; Barés, Jonathan; Nezamabadi, Saeid

    2017-06-01

    Most of the 2D studies on granular materials consider an assembly of cylindrical particles in the small deformation regime. Investigating the range of validity of the small deformation hypothesis is therefore of crucial importance in order to determine the quantitative relevance of the predictions emerging from these 2D studies. We introduce here a novel experimental set-up based on high resolution imaging and image correlation, and capable of measuring the strain field inside the particles with a cutting edge accuracy. We measure the strain field inside a unique circular cylindrical elastic particle undergoing an uniaxial compression. The significant deviations arising from the comparison with the predictions of the small deformation limit predicted by the Hertz's theory, and numerical simulations, give insight to improve the modeling of 2D granular materials.

  8. Celebrando São Besso ou o que Robert Hertz e a Escola Francesa de Sociologia têm a nos dizer sobre festas, rituais e simbolismo

    Directory of Open Access Journals (Sweden)

    Renata de Castro Menezes

    2009-01-01

    Full Text Available Este artigo apresenta reflexões sobre as possibilidades e as dificuldades do estudo de festas religiosas através da interpretação de um texto de Robert Hertz (um dos pesquisadores da Escola Francesa de Sociologia, originalmente publicado em 1913, que versa sobre a festa de São Besso, um evento religioso que ocorre nos alpes italianos. O objetivo do presente trabalho é destacar as pistas que Hertz deixou abertas em seu estudo e sugerir maneiras de nos apropriarmos de seus insights em nossas análises atuais.This article presents some reflections about the possibilities and difficulties in the study of religious festivals. It does so by reinterpreting a text written by Robert Hertz, one of the researches of the French School of Sociology. It is a text about Saint Besso’s festival, originally published in 1913. The aim of the article is to stress some of the clues that Hertz opened with his work and to suggest how his insights can be useful for our own analyses about festivals.

  9. Error Exponents of Low-Density Parity-Check Codes on the Binary Erasure Channel

    OpenAIRE

    Mora, Thierry; Rivoire, Olivier

    2006-01-01

    We introduce a thermodynamic (large deviation) formalism for computing error exponents in error-correcting codes. Within this framework, we apply the heuristic cavity method from statistical mechanics to derive the average and typical error exponents of low-density parity-check (LDPC) codes on the binary erasure channel (BEC) under maximum-likelihood decoding.

  10. The spatial meaning of Pareto's scaling exponent of city-size distribution

    CERN Document Server

    Chen, Yanguang

    2013-01-01

    The scaling exponent of a hierarchy of cities used to be regarded as a fractal parameter. The Pareto exponent was treated as the fractal dimension of size distribution of cities, while the Zipf exponent was treated as the reciprocal of the fractal dimension. However, this viewpoint is not exact. In this paper, I will present a new interpretation of the scaling exponent of rank-size distributions. The ideas from fractal measure relation and the principle of dimension consistency are employed to explore the essence of Pareto's and Zipf's scaling exponents. The Pareto exponent proved to be a ratio of the fractal dimension of a network of cities to the average dimension of city population. Accordingly, the Zipf exponent is the reciprocal of this dimension ratio. On a digital map, the Pareto exponent can be defined by the scaling relation between a map scale and the corresponding number of cities based on this scale. The cities of the United States of America in 1900, 1940, 1960, and 1980 and Indian cities in 1981...

  11. Variation of Zipf's exponent in one hundred live languages: A study of the Holy Bible translations

    Science.gov (United States)

    Mehri, Ali; Jamaati, Maryam

    2017-08-01

    Zipf's law, as a power-law regularity, confirms long-range correlations between the elements in natural and artificial systems. In this article, this law is evaluated for one hundred live languages. We calculate Zipf's exponent for translations of the holy Bible to several languages, for this purpose. The results show that, the average of Zipf's exponent in studied texts is slightly above unity. All studied languages in some families have Zipf's exponent lower/higher than unity. It seems that geographical distribution impresses the communication between speakers of different languages in a language family, and affect similarity between their Zipf's exponent. The Bible has unique concept regardless of its language, but the discrepancy in grammatical rules and syntactic regularities in applying stop words to make sentences and imply a certain concept, lead to difference in Zipf's exponent for various languages.

  12. Hurst exponent and prediction based on weak-form efficient market hypothesis of stock markets

    Science.gov (United States)

    Eom, Cheoljun; Choi, Sunghoon; Oh, Gabjin; Jung, Woo-Sung

    2008-07-01

    We empirically investigated the relationships between the degree of efficiency and the predictability in financial time-series data. The Hurst exponent was used as the measurement of the degree of efficiency, and the hit rate calculated from the nearest-neighbor prediction method was used for the prediction of the directions of future price changes. We used 60 market indexes of various countries. We empirically discovered that the relationship between the degree of efficiency (the Hurst exponent) and the predictability (the hit rate) is strongly positive. That is, a market index with a higher Hurst exponent tends to have a higher hit rate. These results suggested that the Hurst exponent is useful for predicting future price changes. Furthermore, we also discovered that the Hurst exponent and the hit rate are useful as standards that can distinguish emerging capital markets from mature capital markets.

  13. The relationships between stressful life events during childhood and differentiation of self and intergenerational triangulation in adulthood.

    Science.gov (United States)

    Peleg, Ora

    2014-12-01

    This study examined the relationships between stressful life events in childhood and differentiation of self and intergenerational triangulation in adulthood. The sample included 217 students (173 females and 44 males) from a college in northern Israel. Participants completed the Hebrew versions of Life Events Checklist (LEC), Differentiation of Self Inventory-Revised (DSI-R) and intergenerational triangulation (INTRI). The main findings were that levels of stressful life events during childhood and adolescence among both genders were positively correlated with the levels of fusion with others and intergenerational triangulation. The levels of positive life events were negatively related to levels of emotional reactivity, emotional cut-off and intergenerational triangulation. Levels of stressful life events in females were positively correlated with emotional reactivity. Intergenerational triangulation was correlated with emotional reactivity, emotional cut-off, fusion with others and I-position. Findings suggest that families that experience higher levels of stressful life events may be at risk for higher levels of intergenerational triangulation and lower levels of differentiation of self. © 2014 International Union of Psychological Science.

  14. The Moderating Effect of Impulsivity on the Relationship between Stressful Life Events and Depression among College Women

    Science.gov (United States)

    Clarke, Dave

    2012-01-01

    Based on the transpersonal model of stress, the purpose of the study was to investigate the moderating effect of impulsivity on the relationship between stressful life events (SLE) and depression among first year university women. Impulsivity consists of tendencies towards lack of premeditation, lack of perseverance, urgency and sensation seeking.…

  15. Stressful life events, hopelessness, and suicidal intent in patients admitted with attempted suicide in a tertiary care general hospital.

    Science.gov (United States)

    Jaiswal, S V; Faye, A D; Gore, S P; Shah, H R; Kamath, R M

    2016-01-01

    Suicide is a psychiatric emergency. Stressors in life and social variables (like marital status, family, and social support) are among the determinants of suicide. Hopelessness and suicidal intent are among the psychological variables that have shown promise in the prediction of suicide. To assess stressful life events, hopelessness, suicidal intent, and sociodemographic variables in patients of attempted suicide. Fifty consecutive patients admitted with attempted suicide were interviewed. Presumptive Stressful Life Event Scale, Beck Hopelessness Scale, and Beck Suicidal Intent Scale were used along with a semistructured pro forma for interview. Data were analyzed with statistical tests. Sixty-six percent of the participants were females, 72% were less than 30 years of age. Sixty-six percent of the patients had stressful life event score between 101 and 200 with the mean score of 127. The stressful life event score in those who considered they are in need of psychiatric help was significantly high. Most of the patients had mild (34%) and moderate (40%) degrees of hopelessness, and the mean score was 9.64. The mean suicidal intent in the participants was 25.14, when correlated with hopelessness score significant positive correlation was found. Lethality of the attempt increases with the increase in hopelessness.

  16. Stressful life events, hopelessness, and suicidal intent in patients admitted with attempted suicide in a tertiary care general hospital

    Directory of Open Access Journals (Sweden)

    S V Jaiswal

    2016-01-01

    Full Text Available Background: Suicide is a psychiatric emergency. Stressors in life and social variables (like marital status, family, and social support are among the determinants of suicide. Hopelessness and suicidal intent are among the psychological variables that have shown promise in the prediction of suicide. Aims and Objectives: To assess stressful life events, hopelessness, suicidal intent, and sociodemographic variables in patients of attempted suicide. Materials and Methods: Fifty consecutive patients admitted with attempted suicide were interviewed. Presumptive Stressful Life Event Scale, Beck Hopelessness Scale, and Beck Suicidal Intent Scale were used along with a semistructured pro forma for interview. Data were analyzed with statistical tests. Results: Sixty-six percent of the participants were females, 72% were less than 30 years of age. Sixty-six percent of the patients had stressful life event score between 101 and 200 with the mean score of 127. The stressful life event score in those who considered they are in need of psychiatric help was significantly high. Most of the patients had mild (34% and moderate (40% degrees of hopelessness, and the mean score was 9.64. The mean suicidal intent in the participants was 25.14, when correlated with hopelessness score significant positive correlation was found. Conclusion: Lethality of the attempt increases with the increase in hopelessness.

  17. Validation of the revised stressful life event questionnaire using a hybrid model of genetic algorithm and artificial neural networks.

    Science.gov (United States)

    Sali, Rasoul; Roohafza, Hamidreza; Sadeghi, Masoumeh; Andalib, Elham; Shavandi, Hassan; Sarrafzadegan, Nizal

    2013-01-01

    Stressors have a serious role in precipitating mental and somatic disorders and are an interesting subject for many clinical and community-based studies. Hence, the proper and accurate measurement of them is very important. We revised the stressful life event (SLE) questionnaire by adding weights to the events in order to measure and determine a cut point. A total of 4569 adults aged between 18 and 85 years completed the SLE questionnaire and the general health questionnaire-12 (GHQ-12). A hybrid model of genetic algorithm (GA) and artificial neural networks (ANNs) was applied to extract the relation between the stressful life events (evaluated by a 6-point Likert scale) and the GHQ score as a response variable. In this model, GA is used in order to set some parameter of ANN for achieving more accurate results. For each stressful life event, the number is defined as weight. Among all stressful life events, death of parents, spouse, or siblings is the most important and impactful stressor in the studied population. Sensitivity of 83% and specificity of 81% were obtained for the cut point 100. The SLE-revised (SLE-R) questionnaire despite simplicity is a high-performance screening tool for investigating the stress level of life events and its management in both community and primary care settings. The SLE-R questionnaire is user-friendly and easy to be self-administered. This questionnaire allows the individuals to be aware of their own health status.

  18. Gene-Environment Interaction Effects of Peer Deviance, Parental Knowledge and Stressful Life Events on Adolescent Alcohol Use.

    Science.gov (United States)

    Cooke, Megan E; Meyers, Jacquelyn L; Latvala, Antti; Korhonen, Tellervo; Rose, Richard J; Kaprio, Jaakko; Salvatore, Jessica E; Dick, Danielle M

    2015-10-01

    The purpose of this study was to address two methodological issues that have called into question whether previously reported gene-environment interaction (GxE) effects for adolescent alcohol use are 'real'. These issues are (1) the potential correlation between the environmental moderator and the outcome across twins and (2) non-linear transformations of the behavioral outcome. Three environments that have been previously studied (peer deviance, parental knowledge, and potentially stressful life events) were examined here. For each moderator (peer deviance, parental knowledge, and potentially stressful life events), a series of models was fit to both a raw and transformed measure of monthly adolescent alcohol use in a sample that included 825 dizygotic (DZ) and 803 monozygotic (MZ) twin pairs. The results showed that the moderating effect of peer deviance was robust to transformation, and that although the significance of moderating effects of parental knowledge and potentially stressful life events were dependent on the scale of the adolescent alcohol use outcome, the overall results were consistent across transformation. In addition, the findings did not vary across statistical models. The consistency of the peer deviance results and the shift of the parental knowledge and potentially stressful life events results between trending and significant, shed some light on why previous findings for certain moderators have been inconsistent and emphasize the importance of considering both methodological issues and previous findings when conducting and interpreting GxE analyses.

  19. The interplay of stressful life events and coping skills on risk for suicidal behavior among youth students in contemporary China: a large scale cross-sectional study

    OpenAIRE

    Tang,Fang; Xue, Fuzhong; Qin, Ping

    2015-01-01

    Background Stressful life events are common among youth students and may induce psychological problems and even suicidal behaviors in those with poor coping skills. This study aims to assess the influence of stressful life events and coping skills on risk for suicidal behavior and to elucidate the underlying mechanism using a large sample of university students in China. Methods 5972 students, randoml...

  20. Perceived stress, life events & coping among higher secondary students of Hyderabad, India: a pilot study.

    Science.gov (United States)

    Augustine, Little Flower; Vazir, Shahnaz; Rao, Sylvia Fernandez; Rao, M Vishnu Vardhana; Laxmaiah, A; Nair, K Madhavan

    2011-07-01

    Psychosocial stressors leading to allostatic load need to be explored further as these have great scope for early intervention. Stress studies done in India are mostly based on sources of stress and objective measures of stress. Therefore, the objective of the present study was to assess stress appraisal among students (16-17 yr) and to identify institution-specific differences (Private vs. Government) in stress appraisal and coping. The study was carried out among 16-17 yr old apparently normal students. Eighty students were recruited from six schools ensuring equal representation from gender/category of schools (Government/Private). Validated and culturally adaptable behavioural scales for perceived stress (PSS), stressful life events (LES) and coping were administered. Psychological morbidity was assessed using GHQ-12. Data on 75 students were available for statistical analysis. The students of both Government and Private schools showed similar stress perception, though the former tend to have a higher mean score. The scores were significantly higher on avoidance coping (Pcoping as the independent predictor of perceived stress (R2 = 10%). Students from Government schools had significantly higher scores on avoidance coping and therefore, suitable for a systematic study on chronic stress for early intervention.

  1. Stressful life-events in childhood and risk of multiple sclerosis: a Danish nationwide cohort study.

    Science.gov (United States)

    Nielsen, Nete Munk; Pedersen, Bo V; Stenager, Egon; Koch-Henriksen, Nils; Frisch, Morten

    2014-10-01

    Current knowledge concerning the association between exposure to stressful life-events (SFLEs) in childhood and later risk of multiple sclerosis (MS) is sparse. We studied the associations between SFLEs in childhood and subsequent risk of MS in a nationwide cohort of 2.9 million Danes born from 1968 to 2011. A SFLE in childhood was defined as exposure before age 18 years to parental divorce, parental death, or death of a sibling, using information from the Danish Civil Registration System. MS cases in the cohort were identified in the Danish Multiple Sclerosis Registry. Associations of SFLE with MS risk were evaluated by incidence rate ratios (RR) of MS obtained in log-linear Poisson regression models. Persons exposed to any SFLE in childhood were at 11% elevated risk of MS (RR = 1.11; 95% confidence interval: 1.03-1.20), compared to non-exposed persons. Stratification by subtype of SFLE showed that parental death and death of a sibling were not associated with MS risk. However, persons exposed to parental divorce were at 13% increased risk of developing MS compared to non-exposed (RR = 1.13; 1.04-1.23). Associations of SFLEs in childhood with risk of MS are weak. However, parental divorce is somehow associated with modestly increased risk of MS. © The Author(s), 2014.

  2. Stressful life events, worry, and rumination predict depressive and anxiety symptoms in young adolescents.

    Science.gov (United States)

    Young, Cara C; Dietrich, Mary S

    2015-02-01

    Depression and anxiety are highly prevalent and frequently comorbid mental health disorders that often manifest during childhood and adolescence. The purpose of this study was to prospectively examine potential common underlying mechanisms predicting the development of depressive and anxiety symptoms to identify mutual underlying modifiable risk factors to target with mental health promotion and prevention interventions. A community-based sample of 11- to 15-year-old adolescents participated in a prospective, longitudinal pilot study with three waves of data collection over a 6-month period. At baseline, stressful life events, worry, and rumination accounted for 35% of the variance in anxiety scores (adjusted R(2) = 0.28) and 58% of the variance in depressive symptoms (adjusted R(2) = 0.53), while at Time 3 (T3; 6 months post baseline) these variables accounted for 63% of the variance in anxiety scores (adjusted R(2) = 0.59) and 45% of the variance in depressive symptoms (adjusted R(2) = 0.39). After controlling for baseline values, increases in stress, worry, and rumination were predictive of both depressive and anxiety symptoms at T3. Study findings point to the importance of prevention and early intervention programs including content addressing stress management, rumination, and worry. © 2015 Wiley Periodicals, Inc.

  3. Inner-City African-American Women's Adolescence as Stressful Life Events: Understanding Substance Abusing Behavior.

    Science.gov (United States)

    Durr, Marlese; Small, La Fleur F; Dunlap, Eloise

    2010-06-01

    Lula Beatty (2003:59) asks, "What makes a black woman, voluntarily take a substance into her body which alters her perceptions and feelings of well-being?" This research examines African American women's substance abuse as a response to stressful life events grounded in adolescence, drawing in part on the cognitive-transactional approach and distal stressor model to discuss the effects of stressors on mental health and substance abusing behavior. Most respondents viewed their adolescent experiences and the associated stress as tribulations or lessons to be lived through, rather than a signal of needed change in their social, cultural, and ecological life circumstances. The effect of exposure to constant stressors early in the life course coupled with proximal stressors often resulted in negative active responses to stress (i.e. substance abuse) and continued stunted emotional growth. Thus, our findings indicate that the experience of African American women as adolescents contributes to understanding substance abuse amongst this population. These findings further help develop the cognitive-transactional model, while adding to the distal stressors and life process model as a way of considering gender, race, and structural forces.

  4. Dopamine receptor DRD4 gene and stressful life events in persistent attention deficit hyperactivity disorder.

    Science.gov (United States)

    Sánchez-Mora, Cristina; Richarte, Vanesa; Garcia-Martínez, Iris; Pagerols, Mireia; Corrales, Montse; Bosch, Rosa; Vidal, Raquel; Viladevall, Laia; Casas, Miguel; Cormand, Bru; Ramos-Quiroga, Josep Antoni; Ribasés, Marta

    2015-09-01

    We performed a case-control association study in persistent ADHD considering eight candidate genes (DRD4, DAT1/SLC6A3, COMT, ADRA2A, CES1, CYP2D6, LPHN3, and OPRM1) and found additional evidence for the involvement of the Dup 120bp and VNTR 48bp functional variants within the dopamine receptor DRD4 gene in the etiology of adult ADHD. We subsequently investigated the interaction of stressful life events with these two DRD4 polymorphisms, and the impact of such events on the severity of ADHD symptomatology. The gene-by-environment analysis revealed an independent effect of stressful experiences on the severity of persistent ADHD, and a gene-by-environment interaction on the inattentive dimension of the disorder, where non carriers of the Dup 120bp (L) - VNTR 48bp (7R) haplotype were more sensitive to environmental adversity than carriers. These results are in agreement with previous works reporting a relationship between DRD4 and the effect of adverse experiences, which may explain the discordant findings in previous genetic studies and strengthen the importance of gene-by-environment interactions on the severity of ADHD. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  5. Validating the operational bias and hypothesis of universal exponent in landslide frequency-area distribution.

    Directory of Open Access Journals (Sweden)

    Jr-Chuan Huang

    Full Text Available The exponent decay in landslide frequency-area distribution is widely used for assessing the consequences of landslides and with some studies arguing that the slope of the exponent decay is universal and independent of mechanisms and environmental settings. However, the documented exponent slopes are diverse and hence data processing is hypothesized for this inconsistency. An elaborated statistical experiment and two actual landslide inventories were used here to demonstrate the influences of the data processing on the determination of the exponent. Seven categories with different landslide numbers were generated from the predefined inverse-gamma distribution and then analyzed by three data processing procedures (logarithmic binning, LB, normalized logarithmic binning, NLB and cumulative distribution function, CDF. Five different bin widths were also considered while applying LB and NLB. Following that, the maximum likelihood estimation was used to estimate the exponent slopes. The results showed that the exponents estimated by CDF were unbiased while LB and NLB performed poorly. Two binning-based methods led to considerable biases that increased with the increase of landslide number and bin width. The standard deviations of the estimated exponents were dependent not just on the landslide number but also on binning method and bin width. Both extremely few and plentiful landslide numbers reduced the confidence of the estimated exponents, which could be attributed to limited landslide numbers and considerable operational bias, respectively. The diverse documented exponents in literature should therefore be adjusted accordingly. Our study strongly suggests that the considerable bias due to data processing and the data quality should be constrained in order to advance the understanding of landslide processes.

  6. Extreme event distribution in Space Weather: Characterization of heavy tail distribution using Hurst exponents

    Science.gov (United States)

    Setty, V.; Sharma, A.

    2013-12-01

    Characterization of extreme conditions of space weather is essential for potential mitigation strategies. The non-equilibrium nature of magnetosphere makes such efforts complicated and new techniques to understand its extreme event distribution are required. The heavy tail distribution in such systems can be a modeled using Stable distribution whose stability parameter is a measure of scaling in the cumulative distribution and is related to the Hurst exponent. This exponent can be readily measured in stationary time series using several techniques and detrended fluctuation analysis (DFA) is widely used in the presence of non-stationarities. However DFA has severe limitations in cases with non-linear and atypical trends. We propose a new technique that utilizes nonlinear dynamical predictions as a measure of trends and estimates the Hurst exponents. Furthermore, such a measure provides us with a new way to characterize predictability, as perfectly detrended data have no long term memory akin to Gaussian noise Ab initio calculation of weekly Hurst exponents using the auroral electrojet index AL over a span of few decades shows that these exponents are time varying and so is its fractal structure. Such time series data with time varying Hurst exponents are modeled well using multifractional Brownian motion and it is shown that DFA estimates a single time averaged value for Hurst exponent in such data. Our results show that using time varying Hurst exponent structure, we can (a) Estimate stability parameter, -a measure of scaling in heavy tails, (b) Define and identify epochs when the magnetosphere switches between regimes with and without extreme events, and, (c) Study the dependence of the Hurst exponents on the solar activity.

  7. Chaos and stiffness exponents for short-range Gaussian Ising spin glasses

    Science.gov (United States)

    Almeida, Sebastião T. O.; Curado, Evaldo M. F.; Nobre, Fernando D.

    2013-06-01

    Two important exponents in spin-glass theory, namely, the chaos (ζ) and stiffness (y) exponents, are studied for Ising spin glasses with nearest-neighbor Gaussian interactions on different approaches to Bravais lattices. We consider hierarchical lattices of the Migdal-Kadanoff type (both diamond and tress families), with varying fractal dimensions, as well as two lattices of the Wheatstone-bridge family, more specifically, those with fractal dimensions D ≈ 2.32 and D ≈ 3.58. Whenever it is possible to compare, our estimates agree with those obtained from extensive numerical simulations on Bravais lattices, suggesting the present results represent good approximations for these exponents.

  8. The Ångström Exponent and Turbidity of Soot Component in the ...

    African Journals Online (AJOL)

    AOD) show a relatively higher value indicating a polluted ... Keywords: Soot, Ångström exponent, Turbidity, Radiative forcing, Aerosols ..... scattering For UV wavelength g typically falls between 0.6 .... total ozone content from the spectral variation.

  9. Social connectedness, stressful life events, and self-injurious thoughts and behaviors among young adults.

    Science.gov (United States)

    Macrynikola, Natalia; Miranda, Regina; Soffer, Ariella

    2017-09-19

    Preventing self-injurious thoughts and behaviors (SITBs) is particularly challenging on commuter campuses, given lower social cohesion and higher levels of stress than among traditional college populations. The present study examined the relationship between stressful life events (SLEs) and risk for different forms of SITBs, along with the potential buffering role of social connectedness, in a diverse sample of young adults from a commuter college. Participants were 1712 (81% female; 61% racial/ethnic minority; 20% sexual minority) undergraduate and graduate students from a public commuter college in New York City. Participants completed an anonymous survey that inquired about lifetime and recent (past 12months) history of suicidal ideation, suicide attempts, and non-suicidal self-injury (NSSI), along with social connectedness and lifetime history of SLEs. Lower levels of social connectedness and exposure to a higher number of SLEs were associated with engaging in SITBs in the past year, particularly both suicide attempts and non-suicidal self-injury. However, social connectedness did not buffer against the impact of SLEs on SITBs. Data are cross-sectional, limiting conclusions about directionality, and females were overrepresented. Identifying ways to increase social connectedness on diverse commuter campuses may help decrease risk of SITBs. However, it may not buffer against the impact of SLEs on risk of SITBs. Future studies should examine contextual variables (e.g., type and timing of social support) that may play a role in protecting against SITBs, particularly for those with a history of adversity. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. The impact of resilience and subsequent stressful life events on MDD and GAD.

    Science.gov (United States)

    Sheerin, Christina M; Lind, Mackenzie J; Brown, Emily A; Gardner, Charles O; Kendler, Kenneth S; Amstadter, Ananda B

    2018-02-01

    There remains a dearth of research examining the "buffering" effect of resilience, wherein resilience at one point in time would be expected to protect an individual against development of psychopathology following future adverse life events. Using longitudinal data from an epidemiological twin sample (N = 7463), this study tested whether resilience would act as a buffer for stressful life events (SLEs) against risk for major depressive disorder (MDD) and generalized anxiety disorder (GAD). Resilience, demographics, and psychopathology were measured at Time 1 and recent SLEs and current MDD and GAD were measured at Time 2. Final models, controlling for demographic covariates and Time 1 diagnosis, examined the impact of Time 1 resilience, recent SLEs, their interaction, and a three-way interaction adding sex on MDD and GAD. The pattern of findings was the same for MDD and GAD, wherein main effects and two-way interactions of resilience and SLEs were significant, such that greater resilience was protective even in the context of high numbers of past-year SLEs. The three-way interaction was not significant, suggesting that the relationship between SLEs and resilience on psychopathology was the same for both men and women. Findings support the conceptualization of resilience as a buffer against the impact of future life stressors on common internalizing psychopathology. Longitudinal designs and trajectory-based studies that include recurring measures of SLEs could inform conceptualizations of resilience in the context of ongoing adversity and aid in developing interventions aimed at fostering healthy adaptation in the face of stressors. © 2017 Wiley Periodicals, Inc.

  11. Stressful life events in childhood and risk of infectious disease hospitalization.

    Science.gov (United States)

    Nielsen, Nete Munk; Hansen, Anne Vinkel; Simonsen, Jacob; Hviid, Anders

    2012-01-01

    Individuals exposed to high levels of stress might have an increased risk of infectious diseases. However, most of the previous studies have been conducted among adults. To examine the effect of childhood stress, we conducted a nationwide cohort study including all Danish children born from 1977 to 2004. Stressful life events (SFLE) included parental death, death of sibling or parental divorce. Outcome was defined as hospitalizations due to less severe (LSID) or severe infectious diseases (SID). Children were followed until the age of 15 years. The association between SFLE and risk of infections was evaluated through rate ratios (RR) comparing infectious disease incidence ratios in children with and without a history of SFLE. Overall, children exposed to SFLE were at 13% increased risk of LSID (RR = 1.13 (1.10-1.15)), but at no increased risk of SID hospitalization (RR = 1.05 (0.97-1.14)). Looking at the specific type of SFLE, parental divorce increased the risk of LSID (RR = 1.11 (1.09-1.14)) and SID hospitalization (1.11 (1.02-1.21)) by 11%, whereas no increased risk of LSID and SID hospitalization was observed following parental death. Finally, a 34% increased risk of LSID hospitalization (RR = 1.34 (1.23-1.45)) was observed following death of sibling, in contrast to no increased risk of SID hospitalization. Childhood exposure to SFLE, especially parental divorce seems to increase the risk of infectious disease hospitalization. Although we cannot determine whether our observations are the result of a biological effect of stress, adoption of unhealthy behaviours or increased likelihood of hospitalization, our findings do have public health relevance as a considerable proportion of the children today will be exposed to SFLE, the majority to parental divorce.

  12. Electromagnetic scattering on fractional Brownian surfaces and estimation of the Hurst exponent

    OpenAIRE

    Guérin, Charles-Antoine; Saillard, Marc

    2001-01-01

    International audience; Fractional Brownian motion is known to be a realistic model for many natural rough surfaces. It is defined by means of a single parameter, the Hurst exponent, which determines the fractal characteristics of the surface. We propose a method to estimate the Hurst exponent of a fractional Brownian profile from the electromagnetic scattering data. The method is developed in the framework of three usual approximations, with different domains of validity: the Kirchhoff appro...

  13. The recipients of Polish, Greek and Cypriot legal norms. Linguistic exponents

    OpenAIRE

    Gortych-Michalak, Karolina

    2014-01-01

    The paper is dedicated to highlighting and indicating linguistic exponents used for needs to express the recipients of legal rules, which are present in Polish, Greek and Cypriot normative acts. The thesis of the investigation is the suspicion of designation or denotation or different relations existing between linguistic exponents referring to the recipients of legal rules and the real recipients of legal rules. Before the empirical investigations are conducted, some characteristics of legal...

  14. Zeta function for the Lyapunov exponent of a product of random matrices

    Energy Technology Data Exchange (ETDEWEB)

    Mainieri, R. (Neils Bohr Institute, Blegdamsvej 17, Copenhagen O, 2100 (Denmark) Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

    1992-03-30

    A cycle expansion for the Lyapunov exponent of a product of random matrices is derived. The formula is nonperturbative and numerically effective, which allows the Lyapunov exponent to be computed to high accuracy. In particular, the free energy and heat capacity are computed for the one-dimensional Ising model with quenched disorder. The formula is derived by using a Bernoulli dynamical system to mimic the randomness.

  15. Application of largest Lyapunov exponent analysis on the studies of dynamics under external forces

    Science.gov (United States)

    Odavić, Jovan; Mali, Petar; Tekić, Jasmina; Pantić, Milan; Pavkov-Hrvojević, Milica

    2017-06-01

    Dynamics of driven dissipative Frenkel-Kontorova model is examined by using largest Lyapunov exponent computational technique. Obtained results show that besides the usual way where behavior of the system in the presence of external forces is studied by analyzing its dynamical response function, the largest Lyapunov exponent analysis can represent a very convenient tool to examine system dynamics. In the dc driven systems, the critical depinning force for particular structure could be estimated by computing the largest Lyapunov exponent. In the dc+ac driven systems, if the substrate potential is the standard sinusoidal one, calculation of the largest Lyapunov exponent offers a more sensitive way to detect the presence of Shapiro steps. When the amplitude of the ac force is varied the behavior of the largest Lyapunov exponent in the pinned regime completely reflects the behavior of Shapiro steps and the critical depinning force, in particular, it represents the mirror image of the amplitude dependence of critical depinning force. This points out an advantage of this technique since by calculating the largest Lyapunov exponent in the pinned regime we can get an insight into the dynamics of the system when driving forces are applied. Additionally, the system is shown to be not chaotic even in the case of incommensurate structures and large amplitudes of external force, which is a consequence of overdampness of the model and the Middleton's no passing rule.

  16. Aggression and related stressful life events among Chinese adolescents living in rural areas: A cross-sectional study.

    Science.gov (United States)

    Huang, Juan; Tang, Jie; Tang, Lina; Chang, Hong Juan; Ma, Yuqiao; Yan, Qiuge; Yu, Yizhen

    2017-03-15

    Aggression is a serious problem for both individuals and society. Despite progress in aggression research, its persistence among adolescents living in rural areas remains to be investigated. We evaluate the prevalence of aggression and the association between stressful life events and aggression in a nationwide, school-based sample of adolescents living in rural areas of China. A sample of 13,495 Chinese rural students (7065 boys and 6430 girls; 11-20 years old) was selected from 15 representative rural areas from 5 provinces in China using stratified randomized cluster sampling. Aggression, stressful life events, neglect, emotional management, social support, and demographic characteristics were assessed via self-report questionnaires. Multivariate logistic regressions were used to estimate the association of stressful life events and aggression after controlling for confounds. The prevalence of aggressive behavior among Chinese adolescents living in rural areas was 24.3%. Regression analyses indicated that the odds of aggression were negatively influenced by chronic long-term stressors related to interpersonal problems (OR=2.03, 95% CI [1.75-2.36]), health adaptation difficulties (OR=1.21, 95% CI [1.09-1.34]), and other troubles (OR=1.93, 95% CI [1.74-2.14]), even after adjustment for parental neglect, emotional management, social support, and other relevant factors. This study was cross-sectional; thus, it is necessary to validate the causal relationship between stressful life events and aggression via follow-up studies. Aggression was prevalent among Chinese adolescents living in rural areas, and interpersonal problems, health adaption difficulties, and other troubles were considered potential independent risk factors for aggression. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. The Role of Identity Commitments in Depressive Symptoms and Stressful Life Events in Adolescence and Young Adulthood.

    Science.gov (United States)

    van Doeselaar, Lotte; Klimstra, Theo A; Denissen, Jaap J A; Branje, Susan; Meeus, Wim

    2017-12-18

    The formation of a stable identity, consisting of a strong set of commitments, is a key developmental task in adolescence and young adulthood. Not resolving this task and lacking strong identity commitments is related to difficulties like depressive symptoms and stressful life events. However, the exact role of identity commitments in these negative experiences has remained unclear. In two longitudinal studies in the Netherlands spanning 8 and 6 years, respectively, we examined the associations between career and interpersonal commitments, depressive symptoms, and the number of experienced stressful life events over time. Study 1 included 683 adolescents (11 to 15 years at T1) and 268 adolescents and young adults (16 to 20 years at T1). Study 2 included 960 adolescents (12 to 17 years at T1) and 944 young adults (18 to 24 years at T1). Both studies indicated that stronger identity commitments predicted relative decreases in negative experiences. In Study 2, stronger interpersonal commitments predicted relative decreases in depressive symptoms. In both studies, stronger career commitments predicted a relative decrease in stressful life events. Furthermore, only career commitments weakened after negative experiences. Interpersonal commitments did not weaken after negative experiences, possibly because of the importance of interpersonal relationships during difficult times. Moreover, identity commitments did not buffer the effect of stressful life events on depressive symptoms in either study. These findings underscore the importance of identity commitments in adolescence and young adulthood, but provide crucial nuances regarding their role in different life domains. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  18. Full-field heterodyne dynamic interferometry based on hertz-level low differential-frequency acousto-optic frequency shifter

    Science.gov (United States)

    Wu, Zhou; Zhang, Wenxi; Xiangli, Bin; Kong, Xinxin

    2017-06-01

    High precision measurement of optical elements with long focal length is affected by vibration, airflow and other environmental factors due to the long cavity length, which has been difficulty and hot issue in optical machining and detection. In order to overcome the difficulties of high precision measurement of optical elements with long focal length, the paper proposes a full-field heterodyne interferometric measurement technique that could effectively suppress the environmental interference. In the early related research, a series of Hertz-level high-stability, low-differential frequency acousto-optic frequency shifters were successfully developed, which could be applied to heterodyne interferometry, instead of traditional phase-shifting intererometry. On this basis, a full-field heterodyne interference measurement system is developed, using array detector with conventional frame rate for full-field detection, to solve the problem of different optical paths of reference light and measuring light in dynamic interferometers. It could effectively suppress the vibration, noise, airflow and other factors, and thus significantly improve measurement accuracy and environmental adaptability. In typical environment with vibration and airflow, our measurement system can achieve technical indicators as follows: surface measurement accuracy is better than λ/1000 and repeated measurement accuracy is better than 5λ/10000. Thereby the new full-field heterodyne interferometry could be applied to dynamic measurement of large-diameter optical components and systems quality inspection, system installation correction, on-line measurement and other areas.

  19. Revealing the Formation of Stellar-mass Black Hole Binaries: The Need for Deci-Hertz Gravitational-wave Observatories

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xian [Astronomy Department, School of Physics, Peking University, 100871 Beijing (China); Amaro-Seoane, Pau, E-mail: xian.chen@pku.edu.cn, E-mail: pau@ice.cat [Institut de Ciències de l’Espai (CSIC-IEEC) at Campus UAB, Carrer de Can Magrans s/n, E-08193 Barcelona (Spain)

    2017-06-10

    The formation of compact stellar-mass binaries is a difficult, but interesting problem in astrophysics. There are two main formation channels: in the field via binary star evolution, or in dense stellar systems via dynamical interactions. The Laser Interferometer Gravitational-wave Observatory (LIGO) has detected black hole binaries (BHBs) via their gravitational radiation. These detections provide us with information about the physical parameters of the system. It has been claimed that when the Laser Interferometer Space Antenna (LISA) is operating, the joint observation of these binaries with LIGO will allow us to derive the channels that lead to their formation. However, we show that for BHBs in dense stellar systems dynamical interactions could lead to high eccentricities such that a fraction of the relativistic mergers are not audible to LISA. A non-detection by LISA puts a lower limit of about 0.005 on the eccentricity of a BHB entering the LIGO band. On the other hand, a deci-Hertz observatory, like DECIGO or Tian Qin, would significantly enhance the chances of a joint detection and shed light on the formation channels of these binaries.

  20. The relationship between recent stressful life events, personality traits, perceived family functioning and internet addiction among college students.

    Science.gov (United States)

    Yan, Wansen; Li, Yonghui; Sui, Nan

    2014-02-01

    Internet addiction (IA) is an emerging social and mental health issue among youths. Analysis of risk factors, as well as their interactions, is crucial for understanding the development of IA. This study investigated the relationship between recent stressful life events, personality traits, perceived family functioning and IA in 892 college students. Subjects were classified into categories (non-addicted, mild IA or severe IA) using the Chen Internet Addiction Scale. Stressful life events, personality traits and family functioning were assessed using the Adolescent Self-Rating Life Events Checklist, the Eysenck Personality Questionnaire, and the Family Adaptability and Cohesion Scale, respectively. The results indicated that compared with non-addicted subjects, subjects with severe IA (9.98%) had lower family functioning, lower extraversion, higher neuroticism and psychoticism, and more stressful life events, and subjects with mild IA (11.21%) had higher neuroticism and more health and adaptation problems. Neuroticism and health and adaptation problems were potential predictors of IA. An interaction effect between psychoticism and total life stress on IA was also found. These findings highlight the role of personality traits and life stress and their interactions in college students' IA. Further research should explore the mechanisms underlying the interaction effect of psychoticism with life stress on IA. Copyright © 2013 John Wiley & Sons, Ltd.

  1. Klaus Blaum, of GSI Darmstadt and project leader of the ISOLTRAP experiment at CERN, will receive the 2004 Gustav-Hertz-Prize for his outstanding work on the mass determination of unstable atomic nuclei

    CERN Multimedia

    2004-01-01

    Klaus Blaum, of GSI Darmstadt and project leader of the ISOLTRAP experiment at CERN, will receive the 2004 Gustav-Hertz-Prize for his outstanding work on the mass determination of unstable atomic nuclei

  2. A bodyweight-dependent allometric exponent for scaling clearance across the human life-span.

    Science.gov (United States)

    Wang, Chenguang; Peeters, Mariska Y M; Allegaert, Karel; Blussé van Oud-Alblas, Heleen J; Krekels, Elke H J; Tibboel, Dick; Danhof, Meindert; Knibbe, Catherijne A J

    2012-06-01

    To explore different allometric equations for scaling clearance across the human life-span using propofol as a model drug. Data from seven previously published propofol studies ((pre)term neonates, infants, toddlers, children, adolescents and adults) were analysed using NONMEM VI. To scale clearance, a bodyweight-based exponential equation with four different structures for the exponent was used: (I) 3/4 allometric scaling model; (II) mixture model; (III) bodyweight-cut-point separated model; (IV) bodyweight-dependent exponent model. Model I adequately described clearance in adults and older children, but overestimated clearance of neonates and underestimated clearance of infants. Use of two different exponents in Model II and Model III showed significantly improved performance, but yielded ambiguities on the boundaries of the two subpopulations. This discontinuity was overcome in Model IV, in which the exponent changed sigmoidally from 1.35 at a hypothetical bodyweight of 0 kg to a value of 0.56 from 10 kg onwards, thereby describing clearance of all individuals best. A model was developed for scaling clearance over the entire human life-span with a single continuous equation, in which the exponent of the bodyweight-based exponential equation varied with bodyweight.

  3. Gender Differences in Stressful Life Events, Social Support, Perceived Stress, and Alcohol Use Among Older Adults: Results From a National Survey

    OpenAIRE

    Sacco, Paul; Bucholz, Kathleen K.; Harrington, Donna

    2013-01-01

    Stressful life events, perceived stress, and social support relationships with consumption, at-risk drinking, and alcohol use disorder (AUD) were studied in a population-based sample of current drinkers age 60+ in the National Epidemiologic Survey of Alcohol and Related Conditions (Wave 2; 2004–2005; n = 4,360). Stressful life events were associated with AUD among men and women, and crime victimization among men only. However, greater perceived stress was associated with lower consumption amo...

  4. Stochastic model of Zipf's law and the universality of the power-law exponent.

    Science.gov (United States)

    Yamamoto, Ken

    2014-04-01

    We propose a stochastic model of Zipf's law, namely a power-law relation between rank and size, and clarify as to why a specific value of its power-law exponent is quite universal. We focus on the successive total of a multiplicative stochastic process. By employing properties of a well-known stochastic process, we concisely show that the successive total follows a stationary power-law distribution, which is directly related to Zipf's law. The formula of the power-law exponent is also derived. Finally, we conclude that the universality of the rank-size exponent is brought about by symmetry between an increase and a decrease in the random growth rate.

  5. Non-mean-field critical exponent in a mean-field model: dynamics versus statistical mechanics.

    Science.gov (United States)

    Ogawa, Shun; Patelli, Aurelio; Yamaguchi, Yoshiyuki Y

    2014-03-01

    Mean-field theory tells us that the classical critical exponent of susceptibility is twice that of magnetization. However, linear response theory based on the Vlasov equation, which is naturally introduced by the mean-field nature, makes the former exponent half of the latter for families of quasistationary states having second order phase transitions in the Hamiltonian mean-field model and its variances, in the low-energy phase. We clarify that this strange exponent is due to the existence of Casimir invariants which trap the system in a quasistationary state for a time scale diverging with the system size. The theoretical prediction is numerically confirmed by N-body simulations for the equilibrium states and a family of quasistationary states.

  6. Statistical properties of a dissipative kicked system: Critical exponents and scaling invariance

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Diego F.M., E-mail: diegofregolente@gmail.com [CAMTP – Center for Applied Mathematics and Theoretical Physics, University of Maribor, Krekova 2, SI-2000 Maribor (Slovenia); Robnik, Marko, E-mail: robnik@uni-mb.si [CAMTP – Center for Applied Mathematics and Theoretical Physics, University of Maribor, Krekova 2, SI-2000 Maribor (Slovenia); Leonel, Edson D., E-mail: edleonel@rc.unesp.br [Departamento de Estatística, Matemática Aplicada e Computação, UNESP – Universidade Estadual Paulista, Av. 24A, 1515, Bela Vista, 13506-900 Rio Claro, SP (Brazil)

    2012-01-16

    A new universal empirical function that depends on a single critical exponent (acceleration exponent) is proposed to describe the scaling behavior in a dissipative kicked rotator. The scaling formalism is used to describe two regimes of dissipation: (i) strong dissipation and (ii) weak dissipation. For case (i) the model exhibits a route to chaos known as period doubling and the Feigenbaum constant along the bifurcations is obtained. When weak dissipation is considered the average action as well as its standard deviation are described using scaling arguments with critical exponents. The universal empirical function describes remarkably well a phase transition from limited to unlimited growth of the average action. -- Highlights: ► A new universal empirical function is proposed. ► The scaling formalism is used to describe two regimes of dissipation. ► The model exhibits a route to chaos known as period doubling. ► The average action as well as its standard deviation are described using scaling.

  7. Critical Exponents, Scaling Law, Universality and Renormalization Group Flow in Strong Coupling QED

    Science.gov (United States)

    Kondo, Kei-Ichi

    The critical behavior of strongly coupled QED with a chiral-invariant four-fermion interaction (gauged Nambu-Jona-Lasinio model) is investigated through the unquenched Schwinger-Dyson equation including the fermion loop effect at the one-loop level. It is shown that the critical exponents satisfy the (hyper)scaling relations as in the quenched case. However, the respective critical exponent takes the classical mean-field value, and consequently unquenched QED belongs to the same universality class as the zero-charge model. On the other hand, it is pointed out that quenched QED violates not only universality but also weak universality, due to continuously varying critical exponents. Furthermore, the renormalization group flow of constant renormalized charge is given. All the results are consistent with triviality of QED and the gauged Nambu-Jona-Lasinio model in the unquenched case.

  8. Identification of exponent from load-deformation relation for soft materials from impact tests

    Science.gov (United States)

    Ciornei, F. C.; Alaci, S.; Romanu, I. C.; Ciornei, M. C.; Sopon, G.

    2018-01-01

    When two bodies are brought into contact, the magnitude of occurring reaction forces increase together with the amplitude of deformations. The load-deformation dependency of two contacting bodies is described by a function having the form F = Cxα . An accurate illustration of this relationship assumes finding the precise coefficient C and exponent α. This representation proved to be very useful in hardness tests, in dynamic systems modelling or in considerations upon the elastic-plastic ratio concerning a Hertzian contact. The classical method for identification of the exponent consists in finding it from quasi-static tests. The drawback of the method is the fact that the accurate estimation of the exponent supposes precise identification of the instant of contact initiation. To overcome this aspect, the following observation is exploited: during an impact process, the dissipated energy is converted into heat released by internal friction in the materials and energy for plastic deformations. The paper is based on the remark that for soft materials the hysteresis curves obtained for a static case are similar to the ones obtained for medium velocities. Furthermore, utilizing the fact that for the restitution phase the load-deformation dependency is elastic, a method for finding the α exponent for compression phase is proposed. The maximum depth of the plastic deformations obtained for a series of collisions, by launching, from different heights, a steel ball in free falling on an immobile prism made of soft material, is evaluated by laser profilometry method. The condition that the area of the hysteresis loop equals the variation of kinetical energy of the ball is imposed and two tests are required for finding the exponent. Five collisions from different launching heights of the ball were taken into account. For all the possible impact-pair cases, the values of the exponent were found and close values were obtained.

  9. Bayesian estimation of the self-similarity exponent of the Nile River fluctuation

    Directory of Open Access Journals (Sweden)

    S. Benmehdi

    2011-06-01

    Full Text Available The aim of this paper is to estimate the Hurst parameter of Fractional Gaussian Noise (FGN using Bayesian inference. We propose an estimation technique that takes into account the full correlation structure of this process. Instead of using the integrated time series and then applying an estimator for its Hurst exponent, we propose to use the noise signal directly. As an application we analyze the time series of the Nile River, where we find a posterior distribution which is compatible with previous findings. In addition, our technique provides natural error bars for the Hurst exponent.

  10. Effects of length fluctuations on the viscosity exponent in the necklace model

    Energy Technology Data Exchange (ETDEWEB)

    Aldao, C M [Institute of Materials Science and Technology (INTEMA), Universidad Nacional de Mar del Plata-CONICET, Juan B Justo 4302, B7608FDQ Mar del Plata (Argentina); Terranova, G R; Martin, H O [Physics Department, School of Exact and Natural Sciences, Universidad Nacional de Mar del Plata, Dean Funes 3350, B7602AYL Mar del Plata (Argentina)

    2009-04-24

    It is commonly accepted that contour length fluctuations increase the viscosity exponent for chains that diffuse by reptation. We found that length fluctuations in the necklace model can play an unexpected role as they can also decrease this exponent. A detailed analysis of the interplay between the discrete character of the model and how the fluctuations take place is presented in this work. Basically, we found that when fluctuations are symmetric their influence is the expected one; when fluctuations are not symmetric new effects can appear.

  11. Brief communication: Possible explanation of the values of Hack's drainage basin, river length scaling exponent

    Science.gov (United States)

    Hunt, Allen G.

    2016-04-01

    Percolation theory can be used to find water flow paths of least resistance. Application of percolation theory to drainage networks allows identification of the range of exponent values that describe the tortuosity of rivers in real river networks, which is then used to generate the observed scaling between drainage basin area and channel length, a relationship known as Hack's law. Such a theoretical basis for Hack's law may allow interpretation of the range of exponent values based on an assessment of the heterogeneity of the substrate.

  12. The susceptibility critical exponent for a nonaqueous ionic binary mixture near a consolute point

    Science.gov (United States)

    Zhang, Kai C.; Briggs, Matthew E.; Gammon, Robert W.; Levelt Sengers, J. M. H.

    1992-01-01

    We report turbidity measurements of a nonaqueous ionic solution of triethyl n-hexylammonium triethyl n-hexylboride in diphenyl ether. A classical susceptibility critical exponent gamma = 1.01 +/- 0.01 is obtained over the reduced temperature range t between values of 0.1 and 0.0001. The best fits of the sample transmission had a standard deviation of 0.39 percent over this range. Ising and spherical model critical exponents are firmly excluded. The correlation length amplitude xi sub 0 from fitting is 1.0 +/- 0.2 nm which is much larger than values found in neutral fluids and some aqueous binary mixtures.

  13. Phase transitions at electrochemical interfaces:. Evaluation of critical exponents for condensation of organic adsorbates

    Science.gov (United States)

    Pushpalatha, K.; Sangaranarayanan, M. V.

    1998-05-01

    The surface pressure exerted by a monolayer of organic compounds condensing at electrochemical interfaces is evaluated using a two-dimensional nearest-neighbor Ising model formalism. The experimental critical temperature data of organic adsorbates are employed to obtain the composite short-range interaction energy using Onsager's exact solution. The methodology of obtaining the critical exponents ` δ' and ` γ' pertaining to surface pressure and isothermal compressibility is discussed. These values are consistent with the exponents postulated in other contexts, thereby demonstrating the universality hypothesis.

  14. An Isomorphism between Lyapunov Exponents and Shannon's Channel Capacity

    Energy Technology Data Exchange (ETDEWEB)

    Friedland, Gerald [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Metere, Alfredo [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-06-07

    We demonstrate that discrete Lyapunov exponents are isomorphic to numeric overflows of the capacity of an arbitrary noiseless and memoryless channel in a Shannon communication model with feedback. The isomorphism allows the understanding of Lyapunov exponents in terms of Information Theory, rather than the traditional definitions in chaos theory. The result also implies alternative approaches to the calculation of related quantities, such as the Kolmogorov Sinai entropy which has been linked to thermodynamic entropy. This work provides a bridge between fundamental physics and information theory. It suggests, among other things, that machine learning and other information theory methods can be employed at the core of physics simulations.

  15. Extracting critical exponents for sequences of numerical data via series extrapolation techniques.

    Science.gov (United States)

    Cöster, Kris; Schmidt, Kai Phillip

    2016-08-01

    We describe a generic scheme to extract critical exponents of quantum lattice models from sequences of numerical data, which is, for example, relevant for nonperturbative linked-cluster expansions or nonperturbative variants of continuous unitary transformations. The fundamental idea behind our approach is a reformulation of the numerical data sequences as a series expansion in a pseudoparameter. This allows us to utilize standard series expansion extrapolation techniques to extract critical properties such as critical points and critical exponents. The approach is illustrated for the deconfinement transition of the antiferromagnetic spin-1/2 Heisenberg chain.

  16. Explanation of the values of Hack's drainage basin, river length scaling exponent

    Science.gov (United States)

    Hunt, A. G.

    2015-08-01

    Percolation theory can be used to find water flow paths of least resistance. The application of percolation theory to drainage networks allows identification of the range of exponent values that describe the tortuosity of rivers in real river networks, which is then used to generate the observed scaling between drainage basin area and channel length, a relationship known as Hack's law. Such a theoretical basis for Hack's law allows interpretation of the range of exponent values based on an assessment of the heterogeneity of the substrate.

  17. Hartree-Fock energy derivatives with respect to basis set exponents. Integral derivatives using Rys polynomials

    Science.gov (United States)

    Tonachini, Glauco; Schlegel, H. Bernhard

    1987-07-01

    The Rys polynomial method has been used to evaluate the first derivatives of the two electron integrals and the nuclear electron attraction integrals with respect to the Gaussian exponents. Gradients for the sulfur 6-31 G(d) basis set in HS-, H2S, H3S+, H2S2, H3CSH, H2CS, CS, H2SO, SO2 and SO3 have been evaluated to illustrate the effect of charge, multiple bonding and hypervalency on the basis set exponents.

  18. Quantifying the intermittency independent scaling exponents in the anisotropic solar wind.

    Science.gov (United States)

    Chapman, S. C.; Hnat, B.

    2006-12-01

    Solar wind turbulence is dominated by Alfvenic fluctuations with power spectral exponents that somewhat surprisingly evolve toward the Kolmogorov value of -5/3, that of hydrodynamic turbulence. We analyse a 3 year interval of ACE data that is dominated by slow solar wind and show that at 1AU the turbulence decomposes linearly into two coexistent components perpendicular and parallel to the local average magnetic field and determine the distinct intermittency independent scaling exponents. The first of these is consistent with recent predictions for anisotropic MHD and the second shows Kolmogorov-like scaling which we also find in the number and magnetic energy density, and Poynting flux.

  19. Langevin Simulations of Two Dimensional Vortex Fluctuations Anomalous Dynamics and a New $IV$-exponent

    CERN Document Server

    Holmlund, K; Holmlund, Kenneth; Minnhagen, Petter

    1995-01-01

    The dynamics of two dimensional (2D) vortex fluctuations are investigated through simulations of the 2D Coulomb gas model in which vortices are represented by soft disks with logarithmic interactions. The simulations trongly support a recent suggestion that 2D vortex fluctuations obey an intrinsic anomalous dynamics manifested in a long range 1/t-tail in the vortex correlations. A new non-linear IV-exponent a, which is different from the commonly used AHNS exponent, a_AHNS and is given by a = 2a_AHNS - 3, is confirmed by the simulations. The results are discussed in the context of earlier simulations, experiments and a phenomenological description.

  20. Culture and context: buffering the relationship between stressful life events and risky behaviors in American Indian youth.

    Science.gov (United States)

    Baldwin, Julie A; Brown, Betty G; Wayment, Heidi A; Nez, Ramona Antone; Brelsford, Kathleen M

    2011-01-01

    The Sacred Mountain Youth Project was conducted to investigate risk and protective factors related to alcohol and drug use among American Indian youth. Findings indicated that stressful life events were positively associated with depressed mood, substance use, and risky behavior; cultural identity had no direct effects, but a secondary model showed that social support and protective family and peer influences were related to cultural identity. These findings suggest that the relationships between stressors and their negative sequelae are complex. Emphasis on protective processes that are culturally specific to American Indian youth may lead to effective alcohol and drug use prevention programs.

  1. Regional and national differences in stressful life events: The role of cultural factors, economic development, and gender.

    Science.gov (United States)

    Vázquez, José Juan; Panadero, Sonia; Martín, Rosa M

    2015-07-01

    The study analyzed differences in the risk of experiencing stressful life events (SLE) according to cultural factors, the level of economic development of the region inhabited, and gender. Information was gathered on the number and nature of SLE experienced by a sample of 604 undergraduates from 3 regions with very different levels of economic development: Madrid (Spain), León (Nicaragua), and Bilwi (Nicaragua). The results indicated a greater risk of experiencing SLE among undergraduates from Nicaragua, but few differences attributed to the undergraduates' gender or the level of economic development in the region they inhabit within the same country. (c) 2015 APA, all rights reserved).

  2. On Ultrafast Time-Domain TeraHertz Spectroscopy in the Condensed Phase: Linear Spectroscopic Measurements of Hydrogen-Bond Dynamics of Astrochemical Ice Analogs and Nonlinear TeraHertz Kerr Effect Measurements of Vibrational Quantum Beats

    Science.gov (United States)

    Allodi, Marco A.

    Much of the chemistry that affects life on planet Earth occurs in the condensed phase. The TeraHertz (THz) or far-infrared (far-IR) region of the electromagnetic spectrum (from 0.1 THz to 10 THz) has been shown to provide unique possibilities in the study of condensed-phase processes. The goal of this work is to expand the possibilities available in the THz region and undertake new investigations of fundamental interest to chemistry. Since we are fundamentally interested in condensed-phase processes, this thesis focuses on two areas where THz spectroscopy can provide new understanding: astrochemistry and solvation science. To advance these fields, we had to develop new instrumentation that would enable the experiments necessary to answer new questions in either astrochemistry or solvation science. We first developed a new experimental setup capable of studying astrochemical ice analogs in both the TeraHertz (THz), or far-Infrared (far-IR), region (0.3 - 7.5 THz; 10 - 250 wavenumbers) and the mid-IR (400 - 4000 wavenumbers). The importance of astrochemical ices lies in their key role in the formation of complex organic molecules, such as amino acids and sugars in space. Thus, the instruments are capable of performing variety of spectroscopic studies that can provide especially relevant laboratory data to support astronomical observations from telescopes such as the Herschel Space Telescope, the Stratospheric Observatory for Infrared Astronomy (SOFIA), and the Atacama Large Millimeter Array (ALMA). The experimental apparatus uses a THz time-domain spectrometer, with a 1750/875 nm plasma source and a GaP detector crystal, to cover the bandwidth mentioned above with 10 GHz (0.3 wavenumber) resolution. Using the above instrumentation, experimental spectra of astrochemical ice analogs of water and carbon dioxide in pure, mixed, and layered ices were collected at different temperatures under high-vacuum conditions with the goal of investigating the structure of the ice

  3. Effect of interband interaction on isotope effect exponent of MgB2 ...

    Indian Academy of Sciences (India)

    com. MS received 22 September 2004; revised 5 January 2006; accepted 24 January 2005. Abstract. The exact formula of Tc's equation and the isotope effect exponent of two- band s-wave superconductors in the weak-coupling limit are ...

  4. High-resolution satellite image segmentation using Hölder exponents

    Indian Academy of Sciences (India)

    Hölder exponent values (noise or not associated with the other cluster) are clubbed to a nearest possible cluster using the local maximum likelihood analysis. 1. Introduction. The spectral or pixel-based segmentation technique consists of K-Means (Hartigan et al 1979), Fuzzy. C Means (Bezdek et al 1984) and methods of.

  5. External neutron source anomalies analysis using Hurst's exponent for the Myrrha reactor

    Energy Technology Data Exchange (ETDEWEB)

    Henrice Junior, Edson; Goncalves, Alessandro C., E-mail: ejunior@con.ufrj.br [Coordenacao dos Cursos de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Nuclear; Palma, Daniel A.P., E-mail: dapalma@cnen.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeir, RJ (Brazil)

    2015-07-01

    Anomalous diffusion is usually marked by the non-linear growth of the variance in time, that is, the diffusion will be considered as anomalous if there is a deviation in the behaviour described before. This paper aims to identify anomalies in the neutron flux during the operation of an ADS (Accelerator Driven System) nuclear reactor as a result of a trip that originates in the proton accelerator as per project bases, from two different calculation methods for Hurst exponents. These methods are the R/S Method and the Detrended Fluctuation Analysis (DFA) Method. For that the Myrrha Reactor will be simulated using the SERPENT code and the neutron source will be subjected to a production peak at a given instant. The Hurst exponent has a direct application on determining the order of derivatives in fractional point-kinetics equations and the estimate for the fractional derivative can be related as being twice that of Hurst's exponent, according to the co-variance function in the Gauss' processes. After getting the Hurst's exponent a numerically solution is proposed. This subject being a theme very much in focus nowadays. (author)

  6. Phase space reconstruction and estimation of the largest Lyapunov exponent for gait kinematic data

    Energy Technology Data Exchange (ETDEWEB)

    Josiński, Henryk [Silesian University of Technology, Akademicka 16, 44-100 Gliwice (Poland); Świtoński, Adam [Polish-Japanese Institute of Information Technology, Aleja Legionów 2, 41-902 Bytom (Poland); Silesian University of Technology, Akademicka 16, 44-100 Gliwice (Poland); Michalczuk, Agnieszka; Wojciechowski, Konrad [Polish-Japanese Institute of Information Technology, Aleja Legionów 2, 41-902 Bytom (Poland)

    2015-03-10

    The authors describe an example of application of nonlinear time series analysis directed at identifying the presence of deterministic chaos in human motion data by means of the largest Lyapunov exponent. The method was previously verified on the basis of a time series constructed from the numerical solutions of both the Lorenz and the Rössler nonlinear dynamical systems.

  7. Predicting Traffic Flow in Local Area Networks by the Largest Lyapunov Exponent

    Directory of Open Access Journals (Sweden)

    Yan Liu

    2016-01-01

    Full Text Available The dynamics of network traffic are complex and nonlinear, and chaotic behaviors and their prediction, which play an important role in local area networks (LANs, are studied in detail, using the largest Lyapunov exponent. With the introduction of phase space reconstruction based on the time sequence, the high-dimensional traffic is projected onto the low dimension reconstructed phase space, and a reduced dynamic system is obtained from the dynamic system viewpoint. Then, a numerical method for computing the largest Lyapunov exponent of the low-dimensional dynamic system is presented. Further, the longest predictable time, which is related to chaotic behaviors in the system, is studied using the largest Lyapunov exponent, and the Wolf method is used to predict the evolution of the traffic in a local area network by both Dot and Interval predictions, and a reliable result is obtained by the presented method. As the conclusion, the results show that the largest Lyapunov exponent can be used to describe the sensitivity of the trajectory in the reconstructed phase space to the initial values. Moreover, Dot Prediction can effectively predict the flow burst. The numerical simulation also shows that the presented method is feasible and efficient for predicting the complex dynamic behaviors in LAN traffic, especially for congestion and attack in networks, which are the main two complex phenomena behaving as chaos in networks.

  8. Directional maximum likelihood self-estimation of the path-loss exponent

    NARCIS (Netherlands)

    Hu, Y.; Leus, G.J.T.; Dong, Min; Zheng, Thomas Fang

    2016-01-01

    The path-loss exponent (PLE) is a key parameter in wireless propagation channels. Therefore, obtaining the knowledge of the PLE is rather significant for assisting wireless communications and networking to achieve a better performance. Most existing methods for estimating the PLE not only require

  9. Using machine learning to replicate chaotic attractors and calculate Lyapunov exponents from data

    Science.gov (United States)

    Pathak, Jaideep; Lu, Zhixin; Hunt, Brian R.; Girvan, Michelle; Ott, Edward

    2017-12-01

    We use recent advances in the machine learning area known as "reservoir computing" to formulate a method for model-free estimation from data of the Lyapunov exponents of a chaotic process. The technique uses a limited time series of measurements as input to a high-dimensional dynamical system called a "reservoir." After the reservoir's response to the data is recorded, linear regression is used to learn a large set of parameters, called the "output weights." The learned output weights are then used to form a modified autonomous reservoir designed to be capable of producing an arbitrarily long time series whose ergodic properties approximate those of the input signal. When successful, we say that the autonomous reservoir reproduces the attractor's "climate." Since the reservoir equations and output weights are known, we can compute the derivatives needed to determine the Lyapunov exponents of the autonomous reservoir, which we then use as estimates of the Lyapunov exponents for the original input generating system. We illustrate the effectiveness of our technique with two examples, the Lorenz system and the Kuramoto-Sivashinsky (KS) equation. In the case of the KS equation, we note that the high dimensional nature of the system and the large number of Lyapunov exponents yield a challenging test of our method, which we find the method successfully passes.

  10. Upper and lower critical decay exponents of Ising ferromagnets with long-range interaction.

    Science.gov (United States)

    Horita, Toshiki; Suwa, Hidemaro; Todo, Synge

    2017-01-01

    We investigate the universality class of the finite-temperature phase transition of the two-dimensional Ising model with the algebraically decaying ferromagnetic long-range interaction, J_{ij}=|r[over ⃗]_{i}-r[over ⃗]_{j}|^{-(d+σ)}, where d (=2) is the dimension of the system and σ is the decay exponent, by means of the order-N cluster-algorithm Monte Carlo method. In particular, we focus on the upper and lower critical decay exponents, the boundaries between the mean-field-universality, intermediate, and short-range-universality regimes. At the critical decay exponents, it is found that the standard Binder ratio of magnetization at the critical temperature exhibits extremely slow convergence as a function of the system size. We propose more effective physical quantities, namely the combined Binder ratio and the self-combined Binder ratio, both of which cancel the leading finite-size corrections of the conventional Binder ratio. Utilizing these techniques, we clearly demonstrate that in two dimensions, the lower and upper critical decay exponents are σ=1 and 7/4, respectively, contrary to the recent Monte Carlo and renormalization-group studies [M. Picco, arXiv:1207.1018; T. Blanchard et al., Europhys. Lett. 101, 56003 (2013)EULEEJ0295-507510.1209/0295-5075/101/56003].

  11. Critical exponents in the transition to chaos in one-dimensional ...

    Indian Academy of Sciences (India)

    We report the numerically evaluated critical exponents associated with the scaling of generalized fractal dimensions during the transition from order to chaos. The analysis is carried out in detail in the context of unimodal and bimodal maps representing typical one-dimensional discrete dynamical systems. The behavior of ...

  12. Compactness results for quasilinear problems with variable exponent on the whole space

    Directory of Open Access Journals (Sweden)

    Olfa Allegue

    2011-07-01

    Full Text Available In this work we give a compactness result which allows us to prove the point-wise convergence of the gradients of a sequence of solutions to a quasilinear inequality and for an arbitrary open set. This result suggests solutions to many problems, notably nonlinear elliptic problems with critical exponent.

  13. Stressful life transitions and wellbeing: A comparison of the stress buffering hypothesis and the social identity model of identity change.

    Science.gov (United States)

    Praharso, Nurul F; Tear, Morgan J; Cruwys, Tegan

    2017-01-01

    The relationship between stressful life transitions and wellbeing is well established, however, the protective role of social connectedness has received mixed support. We test two theoretical models, the Stress Buffering Hypothesis and the Social Identity Model of Identity Change, to determine which best explains the relationship between social connectedness, stress, and wellbeing. Study 1 (N=165) was an experiment in which participants considered the impact of moving cities versus receiving a serious health diagnosis. Study 2 (N=79) was a longitudinal study that examined the adjustment of international students to university over the course of their first semester. Both studies found limited evidence for the buffering role of social support as predicted by the Stress Buffering Hypothesis; instead people who experienced a loss of social identities as a result of a stressor had a subsequent decline in wellbeing, consistent with the Social Identity Model of Identity Change. We conclude that stressful life events are best conceptualised as identity transitions. Such events are more likely to be perceived as stressful and compromise wellbeing when they entail identity loss. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. Stressful life events and the onset of chronic diseases among Australian adults: findings from a longitudinal survey.

    Science.gov (United States)

    Renzaho, Andre M N; Houng, Brendan; Oldroyd, John; Nicholson, Jan M; D'Esposito, Fabrizio; Oldenburg, Brian

    2014-02-01

    This article examines the link between stressful life events and illness by considering both onset and reoccurrence of chronic illnesses. Using longitudinal data, we estimate the extent to which life events increase the likelihood of depression or anxiety, type 2 diabetes, cancer, coronary heart disease, circulatory disease, asthma and emphysema among Australian adults aged ≥21 years. Longitudinal data were obtained from the nationally representative Household, Income and Labour Dynamics in Australia panel survey collected at waves 3 (2003), 7 (2007) and 9 (2009). Participants (N = 9222) answered life events questions relating to the preceding 12 months and chronic illnesses lasting (or expected to last for) 6 months. Weighted pooled and random effects logistic regressions were performed, controlling for confounders and previous illness, and also performed on subsamples delineated by reported illnesses in wave 3. Work-related stress [odds ratio (OR) = 1.54, P depression or anxiety. Personal stress increased the likelihood of the onset of depression or anxiety (OR = 1.70, P diabetes (OR = 1.47, P related stress increased the likelihood of the onset of heart (OR = 1.32, P related, personal and family-related stressful life events contribute to the development and/or course of chronic diseases.

  15. Inter-relationship between scaling exponents for describing self-similar river networks

    Science.gov (United States)

    Yang, Soohyun; Paik, Kyungrock

    2015-04-01

    Natural river networks show well-known self-similar characteristics. Such characteristics are represented by various power-law relationships, e.g., between upstream length and drainage area (exponent h) (Hack, 1957), and in the exceedance probability distribution of upstream area (exponent ɛ) (Rodriguez-Iturbe et al., 1992). It is empirically revealed that these power-law exponents are within narrow ranges. Power-law is also found in the relationship between drainage density (the total stream length divided by the total basin area) and specified source area (the minimum drainage area to form a stream head) (exponent η) (Moussa and Bocquillon, 1996). Considering that above three scaling relationships all refer to fundamental measures of 'length' and 'area' of a given drainage basin, it is natural to hypothesize plausible inter-relationship between these three scaling exponents. Indeed, Rigon et al. (1996) demonstrated the relationship between ɛ and h. In this study, we expand this to a more general ɛ-η-h relationship. We approach ɛ-η relationship in an analytical manner while η-h relationship is demonstrated for six study basins in Korea. Detailed analysis and implications will be presented. References Hack, J. T. (1957). Studies of longitudinal river profiles in Virginia and Maryland. US, Geological Survey Professional Paper, 294. Moussa, R., & Bocquillon, C. (1996). Fractal analyses of tree-like channel networks from digital elevation model data. Journal of Hydrology, 187(1), 157-172. Rigon, R., Rodriguez-Iturbe, I., Maritan, A., Giacometti. A., Tarboton, D. G., & Rinaldo, A. (1996). On Hack's Law. Water Resources Research, 32(11), 3367-3374. Rodríguez-Iturbe, I., Ijjasz-Vasquez, E. J., Bras, R. L., & Tarboton, D. G. (1992). Power law distributions of discharge mass and energy in river basins. Water Resources Research, 28(4), 1089-1093.

  16. Rolling Bearing Life Prediction, Theory, and Application

    Science.gov (United States)

    Zaretsky, Erwin V.

    2013-01-01

    A tutorial is presented outlining the evolution, theory, and application of rolling-element bearing life prediction from that of A. Palmgren, 1924; W. Weibull, 1939; G. Lundberg and A. Palmgren, 1947 and 1952; E. Ioannides and T. Harris, 1985; and E. Zaretsky, 1987. Comparisons are made between these life models. The Ioannides-Harris model without a fatigue limit is identical to the Lundberg-Palmgren model. The Weibull model is similar to that of Zaretsky if the exponents are chosen to be identical. Both the load-life and Hertz stress-life relations of Weibull, Lundberg and Palmgren, and Ioannides and Harris reflect a strong dependence on the Weibull slope. The Zaretsky model decouples the dependence of the critical shear stress-life relation from the Weibull slope. This results in a nominal variation of the Hertz stress-life exponent. For 9th- and 8th-power Hertz stress-life exponents for ball and roller bearings, respectively, the Lundberg- Palmgren model best predicts life. However, for 12th- and 10th-power relations reflected by modern bearing steels, the Zaretsky model based on the Weibull equation is superior. Under the range of stresses examined, the use of a fatigue limit would suggest that (for most operating conditions under which a rolling-element bearing will operate) the bearing will not fail from classical rolling-element fatigue. Realistically, this is not the case. The use of a fatigue limit will significantly overpredict life over a range of normal operating Hertz stresses. Since the predicted lives of rolling-element bearings are high, the problem can become one of undersizing a bearing for a particular application.

  17. Fractional Black–Scholes option pricing, volatility calibration and implied Hurst exponents in South African context

    Directory of Open Access Journals (Sweden)

    Emlyn Flint

    2017-03-01

    Full Text Available Background: Contingent claims on underlying assets are typically priced under a framework that assumes, inter alia, that the log returns of the underlying asset are normally distributed. However, many researchers have shown that this assumption is violated in practice. Such violations include the statistical properties of heavy tails, volatility clustering, leptokurtosis and long memory. This paper considers the pricing of contingent claims when the underlying is assumed to display long memory, an issue that has heretofore not received much attention. Aim: We address several theoretical and practical issues in option pricing and implied volatility calibration in a fractional Black–Scholes market. We introduce a novel eight-parameter fractional Black–Scholes-inspired (FBSI model for the implied volatility surface, and consider in depth the issue of calibration. One of the main benefits of such a model is that it allows one to decompose implied volatility into an independent long-memory component – captured by an implied Hurst exponent – and a conditional implied volatility component. Such a decomposition has useful applications in the areas of derivatives trading, risk management, delta hedging and dynamic asset allocation. Setting: The proposed FBSI volatility model is calibrated to South African equity index options data as well as South African Rand/American Dollar currency options data. However, given the focus on the theoretical development of the model, the results in this paper are applicable across all financial markets. Methods: The FBSI model essentially combines a deterministic function form of the 1-year implied volatility skew with a separate deterministic function for the implied Hurst exponent, thus allowing one to model both observed implied volatility surfaces as well as decompose them into independent volatility and long-memory components respectively. Calibration of the model makes use of a quasi-explicit weighted

  18. Time-Domain TeraHertz Spectroscopy and Observational Probes of Prebiotic Interstellar Gas and Ice Chemistry

    Science.gov (United States)

    McGuire, Brett Andrew

    ruled out a gas-phase route to the synthesis of the simplest amino acid in the ISM. A molecular mystery in the case of the carrier of a series of transitions was resolved using observational data toward a large number of sources, confirming the identity of this important carbon-chemistry intermediate B11244 as l-C3H+ and identifying it in at least two new environments. Finally, the doubly-nitrogenated molecule carbodiimide HNCNH was identified in the ISM for the first time through maser emission features in the centimeter-wavelength regime. In the laboratory, a TeraHertz Time-Domain Spectrometer was constructed to obtain the experimental spectra necessary to search for solid-phase species in the ISM in the THz region of the spectrum. These investigations have shown a striking dependence on large-scale, long-range (i.e. lattice) structure of the ices on the spectra they present in the THz. A database of molecular spectra has been started, and both the simplest and most abundant ice species, which have already been identified, as well as a number of more complex species, have been studied. The exquisite sensitivity of the THz spectra to both the structure and thermal history of these ices may lead to better probes of complex chemical and dynamical evolution in interstellar environments.

  19. The Role of Rumination and Stressful Life Events in the Relationship between the Qi Stagnation Constitution and Depression in Women: A Moderated Mediation Model

    Directory of Open Access Journals (Sweden)

    Mingfan Liu

    2017-01-01

    Full Text Available The qi stagnation constitution is associated with depression in traditional Chinese medicine. It is unclear how rumination and stressful life events affect the relationship between the qi stagnation constitution and depression. The Qi Stagnation Constitution Scale, Ruminative Response Scale, Center for Epidemiologic Studies Depression Scale, and Adolescent Self-Rating Life Events Checklist were used to assess this association in 1200 female college students. The results revealed that the qi stagnation constitution was positively associated with depression. Furthermore, rumination was a partial mediator of the relationship between the qi stagnation constitution and depression. In addition, stressful life events moderated the direct effect and mediating effect of the qi stagnation constitution on depression. These findings indicate that rumination and stressful life events may affect the relationship between the qi stagnation constitution and depression in women.

  20. HIV infection, stressful life events, and intimate relationship power: the moderating role of community resources for black South African women.

    Science.gov (United States)

    Ketchen, Bethany; Armistead, Lisa; Cook, Sarah

    2009-01-01

    Black women in South Africa are vulnerable with limited power in intimate relationships. This study explored whether stressful life events and/or HIV infection were associated with relationship power and whether the impact was moderated by community resources. One hundred four women living with HIV and 152 women not living with HIV participated in individual interviews. Undesirable life changes were negatively associated with relationship control. HIV infection and women's knowledge of community resources were associated with mutual decision-making, while frequency of family use of community resources was negatively related to female dominated decisions. Women living with HIV perceived their male partners as less dominant when they perceived their community resources to be more helpful. Power in intimate relationships may enhance the quality and length of life for black South African women living with HIV. Knowledge of and perceived helpfulness of community resources are avenues for promoting relationship power.

  1. The impact of stressful life events on excessive alcohol consumption in the French population: findings from the GAZEL cohort study.

    Science.gov (United States)

    Tamers, Sara L; Okechukwu, Cassandra; Bohl, Alex A; Guéguen, Alice; Goldberg, Marcel; Zins, Marie

    2014-01-01

    Major life changes may play a causative role in health through lifestyle factors, such as alcohol. The objective was to examine the impact of stressful life events on heavy alcohol consumption among French adults. Trajectories of excessive alcohol consumption in 20,625 employees of the French national gas and electricity company for up to 5 years before and 5 years after an event, with annual measurements from 1992. We used repeated measures analysis of time series data indexed to events, employing generalized estimating equations. For women, excessive alcohol use increased before important purchase (p = 0.021), children leaving home (pdivorce, widowhood, and death of loved one (all pdivorce and increased after (all pimpact alcohol intake temporarily while others have longer-term implications. Research should disentangle women's and men's distinct perceptions of events over time.

  2. Extracting Lyapunov exponents from the echo dynamics of Bose-Einstein condensates on a lattice

    Science.gov (United States)

    Tarkhov, Andrei E.; Wimberger, Sandro; Fine, Boris V.

    2017-08-01

    We propose theoretically an experimentally realizable method to demonstrate the Lyapunov instability and to extract the value of the largest Lyapunov exponent for a chaotic many-particle interacting system. The proposal focuses specifically on a lattice of coupled Bose-Einstein condensates in the classical regime describable by the discrete Gross-Pitaevskii equation. We suggest to use imperfect time reversal of the system's dynamics known as the Loschmidt echo, which can be realized experimentally by reversing the sign of the Hamiltonian of the system. The routine involves tracking and then subtracting the noise of virtually any observable quantity before and after the time reversal. We support the theoretical analysis by direct numerical simulations demonstrating that the largest Lyapunov exponent can indeed be extracted from the Loschmidt echo routine. We also discuss possible values of experimental parameters required for implementing this proposal.

  3. Using largest Lyapunov exponent to confirm the intrinsic stability of boiling water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Gavilian-Moreno, Carlos [Iberdrola Generacion, S.A., Cofrentes Nuclear Power Plant, Project Engineering Department, Paraje le Plano S/N, Valencia (Spain); Espinosa-Paredes, Gilberto [Area de ingeniera en Recursos Energeticos, Universidad Autonoma Metropolitana-Iztapalapa, Mexico city (Mexico)

    2016-04-15

    The aim of this paper is the study of instability state of boiling water reactors with a method based in largest Lyapunov exponents (LLEs). Detecting the presence of chaos in a dynamical system is an important problem that is solved by measuring the LLE. Lyapunov exponents quantify the exponential divergence of initially close state-space trajectories and estimate the amount of chaos in a system. This method was applied to a set of signals from several nuclear power plant (NPP) reactors under commercial operating conditions that experienced instabilities events, apparently each of a different nature. Laguna Verde and Forsmark NPPs with in-phase instabilities, and Cofrentes NPP with out-of-phases instability. This study presents the results of intrinsic instability in the boiling water reactors of three NPPs. In the analyzed cases the limit cycle was not reached, which implies that the point of equilibrium exerts influence and attraction on system evolution.

  4. Nonuniversality of the Archie exponent due to multifractality of resistivity well logs

    Science.gov (United States)

    Dashtian, Hassan; Yang, Yafan; Sahimi, Muhammad

    2015-12-01

    Archie's law expresses a relation between the formation factor F of porous media and their porosity ϕ, F∝ϕ-m, where m is the Archie or the cementation exponent. Despite widespread use of Archie's law, the value of m and whether it is universal and independent of the type of reservoir have remained controversial. We analyze various porosity and resistivity logs along 36 wells in six Iranian oil and gas reservoirs using wavelet transform coherence and multifractal detrended fluctuation analysis. m is estimated for two sets of data: one set contains the resistivity data that include those segments of the well that contain significant clay content and one without. The analysis indicates that the well logs are multifractal and that due to the multifractality the exponent m is nonuniversal. Thus, analysis of the resistivity of laboratory or outcrop samples that are not multifractal yields estimates of m that are not applicable to well logs in oil or gas reservoirs.

  5. Using Largest Lyapunov Exponent to Confirm the Intrinsic Stability of Boiling Water Reactors

    Directory of Open Access Journals (Sweden)

    Carlos J. Gavilán-Moreno

    2016-04-01

    Full Text Available The aim of this paper is the study of instability state of boiling water reactors with a method based in largest Lyapunov exponents (LLEs. Detecting the presence of chaos in a dynamical system is an important problem that is solved by measuring the LLE. Lyapunov exponents quantify the exponential divergence of initially close state-space trajectories and estimate the amount of chaos in a system. This method was applied to a set of signals from several nuclear power plant (NPP reactors under commercial operating conditions that experienced instabilities events, apparently each of a different nature. Laguna Verde and Forsmark NPPs with in-phase instabilities, and Cofrentes NPP with out-of-phases instability. This study presents the results of intrinsic instability in the boiling water reactors of three NPPs. In the analyzed cases the limit cycle was not reached, which implies that the point of equilibrium exerts influence and attraction on system evolution.

  6. Predicted and verified evolution of power-law exponent in product market

    CERN Document Server

    Hisano, Ryohei; Mizuno, Takayuki

    2011-01-01

    Power-law distributions constitute a generic empirical statistical regularity found in many complex systems. A recently developed theory finds that the interplay between one of the most universal ingredient, i.e., stochastic proportional growth, and stochastic birth and death processes, leads to generic power law distributions together with a non-universal exponent which depends explicitly on the characteristics of growth, birth and death. In particular, the theory rationalizes Zipf's law and explains deviations from it, for instance for the distribution of firm and of city sizes. Here, we report the first complete test of the theory, based on the empirical analysis from a real world complex phenomenon, namely the dynamics of market shares in the consumer electronics market. We estimate directly from the data the average growth rate of market shares, their standard deviation, the birth rates as well as the "death" hazard rate of products. When plugged in the theory, this predicts the power law exponent of the...

  7. Existence of solutions for p-Kirchhoff type problems with critical exponent

    Directory of Open Access Journals (Sweden)

    Ahmed Hamydy

    2011-08-01

    Full Text Available We study the existence of solutions for the p-Kirchhoff type problem involving the critical Sobolev exponent, $$displaylines{ -Big[gBig(int_Omega|abla u|^pdxBigBig]Delta_pu =lambda f(x,u+|u|^{p^star-2}uquadext{in }Omega,cr u=0quadext{on }partialOmega, }$$ where $Omega$ is a bounded smooth domain of $mathbb{R}^N$, $1exponent, $lambda$ is a positive parameter, f and g are continuous functions. The main results of this paper establish, via the variational method. The concentration-compactness principle allows to prove that the Palais-Smale condition is satisfied below a certain level.

  8. Electronic structure, lattice energies and Born exponents for alkali halides from first principles

    Directory of Open Access Journals (Sweden)

    C. R. Gopikrishnan

    2012-03-01

    Full Text Available First principles calculations based on DFT have been performed on crystals of halides (X = F, Cl, Br and I of alkali metals (M = Li, Na, K, Rb and Cs. The calculated lattice energies (U0 are in good agreement with the experimental lattice enthalpies. A new exact formalism is proposed to determine the Born exponent (n for ionic solids. The values of the Born exponent calculated through this ab-initio technique is in good agreement with previous empirically derived results. Band Structure calculations reveal that these compounds are wide-gap insulators that explains their optical transparency. Projected density of states (PDOS calculations reveal that alkali halides with small cations and large anions, have small band gaps due to charge transfer from X → M. This explains the onset of covalency in ionic solids, which is popularly known as the Fajans Rule.

  9. Stability Analysis of Bipedal Robots Using the Concept of Lyapunov Exponents

    Directory of Open Access Journals (Sweden)

    Liu Yunping

    2013-01-01

    Full Text Available The dynamics and stability of passive bipedal robot have an important impact on the mass distribution, leg length, and the angle of inclination. Lyapunov’s second method is difficult to be used in highly nonlinear multibody systems, due to the lack of constructive methods for deriving Lyapunov fuction. The dynamics equation is established by Kane method, the relationship between the mass, length of leg, angle of inclination, and stability of passive bipedal robot by the largest Lyapunov exponent. And the Lyapunov exponents of continuous dynamical systems are estimated by numerical methods, which are simple and easy to be applied to the system stability simulation analysis, provide the design basis for passive bipedal robot prototype, and improve design efficiency.

  10. Lyapunov exponents from kinetic theory for a dilute, field-driven Lorentz gas

    CERN Document Server

    Van Beijeren, H; Cohen, E G D; Posch, H A; Dellago, C

    1996-01-01

    Positive and negative Lyapunov exponents for a dilute, random, two-dimensional Lorentz gas in an applied field, \\vec{E}, in a steady state at constant energy are computed to order E^{2}. The results are: \\lambda_{\\pm}=\\lambda_{\\pm}^{0}-a_{\\pm}(qE/mv)^{2}t_{0} where \\lambda_{\\pm}^{0} are the exponents for the field-free Lorentz gas, a_{+}=11/48, a_{-}=7/48, t_{0} is the mean free time between collisions, q is the charge, m the mass and v is the speed of the particle. The calculation is based on an extended Boltzmann equation in which a radius of curvature, characterizing the separation of two nearby trajectories, is one of the variables in the distribution function. The analytical results are in excellent agreement with computer simulations. These simulations provide additional evidence for logarithmic terms in the density expansion of the diffusion coefficient.

  11. Phase Transitions, Geometrothermodynamics, and Critical Exponents of Black Holes with Conformal Anomaly

    Directory of Open Access Journals (Sweden)

    Jie-Xiong Mo

    2014-01-01

    Full Text Available We investigate the phase transitions of black holes with conformal anomaly in canonical ensemble. Some interesting and novel phase transition phenomena have been discovered. It is shown that there are striking differences in both Hawking temperature and phase structure between black holes with conformal anomaly and those without it. Moreover, we probe in detail the dependence of phase transitions on the choice of parameters. The results show that black holes with conformal anomaly have much richer phase structure than those without it. There would be two, only one, or no phase transition points depending on the parameters. The corresponding parameter regions are derived both numerically and graphically. Geometrothermodynamics are built up to examine the phase structure we have discovered. It is shown that Legendre invariant thermodynamic scalar curvature diverges exactly where the specific heat diverges. Furthermore, critical behaviors are investigated by calculating the relevant critical exponents. And we prove that these critical exponents satisfy the thermodynamic scaling laws.

  12. Dependence of exponents on text length versus finite-size scaling for word-frequency distributions

    Science.gov (United States)

    Corral, Álvaro; Font-Clos, Francesc

    2017-08-01

    Some authors have recently argued that a finite-size scaling law for the text-length dependence of word-frequency distributions cannot be conceptually valid. Here we give solid quantitative evidence for the validity of this scaling law, using both careful statistical tests and analytical arguments based on the generalized central-limit theorem applied to the moments of the distribution (and obtaining a novel derivation of Heaps' law as a by-product). We also find that the picture of word-frequency distributions with power-law exponents that decrease with text length [X. Yan and P. Minnhagen, Physica A 444, 828 (2016), 10.1016/j.physa.2015.10.082] does not stand with rigorous statistical analysis. Instead, we show that the distributions are perfectly described by power-law tails with stable exponents, whose values are close to 2, in agreement with the classical Zipf's law. Some misconceptions about scaling are also clarified.

  13. Common stressful life events and difficulties are associated with mental health symptoms and substance use in young adolescents.

    Science.gov (United States)

    Low, Nancy Cp; Dugas, Erika; O'Loughlin, Erin; Rodriguez, Daniel; Contreras, Gisele; Chaiton, Michael; O'Loughlin, Jennifer

    2012-08-17

    Stressful life events are associated with mood disorders in adults in clinical settings. Less described in the literature is the association between common life stressors and a wide range of psychopathology in young adolescents. This study uses a large non-clinical sample of young adolescents to describe the associations among worry or stress about common life events/difficulties, mental health and substance use. Data on lifetime stress or worry about common life events/difficulties (i.e., romantic breakups, family disruption, interpersonal difficulties, and personal stress (health, weight, school work)), symptoms of depression, conduct disorder symptoms, and substance use were collected from 1025 grade 7 students (mean age 12.9 years; 45% male). The association between each source of stress and each mental health and substance use indicator was modeled in separate logistic regression analyses. The proportion of adolescents reporting worry or stress ranged from 7% for new family to 53% for schoolwork. Romantic breakup stress was statistically significantly associated with all the mental health and substance use indicators except illicit drug use. Family disruption was statistically significantly associated with depression symptoms, marijuana use, and cigarette use. Interpersonal difficulties stress was statistically significantly associated with depression symptoms. All sources of personal stress were statistically significantly related to depression symptoms. In addition, health-related stress was inversely related to binge drinking. Young adolescents may benefit from learning positive coping skills to manage worry or stress about common stressors and in particular, worry or stress related to romantic breakups. Appropriate management of mental health symptoms and substance use related to common stressful life events and difficulties may help reduce emerging psychopathology.

  14. Predictive value of familiality, stressful life events and gender on the course of obsessive-compulsive disorder.

    Science.gov (United States)

    Goldberg, Ximena; Soriano-Mas, Carles; Alonso, Pino; Segalàs, Cinto; Real, Eva; López-Solà, Clara; Subirà, Marta; Via, Esther; Jiménez-Murcia, Susana; Menchón, José M; Cardoner, Narcís

    2015-10-01

    Familiality, stressful life events (SLE) and gender significantly affect the onset of obsessive-compulsive disorder (OCD). However, their combined impact on the probability of OCD chronicity is largely unknown. With the objective of clarifying their predictive value, we tested a model of interaction effects between these influences. A sample of 449 patients with OCD was systematically assessed for familial loading, exposure to stressful life events, gender and course of the disease at the OCD referral unit at Bellvitge University Hospital. Multiple ordinal logistic regression was used to test interaction models. Familiality presented a main negative association with chronicity (OR=0.83, CI97.5%=0.70-0.98). This association was additively moderated by both exposure to SLE before onset and gender, and showed a positive slope among female patients not exposed to SLE before onset (Familiality*SLEbo: OR=0.69, CI97.5%=0.47-1; Familiality*gender: OR=1.30, CI97.5%=0.91-1.84). The findings are based on cross-sectional data. Assessment of course is based on a retrospective measure, which may imply the possibility of overestimation of chronicity. The predictive value of familiality on the course of OCD is only partially informative as both SLEbo and gender modify the association. When other risk factors are included in the model, familiality may predict decreased chances of chronicity. The mediation effects identified could explain the discrepancies found in previous research on this topic. Increased chances of presenting a chronic course of OCD may be found in association with familial vulnerability among female patients not exposed to SLEbo. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Common stressful life events and difficulties are associated with mental health symptoms and substance use in young adolescents

    Directory of Open Access Journals (Sweden)

    Low Nancy CP

    2012-08-01

    Full Text Available Abstract Background Stressful life events are associated with mood disorders in adults in clinical settings. Less described in the literature is the association between common life stressors and a wide range of psychopathology in young adolescents. This study uses a large non-clinical sample of young adolescents to describe the associations among worry or stress about common life events/difficulties, mental health and substance use. Methods Data on lifetime stress or worry about common life events/difficulties (i.e., romantic breakups, family disruption, interpersonal difficulties, and personal stress (health, weight, school work, symptoms of depression, conduct disorder symptoms, and substance use were collected from 1025 grade 7 students (mean age 12.9 years; 45% male. The association between each source of stress and each mental health and substance use indicator was modeled in separate logistic regression analyses. Results The proportion of adolescents reporting worry or stress ranged from 7% for new family to 53% for schoolwork. Romantic breakup stress was statistically significantly associated with all the mental health and substance use indicators except illicit drug use. Family disruption was statistically significantly associated with depression symptoms, marijuana use, and cigarette use. Interpersonal difficulties stress was statistically significantly associated with depression symptoms. All sources of personal stress were statistically significantly related to depression symptoms. In addition, health-related stress was inversely related to binge drinking. Conclusion Young adolescents may benefit from learning positive coping skills to manage worry or stress about common stressors and in particular, worry or stress related to romantic breakups. Appropriate management of mental health symptoms and substance use related to common stressful life events and difficulties may help reduce emerging psychopathology.

  16. Associations among depressive symptoms, childhood abuse, neuroticism, and adult stressful life events in the general adult population

    Directory of Open Access Journals (Sweden)

    Ono K

    2017-02-01

    Full Text Available Kotaro Ono,1 Yoshikazu Takaesu,1 Yukiei Nakai,2 Akiyoshi Shimura,1 Yasuyuki Ono,1 Akiko Murakoshi,1 Yasunori Matsumoto,1 Hajime Tanabe,3 Ichiro Kusumi,2 Takeshi Inoue1 1Department of Psychiatry, Tokyo Medical University, Tokyo, 2Department of Psychiatry, Hokkaido University Graduate School of Medicine, Hokkaido, 3Department of Clinical Human Sciences, Graduate school of Humanities and Social Sciences, Shizuoka University, Shizuoka, Japan Background: Recent studies have suggested that the interactions among several factors affect the onset, progression, and prognosis of major depressive disorder. This study investigated how childhood abuse, neuroticism, and adult stressful life events interact with one another and affect depressive symptoms in the general adult population. Subjects and methods: A total of 413 participants from the nonclinical general adult population completed the Patient Health Questionnaire-9, the Child Abuse and Trauma Scale, the neuroticism subscale of the shortened Eysenck Personality Questionnaire – Revised, and the Life Experiences Survey, which are self-report scales. Structural equation modeling (Mplus version 7.3 and single and multiple regressions were used to analyze the data. Results: Childhood abuse, neuroticism, and negative evaluation of life events increased the severity of the depressive symptoms directly. Childhood abuse also indirectly increased the negative appraisal of life events and the severity of the depressive symptoms through enhanced neuroticism in the structural equation modeling. Limitations: There was recall bias in this study. The causal relationship was not clear because this study was conducted using a cross-sectional design. Conclusion: This study suggested that neuroticism is the mediating factor for the two effects of childhood abuse on adulthood depressive symptoms and negative evaluation of life events. Childhood abuse directly and indirectly predicted the severity of depressive symptoms

  17. Impact of new traumatic or stressful life events on pre-existing PTSD in traumatized refugees: results of a longitudinal study

    Directory of Open Access Journals (Sweden)

    Katrin Schock

    2016-11-01

    Full Text Available Background: A significant proportion of trauma survivors experience an additional critical life event in the aftermath. These renewed experiences of traumatic and stressful life events may lead to an increase in trauma-related mental health symptoms.Method: In a longitudinal study, the effects of renewed experiences of a trauma or stressful life event were examined. For this purpose, refugees seeking asylum in Germany were assessed for posttraumatic stress symptoms (PTS, Posttraumatic Stress Diagnostic Scale (PDS, anxiety, and depression (Hopkins Symptom Checklist [HSCL-25] before treatment start as well as after 6 and 12 months during treatment (N=46. Stressful life events and traumatic events were recorded monthly. If a new event happened, PDS and HSCL were additionally assessed directly afterwards. Mann–Whitney U-tests were performed to calculate the differences between the group that experienced an additional critical event (stressful vs. trauma during treatment (n=23 and the group that did not (n=23, as well as differences within the critical event group between the stressful life event group (n=13 and the trauma group (n=10.Results: Refugees improved significantly during the 12-month period of our study, but remained severely distressed. In a comparison of refugees with a new stressful life event or trauma, significant increases in PTS, anxiety, and depressive symptoms were found directly after the experience, compared to the group without a renewed event during the 12 months of treatment. With regard to the different critical life events (stressful vs. trauma, no significant differences were found regarding overall PTS, anxiety, and depression symptoms. Only avoidance symptoms increased significantly in the group experiencing a stressful life event.Conclusion: Although all clinicians should be aware of possible PTS symptom reactivation, especially those working with refugees and asylum seekers, who often experience new critical life

  18. The interplay of stressful life events and coping skills on risk for suicidal behavior among youth students in contemporary China: a large scale cross-sectional study.

    Science.gov (United States)

    Tang, Fang; Xue, Fuzhong; Qin, Ping

    2015-07-31

    Stressful life events are common among youth students and may induce psychological problems and even suicidal behaviors in those with poor coping skills. This study aims to assess the influence of stressful life events and coping skills on risk for suicidal behavior and to elucidate the underlying mechanism using a large sample of university students in China. 5972 students, randomly selected from 6 universities, completed the questionnaire survey. Logistic regression analysis was performed to estimate the effect of stressful life events and coping skills on risk for suicidal behavior. Bayesian network was further adopted to probe their probabilistic relationships. Of the 5972 students, 7.64% reported the presence of suicidal behavior (attempt or ideation) within the past one year period. Stressful life events such as strong conflicts with classmates and a failure in study exam constituted strong risk factors for suicidal behavior. The influence of coping skills varied according to the strategies adapted toward problems with a high score of approach coping skills significantly associated with a reduced risk of suicidal behavior. The Bayesian network indicated that the probability of suicidal behavior associated with specific life events was to a large extent conditional on coping skills. For instance, a stressful experience of having strong conflicts with classmates could result in a probability of suicidal behavior of 21.25% and 15.36% respectively, for female and male students with the score of approach coping skills under the average. Stressful life events and deficient coping skills are strong risk factors for suicidal behavior among youth students. The results underscore the importance of prevention efforts to improve coping skills towards stressful life events.

  19. Proposing a normalized Biot number: For simpler determination of Fourier exponents and for evaluating the sensitivity of the Biot number

    DEFF Research Database (Denmark)

    Christensen, Martin Gram; Adler-Nissen, Jens

    2015-01-01

    This paper presents a normalization of the Biot number, which enables the Fourier exponents to be fitted with a simple 3rd order polynomial (R2 > 0.9999). The method is validated for Biot numbers ranging from 0.02 to 8, and presented graphically for both the Fourier exponents and the lag factors ...... needed in the series expansion. The lag factors and Fourier exponents are validated with an average variation coefficient (CVRMSD) less than 0.006. The resulting prediction error of the thermal response is ...This paper presents a normalization of the Biot number, which enables the Fourier exponents to be fitted with a simple 3rd order polynomial (R2 > 0.9999). The method is validated for Biot numbers ranging from 0.02 to 8, and presented graphically for both the Fourier exponents and the lag factors...

  20. Estimation of time-dependent Hurst exponents with variational smoothing and application to forecasting foreign exchange rates

    Science.gov (United States)

    Garcin, Matthieu

    2017-10-01

    Hurst exponents depict the long memory of a time series. For human-dependent phenomena, as in finance, this feature may vary in the time. It justifies modelling dynamics by multifractional Brownian motions, which are consistent with time-dependent Hurst exponents. We improve the existing literature on estimating time-dependent Hurst exponents by proposing a smooth estimate obtained by variational calculus. This method is very general and not restricted to the sole Hurst framework. It is globally more accurate and easier than other existing non-parametric estimation techniques. Besides, in the field of Hurst exponents, it makes it possible to make forecasts based on the estimated multifractional Brownian motion. The application to high-frequency foreign exchange markets (GBP, CHF, SEK, USD, CAD, AUD, JPY, CNY and SGD, all against EUR) shows significantly good forecasts. When the Hurst exponent is higher than 0.5, what depicts a long-memory feature, the accuracy is higher.

  1. Effective Power-Law Dependence of Lyapunov Exponents on the Central Mass in Galaxies

    Science.gov (United States)

    Delis, N.; Efthymiopoulos, C.; Kalapotharakos, C.

    2015-01-01

    Using both numerical and analytical approaches, we demonstrate the existence of an effective power-law relation L alpha m(sup p) between themean Lyapunov exponent L of stellar orbits chaotically scattered by a supermassive black hole (BH) in the centre of a galaxy and the mass parameter m, i.e. ratio of the mass of the BH over the mass of the galaxy. The exponent p is found numerically to obtain values in the range p approximately equals 0.3-0.5. We propose a theoretical interpretation of these exponents, based on estimates of local 'stretching numbers', i.e. local Lyapunov exponents at successive transits of the orbits through the BH's sphere of influence. We thus predict p = 2/3 - q with q approximately equaling 0.1-0.2. Our basic model refers to elliptical galaxy models with a central core. However, we find numerically that an effective power-law scaling of L with m holds also in models with central cusp, beyond a mass scale up to which chaos is dominated by the influence of the cusp itself. We finally show numerically that an analogous law exists also in disc galaxies with rotating bars. In the latter case, chaotic scattering by the BH affects mainly populations of thick tube-like orbits surrounding some low-order branches of the x(sub 1) family of periodic orbits, as well as its bifurcations at low-order resonances, mainly the inner Lindblad resonance and the 4/1 resonance. Implications of the correlations between L and m to determining the rate of secular evolution of galaxies are discussed.

  2. Perturbation theory for Lyapunov exponents of an Anderson model on a strip

    CERN Document Server

    Schulz-Baldes, H

    2003-01-01

    It is proven that the localization length of an Anderson model on a strip of width $L$ is bounded above by $L/\\lambda^2$ for small values of the coupling constant $\\lambda$ of the disordered potential. For this purpose, a new formalism is developed in order to calculate the bottom Lyapunov exponent associated with random products of large symplectic matrices perturbatively in the coupling constant of the randomness.

  3. Critical exponents in the transition to chaos in one-dimensional ...

    Indian Academy of Sciences (India)

    obey the relation λ. µ µ∞ ν. (1) where µ∞ is the value of the control parameter µ at the Feigenbaum point or accumulation point of period doubling transitions andν is the associated critical exponent. In the context of unimodal maps like the logistic map,ν is given by the Huberman–Rudnick (HR) relation ν(z) = ln 2 ln δ(z). (2).

  4. The exponent λ (x,Q ) of the proton structure function F (x, Q ) at low ...

    Indian Academy of Sciences (India)

    Abstract. The exponent λ of the structure function F2 x λ is calculated using the solution of the DGLAP equation for gluon at low x reported recently by the present authors. The quantity λ is calculated both as a function of x at fixed Q2 and as a function of Q2 at fixed x and compared with the most recent data from H1.

  5. Short Zero-Sum Sequences Over Abelian $p$-Groups of Large Exponent

    OpenAIRE

    Luo, Sammy

    2016-01-01

    Let $G$ be a finite abelian group with exponent $n$. Let $\\eta(G)$ denote the smallest integer $\\ell$ such that every sequence over $G$ of length at least $\\ell$ has a zero-sum subsequence of length at most $n$. We determine the precise value of $\\eta(G)$ when $G$ is a $p$-group whose Davenport constant is at most $2n-1$. This confirms one of the equalities in a conjecture by Schmid and Zhuang from 2010.

  6. A Lower Bound on the Lyapunov Exponent for the Generalized Harper's Model

    Science.gov (United States)

    Jitomirskaya, Svetlana; Liu, Wencai

    2017-02-01

    We obtain a lower bound for the Lyapunov exponent of a family of discrete Schrödinger operators (Hu)_n=u_{n+1}+u_{n-1}+2a_1 cos 2π (θ +nα )u_n+2a_2 cos 4π (θ +nα )u_n, that incorporates both a_1 and a_2, thus going beyond the Herman's bound.

  7. Gender differences in stressful life events, social support, perceived stress, and alcohol use among older adults: results from a National Survey.

    Science.gov (United States)

    Sacco, Paul; Bucholz, Kathleen K; Harrington, Donna

    2014-03-01

    Stressful life events, perceived stress, and social support relationships with consumption, at-risk drinking, and alcohol use disorder (AUD) were studied in a population-based sample of current drinkers age 60+ in the National Epidemiologic Survey of Alcohol and Related Conditions (Wave 2; 2004-2005; n = 4,360). Stressful life events were associated with AUD among men and women, and crime victimization among men only. However, greater perceived stress was associated with lower consumption among women and greater odds of AUD in men, highlighting differences in the relationship between stress and alcohol use by gender that may be the result of the stress alcohol link.

  8. Scaling exponent and dispersity of polymers in solution by diffusion NMR.

    Science.gov (United States)

    Williamson, Nathan H; Röding, Magnus; Miklavcic, Stanley J; Nydén, Magnus

    2017-05-01

    Molecular mass distribution measurements by pulsed gradient spin echo nuclear magnetic resonance (PGSE NMR) spectroscopy currently require prior knowledge of scaling parameters to convert from polymer self-diffusion coefficient to molecular mass. Reversing the problem, we utilize the scaling relation as prior knowledge to uncover the scaling exponent from within the PGSE data. Thus, the scaling exponent-a measure of polymer conformation and solvent quality-and the dispersity (Mw/Mn) are obtainable from one simple PGSE experiment. The method utilizes constraints and parametric distribution models in a two-step fitting routine involving first the mass-weighted signal and second the number-weighted signal. The method is developed using lognormal and gamma distribution models and tested on experimental PGSE attenuation of the terminal methylene signal and on the sum of all methylene signals of polyethylene glycol in D2O. Scaling exponent and dispersity estimates agree with known values in the majority of instances, leading to the potential application of the method to polymers for which characterization is not possible with alternative techniques. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Fitting Power-laws in empirical data with estimators that work for all exponents

    CERN Document Server

    Hanel, Rudolf; Liu, Bo; Thurner, Stefan

    2016-01-01

    It has been repeatedly stated that maximum likelihood (ML) estimates of exponents of power-law distributions can only be reliably obtained for exponents smaller than minus one. The main argument that power laws are otherwise not normalizable, depends on the underlying sample space the data is drawn from, and is true only for sample spaces that are unbounded from above. Here we show that power-laws obtained from bounded sample spaces (as is the case for practically all data related problems) are always free of such limitations and maximum likelihood estimates can be obtained for arbitrary powers without restrictions. Here we first derive the appropriate ML estimator for arbitrary exponents of power-law distributions on bounded discrete sample spaces. We then show that an almost identical estimator also works perfectly for continuous data. We implemented this ML estimator and discuss its performance with previous attempts. We present a general recipe of how to use these estimators and present the associated com...

  10. Serotonin Transporter-Linked Polymorphic Region (5-HTTLPR) Genotype and Stressful Life Events Interact to Predict Preschool-Onset Depression: A Replication and Developmental Extension

    Science.gov (United States)

    Bogdan, Ryan; Agrawal, Arpana; Gaffrey, Michael S.; Tillman, Rebecca; Luby, Joan L.

    2014-01-01

    Background: Scientific enthusiasm about gene × environment interactions, spurred by the 5-HTTLPR (serotonin transporter-linked polymorphic region) × SLEs (stressful life events) interaction predicting depression, have recently been tempered by sober realizations of small effects and meta-analyses reaching opposing conclusions. These mixed findings…

  11. Coexisting Psychiatric Problems and Stressful Life Events in Adults with Symptoms of ADHD--A Large Swedish Population-Based Study of Twins

    Science.gov (United States)

    Friedrichs, Bettina; Igl, Wilmar; Larsson, Henrik; Larsson, Jan-Olov

    2012-01-01

    Objective: To explore the associations of subtypes of adult ADHD with other psychiatric problems, stressful life events, and sex differences. Method: Odds ratios were calculated using information from 17,899 participants from a population-based survey of adult twins born in Sweden between 1959 and 1985. Results: Symptoms of attention deficit…

  12. Role of Stressful Life Events, Avoidant Coping Styles, and Neuroticism in Online Game Addiction among College Students: A Moderated Mediation Model.

    Science.gov (United States)

    Li, Huanhuan; Zou, Yingmin; Wang, Jiaqi; Yang, Xuelin

    2016-01-01

    Online game addiction (OGA) is becoming a significant problem worldwide. The aim of this study was to explore the incidence of OGA and the roles of stressful life events, avoidant coping styles (ACSs), and neuroticism in OGA. A total of 651 Chinese college students were selected by random cluster sampling. Subjects completed the Chinese version of Young's eight-item Internet Addiction Scale (CIAS), Online Game Cognition Addiction Scale (OGCAS), Revised Eysenck Personality Questionnaire Short Scale in Chinese (EPQ-RSC), Chinese College-student Stress Questionnaire, and Coping Style Questionnaire. Structural equation modeling (SEM) was used to explore the interactive effects of stressful life events, ACSs, and neuroticism on OGA. Of the 651 participants in the sample, 31 (4.8%) were identified as addicts. The incidence of OGA was two times higher for males than females. The addicts had markedly higher scores on the neuroticism subscale of the EPQ-RSC than non-addicts. Compared to non-addicts, addicts were more apt to use ACSs. Having an avoidant coping strategy mediated the effect of stressful life events on OGA. Furthermore, neuroticism moderated the indirect effect of stressful life events on OGA via ACSs. Applications of these findings to etiological research and clinical treatment programs are discussed.

  13. Gender Differences in Depressive Symptoms during Adolescence: Role of Gender-Typed Characteristics, Self-Esteem, Body Image, Stressful Life Events, and Pubertal Status.

    Science.gov (United States)

    Marcotte, Diane; Fortin, Laurier; Potvin, Pierre; Papillon, Myra

    2002-01-01

    In a study of French-speaking adolescents (n=547), five measures designed to examine psychological well being found that body image, self-esteem, and negative stressful life events mediate the relationship between gender and depressive symptoms during adolescence. Further analysis of a subsample who recently transitioned to high school also found…

  14. The Effects of Depression and Stressful Life Events on the Development and Maintenance of Syndromal Social Anxiety: Sex and Age Differences

    Science.gov (United States)

    Aune, Tore; Stiles, Tore C.

    2009-01-01

    This study assessed age and sex differences in the prevalence and incidence rates of syndromal social anxiety (SSA), as well as the predictive role of depressive symptoms and stressful life events on the development and persistence of SSA. A sample of 1,439 young people, between 11 and 14 years of age, was assessed twice within a 12-month…

  15. Investigating the interactive role of stressful life events, reinforcement sensitivity and personality traits in prediction of the severity of Multiple Sclerosis (MS symptoms

    Directory of Open Access Journals (Sweden)

    2017-06-01

    Full Text Available Background & Objective: Multiple sclerosis is a chronic neurological condition recognized by demyelination in the central nervous system. The present study was conducted to investigate the interactive role of stressful life events, reinforcement sensitivity, and personality traits in prediction of the severity of symptoms of Multiple sclerosis (MS symptoms. Materials & Methods: This is a correlational study whose statistical population consisted of all the patients suffering from Multiple Sclerosis in Shiraz in the first half of 1394, among whom 162 patients were included in this research by means of purposive sampling method. Five-Factor Personality Inventory, Jackson Personality Inventory, Stressful Life Events Scale, and Expanded Disability Status Scale (EDSS were utilised as research tools. In order to analyze the data, descriptive and inferential methods were used. The data were analysed using Pearson correlation and hierarchical regression. Results: The findings revealed that stressful life events (β = 0.41, p <0.001, Behavioral Inhibition System (β = 0.26, p<0.05, and neuroticism index (β = 0.92, p <0.05 were able to predict variance of scores of the severity of symptoms of Multiple Sclerosis significantly. Conclusion: Stressful life events, Behavioral Inhibition System, and neuroticism showed a significant relationship with the severity of symptoms of Multiple Sclerosis; thus, it seems that interaction of personality traits and environmental conditions are among influential factors of the severity of symptoms of Multiple Sclerosis. This fact implies that individuals' personal traits play an eminent role in the progression of the disease.

  16. A Survey on the Generalized Problematic Internet Use in Chinese College Students and Its Relations to Stressful Life Events and Coping Style

    Science.gov (United States)

    Li, Huanhuan; Wang, Jiaqi; Wang, Li

    2009-01-01

    Problematic internet use (PIU) during the college life becomes a significant public health concern with a variety of negative outcomes. The aim of the present study was to examine the incidence of generalized PIU (GPIU) and its relationship to stressful life events and coping style among Chinese college students. Six hundred and fifty-four college…

  17. Role of stressful life events, avoidant coping styles, and neuroticism in online game addiction among college students: a moderated mediation model

    Directory of Open Access Journals (Sweden)

    Li Huanhuan

    2016-11-01

    Full Text Available Online game addiction (OGA is becoming a significant problem worldwide. The aim of this study was to explore the incidence of OGA and the roles of stressful life events, avoidant coping styles (ACSs, and neuroticism in OGA. A total of 651 Chinese college students were selected by random cluster sampling. Subjects completed the Chinese version of Young’s eight-item Internet Addiction Scale (CIAS, Online Game Cognition Addiction Scale (OGCAS, Revised Eysenck Personality Questionnaire Short Scale in Chinese (EPQ-RSC, Chinese College-student Stress Questionnaire (CCSQ, and Coping Style Questionnaire (CSQ. Structural equation modeling (SEM was used to explore the interactive effects of stressful life events, ACSs, and neuroticism on OGA. Of the 651 participants in the sample, 31 (4.8% were identified as addicts. The incidence of OGA was two times higher for males than females. The addicts had markedly higher scores on the neuroticism subscale of the EPQ-RSC than non-addicts. Compared to non-addicts, addicts were more apt to use ACSs. Having an avoidant coping strategy mediated the effect of stressful life events on OGA. Furthermore, neuroticism moderated the indirect effect of stressful life events on OGA via ACSs. Applications of these findings to etiological research and clinical treatment programs are discussed.

  18. The impact of stressful life events on excessive alcohol consumption in the French population: findings from the GAZEL cohort study.

    Directory of Open Access Journals (Sweden)

    Sara L Tamers

    Full Text Available Major life changes may play a causative role in health through lifestyle factors, such as alcohol. The objective was to examine the impact of stressful life events on heavy alcohol consumption among French adults.Trajectories of excessive alcohol consumption in 20,625 employees of the French national gas and electricity company for up to 5 years before and 5 years after an event, with annual measurements from 1992. We used repeated measures analysis of time series data indexed to events, employing generalized estimating equations.For women, excessive alcohol use increased before important purchase (p = 0.021, children leaving home (p<0.001, and death of loved ones (p = 0.03, and decreased before widowhood (p = 0.015; in the year straddling the event, increased consumption was observed for important purchase (p = 0.018 and retirement (p = 0.002; at the time of the event, consumption decreased for marriage (p = 0.002, divorce, widowhood, and death of loved one (all p<0.001, and increased for retirement (p = 0.035. For men, heavy alcohol consumption increased in the years up to and surrounding the death of loved ones, retirement, and important purchase (all p<0.001, and decreased after (all p<0.001, except death of loved one: p = 0.006; at the time of the event, consumption decreased for all events except for children leaving home and retirement, where we observed an increase (all p<0.001. For women and men, heavy alcohol consumption decreased prior to marriage and divorce and increased after (all p<0.001, except for women and marriage: p = 0.01.Stressful life events promote healthy and unhealthy alcohol consumption. Certain events impact alcohol intake temporarily while others have longer-term implications. Research should disentangle women's and men's distinct perceptions of events over time.

  19. Rumination as a mechanism linking stressful life events to symptoms of depression and anxiety: longitudinal evidence in early adolescents and adults.

    Science.gov (United States)

    Michl, Louisa C; McLaughlin, Katie A; Shepherd, Kathrine; Nolen-Hoeksema, Susan

    2013-05-01

    Rumination is a well-established risk factor for the onset of major depression and anxiety symptomatology in both adolescents and adults. Despite the robust associations between rumination and internalizing psychopathology, there is a dearth of research examining factors that might lead to a ruminative response style. In the current study, we examined whether social environmental experiences were associated with rumination. Specifically, we evaluated whether self-reported exposure to stressful life events predicted subsequent increases in rumination. We also investigated whether rumination served as a mechanism underlying the longitudinal association between self-reported stressful life events and internalizing symptoms. Self-reported stressful life events, rumination, and symptoms of depression and anxiety were assessed in 2 separate longitudinal samples. A sample of early adolescents (N = 1,065) was assessed at 3 time points spanning 7 months. A sample of adults (N = 1,132) was assessed at 2 time points spanning 12 months. In both samples, self-reported exposure to stressful life events was associated longitudinally with increased engagement in rumination. In addition, rumination mediated the longitudinal relationship between self-reported stressors and symptoms of anxiety in both samples and the relationship between self-reported life events and symptoms of depression in the adult sample. Identifying the psychological and neurobiological mechanisms that explain a greater propensity for rumination following stressors remains an important goal for future research. This study provides novel evidence for the role of stressful life events in shaping characteristic responses to distress, specifically engagement in rumination, highlighting potentially useful targets for interventions aimed at preventing the onset of depression and anxiety. © 2013 American Psychological Association

  20. Signal preserving and seismic random noise attenuation by Hurst exponent based time-frequency peak filtering

    Science.gov (United States)

    Zhang, Chao; Li, Yue; Lin, Hongbo; Yang, Baojun

    2015-11-01

    Attenuating random noise is of great significance in seismic data processing. In recent years, time-frequency peak filtering (TFPF) has been successfully applied to seismic random noise attenuation field. However, a fixed window length (WL) is used in the conventional TFPF. Since a short WL in the TFPF is used to preserve signals while a long WL can eliminate random noise effectively, signal preserving and noise attenuation cannot be balanced by a fixed WL especially when the signal-to-noise ratio of the noisy seismic record is low. Thus, we need to divide a noisy signal into signal and noise segments before the filtering. Then a short WL is used to the signal segments to preserve signals and a long WL is chosen for noise segments to eliminate random noise. In this paper, we test the smoothness of signals and random noise in time using the Hurst exponent which is a statistic for representing smoothness characteristics of signals. The time-series of signals with higher smoothness which lead to larger Hurst exponent values, however random noise is a random series in time without fixed waveforms and thus its smoothness is low, so the signal and noise segments can be divided by the Hurst exponent values. After the segmentation, we can adopt different filtering WLs in the TFPF for different segments to make a trade-off between signal preserving and random noise attenuation. Synthetic and real data experiments demonstrate that the proposed method can remove random noise from seismic record and preserve reflection events effectively.

  1. Lagrangian coherent structures and the smallest finite-time Lyapunov exponent

    Science.gov (United States)

    Haller, George; Sapsis, Themistoklis

    2011-06-01

    We point out that local minimizing curves, or troughs, of the smallest finite-time Lyapunov exponent (FTLE) field computed over a time interval [t0, t] and graphed over trajectory positions at time t mark attracting Lagrangian coherent structures (LCSs) at t. For two-dimensional area-preserving flows, we conclude that computing the largest forward-time FTLE field by itself is sufficient for locating both repelling LCSs at t0 and attracting LCSs at t. We illustrate our results on analytic examples, as well as on a two-dimensional experimental velocity field measured near a swimming jellyfish.

  2. Determination of the interfacial roughness exponent in rare-earth superlattices

    DEFF Research Database (Denmark)

    Swaddling, P.P.; McMorrow, D.F.; Cowley, R.A.

    1994-01-01

    The interfacial roughness in Ho/Y and Ho/Lu superlattices has been studied using high-resolution x-ray diffraction. The transverse width of the superlattice Bragg peaks broadens almost linearly as a function of the component of the reduced wave vector parallel to the growth direction, while...... the line shape is invariant, and is described by a Lorentzian raised to the power of approximate to 5/2. These results are interpreted as a signature of conformally rough interfaces, and the roughness exponent is determined to be alpha = 0.85 +/- 0.05. It is also shown how alpha may be altered by adjusting...

  3. Estimation of Spectral Exponent Parameter of 1/f Process in Additive White Background Noise

    Directory of Open Access Journals (Sweden)

    Semih Ergintav

    2007-01-01

    Full Text Available An extension to the wavelet-based method for the estimation of the spectral exponent, γ, in a 1/fγ process and in the presence of additive white noise is proposed. The approach is based on eliminating the effect of white noise by a simple difference operation constructed on the wavelet spectrum. The γ parameter is estimated as the slope of a linear function. It is shown by simulations that the proposed method gives reliable results. Global positioning system (GPS time-series noise is analyzed and the results provide experimental verification of the proposed method.

  4. Estimating the density-scaling exponent of a monatomic liquid from its pair potential

    DEFF Research Database (Denmark)

    Bøhling, Lasse; Bailey, Nicholas; Schrøder, Thomas

    2014-01-01

    This paper investigates two conjectures for calculating the density dependence of the density-scaling exponent γ of a single-component, pair-potential liquid with strong virial potential-energy correlations. The first conjecture gives an analytical expression for γ directly in terms of the pair...... potential. The second conjecture is a refined version of this involving the most likely nearest-neighbor distance determined from the pair-correlation function. The conjectures are tested by simulations of three systems, one of which is the standard Lennard-Jones liquid. While both expressions give...

  5. Implications of Grain Size Evolution for the Effective Stress Exponent in Ice

    Science.gov (United States)

    Behn, M. D.; Goldsby, D. L.; Hirth, G.

    2016-12-01

    Viscous flow in ice has typically been described by the Glen law—a non-Newtonian, power-law relationship between stress and strain-rate with a stress exponent n 3. The Glen law is attributed to grain-size-insensitive dislocation creep; however, laboratory and field studies demonstrate that deformation in ice is strongly dependent on grain size. This has led to the hypothesis that at sufficiently low stresses, ice flow is controlled by grain boundary sliding [1], which explicitly incorporates the grain-size dependence of ice rheology. Yet, neither dislocation creep (n 4), nor grain boundary sliding (n 1.8), have stress exponents that match the value of n 3 for the Glen law. Thus, although the Glen law provides an approximate description of ice flow in glaciers and ice sheets, its functional form cannot be explained by a single deformation mechanism. Here we seek to understand the origin of the n 3 dependence of the Glen law through a new model for grain-size evolution in ice. In our model, grain size evolves in response to the balance between dynamic recrystallization and grain growth. To simulate these processes we adapt the "wattmeter" [2], originally developed within the solid-Earth community to quantify grain size in crustal and mantle rocks. The wattmeter posits that grain size is controlled by a balance between the mechanical work required for grain growth and dynamic grain size reduction. The evolution of grain size in turn controls the relative contributions of dislocation creep and grain boundary sliding, and thus the effective stress exponent for ice flow. Using this approach, we first benchmark our grain size evolution model on experimental data and then calculate grain size in two end-member scenarios: (1) as a function of depth within an ice-sheet, and (2) across an ice-stream margin. We show that the calculated grain sizes match ice core observations for the interior of ice sheets. Furthermore, owing to the influence of grain size on strain rate, the

  6. Fractal dimensions of graph of Weierstrass-type function and local Hölder exponent spectra

    Science.gov (United States)

    Otani, Atsuya

    2018-01-01

    We study several fractal properties of the Weierstrass-type function where τ :[0, 1)\\to[0, 1) is a cookie cutter map with possibly fractal repeller, and λ and g are functions with proper regularity. In the first part, we determine the box dimension of the graph of W and Hausdorff dimension of its randomised version. In the second part, the Hausdorff spectrum of the local Hölder exponent is characterised in terms of thermodynamic formalism. Furthermore, in the randomised case, a novel formula for the lifted Hausdorff spectrum on the graph is provided.

  7. Control of chaos in permanent magnet synchronous motor by using optimal Lyapunov exponents placement

    Energy Technology Data Exchange (ETDEWEB)

    Ataei, Mohammad, E-mail: ataei@eng.ui.ac.i [Department of Electrical Engineering, Faculty of Engineering, University of Isfahan, Hezar-Jerib St., Postal Code 8174673441, Isfahan (Iran, Islamic Republic of); Kiyoumarsi, Arash, E-mail: kiyoumarsi@eng.ui.ac.i [Department of Electrical Engineering, Faculty of Engineering, University of Isfahan, Hezar-Jerib St., Postal Code 8174673441, Isfahan (Iran, Islamic Republic of); Ghorbani, Behzad, E-mail: behzad.ghorbani63@gmail.co [Department of Control Engineering, Najafabad Azad University, Najafabad, Isfahan (Iran, Islamic Republic of)

    2010-09-13

    Permanent Magnet Synchronous Motor (PMSM) experiences chaotic behavior for a certain range of its parameters. In this case, since the performance of the PMSM degrades, the chaos should be eliminated. In this Letter, the control of the undesirable chaos in PMSM using Lyapunov exponents (LEs) placement is proposed that is also improved by choosing optimal locations of the LEs in the sense of predefined cost function. Moreover, in order to provide the physical realization of the method, nonlinear parameter estimator for the system is suggested. Finally, to show the effectiveness of the proposed methodology, the simulation results for applying this control strategy are provided.

  8. The Use of the Lexical Exponents of Hypothetical Modality in Polish and Lithuanian

    Directory of Open Access Journals (Sweden)

    Danuta Roszko

    2016-12-01

    Full Text Available The Use of the Lexical Exponents of Hypothetical Modality in Polish and Lithuanian In this article the author focuses on the issue of hypothetical modality[1] in Polish and Lithuanian. A list of the basic exponents of hypothetical modality in both languages is presented. However, the focus is mainly placed on the lexical exponents. On the basis of one of the six groups, which describes a high degree of probability (H5, the differences between the use of the lexical exponents in both languages are examined. In the study, multilingual corpora resources, including The Polish-Lithuanian parallel corpus Clarin-PL., are utilized. [1] [In the academic literature, for the notion described herein, the term of epistemic modality is also used.  Nevertheless, in this paper I will continue to use the term of hypotheticality, which I borrowed from the studies on modality, conducted in Polish-Bulgarian cooperation (Slavic Institute of Polish Academy of Sciences and Institute for Bulgarian Language of the Bulgarian Academy of Sciences.]   O użyciu wykładników leksykalnych modalności hipotetycznej w językach polskim i litewskim W artykule autorka porusza zagadnienie modalności hipotetycznej[1]  w językach polskim i litewskim. Przedstawia wykaz podstawowych wykładników modalności hipotetycznej w obu językach. Główną uwagę skupia jednak na wykładnikach leksykalnych. Na przykładzie jednej z sześciu grup, opisującej wysoki stopień prawdopodobieństwa (H5, omawia różnice użycia wykładników leksykalnych w obu językach. W badaniach wykorzystuje wielojęzyczne zasoby korpusowe, w tym Polsko-litewski korpus równoległy Clarin-PL. [1] [W literaturze przedmiotu na oznaczenie opisywanych tu treści stosowany jest również termin epistemiczności. Niemniej jednak w tej pracy autorka pozostaje przy terminie hipotetyczności, który zapożycza z badań nad modalnością, prowadzonych we współpracy polsko-bułgarskiej (Instytut Slawistyki PAN i

  9. Probability density and scaling exponents of longitudinal structure functions in strong turbulence

    CERN Document Server

    Yakhot, V

    1997-01-01

    The advective terms in the Navier-Stokes and Burgers equations are similar. It is proposed that the longitudinal structure functions $S_{n}(r)$ in homogeneous and isotropic three- dimensional turbulence are goverened by a one-dimensional equation of motion, resembling the 1D-Burgers equation, with the strongly non-local pressure contributions accounted for by galilean-invariance-breaking terms. The resulting equations give both scaling exponents and amplitudes of the structure functions in an excellent agreement with experimental data. The derived probability density function $P(\\Delta u,r)\

  10. Some comments on Hurst exponent and the long memory processes on capital markets

    Science.gov (United States)

    Sánchez Granero, M. A.; Trinidad Segovia, J. E.; García Pérez, J.

    2008-09-01

    The analysis of long memory processes in capital markets has been one of the topics in finance, since the existence of the market memory could implicate the rejection of an efficient market hypothesis. The study of these processes in finance is realized through Hurst exponent and the most classical method applied is R/S analysis. In this paper we will discuss the efficiency of this methodology as well as some of its more important modifications to detect the long memory. We also propose the application of a classical geometrical method with short modifications and we compare both approaches.

  11. Extracting the scaling exponents of a self-affine, non-Gaussian process from a finite-length time series

    Science.gov (United States)

    Kiyani, K.; Chapman, S. C.; Hnat, B.

    2006-11-01

    We address the generic problem of extracting the scaling exponents of a stationary, self-affine process realized by a time series of finite length, where information about the process is not known a priori. Estimating the scaling exponents relies upon estimating the moments, or more typically structure functions, of the probability density of the differenced time series. If the probability density is heavy tailed, outliers strongly influence the scaling behavior of the moments. From an operational point of view, we wish to recover the scaling exponents of the underlying process by excluding a minimal population of these outliers. We test these ideas on a synthetically generated symmetric α -stable Lévy process and show that the Lévy exponent is recovered in up to the 6th order moment after only ˜0.1-0.5% of the data are excluded. The scaling properties of the excluded outliers can then be tested to provide additional information about the system.

  12. Associations among depressive symptoms, childhood abuse, neuroticism, and adult stressful life events in the general adult population

    Science.gov (United States)

    Ono, Kotaro; Takaesu, Yoshikazu; Nakai, Yukiei; Shimura, Akiyoshi; Ono, Yasuyuki; Murakoshi, Akiko; Matsumoto, Yasunori; Tanabe, Hajime; Kusumi, Ichiro; Inoue, Takeshi

    2017-01-01

    Background Recent studies have suggested that the interactions among several factors affect the onset, progression, and prognosis of major depressive disorder. This study investigated how childhood abuse, neuroticism, and adult stressful life events interact with one another and affect depressive symptoms in the general adult population. Subjects and methods A total of 413 participants from the nonclinical general adult population completed the Patient Health Questionnaire-9, the Child Abuse and Trauma Scale, the neuroticism subscale of the shortened Eysenck Personality Questionnaire – Revised, and the Life Experiences Survey, which are self-report scales. Structural equation modeling (Mplus version 7.3) and single and multiple regressions were used to analyze the data. Results Childhood abuse, neuroticism, and negative evaluation of life events increased the severity of the depressive symptoms directly. Childhood abuse also indirectly increased the negative appraisal of life events and the severity of the depressive symptoms through enhanced neuroticism in the structural equation modeling. Limitations There was recall bias in this study. The causal relationship was not clear because this study was conducted using a cross-sectional design. Conclusion This study suggested that neuroticism is the mediating factor for the two effects of childhood abuse on adulthood depressive symptoms and negative evaluation of life events. Childhood abuse directly and indirectly predicted the severity of depressive symptoms. PMID:28243100

  13. Association of family stressful life-change events and health-related quality of life in fifth-grade children.

    Science.gov (United States)

    Coker, Tumaini R; Elliott, Marc N; Wallander, Jan L; Cuccaro, Paula; Grunbaum, Jo Anne; Corona, Rosalie; Saunders, Ann E; Schuster, Mark A

    2011-04-01

    To examine the association of recent family-related stressful life-change events (SLEs) with health-related quality of life (HRQOL) in fifth graders. Population-based, cross-sectional survey. Three US metropolitan areas; 2004-2006. A total of 5147 fifth graders and their parents. Nine recent family-related SLEs: a parent's death, another family member's death, a family member's injury/illness, a family member's alcohol/drug problems, loss of a pet, recent change of residence, addition of a new baby or child to the household, parental separation, and parental divorce. The HRQOL measured using the 23-item Pediatric Quality of Life Inventory. Twenty-four percent of children had no reported recent SLEs; 33% had 1, 25% had 2, 12% had 3, and 6% had 4 or more. Mean HRQOL scores (total, physical, and psychosocial scales) were lower for children with more SLEs. The mean total HRQOL score was 80.4 (95% confidence interval, 79.4-81.3) for children with no recent SLEs and 71.8 (70.2-73.5) for children with 4 or more SLEs (P positive HRQOL. By incorporating the needs of families as part of comprehensive, high-quality care, health care professionals can identify these types of family-level needs and assist families in accessing community resources for support.

  14. Couple adjustment to a stressful life event: a dyadic investigation of the roles of positive reframing and perceived benefits.

    Science.gov (United States)

    Samios, Christina; Baran, Shayne

    2018-03-01

    This study examines positive reframing (a form of meaning making), perceived benefits (a form of meanings made) and adjustment in couples who experienced a stressful life event in the past year. This study tested whether couple members' scores were nonindependent and whether one's own perceived benefits was predicted by their own positive reframing (actor effect) as well as their partner's positive reframing (partner effect). Further, this study tested actor and partner effects for the link between perceived benefits and adjustment and whether positive reframing (the initial variable) works through perceived benefits (the mediator) to affect adjustment (the outcome) at the dyadic level. A standard dyadic design was used. Eighty couples completed measures of positive reframing, perceived benefits, and adjustment (depression, anxiety, positive affect, life satisfaction, and relationship satisfaction). Partners' scores on study variables were related, and although only actor effects were found for the path between positive reframing and perceived benefits, both actor and partner effects were found for the path between perceived benefits and adjustment. Mediation was found for actor-actor and actor-partner indirect effects. Results indicate that a greater focus on interpersonal factors is needed to further meaning-making theory and inform practice.

  15. The impact of stressful life events, symptom status, and adherence concerns on quality of life in people living with HIV.

    Science.gov (United States)

    Corless, Inge B; Voss, Joachim; Guarino, A J; Wantland, Dean; Holzemer, William; Jane Hamilton, Mary; Sefcik, Elizabeth; Willard, Suzanne; Kirksey, Kenn; Portillo, Carmen; Rivero Mendez, Marta; Rosa, Maria E; Nicholas, Patrice K; Human, Sarie; Maryland, Mary; Moezzi, Shahnaz; Robinson, Linda; Cuca, Yvette

    2013-01-01

    Studies concerning persons living with HIV (PLWH) report that stressful life events (SLEs) contribute to an exacerbation of symptoms and reduced antiretroviral (ARV) adherence and quality of life (QOL). Little is known about whether these findings are site-specific. Our study's aims were to characterize the type and frequency of SLEs for PLWH in Puerto Rico, South Africa, and the United States, and to assess the impact of SLEs by national site, symptoms, and ARV adherence concerns on QOL. The sample consisted of 704 participants. The total number of SLEs correlated significantly with the total number of symptoms, adherence concerns, and QOL (p ≤ .001). Overall, 27.2% of the variance in QOL was explained by the aforementioned variables. Although SLEs were of concern to PLWH, worries about ARV adherence were of even greater concern. Routine assessment of ARV concerns and SLEs can promote ongoing ARV adherence and improved QOL. Copyright © 2013 Association of Nurses in AIDS Care. Published by Elsevier Inc. All rights reserved.

  16. Incidence of stressful life events and influence of sociodemographic and clinical variables on the onset of first-episode psychosis.

    Science.gov (United States)

    Butjosa, Anna; Gómez-Benito, Juana; Huerta-Ramos, Elena; Del Cacho, Núria; Barajas, Ana; Baños, Iris; Usall, Judith; Dolz, Montserrat; Sánchez, Bernardo; Carlson, Janina; Maria Haro, Josep; Ochoa, Susana

    2016-11-30

    This study presents a quantitative analysis of the incidence of stressful life events (SLEs) and the variables gender, age at onset, family history and psychotic symptoms in patients with first-episode psychosis (FEP). A descriptive, cross-sectional methodology was used to interview 68 patients with FEP between 13 and 47 years of age. The Psychiatric Epidemiology Research Interview Life Events Scale collected one-year period prior to onset of FEP - used to analyse the subcategories academic, work, love and marriage, children, residence, legal affairs, finances and social activities-, Positive and Negative Syndrome Scale, and Clinical Global Impression-Schizophrenia scale were used to assess the relevance of certain SLEs during adolescence. Age at onset showed a significant negative correlation with the categories academic and social activities. By contrast, it showed a positive correlation with work and children. A significant relationship was found between paternal family history and social activities and between maternal family history and academic and love and marriage. Finally, an inverse relationship was observed between negative symptoms and the categories children and finance. Depressive symptoms were significantly correlated with the category academic. Our results show the importance of SLEs during adolescence and suggest that there is a clear need to develop preventive actions that promote effective strategies for dealing with the accumulation of psychosocial stress. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. The emergence of different tail exponents in the distributions of firm size variables

    Science.gov (United States)

    Ishikawa, Atushi; Fujimoto, Shouji; Watanabe, Tsutomu; Mizuno, Takayuki

    2013-05-01

    We discuss a mechanism through which inversion symmetry (i.e., invariance of a joint probability density function under the exchange of variables) and Gibrat’s law generate power-law distributions with different tail exponents. Using a dataset of firm size variables, that is, tangible fixed assets K, the number of workers L, and sales Y, we confirm that these variables have power-law tails with different exponents, and that inversion symmetry and Gibrat’s law hold. Based on these findings, we argue that there exists a plane in the three dimensional space (logK,logL,logY), with respect to which the joint probability density function for the three variables is invariant under the exchange of variables. We provide empirical evidence suggesting that this plane fits the data well, and argue that the plane can be interpreted as the Cobb-Douglas production function, which has been extensively used in various areas of economics since it was first introduced almost a century ago.

  18. Lyapunov exponents and phase diagrams reveal multi-factorial control over TRAIL-induced apoptosis.

    Science.gov (United States)

    Aldridge, Bree B; Gaudet, Suzanne; Lauffenburger, Douglas A; Sorger, Peter K

    2011-11-22

    Receptor-mediated apoptosis proceeds via two pathways: one requiring only a cascade of initiator and effector caspases (type I behavior) and the second requiring an initiator-effector caspase cascade and mitochondrial outer membrane permeabilization (type II behavior). Here, we investigate factors controlling type I versus II phenotypes by performing Lyapunov exponent analysis of an ODE-based model of cell death. The resulting phase diagrams predict that the ratio of XIAP to pro-caspase-3 concentrations plays a key regulatory role: type I behavior predominates when the ratio is low and type II behavior when the ratio is high. Cell-to-cell variability in phenotype is observed when the ratio is close to the type I versus II boundary. By positioning multiple tumor cell lines on the phase diagram we confirm these predictions. We also extend phase space analysis to mutations affecting the rate of caspase-3 ubiquitylation by XIAP, predicting and showing that such mutations abolish all-or-none control over activation of effector caspases. Thus, phase diagrams derived from Lyapunov exponent analysis represent a means to study multi-factorial control over a complex biochemical pathway.

  19. Scaling exponents of the velocity structure functions in the interplanetary medium

    Directory of Open Access Journals (Sweden)

    V. Carbone

    Full Text Available We analyze the scaling exponents of the velocity structure functions, obtained from the velocity fluctuations measured in the interplanetary space plasma. Using the expression for the energy transfer rate which seems the most relevant in describing the evolution of the pseudo-energy densities in the interplanetary medium, we introduce an energy cascade model derived from a simple fragmentation process, which takes into account the intermittency effect. In the absence and in the presence of the large-scale magnetic field decorrelation effect the model reduces to the fluid and the hydromagnetic p-model, respectively. We show that the scaling exponents of the q-th power of the velocity structure functions, as obtained by the model in the absence of the decorrelation effect, furnishes the best-fit to the data analyzed from the Voyager 2 velocity field measurements at 8.5 AU. Our results allow us to hypothesize a new kind of scale-similarity for magnetohydrodynamic turbulence when the decorrelation effect is at work, related to the fourth-order velocity structure function.

  20. Transitional Intermittency Exponents Through Deterministic Boundary-Layer Structures and Empirical Entropic Indices

    Directory of Open Access Journals (Sweden)

    LaVar King Isaacson

    2014-05-01

    Full Text Available A computational procedure is developed to determine initial instabilities within a three-dimensional laminar boundary layer and to follow these instabilities in the streamwise direction through to the resulting intermittency exponents within a fully developed turbulent flow. The fluctuating velocity wave vector component equations are arranged into a Lorenz-type system of equations. The nonlinear time series solution of these equations at the fifth station downstream of the initial instabilities indicates a sequential outward burst process, while the results for the eleventh station predict a strong sequential inward sweep process. The results for the thirteenth station indicate a return to the original instability autogeneration process. The nonlinear time series solutions indicate regions of order and disorder within the solutions. Empirical entropies are defined from decomposition modes obtained from singular value decomposition techniques applied to the nonlinear time series solutions. Empirical entropic indices are obtained from the empirical entropies for two streamwise stations. The intermittency exponents are then obtained from the entropic indices for these streamwise stations that indicate the burst and autogeneration processes.

  1. Automatic detection of ischemic stroke based on scaling exponent electroencephalogram using extreme learning machine

    Science.gov (United States)

    Adhi, H. A.; Wijaya, S. K.; Prawito; Badri, C.; Rezal, M.

    2017-03-01

    Stroke is one of cerebrovascular diseases caused by the obstruction of blood flow to the brain. Stroke becomes the leading cause of death in Indonesia and the second in the world. Stroke also causes of the disability. Ischemic stroke accounts for most of all stroke cases. Obstruction of blood flow can cause tissue damage which results the electrical changes in the brain that can be observed through the electroencephalogram (EEG). In this study, we presented the results of automatic detection of ischemic stroke and normal subjects based on the scaling exponent EEG obtained through detrended fluctuation analysis (DFA) using extreme learning machine (ELM) as the classifier. The signal processing was performed with 18 channels of EEG in the range of 0-30 Hz. Scaling exponents of the subjects were used as the input for ELM to classify the ischemic stroke. The performance of detection was observed by the value of accuracy, sensitivity and specificity. The result showed, performance of the proposed method to classify the ischemic stroke was 84 % for accuracy, 82 % for sensitivity and 87 % for specificity with 120 hidden neurons and sine as the activation function of ELM.

  2. Cycle-expansion method for the Lyapunov exponent, susceptibility, and higher moments

    Science.gov (United States)

    Charbonneau, Patrick; Li, Yue Cathy; Pfister, Henry D.; Yaida, Sho

    2017-09-01

    Lyapunov exponents characterize the chaotic nature of dynamical systems by quantifying the growth rate of uncertainty associated with the imperfect measurement of initial conditions. Finite-time estimates of the exponent, however, experience fluctuations due to both the initial condition and the stochastic nature of the dynamical path. The scale of these fluctuations is governed by the Lyapunov susceptibility, the finiteness of which typically provides a sufficient condition for the law of large numbers to apply. Here, we obtain a formally exact expression for this susceptibility in terms of the Ruelle dynamical ζ function for one-dimensional systems. We further show that, for systems governed by sequences of random matrices, the cycle expansion of the ζ function enables systematic computations of the Lyapunov susceptibility and of its higher-moment generalizations. The method is here applied to a class of dynamical models that maps to static disordered spin chains with interactions stretching over a varying distance and is tested against Monte Carlo simulations.

  3. Predicting the long tail of book sales: Unearthing the power-law exponent

    Science.gov (United States)

    Fenner, Trevor; Levene, Mark; Loizou, George

    2010-06-01

    The concept of the long tail has recently been used to explain the phenomenon in e-commerce where the total volume of sales of the items in the tail is comparable to that of the most popular items. In the case of online book sales, the proportion of tail sales has been estimated using regression techniques on the assumption that the data obeys a power-law distribution. Here we propose a different technique for estimation based on a generative model of book sales that results in an asymptotic power-law distribution of sales, but which does not suffer from the problems related to power-law regression techniques. We show that the proportion of tail sales predicted is very sensitive to the estimated power-law exponent. In particular, if we assume that the power-law exponent of the cumulative distribution is closer to 1.1 rather than to 1.2 (estimates published in 2003, calculated using regression by two groups of researchers), then our computations suggest that the tail sales of Amazon.com, rather than being 40% as estimated by Brynjolfsson, Hu and Smith in 2003, are actually closer to 20%, the proportion estimated by its CEO.

  4. Evaluation of nonlinear properties of epileptic activity using largest Lyapunov exponent

    Science.gov (United States)

    Medvedeva, Tatiana M.; Lüttjohann, Annika; van Luijtelaar, Gilles; Sysoev, Ilya V.

    2016-04-01

    Absence seizures are known to be highly non-linear large amplitude oscillations with a well pronounced main time scale. Whilst the appearance of the main frequency is usually considered as a transition from noisy complex dynamics of baseline EEG to more regular absence activity, the dynamical properties of this type of epileptiformic activity in genetic absence models was not studied precisely. Here, the estimation of the largest Lyapunov exponent from intracranial EEGs of 10 WAG/Rij rats (genetic model of absence epilepsy) was performed. Fragments of 10 seizures and 10 episodes of on-going EEG each of 4 s length were used for each animal, 3 cortical and 2 thalamic channels were analysed. The method adapted for short noisy data was implemented. The positive values of the largest Lyapunov exponent were found as for baseline as for spike wave discharges (SWDs), with values for SWDs being significantly less than for on-going activity. Current findings may indicate that SWD is a chaotic process with a well pronounced main timescale rather than a periodic regime. Also, the absence activity was shown to be less chaotic than the baseline one.

  5. Asymptotic scaling properties and estimation of the generalized Hurst exponents in financial data

    Science.gov (United States)

    Buonocore, R. J.; Aste, T.; Di Matteo, T.

    2017-04-01

    We propose a method to measure the Hurst exponents of financial time series. The scaling of the absolute moments against the aggregation horizon of real financial processes and of both uniscaling and multiscaling synthetic processes converges asymptotically towards linearity in log-log scale. In light of this we found appropriate a modification of the usual scaling equation via the introduction of a filter function. We devised a measurement procedure which takes into account the presence of the filter function without the need of directly estimating it. We verified that the method is unbiased within the errors by applying it to synthetic time series with known scaling properties. Finally we show an application to empirical financial time series where we fit the measured scaling exponents via a second or a fourth degree polynomial, which, because of theoretical constraints, have respectively only one and two degrees of freedom. We found that on our data set there is not clear preference between the second or fourth degree polynomial. Moreover the study of the filter functions of each time series shows common patterns of convergence depending on the momentum degree.

  6. Quantification of scaling exponents and dynamical complexity of microwave refractivity in a tropical climate

    Science.gov (United States)

    Fuwape, Ibiyinka A.; Ogunjo, Samuel T.

    2016-12-01

    Radio refractivity index is used to quantify the effect of atmospheric parameters in communication systems. Scaling and dynamical complexities of radio refractivity across different climatic zones of Nigeria have been studied. Scaling property of the radio refractivity across Nigeria was estimated from the Hurst Exponent obtained using two different scaling methods namely: The Rescaled Range (R/S) and the detrended fluctuation analysis(DFA). The delay vector variance (DVV), Largest Lyapunov Exponent (λ1) and Correlation Dimension (D2) methods were used to investigate nonlinearity and the results confirm the presence of deterministic nonlinear profile in the radio refractivity time series. The recurrence quantification analysis (RQA) was used to quantify the degree of chaoticity in the radio refractivity across the different climatic zones. RQA was found to be a good measure for identifying unique fingerprint and signature of chaotic time series data. Microwave radio refractivity was found to be persistent and chaotic in all the study locations. The dynamics of radio refractivity increases in complexity and chaoticity from the Coastal region towards the Sahelian climate. The design, development and deployment of robust and reliable microwave communication link in the region will be greatly affected by the chaotic nature of radio refractivity in the region.

  7. Stressful life events and cognitive decline in late life: moderation by education and age. The Cache County Study.

    Science.gov (United States)

    Tschanz, Joann T; Pfister, Roxane; Wanzek, Joseph; Corcoran, Chris; Smith, Ken; Tschanz, Brian T; Steffens, David C; Østbye, Truls; Welsh-Bohmer, Kathleen A; Norton, Maria C

    2013-08-01

    Stressful life events (SLE) have been associated with increased dementia risk, but their association with cognitive decline has been inconsistent. In a longitudinal population-based study of older individuals, we examined the association between SLE and cognitive decline, and the role of potential effect modifiers. A total of 2665 non-demented participants of the Cache County Memory Study completed an SLE questionnaire at Wave 2 and were revisited 4 and 7 years later. The events were represented via several scores: total number, subjective rating (negative, positive, and unexpected), and a weighted summary based on their impact. Cognition was assessed at each visit with the modified Mini-Mental State Exam. General linear models were used to examine the association between SLE scores and cognition. Effect modification by age, education, and APOE genotype was tested. Years of formal education (p = 0.006) modified the effect of number of SLE, and age (p = 0.009) modified the effect of negative SLE on the rate of cognitive decline. Faster decline was observed among those with fewer years of education experiencing more SLE and also among younger participants experiencing more negative SLE. There was no association between other indicators of SLE and cognitive decline. APOE genotype did not modify any of the aforementioned associations. The effects of SLE on cognition in late life are complex and vary by individual factors such as age and education. These results may explain some of the contradictory findings in the literature. Copyright © 2012 John Wiley & Sons, Ltd.

  8. The Role of Trauma and Stressful Life Events among Individuals at Clinical High Risk for Psychosis: A Review

    Directory of Open Access Journals (Sweden)

    Danessa Mayo

    2017-04-01

    Full Text Available The experience of childhood trauma (CT and stressful life events (SLEs is associated with subsequent development of a variety of mental health conditions, including psychotic illness. Recent research identifying adolescents and young adults at clinical high risk (CHR for psychosis allows for prospective evaluation of the impact of trauma and adverse life events on psychosis onset and other outcomes, addressing etiological questions that cannot be answered in studies of fully psychotic or non-clinical populations. This article provides a comprehensive review of the current emerging literature on trauma and adverse life events in the CHR population. Up to 80% of CHR youth endorse a lifetime history of childhood traumatic events and victimization (e.g., bullying. Several studies have shown that the experience of CT predicts psychosis onset among CHR individuals, while the literature on the influence of recent SLEs (e.g., death of a loved one remains inconclusive. Multiple models have been proposed to explain the link between trauma and psychosis, including the stress-vulnerability and stress-sensitivity hypotheses, with emphases on both cognitive processes and neurobiological mechanisms (e.g., the hypothalamic–pituitary–adrenal axis. Despite the preponderance of CHR individuals who endorse either CT or SLEs, no clinical trials have been conducted evaluating interventions for trauma in CHR youth to date. Furthermore, the current process of formal identification and assessment of trauma, SLEs, and their impact on CHR youth is inconsistent in research and clinical practice. Recommendations for improving trauma assessment, treatment, and future research directions in the CHR field are provided.

  9. The 5-HTTLPR polymorphism moderates the effect of stressful life events on drinking behavior in college students of African descent.

    Science.gov (United States)

    Kranzler, Henry R; Scott, Denise; Tennen, Howard; Feinn, Richard; Williams, Carla; Armeli, Stephen; Taylor, Robert E; Briggs-Gowan, Margaret J; Covault, Jonathan

    2012-07-01

    Covault et al. [Covault et al. (2007); Biol Psychiatry 61(5): 609-616] reported that the common functional polymorphism, 5-HTTLPR, in the serotonin transporter gene moderated the association between past-year stressful events and daily reports of drinking in a sample of European-American (EA) college students. We examined this effect in college students of African descent. Students recruited at a Historically Black University (n = 564) completed web-based measures of past-year stressful life experiences and daily reports of drinking and heavy drinking over a 30-day period. Participants were genotyped for the tri-allelic 5-HTTLPR polymorphism and dichotomized as low-activity S' allele carriers or high-activity L' homozygotes. Generalized linear models were used to examine the effects of life stress, genotype, and their interaction on the two drinking measures. In students who completed 15 or more daily surveys (n = 393), there was a significant interaction of past-year stressful events, 5-HTTLPR genotype, and gender on the number of drinking days (P = 0.002). Similar findings were obtained in relation to heavy drinking days (P = 0.007). Men showed a main effect of past-year stressful events on both drinking outcomes (P's effects of genotype. In women, the S' allele moderated the impact of past-year life stressors on the frequency of drinking and heavy drinking days (P's college students of African descent, past-year stressful events were associated with more frequent drinking and heavy drinking, an effect that was moderated by the 5-HTTLPR polymorphism. However, in contrast to the findings in EA students, in the current sample, 5-HTTLPR moderated the association only among women. Copyright © 2012 Wiley Periodicals, Inc.

  10. a Comparison of Three Hurst Exponent Approaches to Predict Nascent Bubbles in S&P500 Stocks

    Science.gov (United States)

    Fernández-Martínez, M.; Sánchez-Granero, M. A.; Muñoz Torrecillas, M. J.; McKelvey, Bill

    Since the pioneer contributions due to Vandewalle and Ausloos, the Hurst exponent has been applied by econophysicists as a useful indicator to deal with investment strategies when such a value is above or below 0.5, the Hurst exponent of a Brownian motion. In this paper, we hypothesize that the self-similarity exponent of financial time series provides a reliable indicator for herding behavior (HB) in the following sense: if there is HB, then the higher the price, the more the people will buy. This will generate persistence in the stocks which we shall measure by their self-similarity exponents. Along this work, we shall explore whether there is some connections between the self-similarity exponent of a stock (as a HB indicator) and the stock’s future performance under the assumption that the HB will last for some time. With this aim, three approaches to calculate the self-similarity exponent of a time series are compared in order to determine which performs best to identify the transition from random efficient market behavior to HB and hence, to detect the beginning of a bubble. Generalized Hurst Exponent, Detrended Fluctuation Analysis, and GM2 algorithms have been tested. Traditionally, researchers have focused on identifying the beginning of a crash. We study the beginning of the transition from efficient market behavior to a market bubble, instead. Our empirical results support that the higher (respectively the lower) the self-similarity index, the higher (respectively the lower) the mean of the price change, and hence, the better (respectively the worse) the performance of the corresponding stock. This would imply, as a consequence, that the transition process from random efficient market to HB has started. For experimentation purposes, S&P500 stock Index constituted our main data source.

  11. Exact Critical Exponents for the Antiferromagnetic Quantum Critical Metal in Two Dimensions

    Science.gov (United States)

    Schlief, Andres; Lunts, Peter; Lee, Sung-Sik

    2017-04-01

    Unconventional metallic states which do not support well-defined single-particle excitations can arise near quantum phase transitions as strong quantum fluctuations of incipient order parameters prevent electrons from forming coherent quasiparticles. Although antiferromagnetic phase transitions occur commonly in correlated metals, understanding the nature of the strange metal realized at the critical point in layered systems has been hampered by a lack of reliable theoretical methods that take into account strong quantum fluctuations. We present a nonperturbative solution to the low-energy theory for the antiferromagnetic quantum critical metal in two spatial dimensions. Being a strongly coupled theory, it can still be solved reliably in the low-energy limit as quantum fluctuations are organized by a new control parameter that emerges dynamically. We predict the exact critical exponents that govern the universal scaling of physical observables at low temperatures.

  12. Universal Scaling and Critical Exponents of the Anisotropic Quantum Rabi Model

    Science.gov (United States)

    Liu, Maoxin; Chesi, Stefano; Ying, Zu-Jian; Chen, Xiaosong; Luo, Hong-Gang; Lin, Hai-Qing

    2017-12-01

    We investigate the quantum phase transition of the anisotropic quantum Rabi model, in which the rotating and counterrotating terms are allowed to have different coupling strengths. The model interpolates between two known limits with distinct universal properties. Through a combination of analytic and numerical approaches, we extract the phase diagram, scaling functions, and critical exponents, which determine the universality class at finite anisotropy (identical to the isotropic limit). We also reveal other interesting features, including a superradiance-induced freezing of the effective mass and discontinuous scaling functions in the Jaynes-Cummings limit. Our findings are extended to the few-body quantum phase transitions with N >1 spins, where we expose the same effective parameters, scaling properties, and phase diagram. Thus, a stronger form of universality is established, valid from N =1 up to the thermodynamic limit.

  13. Importance sampling with imperfect cloning for the computation of generalized Lyapunov exponents

    Science.gov (United States)

    Anteneodo, Celia; Camargo, Sabrina; Vallejos, Raúl O.

    2017-12-01

    We revisit the numerical calculation of generalized Lyapunov exponents, L (q ) , in deterministic dynamical systems. The standard method consists of adding noise to the dynamics in order to use importance sampling algorithms. Then L (q ) is obtained by taking the limit noise-amplitude → 0 after the calculation. We focus on a particular method that involves periodic cloning and pruning of a set of trajectories. However, instead of considering a noisy dynamics, we implement an imperfect (noisy) cloning. This alternative method is compared with the standard one and, when possible, with analytical results. As a workbench we use the asymmetric tent map, the standard map, and a system of coupled symplectic maps. The general conclusion of this study is that the imperfect-cloning method performs as well as the standard one, with the advantage of preserving the deterministic dynamics.

  14. Uncertainty in vertical extrapolation of wind statistics: shear-exponent and WAsP/EWA methods

    DEFF Research Database (Denmark)

    Kelly, Mark C.

    for uncertainties inherent in determination of (wind) shear exponents, and subsequent vertical extrapolation of wind speeds. The report further outlines application of the theory and results of Kelly & Troen (2014-6) for gauging the uncertainty inherent in use of the European Wind Atlas (EWA) / WAsP method......This report provides formulations for estimation of uncertainties involved in vertical extrapolation of winds, as well as the total uncertainty incurred when winds observed at one height are extrapolated to turbine hub height for wind resource assessment. This includes new derivations....../푧obs); for larger extrapolations, WAsP-based extrapolation leads to smaller estimated uncertainties than the shear-extrapolation method.A primary motivation for—and part of—this work is the creation of a standard for uncertainty estimation and reporting, which is known as the IEC61400-15. The author is actively...

  15. Parametric Stability of Non-Linearly Elastic Composite Plates by Lyapunov Exponents

    Science.gov (United States)

    GILAT, R.; ABOUDI, J.

    2000-08-01

    The dynamic stability of non-linearly elastic composite plates subjected to periodic in-plane loading is investigated. Infinitely wide plates made of resin matrix composite are considered. The non-linearly elastic behavior of the resin matrix is modelled by the generalized Ramberg-Osgood representation. The effect of the matrix non-linearity on the overall response of the composite is predicted by the micromechanical method of cells. The dynamic stability analysis is performed by evaluating the largest Lyapunov exponent, the sign of which indicates whether the system is stable or not. It is shown that this approach forms a convenient tool for predicting parametric stability of non-linear composite structures.

  16. Fractality Evidence and Long-Range Dependence on Capital Markets: a Hurst Exponent Evaluation

    Science.gov (United States)

    Oprean, Camelia; Tănăsescu, Cristina

    2014-07-01

    Since the existence of market memory could implicate the rejection of the efficient market hypothesis, the aim of this paper is to find any evidence that selected emergent capital markets (eight European and BRIC markets, namely Hungary, Romania, Estonia, Czech Republic, Brazil, Russia, India and China) evince long-range dependence or the random walk hypothesis. In this paper, the Hurst exponent as calculated by R/S fractal analysis and Detrended Fluctuation Analysis is our measure of long-range dependence in the series. The results reinforce our previous findings and suggest that if stock returns present long-range dependence, the random walk hypothesis is not valid anymore and neither is the market efficiency hypothesis.

  17. Dynamic stability of running: The effects of speed and leg amputations on the maximal Lyapunov exponent

    Energy Technology Data Exchange (ETDEWEB)

    Look, Nicole [Department of Applied Mathematics, University of Colorado Boulder, Boulder, Colorado 80309 (United States); Arellano, Christopher J.; Grabowski, Alena M.; Kram, Rodger [Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado 80309 (United States); McDermott, William J. [The Orthopedic Specialty Hospital, Murray, Utah 84107 (United States); Bradley, Elizabeth [Department of Computer Science, University of Colorado Boulder, Boulder, Colorado 80309, USA and Santa Fe Institute, Santa Fe, New Mexico 87501 (United States)

    2013-12-15

    In this paper, we study dynamic stability during running, focusing on the effects of speed, and the use of a leg prosthesis. We compute and compare the maximal Lyapunov exponents of kinematic time-series data from subjects with and without unilateral transtibial amputations running at a wide range of speeds. We find that the dynamics of the affected leg with the running-specific prosthesis are less stable than the dynamics of the unaffected leg and also less stable than the biological legs of the non-amputee runners. Surprisingly, we find that the center-of-mass dynamics of runners with two intact biological legs are slightly less stable than those of runners with amputations. Our results suggest that while leg asymmetries may be associated with instability, runners may compensate for this effect by increased control of their center-of-mass dynamics.

  18. Analysis of the Emergence in Swarm Model Based on Largest Lyapunov Exponent

    Directory of Open Access Journals (Sweden)

    Yu Wu

    2011-01-01

    Full Text Available Emergent behaviors of collective intelligence systems, exemplified by swarm model, have attracted broad interests in recent years. However, current research mostly stops at observational interpretations and qualitative descriptions of emergent phenomena and is essentially short of quantitative analysis and evaluation. In this paper, we conduct a quantitative study on the emergence of swarm model by using chaos analysis of complex dynamic systems. This helps to achieve a more exact understanding of emergent phenomena. In particular, we evaluate the emergent behaviors of swarm model quantitatively by using the chaos and stability analysis of swarm model based on largest Lyapunov exponent. It is concluded that swarm model is at the edge of chaos when emergence occurs, and whether chaotic or stable at the beginning, swarm model will converge to stability with the elapse of time along with interactions among agents.

  19. Dynamic stability of running: The effects of speed and leg amputations on the maximal Lyapunov exponent

    Science.gov (United States)

    Look, Nicole; Arellano, Christopher J.; Grabowski, Alena M.; McDermott, William J.; Kram, Rodger; Bradley, Elizabeth

    2013-12-01

    In this paper, we study dynamic stability during running, focusing on the effects of speed, and the use of a leg prosthesis. We compute and compare the maximal Lyapunov exponents of kinematic time-series data from subjects with and without unilateral transtibial amputations running at a wide range of speeds. We find that the dynamics of the affected leg with the running-specific prosthesis are less stable than the dynamics of the unaffected leg and also less stable than the biological legs of the non-amputee runners. Surprisingly, we find that the center-of-mass dynamics of runners with two intact biological legs are slightly less stable than those of runners with amputations. Our results suggest that while leg asymmetries may be associated with instability, runners may compensate for this effect by increased control of their center-of-mass dynamics.

  20. Toward Synthesis of Solar Wind and Geomagnetic Scaling Exponents: a Fractional Levy Motion Model

    Science.gov (United States)

    Watkins, N. W.; Credgington, D.; Hnat, B.; Freeman, M. P.; Chapman, S. C.; Greenhough, J.

    2005-12-01

    Mandelbrot introduced the concept of fractals to describe the non-Euclidean shape of many aspects of the natural world. In the time series context he proposed the use of fractional Brownian motion (fBm) to model non-negligible temporal persistence, the ``Joseph Effect"; and Lévy flights to quantify large discontinuities, the ``Noah Effect". In space physics, both effects are manifested in the intermittency and long-range correlation which are by now well-established features of geomagnetic indices and their solar wind drivers. In order to capture and quantify the Noah and Joseph effects in one compact model we propose the application of the ``bridging" fractional Lévy motion (fLm) to space physics. We perform an initial evaluation of some previous scaling results in this paradigm, and show how fLm can model the previously observed exponents. We suggest some new directions for the future.

  1. On the improvement of Wiener attack on RSA with small private exponent.

    Science.gov (United States)

    Wu, Mu-En; Chen, Chien-Ming; Lin, Yue-Hsun; Sun, Hung-Min

    2014-01-01

    RSA system is based on the hardness of the integer factorization problem (IFP). Given an RSA modulus N = pq, it is difficult to determine the prime factors p and q efficiently. One of the most famous short exponent attacks on RSA is the Wiener attack. In 1997, Verheul and van Tilborg use an exhaustive search to extend the boundary of the Wiener attack. Their result shows that the cost of exhaustive search is 2r + 8 bits when extending the Weiner's boundary r bits. In this paper, we first reduce the cost of exhaustive search from 2r + 8 bits to 2r + 2 bits. Then, we propose a method named EPF. With EPF, the cost of exhaustive search is further reduced to 2r - 6 bits when we extend Weiner's boundary r bits. It means that our result is 2(14) times faster than Verheul and van Tilborg's result. Besides, the security boundary is extended 7 bits.

  2. Critical exponents of dynamical conductivity in 2D percolative superconductor-insulator transitions: three universality classes.

    Science.gov (United States)

    Karki, Pragalv; Loh, Yen Lee

    2016-11-02

    We simulate three types of random inductor-capacitor (LC) networks on [Formula: see text] square lattices. We calculate the dynamical conductivity using an equation-of-motion method in which timestep error is eliminated and windowing error is minimized. We extract the critical exponent a such that [Formula: see text] at low frequencies. The results suggest that there are three different universality classes. The [Formula: see text] model, with capacitances from each site to ground, has a  =  0.314(4). The [Formula: see text] model, with capacitances along bonds, has a  =  0. The [Formula: see text] model, with both types of capacitances, has a  =  0.304(1). This implies that classical percolative 2D superconductor-insulator transitions (SITs) generically have [Formula: see text] as [Formula: see text]. Therefore, any experiments that give a constant conductivity as [Formula: see text] must be explained in terms of quantum effects.

  3. Stressful life events increase aggression and alcohol use in young carriers of the GABRA2 rs279826/rs279858 A-allele.

    Science.gov (United States)

    Kiive, Evelyn; Laas, Kariina; Vaht, Mariliis; Veidebaum, Toomas; Harro, Jaanus

    2017-08-01

    Research of GABRA2 gene in alcohol use and impulse control suggests its role in aggressive behaviour. The purpose of the present study was to examine the effects of GABRA2 genotype and stressful life events on aggressive behaviour, alcohol use frequency and occurrence of alcohol use disorder in a population representative sample of adolescents followed up from third grade to 25 years of age. The sample consisted of the younger cohort of the longitudinal Estonian Children Personality, Behaviour and Health Study. Aggressive behaviour was rated with the activity scale of af Klinteberg, Illinois Bully Scale and Buss-Perry Aggression Questionnaire. Stressful life events and alcohol use were self-reported. Life history of aggression and lifetime occurrence of psychiatric disorders were estimated in a structured interview. The sample was genotyped for GABRA2 rs279826 and rs279858 polymorphisms that are in strong linkage disequilibrium and yielded very similar findings: Higher number of stressful life events reported at age 15 was associated with increased fighting in A-allele carriers, but not in GG homozygotes. At age 25, A-allele carriers with more stressful life events scored higher on physical aggression than those with less stress, and this was also observed regarding life history of aggression. A-allele carriers exposed to higher stress had consumed alcoholic beverages more frequently at age 15, and by age 25, they had alcohol use disorder with higher prevalence. The results of the present study suggest that the GABRA2 genotype interacts with stress in young people with impact on the development of alcohol use and aggressive behaviour. Copyright © 2017 Elsevier B.V. and ECNP. All rights reserved.

  4. Positive symptoms in first-episode psychosis patients experiencing low maternal care and stressful life events: a pilot study to explore the role of the COMT gene.

    Science.gov (United States)

    Ira, Elisa; De Santi, Katia; Lasalvia, Antonio; Bonetto, Chiara; Zanatta, Gioia; Cristofalo, Doriana; Bertani, Mariaelena; Bissoli, Sarah Saviana; Riolo, Rossana; Gardellin, Francesco; Morandin, Idana; Ramon, Luana; Tansella, Michele; Ruggeri, Mirella; Tosato, Sarah

    2014-09-01

    COMT Val(158)Met moderates the effect of stress on psychotic symptoms. Exposure to stress is also associated with mesolimbic dopamine release in individuals experiencing low maternal care. We therefore test the hypothesis that recent stressful life events are associated with more severe positive symptoms (associated with mesolimbic dopamine release) in first-episode psychosis (FEP) patients who experienced low maternal care during childhood. We hypothesized that COMT Val(158)Met moderates this association. A total of 149 FEP patients recruited within the Psychosis Incident Cohort Outcome Study (PICOS) participated in the present study. Maternal care was assessed by the Parental Bonding Instrument (PBI), stressful life events were collected by the List of Events Scale and positive symptoms were assessed by the Positive and Negative Syndrome Scale (PANSS). We found that low maternal care and recent stressful life events were associated with higher level of positive symptoms at the onset (analysis of variance [ANOVA], p = 0.012), and that patients who were also homozygotes for the COMT Val(158) allele had the highest level of positive symptoms (ANOVA, p = 0.024). Low maternal care and severe stressful life events may contribute to a symptomatology characterized by more severe positive symptoms at the onset, possibly due to an increased mesolimbic dopamine release. Homozygosity for the COMT Val(158) allele seems to confer a biological predisposition to the stress-related hyperactivity of the mesolimbic dopaminergic system. The data imply that the mesolimbic dopaminergic system is involved in the mediation/modulation of the effect of stressful events on the vulnerability for psychosis.

  5. Absorption Angstrom Exponent in AERONET and related data as an indicator of aerosol composition

    Directory of Open Access Journals (Sweden)

    P. B. Russell

    2010-02-01

    Full Text Available Recent results from diverse air, ground, and laboratory studies using both radiometric and in situ techniques show that the fractions of black carbon, organic matter, and mineral dust in atmospheric aerosols determine the wavelength dependence of absorption (often expressed as Absorption Angstrom Exponent, or AAE. Taken together, these results hold promise of improving information on aerosol composition from remote measurements. The main purpose of this paper is to show that AAE values for an Aerosol Robotic Network (AERONET set of retrievals from Sun-sky measurements describing full aerosol vertical columns are also strongly correlated with aerosol composition or type. In particular, we find AAE values near 1 (the theoretical value for black carbon for AERONET-measured aerosol columns dominated by urban-industrial aerosol, larger AAE values for biomass burning aerosols, and the largest AAE values for Sahara dust aerosols. These AERONET results are consistent with results from other, very different, techniques, including solar flux-aerosol optical depth (AOD analyses and airborne in situ analyses examined in this paper, as well as many other previous results. Ambiguities in aerosol composition or mixtures thereof, resulting from intermediate AAE values, can be reduced via cluster analyses that supplement AAE with other variables, for example Extinction Angstrom Exponent (EAE, which is an indicator of particle size. Together with previous results, these results strengthen prospects for determining aerosol composition from space, for example using the Glory Aerosol Polarimetry Sensor (APS, which seeks to provide retrievals of multiwavelength single-scattering albedo (SSA and aerosol optical depth (and therefore aerosol absorption optical depth (AAOD and AAE, as well as shape and other aerosol properties. Multidimensional cluster analyses promise additional information content, for example by using the Ozone Monitoring Instrument (OMI to add AAOD

  6. An early prediction of 25th solar cycle using Hurst exponent

    Science.gov (United States)

    Singh, A. K.; Bhargawa, Asheesh

    2017-11-01

    The analysis of long memory processes in solar activity, space weather and other geophysical phenomena has been a major issue even after the availability of enough data. We have examined the data of various solar parameters like sunspot numbers, 10.7 cm radio flux, solar magnetic field, proton flux and Alfven Mach number observed for the year 1976-2016. We have done the statistical test for persistence of solar activity based on the value of Hurst exponent (H) which is one of the most classical applied methods known as rescaled range analysis. We have discussed the efficiency of this methodology as well as prediction content for next solar cycle based on long term memory. In the present study, Hurst exponent analysis has been used to investigate the persistence of above mentioned (five) solar activity parameters and a simplex projection analysis has been used to predict the ascension time and the maximum number of counts for 25th solar cycle. For available dataset of the year 1976-2016, we have calculated H = 0.86 and 0.82 for sunspot number and 10.7 cm radio flux respectively. Further we have calculated maximum number of counts for sunspot numbers and F10.7 cm index as 102.8± 24.6 and 137.25± 8.9 respectively. Using the simplex projection analysis, we have forecasted that the solar cycle 25th would start in the year 2021 (January) and would last up to the year 2031 (September) with its maxima in June 2024.

  7. Food insecurity, stressful life events and symptoms of anxiety and depression in east Africa: evidence from the Gilgel Gibe growth and development study.

    Science.gov (United States)

    Hadley, C; Tegegn, A; Tessema, F; Cowan, J A; Asefa, M; Galea, S

    2008-11-01

    Common mental disorders are a major contributor to the burden of disease in developing countries. An assessment was carried out of whether food insecurity and exposure to stressful life events, two common features of life in sub-Saharan Africa (SSA), are associated with symptoms of mental disorders among adults. The Gilgel Gibe Growth and Development Study (GGGDS) is an ongoing cohort study in rural Ethiopia. Participants of the GGGDS were randomly selected from households from a complete census of persons living in the area. The Hopkins Symptom Checklist and the Harvard Trauma Questionnaire were used to assess anxiety and depression and post-traumatic stress symptoms. Among 902 adult participants, food insecurity, stressful life events and symptoms of common mental disorders were highly prevalent. In separate multivariate models adjusting for potential confounders, food insecurity and stressful life events were independently associated with high symptoms of depression, anxiety and post-traumatic stress. Potentially modifiable stressors may influence variation in common mental disorders in Ethiopia, and SSA more generally. These findings suggest that the negative effects of food insecurity extend beyond nutritional outcomes and that interventions that promote food security may also positively influence adult mental health in the region.

  8. A novel method for detecting abrupt dynamic change based on the changing Hurst exponent of spatial images

    Science.gov (United States)

    He, W.

    2016-12-01

    The climate system is a classical spatiotemporal evolutionary dynamic system with spatiotemporal correlation characteristics. Based on this, two-dimensional detrended fluctuation analysis (TD-DFA) is used to estimate the Hurst exponent of two-dimensional images. Then, we monitored the change of the Hurst exponent of the images to identify an abrupt dynamic change. We tested the performance of this method with a coupled spatiotemporal dynamic model and found that it works well. The changes in the Hurst exponents of the spatial images are stable when there is no dynamic change in the system, but there will be a clear non-stationary change of the Hurst exponents; for example, the abrupt mean values change if the dynamics of the system change. Thus, the TD-DFA method is suitable for detecting an abrupt dynamic change from natural and artificial images. The spatial images of the NCEP reanalysis of the daily average temperature exhibited fractality. Based on this, we found three non-stationary changes in the Hurst exponents for the NCEP reanalysis of the daily average temperature or for the annual average temperature in the region (60°S-60°N). It can be concluded that the climate system may have incurred three dynamic changes since 1961 on decadal timescales, i.e., in approximately the mid-1970s, the mid-1980s, and between the late 1990s and the early 2000s.

  9. Testing the critical exponent in the relation between stress drop of earthquake and lead time of seismic electric signal

    Directory of Open Access Journals (Sweden)

    E. Dologlou

    2012-08-01

    Full Text Available The application of new data in the power law relation between the stress drop of the earthquake and the lead time of the precursory seismic electric signal led to an exponent which falls in the range of the values of critical exponents for fracture and it is in excellent agreement with a previous one found by (Dologlou, 2012. In addition, this exponent is very close to the one reported by Varotsos and Alexopoulos (1984a, which interconnects the amplitude of the precursory seismic electric signals (SES and the magnitude of the impending earthquake. Hence, the hypothesis that underlying dynamic processes evolving to criticality prevail in the pre-focal area when the SES is emitted is significantly supported.

  10. Influence of finite-time Lyapunov exponents on winter precipitation over the Iberian Peninsula

    Science.gov (United States)

    Garaboa-Paz, Daniel; Lorenzo, Nieves; Pérez-Muñuzuri, Vicente

    2017-05-01

    Seasonal forecasts have improved during the last decades, mostly due to an increase in understanding of the coupled ocean-atmosphere dynamics, and the development of models able to predict the atmosphere variability. Correlations between different teleconnection patterns and severe weather in different parts of the world are constantly evolving and changing. This paper evaluates the connection between winter precipitation over the Iberian Peninsula and the large-scale tropospheric mixing over the eastern Atlantic Ocean. Finite-time Lyapunov exponents (FTLEs) have been calculated from 1979 to 2008 to evaluate this mixing. Our study suggests that significant negative correlations exist between summer FTLE anomalies and winter precipitation over Portugal and Spain. To understand the mechanisms behind this correlation, summer anomalies of the FTLE have also been correlated with other climatic variables such as the sea surface temperature (SST), the sea level pressure (SLP) or the geopotential. The East Atlantic (EA) teleconnection index correlates with the summer FTLE anomalies, confirming their role as a seasonal predictor for winter precipitation over the Iberian Peninsula.

  11. Spike solutions in Gierer#x2013;Meinhardt model with a time dependent anomaly exponent

    Science.gov (United States)

    Nec, Yana

    2018-01-01

    Experimental evidence of complex dispersion regimes in natural systems, where the growth of the mean square displacement in time cannot be characterised by a single power, has been accruing for the past two decades. In such processes the exponent γ(t) in ⟨r2⟩ ∼ tγ(t) at times might be approximated by a piecewise constant function, or it can be a continuous function. Variable order differential equations are an emerging mathematical tool with a strong potential to model these systems. However, variable order differential equations are not tractable by the classic differential equations theory. This contribution illustrates how a classic method can be adapted to gain insight into a system of this type. Herein a variable order Gierer-Meinhardt model is posed, a generic reaction- diffusion system of a chemical origin. With a fixed order this system possesses a solution in the form of a constellation of arbitrarily situated localised pulses, when the components' diffusivity ratio is asymptotically small. The pattern was shown to exist subject to multiple step-like transitions between normal diffusion and sub-diffusion, as well as between distinct sub-diffusive regimes. The analytical approximation obtained permits qualitative analysis of the impact thereof. Numerical solution for typical cross-over scenarios revealed such features as earlier equilibration and non-monotonic excursions before attainment of equilibrium. The method is general and allows for an approximate numerical solution with any reasonably behaved γ(t).

  12. A unified econophysics explanation for the power-law exponents of stock market activity

    Science.gov (United States)

    Gabaix, Xavier; Gopikrishnan, Parameswaran; Plerou, Vasiliki; Stanley, Eugene

    2007-08-01

    We survey a theory (first sketched in Nature in 2003, then fleshed out in the Quarterly Journal of Economics in 2006) of the economic underpinnings of the fat-tailed distributions of a number of financial variables, such as returns and trading volume. Our theory posits that they have a common origin in the strategic trading behavior of very large financial institutions in a relatively illiquid market. We show how the fat-tailed distribution of fund sizes can indeed generate extreme returns and volumes, even in the absence of fundamental news. Moreover, we are able to replicate the individually different empirical values of the power-law exponents for each distribution: 3 for returns, 3/2 for volumes, 1 for the assets under management of large investors. Large investors moderate their trades to reduce their price impact; coupled with a concave price impact function, this leads to volumes being more fat-tailed than returns but less fat-tailed than fund sizes. The trades of large institutions also offer a unified explanation for apparently disconnected empirical regularities that are otherwise a challenge for economic theory.

  13. The Tail Exponent for Stock Returns in Bursa Malaysia for 2003-2008

    Science.gov (United States)

    Rusli, N. H.; Gopir, G.; Usang, M. D.

    2010-07-01

    A developed discipline of econophysics that has been introduced is exhibiting the application of mathematical tools that are usually applied to the physical models for the study of financial models. In this study, an analysis of the time series behavior of several blue chip and penny stock companies in Main Market of Bursa Malaysia has been performed. Generally, the basic quantity being used is the relative price changes or is called the stock price returns, contains daily-sampled data from the beginning of 2003 until the end of 2008, containing 1555 trading days recorded. The aim of this paper is to investigate the tail exponent in tails of the distribution for blue chip stocks and penny stocks financial returns in six years period. By using a standard regression method, it is found that the distribution performed double scaling on the log-log plot of the cumulative probability of the normalized returns. Thus we calculate α for a small scale return as well as large scale return. Based on the result obtained, it is found that the power-law behavior for the probability density functions of the stock price absolute returns P(z)˜z-α with values lying inside and outside the Lévy stable regime with values α>2. All the results were discussed in detail.

  14. Designing Hyperchaotic Cat Maps With Any Desired Number of Positive Lyapunov Exponents.

    Science.gov (United States)

    Hua, Zhongyun; Yi, Shuang; Zhou, Yicong; Li, Chengqing; Wu, Yue

    2017-01-04

    Generating chaotic maps with expected dynamics of users is a challenging topic. Utilizing the inherent relation between the Lyapunov exponents (LEs) of the Cat map and its associated Cat matrix, this paper proposes a simple but efficient method to construct an n-dimensional (n-D) hyperchaotic Cat map (HCM) with any desired number of positive LEs. The method first generates two basic n-D Cat matrices iteratively and then constructs the final n-D Cat matrix by performing similarity transformation on one basic n-D Cat matrix by the other. Given any number of positive LEs, it can generate an n-D HCM with desired hyperchaotic complexity. Two illustrative examples of n-D HCMs were constructed to show the effectiveness of the proposed method, and to verify the inherent relation between the LEs and Cat matrix. Theoretical analysis proves that the parameter space of the generated HCM is very large. Performance evaluations show that, compared with existing methods, the proposed method can construct n-D HCMs with lower computation complexity and their outputs demonstrate strong randomness and complex ergodicity.

  15. Landau-Ginzburg Limit of Black Hole's Quantum Portrait: Self Similarity and Critical Exponent

    CERN Document Server

    Dvali, Gia

    2012-01-01

    Recently we have suggested that the microscopic quantum description of a black hole is an overpacked self-sustained Bose-condensate of N weakly-interacting soft gravitons, which obeys the rules of 't Hooft's large-N physics. In this note we derive an effective Landau-Ginzburg Lagrangian for the condensate and show that it becomes an exact description in a semi-classical limit that serves as the black hole analog of 't Hooft's planar limit. The role of a weakly-coupled Landau-Ginzburg order parameter is played by N. This description consistently reproduces the known properties of black holes in semi-classical limit. Hawking radiation, as the quantum depletion of the condensate, is described by the slow-roll of the field N. In the semiclassical limit, where black holes of arbitrarily small size are allowed, the equation of depletion is self similar leading to a scaling law for the black hole size with critical exponent 1/3.

  16. Generalized Hurst exponent estimates differentiate EEG signals of healthy and epileptic patients

    Science.gov (United States)

    Lahmiri, Salim

    2018-01-01

    The aim of our current study is to check whether multifractal patterns of the electroencephalographic (EEG) signals of normal and epileptic patients are statistically similar or different. In this regard, the generalized Hurst exponent (GHE) method is used for robust estimation of the multifractals in each type of EEG signals, and three powerful statistical tests are performed to check existence of differences between estimated GHEs from healthy control subjects and epileptic patients. The obtained results show that multifractals exist in both types of EEG signals. Particularly, it was found that the degree of fractal is more pronounced in short variations of normal EEG signals than in short variations of EEG signals with seizure free intervals. In contrary, it is more pronounced in long variations of EEG signals with seizure free intervals than in normal EEG signals. Importantly, both parametric and nonparametric statistical tests show strong evidence that estimated GHEs of normal EEG signals are statistically and significantly different from those with seizure free intervals. Therefore, GHEs can be efficiently used to distinguish between healthy and patients suffering from epilepsy.

  17. Competitive autocatalytic reactions in chaotic flows with diffusion: Prediction using finite-time Lyapunov exponents

    Energy Technology Data Exchange (ETDEWEB)

    Schlick, Conor P., E-mail: conorschlick2015@u.northwestern.edu [Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois 60208 (United States); Umbanhowar, Paul B. [Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Ottino, Julio M. [Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208 (United States); The Northwestern Institute on Complex Systems (NICO), Northwestern University, Evanston, Illinois 60208 (United States); Lueptow, Richard M., E-mail: r-lueptow@northwestern.edu [Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208 (United States); The Northwestern Institute on Complex Systems (NICO), Northwestern University, Evanston, Illinois 60208 (United States)

    2014-03-15

    We investigate chaotic advection and diffusion in autocatalytic reactions for time-periodic sine flow computationally using a mapping method with operator splitting. We specifically consider three different autocatalytic reaction schemes: a single autocatalytic reaction, competitive autocatalytic reactions, which can provide insight into problems of chiral symmetry breaking and homochirality, and competitive autocatalytic reactions with recycling. In competitive autocatalytic reactions, species B and C both undergo an autocatalytic reaction with species A such that A+B→2B and A+C→2C. Small amounts of initially spatially localized B and C and a large amount of spatially homogeneous A are advected by the velocity field, diffuse, and react until A is completely consumed and only B and C remain. We find that local finite-time Lyapunov exponents (FTLEs) can accurately predict the final average concentrations of B and C after the reaction completes. The species that starts in the region with the larger FTLE has, with high probability, the larger average concentration at the end of the reaction. If B and C start in regions with similar FTLEs, their average concentrations at the end of the reaction will also be similar. When a recycling reaction is added, the system evolves towards a single species state, with the FTLE often being useful in predicting which species fills the entire domain and which is depleted. The FTLE approach is also demonstrated for competitive autocatalytic reactions in journal bearing flow, an experimentally realizable flow that generates chaotic dynamics.

  18. Hurst exponent: A Brownian approach to characterize the nonlinear behavior of red blood cells deformability

    Science.gov (United States)

    Mancilla Canales, M. A.; Leguto, A. J.; Riquelme, B. D.; León, P. Ponce de; Bortolato, S. A.; Korol, A. M.

    2017-12-01

    Ektacytometry techniques quantifies red blood cells (RBCs) deformability by measuring the elongation of suspended RBCs subjected to shear stress. Raw shear stress elongation plots are difficult to understand, thus most research papers apply data reduction methods characterizing the relationship between curve fitting. Our approach works with the naturally generated photometrically recorded time series of the diffraction pattern of several million of RBCs subjected to shear stress, and applies nonlinear quantifiers to study the fluctuations of these elongations. The development of new quantitative methods is crucial for restricting the subjectivity in the study of the cells behavior, mainly if they are capable of analyze at the same time biological and mechanical aspects of the cells in flowing conditions and compare their dynamics. A patented optical system called Erythrocyte Rheometer was used to evaluate viscoelastic properties of erythrocytes by Ektacytometry. To analyze cell dynamics we used the technique of Time Delay Coordinates, False Nearest Neighbors, the forecasting procedure proposed by Sugihara and May, and Hurst exponent. The results have expressive meaning on comparing healthy samples with parasite treated samples, suggesting that apparent noise associated with deterministic chaos can be used not only to distinguish but also to characterize biological and mechanical aspects of cells at the same time in flowing conditions.

  19. Presence of nonlinearity in intracranial EEG recordings: detected by Lyapunov exponents

    Science.gov (United States)

    Liu, Chang-Chia; Shiau, Deng-Shan; Chaovalitwongse, W. Art; Pardalos, Panos M.; Sackellares, J. C.

    2007-11-01

    In this communication, we performed nonlinearity analysis in the EEG signals recorded from patients with temporal lobe epilepsy (TLE). The largest Lyapunov exponent (Lmax) and phase randomization surrogate data technique were employed to form the statistical test. EEG recordings were acquired invasively from three patients in six brain regions (left and right temporal depth, sub-temporal and orbitofrontal) with 28-32 depth electrodes placed in depth and subdural of the brain. All three patients in this study have unilateral epileptic focus region on the right hippocampus(RH). Nonlinearity was detected by comparing the Lmax profiles of the EEG recordings to its surrogates. The nonlinearity was seen in all different states of the patient with the highest found in post-ictal state. Further our results for all patients exhibited higher degree of differences, quantified by paired t-test, in Lmax values between original and its surrogate from EEG signals recorded from epileptic focus regions. The results of this study demonstrated the Lmax is capable to capture spatio-temporal dynamics that may not be able to detect by linear measurements in the intracranial EEG recordings.

  20. Dominant Lyapunov Exponent and Approximate Entropy in Heart Rate Variability during Emotional Visual Elicitation

    Directory of Open Access Journals (Sweden)

    Gaetano eValenza

    2012-02-01

    Full Text Available In this work we characterized the nonlinear complexity of Heart Rate Variability (HRV in short time series. The complexity of HRV signal was evaluated during emotional visual elicitation by using Dominant Lyapunov Exponents (DLE and Approximate Entropy (ApEn. We adopted a simplified model of emotion derived from the Circumplex Model of Affects (CMA, in which emotional mechanisms are conceptualized in two dimensions by the terms of valence and arousal. Following CMA model, a set of standardized visual stimuli in terms of arousal and valence gathered from the International Affective Picture System (IAPS was administered to a group of 35 healthy volunteers. Experimental session consisted of eight sessions alternating neutral images with high arousal content images. Several works can be found in the literature showing a chaotic dynamics of HRV during rest or relax conditions. The outcomes of this work showed a clear switching mechanism between regular and chaotic dynamics when switching from neutral to arousal elicitation. Accordingly, the mean ApEn decreased with statistical significance during arousal elicitation and the DLE became negative. Results are very promising and could be profitably exploited to improve the accuracy of emotion recognition systems based on HRV time series analysis.

  1. Characteristic distribution of finite-time Lyapunov exponents for chimera states

    Science.gov (United States)

    Botha, André E.

    2016-01-01

    Our fascination with chimera states stems partially from the somewhat paradoxical, yet fundamental trait of identical, and identically coupled, oscillators to split into spatially separated, coherently and incoherently oscillating groups. While the list of systems for which various types of chimeras have already been detected continues to grow, there is a corresponding increase in the number of mathematical analyses aimed at elucidating the fundamental reasons for this surprising behaviour. Based on the model systems, there are strong indications that chimera states may generally be ubiquitous in naturally occurring systems containing large numbers of coupled oscillators – certain biological systems and high-Tc superconducting materials, for example. In this work we suggest a new way of detecting and characterising chimera states. Specifically, it is shown that the probability densities of finite-time Lyapunov exponents, corresponding to chimera states, have a definite characteristic shape. Such distributions could be used as signatures of chimera states, particularly in systems for which the phases of all the oscillators cannot be measured directly. For such cases, we suggest that chimera states could perhaps be detected by reconstructing the characteristic distribution via standard embedding techniques, thus making it possible to detect chimera states in systems where they could otherwise exist unnoticed. PMID:27374473

  2. Detection on Structural Sudden Damage Using Continuous Wavelet Transform and Lipschitz Exponent

    Directory of Open Access Journals (Sweden)

    Bo Chen

    2015-01-01

    Full Text Available The degradation of civil engineering structures may lead to a sudden stiffness reduction in a structure and such a sudden damage will cause a discontinuity in the dynamic responses. The detection on structural sudden damage has been actively carried out in this study. The signal singularity of the acceleration responses with sudden stiffness reduction is characterized by the coefficients of continuous wavelet transform with fine scales. A detection approach based on the CWT is proposed in terms of the decomposed detail coefficients of continuous wavelet transform to detect the damage time instant and location. The Lipschitz exponent is mathematically used to estimate the local properties of certain function and is applied to reflect the damage severity. Numerical simulation using a five-story shear building under different types of excitation is carried out to assess the validity of the proposed detection approach for the building at different damage levels. The sensitivity of the damage index to the intensity and frequency range of measurement noise is also investigated. The effects of both measurement noise intensity and frequency range on the damage detection are numerically investigated.

  3. Critical exponents for two-dimensional condensation of organic adsorbates at the mercury-aqueous solution interface

    Science.gov (United States)

    Pushpalatha, K.; Sangaranarayanan, M. V.

    1997-07-01

    The evaluation of critical exponent β for two-dimensional condensation of organic adsorbates at the mercury-aqueous solution interface is carried out using spin- {1}/{2} generalized Ising model formalism. The estimated value is in agreement with Onsager's value of 0.125 pertaining to two-dimensional Ising model with nearest neighbour interaction energies.

  4. Orbital Exponent Optimization in Elementary VB Calculations of the Chemical Bond in the Ground State of Simple Molecular Systems

    Science.gov (United States)

    Magnasco, Valerio

    2008-01-01

    Orbital exponent optimization in the elementary ab-initio VB calculation of the ground states of H[subscript 2][superscript +], H[subscript 2], He[subscript 2][superscript +], He[subscript 2] gives a fair description of the exchange-overlap component of the interatomic interaction that is important in the bond region. Correct bond lengths and…

  5. Strong correlations between the exponent α and the particle number for a Renyi monoatomic gas in Gibbs' statistical mechanics

    Science.gov (United States)

    Plastino, A.; Rocca, M. C.

    2017-06-01

    Appealing to the 1902 Gibbs formalism for classical statistical mechanics (SM)—the first SM axiomatic theory ever that successfully explained equilibrium thermodynamics—we show that already at the classical level there is a strong correlation between Renyi's exponent α and the number of particles for very simple systems. No reference to heat baths is needed for such a purpose.

  6. Optimal detrended fluctuation analysis as a tool for the determination of the roughness exponent of the mounded surfaces

    Science.gov (United States)

    Luis, Edwin E. Mozo; de Assis, Thiago A.; Ferreira, Silvio C.

    2017-04-01

    We present an optimal detrended fluctuation analysis (DFA) and apply it to evaluate the local roughness exponent in nonequilibrium surface growth models with mounded morphology. Our method consists in analyzing the height fluctuations computing the shortest distance of each point of the profile to a detrending curve that fits the surface within the investigated interval. We compare the optimal DFA (ODFA) with both the standard DFA and nondetrended analysis. We validate the ODFA method considering a one-dimensional model in the Kardar-Parisi-Zhang universality class starting from a mounded initial condition. We applied the methods to the Clarke-Vvedensky (CV) model in 2 +1 dimensions with thermally activated surface diffusion and absence of step barriers. It is expected that this model belongs to the nonlinear molecular beam epitaxy (nMBE) universality class. However, an explicit observation of the roughness exponent in agreement with the nMBE class was still missing. The effective roughness exponent obtained with ODFA agrees with the value expected for the nMBE class, whereas using the other methods it does not agree. We also characterize the transient anomalous scaling of the CV model and obtained that the corresponding exponent is in agreement with the value reported for other nMBE models with weaker corrections to the scaling.

  7. Prevalence of psychological disorders, sleep disturbance and stressful life events and their relationships with disease parameters in Chinese patients with ankylosing spondylitis.

    Science.gov (United States)

    Jiang, Yutong; Yang, Mingcan; Lv, Qing; Qi, Jun; Lin, Zhiming; Liao, Zetao; Zhang, Yanli; Wu, Husheng; Song, Hui; Zhan, Feng; Liu, Shengyun; Gao, Guanmin; Hu, Shaoxian; Li, Yinong; Shen, Lingxun; Huang, Anbing; Wei, Qiujing; Cao, Shuangyan; Gu, Jieruo

    2017-11-25

    Our aim was to investigate the prevalence of psychological disorders, sleep disturbance, and stressful life events in Chinese patients with ankylosing spondylitis (AS) and healthy controls, to assess the correlation between psychological and disease-related variables, and finally to detect powerful factors in predicting anxiety and depression. AS patients diagnosed with the modified New York criteria and healthy controls were enrolled from China. Participants completed a set of questionnaires, including demographic and disease parameters, Zung self-rating anxiety scale (SAS), Zung self-rating depression scale (SDS), the Pittsburgh Sleep Quality Index questionnaire (PSQI), and the Social Readjustment Rating Scale (SRRS). The relationship between psychological and other variables was explored. Stepwise multiple regression was used to determine the contributors to each disorder. Of all the 2772 AS patients, 79.1% were male. Mean age was 28.99 ± 8.87 years. Prevalence of anxiety, depression, and sleep disturbance was 31.6% (95% CI, 29.9, to 33.4), 59.3% (95% CI, 57.5, to 61.2), and 31.0% (95% CI, 29.3, to 36.7), respectively. 35.3% had stimulus of psychological and social elements (SPSE). Compared with healthy controls, AS patients had more severe psychological disorders, sleep disturbance, and stressful life events (P < 0.01). SDS, overall pain, BASFI, and sleep disturbance were significant contributors of the SAS scores (P < 0.03). SAS, less years of education, and sleep duration were significant contributors of SDS (P < 0.01). AS patients had more anxiety, depression, stressful life events, and sleep disturbance than healthy controls. Pain, functional limitation, sleep disturbance, and education were major contributors to psychological disorders.

  8. Association of Stressful Life Events with Psychological Problems: A Large-Scale Community-Based Study Using Grouped Outcomes Latent Factor Regression with Latent Predictors

    Directory of Open Access Journals (Sweden)

    Akbar Hassanzadeh

    2017-01-01

    Full Text Available Objective. The current study is aimed at investigating the association between stressful life events and psychological problems in a large sample of Iranian adults. Method. In a cross-sectional large-scale community-based study, 4763 Iranian adults, living in Isfahan, Iran, were investigated. Grouped outcomes latent factor regression on latent predictors was used for modeling the association of psychological problems (depression, anxiety, and psychological distress, measured by Hospital Anxiety and Depression Scale (HADS and General Health Questionnaire (GHQ-12, as the grouped outcomes, and stressful life events, measured by a self-administered stressful life events (SLEs questionnaire, as the latent predictors. Results. The results showed that the personal stressors domain has significant positive association with psychological distress (β=0.19, anxiety (β=0.25, depression (β=0.15, and their collective profile score (β=0.20, with greater associations in females (β=0.28 than in males (β=0.13 (all P<0.001. In addition, in the adjusted models, the regression coefficients for the association of social stressors domain and psychological problems profile score were 0.37, 0.35, and 0.46 in total sample, males, and females, respectively (P<0.001. Conclusion. Results of our study indicated that different stressors, particularly those socioeconomic related, have an effective impact on psychological problems. It is important to consider the social and cultural background of a population for managing the stressors as an effective approach for preventing and reducing the destructive burden of psychological problems.

  9. Hurst Exponent Analysis of Resting-State fMRI Signal Complexity across the Adult Lifespan

    Directory of Open Access Journals (Sweden)

    Jianxin Dong

    2018-02-01

    Full Text Available Exploring functional information among various brain regions across time enables understanding of healthy aging process and holds great promise for age-related brain disease diagnosis. This paper proposed a method to explore fractal complexity of the resting-state functional magnetic resonance imaging (rs-fMRI signal in the human brain across the adult lifespan using Hurst exponent (HE. We took advantage of the examined rs-fMRI data from 116 adults 19 to 85 years of age (44.3 ± 19.4 years, 49 females from NKI/Rockland sample. Region-wise and voxel-wise analyses were performed to investigate the effects of age, gender, and their interaction on complexity. In region-wise analysis, we found that the healthy aging is accompanied by a loss of complexity in frontal and parietal lobe and increased complexity in insula, limbic, and temporal lobe. Meanwhile, differences in HE between genders were found to be significant in parietal lobe (p = 0.04, corrected. However, there was no interaction between gender and age. In voxel-wise analysis, the significant complexity decrease with aging was found in frontal and parietal lobe, and complexity increase was found in insula, limbic lobe, occipital lobe, and temporal lobe with aging. Meanwhile, differences in HE between genders were found to be significant in frontal, parietal, and limbic lobe. Furthermore, we found age and sex interaction in right parahippocampal gyrus (p = 0.04, corrected. Our findings reveal HE variations of the rs-fMRI signal across the human adult lifespan and show that HE may serve as a new parameter to assess healthy aging process.

  10. Finite-time Lyapunov exponent-based analysis for compressible flows

    Science.gov (United States)

    González, D. R.; Speth, R. L.; Gaitonde, D. V.; Lewis, M. J.

    2016-08-01

    The finite-time Lyapunov exponent (FTLE) technique has shown substantial success in analyzing incompressible flows by capturing the dynamics of coherent structures. Recent applications include river and ocean flow patterns, respiratory tract dynamics, and bio-inspired propulsors. In the present work, we extend FTLE to the compressible flow regime so that coherent structures, which travel at convective speeds, can be associated with waves traveling at acoustic speeds. This is particularly helpful in the study of jet acoustics. We first show that with a suitable choice of integration time interval, FTLE can extract wave dynamics from the velocity field. The integration time thus acts as a pseudo-filter separating coherent structures from waves. Results are confirmed by examining forward and backward FTLE coefficients for several simple, well-known acoustic fields. Next, we use this analysis to identify events associated with intermittency in jet noise pressure probe data. Although intermittent events are known to be dominant causes of jet noise, their direct source in the turbulent jet flow has remained unexplained. To this end, a Large-Eddy Simulation of a Mach 0.9 jet is subjected to FTLE to simultaneously examine, and thus expose, the causal relationship between coherent structures and the corresponding acoustic waves. Results show that intermittent events are associated with entrainment in the initial roll up region and emissive events downstream of the potential-core collapse. Instantaneous acoustic disturbances are observed to be primarily induced near the collapse of the potential core and continue propagating towards the far-field at the experimentally observed, approximately 30° angle relative to the jet axis.

  11. The Relationship Between Stressful Life Events and Axis I Diagnoses Among Adolescent Offspring of Probands With Bipolar and Non-Bipolar Psychiatric Disorders and Healthy Controls: The Pittsburgh Bipolar Offspring Study (BIOS).

    Science.gov (United States)

    Pan, Lisa A; Goldstein, Tina R; Rooks, Brian T; Hickey, Mary; Fan, Jie Yu; Merranko, John; Monk, Kelly; Diler, Rasim S; Sakolsky, Dara J; Hafeman, Danella; Iyengar, Satish; Goldstein, Benjamin; Kupfer, David J; Axelson, David A; Brent, David A; Birmaher, Boris

    2017-03-01

    Previous studies have explored the role of stressful life events in the development of mood disorders. We examined the frequency and nature of stressful life events as measured by the Stressful Life Events Schedule (SLES) among 3 groups of adolescent offspring of probands with bipolar (BD), with non-BD psychiatric disorders, and healthy controls. Furthermore, we examined the relationship between stressful life events and the presence of DSM-IV Axis I disorders in these offspring. Stressful life events were characterized as dependent, independent, or uncertain (neither dependent nor independent) and positive, negative, or neutral (neither positive nor negative). Offspring of probands with BD aged 13-18 years (n = 269), demographically matched offspring of probands with non-BD Axis I disorders (n = 88), and offspring of healthy controls (n = 81) from the Pittsburgh Bipolar Offspring Study were assessed from 2002 to 2007 with standardized instruments at intake. Probands completed the SLES for their offspring for life events within the prior year. Life events were evaluated with regard to current Axis I diagnoses in offspring after adjusting for confounds. After adjusting for demographic and clinical between-group differences (in probands and offspring), offspring of probands with BD had greater independent (χ² = 11.96, P < .04) and neutral (χ² = 17.99, P < .003) life events compared with offspring of healthy controls and greater number of more severe stressful life events than offspring of healthy controls, but not offspring of probands with non-BD. Offspring of BD probands with comorbid substance use disorder reported more independent stressful life events compared to those without comorbid substance use disorder (P = .024). Greater frequency and severity of stressful life events were associated with current Axis I disorder in offspring of both probands with BD and probands with other Axis I disorders regardless of dependency or valence. Greater frequency and

  12. Association of perceived stress with stressful life events, lifestyle and sociodemographic factors: a large-scale community-based study using logistic quantile regression.

    Science.gov (United States)

    Feizi, Awat; Aliyari, Roqayeh; Roohafza, Hamidreza

    2012-01-01

    The present paper aimed at investigating the association between perceived stress and major life events stressors in Iranian general population. In a cross-sectional large-scale community-based study, 4583 people aged 19 and older, living in Isfahan, Iran, were investigated. Logistic quantile regression was used for modeling perceived stress, measured by GHQ questionnaire, as the bounded outcome (dependent), variable, and as a function of most important stressful life events, as the predictor variables, controlling for major lifestyle and sociodemographic factors. This model provides empirical evidence of the predictors' effects heterogeneity depending on individual location on the distribution of perceived stress. The results showed that among four stressful life events, family conflicts and social problems were more correlated with level of perceived stress. Higher levels of education were negatively associated with perceived stress and its coefficients monotonically decrease beyond the 30th percentile. Also, higher levels of physical activity were associated with perception of low levels of stress. The pattern of gender's coefficient over the majority of quantiles implied that females are more affected by stressors. Also high perceived stress was associated with low or middle levels of income. The results of current research suggested that in a developing society with high prevalence of stress, interventions targeted toward promoting financial and social equalities, social skills training, and healthy lifestyle may have the potential benefits for large parts of the population, most notably female and lower educated people.

  13. Association of Perceived Stress with Stressful Life Events, Lifestyle and Sociodemographic Factors: A Large-Scale Community-Based Study Using Logistic Quantile Regression

    Science.gov (United States)

    Feizi, Awat; Aliyari, Roqayeh; Roohafza, Hamidreza

    2012-01-01

    Objective. The present paper aimed at investigating the association between perceived stress and major life events stressors in Iranian general population. Methods. In a cross-sectional large-scale community-based study, 4583 people aged 19 and older, living in Isfahan, Iran, were investigated. Logistic quantile regression was used for modeling perceived stress, measured by GHQ questionnaire, as the bounded outcome (dependent), variable, and as a function of most important stressful life events, as the predictor variables, controlling for major lifestyle and sociodemographic factors. This model provides empirical evidence of the predictors' effects heterogeneity depending on individual location on the distribution of perceived stress. Results. The results showed that among four stressful life events, family conflicts and social problems were more correlated with level of perceived stress. Higher levels of education were negatively associated with perceived stress and its coefficients monotonically decrease beyond the 30th percentile. Also, higher levels of physical activity were associated with perception of low levels of stress. The pattern of gender's coefficient over the majority of quantiles implied that females are more affected by stressors. Also high perceived stress was associated with low or middle levels of income. Conclusions. The results of current research suggested that in a developing society with high prevalence of stress, interventions targeted toward promoting financial and social equalities, social skills training, and healthy lifestyle may have the potential benefits for large parts of the population, most notably female and lower educated people. PMID:23091560

  14. Association of Perceived Stress with Stressful Life Events, Lifestyle and Sociodemographic Factors: A Large-Scale Community-Based Study Using Logistic Quantile Regression

    Directory of Open Access Journals (Sweden)

    Awat Feizi

    2012-01-01

    Full Text Available Objective. The present paper aimed at investigating the association between perceived stress and major life events stressors in Iranian general population. Methods. In a cross-sectional large-scale community-based study, 4583 people aged 19 and older, living in Isfahan, Iran, were investigated. Logistic quantile regression was used for modeling perceived stress, measured by GHQ questionnaire, as the bounded outcome (dependent, variable, and as a function of most important stressful life events, as the predictor variables, controlling for major lifestyle and sociodemographic factors. This model provides empirical evidence of the predictors’ effects heterogeneity depending on individual location on the distribution of perceived stress. Results. The results showed that among four stressful life events, family conflicts and social problems were more correlated with level of perceived stress. Higher levels of education were negatively associated with perceived stress and its coefficients monotonically decrease beyond the 30th percentile. Also, higher levels of physical activity were associated with perception of low levels of stress. The pattern of gender’s coefficient over the majority of quantiles implied that females are more affected by stressors. Also high perceived stress was associated with low or middle levels of income. Conclusions. The results of current research suggested that in a developing society with high prevalence of stress, interventions targeted toward promoting financial and social equalities, social skills training, and healthy lifestyle may have the potential benefits for large parts of the population, most notably female and lower educated people.

  15. Influence of granulometry in the Hurst exponent of air liquid interfaces formed during capillary rising in a granular media

    Directory of Open Access Journals (Sweden)

    Gontijo Guilherme L.

    2017-01-01

    Full Text Available We report results concerning the fractal dimension of a air/fluid interface formed during the capillary rising of a fluid into a dense granular media. The system consists in a modified Hele-Shaw cell filled with grains at different granulometries and confined in a narrow gap between the glass plates. The system is then placed onto a water reservoir, and the liquid penetrates the medium due to capillary forces. We measure the Hurst exponent of the liquid/air interface with help of image processing, and follow the temporal evolution of the profiles. We observe that the Hurst exponent can be related with the granulometry, but the range of values are odd to the predicted values from models or theory.

  16. Emden equation involving the critical Sobolev exponent with the third-kind boundary condition in S3

    OpenAIRE

    Kosaka, Atsushi

    2012-01-01

    We consider a positive solution of the Emden equation with the critical Sobolev exponent on a geodesic ball in S3. In the case of the Dirichlet boundary condition, Bandle and Peletier [2] proved the precise result on the existence of a positive radial solution. We investigate the same equation with the third kind boundary condition and obtain a more general result. Namely we prove that the existence and the nonexistence of solutions depend on the geodesic radius and the boundary condition. Mo...

  17. Quantification of scaling exponent with Crossover type phenomena for different types of forcing in DC glow discharge plasma

    Science.gov (United States)

    Saha, Debajyoti; Shaw, Pankaj Kumar; Ghosh, Sabuj; Janaki, M. S.; Sekar Iyengar, A. N.

    2018-01-01

    We have carried out a detailed study of scaling region using detrended fractal analysis test by applying different forcing likewise noise, sinusoidal, square on the floating potential fluctuations acquired under different pressures in a DC glow discharge plasma. The transition in the dynamics is observed through recurrence plot techniques which is an efficient method to observe the critical regime transitions in dynamics. The complexity of the nonlinear fluctuation has been revealed with the help of recurrence quantification analysis which is a suitable tool for investigating recurrence, an ubiquitous feature providing a deep insight into the dynamics of real dynamical system. An informal test for stationarity which checks for the compatibility of nonlinear approximations to the dynamics made in different segments in a time series has been proposed. In case of sinusoidal, noise, square forcing applied on fluctuation acquired at P = 0.12 mbar only one dominant scaling region is observed whereas the forcing applied on fluctuation (P = 0.04 mbar) two prominent scaling regions have been explored reliably using different forcing amplitudes indicating the signature of crossover phenomena. Furthermore a persistence long range behavior has been observed in one of these scaling regions. A comprehensive study of the quantification of scaling exponents has been carried out with the increase in amplitude and frequency of sinusoidal, square type of forcings. The scalings exponent is envisaged to be the roughness of the time series. The method provides a single quantitative idea of the scaling exponent to quantify the correlation properties of a signal.

  18. Autocorrelation analysis for the unbiased determination of power-law exponents in single-quantum-dot blinking

    CERN Document Server

    Houel, J; Cajgfinger, T; Ledoux, G; Amans, D; Aubret, A; Dominjon, A; Ferriol, S; Barbier, R; Nasilowski, M; Lhuillier, E; Dubertret, B; Dujardin, C; Kulzer, F

    2014-01-01

    We present an unbiased and robust analysis method for power-law blinking statistics in the photoluminescence of single nano-emitters, allowing us to extract both the bright- and dark-state power-law exponents from the emitters' intensity autocorrelation functions. As opposed to the widely-used threshold method, our technique therefore does not require discriminating the emission levels of bright and dark states in the experimental intensity timetraces. We rely on the simultaneous recording of 450 emission timetraces of single CdSe/CdS core/shell quantum dots at a frame rate of 250 Hz with single photon sensitivity. Under these conditions, our approach can determine ON and OFF power-law exponents with a precision of 3% from a comparison to numerical simulations, even for shot-noise-dominated emission signals with an average intensity below 1 photon per frame and per quantum dot. These capabilities pave the way for the unbiased, threshold-free determination of blinking power-law exponents at the micro-second ti...

  19. Determination of susceptibility and specific heat critical exponents for weak itinerant-electron ferromagnets from vibrating reed experiments

    Science.gov (United States)

    Balakrishnan, K.; Kaul, S. N.

    2002-04-01

    We report the observation of a linear relationship between the magnetic contribution to Young's modulus, ΔE/E0, and inverse magnetic susceptibility χ-1 for amorphous weak itinerant-electron ferromagnets Fe90Zr10 and Fe91Zr9 in the asymptotic critical region near the ferromagnetic-paramagnetic phase transition. The proportionality ΔE(T)/E0~χ-1(T) is shown to provide as accurate a means of determining the asymptotic critical exponent γ and the leading ``correction-to-scaling'' amplitudes for susceptibilty from the ΔE/E0 data as a direct measurement of magnetic susceptibilty does. Similarly, the well-known relation between the magnetic contributions to sound velocity and specific heat is fully exploited to extract accurate estimates for the universal critical amplitude ratio A+/A- and the asymptotic critical exponents α+/- for the specific heat from the sound velocity data. The presently determined values of α+/- and γ, together with the reported value for spontaneous magnetization critical exponent β, not only obey the scaling equalities α+=α- and α+2β+γ=2 but also assert that the atomic magnetic moments in the alloys in question interact with one another through an attractive interaction which decays faster than 1/r5 with the interatomic spacing, r.

  20. Autocorrelation analysis for the unbiased determination of power-law exponents in single-quantum-dot blinking.

    Science.gov (United States)

    Houel, Julien; Doan, Quang T; Cajgfinger, Thomas; Ledoux, Gilles; Amans, David; Aubret, Antoine; Dominjon, Agnès; Ferriol, Sylvain; Barbier, Rémi; Nasilowski, Michel; Lhuillier, Emmanuel; Dubertret, Benoît; Dujardin, Christophe; Kulzer, Florian

    2015-01-27

    We present an unbiased and robust analysis method for power-law blinking statistics in the photoluminescence of single nanoemitters, allowing us to extract both the bright- and dark-state power-law exponents from the emitters' intensity autocorrelation functions. As opposed to the widely used threshold method, our technique therefore does not require discriminating the emission levels of bright and dark states in the experimental intensity timetraces. We rely on the simultaneous recording of 450 emission timetraces of single CdSe/CdS core/shell quantum dots at a frame rate of 250 Hz with single photon sensitivity. Under these conditions, our approach can determine ON and OFF power-law exponents with a precision of 3% from a comparison to numerical simulations, even for shot-noise-dominated emission signals with an average intensity below 1 photon per frame and per quantum dot. These capabilities pave the way for the unbiased, threshold-free determination of blinking power-law exponents at the microsecond time scale.

  1. Lyapunov exponent as a metric for assessing the dynamic content and predictability of large-eddy simulations

    Science.gov (United States)

    Nastac, Gabriel; Labahn, Jeffrey W.; Magri, Luca; Ihme, Matthias

    2017-09-01

    Metrics used to assess the quality of large-eddy simulations commonly rely on a statistical assessment of the solution. While these metrics are valuable, a dynamic measure is desirable to further characterize the ability of a numerical simulation for capturing dynamic processes inherent in turbulent flows. To address this issue, a dynamic metric based on the Lyapunov exponent is proposed which assesses the growth rate of the solution separation. This metric is applied to two turbulent flow configurations: forced homogeneous isotropic turbulence and a turbulent jet diffusion flame. First, it is shown that, despite the direct numerical simulation (DNS) and large-eddy simulation (LES) being high-dimensional dynamical systems with O (107) degrees of freedom, the separation growth rate qualitatively behaves like a lower-dimensional dynamical system, in which the dimension of the Lyapunov system is substantially smaller than the discretized dynamical system. Second, a grid refinement analysis of each configuration demonstrates that as the LES filter width approaches the smallest scales of the system the Lyapunov exponent asymptotically approaches a plateau. Third, a small perturbation is superimposed onto the initial conditions of each configuration, and the Lyapunov exponent is used to estimate the time required for divergence, thereby providing a direct assessment of the predictability time of simulations. By comparing inert and reacting flows, it is shown that combustion increases the predictability of the turbulent simulation as a result of the dilatation and increased viscosity by heat release. The predictability time is found to scale with the integral time scale in both the reacting and inert jet flows. Fourth, an analysis of the local Lyapunov exponent is performed to demonstrate that this metric can also determine flow-dependent properties, such as regions that are sensitive to small perturbations or conditions of large turbulence within the flow field. Finally

  2. Power spectral density and scaling exponent of high frequency global solar radiation sequences

    Science.gov (United States)

    Calif, Rudy; Schmitt, François G.; Huang, Yongxiang

    2013-04-01

    invariance: Iq(f) ~ f-?(q) , ?(q) is the scaling exponent. This allows to characterize the scaling behavior of a process: fractal or multifractal with intermittent properties. For q = 2, the Hilbert spectrum is defined. In this work, The data are collected at the University site of Guadeloupe, an island in the West Indies, located at 16°15 N latitude 60°30 W longitude. Our measurements sampled at 1 Hz were performed during one year period. The analyzed data present a power spectral density E(f) displaying a power law of the form E(f) ~ f-β with 1.6 ˜ β ˜ 2.2 for frequencies f ˜ 0.1 Hz, corresponding to time scales T × 10 s. Furthermore, global solar radiation data possesses multifractal properties. For comparison, other multifractal analysis techniques such as structure functions, MDFA, wavelet leaders are also used. This preliminary work set the basis for further investigation dedicated to simulate and forecast a sequence of solar energy fluctuation under different meteorological conditions, in the multifractal framework.

  3. Job loss and broken partnerships: do the number of stressful life events influence the risk of ischemic heart disease in men?

    DEFF Research Database (Denmark)

    Kriegbaum, Margit; Christensen, Ulla; Lund, Rikke

    2008-01-01

    included mother's marital status and father's occupation at birth, body mass index at 18 years, and own educational attainment as covariates. RESULTS: We found that only broken partnerships were associated with IHD (1.28 95% confidence interval 1.02-1.58) and the subdiagnoses of other IHD (1.37 95......% confidence interval 1.02-1.85). We found no indication of dose-response relationship between number of events and risk of IHD. CONCLUSION: In this study of middle-aged men, we found only weak support for the effect of psychosocial stress on IHD measured with register based life events; we found that IHD...... was associated with broken partnerships but not with job loss. We did not find that the risk of incident IHD varied with the number of these stressful life events....

  4. Coping strategies, drinking motives, and stressful life events among middle adolescents: associations with emotional and behavioral problems and with academic functioning.

    Science.gov (United States)

    Windle, M; Windle, R C

    1996-11-01

    A sample of 733 middle adolescents was used to study interrelations among coping strategies, drinking motives, stressful life events (major, daily positive, and daily negative), emotional and behavioral problems, and academic functioning. A main-effects (vs. stress-buffering) model was supported. Some predictors (e.g., task-oriented coping, major stressful events) were general in their predictive relations to the outcome variables, whereas others were highly specific (e.g., emotion-focused coping predicting depressed affect). Overall, the predictors accounted for 22-53% of the variance in regression equations. Positive daily events predicted higher levels of alcohol use, alcohol problems, and delinquent activity; as well as higher academic performance and lower levels of depressed affect.

  5. Depression, Stressful Life Events, and the Impact of Variation in the Serotonin Transporter: Findings from the National Longitudinal Study of Adolescent to Adult Health (Add Health.

    Directory of Open Access Journals (Sweden)

    Brett C Haberstick

    Full Text Available The low transcriptionally efficient short-allele of the 5HTTLPR serotonin transporter polymorphism has been implicated to moderate the relationship between the experience of stressful life events (SLEs and depression. Despite numerous attempts at replicating this observation, results remain inconclusive.We examined this relationship in young-adult Non-Hispanic white males and females between the ages of 22 and 26 (n = 4724 participating in the National Longitudinal Study of Adolescent to Adult Health (Add Health with follow-up information every six years since 1995.Linear and logistic regression models, corrected for multiple testing, indicated that carriers of one or more of the S-alleles were more sensitive to stress than those with two L-alleles and at a higher risk for depression. This relationship behaved in a dose-response manner such that the risk for depression was greatest among those who reported experiencing higher numbers of SLEs. In post-hoc analyses we were not able to replicate an interaction effect for suicide ideation but did find suggestive evidence that the effects of SLEs and 5HTTLPR on suicide ideation differed for males and females. There were no effects of childhood maltreatment.Our results provide partial support for the original hypothesis that 5-HTTLPR genotype interacts with the experience of stressful life events in the etiology of depression during young adulthood. However, even with this large sample, and a carefully constructed a priori analysis plan, the results were still not definitive. For the purposes of replication, characterizing the 5HTTLPR in other large data sets with extensive environmental and depression measures is needed.

  6. Assessing the interplay of childhood adversities with more recent stressful life events and conditions in predicting panic pathology among adults from the general population.

    Science.gov (United States)

    Asselmann, E; Stender, J; Grabe, H J; König, J; Schmidt, C O; Hamm, A O; Pané-Farré, C A

    2018-01-01

    Although research suggests that (a) childhood adversities and more recent stressful life events/conditions are risk factors for panic pathology and that (b) early life stress increases vulnerability to later psychopathology, it remains unclear whether childhood adversities amplify the association between more recent stressful life events/conditions and panic pathology. Data were derived from a general population sample (Study of Health in Pomerania, SHIP). Lifetime panic pathology was assessed with the Munich Composite International Diagnostic Interview (M-CIDI). Childhood adversities (emotional, physical and sexual abuse; emotional and physical neglect) were assessed with the Childhood Trauma Questionnaire (CTQ). More recent separation/loss events and long-lasting stressful conditions were assessed with the Stralsund Life Event List (SEL). Individuals with lifetime panic pathology (fearful spell, panic attack or panic disorder, N = 286) were compared to controls without any psychopathology (N = 286, matched for sex and age). Conditional logistic regressions revealed that childhood adversities as well as more recent separation/loss events and long-lasting stressful conditions were associated with panic pathology (OR 1.1-2.5). Moreover, more recent separation/loss events - but not long-lasting stressful conditions - interacted statistically with each of the examined childhood adversities except for sexual abuse in predicting panic pathology (OR 1.1-1.3). That is, separation/loss events were associated more strongly with panic pathology among individuals with higher childhood adversities. Data were assessed retrospectively and might be subject to recall biases. Findings suggest that early childhood adversities amplify the risk of developing panic pathology after experiencing separation or loss events. Copyright © 2017. Published by Elsevier B.V.

  7. Life stress as a determinant of emotional well-being: development and validation of a Spanish-Language Checklist of Stressful Life Events.

    Science.gov (United States)

    Morote Rios, Roxanna; Hjemdal, Odin; Martinez Uribe, Patricia; Corveleyn, Jozef

    2014-01-01

    Objectives: To develop a screening instrument for investigating the prevalence and impact of stressful life events in Spanish-speaking Peruvian adults. Background: Researchers have demonstrated the causal connection between life stress and psychosocial and physical complaints. The need for contextually relevant and updated instruments has been also addressed. Methods: A sequential exploratory design combined qualitative and quantitative information from two studies: first, the content validity of 20 severe stressors (N = 46); then, a criterion-related validity process with affective symptoms as criteria (Hopkins Symptom Checklist (HSCL-25), N = 844). Results: 93% of the participants reported one to eight life events (X = 3.93, Mdn = 3, SD = 7.77). Events increase significantly until 60 years of age (Mdn = 6). Adults born in inland regions (Mdn = 4) or with secondary or technical education (Mdn = 5) reported significantly more stressors than participants born in Lima or with higher education. There are no differences by gender. Four-step hierarchical models showed that life stress is the best unique predictor (β) of HSCL anxiety, depression and general distress (p three criteria (p < .01, p < .001); lower education and unemployment are significant unique predictors of general distress and depression (p < .01; p < .05). Previously, the two-factor structure of the HSCL-25 was verified (Satorra-Bentler chi-square, root-mean-square error of approximation = 0.059; standardized root-mean-square residual = 0.055). Conclusion: The Spanish-Language Checklist of Stressful Life Events is a valid instrument to identify adults with significant levels of life stress and possible risk for mental and physical health (clinical utility).

  8. Self rating of health is associated with stressful life events, social support and residency in East and West Berlin shortly after the fall of the wall.

    Science.gov (United States)

    Hillen, T; Schaub, R; Hiestermann, A; Kirschner, W; Robra, B P

    2000-08-01

    To compare the health status and factors influencing the health of populations that had previously lived under different political systems. Cross sectional health and social survey using postal interviews. The relation between self reported health and psychosocial factors (stressful life events, social support, education, health promoting life style and health endangering behaviour) was investigated. To determine East-West differences a logistic regression model including interaction terms was fitted. East and West Berlin shortly after reunification 1991. Representative sample of 4430 Berlin residents aged 18 years and over (response rate 63%). Of all respondents, 15.4% rated their health as unsatisfactory. Residents of East Berlin rated their health more frequently as unsatisfactory than residents of West Berlin (Or(age adjusted)= 1.29, 95%CI 1.08, 1.52), these differences occurred predominantly in the over 60 years age group. Logistic regression showed significant independent effects of stressful life events, social support, education, and health promoting life style on self rated health. The effects of education and health promoting life style were observed to be more pronounced in the western part of Berlin. Old age and female sex showed a stronger association with unsatisfactory health status in the eastern part of Berlin. For subjects aged over 60 years there was evidence that living in the former East Berlin had an adverse effect on health compared with West Berlin. The impact of education and a health promoting lifestyle on self rated health seemed to be weaker in a former socialist society compared with that of a Western democracy. This study supports an "additive model" rather than a "buffering model" in explaining the effects of psychosocial factors on health.

  9. A method for extracting the scaling exponents of a self-affine, non-Gaussian process from a finite length timeseries.

    Science.gov (United States)

    Kiyani, K.; Chapman, S. C.; Hnat, B.

    2006-12-01

    We address the generic problem of extracting the scaling exponents of a stationary, self-affine process realised by a timeseries of finite length, where information about the process is not known a priori. Estimating the scaling exponents relies upon estimating the moments, or more typically structure functions, of the probability density of the differenced timeseries. If the probability density is heavy tailed, outliers strongly influence the scaling behaviour of the moments. From an operational point of view, we wish to recover the scaling exponents of the underlying process by excluding a minimal population of these outliers. We test these ideas on a synthetically generated symmetric alpha-stable Levy process and show that the Levy exponent is recovered in up to the 6th order moment after only ~0.1-0.5% of the data are excluded. The scaling properties of the excluded outliers can then be tested to provide additional information about the system.

  10. Critical exponents for a transition from integrability to non-integrability via localization of invariant tori in the Hamiltonian system

    Energy Technology Data Exchange (ETDEWEB)

    Leonel, Edson D; De Oliveira, Juliano A; Saif, Farhan, E-mail: edleonel@rc.unesp.br [Departamento de EstatIstica, Matematica Aplicada e Computacao, UNESP-Univ. Estadual Paulista, Av. 24A, 1515, Bela Vista, 13506-900 Rio Claro, Sao Paulo (Brazil)

    2011-07-29

    Critical exponents that describe a transition from integrability to non-integrability in a two-dimensional, nonlinear and area-preserving map are obtained via localization of the first invariant spanning curve (invariant tori) in the phase space. In a general class of systems, the position of the first invariant tori is estimated by reducing the mapping of the system to the standard mapping where a transition takes place from local to global chaos. The phase space of the mapping shows a large chaotic sea surrounding periodic islands and limited by a set of invariant tori whose position of the first of them depends on the control parameters. The formalism leads us to obtain analytically critical exponents that describe the behaviour of the average variable (action) along the chaotic sea. The result is compared to several models in the literature confirming the approach is of large interest. The formalism used is general and the procedure can be extended to many other different systems. (fast track communication)

  11. Assessment of Effects of a Delay Block and a Nonlinear Block in Systems with Chaotic Behavior Using Lyapunov Exponents

    Directory of Open Access Journals (Sweden)

    Pablo César Rodríguez Gómez

    2017-05-01

    Full Text Available Context: Because feedback systems are very common and widely used, studies of the structural characteristics under which chaotic behavior is generated have been developed. These can be separated into a nonlinear system and a linear system at least of the third order. Methods such as the descriptive function have been used for analysis. Method: A feedback system is proposed comprising a linear system, a nonlinear system and a delay block, in order to assess his behavior using Lyapunov exponents. It is evaluated with three different linear systems, different delay values and different values for parameters of nonlinear characteristic, aiming to reach chaotic behavior. Results: One hundred experiments were carried out for each of the three linear systems, by changing the value of some parameters, assessing their influence on the dynamics of the system. Contour plots that relate these parameters to the Largest Lyapunov exponent were obtained and analyzed. Conclusions: In spite non-linearity is a condition for the existence of chaos, this does not imply that any nonlinear characteristic generates a chaotic system, it is reflected by the contour plots showing the transitions between chaotic and no chaotic behavior of the feedback system. Language: English

  12. The Interacting Effect of the BDNF Val66Met Polymorphism and Stressful Life Events on Adolescent Depression Is Not an Artifact of Gene-Environment Correlation: Evidence from a Longitudinal Twin Study

    Science.gov (United States)

    Chen, Jie; Li, Xinying; McGue, Matt

    2013-01-01

    Background: Confounding introduced by gene-environment correlation (rGE) may prevent one from observing a true gene-environment interaction (G × E) effect on psychopathology. The present study investigated the interacting effect of the BDNF Val66Met polymorphism and stressful life events (SLEs) on adolescent depression while controlling for the…

  13. Hurst exponent used as a tool to differentiate between magmatic and fluid-induced processes as reflected in crystal geochemistry

    Science.gov (United States)

    Domonik, A.; Słaby, E.; Śmigielski, M.

    2012-04-01

    A self-similarity parameter, the Hurst exponent (H) (called also roughness exponent) has been used to show the long-range dependence of element behaviour during the processes. The H value ranges between 0 and 1; a value of 0.5 indicates a random distribution indistinguishable from noise. For values greater or less than 0.5, the system shows non-linear dynamics. H 0.5 corresponds to increasing persistence (less chaotic). Such persistence is characterized as an effect of a long-term memory, and thus by a large degree of positive correlation. In theory, the preceding data constantly affect the next in the whole temporal series. Applied to chaotic dynamics, the system shows a subtle sensitivity to initial conditions. The process can show some degree of chaos, due to local variations, but generally, the trend preserves its persistent character through time. If the exponent value is low, the process shows frequent and sudden reversals e.g. the trends of such a process show mutual negative correlation of the succeding values in the data series. Thus, the system can be described as having a high degree of deterministic chaos. Alkali feldspar megacrysts grown from mixed magmas and recrystallized due to interaction with fluids have been selected for the study (Słaby et al., 2011). Hurst exponent variability has been calculated within some primary-magmatic and secondary-recrystallized crystal domains for some elements redistributed by crystal fluid interaction. Based on the Hurst exponent value two different processes can easily be recognized. In the core of the megacrysts the element distribution can be ascribed to magmatic growth. By contrast, the marginal zones can relate to inferred late crystal-fluid interactions. Both processes are deterministic, not random. The spatial distribution of elements in the crystal margins is irregular, with high-H values identifying the process as persistent. The trace element distributions in feldspar cores are almost homogeneous and only

  14. Time-varying associations of suicide with deployments, mental health conditions, and stressful life events among current and former US military personnel: a retrospective multivariate analysis.

    Science.gov (United States)

    Shen, Yu-Chu; Cunha, Jesse M; Williams, Thomas V

    2016-11-01

    US military suicides have increased substantially over the past decade and currently account for almost 20% of all military deaths. We investigated the associations of a comprehensive set of time-varying risk factors with suicides among current and former military service members. We did a retrospective multivariate analysis of all US military personnel between 2001 and 2011 (n=110 035 573 person-quarter-years, representing 3 795 823 service members). Outcome was death by suicide, either during service or post-separation. We used Cox proportional hazard models at the person-quarter level to examine associations of deployment, mental disorders, history of unlawful activity, stressful life events, and other demographic and service factors with death by suicide. The strongest predictors of death by suicide were current and past diagnoses of self-inflicted injuries, major depression, bipolar disorder, substance use disorder, and other mental health conditions (compared with service members with no history of diagnoses, the hazard ratio [HR] ranged from 1·4 [95% CI 1·14-1·72] to 8·34 [6·71-10·37]). Compared with service members who were never deployed, hazard rates of suicide (which represent the probability of death by suicide in a specific quarter given that the individual was alive in the previous quarter) were lower among the currently deployed (HR 0·50, 95% CI 0·40-0·61) but significantly higher in the quarters following first deployment (HR 1·51 [1·17-1·96] if deployed in the previous three quarters; 1·14 [1·06-1·23] if deployed four or more quarters ago). The hazard rate of suicide increased within the first year of separation from the military (HR 2·49, 95% CI 2·12-2·91), and remained high for those who had separated from the military 6 or more years ago (HR 1·63, 1·45-1·82). The increased hazard rate of death by suicide for military personnel varies by time since exposure to deployment, mental health diagnoses, and other stressful

  15. Les rites de la mort à Bornéo : séparation ou renaissance ? Actualité de Robert Hertz Death Rites in Borneo: Separation or Rebirth? Robert Hertz’ Legacy

    Directory of Open Access Journals (Sweden)

    Pascal Couderc

    2012-12-01

    Full Text Available La publication récente par le Borneo Research Council d’un ouvrage collectif sur la mort fournit l’occasion de réévaluer l’apport de Robert Hertz à la compréhension des rites funéraires à Bornéo. Si la traduction en anglais, dans les années 1960, de l’essai de Hertz sur la représentation collective de la mort avait consacré, grâce notamment aux travaux de Peter Metcalf sur les Berawan, la puissance du modèle analytique hertzien, ce nouvel ouvrage semble signaler que le moment de la célébration finale est venu, où les héritiers se libèrent de l’emprise spirituelle du défunt. Tout en conservant une grande part de sa valeur comme théorie du deuil, le paradigme transitionnel ou « réactif » de Hertz révèle ses limites, mises ici en lumière par des données ethnographiques encore peu connues ou inédites, qui démontrent, par exemple, l’existence d’une circulation des composantes de la personne par delà l’opposition entre la vie et la mort, ou encore l’influence directe des secondes funérailles sur la renaissance des défunts. Cet article aborde le dépassement du modèle hertzien en retournant à la lettre de l’essai, dont il met en relief l’intelligence ethnographique et la finesse théorique.The recent publication by the Borneo Research Council of a collection of essays on death provides an opportunity to reassess the heritage of Robert Hertz, whose theory of the double obsequies relies heavily on the ethnography of the Ngaju and other Borneo peoples. The translation of Hertz’s essay on the collective representation of death in the 1960s, prompting in particular Peter Metcalf’s work on the Berawan, has consecrated the explanatory power of Hertz’s model. With this new book, however, time seems to have come for the final celebration that marks the heirs’ liberation from the deceased’s spiritual influence. While still largely valid as a general theory of mourning, Hertz’s paradigm of

  16. Application of AERONET Single Scattering Albedo and Absorption Angstrom Exponent to Classify Dominant Aerosol Types during DRAGON Campaigns

    Science.gov (United States)

    Giles, D. M.; Holben, B. N.; Eck, T. F.; Schafer, J.; Crawford, J. H.; Kim, J.; Sano, I.; Liew, S.; Salinas Cortijo, S. V.; Chew, B. N.; Lim, H.; Smirnov, A.; Sorokin, M.; Kenny, P.; Slutsker, I.

    2013-12-01

    Aerosols can have major implications on human health by inducing respiratory diseases due to inhalation of fine particles from biomass burning smoke or industrial pollution and on radiative forcing whereby the presence of absorbing aerosol particles (e.g., black carbon) increases atmospheric heating. Aerosol classification techniques have utilized aerosol loading and aerosol properties derived from multi-spectral and multi-angle observations by ground-based (e.g., AERONET) and satellite instrumentation (e.g., MISR). Aerosol Robotic Network (AERONET) data have been utilized to determine aerosol types by implementing various combinations of measured aerosol optical depth or retrieved size and absorption aerosol properties (e.g., Gobbi et al., 2007; Russell et al., 2010). Giles et al. [2012] showed single scattering albedo (SSA) relationship with extinction Angstrom exponent (EAE) can provide an estimate of the general classification of dominant aerosol types (i.e., desert dust, urban/industrial pollution, biomass burning smoke, and mixtures) based on data from ~20 AERONET sites located in known aerosol source regions. In addition, the absorption Angstrom exponent relationship with EAE can provide an indication of the dominant absorbing aerosol type such as dust, black carbon, brown carbon, or mixtures of them. These classification techniques are applied to the AERONET Level 2.0 quality assured data sets collected during Distributed Regional Aerosol Gridded Observational Network (DRAGON) campaigns in Maryland (USA), Japan, South Korea, Singapore, Penang (Malaysia), and California (USA). An analysis of aerosol type classification for DRAGON sites is performed as well as an assessment of the spatial variability of the aerosol types for selected DRAGON campaigns. Giles, D. M., B. N. Holben, T. F. Eck, A. Sinyuk, A. Smirnov, I. Slutsker, R. R. Dickerson, A. M. Thompson, and J. S. Schafer (2012), An analysis of AERONET aerosol absorption properties and classifications

  17. Stressful life events, ethnic identity, historical trauma, and participation in cultural activities: Associations with smoking behaviors among American Indian adolescents in California.

    Science.gov (United States)

    Soto, Claradina; Baezconde-Garbanati, Lourdes; Schwartz, Seth J; Unger, Jennifer B

    2015-11-01

    American Indian (AI) adolescents have the highest prevalence of commercial tobacco use of any ethnic group in the United States. This study examines ethnic identity (EI), participation in cultural activities, and stressful life events (SLEs) as correlates of smoking and examines historical trauma (HT) as a mediator of these associations. California AI youth (N = 969, ages 13-19, recruited from 49 tribal youth organizations and cultural activities in urban and reservation areas in California) completed a tobacco survey. Structural equation modeling was used to test a model examining HT as a potential mediator of the associations of EI, participation in cultural activities, and SLEs with cigarette smoking. Model fit was adequate. EI, participation in cultural activities, and SLEs predicted HT. HT mediated the associations of participation in cultural activities and SLEs with past-month smoking. Stronger EI predicted greater past-month smoking and this effect was mediated by greater HT. The direct effects from HT to both smoking outcomes were positive and the direct effect from EI to past-month smoking was negative. HT is a risk factor for cigarette smoking both directly and in mediating the links of EI, cultural activities, and SLEs. More efforts are needed to help AI youth to process these thoughts and empower themselves to contribute to their own lives and those of their families and communities without resorting to unhealthy addictive behaviors such as commercial tobacco use. Published by Elsevier Ltd.

  18. Shame amplifies the association between stressful life events and paranoia amongst young adults using mental health services: Implications for understanding risk and psychological resilience.

    Science.gov (United States)

    Johnson, Judith; Jones, Christopher; Lin, Ashleigh; Wood, Stephen; Heinze, Kareen; Jackson, Christopher

    2014-12-15

    Shame is associated with a range of psychological disorders, and is a trans-diagnostic moderator of the association between stressors and symptoms of disorder. However, research has yet to investigate shame in relation to specific psychotic symptoms in clinical groups. In order to address this, the present study investigated shame in young adults with mental health problems, to test whether shame was i) directly associated with paranoia, a prevalent psychotic symptom, and ii) a moderator of the association between stress and paranoia. Sixty participants completed measures of stressful events, paranoia, shame, depression and anxiety. Results from a cross-sectional regression analysis suggested that shame was associated with paranoia after the stressful life event measure was entered into the model, and shame moderated the association between stress and paranoia. For individuals scoring high on shame, shame amplified the association between stress and paranoia, but for low-shame individuals, the association between stress and paranoia was non-significant. These findings suggest that high levels of shame could confer vulnerability for paranoia amongst clinical groups, and that resistance to experiencing shame could be a marker of resilience. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  19. What a difference a year makes: comparing relationships between stressful life events, mood and life satisfaction among older adults, and their working-age counterparts.

    Science.gov (United States)

    Hannaford, Elizabeth; Moore, Fhionna; Macleod, Fiona J

    2017-10-11

    Stressful life events (SLEs) have been linked to depression, anxiety, and reduced life satisfaction. The inoculation hypothesis of aging suggests older adults may be less vulnerable to poor psychological outcomes following SLEs than working-age adults. The current study compared relationships between SLEs, mood and life satisfaction among older adults (65+), and adults aged 50-64, and investigated whether group identification and loneliness moderate these relationships. A community-based sample of 121 Scottish participants responded to measures of SLEs (modified Social Readjustment Rating Scale), symptoms of depression and anxiety (Hospital Anxiety and Depression Scale), life satisfaction (Life Satisfaction Index A), group identification (Group Identification Scale), and loneliness (UCLA Loneliness Scale). In the 50-64 age group, the number of SLEs was significantly associated with greater symptoms of depression and anxiety, and reduced life satisfaction. Group identification and loneliness did not moderate these relationships. There were no significant relationships in the older adult group. The finding of relationships in working-age, but not older adults, supports the inoculation hypothesis of aging. Further research to better understand changes across the lifespan, and inter-relationships with related variables, would be valuable from both theoretical and clinical perspectives.

  20. Attachment security and recent stressful life events predict oxytocin levels: a pilot study of pregnant women with high levels of cumulative psychosocial adversity.

    Science.gov (United States)

    Samuel, Simcha; Hayton, Barbara; Gold, Ian; Feeley, Nancy; Carter, C Sue; Zelkowitz, Phyllis

    2015-01-01

    Recent reports indicate that prenatal levels of the neuropeptide oxytocin (OT) are inversely related to depressive symptomatology and positively associated with more optimal interactive behaviors in mothers with high levels of cumulative psychosocial adversity (CPA). In the present pilot study, we aimed to identify factors associated with high versus low levels of OT in pregnant women with high levels of CPA. We hypothesized that insecurely attached women, and those who recently experienced stressful life events (SLE), would have lower levels of prenatal OT. Thirty pregnant women with mood and anxiety disorders and high levels of CPA were recruited from the perinatal mental health service of a general hospital. Participants completed self-report measures of psychosocial stress and adult attachment style, and blood was then drawn to assess OT. Lower OT levels were found among those who were insecurely attached, and among those who experienced SLE within the last year. In a multiple linear regression, both attachment security and SLE significantly contributed to a model of prenatal OT levels. These individual difference factors explained 38% of the variance in prenatal OT, which may in turn predict poorer maternal mental health and caregiving outcomes during the postpartum period.

  1. A population-based longitudinal study of recent stressful life events as risk factors for suicidal behavior in major depressive disorder.

    Science.gov (United States)

    Wang, Yunqiao; Sareen, Jitender; Afifi, Tracie O; Bolton, Shay-Lee; Johnson, Edward A; Bolton, James M

    2015-01-01

    The purpose of this study is to investigate whether the type and number of stressful life events (SLEs) will be associated with suicidal behavior in a 3-year follow-up period in persons with major depressive disorder (MDD). Data came from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a nationally representative longitudinal survey of mental health in non-institutionalized adults in the United States. The survey consisted of two waves: Wave 1 (2001--2002) and Wave 2 (2004-2005), n = 34,653. Twelve past-year SLEs were assessed at baseline. These SLEs were categorized into the following groups based on previous research: Loss or victimization; Relationship, friendship, or interpersonal stress; Financial stress; and Legal problems. Only respondents with MDD at Wave 1 were included (n = 6,004). Several SLEs were strongly associated with suicide attempts, among which, "serious problems with neighbor, friend, or relative" (adjusted odds ratio [AOR] = 2.21; 95% confidence interval [95% CI]: 1.41, 3.45) and "major financial crisis, bankruptcy, or unable to pay bills" (AOR = 2.31; 95% CI: 1.45, 3.66) were the most robust predictors of suicide attempts even after adjusting for sociodemographic variables and any anxiety, substance use, or personality disorder. People with MDD who had been exposed to certain SLEs are at elevated risk for future suicide attempts, even after accounting for the demographic factors and psychiatric comorbidity.

  2. Gender Differences of Stressful Life Events, Coping Style, Symptom Severity, and Health-Related Quality of Life in Patients With Panic Disorder.

    Science.gov (United States)

    Kim, Ji Eun; Song, In Han; Lee, Sang-Hyuk

    2017-09-01

    Although affective disorders have been known to have sex differences in the associated clinical characteristics and quality of life (QOL), sex differences among patients with panic disorder (PD) have remained relatively unexplored in Korea. We examined the sex differences in different types of stressful life events (SLEs), coping styles, symptom severity, and health-related QOL (HRQOL) in patients with PD. Data from 291 female and 254 male participants diagnosed with PD were analyzed using a structured clinical interview following the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition criteria. Females with PD reported more SLEs including separation issues, physical illness or disability, and pregnancy-related problems than males. They also reported lower levels of confrontation and help-seeking coping strategies and higher levels of agoraphobia in symptom severity than males. The HRQOL of females with PD was significantly lower than male in physical functioning of HRQOL. This study suggests that the patient's sex is relevant to the assessment and treatment of PD.

  3. Differences in frontal and limbic brain activation in a small sample of monozygotic twin pairs discordant for severe stressful life events

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    Detre A. Godinez

    2016-12-01

    Full Text Available Monozygotic twin pairs provide a valuable opportunity to control for genetic and shared environmental influences while studying the effects of nonshared environmental influences. The question we address with this design is whether monozygotic twins selected for discordance in exposure to severe stressful life events during development (before age 18 demonstrate differences in brain activation during performance of an emotional word-face Stroop task. In this study, functional magnetic resonance imaging was used to assess brain activation in eighteen young adult twins who were discordant in exposure to severe stress such that one twin had two or more severe events compared to their control co-twin who had no severe events. Twins who experienced higher levels of stress during development, compared to their control co-twins with lower stress, exhibited significant clusters of greater activation in the ventrolateral and medial prefrontal cortex, basal ganglia, and limbic regions. The control co-twins showed only the more typical recruitment of frontoparietal regions thought to be important for executive control of attention and maintenance of task goals. Behavioral performance was not significantly different between twins within pairs, suggesting the twins with stress recruited additional neural resources associated with affective processing and updating working memory when performing at the same level. This study provides a powerful glimpse at the potential effects of stress during development while accounting for shared genetic and environmental influences.

  4. Post-traumatic growth, stressful life events, and relationships with substance use behaviors among alternative high school students: a prospective study.

    Science.gov (United States)

    Arpawong, Thalida E; Sussman, Steve; Milam, Joel E; Unger, Jennifer B; Land, Helen; Sun, Ping; Rohrbach, Louise A

    2015-01-01

    A highly stressful life event (SLE) can elicit positive psychosocial growth, referred to as post-traumatic growth (PTG) among youth. We examined PTG and the number of SLEs for their influence on substance use behaviours among a sample of older, diverse alternative high school students participating in a drug prevention programme (n=564; mean age=16.8; 49% female; 65% Hispanic). Surveys assessed PTG, SLEs and substance use behaviours at the two-year follow-up. Multilevel regression models were run to examine the effect of PTG and the number of SLEs on frequency of substance use at the two-year follow-up, controlling for baseline substance use, sociodemographic variables, peer substance use, attrition propensity and treatment group. Greater PTG scores were associated with lower frequencies of alcohol use, getting drunk on alcohol, binge drinking, marijuana use and less substance abuse at the two-year follow-up, but not associated with cigarette or hard drug use. Also, PTG did not moderate the relationship between cumulative number of SLEs and substance use behaviours, rather PTG appears to be protective against negative effects of a single, life-altering SLE. Fostering PTG from a particularly poignant SLE may be useful for prevention programmes targeting alcohol, marijuana and substance abuse behaviours among high-risk youth.

  5. Existence and uniqueness of weak and entropy solutions for homogeneous Neumann boundary-value problems involving variable exponents

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    Bernard K. Bonzi

    2012-01-01

    Full Text Available In this article we study the nonlinear homogeneous Neumann boundary-value problem $$displaylines{ b(u-hbox{div} a(x,abla u=fquad hbox{in } Omegacr a(x,abla u.eta=0 quadhbox{on }partial Omega, }$$ where $Omega$ is a smooth bounded open domain in $mathbb{R}^{N}$, $N geq 3$ and $eta$ the outer unit normal vector on $partialOmega$. We prove the existence and uniqueness of a weak solution for $f in L^{infty}(Omega$ and the existence and uniqueness of an entropy solution for $L^{1}$-data $f$. The functional setting involves Lebesgue and Sobolev spaces with variable exponents.

  6. Triadic closure dynamics explains scaling-exponents for preferential attachment-, degree- and clustering distributions in social multiplex data

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    Klimek, Peter

    2013-01-01

    Social networks exhibit scaling-laws for several structural characteristics, such as the degree distribution, the scaling of the attachment kernel, and the clustering coefficients as a function of node degree. A detailed understanding if and how these scaling laws are inter-related is missing so far, let alone whether they can be understood through a common, dynamical principle. We propose a simple model for stationary network formation and show that the three mentioned scaling relations follow as natural consequences of triadic closure. The validity of the model is tested on multiplex data from a well studied massive multiplayer online game. We find that the three scaling exponents observed in the multiplex data for the friendship, communication and trading networks can simultaneously be explained by the model. These results suggest that triadic closure could be identified as one of the fundamental dynamical principles in social multiplex network formation.

  7. A Different Statistic for the Management of Portfolios - the Hurst Exponent: Persistent, Antipersistent or Random Time Series?

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    Ana-Maria CALOMFIR (METESCU

    2015-12-01

    Full Text Available In recent years, research in the capital markets and management of portfolios has been producing more questions than it has been answering: the need for a new paradigm or a new way of looking at things has become more and more concludent. The existing and classical view of capital markets, based on efficient market hypothesis, has a definite theory for the last six decades, but it is still not capable of significantly increase the understanding of how capital markets function. The purpose of this article is to theoretically describe a less used statistic coefficient, having a vast area of applicability due to its robustness, and which can easily divide the random series from a non-random series, even if the random series is non-Gaussian: the Hurst exponent.

  8. Critical exponents and irreversibility lines of La0.9Sr0.1CoO3 single crystal

    Science.gov (United States)

    Khan, N.; Midya, A.; Mandal, P.; Prabhakaran, D.

    2013-05-01

    We have studied the dynamic and static critical behavior of spin glass transition in insulating La0.9Sr0.1CoO3 single crystal by ac susceptibility and dc magnetization measurements in the vicinity of its freezing temperature (Tf). The dynamic scaling analysis of the frequency dependence of ac susceptibility data yields the characteristic time constant τ0=1.6(9)×10-12 s, the dynamic critical exponent zν=9.5(2), and a frequency dependence factor K =ΔTf/Tf(Δlogf)=0.017, indicating that the sample enters into a canonical spin-glass phase below Tf = 34.8(2) K. The scaling analysis of non-linear magnetization in the vicinity of Tf through the static scaling hypothesis yields critical exponents β = 0.89(1) and γ = 2.9(1), which match well with that observed for well known three-dimensional (3D) Heisenberg spin glasses. From the longitudinal component of zero-field-cooled and field-cooled magnetization measurement, we have constructed the H-T phase diagram which represents the field evolution of two characteristic temperatures: the upper one, Tw(H), indicates the onset of spin freezing in a uniform external field H, while the lower one, Ts(H), marks the onset of strong irreversibility of the frozen state. The low field Ts(H) follows the critical line suggested by d'Almeida-Thouless model for canonical spin glass, whereas the Tw(H) exhibits a re-entrant behavior with a maximum in the Tw(H) at a nonzero field above which it follows the Gabay-Toulouse (GT) critical line which is a characteristic of Heisenberg spin glass. The reentrant behavior of the GT line resembles that predicted theoretically for n-component vector spin glasses in the presence of a uniaxial anisotropy field.

  9. Sensitivity of Particle Extinction and Backscattering Calculation from Mie-Raman Lidar Measurements to the Choice of Ångström Exponent

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    Suvorina Anastasia

    2016-01-01

    Full Text Available Vibrational Raman scattering from nitrogen is commonly used in Mie-Raman lidars for evaluation of particle backscattering (β and extinction (α coefficients. However, vibrational scattering is characterized by significant frequency shift of the Raman component, so for the calculation of α and β the assumption about the extinction Ångström exponent is needed. Simulation results presented in this study demonstrate that ambiguity in the choice of this exponent can be the significant source of uncertainty in the calculation of backscattering coefficients when optically thick aerosol layers are considered. Examples of lidar measurements and optical data calculated for different values of Ångström exponent are given.

  10. Stressful life events, perceived stress, and 12-month course of geriatric depression: direct effects and moderation by the 5-HTTLPR and COMT Val158Met polymorphisms.

    Science.gov (United States)

    Zannas, Anthony S; McQuoid, Douglas R; Steffens, David C; Chrousos, George P; Taylor, Warren D

    2012-07-01

    Although the relation between stressful life events (SLEs) and risk of major depressive disorder is well established, important questions remain about the effects of stress on the course of geriatric depression. Our objectives were (1) to examine how baseline stress and change in stress is associated with course of geriatric depression and (2) to test whether polymorphisms of serotonin transporter (5-HTTLPR) and catechol-O-methyltransferase (COMT Val158Met) genes moderate this relation. Two-hundred and sixteen depressed subjects aged 60 years or older were categorized by remission status (Montgomery-Asberg depression rating scale≤6) at 6 and 12 months. At 6 months, greater baseline numbers of self-reported negative and total SLEs and greater baseline perceived stress severity were associated with lower odds of remission. At 12 months, only baseline perceived stress predicted remission. When we examined change in stress, 12-month decrease in negative SLEs and level of perceived stress were associated with improved odds of 12-month remission. When genotype data were included, COMT Val158Met genotype did not influence these relations. However, when compared with 5-HTTLPR L/L homozygotes, S allele carriers with greater baseline numbers of negative SLEs and with greater decrease in negative SLEs were more likely to remit at 12 months. This study demonstrates that baseline SLEs and perceived stress severity may influence the 12-month course of geriatric depression. Moreover, changes in these stress measures over time correlate with depression outcomes. 5-HTTLPR S carriers appear to be more susceptible to both the effects of enduring stress and the benefit of interval stress reduction.

  11. The structural equation analysis of childhood abuse, adult stressful life events, and temperaments in major depressive disorders and their influence on refractoriness

    Science.gov (United States)

    Toda, Hiroyuki; Inoue, Takeshi; Tsunoda, Tomoya; Nakai, Yukiei; Tanichi, Masaaki; Tanaka, Teppei; Hashimoto, Naoki; Nakato, Yasuya; Nakagawa, Shin; Kitaichi, Yuji; Mitsui, Nobuyuki; Boku, Shuken; Tanabe, Hajime; Nibuya, Masashi; Yoshino, Aihide; Kusumi, Ichiro

    2015-01-01

    Background Previous studies have shown the interaction between heredity and childhood stress or life events on the pathogenesis of a major depressive disorder (MDD). In this study, we tested our hypothesis that childhood abuse, affective temperaments, and adult stressful life events interact and influence the diagnosis of MDD. Patients and methods A total of 170 healthy controls and 98 MDD patients were studied using the following self-administered questionnaire surveys: the Patient Health Questionnaire-9 (PHQ-9), the Life Experiences Survey, the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Autoquestionnaire, and the Child Abuse and Trauma Scale (CATS). The data were analyzed with univariate analysis, multivariable analysis, and structural equation modeling. Results The neglect scores of the CATS indirectly predicted the diagnosis of MDD through cyclothymic and anxious temperament scores of the Temperament Evaluation of the Memphis, Pisa, Paris, and San Diego Autoquestionnaire in the structural equation modeling. Two temperaments – cyclothymic and anxious – directly predicted the diagnosis of MDD. The validity of this result was supported by the results of the stepwise multivariate logistic regression analysis as follows: three factors – neglect, cyclothymic, and anxious temperaments – were significant predictors of MDD. Neglect and the total CATS scores were also predictors of remission vs treatment-resistance in MDD patients independently of depressive symptoms. Limitations The sample size was small for the comparison between the remission and treatment-resistant groups in MDD patients in multivariable analysis. Conclusion This study suggests that childhood abuse, especially neglect, indirectly predicted the diagnosis of MDD through increased affective temperaments. The important role as a mediator of affective temperaments in the effect of childhood abuse on MDD was suggested. PMID:26316754

  12. A genetic variant in 12q13, a possible risk factor for bipolar disorder, is associated with depressive state, accounting for stressful life events.

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    Ayu Shimasaki

    Full Text Available Genome-wide association studies (GWASs have identified a number of susceptibility genes for schizophrenia (SCZ and bipolar disorder (BD. However, the identification of risk genes for major depressive disorder (MDD has been unsuccessful because the etiology of MDD is more influenced by environmental factors; thus, gene-environment (G × E interactions are important, such as interplay with stressful life events (SLEs. We assessed the G×E interactions and main effects of genes targeting depressive symptoms. Using a case-control design, 922 hospital staff members were evaluated for depressive symptoms according to Beck Depressive Inventory (BDI; "depression" and "control" groups were classified by scores of 10 in the BDI test, SLEs, and personality. A total of sixty-three genetic variants were selected on the basis of previous GWASs of MDD, SCZ, and BD as well as candidate-gene (SLC6A4, BDNF, DBH, and FKBP5 studies. Logistic regression analysis revealed a marginally significant interaction (genetic variant × SLE at rs4523957 (P uncorrected = 0.0034 with depression and a significant association of single nucleotide polymorphism identified from evidence of BD GWAS (rs7296288, downstream of DHH at 12q13.1 with depression as the main effect (P uncorrected = 9.4 × 10(-4, P corrected = 0.0424. We also found that SLEs had a larger impact on depression (odds ratio ∼ 3, as reported previously. These results suggest that DHH plays a possible role in depression etiology; however, variants from MDD or SCZ GWAS evidence or candidate genes showed no significant associations or minimal effects of interactions with SLEs on depression.

  13. Possibility between earthquake and explosion seismogram differentiation by discrete stochastic non-Markov processes and local Hurst exponent analysis.

    Science.gov (United States)

    Yulmetyev, R; Gafarov, F; Hänggi, P; Nigmatullin, R; Kayumov, S

    2001-12-01

    The basic scientific point of this paper is to draw the attention of researchers to new possibilities of differentiation of similar signals having different nature. One example of such kinds of signals is presented by seismograms containing recordings of earthquakes (EQ's) and technogenic explosions (TE's). EQ's are among the most dramatic phenomena in nature. We propose here a discrete stochastic model for possible solution of a problem of strong EQ forecasting and differentiation of TE's from the weak EQ's. Theoretical analysis is performed by two independent methods: by using statistical theory of discrete non-Markov stochastic processes [Phys. Rev. E 62, 6178 (2000)] and the local Hurst exponent. The following Earth states have been considered among them: before (Ib) and during (I) strong EQ, during weak EQ (II) and during TE (III), and in a calm state of Earth's core (IV). The estimation of states I, II, and III has been made on the particular examples of Turkey (1999) EQ's, state IV has been taken as an example of Earth's state before underground TE. Time recordings of seismic signals of the first four dynamic orthogonal collective variables, six various planes of phase portrait of four-dimensional phase space of orthogonal variables and the local Hurst exponent have been calculated for the dynamic analysis of states of systems I-IV. The analysis of statistical properties of seismic time series I-IV has been realized with the help of a set of discrete time-dependent functions (time correlation function and first three memory functions), their power spectra, and the first three points in the statistical spectrum of non-Markovity parameters. In all systems studied we have found a bizarre combination of the following spectral characteristics: the fractal frequency spectra adjustable by phenomena of usual and restricted self-organized criticality, spectra of white and color noises and unusual alternation of Markov and non-Markov effects of long-range memory

  14. Trend analysis of aerosol optical thickness and Ångström exponent derived from the global AERONET spectral observations

    Directory of Open Access Journals (Sweden)

    J. Yoon

    2012-06-01

    Full Text Available Regular aerosol observations based on well-calibrated instruments have led to a better understanding of the aerosol radiative budget on Earth. In recent years, these instruments have played an important role in the determination of the increase of anthropogenic aerosols by means of long-term studies. Only few investigations regarding long-term trends of aerosol optical characteristics (e.g. aerosol optical thickness (AOT and Ångström exponent (ÅE have been derived from ground-based observations. This paper aims to derive and discuss linear trends of AOT (440, 675, 870, and 1020 nm and ÅE (440–870 nm using AErosol RObotic NETwork (AERONET level 2.0 spectral observations. Additionally, temporal trends of coarse- and fine-mode dominant AOTs (CdAOT and FdAOT have been estimated by applying an aerosol classification based on accurate ÅE and Ångström exponent difference (ÅED. In order to take into account the fact that cloud disturbance is having a significant influence on the trend analysis of aerosols, we introduce a weighted least squares regression depending on two weights: (1 monthly standard deviation (σt and (2 number of observations per month (nt.

    Temporal increase of FdAOTs (440 nm prevails over newly industrializing countries in East Asia (weighted trends; +6.23% yr−1 at Beijing and active agricultural burning regions in South Africa (+1.89% yr−1 at Mongu. On the other hand, insignificant or negative trends for FdAOTs are detected over Western Europe (+0.25% yr−1 at Avignon and −2.29% yr−1 at Ispra and North America (−0.52% yr−1 for GSFC and −0.01% yr−1 at MD_Science_Center. Over desert regions, both increase and decrease of CdAOTs (+3.37% yr−1 at Solar_Village and −1.18% yr−1 at Ouagadougou are observed depending on meteorological conditions.

  15. Trend analysis of aerosol optical thickness and Ångström exponent derived from the global AERONET spectral observations

    Science.gov (United States)

    Yoon, J.; von Hoyningen-Huene, W.; Kokhanovsky, A. A.; Vountas, M.; Burrows, J. P.

    2012-06-01

    Regular aerosol observations based on well-calibrated instruments have led to a better understanding of the aerosol radiative budget on Earth. In recent years, these instruments have played an important role in the determination of the increase of anthropogenic aerosols by means of long-term studies. Only few investigations regarding long-term trends of aerosol optical characteristics (e.g. aerosol optical thickness (AOT) and Ångström exponent (ÅE)) have been derived from ground-based observations. This paper aims to derive and discuss linear trends of AOT (440, 675, 870, and 1020 nm) and ÅE (440-870 nm) using AErosol RObotic NETwork (AERONET) level 2.0 spectral observations. Additionally, temporal trends of coarse- and fine-mode dominant AOTs (CdAOT and FdAOT) have been estimated by applying an aerosol classification based on accurate ÅE and Ångström exponent difference (ÅED). In order to take into account the fact that cloud disturbance is having a significant influence on the trend analysis of aerosols, we introduce a weighted least squares regression depending on two weights: (1) monthly standard deviation (σt) and (2) number of observations per month (nt). Temporal increase of FdAOTs (440 nm) prevails over newly industrializing countries in East Asia (weighted trends; +6.23% yr-1 at Beijing) and active agricultural burning regions in South Africa (+1.89% yr-1 at Mongu). On the other hand, insignificant or negative trends for FdAOTs are detected over Western Europe (+0.25% yr-1 at Avignon and -2.29% yr-1 at Ispra) and North America (-0.52% yr-1 for GSFC and -0.01% yr-1 at MD_Science_Center). Over desert regions, both increase and decrease of CdAOTs (+3.37% yr-1 at Solar_Village and -1.18% yr-1 at Ouagadougou) are observed depending on meteorological conditions.

  16. Stressful life events and current psychological distress are associated with self-reported hypertension but not with true hypertension: results from a cross-sectional population-based study

    Directory of Open Access Journals (Sweden)

    Fuchs Flávio D

    2008-10-01

    Full Text Available Abstract Background The evidence linking stress to hypertension has been scarcely documented in population-based studies. Methods Participants were selected through a multi-stage probability sampling and interviewed at home, being submitted to measures of demographics, anthropometrics, blood pressure (BP, and risk factors for hypertension. Hypertension was defined as BP ≥ 140/90 mm Hg or use of BP-lowering drugs or as self-reported hypertension. Stressful life events were investigated through an inventory of nine major life events occurring in the year preceding the interview. Psychological distress was evaluated through a facial scale of expression of emotion in the last month. Results In the total, 1,484 adult individuals were investigated. Prevalence of hypertension was lower in individuals who reported any stressful life event in comparison with individuals who did not reported an event (34.3 versus 44.2%, P Conclusion Recent stressful life events and current psychological distress are not associated with hypertension. Associations between stress events and distress with self-reported hypertension are not intermediated by effects of stress on blood pressure, and may be ascribed to negative feeling about disease and not to the disease itself.

  17. Remote sensing of soot carbon – Part 2: Understanding the absorption Ångström exponent

    Directory of Open Access Journals (Sweden)

    G. L. Schuster

    2016-02-01

    Full Text Available Recently, some authors have suggested that the absorption Ångström exponent (AAE can be used to deduce the component aerosol absorption optical depths (AAODs of carbonaceous aerosols in the AERONET database. This AAE approach presumes that AAE ≪ 1 for soot carbon, which contrasts the traditional small particle limit of AAE = 1 for soot carbon. Thus, we provide an overview of the AERONET retrieval, and we investigate how the microphysics of carbonaceous aerosols can be interpreted in the AERONET AAE product. We find that AAE ≪ 1 in the AERONET database requires large coarse mode fractions and/or imaginary refractive indices that increase with wavelength. Neither of these characteristics are consistent with the current definition of soot carbon, so we explore other possibilities for the cause of AAE ≪ 1. AAE is related to particle size, and coarse mode particles have a smaller AAE than fine mode particles for a given aerosol mixture of species. We also note that the mineral goethite has an imaginary refractive index that increases with wavelength, is very common in dust regions, and can easily contribute to AAE ≪ 1. We find that AAE ≪ 1 can not be caused by soot carbon, unless soot carbon has an imaginary refractive index that increases with wavelength throughout the visible and near-infrared spectrums. Finally, AAE is not a robust parameter for separating carbonaceous absorption from dust aerosol absorption in the AERONET database.

  18. RSS-Based Method for Sensor Localization with Unknown Transmit Power and Uncertainty in Path Loss Exponent.

    Science.gov (United States)

    Huang, Jiyan; Liu, Peng; Lin, Wei; Gui, Guan

    2016-09-08

    The localization of a sensor in wireless sensor networks (WSNs) has now gained considerable attention. Since the transmit power and path loss exponent (PLE) are two critical parameters in the received signal strength (RSS) localization technique, many RSS-based location methods, considering the case that both the transmit power and PLE are unknown, have been proposed in the literature. However, these methods require a search process, and cannot give a closed-form solution to sensor localization. In this paper, a novel RSS localization method with a closed-form solution based on a two-step weighted least squares estimator is proposed for the case with the unknown transmit power and uncertainty in PLE. Furthermore, the complete performance analysis of the proposed method is given in the paper. Both the theoretical variance and Cramer-Rao lower bound (CRLB) are derived. The relationships between the deterministic CRLB and the proposed stochastic CRLB are presented. The paper also proves that the proposed method can reach the stochastic CRLB.

  19. Generalized Hurst exponent and multifractal function of original and translated texts mapped into frequency and length time series

    Science.gov (United States)

    Ausloos, M.

    2012-09-01

    A nonlinear dynamics approach can be used in order to quantify complexity in written texts. As a first step, a one-dimensional system is examined: two written texts by one author (Lewis Carroll) are considered, together with one translation into an artificial language (i.e., Esperanto) are mapped into time series. Their corresponding shuffled versions are used for obtaining a baseline. Two different one-dimensional time series are used here: one based on word lengths (LTS), the other on word frequencies (FTS). It is shown that the generalized Hurst exponent h(q) and the derived f(α) curves of the original and translated texts show marked differences. The original texts are far from giving a parabolic f(α) function, in contrast to the shuffled texts. Moreover, the Esperanto text has more extreme values. This suggests cascade model-like, with multiscale time-asymmetric features as finally written texts. A discussion of the difference and complementarity of mapping into a LTS or FTS is presented. The FTS f(α) curves are more opened than the LTS ones.

  20. Phase transition in anisotropic holographic superfluids with arbitrary dynamical critical exponent z and hyperscaling violation factor α

    Science.gov (United States)

    Park, Miok; Park, Jiwon; Oh, Jae-Hyuk

    2017-11-01

    Einstein-scalar- U(2) gauge field theory is considered in a spacetime characterized by α and z, which are the hyperscaling violation factor and the dynamical critical exponent, respectively. We consider a dual fluid system of such a gravity theory characterized by temperature T and chemical potential μ . It turns out that there is a superfluid phase transition where a vector order parameter appears which breaks SO(3) global rotation symmetry of the dual fluid system when the chemical potential becomes a certain critical value. To study this system for arbitrary z and α , we first apply Sturm-Liouville theory and estimate the upper bounds of the critical values of the chemical potential. We also employ a numerical method in the ranges of 1 ≤ z ≤ 4 and 0 ≤ α ≤ 4 to check if the Sturm-Liouville method correctly estimates the critical values of the chemical potential. It turns out that the two methods are agreed within 10 percent error ranges. Finally, we compute free energy density of the dual fluid by using its gravity dual and check if the system shows phase transition at the critical values of the chemical potential μ _c for the given parameter region of α and z. Interestingly, it is observed that the anisotropic phase is more favored than the isotropic phase for relatively small values of z and α . However, for large values of z and α , the anisotropic phase is not favored.

  1. Systematically Controlling for the Influence of Age, Sex, Hertz and Time Post-Whole-Body Vibration Exposure on Four Measures of Physical Performance in Community-Dwelling Older Adults: A Randomized Cross-Over Study

    Directory of Open Access Journals (Sweden)

    Harold L. Merriman

    2011-01-01

    Full Text Available Though popular, there is little agreement on what whole-body vibration (WBV parameters will optimize performance. This study aimed to clarify the effects of age, sex, hertz and time on four physical function indicators in community-dwelling older adults (=32. Participants were exposed to 2 min WBV per session at either 2 Hz or 26 Hz and outcome measures were recorded at 2, 20 and 40 min post-WBV. Timed get up-and-go and chair sit-and-reach performances improved post-WBV for both sexes, were significantly different between 2 Hz and 26 Hz treatments (≤0.05 and showed statistically significant interactions between age and gender (≤0.01. Counter movement jump and timed one-legged stance performances showed a similar but non-significant response to 2 Hz and 26 Hz treatments, though male subjects showed a distinct trended response. Age and gender should be statistically controlled and both 2 Hz and 26 Hz exert a treatment effect.

  2. Validation and Expected Error Estimation of Suomi-NNP VIIRS Aerosol Optical Thickness and Angstrom Exponent with AERONET

    Science.gov (United States)

    Huang, Jingfeng; Kondragunta, Shobha; Laszlo, Istvan; Liu, Hongqing; Remer, Lorraine A.; Zhang, Hai; Superczynski, Stephen; Ciren, Pubu; Holben, Brent N.; Petrenko, Maksym

    2016-01-01

    The new-generation polar-orbiting operational environmental sensor, the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (S-NPP) satellite, provides critical daily global aerosol observations. As older satellite sensors age out, the VIIRS aerosol product will become the primary observational source for global assessments of aerosol emission and transport, aerosol meteorological and climatic effects, air quality monitoring, and public health. To prove their validity and to assess their maturity level, the VIIRS aerosol products were compared to the spatiotemporally matched Aerosol Robotic Network (AERONET)measurements. Over land, the VIIRS aerosol optical thickness (AOT) environmental data record (EDR) exhibits an overall global bias against AERONET of 0.0008 with root-mean-square error(RMSE) of the biases as 0.12. Over ocean, the mean bias of VIIRS AOT EDR is 0.02 with RMSE of the biases as 0.06.The mean bias of VIIRS Ocean Angstrom Exponent (AE) EDR is 0.12 with RMSE of the biases as 0.57. The matchups between each product and its AERONET counterpart allow estimates of expected error in each case. Increased uncertainty in the VIIRS AOT and AE products is linked to specific regions, seasons, surface characteristics, and aerosol types, suggesting opportunity for future modifications as understanding of algorithm assumptions improves. Based on the assessment, the VIIRS AOT EDR over land reached Validated maturity beginning 23 January 2013; the AOT EDR and AE EDR over ocean reached Validated maturity beginning 2 May 2012, excluding the processing error period 15 October to 27 November 2012. These findings demonstrate the integrity and usefulness of the VIIRS aerosol products that will transition from S-NPP to future polar-orbiting environmental satellites in the decades to come and become the standard global aerosol data set as the previous generations missions come to an end.

  3. Using local scale exponent to characterize heart rate variability in response to postural changes in people with spinal cord injury

    Directory of Open Access Journals (Sweden)

    Fuyuan eLiao

    2015-05-01

    Full Text Available Heart rate variability (HRV is a promising marker for evaluating the remaining autonomic function in people with spinal cord injury (SCI. HRV is commonly assessed by spectral analysis and detrended fluctuation analysis (DFA. This study aimed to investigate whether local scale exponent α(t can reveal new features of HRV that cannot be reflected by spectral measures and DFA coefficients. We studied 12 participants with SCI and 15 healthy able-bodied controls. ECG signals were continually recorded during 10 min sitting and 10 min prone postures. α(t was calculated for scales between 4 s and 60 s. Because α(t could be overestimated at small scales, we developed an approach for correcting α(t based on previous studies. The simulation results on simulated monofractal time series with α between 0.5 and 1.3 showed that the proposed method can yield improved estimation of α(t. We applied the proposed method to raw RR interval series. The results showed that α(t in healthy controls monotonically decreased with scale at scales between 4 s and 12 s (0.083-0.25 Hz in both the sitting and prone postures, whereas in participants with SCI, α(t slowly decreased at almost all scales. The sharp decreasing trend in α(t in controls suggests a more complex dynamics of HRV in controls. α(t at scales between 4 s (0.25 Hz and around 7 s (0.143 Hz was lower in subjects with SCI than in controls in the sitting posture; α(t at a narrow range of scales around 12 s (0.083 Hz was higher in participants with SCI than in controls in the prone posture. However, none of normalized low frequency (0.04-0.15 Hz power, the ratio of low frequency power to high frequency (0.15-0.4 Hz power and long-term (>11 beats DFA coefficient showed significant difference between healthy controls and subjects with SCI in the prone posture. Our results suggest that α(t can reveal more detailed information in comparison to spectral measures and the standard DFA parameters.

  4. Using local scale exponent to characterize heart rate variability in response to postural changes in people with spinal cord injury

    Science.gov (United States)

    Liao, Fuyuan; Liau, Ben-Yi; Rice, Ian M.; Elliott, Jeannette; Brooks, Ian; Jan, Yih-Kuen

    2015-01-01

    Heart rate variability (HRV) is a promising marker for evaluating the remaining autonomic function in people with spinal cord injury (SCI). HRV is commonly assessed by spectral analysis and detrended fluctuation analysis (DFA). This study aimed to investigate whether local scale exponent α(t) can reveal new features of HRV that cannot be reflected by spectral measures and DFA coefficients. We studied 12 participants with SCI and 15 healthy able-bodied controls. ECG signals were continually recorded during 10 min sitting and 10 min prone postures. α(t) was calculated for scales between 4 and 60 s. Because α(t) could be overestimated at small scales, we developed an approach for correcting α(t) based on previous studies. The simulation results on simulated monofractal time series with α between 0.5 and 1.3 showed that the proposed method can yield improved estimation of α(t). We applied the proposed method to raw RR interval series. The results showed that α(t) in healthy controls monotonically decreased with scale at scales between 4 and 12 s (0.083–0.25 Hz) in both the sitting and prone postures, whereas in participants with SCI, α(t) slowly decreased at almost all scales. The sharp decreasing trend in α(t) in controls suggests a more complex dynamics of HRV in controls. α(t) at scales between 4 (0.25 Hz) and around 7 s (0.143 Hz) was lower in subjects with SCI than in controls in the sitting posture; α(t) at a narrow range of scales around 12 s (0.083 Hz) was higher in participants with SCI than in controls in the prone posture. However, none of normalized low frequency (0.04–0.15 Hz) power, the ratio of low frequency power to high frequency (0.15–0.4 Hz) power and long-term (>11 beats) DFA coefficient showed significant difference between healthy controls and subjects with SCI in the prone posture. Our results suggest that α(t) can reveal more detailed information in comparison to spectral measures and the standard DFA parameters. PMID:26029112

  5. Zero Droplet Stiffness Exponent $\\theta$ is Revealed in Short Range Spin Glasses when Probed with Large Avalanches Induced by Long Range Interactions

    OpenAIRE

    Pazmandi, Ferenc; Zimanyi, Gergely T.

    2009-01-01

    We probe the droplet excitations in short range spin glasses by adding a perturbative long range interaction that decays with distance as a power law: $J/r^{\\sigma}$. It is shown that if the power law exponent $\\sigma$ is smaller than the spatial dimension $d$, the perturbation induces large scale avalanches which roll until they force the system to develop a pseudo gap in the excitation spectrum of the stabilities. This makes the perturbative long range interactions relevant for $\\sigma < \\s...

  6. Review Article: On the relation between the seismic activity and the Hurst exponent of the geomagnetic field at the time of the 2000 Izu swarm

    Directory of Open Access Journals (Sweden)

    F. Masci

    2013-09-01

    Full Text Available Many papers document the observation of earthquake-related precursory signatures in geomagnetic field data. However, the significance of these findings is ambiguous because the authors did not adequately take into account that these signals could have been generated by other sources, and the seismogenic origin of these signals have not been validated by comparison with independent datasets. Thus, they are not reliable examples of magnetic disturbances induced by the seismic activity. Hayakawa et al. (2004 claim that at the time of the 2000 Izu swarm the Hurst exponent of the Ultra-Low-Frequency (ULF: 0.001–10 Hz band of the geomagnetic field varied in accord with the energy released by the seismicity. The present paper demonstrates that the behaviour of the Hurst exponent was insufficiently investigated and also misinterpreted by the authors. We clearly show that during the Izu swarm the changes of the Hurst exponent were strongly related to the level of global geomagnetic activity and not to the increase of the local seismic activity.

  7. A Biomedical Computation Revealed that an Extra-Systolic Heartbeat Exhibits a Lower Scaling Exponent: DFA as a Beneficial Biomedical Tool

    Directory of Open Access Journals (Sweden)

    Toru Yazawa

    2013-06-01

    Full Text Available We made our own DFA (detrended fluctuation analysis program. We applied it for checking characteristics for the heartbeat of various individuals. Healthy subjects showed a normal scaling exponent, which is near 1.0 (ranging 0.9 to 1.19 in our own temporary guideline. This is in agreement with the original report by Peng et al. long time ago. In the present study, we investigated the person who has an extra-systole heartbeat, and revealed that their arrhythmic heartbeat exhibited a low scaling exponent (around 0.7. Alternans, which is the heart beating in period-2 rhythms, exhibited a much low scaling exponent (around 0.6. We may conclude that if it would be possible to make a device that equips a DFA program, it might be useful to check the heart condition, and contribute not only in nonlinear physics but also in biomedical fields; especially as a device for health check, which is applicable for people who are spending an ordinary life, before they get seriously heart sick.

  8. Tendency toward crossover of the effective susceptibility exponent from its doubled Ising value to its doubled mean-field value near a double critical point.

    Science.gov (United States)

    Pradeep, U K

    2008-10-07

    The critical behavior of osmotic susceptibility in an aqueous electrolyte mixture 1-propanol (1P) + water (W) + potassium chloride is reported. This mixture exhibits re-entrant phase transitions and has a nearly parabolic critical line with its apex representing a double critical point (DCP). The behavior of the susceptibility exponent is deduced from static light-scattering measurements, on approaching the lower critical solution temperatures (T(L)'s) along different experimental paths (by varying t) in the one-phase region. The light-scattering data analysis substantiates the existence of a nonmonotonic crossover behavior of the susceptibility exponent in this mixture. For the T(L) far away from the DCP, the effective susceptibility exponent gamma(eff) as a function of t displays a nonmonotonic crossover from its single limit three-dimensional (3D)-Ising value (approximately 1.24) toward its mean-field value with increase in t. While for that closest to the DCP, gamma(eff) displays a sharp, nonmonotonic crossover from its nearly doubled 3D-Ising value toward its nearly doubled mean-field value with increase in t. The renormalized Ising regime extends over a relatively larger t range for the T(L) closest to the DCP, and a trend toward shrinkage in the renormalized Ising regime is observed as T(L) shifts away from the DCP. Nevertheless, the crossover to the mean-field limit extends well beyond t>10(-2) for the T(L)'s studied. The observed crossover behavior is attributed to the presence of strong ion-induced clustering in this mixture, as revealed by various structure probing techniques. As far as the critical behavior in complex or associating mixtures with special critical points (like the DCP) is concerned, our results indicate that the influence of the DCP on the critical behavior must be taken into account not only on the renormalization of the critical exponent but also on the range of the Ising regime, which can shrink with decrease in the influence of the

  9. Generalized Hertz model for bimodal nanomechanical mapping

    Directory of Open Access Journals (Sweden)

    Aleksander Labuda

    2016-07-01

    Full Text Available Bimodal atomic force microscopy uses a cantilever that is simultaneously driven at two of its eigenmodes (resonant modes. Parameters associated with both resonances can be measured and used to extract quantitative nanomechanical information about the sample surface. Driving the first eigenmode at a large amplitude and a higher eigenmode at a small amplitude simultaneously provides four independent observables that are sensitive to the tip–sample nanomechanical interaction parameters. To demonstrate this, a generalized theoretical framework for extracting nanomechanical sample properties from bimodal experiments is presented based on Hertzian contact mechanics. Three modes of operation for measuring cantilever parameters are considered: amplitude, phase, and frequency modulation. The experimental equivalence of all three modes is demonstrated on measurements of the second eigenmode parameters. The contact mechanics theory is then extended to power-law tip shape geometries, which is applied to analyze the experimental data and extract a shape and size of the tip interacting with a polystyrene surface.

  10. Characterizing the Hertz-VPM Polarimeter

    Science.gov (United States)

    Krejny; Novak; Chuss; Voellmer; Moseley; Wollack; Benford; Stauguhn; Jackson; Loewenstein; hide

    2008-01-01

    We present preliminary results from engineering tests conducted at Northwestern U. and the Submillimeter Telescope Observatory (SMTO) on Mt. Graham, AZ. The VPM provides a new method for modulating incoming polarization signals, using small linear translations instead of rotational motion. Our dual grid-mirror design has several advantages over the currently favored technology, the half-wave plate. The VPM appears to successfully modulate submillimeter polarization, with high efficiencies and low instrumental polarization. We briefly discuss feasibility of use for air- and space-born applications.

  11. A new approach for the determination of cementation exponent in different petrofacies with velocity deviation logs and petrographical studies in the carbonate Asmari formation

    Science.gov (United States)

    Kazemzadeh, E.; Nabi-Bidhendi, M.; Keramati Moezabad, M.; Rezaee, M. R.; Saadat, K.

    2007-06-01

    This study was carried out to develop an approach applicable for the determination of the cementation exponent in Archie's formula for complex carbonate reservoirs. Evaluation of hydrocarbon saturation is very important in oil reservoir studies. Archie's are the basic equations for saturation evaluation. The coefficients in these equations are normally determined from laboratory data. Archie presented values for these coefficients, which are constants for a sandstone lithology. Because carbonate rocks show drastic variations in lithology due to different texture and pore types, Archie's coefficients, which are more influenced by pore type, should be determined for different types of carbonate. Uncertainties in these coefficients cause many errors in saturation evaluation, especially for oil in situ. The value of the cementation exponent is the main factor that can cause error in saturation determination. In this study, Archie's parameters (a and m) were determined in the laboratory for various petrofacies based on both petrographic studies and CT images. Due to the high dependence of seismic wave velocity on pore shape in carbonate rocks, petrofacies were also determined by using wave velocity deviation logs. Archie's parameters were then determined for each petrofacies. The results showed that cementation exponent increases in value with increasing velocity deviation values. It is concluded that the correlation coefficient for different petrofacies obtained from velocity deviation logs is comparatively higher than that obtained solely from petrographic studies. Considering the fact that petrophysical data are more accessible than core-based petrography data, the method presented in this study appears to provide a more useful approach in determining Archie's coefficients.

  12. Dynamic Features of the Highly Excited Vibrational States of the HOCl Non-Integrable System Based on the Dynamic Potential and Lyapunov Exponent Approaches.

    Science.gov (United States)

    Wang, Aixing; Fang, Chao; Liu, Yibao

    2017-01-07

    In this article the dynamic features of the highly excited vibrational states of the hypochlorous acid (HOCl) non-integrable system are studied using the dynamic potential and Lyapunov exponent approaches. On the condition that the 3:1 resonance between the H-O stretching and H-O-Cl bending modes accompany the 2:1 Fermi resonance between the O-Cl stretching and H-O-Cl bending modes, it is found that the dynamic potentials of the highly excited vibrational states vary regularly with different Polyad numbers (P numbers). As the P number increases, the dynamic potentials of the H-O stretching mode remain the same, but those of the H-O-Cl bending mode gradually become complex. In order to investigate the chaotic and stable features of the highly excited vibrational states of the HOCl non-integrable system, the Lyapunov exponents of different energy levels lying in the dynamic potentials of the H-O-Cl bending mode (P = 4 and 5) are calculated. It is shown that the Lyapunov exponents of the energy levels staying in the junction of Morse potential and inverse Morse potential are relative large, which indicates the degrees of chaos for these energy levels is relatively high, but the stabilities of the corresponding states are good. These results could be interpreted as the intramolecular vibrational relaxation (IVR) acting strongly via the HOCl bending motion and causing energy transfers among different modes. Based on the previous studies, these conclusions seem to be generally valid to some extent for non-integrable triatomic molecules.

  13. Trend analysis of the Aerosol Optical Thickness and Ångström Exponent derived from the global AERONET spectral observations

    Science.gov (United States)

    Yoon, J.; von Hoyningen-Huene, W.; Kokhanovsky, A. A.; Vountas, M.; Burrows, J. P.

    2011-08-01

    Regular aerosol observations based on well-calibrated instruments have led to a better understanding of the aerosol radiative budget on Earth. In recent years, these instruments have played an important role in the determination of the increase of anthropogenic aerosols by means of long-term studies. Only few investigations regarding long-term trends of aerosol optical characteristics (e.g. Aerosol Optical Thickness (AOT) and Ångström Exponent (ÅE)) have been derived from ground-based observations. This paper aims to derive and discuss linear trends of AOT (440, 675, 870, and 1020 nm) and ÅE (440-870 nm) using AErosol RObotic NETwork (AERONET) spectral observations. Additionally, temporal trends of Coarse- and Fine-mode dominant AOTs (CAOT and FAOT) have been estimated by applying an aerosol classification based on accurate ÅE and Ångström Exponent Difference (ÅED). In order to take into account the fact that cloud disturbance is having a significant influence on the trend analysis of aerosols, we introduce a weighted least squares regression depending on two weights: (1) monthly standard deviation and (2) Number of Observations (NO) per month. Temporal increase of FAOTs prevails over regions dominated by emerging economy or slash-burn agriculture in East Asia and South Africa. On the other hand, insignificant or negative trends for FAOTs are detected over Western Europe and North America. Over desert regions, both increase and decrease of CAOTs are observed depending on meteorological conditions.

  14. Prediction of propofol clearance in children from an allometric model developed in rats, children and adults versus a 0.75 fixed-exponent allometric model.

    Science.gov (United States)

    Peeters, Mariska Y M; Allegaert, Karel; Blussé van Oud-Alblas, Heleen J; Cella, Massimo; Tibboel, Dick; Danhof, Meindert; Knibbe, Catherijne A J

    2010-04-01

    For propofol clearance, allometric scaling has been applied successfully for extrapolations between species (rats and humans) and within the human bodyweight range (children and adults). In this analysis, the human bodyweight range is explored to determine for which range an allometric model with a fixed or estimated exponent can be used to predict propofol clearance, without correction for maturation. The predictive value of the allometric equation, clearance (CL) is equal to 0.071 x bodyweight in kg0.78, which was developed from rats, children and adults, and the predictive value of a fixed exponent allometric model derived from the basal metabolic rate, CL is equal to CL standardized to a 70 kg adult x (bodyweight in kg standardized to a 70 kg adult)0.75, were evaluated across five independent patient groups including (i) 25 (pre)term neonates with a postmenstrual age of 27-43 weeks; (ii) 22 postoperative infants aged 4-18 months; (iii) 12 toddlers aged 1-3 years; (iv) 14 adolescents aged 10-20 years; and (v) 26 critically ill adults sedated long term. The median percentage error of the predictions was calculated using the equation %error = (CL(allometric) - CL(i))/CL(i) x 100, where CL(allometric) is the predicted propofol clearance from the allometric equations for each individual and CL(i) is the individual-predicted (post hoc) propofol clearance value derived from published population pharmacokinetic models. In neonates, the allometric model developed from rats, children and adults, and the fixed-exponent allometric model, systematically overpredicted individual propofol clearance, with median percentage errors of 288% and 216%, respectively, whereas in infants, both models systematically underpredicted individual propofol clearance, with median percentage errors of -43% and -55%, respectively. In toddlers, adolescents and adults, both models performed reasonably well, with median percentage errors of -12% and -32%, respectively, in toddlers, 16% and -14

  15. Se analiza la teoría de Jorge Juan sobre la resistencia fluídica, tal como la expone en el Examen

    Directory of Open Access Journals (Sweden)

    Simón Calero, Julián

    2001-12-01

    Full Text Available The Jorge Juan theory on fluid resistance is analysed as stated in the Examen Marítimo. The theoretical basis and applications are studied, these range from flat plates to ship hull and sails. The article concludes with a revision of what Juan considers to be its experimental basis and possible forerunners of his theory are traced.

    Se analiza la teoría de Jorge Juan sobre la resistencia fluídica, tal como la expone en el Examen Marítimo. Se estudian las bases teóricas y sus aplicaciones, desde placas planas hasta cacos y velas de buques. Se concluye con una revisión de lo que Juan considera sus fundamentos experimentales y se rastrean los posibles antecedentes de su teoría.

  16. Research note on a parabolic heat-balance integral method with unspecified exponent: An entropy generation approach in optimal profile determination

    Directory of Open Access Journals (Sweden)

    Hristov Jordan

    2009-01-01

    Full Text Available The heat-balance integral method of Goodman is studied with two simple 1-D heat conduction problems with prescribed temperature and flux boundary conditions. These classical problems with well known exact solutions enable to demonstrate the heat-balance integral method performance by a parabolic profile and the entropy generation minimization concept in definition of the appropriate profile exponent. The basic assumption generating the additional constraints needed to perform the solution is based on the requirement to minimize the difference in the local thermal entropy generation rates calculated by the approximate and the exact profile, respectively. This concept is easily applicable since the general concept has simple implementation of the condition requiring the thermal entropy generations calculated through both profiles to be the same at the boundary. The entropy minimization generation approach automatically generates the additional requirement which is deficient in the set of conditions defined by the heat-balance integral method concept.

  17. Confiabilidade do relato de eventos de vida estressantes em um questionário autopreenchido: Estudo Pró-Saúde Reliability of reported stressful life events reported in a self-administered questionnaire: Pró-Saúde Study

    Directory of Open Access Journals (Sweden)

    Claudia S Lopes

    2001-09-01

    Full Text Available OBJETIVO: Avaliar a confiabilidade do relato de eventos de vida estressantes (EVE, integrantes de um questionário multidimensional preenchido por uma amostra de funcionários de uma universidade pública. MÉTODOS: Utilizou-se um desenho de estudo de confiabilidade teste-reteste, com um intervalo de duas semanas entre as duas aferições, como parte de um estudo-piloto realizado em uma amostra de 192 funcionários contratados de uma universidade pública no Rio de Janeiro. A avaliação dos EVE foi feita por meio de perguntas fechadas, com respostas dicotômicas, cobrindo os seguintes eventos nos 12 meses anteriores: doença séria; internação hospitalar; morte de parente próximo; problemas financeiros severos; mudança forçada de moradia; separação/divórcio; agressão física; assalto/roubo; e experiência de diversos tipos de discriminação. A análise da confiabilidade foi feita com estratificação por gênero e escolaridade dos respondentes, utilizando-se o coeficiente kappa. RESULTADOS: Os resultados mostraram uma confiabilidade "substancial" a "quase perfeita" (kappa entre 0,62 e 1,00, para homens e mulheres, nas questões referentes a: internação hospitalar, falecimento de parente próximo, dificuldades financeiras severas, rompimento de relação amorosa e assalto/roubo. Para a maioria do eventos, houve diferenças importantes nos valores do kappa segundo o grau de escolaridade dos respondentes; para a maioria das perguntas, o grupo com maior escolaridade obteve melhores resultados. CONCLUSÃO: Os achados sugerem que a utilização de perguntas discretas sobre EVE em um questionário para autopreenchimento é adequada, com a maioria das questões apresentando boa estabilidade quando aplicada a adultos de diferentes níveis de escolaridade.OBJECTIVE: To evaluate the reliability of reported stressful life events in a multidimensional self-administered questionnaire. METHODS: A test-retest design was used as a part of a pilot

  18. Time exponent suppression of growth of the Zr–Sn diffusion layers between amorphous Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} and Sn

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Kan [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Lin, Tiesong, E-mail: hitjoining@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); He, Peng [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Sun, Jianfei [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-10-15

    The growth kinetics of the diffusion layer between molten Sn and Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} bulk metallic glass (BMG) substrate were examined by isothermal aging at the temperature range between 513 and 633 K with 30 K temperature interval. The aged samples were characterized by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The growth of the diffusion layer is mainly controlled by a diffusion-controlled mechanism over the temperature range at stage I, and the value of the time exponent is approximately 1/2 by fitting the experiment data. As well as there is unusual stage II, whose time exponent of the growth is suppressed to 1/3. Based on phenomenological description, it could deduced that phase transition such like nucleation and coalescence occur in vicinity of the interface of diffusion layer at the late stage of clusters growth processes similar to Ostwald ripening. - Highlights: • Linear fitting of all experiment data of the thickness derivate the time exponent n be suppressed from 0.52 to 0.36. • There is the value of the time exponent following two stages by fitting the data segmentations. • The value of the time exponent is 1/2 at stage I, and 1/3 at stage II. • Phase transition such like nucleation, coalescence occur in vicinity of the interface of diffusion layer at stage II.

  19. Use of Archived Neonatal Bloodspots for Examining Associations Between Prenatal Exposure to Potentially Traumatic or Stressful Life Events, Maternal Herpesvirus Infection and Lifetime History of Generalized Anxiety Disorder in Offspring

    Directory of Open Access Journals (Sweden)

    Amanda M. Simanek

    2016-08-01

    Full Text Available Background: Lifetime prevalence of anxiety disorders is over 32% among U.S. adolescents, warranting further investigation into early life risk factors for such conditions. We conducted a pilot study to examine the role that maternal herpesvirus infection may play in the pathway between maternal trauma and stress during pregnancy and offspring generalized anxiety disorder (GAD. Methods: Participants included 69 women in the Detroit Neighborhood Health Study with data on past exposure to 19 potentially traumatic (PTEs and 9 stressful life events (SLEs. Lifetime history of GAD in the youngest biologic child between 6-17 years old born in Michigan (i.e., index child of each woman was ascertained via the Diagnostic Interview Schedule for Children, 4th edition, parent version. We obtained written informed consent from participants for retrieval of archived neonatal bloodspot samples corresponding to their index child from the Michigan Neonatal Biobank (MNB and testing of these samples for markers of maternal herpes simplex virus (HSV-1 and cytomegalovirus (CMV seropositivity. Logistic regression was used to examine the association between maternal PTEs or SLEs during pregnancy and offspring GAD. Results: A total of 18.1% and 31.9% of women experienced ≥ 1 PTE or SLE during pregnancy, respectively, and 10.8% of offspring met the criteria for lifetime history of GAD. We obtained maternal consent for retrieval of and tested bloodspot samples corresponding to the index child of 22 women (38%, of which 4.5% and 40.9% were seropositive for HSV-1 and CMV, respectively. We observed positive, although not statistically significant associations between ≥ 1 PTE or SLE during pregnancy and offspring lifetime history of GAD. While a greater proportion of offspring with lifetime history of GAD were born to women seropositive for CMV and HSV-1, compared to those without lifetime history, these differences were not statistically significant and we did not further

  20. Depressive symptoms and stressful life events predict metabolic syndrome among middle-aged women: a comparison of World Health Organization, Adult Treatment Panel III, and International Diabetes Foundation definitions.

    Science.gov (United States)

    Räikkönen, Katri; Matthews, Karen A; Kuller, Lewis H

    2007-04-01

    We evaluated whether psychosocial factors that are related to cardiovascular disease and type 2 diabetes predict prospectively the risk for the metabolic syndrome using the different clinical criteria available for defining the syndrome. Women were enrolled in a population-based prospective cohort study called the Healthy Women Study and were followed for an average of 15 years after baseline. Metabolic syndrome was defined via the World Health Organization, the National Cholesterol Education Program Adult Treatment Panel III, and the International Diabetes Foundation clinical criteria. Among women who did not have the metabolic syndrome at the baseline, the risk for the metabolic syndrome defined in multiple ways varied from 1.21- to 2.12-fold ([95% CI 1.00-4.25], P < 0.05) for more severe depressive symptoms or very stressful life event(s). These associations were largely the same, regardless of the clinical criteria used to define the metabolic syndrome. Those who at the baseline reported feeling frequently and intensely angry, tense, or stressed also had an increased risk for developing the metabolic syndrome at least by one definition (relative risk 1.19-1.66 [1.00-2.39]). These are the first data to demonstrate that psychosocial factors predict the risk for developing the metabolic syndrome by multiple definitions. Psychosocial factors may play a causal role in the chain of events leading to the metabolic syndrome.

  1. Limitation of using Angstrom exponent for source apportionment of black carbon in complex environments - A case study from the North West Indo- Gangetic plain

    Science.gov (United States)

    Garg, S.; Sinha, B.; Sinha, V.; Chandra, P.; Sarda Esteve, R.; Gros, V.

    2015-12-01

    Determining the contribution of different sources to the total BC is necessary for targeted mitigation. Absorption Angstrom exponent (αabs) measurements of black carbon (BC) have recently been introduced as a novel tool to apportion the contribution of biomass burning sources to BC. Two-component Aethalometer model for apportioning BC to biomass burning sources and fossil fuel combustion sources, which uses αabs as a generic indicator of the source type, is widely used for determining the contribution of the two types of sources to the total BC. Our work studies BC emissions in the highly-populated, anthropogenic emissions-dominated Indo-Gangetic Plain and demonstrates that the αabs cannot be used as a generic tracer for biomass burning emissions in a complex environment. Simultaneously collected high time resolution data from a 7-wavelength Aethalometer (AE 42, Magee Scientific, USA) and a high sensitivity Proton Transfer Reaction- Quadrupole Mass Spectrometer (PTR-MS) installed at a sub-urban site in Mohali (Punjab), India, were used to identify a number of biomass combustion plumes during which BC enhancements correlated strongly with an increase in acetonitrile (a well-established biomass burning tracer) mixing ratio. Each type of biomass combustion is classified and characterized by distinct emission ratios of aromatic compounds and oxygenated VOCs to acetonitrile. The identified types of biomass combustion include two different types of crop residue burning (paddy and wheat), burning of leaf-litter, and garbage burning. Traffic (fossil-fuel burning) plumes were also selected for comparison. We find that the two-component Aethalometer source-apportionment method cannot be extrapolated to all types of biomass combustion and αabs of traffic plumes can be >1 in developing countries like India, where use of adulterated fuel in vehicles is common. Thus in a complex environment, where multiple anthropogenic BC sources and air masses of variable photochemical age

  2. Using the Aerosol Single Scattering Albedo and Angstrom Exponent from AERONET to Determine Aerosol Origins and Mixing States over the Indo-Gangetic Plain

    Science.gov (United States)

    Giles, D. M.; Holben, B. N.; Eck, T. F.; Sinyuk, A.; Slutsker, I.; Smirnov, A.; Schafer, J. S.; Dickerson, R. R.; Thompson, A. M.; Tripathi, S. N.; Singh, R. P.; Ghauri, B.

    2012-12-01

    Aerosol mixtures—whether dominated by dust, carbon, sulfates, nitrates, sea salt, or mixtures of them—complicate the retrieval of remotely sensed aerosol properties from satellites and possibly increase the uncertainty of the aerosol radiative impact on climate. Major aerosol source regions in South Asia include the Thar Desert as well as agricultural lands, Himalayan foothills, and large urban centers in and near the Indo-Gangetic Plain (IGP). Over India and Pakistan, seasonal changes in meteorology, including the monsoon (June-September), significantly affect the transport, lifetime, and type of aerosols. Strong monsoonal winds can promote long range transport of dust resulting in mixtures of dust and carbonaceous aerosols, while more stagnant synoptic conditions (e.g., November-January) can prolong the occurrence of urban/industrial pollution, biomass burning smoke, or mixtures of them over the IGP. Aerosol Robotic Network (AERONET) Sun/sky radiometer data are analyzed to show the aerosol optical depth (AOD) seasonality and aerosol dominant mixing states. The Single Scattering Albedo (SSA) and extinction Angstrom exponent (EAE) relationship has been shown to provide sound clustering of dominant aerosol types using long term AERONET site data near known source regions [Giles et al., 2012]. In this study, aerosol type partitioning using the SSA (440 nm) and EAE (440-870 nm) relationship is further developed to quantify the occurrence of Dust, Mixed (e.g., dust and carbonaceous aerosols), Urban/Industrial (U/I) pollution, and Biomass Burning (BB) smoke. Based on EAE thresholds derived from the cluster analysis (for AOD440nm>0.4), preliminary results (2001-2010) for Kanpur, India, show the overall contributions of each dominant particle type (rounded to the nearest 10%): 10% for Dust (EAE≤0.25), 60% for Mixed (0.251.25). In the IGP, BB aerosols may have varying sizes (e.g., corresponding to 1.2agricultural waste, forest, or dung burning), combustion phases, or

  3. Scaling Exponents in Financial Markets

    Science.gov (United States)

    Kim, Kyungsik; Kim, Cheol-Hyun; Kim, Soo Yong

    2007-03-01

    We study the dynamical behavior of four exchange rates in foreign exchange markets. A detrended fluctuation analysis (DFA) is applied to detect the long-range correlation embedded in the non-stationary time series. It is for our case found that there exists a persistent long-range correlation in volatilities, which implies the deviation from the efficient market hypothesis. Particularly, the crossover is shown to exist in the scaling behaviors of the volatilities.

  4. Characterization of the structure and cross-shore transport properties of a coastal upwelling filament using three-dimensional finite-size Lyapunov exponents

    Science.gov (United States)

    Bettencourt, João. H.; Rossi, Vincent; Hernández-García, Emilio; Marta-Almeida, Martinho; López, Cristóbal

    2017-09-01

    The three-dimensional structure, dynamics, and dispersion characteristics of a simulated upwelling filament in the Iberian upwelling system are analyzed using Lagrangian tools. We used a realistic regional simulation of the western Iberian shelf which is concomitant with an in situ oceanographic campaign that surveyed the area. We compute 3-D fields of finite-size Lyapunov exponents (FSLE) from 3-D velocity fields and extract the field's ridges to study the spatial distribution and temporal evolution of the Lagrangian Coherent Structures (LCSs) evolving around the filament. We find that the most intense curtain-like LCSs delimit the boundaries of the whole filamentary structure whose general properties match well the observations. The filament interior is characterized by small dispersion of fluid elements. Furthermore, we identify a weak LCS separating the filament into a warmer vein and a colder filament associated with the interaction of a mesoscale eddy with the upwelling front. The cold upwelled water parcels move along the filament conserving their density. The filament itself is characterized by small dispersion of fluid elements in its interior. The comparison of LCSs with potential temperature and salinity gradient fields shows that the outer limits of the filament coincide with regions of large hydrographic gradients, similar to those observed, explaining the isolation of the interior of the filament with the surrounding waters. We conclude that the Lagrangian analysis used in this work is useful in explaining the dynamics of cross-shore exchanges of materials between coastal regions and the open ocean due to mesoscale processes.

  5. Proneness to social anxiety modulates neural complexity in the absence of exposure: A resting state fMRI study using Hurst exponent.

    Science.gov (United States)

    Gentili, Claudio; Vanello, Nicola; Cristea, Ioana; David, Daniel; Ricciardi, Emiliano; Pietrini, Pietro

    2015-05-30

    To test the hypothesis that brain activity is modulated by trait social anxiety, we measured the Hurst Exponent (HE), an index of complexity in time series, in healthy individuals at rest in the absence of any social trigger. Functional magnetic resonance imaging (fMRI) time series were recorded in 36 subjects at rest. All volunteers were healthy without any psychiatric, medical or neurological disorder. Subjects completed the Liebowitz Social Anxiety Scale (LSAS) and the Brief Fear of Negative Evaluation (BFNE) to assess social anxiety and thoughts in social contexts. We also obtained the fractional Amplitude of Low Frequency Fluctuations (fALFF) of the BOLD signal as an independent control measure for HE data. BFNE scores correlated positively with HE in the posterior cingulate/precuneus, while LSAS scores correlated positively with HE in the precuneus, in the inferior parietal sulci and in the parahippocamus. Results from fALFF were highly consistent with those obtained using LSAS and BFNE to predict HE. Overall our data indicate that spontaneous brain activity is influenced by the degree of social anxiety, on a continuum and in the absence of social stimuli. These findings suggest that social anxiety is a trait characteristic that shapes brain activity and predisposes to different reactions in social contexts. Copyright © 2015. Published by Elsevier Ireland Ltd.

  6. Stressful life events and cancer risk

    DEFF Research Database (Denmark)

    Bergelt, C; Prescott, E; Grønbaek, M

    2006-01-01

    In a prospective cohort study in Denmark of 8736 randomly selected people, no evidence was found among 1011 subjects who developed cancer that self-reported stressful major life events had increased their risk for cancer.......In a prospective cohort study in Denmark of 8736 randomly selected people, no evidence was found among 1011 subjects who developed cancer that self-reported stressful major life events had increased their risk for cancer....

  7. Stressful life events and leucocyte telomere length

    DEFF Research Database (Denmark)

    Osler, Merete; Bendix, Laila; Rask, Lene

    2016-01-01

    life events and TL was analysed using structural equation modelling, which also provided an estimate of the proportion of the total effect mediated by somatic and mental health (cardiovascular disease, body mass and depressive mood), lifestyle factors, and low grade inflammation (C-reactive protein...

  8. Interference-Fit Life Factors for Ball Bearings

    Science.gov (United States)

    Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

    2010-01-01

    The effect of hoop stresses on the rolling-element fatigue life of angular-contact and deep-groove ball bearings was determined for common inner-ring interference fits at the ABEC-5 tolerance level. The analysis was applied to over 1150 bearing configurations and load cases. Hoop stresses were superimposed on the Hertzian principal stresses created by the applied bearing load to calculate the inner-race maximum shearing stress. The resulting fatigue life of the bearing was recalculated through a series of equations. The reduction in the fatigue life is presented as life factors that are applied to the unfactored bearing life. The life factors found in this study ranged from 1.00 (no life reduction)--where there was no net interface pressure--to a worst case of 0.38 (a 62-percent life reduction). For a given interference fit, the reduction in life is different for angular-contact and deep-groove ball bearings. Interference fits also affect the maximum Hertz stress-life relation. Experimental data of Czyzewski, showing the effect of interference fit on rolling-element fatigue life, were reanalyzed to determine the shear stress-life exponent. The Czyzewski data shear stress-life exponent c equals 8.77, compared with the assumed value of 9. Results are presented as tables and charts of life factors for angular-contact and deep-groove ball bearings with light, normal, and heavy loads and interference fits ranging from extremely light to extremely heavy.

  9. Validation and expected error estimation of Suomi-NPP VIIRS aerosol optical thickness and Ångström exponent with AERONET

    Science.gov (United States)

    Huang, Jingfeng; Kondragunta, Shobha; Laszlo, Istvan; Liu, Hongqing; Remer, Lorraine A.; Zhang, Hai; Superczynski, Stephen; Ciren, Pubu; Holben, Brent N.; Petrenko, Maksym

    2016-06-01

    The new-generation polar-orbiting operational environmental sensor, the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (S-NPP) satellite, provides critical daily global aerosol observations. As older satellite sensors age out, the VIIRS aerosol product will become the primary observational source for global assessments of aerosol emission and transport, aerosol meteorological and climatic effects, air quality monitoring, and public health. To prove their validity and to assess their maturity level, the VIIRS aerosol products were compared to the spatiotemporally matched Aerosol Robotic Network (AERONET) measurements. Over land, the VIIRS aerosol optical thickness (AOT) environmental data record (EDR) exhibits an overall global bias against AERONET of -0.0008 with root-mean-square error (RMSE) of the biases as 0.12. Over ocean, the mean bias of VIIRS AOT EDR is 0.02 with RMSE of the biases as 0.06. The mean bias of VIIRS Ocean Ångström Exponent (AE) EDR is 0.12 with RMSE of the biases as 0.57. The matchups between each product and its AERONET counterpart allow estimates of expected error in each case. Increased uncertainty in the VIIRS AOT and AE products is linked to specific regions, seasons, surface characteristics, and aerosol types, suggesting opportunity for future modifications as understanding of algorithm assumptions improves. Based on the assessment, the VIIRS AOT EDR over land reached Validated maturity beginning 23 January 2013; the AOT EDR and AE EDR over ocean reached Validated maturity beginning 2 May 2012, excluding the processing error period 15 October to 27 November 2012. These findings demonstrate the integrity and usefulness of the VIIRS aerosol products that will transition from S-NPP to future polar-orbiting environmental satellites in the decades to come and become the standard global aerosol data set as the previous generations' missions come to an end.

  10. Expanding care for perinatal women with depression (EXPONATE): study protocol for a randomized controlled trial of an intervention package for perinatal depression in primary care.

    Science.gov (United States)

    Gureje, Oye; Oladeji, Bibilola Damilola; Araya, Ricardo; Montgomery, Alan A; Kola, Lola; Kirmayer, Laurence; Zelkowitz, Phyllis; Groleau, Danielle

    2015-06-30

    Depression is common among women during perinatal period and is associated with long-term adverse consequences for the mother and infant. In Nigeria, as in many other low- and-middle-income countries (LMIC), perinatal depression usually goes unrecognized and untreated. The aim of EXPONATE is to test the effectiveness and cost-effectiveness of an intervention package for perinatal depression delivered by community midwives in primary maternal care in which physician support and enhanced patient compliance are implemented using mobile phones. A pragmatic two-arm parallel cluster randomized controlled trial was designed. The units of allocation are the primary maternal care clinics. Thirty eligible and consenting clinics were randomized but, due to problems with logistics, 29 eventually participated. Consenting pregnant women with a gestational age between 16 and 28 weeks who screened positive on the Edinburgh Postnatal Depression Scale (EPDS score ≥12), absent psychosis or bipolar disorder, and not actively suicidal were recruited into the trial (N = 686). Midwives in the intervention arm were trained to deliver psychoeducation, problem solving treatment, and parenting skills. Eight weekly sessions were delivered following entry into the study. Further sessions during pregnancy and 6 weeks following childbirth were determined by level of depressive symptoms. Clinical support and supervision, delivered mainly by mobile phone, were provided by general physicians and psychiatrists. Automated text and voice messages, also delivered by mobile phones, were used to facilitate patient compliance with clinic appointments and 'homework' tasks. Patients in the control arm received care as usual enhanced by further training of the providers in that arm in the recognition and standard treatment of depression. Assessments are undertaken at baseline, 2 months following recruitment into the study and 3, 6, 9 and 12 months after childbirth. The primary outcome is recovery from

  11. Associação de eventos de vida produtores de estresse e mal-estar psicológico: um estudo de base populacional Association of stressful life events and psychological distress: a community-based study

    Directory of Open Access Journals (Sweden)

    Felipe Sparrenberger

    2004-02-01

    from socioeconomic variables (education 38.2%; family income, 32.3% and the occurrence of at least one event (36.4%. Public policies aimed at ameliorating adverse social factors such as loss of employment and crime, as well as social support to help individuals manage stressful life events are likely to improve psychological well-being.

  12. Eventos de vida produtores de estresse e transtornos mentais comuns: resultados do Estudo Pró-Saúde Stressful life events and common mental disorders: results of the Pro-Saude Study

    Directory of Open Access Journals (Sweden)

    Claudia S. Lopes

    2003-12-01

    Full Text Available O objetivo do estudo é investigar a associação entre eventos de vida produtores de estresse (EVPE e transtornos mentais comuns (TMC. Dados seccionais da fase 1 de um estudo de coorte (Estudo Pró-Saúde foram coletados entre 4.030 funcionários. Informações foram obtidas por meio de um questionário multidimensional autopreenchível (General Health Questionnaire que avaliou a presença de TMC nas duas semanas anteriores, ocorrência de EVPE nos 12 meses anteriores e variáveis sociodemográficas. Após ajuste por sexo, idade, renda e situação conjugal, problemas financeiros graves foram os eventos associados a uma chance mais elevada de TMC (OR = 2,6; IC95%: 2,2-3,0, seguidos de agressão física (OR = 2,1; IC95%: 1,5-2,9, mudança forçada de moradia (OR = 1,9; IC95%: 1,5-2,4, doença grave (OR = 1,8; IC95%: 1,5-2,1, rompimento de relação amorosa (OR = 1,9; IC95%: 1,6-2,3, internação hospitalar (OR = 1,4; IC95%: 1,1-1,8 e assalto ou roubo (OR = 1,5; IC95%: 1,2-1,8. Os resultados apontam para a necessidade de se investigar efeitos de longo prazo associados a estes eventos, assim como de fatores que potencialmente modifiquem seu impacto, de forma a subsidiar ações de prevenção mais efetivas na área da saúde mental.This study investigates the association between stressful life events (SLE and common mental disorders (CMD among university employees in Rio de Janeiro, Brazil. Phase 1 sectional data from a cohort study (the Pro-Saude Study were collected among 4,030 participants. A standardized self-administered questionnaire (General Health Questionnaire assessed the presence of CMD during the previous two weeks, the occurrence of SLE in the previous 12 months, and socio-demographic characteristics. After adjustment for gender, age, income, and marital status, severe financial problems were associated with the greatest risk of CMD (OR = 2.6; 95%CI: 2.2-3.0, followed by physical aggression (OR = 2.1; 95%CI: 1.5-2.8, disruption of a

  13. Evaluation of the absorption Ångström exponents for traffic and wood burning in the Aethalometer-based source apportionment using radiocarbon measurements of ambient aerosol

    Science.gov (United States)

    Zotter, Peter; Herich, Hanna; Gysel, Martin; El-Haddad, Imad; Zhang, Yanlin; Močnik, Griša; Hüglin, Christoph; Baltensperger, Urs; Szidat, Sönke; Prévôt, André S. H.

    2017-03-01

    Equivalent black carbon (EBC) measured by a multi-wavelength Aethalometer can be apportioned to traffic and wood burning. The method is based on the differences in the dependence of aerosol absorption on the wavelength of light used to investigate the sample, parameterized by the source-specific absorption Ångström exponent (α). While the spectral dependence (defined as α values) of the traffic-related EBC light absorption is low, wood smoke particles feature enhanced light absorption in the blue and near ultraviolet. Source apportionment results using this methodology are hence strongly dependent on the α values assumed for both types of emissions: traffic αTR, and wood burning αWB. Most studies use a single αTR and αWB pair in the Aethalometer model, derived from previous work. However, an accurate determination of the source specific α values is currently lacking and in some recent publications the applicability of the Aethalometer model was questioned.Here we present an indirect methodology for the determination of αWB and αTR by comparing the source apportionment of EBC using the Aethalometer model with 14C measurements of the EC fraction on 16 to 40 h filter samples from several locations and campaigns across Switzerland during 2005-2012, mainly in winter. The data obtained at eight stations with different source characteristics also enabled the evaluation of the performance and the uncertainties of the Aethalometer model in different environments. The best combination of αTR and αWB (0.9 and 1.68, respectively) was obtained by fitting the Aethalometer model outputs (calculated with the absorption coefficients at 470 and 950 nm) against the fossil fraction of EC (ECF / EC) derived from 14C measurements. Aethalometer and 14C source apportionment results are well correlated (r = 0.81) and the fitting residuals exhibit only a minor positive bias of 1.6 % and an average precision of 9.3 %. This indicates that the Aethalometer model reproduces

  14. Complicações obstétricas, eventos estressantes, violência e depressão durante a gravidez em adolescentes atendidas em unidade básica de saúde Obstetric complications, stressful life events, violence and depression during pregnancy in adolescents at primary care setting

    Directory of Open Access Journals (Sweden)

    Priscila Krauss Pereira

    2010-01-01

    Full Text Available CONTEXTO: A depressão é um transtorno psiquiátrico comum entre as adolescentes grávidas e está associada a diversos fatores de risco. OBJETIVOS: Estimar a prevalência da depressão em adolescentes grávidas e identificar os principais fatores de risco. MÉTODOS: Dados seccionais foram coletados de 120 gestantes adolescentes atendidas em uma unidade básica de saúde do Rio de Janeiro. Os instrumentos utilizados foram o Composite International Diagnostic Interview (CIDI, para diagnosticar a depressão; a escala Stressful Life Events, para avaliar a presença de eventos estressantes; o Abuse Assessment Screen (AAS, para o rastreamento de violência contra a mulher durante a gestação. RESULTADOS: A prevalência de depressão gestacional foi de 14,2% (IC: 8,7-21,9, sendo os principais fatores associados: história anterior de depressão, sangramento anômalo e hospitalização na atual gravidez, história de acidente, incêndio ou catástrofe e maus-tratos durante a vida. CONCLUSÕES: Os resultados reforçam que a investigação dos fatores de risco, o diagnóstico e o tratamento da depressão devem ser parte integrante do atendimento pré-natal a adolescentes grávidas.BACKGROUND: Depression is a common psychiatric disorder among pregnant adolescents and it is associated with several risk factors. OBJECTIVES: This study aimed to assess the prevalence and associated factors of depression in pregnant adolescents. METHODS: Sectional data were collected among 120 pregnant adolescents attending in a basic health unit in Rio de Janeiro. The following research instruments were used: the Composite International Diagnostic Interview (CIDI to diagnose depression, the Stressful Life Events to assess stressful life events, the Abuse Assessment Screen (AAS to screening violence against woman during pregnancy. RESULTS: The prevalence of gestational depression was 14.2% (CI 95% 8.7-21.9 and associated factors were: history of depression before pregnancy

  15. TeraHertz imaging of hidden paint layers on canvas

    NARCIS (Netherlands)

    Adam, A.J.L.; Planken, P.C.M.; Meloni, S.; Dik, J.

    2009-01-01

    We show terahertz reflection images of hidden paint layers in a painting on canvas and compare the results with X-ray Radiography and Infrared Reflectography. Our terahertz measurements show strong reflections from both the canvas/paint interface and from the raw umber/lead white interface,

  16. One hertz seismic attenuation for low frequency gravitational waves interferometers

    Energy Technology Data Exchange (ETDEWEB)

    Mantovani, Maddalena [Universita di Siena Via Roma 56-53100 Siena (Italy)]. E-mail: mantovan@ego-gw.it; DeSalvo, Riccardo [California Institute of Technology 18-34, Pasadena, CA 91125 (United States)

    2005-12-01

    This article describes a mechanical vertical attenuation system capable to provide large attenuation factors above 1Hz. This system is derived from, and improves, the passive Geometric Anti-Spring seismic attenuation filters minimizing their vertical resonant frequency by means of a tunable electromagnetic spring mounted in parallel with the main spring. The tunable spring is also used to compensate thermal drift in the new arrangement. We found an unexplained deviation from the 1/f{sup 2} transfer function at resonant frequencies below {approx}100mHz.

  17. Measured losses in superconductor magnets for 60-Hertz ac operation.

    Science.gov (United States)

    Hamlet, I. L.; Kilgore, R. A.

    1971-01-01

    Results of an experimental study of electrical losses in superconductor magnets. Preliminary 60-Hz ac loss data are presented for coils constructed of Nb3Sn ribbon, Nb-Ti cable, and multifilament Nb-Ti. Losses have been measured for different size coils up to approximately 20 cm in diameter. Of the conductor types tested, Nb3Sn ribbon has the lowest losses for ac operation. In Nb3Sn-ribbon coils of different sizes, the loss per unit length of conductor is shown to decrease with a decrease in the rate of change of current and to increase, in general, with increase in coil size. An important aspect of the study is the high degree of repeatability of the data.

  18. Measurement of instrument noise spectra at frequencies below 1 hertz

    Science.gov (United States)

    Snare, R. C.; Mcpherron, R. L.

    1973-01-01

    The use of peak-to-peak values in describing output noise of a magnetometer or low frequency amplifier is of questionable value for certain applications. A more precise statement of instrument noise is made with a plot of the noise power spectral density vs frequency. The spectral density plot provides a rich source of information which can be used in the selection and testing of such instrumentation.

  19. The 400-Hertz constant-speed electrical generation systems

    Science.gov (United States)

    Mcclung, R.

    1982-01-01

    Materials illustrating a presentation on 400 Hz constant speed generation systems are presented. The system features are outlined, components and functioning described, and display graphics illustrated.

  20. Calculations for Tera-Hertz (THZ) Radiation Sources

    CERN Document Server

    Spencer, James

    2005-01-01

    We explore possibilities for THz sources from 0.3 - 30 THz. While still inaccessible, this broad gap is even wider for advanced acceleration schemes extending from X or, at most, W band RF at the low end up to CO2 lasers. While the physical implementations of these two approaches are quite different, both are proving difficult to develop so that even lower frequency, superconducting RF seems to be the currently preferred means. Similarly, the validity of modelling techniques varies greatly over this range of frequencies but generally mandates coupling Maxwell’s equations to the appropriate device transport physics for which there are many options. Here we calculate radiation from shaped transmission lines using finite-difference, time-domain (FDTD) simulations of Maxwell’s equations coupled to Monte-Carlo techniques for both the production and transport physics of short electron pulses. Examples of THz sources that demonstrate coherent interference effects will be discussed with the goal o...

  1. Optical Displacement Sensor for Sub-Hertz Applications

    Science.gov (United States)

    Abramovici, Alexander; Chiao, Meng P.; Dekens, Frank G.

    2008-01-01

    A document discusses a sensor made from off-the-shelf electro-optical photodiodes and electronics that achieves 20 nm/(Hz)(exp 1/2) displacement sensitivity at 1 mHz. This innovation was created using a fiber-coupled laser diode (or Nd:YAG) through a collimator and an aperture as the illumination source. Together with a germanium quad photodiode, the above-mentioned displacement sensor sensitivities have been achieved. This system was designed to aid the Laser Interferometer Space Antenna (LISA) with microthruster tests and to be a backup sensor for monitoring the relative position between a proof mass and a spacecraft for drag-free navigation. The optical displacement sensor can be used to monitor any small displacement from a remote location with minimal invasion on the system.

  2. Crecimiento Personal, Necesidad de Trascendencia, Redes Sociales y Ambiente: análisis de la Calidad de Vida Percibida en diferentes sucesos estresantes desde un enfoque integrativo y ecológico Personal Growth, Transcendence Needs, Social Networks and Environment: A study of Perceived Quality of Life related with different life stressful life events from an integrative and ecological aproach

    Directory of Open Access Journals (Sweden)

    Isabel María Mikulic

    2007-12-01

    Full Text Available La evaluación de la Calidad de Vida Percibida por los sujetos que afrontan sucesos estresantes tales como encarcelamiento, discapacidad, divorcio, pérdidas de familiares o migración forzada, no ha concitado la especial atención de los investigadores. Si bien no existe consenso en cuanto a la definición de Calidad de Vida y su operacionalización, está aceptado el carácter multidimensional de este constructo. En anteriores investigaciones (Mikulic, Muiños, 2005 se ha presentado la construcción y validación de un Inventario de Calidad de Vida Percibida con el que se ha podido verificar la estructura factorial de dicho constructo aplicando el Modelo de Ecuaciones Estructurales. Los factores hallados ambiente, redes sociales, crecimiento personal y necesidad de trascendencia han podido ser explicados adecuadamente por un solo concepto: Calidad de Vida Percibida. El objetivo de este trabajo es mostrar la existencia y magnitud de dichos factores latentes encontrados en quienes atraviesan dichos sucesos estresantes analizados con dicho instrumento.Perceived quality of life assessment of persons undergoing stressful life events such as imprisonment, diseases, divorce, close relatives loss or forced migration, has received relatively little attention in the literature. Athough there is no consensus on the definition of QOL and its measurement, it is generally accepted that QOL is a multidimiensional construct. In previous studies (Mikulic, Muiños, 2004 it has been showed PQOL Inventory design and validation and 0SEM applied to verify factorial structure. The Second- Order CFA suggested that QOL may be measured by five underlying factors: environment, social networks, personal growth and transcedence needs. The aim of this study is to estimate the existence and magnitude of the latent identified factors in the quality of life perceived by participants undergoing different stressful life events.

  3. Inferring wavelength dependence of AOD and Ångström exponent over a sub-tropical station in South Africa using AERONET data: influence of meteorology, long-range transport and curvature effect.

    Science.gov (United States)

    Kumar, K Raghavendra; Sivakumar, V; Reddy, R R; Gopal, K Rama; Adesina, A Joseph

    2013-09-01

    Aerosol optical properties over a southern sub-tropical site Skukuza, South Africa were studied to determine the variability of the aerosol characteristics using CIMEL Sunphotometer data as part of the AErosol RObotic NETwork (AERONET) from December 2005 to November 2006. Aerosol optical depth (AOD), Ångström exponent (α), and columnar water vapor (CWV) data were collected, analyzed, and compiled. Participating in this network provided a unique opportunity for understanding the sources of aerosols affecting the atmosphere of South Africa (SA) and the regional radiation budget. The meteorological patterns significantly (p1 μm). Trajectory cluster analyses revealed that the air masses during the autumn and winter seasons have longer advection pathways, passing over the ocean and continent. This is reflected in the aerosol properties that are derived from the ocean, desert, and anthropogenic activities that include biomass burning and industrial pollution. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Distortion Exponent in MIMO Channels with Feedback

    CERN Document Server

    Gunduz, Deniz; Poor, H Vincent

    2009-01-01

    The transmission of a Gaussian source over a block-fading multiple antenna channel in the presence of a feedback link is considered. The feedback link is assumed to be an error and delay free link of capacity 1 bit per channel use. Under the short-term power constraint, the optimal exponential behavior of the end-to-end average distortion is characterized for all source-channel bandwidth ratios. It is shown that the optimal transmission strategy is successive refinement source coding followed by progressive transmission over the channel, in which the channel block is allocated dynamically among the layers based on the channel state using the feedback link as an instantaneous automatic repeat request (ARQ) signal.

  5. The Response Inventory for Stressful Life Events (RISLE) I ...

    African Journals Online (AJOL)

    Background: No indigenous screening instruments are available for the detection of depression and suicide risk relevant to the context of patients in Uganda. ... Methods: Two samples were used in the validation exercise: a general population sample from Adjumani and Bugiri districts and a student sample from Makerere ...

  6. Stressful life events in pregnancy and head circumference at birth

    DEFF Research Database (Denmark)

    Obel, Carsten; Hedegaard, Morten; Henriksen, Tine Brink

    2003-01-01

    A strong association between stress in pregnancy and small head circumference in infants at birth was reported in 1994. This important finding has never been replicated. In a follow-up study of 4211 participants with singleton pregnancies, information on life events was collected twice during...... pregnancy and head circumference measured shortly after birth following standard procedures. No association was found between experienced or perceived stress as a result of life events during pregnancy and head circumference in the infants. In conclusion, stress in pregnancy may influence foetal brain...

  7. The Response Inventory for Stressful Life Events (RISLE) II ...

    African Journals Online (AJOL)

    Objective: To compare the responses of the 36-item RISLE to interview derived psychiatric diagnoses and suicidal ideation in a sub-sample of the general population and student samples reported in the accompanying paper. Methods: Clinical interviews using the Mini International Neuropsychiatric Interview (MINI) were ...

  8. Timpanometria com sonda de 226 e 1000 hertz em bebês Tympanometry with 226 and 1000 hertz tone probes in infants

    Directory of Open Access Journals (Sweden)

    Luciana Macedo de Resende

    2012-02-01

    Full Text Available Os objetivos deste estudo foram descrever e analisar as medidas timpanométricas obtidas com sonda de 226 e 1000 Hz; verificar correlação da timpanometria com o resultado das emissões otoacústicas e otoscopia; descrever as alterações. MATERIAL E MÉTODO: Estudo prospectivo, duplo cego, realizado com 70 bebês, entre 7 dias e 1 mês e 13 dias de vida. Foram realizadas as emissões otoacústicas, otoscopia e timpanometria com sonda de 226 Hz e 1000 Hz. RESULTADOS: Observou-se diferença estatisticamente significante (pThis study aimed at describing and analyzing tympanometric results obtained with 226Hz and 1000Hz probe tones; checking for correlations between tympanometry, otoacoustic emissions and otoscopic examination; describing abnormal results found in the evaluation procedures. METHODS: Double-blind and prospective study. Our sample included 70 babies, between 7 days and one month and 13 days of age, without risk indicators for hearing loss, evaluated in the State Neonatal Hearing Screening Program. Transient evoked otoacoustic emissions, otoscopic examination and tympanometry with 226Hz and 1000Hz probe tones were used as assessment tools. The study was approved by the Ethics Committee from the institution. RESULTS: Statistically significant differences were observed (p<0.05 in the tympanometric measures correlation and also between transient evoked otoacoustic emissions and compliance obtained with both probe tones. Most test results were within the normal range (94.28%. Three children (4.28% were referred to diagnostic follow-up and one (1.42% had middle ear dysfunction confirmed by otoscopy and 1000Hz tympanometry. CONCLUSIONS: 1000Hz tympanometry is the most reliable probe tone used to evaluate children under three months of age. More studies focusing on middle ear acoustics and mechanics are necessary to provide reliable and precise interpretation in the evaluation of middle ear functions in babies.

  9. Eventos de vida produtores de estresse e queixas de insônia entre auxiliares de enfermagem de um hospital universitário no Rio de Janeiro: estudo Pró-Saúde Stressful life events and insomnia complaints among nursing assistants from a university hospital in Rio de Janeiro: the Pro-Saude study

    Directory of Open Access Journals (Sweden)

    Jaqueline R. Robaina

    2009-09-01

    Full Text Available OBJETIVO: Avaliar a associação entre eventos de vida produtores de estresse (EVPE e queixas de insônia (QI. MÉTODOS: Foram analisados dados seccionais de 695 auxiliares de enfermagem de um hospital universitário, participantes do Estudo Pró-Saúde - coorte de funcionários de uma universidade no Rio de Janeiro. As informações foram obtidas através de um questionário multidimensional e autopreenchido, que avaliou a ocorrência de EVPE nos últimos 12 meses, variáveis socioeconômicas e demográficas e QI. As QI foram analisadas como desfecho politômico (frequente, ocasional, e ausente. Odds ratios brutos e ajustados foram calculados através de regressão logística multinomial. RESULTADOS: A prevalência total de QI foi de 45,8% (16,7% frequentes e 29,1% ocasionais. Após ajuste por sexo, idade, estado civil, renda familiar per capita e regime de trabalho, os EVPE associados com QI frequentes foram: "rompimento de relação amorosa" (OR = 3,32; IC95% 1,90 - 5,78, "ter tido problemas graves de saúde" (OR = 2,82; IC95% 1,73 - 4,58; "dificuldades financeiras graves" (OR = 2,38; IC95% 1,46 - 3,88, e "mudança forçada de moradia" (OR = 1,97; IC95% 1,02 - 3,79. Com relação às QI ocasionais, houve associação apenas com rompimento de relação amorosa (OR = 2,30; IC95% 1,42 - 3,74 e dificuldades financeiras graves (OR = 1,87; IC95% 1,27 - 2,75. CONCLUSÕES: Dada a responsabilidade com vidas humanas que os auxiliares de enfermagem assumem durante seu horário de trabalho, nossos achados podem contribuir para ações mais efetivas, por parte dos serviços de saúde ao trabalhador, para lidar com o estresse nessa categoria.OBJECTIVE: To evaluate the association between stressful life events (SLE and insomnia complaints (IC. METHODS: Cross-sectional data from 695 certified nursing assistants from a university hospital, participants of the Pro-Saude Study - a cohort of university employees in Rio de Janeiro, were analyzed. Information was

  10. Phase diagram of Hertzian spheres

    NARCIS (Netherlands)

    Pàmies, J.C.; Cacciuto, A.; Frenkel, D.

    2009-01-01

    We report the phase diagram of interpenetrating Hertzian spheres. The Hertz potential is purely repulsive, bounded at zero separation, and decreases monotonically as a power law with exponent 5/2, vanishing at the overlapping threshold. This simple functional describes the elastic interaction of

  11. Existence of solutions for elliptic systems with critical Sobolev exponent

    Directory of Open Access Journals (Sweden)

    Pablo Amster

    2002-06-01

    Full Text Available We establish conditions for existence and for nonexistence of nontrivial solutions to an elliptic system of partial differential equations. This system is of gradient type and has a nonlinearity with critical growth.

  12. Was Aristotle an Exponent of Antiscientific Mumbo-Jumbo?

    Science.gov (United States)

    Koznjak, Boris

    2012-01-01

    During the past few decades, a wide consensus has been reached in the community of science educators that it is almost unimaginable to conduct a quality science education without including the history and philosophy of science in some form in the science curriculum, and this is especially the case for physics education (Matthews 1994). However, in…

  13. On error probability exponents of many hypotheses optimal testing illustrations

    OpenAIRE

    Navaei, Leader

    2011-01-01

    In this paper we study a model of hypotheses testing consisting of with to simple homogeneous stationary Markov chains ith finite number of states such that having different distributions from four possible transmission probabilities. For solving this problem we apply the method of type and large deviation techniques (LTD). The case of two objects having different distributions from to given probability distribution as examined by Ahlswedeh and Haroutunian.

  14. On error probability exponents of many hypotheses optimal testing ...

    African Journals Online (AJOL)

    In this paper we study a model of hypotheses testing consisting of with to simple homogeneous stationary Markov chains ith finite number of states such that having different distributions from four possible transmission probabilities.For solving this problem we apply the method of type and large deviation techniques (LTD).

  15. Sample and population exponents of generalized Taylor’s law

    Czech Academy of Sciences Publication Activity Database

    Giometto, A.; Formentin, Marco; Rinaldo, A.; Cohen, J.; Maritan, A.

    2015-01-01

    Roč. 112, č. 25 (2015), s. 7755-7760 ISSN 0027-8424 R&D Projects: GA ČR GAP201/12/2613 Institutional support: RVO:67985556 Keywords : fluctuation scaling * multiplicative growth * power law * environmental stochasticity * Markovian environment Subject RIV: BA - General Mathematics Impact factor: 9.423, year: 2015 http://library.utia.cas.cz/separaty/2015/SI/formentin-0444162.pdf

  16. On critical exponent for the existence and stability properties of ...

    Indian Academy of Sciences (India)

    pseudoplastics. If (p,q) = (2, 2), they are Newtonian fluids. When c = 0, systems of the form (1)–(3) arise in several context in biology and engi- neering (see [10]). It provides a simple model to describe, for instance, the interaction of three diffusing biological species. u,v and w represent the densities of three species. See [11] ...

  17. Dynamic dilution exponent in monodisperse entangled polymer solutions

    DEFF Research Database (Denmark)

    Shahid, T.; Huang, Qian; Oosterlinck, F.

    2017-01-01

    We study and model the linear viscoelastic properties of several entangled semi-dilute and concentrated solutions of linear chains of different molar masses and at different concentrations dissolved in their oligomers. We discuss the dilution effect of the oligomers on the entangled long chains. ......-molecule theta or good solvents. Possible explanations for the differences between these sample sets are proposed, based on the comparison of their viscoelastic behavior....

  18. determination of the power law exponent for southern highlands of ...

    African Journals Online (AJOL)

    Mgina

    The 1/7th power law is among the methods that have been used to extrapolate wind speed to the hub heights of wind turbines from the measuring ... surfaces compared to smooth surfaces. At low wind speeds the change in speed with ... stages of prospecting wind energy potential at a site, it may suffice to use the power law.

  19. Lexical exponents of hypothetical modality in Polish and Lithuanian

    Directory of Open Access Journals (Sweden)

    Roman Roszko

    2015-11-01

    To analyse both the languages there is used the method of theoretical contrastive studies, which the most important features are: (1 orienting the studies from the content grounds to the formal grounds, (2 using a semantic interlanguage as tertium comparationis. First of all, the content of hypothetical modality and its definition and paraphrase is given here. Next, the gradational character of this category is discussed. There are distinguished six groups of lexemes expressing the corresponding degrees of hypothetical modality — from a shadow of uncertainty (minimal degree of probability to an almost complete certainty (maximum degree of probability. The experimental Polish-Lithuanian corpus is widely applied in the studies.

  20. IFIC expone grandes piezas del acelerador particulas de Ginebra

    CERN Multimedia

    2005-01-01

    The Institute for corpuscular physics of Valencia University exhibits from today great pieces coming from the particle accelerator of CERN in Geneva, an underground laboratory of high technologic level producing small atomic particles which it makes collide at very high energies to study the fundamental components of the matter and its interactions (1 page)

  1. Higgs Critical Exponents and Conformal Bootstrap in Four Dimensions

    DEFF Research Database (Denmark)

    Antipin, Oleg; Mølgaard, Esben; Sannino, Francesco

    2015-01-01

    interactions, but differ by developing perturbative interacting fixed points. We investigate the physical properties of the singlet and the adjoint composite operators quadratic in the Higgs field, and discover that the singlet anomalous dimension is substantially larger than the adjoint one. The numerical...

  2. Investigation of power law wind exponent within the lower boundary ...

    African Journals Online (AJOL)

    -storey building at the Department of Physics, Obafemi Awolowo University Ile-Ife, Nigeria (7.520 N and 4.520 E), 294 m height above mean sea level and about 20 m above the ground level has been used to study on continuous basis the ...

  3. Error exponents for quantum channels with constrained inputs

    Science.gov (United States)

    Holevo, A. S.; Sohma, M.; Hirota, O.

    2000-12-01

    The purpose of this work is the study of the error probability for quantum channels with infinite (continuous) alphabets and additive constraints onto the input signal. We derive the lower bounds for the reliability function of such channels in terms of quantum Gallager's functions and compute them for quantum Gaussian channels.

  4. Higgs critical exponents and conformal bootstrap in four dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Antipin, Oleg [INFN, Sezione di Firenze,Via G. Sansone 1, I-50019 Sesto Fiorentino (Italy); Mølgaard, Esben; Sannino, Francesco [CP-Origins & the Danish Institute for Advanced Study Danish IAS,University of Southern Denmark,Campusvej 55, DK-5230 Odense M (Denmark)

    2015-06-04

    We investigate relevant properties of composite operators emerging in nonsupersymmetric, four-dimensional gauge-Yukawa theories with interacting conformal fixed points within a precise framework. The theories investigated in this work are structurally similar to the standard model of particle interactions, but differ by developing perturbative interacting fixed points. We investigate the physical properties of the singlet and the adjoint composite operators quadratic in the Higgs field, and discover, via a direct computation, that the singlet anomalous dimension is substantially larger than the adjoint one. The numerical bootstrap results are, when possible, compared to our precise findings associated to the four dimensional conformal field theoretical results. To accomplish this, it was necessary to calculate explicitly the crossing symmetry relations for the global symmetry group SU(N)×SU(N).

  5. GUSTO: Gal/Xgal U/LDB Spectroscopic-Stratospheric TeraHertz Observatory

    Science.gov (United States)

    Kidd Walker, Christopher; Kulesa, Craig; Goldsmith, Paul; Groppi, Christopher; Helmich, Frank; Hollenbach, David; Kawamura, Jonathan; Langer, William; Melnick, Gary; Neufeld, David; Pineda, Jorge; Stacey, Gordon; Stark, Antony; Tielens, Alexander; Wolfire, Mark; Yorke, Harold; Young, Erick

    2018-01-01

    GUSTO is a recently selected NASA Explorer mission that will map in unprecedented detail the structure, dynamics, energy balance, and evolution of the interstellar medium within the Milky Way and Large Magellanic Cloud. GUSTO is a balloon-borne, 0.85-m on-axis telescope that will observe in three important interstellar lines: [CII], [OI], and [NII] at 158, 63, and 205 microns, respectively. With its 60" angular resolution, high-velocity resolution, and efficient “On-The-Fly” mapping strategy, GUSTO will address key unanswered questions about the stellar life cycle and provide new insights into the birth and evolution of stars and galaxies. From its Ultra-Long-Duration Balloon (ULDB) platform at an altitude of 33 km, GUSTO will survey ~100 deg2 of the Milky Way and 24 deg2 of the LMC at 60" angular resolution using three 8-pixel heterodyne array receivers. The GUSTO receivers provide sub-km/s velocity resolution and bandwidths sufficiently wide to track all clouds orbiting in the Milky Way and LMC. GUSTO will detect and locate in three dimensions every important interstellar cloud (AV > 0.5–1) in the surveyed regions. The baseline mission of 100 days can be completed in one ULDB Antarctic balloon flight, and an extended mission of up to 169 days is possible. GUSTO’s observing campaign comprises three distinct surveys: GPS: A Galactic Plane Survey (42 days); LMCS: An LMC Survey (36 days); TDS: Targeted Deep Surveys of selected regions in the Galaxy and LMC (18 days). In our presentation we will discuss both the science goals of GUSTO and the mission implementation.

  6. Single-stage electrohydraulic servosystem for actuating on airflow valve with frequencies to 500 hertz

    Science.gov (United States)

    Webb, J. A., Jr.; Mehmed, O.; Lorenzo, C. F.

    1980-01-01

    An airflow valve and its electrohydraulic actuation servosystem are described. The servosystem uses a high-power, single-stage servovalve to obtain a dynamic response beyond that of systems designed with conventional two-stage servovalves. The electrohydraulic servosystem is analyzed and the limitations imposed on system performance by such nonlinearities as signal saturations and power limitations are discussed. Descriptions of the mechanical design concepts and developmental considerations are included. Dynamic data, in the form of sweep-frequency test results, are presented and comparison with analytical results obtained with an analog computer model is made.

  7. Stress concentration in periodically rough Hertzian contact: Hertz to soft-flat-punch transition.

    Science.gov (United States)

    Ledesma-Alonso, R; Raphaël, E; Léger, L; Restagno, F; Poulard, C

    2016-09-01

    We report on the elastic contact between a spherical lens and a patterned substrate, composed of a hexagonal lattice of cylindrical pillars. The stress field and the size of the contact area are obtained by means of numerical methods: a superposition method of discrete pressure elements and an iterative bisection-like method. For small indentations, a transition from a Hertzian to a soft-flat-punch behaviour is observed when the surface fraction of the substrate that is covered by the pillars is increased. In particular, we present a master curve defined by two dimensionless parameters, which allows one to predict the stress at the centre of the contact region in terms of the surface fraction occupied by pillars. The transition between the limiting contact regimes, Hertzian and soft-flat-punch, is well described by a rational function. Additionally, a simple model to describe the Boussinesq-Cerruti-like contact between the lens and a single elastic pillar, which takes into account the pillar geometry and the elastic properties of the two bodies, is presented.

  8. ULF waves upstream of the Venus bow shock - Properties of one-hertz waves

    Science.gov (United States)

    Orlowski, D. S.; Russell, C. T.

    1991-01-01

    Pioneer Venus Orbiter data are used here to study the properties of a class of ULF upstream waves with relatively high observed frequencies. These waves show significant similarity to 'one-Hz' waves identified at earth in the ISEE 1 and 2 observations and the whistler waves identified earlier by IMP 6 observations. The waves appear almost immediately after the spacecraft crosses the magnetic field tangent line to the bow shock surface into the region of connected field lines. The wave amplitude decreases with distance from the shock measured along the magnetic field line. Group velocities calculated using the cold plasma dispersion relation indicate that the waves have sufficient upstream velocities to propagate form the shock into the solar wind. The totality of observations seem best explained by a source of right-handed whistler mode waves at the bow shock.

  9. Eight to Twelve Hertz Occipital EEG Training with Moderate and Severely Retarded Epileptic Individuals.

    Science.gov (United States)

    Rudrud, Eric; Striefel, Sebastian

    1981-01-01

    Three retarded epileptic individuals (17 to 22 years old) with a variety of seizure disorders were provided with 8 to 12 Hz occipital EEG biofeedback training. While seizures were not totally eliminated in any of the Ss, the results of the study indicated that all Ss exhibited decreases in some aspect of their seizure activity. (Author)

  10. Upstream waves at Mercury, Venus and earth - Comparison of the properties of one Hertz waves

    Science.gov (United States)

    Orlowski, D. S.; Crawford, G. K.; Russell, C. T.

    1990-01-01

    Previous studies have shown that the Venus foreshock region contains low-frequency upstream waves similar to those in the terrestrial foreshock, but perhaps with different amplitudes than at earth. This paper compares the properties of a second class of upstream waves, analogous to the so-called 1 Hz waves at earth. The waves observed at Mercury, Venus, and earth have very similar properties, i.e., propagation angles less than 55 degrees to the magnetic field and less than 35 degrees to the solar wind flow direction. The waves occur exclusively on the field lines connected to the bow shock. They are most commonly left-hand elliptically polarized with similar fractional amplitudes, approximately 0.1 of the background field strength. Their amplitudes decrease with increasing distance from the shock. The observed frequencies are similar for Mercury, Venus, and earth when scaled by the interplanetary magnetic field. If, as generally assumed at earth, these waves arise in regions of backstreaming electrons, these results imply that similar electron foreshocks occur at earth, Venus and Mercury despite differences in bow shock size and the nature of the obstacle to the solar wind.

  11. Propagation Loss Measurements at 400 Hertz in the BIFI Range Using a Towed Source.

    Science.gov (United States)

    1971-01-27

    series using the BIFI Range (Reference 1) located between Block Island, Rhode Island and Fishers Island, New York. Three types of acoustic tests were... Colossus theoretical predictions (Reference 7). The agreement is fairly good; it is apparent, howev er, that the Colossus predictions do not take into...given in reference 11. - Propagation loss was measured as a function of range and the results compared to the Colossus predictions’ (reference 7). The

  12. 35-45 Giga Hertz Transceiver System for Phase and Magnitude Detection

    Science.gov (United States)

    Beni, Aman Aflaki

    2007-01-01

    Nondestructive evaluation (NDE) is the science and practice of examining an object in a way that the object's usefulness is not adversely affected. Different types of NDE methods exist but this thesis is based on microwave and millimeter wave NDE using imaging techniques. Microwave NDE is based on illuminating the object under test with a microwave signal and studying the various properties of the reflected signal from the object. This reflected signal contains some information about the inner structure of the object under test. This information may be contained in several parameters including the phase and magnitude of the reflected signal. The goal of this project is to design and build a Q-band coherent transceiver that is capable of measuring the reflected signal's phase and magnitude so that an image of the object under test may be reconstructed. From the several techniques that can be used to construct an image of the object under test, techniques of interest to this work include synthetic aperture focusing technique (SAFT) and microwave holography. The transceiver system should have the ability to sweep a large portion of Q-band frequency range in small frequency steps as quick as possible while the detected phase and magnitude of the reflected signal is very accurate. Several different designs were studied and the final schematic diagram of the transceiver system was determined. One of the most important modules that was designed, implemented and tested in the laboratory was an accurate phase/magnitude detector circuit. The compared results of the scans using the transceiver system and vector network analyzer (VNA) showed that this transceiver system has a great potential to replace a VNA for the purpose of microwave and millimeter wave imaging.

  13. Characteristics of low vapor pressure oil ignition developed with irradiation of mega hertz level ultrasonic

    Energy Technology Data Exchange (ETDEWEB)

    Takuya Fuse; Yasuki Hirota; Noriyuki Kobayashi; Masanobu Hasatani; Yoshio Tanaka [Nagoya University, Nagoya (Japan). Department of Energy Engineering and Science

    2004-11-01

    In liquid fuel vaporizing type combustor for civil use, large amount of the electric power is consumed in pre-heating of fuel vaporizer during a standby period. Reduction of consumed power in pre-heating is regarded as important to develop a performance of the vaporizing type combustor from the viewpoint of energy saving. We proposed the oil combustion system using the MHz-ultrasonic atomizing method without the preheating process. In this work, we manufactured kerosene pre-vaporizing combustor with ultrasonic oscillator which had frequency of 1.7 MHz. Low CO and NOx emission had been already achieved with manufactured combustor by authors in 2002. Aiming to investigate fundamental characteristics of the ignition process with ultrasonic atomizing, the ignition time requirement was measured and the flame luminescence was detected with spectroscopic analysis in order to consider the mixing state on pre-mixing combustor by judging differences of the flame luminescence. As the results, ultrasonic atomizing method was very effective for vaporization of kerosene. But heat release rate of only 0.54 kW was obtained with input power of 33 W because the effect of the sound absorption was not negligible. The time requirement for the ignition was influenced by an equivalence ratio and balance between primary air flow rate and secondary one. Especially, the ignition time had different tendencies between fuel rich and fuel lean condition. With flow visualization, it was clarified that probability of the ignition depended on a difference of flow pattern of the fuel aerosol. 17 refs., 12 figs., 1 tab.

  14. Gender, active education, language and nation in the Basque Country. Julene Azpeitia (1888-1980, exponent of a budding Basque education Género, educación activa, lengua y nación en el País Vasco. Julene Azpeitia (1888-1980, exponente de una educación vasca en ciernes

    Directory of Open Access Journals (Sweden)

    Idoia FERNÁNDEZ FERNÁNDEZ

    2013-02-01

    Full Text Available The biographical approach by J. J. de la Granja and G. Arrien (1988 is our main basis for further analysis about the articles of Julene Azpeitia, the Basque teacher and writer. So can we also interpret her thoughts about education, taking into account some variables such as gender, nation, language and new pedagogy. This work is intended to support the idea that the gender, educational and political ideology of the Basque nationalist women in the pre-war thirties, among whom Julene Azpeitia was a significant exponent, must be understood within the bourgeois ideology of European nation-states —and the contradictions that happened in a stateless nation. In order to demonstrate so we have analysed her journalistic and pedagogical writings, and approached them as a case study. This study has been completed with some videotaped in-depth interviews to significant nationalist women from the Republican period.El acercamiento biográfico realizado por J. J. de la Granja y G. Arrien (1988 en torno a la maestra y escritora Julene Azpeitia nos sirve de base para profundizar en el análisis de sus numerosos artículos e interpretar su pensamiento pedagógico atendiendo a variables como el género, la nación, la lengua y a la pedagogía nueva. El trabajo pretende sustentar la tesis de que la ideología política, genérica y educativa de las mujeres nacionalistas vascas de preguerra, de quien Julene Azpeitia fue un significativo exponente, son partícipes de la ideología burguesa de los Estados-nación europeos con la diferencia de que en su caso esta ideología debía atemperarse con las contradicciones de una nación sin Estado. Para ello hemos analizado sus escritos periodísticos y pedagógicos, tratados como estudio de caso en un marco de investigación basado en entrevistas en profundidad grabadas en vídeo a significadas mujeres nacionalistas vascas del periodo republicano.

  15. An Investigation of the Relationship between Stressful Life Events and Psychological, Behavioral and Physiological Outcomes

    Science.gov (United States)

    1984-09-01

    life events were significantly related to ’ "decreased job satisfacion (Sarason & Johnson, 1979). An enlarged sample size, though, would be required...19 Background..................................20 Social Arrangement. . . . . . . . 21 Individual Differences ..... ...... 2 Job Demand...Organizational problems shown by research efforts to be affected by stress have included absenteeism, decreased productivity, turnover and job

  16. Psychological Distress and Stressful Life Events in Pediatric Complex Regional Pain Syndrome

    Directory of Open Access Journals (Sweden)

    Julia Wager

    2015-01-01

    Full Text Available BACKGROUND: There is little knowledge regarding the association between psychological factors and complex regional pain syndrome (CRPS in children. Specifically, it is not known which factors precipitate CRPS and which result from the ongoing painful disease.

  17. Stressful Life Events and the Tripartite Model: Relations to Anxiety and Depression in Adolescent Females

    Science.gov (United States)

    Fox, Jeremy K.; Halpern, Leslie F.; Ryan, Julie L.; Lowe, Kelly A.

    2010-01-01

    Although the tripartite model reliably distinguishes anxiety and depression in adolescents, it remains unclear how negative affectivity (NA) and positive affectivity (PA) influence developmental pathways to internalizing problems. Based on models which propose that affectivity shapes how youth react to stress, the present study attempted to…

  18. Work stress, life stress, and smoking among rural–urban migrant workers in China

    Directory of Open Access Journals (Sweden)

    Cui Xiaobo

    2012-11-01

    Full Text Available Abstract Background Stimulated by rapid modernization and industrialization, there is massive rural–urban migration in China. The migrants are highly susceptible to smoking and mental health problems. This study examined the association between both perceived work stress and perceived life stress with smoking behavior among this group during the period of migration. Methods Participants (n = 1,595 were identified through stratified, multi-stage, systematic sampling. Smoking status separated non-smokers from daily and occasional smokers, and migration history, work stress, and life stress were also measured. Analyses were conducted using the Chi-square test and multiple logistic regression. Two models were utilized. The first was the full model that comprised sociodemographic and migration-related characteristics, as well as the two stress variables. In addressing potential overlap between life and work stress, the second model eliminated one of the two stress variables as appropriate. Results Overall smoking prevalence was 64.9% (95% CI: 62.4-67.2%. In the regression analysis, under the full model, migrants with high perceived life stress showed a 45% excess likelihood to be current smokers relative to low-stress counterparts (OR: 1.45; 95% CI: 1.05 – 2.06. Applying the second model, which excluded the life stress variable, migrants with high perceived work stress had a 75% excess likelihood to be current smokers relative to opposites (OR: 1.75; 95% CI: 1.26–2.45. Conclusions Rural–urban migrant workers manifested a high prevalence of both life stress and work stress. While both forms of stress showed associations with current smoking, life stress appeared to outweigh the impact of work stress. Our findings could inform the design of tobacco control programs that would target Chinese rural–urban migrant workers as a special population.

  19. Stress, fatigue, and sleep quality leading up to and following a stressful life event

    NARCIS (Netherlands)

    Laethem, M. van; Beckers, D.G.J.; Dijksterhuis, A.J.; Geurts, S.A.E.

    2017-01-01

    This study aims to examine (a) the time course of stress, fatigue, and sleep quality among PhD students awaiting a stressful event and (b) whether daily anticipation of this event influences day-level stress, fatigue, and sleep quality. Forty-four PhD students completed evening and morning

  20. Stress, fatigue, and sleep quality leading up to and following a stressful life event.

    Science.gov (United States)

    Van Laethem, Michelle; Beckers, Debby G J; Dijksterhuis, Ap; Geurts, Sabine A E

    2017-10-01

    This study aims to examine (a) the time course of stress, fatigue, and sleep quality among PhD students awaiting a stressful event and (b) whether daily anticipation of this event influences day-level stress, fatigue, and sleep quality. Forty-four PhD students completed evening and morning questionnaires on eight days from 1 month before their dissertation defense until one month thereafter. Results showed increased stress leading up to the defense, while fatigue and sleep quality remained unchanged. Comparing the night before the defense with the night after, stress rapidly decreased, whereas fatigue and sleep quality increased. Following the defense, stress and sleep quality remained stable, whereas fatigue declined. Stress 1 month before the defense was higher than 1 month thereafter. Regarding day-level relations, stress was adversely affected by negative anticipation and favorably by positive outcome expectancy, whereas positive anticipation had no influence. Positive outcome expectancy was an important predictor of improved sleep quality. We conclude that stress may be elevated long before a stressful event takes place but that one can recover rather quickly from temporary stress. Positive outcome expectancy of a stressful event may be an important predictor of reduced day-level stress and improved day-level sleep quality leading up to a stressful event. Copyright © 2016 John Wiley & Sons, Ltd.

  1. Effects of stressful life events on cerebral white matter hyperintensity progression.

    Science.gov (United States)

    Johnson, Anne D; McQuoid, Douglas R; Steffens, David C; Payne, Martha E; Beyer, John L; Taylor, Warren D

    2017-12-01

    Exposure to stressful events is associated with both occurrence of depression and also vascular disease. The objective of this study was to determine whether higher levels of stress exposure was related to measures of pathological brain aging, specifically white matter hyperintensity volumes, in older adults with and without depression. The sample included 130 depressed and 110 never-depressed older adults aged 60 years or older enrolled in a longitudinal study at an academic medical center. Participants completed clinical assessments, assessment of stressful event exposure and perceived stress, and magnetic resonance imaging at baseline and after 2 years. Analyses examined both cross-sectional and longitudinal relationships between stress measures and white matter hyperintensity volumes. There were no statistically significant relationships observed between cross-sectional baseline stress measures and either baseline hyperintensity volume or 2-year change in hyperintensity volume. However, after controlling for demographic variables and baseline measures, change in stressor exposure was associated with change in hyperintensity volumes. In this analysis, increased stressor exposure was associated with greater increases in white matter hyperintensity volume, while reductions in stressor exposure were associated with less increase in hyperintensity volume. This relationship did not significantly differ based on the presence of either depression or medical comorbidities. This work adds to a growing literature associating exposure to stressful events in later life with more rapid pathological brain aging. Work is needed to understand the physiological mechanisms by which stress exposure has this effect and examine whether stress reduction techniques may modify these observed outcomes. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  2. Perceptions of stressful life events and depression: a test of attributional models.

    Science.gov (United States)

    Cochran, S D; Hammen, C L

    1985-06-01

    A brief review of tests of the attributional model of depression suggests that there is only weak or inconsistent support for the predicted causal ascriptions by depressed persons for negative events. Moreover, in very few studies have researchers actually tested the causal predictions of the model. Finally, because many of the studies were conducted with normal college students, the generality of the model as applied to different populations needs to be investigated. We addressed three questions: (a) the validity of the hypothesized independent and direction relation between each of the dimensions of internality, stability, controllability, intentionality, and globality and depression; (b) the causal relation between attributions and depression in a 2-month prospective study; and (c) evaluation of the model on two disparate samples: normal college students and elderly depressed outpatients ascribing causes for their personally stressful events. Causal modeling statistical procedures were applied to both the question of concurrent relations and causal relations between cognitions and depression. The results suggest minimal support for the attributional model: The dimensions were not each independently and directly associated with depression in the manner predicted by Abramson, Seligman, and Teasdale (1978), and the model that best fit the data was generally congruent for both the normal and clinical samples. In terms of direction of causality, the data were more consistent in indicating that depression causes cognitions than in indicating the reverse.

  3. Rumination predicts heightened responding to stressful life events in major depressive disorder and generalized anxiety disorder.

    Science.gov (United States)

    Ruscio, Ayelet Meron; Gentes, Emily L; Jones, Jason D; Hallion, Lauren S; Coleman, Elizabeth S; Swendsen, Joel

    2015-02-01

    Although studies have documented heightened stress sensitivity in major depressive disorder (MDD) and generalized anxiety disorder (GAD), the mechanisms involved are poorly understood. One possible mechanism is the tendency to ruminate in response to stress. We used ecological momentary assessment to study ruminative thoughts after stressful events in 145 adults with MDD, GAD, comorbid MDD-GAD, or no psychopathology. Diagnosed individuals reported more event-related rumination than controls, even after adjusting for event stressfulness. Rumination was equally common in MDD and GAD and was especially severe among comorbid cases. More rumination immediately after the event predicted poorer affect, more maladaptive behavior, and more MDD and GAD symptoms at the next signal, even when pre-event levels of these variables were controlled. Rumination mediated, but did not moderate, the association of stress with affect and with symptoms. Stress-related rumination was more deleterious for diagnosed than healthy individuals, more intense for more severe clinical cases, and more persistent for cases with a greater temperamental vulnerability for emotional disorders. These results implicate rumination as a mechanism of stress sensitivity and suggest pathways through which it may maintain depression and anxiety in everyday life. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

  4. Association of PER2 genotype and stressful life events with alcohol drinking in young adults.

    Directory of Open Access Journals (Sweden)

    Dorothea Blomeyer

    Full Text Available BACKGROUND: Clock genes govern circadian rhythms and shape the effect of alcohol use on the physiological system. Exposure to severe negative life events is related to both heavy drinking and disturbed circadian rhythmicity. The aim of this study was 1 to extend previous findings suggesting an association of a haplotype tagging single nucleotide polymorphism of PER2 gene with drinking patterns, and 2 to examine a possible role for an interaction of this gene with life stress in hazardous drinking. METHODS: Data were collected as part of an epidemiological cohort study on the outcome of early risk factors followed since birth. At age 19 years, 268 young adults (126 males, 142 females were genotyped for PER2 rs56013859 and were administered a 45-day alcohol timeline follow-back interview and the Alcohol Use Disorders Identification Test (AUDIT. Life stress was assessed as the number of severe negative life events during the past four years reported in a questionnaire and validated by interview. RESULTS: Individuals with the minor G allele of rs56013859 were found to be less engaged in alcohol use, drinking at only 72% of the days compared to homozygotes for the major A allele. Moreover, among regular drinkers, a gene x environment interaction emerged (p = .020. While no effects of genotype appeared under conditions of low stress, carriers of the G allele exhibited less hazardous drinking than those homozygous for the A allele when exposed to high stress. CONCLUSIONS: These findings may suggest a role of the circadian rhythm gene PER2 in both the drinking patterns of young adults and in moderating the impact of severe life stress on hazardous drinking in experienced alcohol users. However, in light of the likely burden of multiple tests, the nature of the measures used and the nominal evidence of interaction, replication is needed before drawing firm conclusions.

  5. Stressful life events and leukocyte telomere attrition in adulthood : a prospective population-based cohort study

    NARCIS (Netherlands)

    van Ockenburg, S. L.; Bos, E. H.; de Jonge, P.; van der Harst, P.; Gans, R. O. B.; Rosmalen, J. G. M.

    2015-01-01

    Background. Telomere attrition might be one of the mechanisms through which psychosocial stress leads to somatic disease. To date it is unknown if exposure to adverse life events in adulthood is associated with telomere shortening prospectively. In the current study we investigated whether life

  6. Attachment, Relationship Quality and Stressful Life Events: A Theoretical Meta-Perspective and Some Preliminary Results

    Directory of Open Access Journals (Sweden)

    Gidi Rubinstein

    2012-01-01

    Full Text Available La teoría del apego ha inspirado una explosión de investigación sobre el desarrollo de la personalidad, las relaciones íntimas y el complejo interjuego entre los procesos individuales y de relaciones en todas la fases de la vida. In los últimos años, la teoría ha sido ampliada al ámbito organizacional. A lo largo de tres décadas, la investigación sobre apego ha sido aplicada a las actitudes personales, el desempeño y las relaciones sociales en grandes organizaciones laborales, el ejército y grupos comunitarios. El presente articulo propone una perspectiva integrativa que uniría los aspectos psicológicos y sociológicos del apego.

  7. No interactions between genetic polymorphisms and stressful life events on outcome of antidepressant treatment

    DEFF Research Database (Denmark)

    Bukh, Jens Drachmann; Bock, Camilla; Vinberg, Maj

    2009-01-01

    in the genes encoding the serotonin transporter, brain derived neurotrophic factor, catechol-O-methyltransferase, angiotensin converting enzyme, tryptophan hydroxylase, and the serotonin receptors 1A, 2A, and 2C. We found no evidence that the effects of the genetic polymorphisms on treatment outcome were...

  8. Stressful life events are associated with insulin resistance among Chinese immigrant women in the United States

    Directory of Open Access Journals (Sweden)

    Carolyn Y. Fang

    2015-01-01

    Conclusions: This is one of the first studies to examine the associations between psychosocial stress and insulin resistance in Chinese immigrant women. These findings contribute to a growing body of literature on stress and diabetes risk in an immigrant population.

  9. School Reorientation of Children with Disabilities: A Stressful Life Event Challenging Parental Cognitive and Behavioral Adjustment

    Science.gov (United States)

    Roskam, Isabelle; Zech, Emmanuelle; Nils, Frederic; Nader-Grosbois, Nathalie

    2008-01-01

    The authors propose guidelines for counselors who notify parents of children with disabilities that a school reorientation is needed. They propose a model that integrates the predictors, moderators, and mediators of parental adjustment after school reorientation notification. The article includes the risk and resource factors associated with…

  10. Stressful life events, hopelessness, and coping strategies among impulsive suicide attempters.

    Science.gov (United States)

    Kattimani, Shivanand; Sarkar, Siddharth; Rajkumar, Ravi Philip; Menon, Vikas

    2015-01-01

    Suicides are among the most important causes of death in the economically productive population. Characteristics of impulsive and nonimpulsive suicide attempters may differ which would have a bearing on planning preventive measures. This study aimed to characterize the clinical and psychological profile of impulsive and nonimpulsive suicide attempters. This retrospective comprehensive chart-based study was conducted at a tertiary care hospital in South India. The study utilized records of patients over a period of 3 years. An attempt was considered impulsive if the time between suicidal idea and the attempt was hopelessness was evaluated using Beck Hopelessness Scale (BHS) and coping was measured using Coping Strategies Inventory Short Form. Impulsive and nonimpulsive suicide attempters were compared using appropriate inferential statistical tests. Of 316 patients, 151 were classified as having an impulsive suicidal attempt (47.8% of the sample). The impulsive and nonimpulsive suicide attempters did not differ on demographic characteristics. Use of natural plant products was more common in impulsive attempters (27.2% vs. 12.7%), while physical methods like hanging was less common (0.7% vs. 7.3%). Those with an impulsive attempt were more likely to have a recent contact with a health professional (24.5% vs. 4.5%). Impulsive suicide attempters had higher scores on BHS (Mann-Whitney U = 7680.5, P suicide attempters differ from nonimpulsive suicide attempters in clinical features like methods of attempt, presence of hopelessness, and stressors.

  11. Major stressful life events in relation to prevalence of undetected type 2 diabetes : the Hoorn Study

    NARCIS (Netherlands)

    Mooy, J M; de Vries, H; Grootenhuis, P A; Bouter, L M; Heine, R J

    OBJECTIVE: To test whether chronic psychological stress is positively associated 1) with the prevalence of type 2 diabetes; 2) with visceral adiposity; and to test whether 3) the relationship between stress and diabetes is mainly mediated by visceral adiposity RESEARCH DESIGN AND METHODS: In a

  12. Coping flexibility and psychological adjustment to stressful life changes: a meta-analytic review.

    Science.gov (United States)

    Cheng, Cecilia; Lau, Hi-Po Bobo; Chan, Man-Pui Sally

    2014-11-01

    Compared with the large body of literature on coping, coping flexibility has received relatively scant research attention, although more such studies have begun to emerge recently. Researchers have conceptualized coping flexibility in diverse ways: as a broad coping repertoire, a well-balanced coping profile, cross-situational variability in strategy deployment, a good strategy-situation fit, or the perceived ability to cope with environmental changes. This meta-analysis is the first to provide a summary estimate of the overall effect size and investigate cross-study sources of variation in the beneficial role of coping flexibility. The analysis covers all available studies conducted between 1978 and 2013 that empirically tested the relationship between coping flexibility and psychological adjustment. The results of a random-effects model revealed a small to moderate overall mean effect size (r = .23, 95% CI [.19, .28], 80% CRI [-.02, .49], k = 329, N = 58,946). More important, the magnitude of the positive link between coping flexibility and psychological adjustment varied with the conceptualization of such flexibility. Studies adopting the perceived ability or strategy-situation fit conceptualization yielded moderate effect sizes, whereas those adopting the broad repertoire, balanced profile, or cross-situational variability conceptualization yielded small effect sizes. In addition, the positive link between coping flexibility and psychological adjustment was stronger in samples from countries lower (vs. higher) in individualism and samples with higher (vs. lower) average ages. Individualism and age explained 10% and 13% of the variance, respectively. We discuss the conceptual problems and implications and propose a synthesized conceptualization of coping flexibility. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

  13. Humor Use Moderates the Relation of Stressful Life Events With Psychological Distress.

    Science.gov (United States)

    Fritz, Heidi L; Russek, Leslie N; Dillon, Melissa M

    2017-06-01

    Three studies examined humor and adjustment to stressful events. In Study 1, patients with fibromyalgia syndrome ( N = 22) reported on mental and physical adjustment, social interaction, and reappraisal of their illness. Dispositional humor was associated with reduced distress and fewer physical symptoms. Study 2 ( N = 109) examined undergraduates' reports of stressful events. Dispositional, self-enhancing, affiliative, and self-defeating humor showed direct effects on distress, which were mediated by social interaction and reappraisal. Moreover, dispositional and aggressive humor showed stress-buffering effects. Study 3 ( N = 105) examined undergraduates' adjustment to the September 11, 2001, attacks at 1 and 3 months postattack. At T1, affiliative humor showed a stress-buffering effect on distress. Social interaction mediated the relation of self-enhancing humor with reduced T1 distress, and mediated relations of aggressive and self-defeating humor with greater distress. Relations of T1 dispositional and self-defeating humor to changes in T2 distress were mediated by reappraisal.

  14. Towards Kilo-Hertz 6-DoF Visual Tracking Using an Egocentric Cluster of Rolling Shutter Cameras.

    Science.gov (United States)

    Bapat, Akash; Dunn, Enrique; Frahm, Jan-Michael

    2016-11-01

    To maintain a reliable registration of the virtual world with the real world, augmented reality (AR) applications require highly accurate, low-latency tracking of the device. In this paper, we propose a novel method for performing this fast 6-DOF head pose tracking using a cluster of rolling shutter cameras. The key idea is that a rolling shutter camera works by capturing the rows of an image in rapid succession, essentially acting as a high-frequency 1D image sensor. By integrating multiple rolling shutter cameras on the AR device, our tracker is able to perform 6-DOF markerless tracking in a static indoor environment with minimal latency. Compared to state-of-the-art tracking systems, this tracking approach performs at significantly higher frequency, and it works in generalized environments. To demonstrate the feasibility of our system, we present thorough evaluations on synthetically generated data with tracking frequencies reaching 56.7 kHz. We further validate the method's accuracy on real-world images collected from a prototype of our tracking system against ground truth data using standard commodity GoPro cameras capturing at 120 Hz frame rate.

  15. 2 Gigo.hertz Light Route Ro.die Relo.y Link between Asmo.ro. o.nd ...

    African Journals Online (AJOL)

    - blem of calculating the signal to noise ratio of a path is given below. The example quoted is the. 60 km path between Asmara and Massawa 2GHz system. In the calculation the following equipment and circuit parameters have been applied:.

  16. Analytical design of a parasitic-loading digital speed controller for a 400-hertz turbine driven alternator

    Science.gov (United States)

    Ingle, B. D.; Ryan, J. P.

    1972-01-01

    A design for a solid-state parasitic speed controller using digital logic was analyzed. Parasitic speed controllers are used in space power electrical generating systems to control the speed of turbine-driven alternators within specified limits. The analysis included the performance characteristics of the speed controller and the generation of timing functions. The speed controller using digital logic applies step loads to the alternator. The step loads conduct for a full half wave starting at either zero or 180 electrical degrees.

  17. Propagation of nuclear burning fronts on accreting neutron stars: X-ray bursts and sub-hertz noise

    Science.gov (United States)

    Bildsten, Lars

    1995-01-01

    We identify a new regime of time dependent helium burning for high accretion rate neutron stars and suggest that this burning is the origin of the low-level luminosity variations (on timescales of 10-10(exp 4) s, designated the 'very low-frequency noise'(VLFN) by van der Klis and collaborators) always detected in the brightest accreting X-ray sources. Only two nuclear burning regimes were previously recognized. At accretion rates in excess of the Eddington limit (dot-M approximately greater than (1-3) x 10(exp -8) solar mass/yr), the accreted matter fuses steadily. At very low dot-M, the star's entire surface is rapidly (approximately less than 10 s) burned by a fast propagating convective burning front at regular intervals, giving quasi-periodic Type I X-ray bursts. We show that for the observationally interesting range of 5 x 10(exp -10) solar mass/yr approximately less than dot-M approximately less than 10(exp -8) solar mass/yr, parts of the stellar surface burn slowly. At these accretion rates, a local thermonuclear instability starts a fire which propagates horizontally at v approximately 300 cm/s. The fire propagates around the flammable surface in roughly the same time it takes to accrete enough fuel for the next instability (approximately 10(exp 3)-10(exp 4), so that only a few fires are burning at once, giving rise to large luminosity flares. Nuclear burning is always time dependent for sub-Eddington local accretion rates: a local patch undergoes a recurrent cycle, accumulation fuel for hours until it becomes thermally unstable or is 'ignited' by a nearby burning region. The global pattern of burning and the resulting luminosity are thus very dependent on how fast nuclear fires spread around the star. The nuclear burning luminosity is not uniform over the stellar surface and so may provide a handle on measuring, or constraining, the spin periods of these neutron stars.

  18. Response of Global Navigation Satellite System receivers to known shaking between 0.2 and 20 Hertz

    Science.gov (United States)

    Langbein, John; Evans, John R.; Blume, Fredrick; Johanson, Ingrid

    2014-01-01

    Over the past decade, several technological advances have allowed Global Navigation Satellite Systems (GNSS) receivers to have the capability to record displacements at high frequencies, with sampling rates approaching 100 samples per second (sps). In addition, communication and computer hardware and software have allowed various institutions, including the U.S. Geological Survey (USGS), to retrieve, process, and display position changes recorded by a network of GNSS sites with small, less than 1-s delays between the time that the GNSS receiver records signals from a constellation of satellites and the time that the position is estimated (a method known as “real-time”). These improvements in hardware and software have allowed the USGS to process GNSS (or a subset of the GNSS, the Global Positioning System, GPS) data in real-time at 1 sps with the goal of determining displacements from earthquakes and volcanoes in real-time. However, the current set of GNSS equipment can record at rates of 100 sps, which allows the possibility of using this equipment to record earthquake displacements over the full range of frequencies that typically are recorded by acceleration and velocity transducers. The advantage of using GNSS to record earthquakes is that the displacement, rather than acceleration or velocity, is recorded, and for large earthquakes, the GNSS sensor stays on scale and will not distort the observations due to clipping of the signal at its highest amplitude. The direct observation of displacement is advantageous in estimating the size and spatial extent of the earthquake rupture. Otherwise, when using velocity or acceleration sensors, the displacements are determined by numerical integration of the observations, which can introduce significant uncertainty in the estimated displacements. However, GNSS technology can, at best, resolve displacements of a few millimeters, and for most earthquakes, their displacements are less than 1 mm. Consequently, to be useful, GNSS data are only relevant for the large earthquakes with magnitudes (M) exceeding M5.5 at best.

  19. Circuit performance of a parasitic-loading digital speed controller for a 400-hertz turbine-driven alternator

    Science.gov (United States)

    Ryan, J. P.; Ingle, B. D.

    1972-01-01

    Parasitic speed controllers are used in space power electrical generating systems to maintain the speed of the turbine-driven alternators within specified limits. Selected subcircuits for a solid state parasitic-loading speed controller were assembled and tested. The test results as obtained to date consist of the performance evaluation of the frequency reference and the period counter subcircuits. These circuits performed as expected.

  20. A method of selecting grid size to account for Hertz deformation in finite element analysis of spur gears

    Science.gov (United States)

    Coy, J. J.; Chao, C. H. C.

    1981-01-01

    A method of selecting grid size for the finite element analysis of gear tooth deflection is presented. The method is based on a finite element study of two cylinders in line contact, where the criterion for establishing element size was that there be agreement with the classical Hertzian solution for deflection. The results are applied to calculate deflection for the gear specimen used in the NASA spur gear test rig. Comparisons are made between the present results and the results of two other methods of calculation. The results have application in design of gear tooth profile modifications to reduce noise and dynamic loads.