Double universe and the arrow of time

Energy Technology Data Exchange (ETDEWEB)

Alfinito, Eleonora [Dipartimento di Ingegneria dell' Innovazione, Universitta di Lecce, 73100 Lecce and CNISM-Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia. Universita di Lecce (Italy); Vitiello, Giuseppe [Dipartimento di Fisica, Universita di Salerno, and INFN Gruppo Collegato di Salerno, 84100 Salerno (Italy)

2007-05-15

The canonical quantum field theory formalism for the expanding geometry universe leads to the 'Double Universe' scenario envisaged by quantum loop gravity. Thermal properties of inflating universe and the classicality of the time-evolution trajectories in the space of the representations of the canonical commutation relations are also discussed.

Quantum universe on extremely small space-time scales

International Nuclear Information System (INIS)

Kuzmichev, V.E.; Kuzmichev, V.V.

2010-01-01

The semiclassical approach to the quantum geometrodynamical model is used for the description of the properties of the Universe on extremely small space-time scales. Under this approach, the matter in the Universe has two components of the quantum nature which behave as antigravitating fluids. The first component does not vanish in the limit h → 0 and can be associated with dark energy. The second component is described by an extremely rigid equation of state and goes to zero after the transition to large spacetime scales. On small space-time scales, this quantum correction turns out to be significant. It determines the geometry of the Universe near the initial cosmological singularity point. This geometry is conformal to a unit four-sphere embedded in a five-dimensional Euclidean flat space. During the consequent expansion of the Universe, when reaching the post-Planck era, the geometry of the Universe changes into that conformal to a unit four-hyperboloid in a five-dimensional Lorentzsignatured flat space. This agrees with the hypothesis about the possible change of geometry after the origin of the expanding Universe from the region near the initial singularity point. The origin of the Universe can be interpreted as a quantum transition of the system from a region in the phase space forbidden for the classical motion, but where a trajectory in imaginary time exists, into a region, where the equations of motion have the solution which describes the evolution of the Universe in real time. Near the boundary between two regions, from the side of real time, the Universe undergoes almost an exponential expansion which passes smoothly into the expansion under the action of radiation dominating over matter which is described by the standard cosmological model.

Biological variation in tPA-induced plasma clot lysis time.

Science.gov (United States)

Talens, Simone; Malfliet, Joyce J M C; Rudež, Goran; Spronk, Henri M H; Janssen, Nicole A H; Meijer, Piet; Kluft, Cornelis; de Maat, Moniek P M; Rijken, Dingeman C

2012-10-01

Hypofibrinolysis is a risk factor for venous and arterial thrombosis, and can be assessed by using a turbidimetric tPA-induced clot lysis time (CLT) assay. Biological variation in clot lysis time may affect the interpretation and usefulness of CLT as a risk factor for thrombosis. Sufficient information about assay variation and biological variation in CLT is not yet available. Thus, this study aimed to determine the analytical, within-subject and between-subject variation in CLT. We collected blood samples from 40 healthy individuals throughout a period of one year (average 11.8 visits) and determined the CLT of each plasma sample in duplicate. The mean (± SD) CLT was 83.8 (± 11.1) minutes. The coefficients of variation for total variation, analytical variation, within-subject variation and between-subject variation were 13.4%, 2.6%, 8.2% and 10.2%, respectively. One measurement can estimate the CLT that does not deviate more than 20% from its true value. The contribution of analytical variation to the within-subject variation was 5.0%, the index of individuality was 0.84 and the reference change value was 23.8%. The CLT was longer in the morning compared to the afternoon and was slightly longer in older individuals (> 40 years) compared to younger (≤40 years) individuals. There was no seasonal variation in CLT and no association with air pollution. CLT correlated weakly with fibrinogen, C-reactive protein, prothrombin time and thrombin generation. This study provides insight into the biological variation of CLT, which can be used in future studies testing CLT as a potential risk factor for thrombosis.

Time to Tenure in Spanish Universities: An Event History Analysis

Science.gov (United States)

Sanz-Menéndez, Luis; Cruz-Castro, Laura; Alva, Kenedy

2013-01-01

Understanding how institutional incentives and mechanisms for assigning recognition shape access to a permanent job is important. This study, based on data from questionnaire survey responses and publications of 1,257 university science, biomedical and engineering faculty in Spain, attempts to understand the timing of getting a permanent position and the relevant factors that account for this transition, in the context of dilemmas between mobility and permanence faced by organizations. Using event history analysis, the paper looks at the time to promotion and the effects of some relevant covariates associated to academic performance, social embeddedness and mobility. We find that research productivity contributes to career acceleration, but that other variables are also significantly associated to a faster transition. Factors associated to the social elements of academic life also play a role in reducing the time from PhD graduation to tenure. However, mobility significantly increases the duration of the non-tenure stage. In contrast with previous findings, the role of sex is minor. The variations in the length of time to promotion across different scientific domains is confirmed, with faster career advancement for those in the Engineering and Technological Sciences compared with academics in the Biological and Biomedical Sciences. Results show clear effects of seniority, and rewards to loyalty, in addition to some measurements of performance and quality of the university granting the PhD, as key elements speeding up career advancement. Findings suggest the existence of a system based on granting early permanent jobs to those that combine social embeddedness and team integration with some good credentials regarding past and potential future performance, rather than high levels of mobility. PMID:24116199

Time to tenure in Spanish universities: an event history analysis.

Science.gov (United States)

Sanz-Menéndez, Luis; Cruz-Castro, Laura; Alva, Kenedy

2013-01-01

Understanding how institutional incentives and mechanisms for assigning recognition shape access to a permanent job is important. This study, based on data from questionnaire survey responses and publications of 1,257 university science, biomedical and engineering faculty in Spain, attempts to understand the timing of getting a permanent position and the relevant factors that account for this transition, in the context of dilemmas between mobility and permanence faced by organizations. Using event history analysis, the paper looks at the time to promotion and the effects of some relevant covariates associated to academic performance, social embeddedness and mobility. We find that research productivity contributes to career acceleration, but that other variables are also significantly associated to a faster transition. Factors associated to the social elements of academic life also play a role in reducing the time from PhD graduation to tenure. However, mobility significantly increases the duration of the non-tenure stage. In contrast with previous findings, the role of sex is minor. The variations in the length of time to promotion across different scientific domains is confirmed, with faster career advancement for those in the Engineering and Technological Sciences compared with academics in the Biological and Biomedical Sciences. Results show clear effects of seniority, and rewards to loyalty, in addition to some measurements of performance and quality of the university granting the PhD, as key elements speeding up career advancement. Findings suggest the existence of a system based on granting early permanent jobs to those that combine social embeddedness and team integration with some good credentials regarding past and potential future performance, rather than high levels of mobility.

Time to tenure in Spanish universities: an event history analysis.

Directory of Open Access Journals (Sweden)

Luis Sanz-Menéndez

Full Text Available Understanding how institutional incentives and mechanisms for assigning recognition shape access to a permanent job is important. This study, based on data from questionnaire survey responses and publications of 1,257 university science, biomedical and engineering faculty in Spain, attempts to understand the timing of getting a permanent position and the relevant factors that account for this transition, in the context of dilemmas between mobility and permanence faced by organizations. Using event history analysis, the paper looks at the time to promotion and the effects of some relevant covariates associated to academic performance, social embeddedness and mobility. We find that research productivity contributes to career acceleration, but that other variables are also significantly associated to a faster transition. Factors associated to the social elements of academic life also play a role in reducing the time from PhD graduation to tenure. However, mobility significantly increases the duration of the non-tenure stage. In contrast with previous findings, the role of sex is minor. The variations in the length of time to promotion across different scientific domains is confirmed, with faster career advancement for those in the Engineering and Technological Sciences compared with academics in the Biological and Biomedical Sciences. Results show clear effects of seniority, and rewards to loyalty, in addition to some measurements of performance and quality of the university granting the PhD, as key elements speeding up career advancement. Findings suggest the existence of a system based on granting early permanent jobs to those that combine social embeddedness and team integration with some good credentials regarding past and potential future performance, rather than high levels of mobility.

Time-symmetric universe model and its observational implication

Energy Technology Data Exchange (ETDEWEB)

Futamase, T.; Matsuda, T.

1987-08-01

A time-symmetric closed-universe model is discussed in terms of the radiation arrow of time. The time symmetry requires the occurrence of advanced waves in the recontracting phase of the Universe. We consider the observational consequences of such advanced waves, and it is shown that a test observer in the expanding phase can observe a time-reversed image of a source of radiation in the future recontracting phase.

Universals and cultural variations in 22 emotional expressions across five cultures.

Science.gov (United States)

Cordaro, Daniel T; Sun, Rui; Keltner, Dacher; Kamble, Shanmukh; Huddar, Niranjan; McNeil, Galen

2018-02-01

We collected and Facial Action Coding System (FACS) coded over 2,600 free-response facial and body displays of 22 emotions in China, India, Japan, Korea, and the United States to test 5 hypotheses concerning universals and cultural variants in emotional expression. New techniques enabled us to identify cross-cultural core patterns of expressive behaviors for each of the 22 emotions. We also documented systematic cultural variations of expressive behaviors within each culture that were shaped by the cultural resemblance in values, and identified a gradient of universality for the 22 emotions. Our discussion focused on the science of new expressions and how the evidence from this investigation identifies the extent to which emotional displays vary across cultures. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

'Universal' Distribution of Interearthquake Times Explained

International Nuclear Information System (INIS)

Saichev, A.; Sornette, D.

2006-01-01

We propose a simple theory for the 'universal' scaling law previously reported for the distributions of waiting times between earthquakes. It is based on a largely used benchmark model of seismicity, which just assumes no difference in the physics of foreshocks, mainshocks, and aftershocks. Our theoretical calculations provide good fits to the data and show that universality is only approximate. We conclude that the distributions of interevent times do not reveal more information than what is already known from the Gutenberg-Richter and the Omori power laws. Our results reinforce the view that triggering earthquakes by other earthquakes is a key physical mechanism to understand seismicity

Stochastic time scale for the Universe

International Nuclear Information System (INIS)

Szydlowski, M.; Golda, Z.

1986-01-01

An intrinsic time scale is naturally defined within stochastic gradient dynamical systems. It should be interpreted as a ''relaxation time'' to a local potential minimum after the system has been randomly perturbed. It is shown that for a flat Friedman-like cosmological model this time scale is of order of the age of the Universe. 7 refs. (author)

Timing Variations in Two Balkan Percussion Performances

Directory of Open Access Journals (Sweden)

Daniel Goldberg

2016-01-01

Full Text Available Many songs and dance pieces from the Balkan Peninsula employ aksak meter, in which two categorically different durations, long and short, coexist in the sequence of beats that performers emphasize and listeners move to. This paper analyzes the durations of aksak beats and measures in two recorded percussion performances that use a particular aksak beat sequence, long-short-short. The results suggest that the timing of beats varies in conjunction with factors including melodic grouping and interaction among members of a performing ensemble and audience. Timing variation linked to melodic groups occurs on a solo recording of a Macedonian Romani folk song. The performer, Muzafer Bizlim, taps an ostinato while singing, and the timing of his taps seems to mark some local and large-scale group boundaries. Melodic organization also seems relevant to the timing of beats and measures on a recording of Bulgarian percussionist Mitko Popov playing the tŭpan, a double-headed bass drum, in a small folk music ensemble. In Popov’s performance, however, timing differences might be related to characteristics of the ensemble dynamic, such as the coordination of multiple musical participants. These interpretations generate possibilities for future study of timing variations in relation to rhythm and meter.

Time variation of fundamental couplings and dynamical dark energy

International Nuclear Information System (INIS)

Dent, Thomas; Stern, Steffen; Wetterich, Christof

2009-01-01

Scalar field dynamics may give rise to a nonzero cosmological variation of fundamental constants. Within different scenarios based on the unification of gauge couplings, the various claimed observations and bounds may be combined in order to trace or restrict the time history of the couplings and masses. If the scalar field is responsible for a dynamical dark energy or quintessence, cosmological information becomes available for its time evolution. Combining this information with the time variation of couplings, one can determine the interaction strength between the scalar and atoms, which may be observed by tests of the Weak Equivalence Principle. We compute bounds on the present rate of coupling variation from experiments testing the differential accelerations for bodies with equal mass and different composition and compare the sensitivity of various methods. In particular, we discuss two specific models of scalar evolution: crossover quintessence and growing neutrino models

Universal data compression and repetition times

NARCIS (Netherlands)

Willems, Frans M J

1989-01-01

A new universal data compression algorithm is described. This algorithm encodes L source symbols at a time. For the class of binary stationary sources, its rate does not exceed [formula omitted] [formula omitted] bits per source symbol. In our analysis, a property of repetition times turns out to be

Modelling the quiet-time geomagnetic daily variations using observatory data

OpenAIRE

Hamilton, Brian; Macmillan, Susan

2008-01-01

We present on-going work towards building a global model of the quiet-time geomagnetic daily variation using bservatory data. We select hourly mean data during June 2006 (solar minimum). We fit Fourier series in time, with a fundamental period of 24 hours, to the data at each observatory. We then use global spherical harmonic expansions to separate the daily variation signal, as characterised by the Fourier coefficients in time, into external and induced internal contributions. The mode...

A time-symmetric Universe model and its observational implication

International Nuclear Information System (INIS)

Futamase, T.; Matsuda, T.

1987-01-01

A time-symmetric closed-universe model is discussed in terms of the radiation arrow of time. The time symmetry requires the occurrence of advanced waves in the recontracting phase of the Universe. The observational consequences of such advanced waves are considered, and it is shown that a test observer in the expanding phase can observe a time-reversed image of a source of radiation in the future recontracting phase

Time-Dependent Variations of Accretion Disk

Directory of Open Access Journals (Sweden)

Hye-Weon Na

1987-06-01

Full Text Available In dward nova we assume the primary star as a white dwarf and the secondary as the late type star which filled Roche lobe. Mass flow from the secondary star leads to the formation of thin accretion disk around the white dwarf. We use the α parameter as viscosity to maintain the disk form and propose that the outburst in dwarf nova cause the steep increase of source term. With these assumptions we solve the basic equations of stellar structure using Newton-Raphson method. We show the physical parameters like temperature, density, pressure, opacity, surface density, height and flux to the radius of disk. Changing the value of α, we compare several parameters when mass flow rate is constant with those of when luminosity of disk is brightest. At the same time, we obtain time-dependent variations of luminosity and mass of disk. We propose the suitable range of α is 0.15-0.18 to the difference of luminosity. We compare several parameters of disk with those of the normal late type stars which have the same molecular weight of disk is lower. Maybe the outburst in dwarf nova is due to the variation of the α value instead of increment of mass flow from the secondary star.

Beyond the dynamical universe unifying block universe physics and time as experienced

CERN Document Server

Silberstein, Michael; McDevitt, Timothy

2018-01-01

Theoretical physics and foundations of physics have not made much progress in the last few decades. Whether we are talking about unifying general relativity and quantum field theory (quantum gravity), explaining so-called dark energy and dark matter (cosmology), or the interpretation and implications of quantum mechanics and relativity, there is no consensus in sight. In addition, both enterprises are deeply puzzled about various facets of time including above all, time as experienced. The authors argue that, across the board, this impasse is the result of the "dynamical universe paradigm," the idea that reality is fundamentally made up of physical entities that evolve in time from some initial state according to dynamical laws. Thus, in the dynamical universe, the initial conditions plus the dynamical laws explain everything else going exclusively forward in time. In cosmology, for example, the initial conditions reside in the Big Bang and the dynamical law is supplied by general relativity. Accordingly, th...

Deterministic Chaos in Radon Time Variation

International Nuclear Information System (INIS)

Planinic, J.; Vukovic, B.; Radolic, V.; Faj, Z.; Stanic, D.

2003-01-01

Radon concentrations were continuously measured outdoors, in living room and basement in 10-minute intervals for a month. The radon time series were analyzed by comparing algorithms to extract phase-space dynamical information. The application of fractal methods enabled to explore the chaotic nature of radon in the atmosphere. The computed fractal dimensions, such as Hurst exponent (H) from the rescaled range analysis, Lyapunov exponent (λ ) and attractor dimension, provided estimates of the degree of chaotic behavior. The obtained low values of the Hurst exponent (0< H<0.5) indicated anti-persistent behavior (non random changes) of the time series, but the positive values of the λ pointed out the grate sensitivity on initial conditions and appearing deterministic chaos by radon time variations. The calculated fractal dimensions of attractors indicated more influencing (meteorological) parameters on radon in the atmosphere. (author)

Radon time variations and deterministic chaos

Energy Technology Data Exchange (ETDEWEB)

Planinic, J. E-mail: planinic@pedos.hr; Vukovic, B.; Radolic, V

2004-07-01

Radon concentrations were continuously measured outdoors, in the living room and in the basement at 10 min intervals for a month. Radon time series were analyzed by comparing algorithms to extract phase space dynamical information. The application of fractal methods enabled exploration of the chaotic nature of radon in atmosphere. The computed fractal dimensions, such as the Hurst exponent (H) from the rescaled range analysis, Lyapunov exponent ({lambda}) and attractor dimension, provided estimates of the degree of chaotic behavior. The obtained low values of the Hurst exponent (0time series, but the positive values of {lambda} pointed out the grate sensitivity on initial conditions and the deterministic chaos that appeared due to radon time variations. The calculated fractal dimensions of attractors indicated more influencing (meteorological) parameters on radon in the atmosphere.

Radon time variations and deterministic chaos

International Nuclear Information System (INIS)

Planinic, J.; Vukovic, B.; Radolic, V.

2004-01-01

Radon concentrations were continuously measured outdoors, in the living room and in the basement at 10 min intervals for a month. Radon time series were analyzed by comparing algorithms to extract phase space dynamical information. The application of fractal methods enabled exploration of the chaotic nature of radon in atmosphere. The computed fractal dimensions, such as the Hurst exponent (H) from the rescaled range analysis, Lyapunov exponent (λ) and attractor dimension, provided estimates of the degree of chaotic behavior. The obtained low values of the Hurst exponent (0< H<0.5) indicated anti-persistent behavior (non-random changes) of the time series, but the positive values of λ pointed out the grate sensitivity on initial conditions and the deterministic chaos that appeared due to radon time variations. The calculated fractal dimensions of attractors indicated more influencing (meteorological) parameters on radon in the atmosphere

Population growth enhances the mean fixation time of neutral mutations and the persistence of neutral variation.

Science.gov (United States)

Waxman, D

2012-06-01

A fundamental result of population genetics states that a new mutation, at an unlinked neutral locus in a randomly mating diploid population, has a mean time of fixation of ∼4N(e) generations, where N(e) is the effective population size. This result is based on an assumption of fixed population size, which does not universally hold in natural populations. Here, we analyze such neutral fixations in populations of changing size within the framework of the diffusion approximation. General expressions are derived for the mean and variance of the fixation time in changing populations. Some explicit results are given for two cases: (i) the effective population size undergoes a sudden change, representing a sudden population expansion or a sudden bottleneck; (ii) the effective population changes linearly for a limited period of time and then remains constant. Additionally, a lower bound for the mean time of fixation is obtained for an effective population size that increases with time, and this is applied to exponentially growing populations. The results obtained in this work show, among other things, that for populations that increase in size, the mean time of fixation can be enhanced, sometimes substantially so, over 4N(e,0) generations, where N(e,0) is the effective population size at the time the mutation arises. Such an enhancement is associated with (i) an increased probability of neutral polymorphism in a population and (ii) an enhanced persistence of high-frequency neutral variation, which is the variation most likely to be observed.

A Time Allocation Study of University Faculty

Science.gov (United States)

Link, Albert N.; Swann, Christopher A.; Bozeman, Barry

2008-01-01

Many previous time allocation studies treat work as a single activity and examine trade-offs between work and other activities. This paper investigates the at-work allocation of time among teaching, research, grant writing and service by science and engineering faculty at top US research universities. We focus on the relationship between tenure…

Variation in Part-Time Work among Pediatric Subspecialties.

Science.gov (United States)

Freed, Gary L; Boyer, Debra M; Van, Kenton D; Macy, Michelle L; McCormick, Julie; Leslie, Laurel K

2018-04-01

To assess the part-time workforce and average hours worked per week among pediatric subspecialists in the 15 medical subspecialties certified by the American Board of Pediatrics. We examined data from pediatric subspecialists who enrolled in Maintenance of Certification with the American Board of Pediatrics from 2009 to 2015. Data were collected via an online survey. Providers indicated whether they worked full time or part time and estimated the average number of hours worked per week in clinical, research, education, and administrative tasks, excluding time on call. We calculated and compared the range of hours worked by those in full- and part-time positions overall, by demographic characteristics, and by subspecialty. Overall, 9.6% of subspecialists worked part time. There was significant variation in part-time employment rates between subspecialties, ranging from 3.8% among critical care pediatricians to 22.9% among developmental-behavioral pediatricians. Women, American medical graduates, and physicians older than 70 years of age reported higher rates of part-time employment than men, international medical graduates, and younger physicians. There was marked variation in the number of hours worked across subspecialties. Most, but not all, full-time subspecialists reported working at least 40 hours per week. More than one-half of physicians working part time in hematology and oncology, pulmonology, and transplant hepatology reported working at least 40 hours per week. There are unique patterns of part-time employment and hours worked per week among pediatric medical subspecialists that make simple head counts inadequate to determine the effective workforce. Our findings are limited to the 15 American Board of Pediatrics-certified medical subspecialties. Copyright © 2017 Elsevier Inc. All rights reserved.

Outpatient waiting time in Jos University Teaching Hospital ...

African Journals Online (AJOL)

Problem Long waiting time for services has been identified as a reason people avoid presenting to for care in African countries. Design Examination of causes for long outpatient waiting time and the effect of measures to reduce waiting time. Setting Outpatient department of the Jos University Teaching Hospital.

The Pedagogical Variation Model (PVM) for Work-Based Training in Virtual Classrooms: Evaluation at Kuwait University

Science.gov (United States)

Rogers, Maria Susy; Aldhafeeri, Fayiz Mensher

2015-01-01

A collaborative research initiative was undertaken to evaluate the pedagogical variation model (PVM) for online learning and teaching at Kuwait University. Outcomes from sample populations of students--both postgraduates and undergraduates--from the Faculty of Education were analyzed for comparison. As predicted in the PVM, the findings indicate…

The Bright Universe Cosmology

International Nuclear Information System (INIS)

Surdin, M.

1980-01-01

It is shown that viewed from the 'outside', our universe is a black hole. Hence the 'inside' cosmology considered is termed as the Bright Universe Cosmology. The model proposed avoids the singularities of cosmologies of the Big Bang variety, it gives a good account of the redshifts, the cosmic background radiation, the number counts; it also gives a satisfactory explanation of the 'large numbers coincidence' and of the variation in time of fundamental constants. (Auth.)

Continuous radon measurements in schools: time variations and related parameters

International Nuclear Information System (INIS)

Giovani, C.; Cappelletto, C.; Garavaglia, M.; Pividore, S.; Villalta, R.

2004-01-01

Some results are reported of observations made within a four-year survey, during different seasons and in different conditions of school building use. Natural radon variations (day-night cycles, seasonal and temperature dependent variations etc..) and artificial ones (opening of windows, weekends and vacations, deployment of air conditioning or heating systems. etc.) were investigated as parameters affecting time dependent radon concentrations. (P.A.)

Training and evaluation of neural networks for multi-variate time series processing

DEFF Research Database (Denmark)

Fog, Torben L.; Larsen, Jan; Hansen, Lars Kai

1995-01-01

We study the training and generalization for multi-variate time series processing. It is suggested to used a quasi-maximum likelihood approach rather than the standard sum of squared errors, thus taking dependencies among the errors of the individual time series into account. This may lead...... to improved generalization performance. Further, we extend the optimal brain damage pruning technique to the multi-variate case. A key ingredient is an algebraic expression for the generalization ability of a multi-variate model. The variability of the suggested techniques are successfully demonstrated...

Pattern and Variation in the Timing of Aksak Meter: Commentary on Goldberg

OpenAIRE

Rainer Polak

2016-01-01

Daniel Goldberg (2015, this issue) explores relations between timing variations, grouping structure, and musical form in the percussive accompaniment of Balkan folk dance music. A chronometric re-analysis of one of the target article’s two audio samples finds a regular metric timing pattern to consistently underlie the variations Goldberg uncovered. Read together, the target article and this commentary demonstrate the complex interplay of a regular timing pattern with several levels of nuance...

Identifying significant temporal variation in time course microarray data without replicates

Directory of Open Access Journals (Sweden)

Porter Weston

2009-03-01

Full Text Available Abstract Background An important component of time course microarray studies is the identification of genes that demonstrate significant time-dependent variation in their expression levels. Until recently, available methods for performing such significance tests required replicates of individual time points. This paper describes a replicate-free method that was developed as part of a study of the estrous cycle in the rat mammary gland in which no replicate data was collected. Results A temporal test statistic is proposed that is based on the degree to which data are smoothed when fit by a spline function. An algorithm is presented that uses this test statistic together with a false discovery rate method to identify genes whose expression profiles exhibit significant temporal variation. The algorithm is tested on simulated data, and is compared with another recently published replicate-free method. The simulated data consists both of genes with known temporal dependencies, and genes from a null distribution. The proposed algorithm identifies a larger percentage of the time-dependent genes for a given false discovery rate. Use of the algorithm in a study of the estrous cycle in the rat mammary gland resulted in the identification of genes exhibiting distinct circadian variation. These results were confirmed in follow-up laboratory experiments. Conclusion The proposed algorithm provides a new approach for identifying expression profiles with significant temporal variation without relying on replicates. When compared with a recently published algorithm on simulated data, the proposed algorithm appears to identify a larger percentage of time-dependent genes for a given false discovery rate. The development of the algorithm was instrumental in revealing the presence of circadian variation in the virgin rat mammary gland during the estrous cycle.

Quantum field theory of the universe in the Kantowski-Sachs space-time

International Nuclear Information System (INIS)

Shen, Y.; Tan, Z.

1996-01-01

In this paper, the quantum field theory of the universe in the Kantowski-Sachs space-time is studied. An analogue of proceedings in quantum field theory is applied in curved space-time to the Kantowski-Sachs space-time, obtaining the wave function of the universe satisfied the Wheeler-DeWitt equation. Regarding the wave function as a universe field in the minisuperspace, the authors can not only overcome the difficulty of the probabilistic interpretation in quantum cosmology, but also come to the conclusion that there is multiple production of universes. The average number of the produced universes from nothing is calculated. The distribution of created universe is given. It is the Planckian distribution

Time-causal decomposition of geomagnetic time series into secular variation, solar quiet, and disturbance signals

Science.gov (United States)

Rigler, E. Joshua

2017-04-26

A theoretical basis and prototype numerical algorithm are provided that decompose regular time series of geomagnetic observations into three components: secular variation; solar quiet, and disturbance. Respectively, these three components correspond roughly to slow changes in the Earth’s internal magnetic field, periodic daily variations caused by quasi-stationary (with respect to the sun) electrical current systems in the Earth’s magnetosphere, and episodic perturbations to the geomagnetic baseline that are typically driven by fluctuations in a solar wind that interacts electromagnetically with the Earth’s magnetosphere. In contrast to similar algorithms applied to geomagnetic data in the past, this one addresses the issue of real time data acquisition directly by applying a time-causal, exponential smoother with “seasonal corrections” to the data as soon as they become available.

The Singular Universe and the Reality of Time

Science.gov (United States)

Mangabeira Unger, Roberto; Smolin, Lee

2015-01-01

Introduction; Part I. Roberto Mangabeira Unger: 1. The science of the one universe in time; 2. The context and consequences of the argument; 3. The singular existence of the universe; 4. The inclusive reality of time; 5. The mutability of the laws of nature; 6. The selective realism of mathematics; Part II. Lee Smolin: 1. Cosmology in crisis; 2. Principles for a cosmological theory; 3. The setting: the puzzles of contemporary cosmology; 4. Hypotheses for a new cosmology; 5. Mathematics; 6. Approaches to solving the metalaw dilemma; 7. Implications of temporal naturalism for philosophy of mind; 8. An agenda for science; 9. Concluding remarks; A note concerning disagreements between our views.

Feynman’s clock, a new variational principle, and parallel-in-time quantum dynamics

Science.gov (United States)

McClean, Jarrod R.; Parkhill, John A.; Aspuru-Guzik, Alán

2013-01-01

We introduce a discrete-time variational principle inspired by the quantum clock originally proposed by Feynman and use it to write down quantum evolution as a ground-state eigenvalue problem. The construction allows one to apply ground-state quantum many-body theory to quantum dynamics, extending the reach of many highly developed tools from this fertile research area. Moreover, this formalism naturally leads to an algorithm to parallelize quantum simulation over time. We draw an explicit connection between previously known time-dependent variational principles and the time-embedded variational principle presented. Sample calculations are presented, applying the idea to a hydrogen molecule and the spin degrees of freedom of a model inorganic compound, demonstrating the parallel speedup of our method as well as its flexibility in applying ground-state methodologies. Finally, we take advantage of the unique perspective of this variational principle to examine the error of basis approximations in quantum dynamics. PMID:24062428

Introducing sit-stand desks increases classroom standing time among university students

Directory of Open Access Journals (Sweden)

Matthew Jerome

2017-12-01

Full Text Available Excessive sedentary behavior has been associated with many negative health outcomes. While an understudied health topic, there is evidence that university students are excessively sedentary. Sit-stand desks have been shown to reduce sedentary time among pre-university students (ages 5–18years and sedentary workers but have not been tested in university classrooms. This study tested the effects of introducing sit-stand desks into a university classroom on student's classroom sitting and standing behaviors. Using a cross-over design, students received access to both traditional seated desks and sit-stand desks for six weeks. Data were collected between September and December, 2016. We recruited 304 healthy undergraduate university students enrolled in one of two small (25 seats classrooms at a large Midwestern university during the fall of 2016. Average minutes of standing/hour/student, average percent class time spent standing, and the number of sit-stand transitions/student/hour were directly observed with video camera surveillance. Participants stood significantly more (p<0.001 when provided access to sit-stand desks (7.2min/h/student; 9.3% of class time spent standing compared to when they had access to seated desks (0.7min/h/student; 1.6% of class time spent standing but no differences were observed for the number of sit-stand transitions (p=0.47. Students reported high favorability for the sit-stand desks and improvements in several student engagement and affective outcomes while using the sit-stand desks. These findings support introducing sit-stand desks in university classrooms as an approach to reduce sedentary behaviors of university students. Keywords: Sedentary, University students, Sit-stand desk

Transit timing observations from Kepler. V. Transit timing variation candidates in the first sixteen months from polynomial models

DEFF Research Database (Denmark)

Ford, E.B.; Ragozzine, D.; Holman, M.J.

2012-01-01

Transit timing variations provide a powerful tool for confirming and characterizing transiting planets, as well as detecting non-transiting planets. We report the results of an updated transit timing variation (TTV) analysis for 1481 planet candidates based on transit times measured during...... that several of these planet candidates could be confirmed and perhaps characterized with more detailed TTV analyses using publicly available Kepler observations. For many others, Kepler has observed a long-term TTV trend, but an extended Kepler mission will be required to characterize the system via TTVs. We...

Professional Learning in Part-time University Study

DEFF Research Database (Denmark)

Rasmussen, Palle

2007-01-01

The theme of this article is adult students' learning in part-time studies at university level in Denmark. One issue discussed is the interplay of research and teaching in this kind of study programme. Examples are presented from the Master of Learning Processes study programme at Aalborg...

Reducing lumber thickness variation using real-time statistical process control

Science.gov (United States)

Thomas M. Young; Brian H. Bond; Jan Wiedenbeck

2002-01-01

A technology feasibility study for reducing lumber thickness variation was conducted from April 2001 until March 2002 at two sawmills located in the southern U.S. A real-time statistical process control (SPC) system was developed that featured Wonderware human machine interface technology (HMI) with distributed real-time control charts for all sawing centers and...

Own-wage labor supply elasticities: variation across time and estimation methods

Directory of Open Access Journals (Sweden)

Olivier Bargain

2016-10-01

Full Text Available Abstract There is a huge variation in the size of labor supply elasticities in the literature, which hampers policy analysis. While recent studies show that preference heterogeneity across countries explains little of this variation, we focus on two other important features: observation period and estimation method. We start with a thorough survey of existing evidence for both Western Europe and the USA, over a long period and from different empirical approaches. Then, our meta-analysis attempts to disentangle the role of time changes and estimation methods. We highlight the key role of time changes, documenting the incredible fall in labor supply elasticities since the 1980s not only for the USA but also in the EU. In contrast, we find no compelling evidence that the choice of estimation method explains variation in elasticity estimates. From our analysis, we derive important guidelines for policy simulations.

Time dependent variational method in quantum mechanics

International Nuclear Information System (INIS)

Torres del Castillo, G.F.

1987-01-01

Using the fact that the solutions to the time-dependent Schodinger equation can be obtained from a variational principle, by restricting the evolution of the state vector to some surface in the corresponding Hilbert space, approximations to the exact solutions can be obtained, which are determined by equations similar to Hamilton's equations. It is shown that, in order for the approximate evolution to be well defined on a given surface, the imaginary part of the inner product restricted to the surface must be non-singular. (author)

Seasonal variations of the high-latitude F region for

International Nuclear Information System (INIS)

Sojka, J.J.; Schunk, R.W.; Raitt, W.J.

1982-01-01

We combined a plasma convection model with an inosphere-atmospheric composition model in order to study the seasonal variations of the high-latitude F region for strong convection. Our numerical study produced time-dependent, three-dimensional, ion density distributions for the ions NO + , O 2 + , N 2 + , O + , N + , and He + . We covered the high-latitude ionosphere above 42 0 N magnetic latitude and at altitudes between 160 and 800 km for a time period of one complete day. From our study we found the following: (1) For strong convection, the high-altitude ionosphere exhibits a significant UT variation both during winter and summer. (2) In general, the electron density is lower in winter than in summer. However, at certain universal times the electron density in the dayside polar cap is larger in winter than in summer owing to the effect of the mid-latitude 'winter anomaly' in combination with strong antisunward convection. (3) In both summer and winter, the major region of low electron density is associated with the main or mid-latitudde trough. The trough is deeper and its local time extend is much greater in winter than in summer. (4) Typically, the electron density exhibits a much larger variation with altitude in winter than in summer. (5) The ion composition and molecular/atomic ion transition altitude are highly UT dependent in both summer and winter. (6) The ion composition also displays a significant seasonal variation. However, at a given location the seasonal variation can be opposite at different universal times. (7) High-speed convection cells should display a marked seasonal variation, with a much larger concentration of molecular ions near the F region peak in summer than in winter

Stability Analysis and Variational Integrator for Real-Time Formation Based on Potential Field

Directory of Open Access Journals (Sweden)

Shengqing Yang

2014-01-01

Full Text Available This paper investigates a framework of real-time formation of autonomous vehicles by using potential field and variational integrator. Real-time formation requires vehicles to have coordinated motion and efficient computation. Interactions described by potential field can meet the former requirement which results in a nonlinear system. Stability analysis of such nonlinear system is difficult. Our methodology of stability analysis is discussed in error dynamic system. Transformation of coordinates from inertial frame to body frame can help the stability analysis focus on the structure instead of particular coordinates. Then, the Jacobian of reduced system can be calculated. It can be proved that the formation is stable at the equilibrium point of error dynamic system with the effect of damping force. For consideration of calculation, variational integrator is introduced. It is equivalent to solving algebraic equations. Forced Euler-Lagrange equation in discrete expression is used to construct a forced variational integrator for vehicles in potential field and obstacle environment. By applying forced variational integrator on computation of vehicles' motion, real-time formation of vehicles in obstacle environment can be implemented. Algorithm based on forced variational integrator is designed for a leader-follower formation.

Introducing sit-stand desks increases classroom standing time among university students.

Science.gov (United States)

Jerome, Matthew; Janz, Kathleen F; Baquero, Barbara; Carr, Lucas J

2017-12-01

Excessive sedentary behavior has been associated with many negative health outcomes. While an understudied health topic, there is evidence that university students are excessively sedentary. Sit-stand desks have been shown to reduce sedentary time among pre-university students (ages 5-18 years) and sedentary workers but have not been tested in university classrooms. This study tested the effects of introducing sit-stand desks into a university classroom on student's classroom sitting and standing behaviors. Using a cross-over design, students received access to both traditional seated desks and sit-stand desks for six weeks. Data were collected between September and December, 2016. We recruited 304 healthy undergraduate university students enrolled in one of two small (25 seats) classrooms at a large Midwestern university during the fall of 2016. Average minutes of standing/hour/student, average percent class time spent standing, and the number of sit-stand transitions/student/hour were directly observed with video camera surveillance. Participants stood significantly more (p classrooms as an approach to reduce sedentary behaviors of university students.

Time Perspective, Life Satisfaction and Social Comparison Orientation in University Students

OpenAIRE

Nazmiye ÇİVİTCİ; Hülya ŞAHİN BALTACI

2018-01-01

The aim of this study was to examine the predictive power of time perspective for the life satisfaction and social comparison in university students. The participants (n= 441; 321 female and 120 male) are undergraduate students at a state university. The data of the study were collected through the Zimbardo Time Perspective Inventory, The Satisfaction with Life Scale and IOWA-Netherlands Social Comparison Orientation Measure. In order to determine the prediction power of the time ...

Universal behaviour in the stock market: Time dynamics of the electronic orderbook

Energy Technology Data Exchange (ETDEWEB)

Kızılersü, Ayşe, E-mail: ayse.kizilersu@adelaide.edu.au [Special Research Centre for the Subatomic Structure of Matter (CSSM), Department of Physics, School of Chemistry and Physics, Adelaide University, 5005 (Australia); Kreer, Markus [phi-t products & services, Karlsruher Strasse 88, 76139 Karlsruhe (Germany); Thomas, Anthony W. [CoEPP and CSSM, Department of Physics, Adelaide University, SA 5005 (Australia); Feindt, Michael [Blue Yonder GmbH, Ohiostraße 8, 756139 Karlsruhe (Germany)

2016-07-29

A consequence of the digital revolution is that share trading at the stock exchange takes place via electronic order books which are accessed by traders and investors via the internet. Our empirical findings of the London Stock Exchange demonstrate that once ultra-high frequency manipulation on time scales less than around ten milliseconds is excluded, all relevant changes in the order book happen with time differences that are randomly distributed and well described by a left-truncated Weibull distribution with universal shape parameter (independent of time and same for all stocks). The universal shape parameter corresponds to maximum entropy of the distribution. - Highlights: • After the ultra-high frequency manipulation is excluded, all the time differences in the EOB described by a left-truncated Weibull distribution. • The Weibull shape parameter is universal i.e. independent of time and same for all stocks and it is equal to Euler–Mascheroni constant. • The universal shape parameter corresponds to maximum entropy of the distribution.

Universal behaviour in the stock market: Time dynamics of the electronic orderbook

International Nuclear Information System (INIS)

Kızılersü, Ayşe; Kreer, Markus; Thomas, Anthony W.; Feindt, Michael

2016-01-01

A consequence of the digital revolution is that share trading at the stock exchange takes place via electronic order books which are accessed by traders and investors via the internet. Our empirical findings of the London Stock Exchange demonstrate that once ultra-high frequency manipulation on time scales less than around ten milliseconds is excluded, all relevant changes in the order book happen with time differences that are randomly distributed and well described by a left-truncated Weibull distribution with universal shape parameter (independent of time and same for all stocks). The universal shape parameter corresponds to maximum entropy of the distribution. - Highlights: • After the ultra-high frequency manipulation is excluded, all the time differences in the EOB described by a left-truncated Weibull distribution. • The Weibull shape parameter is universal i.e. independent of time and same for all stocks and it is equal to Euler–Mascheroni constant. • The universal shape parameter corresponds to maximum entropy of the distribution.

The evolving block universe and the meshing together of times.

Science.gov (United States)

Ellis, George F R

2014-10-01

It has been proposed that spacetime should be regarded as an evolving block universe, bounded to the future by the present time, which continually extends to the future. This future boundary is defined at each time by measuring proper time along Ricci eigenlines from the start of the universe. A key point, then, is that physical reality can be represented at many different scales: hence, the passage of time may be seen as different at different scales, with quantum gravity determining the evolution of spacetime itself at the Planck scale, but quantum field theory and classical physics determining the evolution of events within spacetime at larger scales. The fundamental issue then arises as to how the effective times at different scales mesh together, leading to the concepts of global and local times. © 2014 New York Academy of Sciences.

Acceleration of the universe, vacuum metamorphosis, and the large-time asymptotic form of the heat kernel

International Nuclear Information System (INIS)

Parker, Leonard; Vanzella, Daniel A.T.

2004-01-01

We investigate the possibility that the late acceleration observed in the rate of expansion of the Universe is due to vacuum quantum effects arising in curved spacetime. The theoretical basis of the vacuum cold dark matter (VCDM), or vacuum metamorphosis, cosmological model of Parker and Raval is reexamined and improved. We show, by means of a manifestly nonperturbative approach, how the infrared behavior of the propagator (related to the large-time asymptotic form of the heat kernel) of a free scalar field in curved spacetime leads to nonperturbative terms in the effective action similar to those appearing in the earlier version of the VCDM model. The asymptotic form that we adopt for the propagator or heat kernel at large proper time s is motivated by, and consistent with, particular cases where the heat kernel has been calculated exactly, namely in de Sitter spacetime, in the Einstein static universe, and in the linearly expanding spatially flat Friedmann-Robertson-Walker (FRW) universe. This large-s asymptotic form generalizes somewhat the one suggested by the Gaussian approximation and the R-summed form of the propagator that earlier served as a theoretical basis for the VCDM model. The vacuum expectation value for the energy-momentum tensor of the free scalar field, obtained through variation of the effective action, exhibits a resonance effect when the scalar curvature R of the spacetime reaches a particular value related to the mass of the field. Modeling our Universe by an FRW spacetime filled with classical matter and radiation, we show that the back reaction caused by this resonance drives the Universe through a transition to an accelerating expansion phase, very much in the same way as originally proposed by Parker and Raval. Our analysis includes higher derivatives that were neglected in the earlier analysis, and takes into account the possible runaway solutions that can follow from these higher-derivative terms. We find that the runaway solutions do

A COMPARISON ON THE TIME MANAGEMENT UNDERSTANDINGS OF UNIVERSITY ACADEMIC STAFF

Directory of Open Access Journals (Sweden)

Kubilay Çimen

2017-10-01

Full Text Available The aim of this study was to investigate time management understandings of university academic staff with their participation or not participation in the sports activities, gender and their work year. The sample of the study consisted of 93 university academic staff who Works at Dumlupinar University (37 women and 56 men. As data collection tool in addition to a questionary, which consists 10 items developed by the researchers, “Time Management Scale”, which was developed by Britton and Tesser (1991 and Turkish adaptation was done by Koçak and Alay (2002 was used. The obtained data were analyzed by using SPSS for windows. In addition to descriptive statistics, Mann Whitney U and Kruskal Wallis test were done in order to determine significant differences between time management understandings of the academic staff. As a result, although, there was no significant difference between participants’ time management understanding according to gender (p>.05 there were significant differences between participants’ time management understandings in the “time attitudes” subscale according to their work year and in “time management” and “time attitudes” subscales according to participation /or not participation in sport activities (p<.05.

Real-Time PCR for Universal Phytoplasma Detection and Quantification

DEFF Research Database (Denmark)

Christensen, Nynne Meyn; Nyskjold, Henriette; Nicolaisen, Mogens

2013-01-01

Currently, the most efficient detection and precise quantification of phytoplasmas is by real-time PCR. Compared to nested PCR, this method is less sensitive to contamination and is less work intensive. Therefore, a universal real-time PCR method will be valuable in screening programs and in other...

Pre-Big Bang, space-time structure, asymptotic Universe

Directory of Open Access Journals (Sweden)

Gonzalez-Mestres Luis

2014-04-01

Full Text Available Planck and other recent data in Cosmology and Particle Physics can open the way to controversial analyses concerning the early Universe and its possible ultimate origin. Alternatives to standard cosmology include pre-Big Bang approaches, new space-time geometries and new ultimate constituents of matter. Basic issues related to a possible new cosmology along these lines clearly deserve further exploration. The Planck collaboration reports an age of the Universe t close to 13.8 Gyr and a present ratio H between relative speeds and distances at cosmic scale around 67.3 km/s/Mpc. The product of these two measured quantities is then slightly below 1 (about 0.95, while it can be exactly 1 in the absence of matter and cosmological constant in patterns based on the spinorial space-time we have considered in previous papers. In this description of space-time we first suggested in 1996-97, the cosmic time t is given by the modulus of a SU(2 spinor and the Lundmark-Lemaître-Hubble (LLH expansion law turns out to be of purely geometric origin previous to any introduction of standard matter and relativity. Such a fundamental geometry, inspired by the role of half-integer spin in Particle Physics, may reflect an equilibrium between the dynamics of the ultimate constituents of matter and the deep structure of space and time. Taking into account the observed cosmic acceleration, the present situation suggests that the value of 1 can be a natural asymptotic limit for the product H t in the long-term evolution of our Universe up to possible small corrections. In the presence of a spinorial space-time geometry, no ad hoc combination of dark matter and dark energy would in any case be needed to get an acceptable value of H and an evolution of the Universe compatible with observation. The use of a spinorial space-time naturally leads to unconventional properties for the space curvature term in Friedmann-like equations. It therefore suggests a major modification of

Simple Model with Time-Varying Fine-Structure ``Constant''

Science.gov (United States)

Berman, M. S.

2009-10-01

Extending the original version written in colaboration with L.A. Trevisan, we study the generalisation of Dirac's LNH, so that time-variation of the fine-structure constant, due to varying electrical and magnetic permittivities is included along with other variations (cosmological and gravitational ``constants''), etc. We consider the present Universe, and also an inflationary scenario. Rotation of the Universe is a given possibility in this model.

Variation of explosive force at different times of day

Directory of Open Access Journals (Sweden)

R Pereira

2011-03-01

Full Text Available AIM: The purpose of this study was to compare the explosive force and electromyographic (EMG activity at three different times of the day. METHODS: Thirty healthy subjects took part in the study, and carried out two maximum isometric voluntary knee extensions to measure explosive force, through contractile impulse (CI and rate of force development (RFD, and myoelectric signals from quadriceps muscles in the following periods: 07:30-09:30, 13:30-15:30 and 19:30-21:30 (called morning, afternoon and night respectively, on three non-consecutive days. RESULTS: The body temperature was lower in the morning than in the afternoon and night periods. The explosive force, evaluated through contractile impulse (CI and rate of force development (RFD, was greater at night than in the morning, without differences in the myoelectric signal. CONCLUSION: The ability to produce explosive force varies throughout different times of the day without variation in muscular recruitment, indicating that peripheral and not neural mechanisms could be responsible for this variation.

Lyra’s cosmology of hybrid universe in Bianchi-V space-time

Science.gov (United States)

Yadav, Anil Kumar; Bhardwaj, Vinod Kumar

2018-06-01

In this paper we have searched for the existence of Lyra’s cosmology in a hybrid universe with minimal interaction between dark energy and normal matter using Bianchi-V space-time. To derive the exact solution, the average scale factor is taken as a={({t}n{e}kt)}\\frac{1{m}} which describes the hybrid nature of the scale factor and generates a model of the transitioning universe from the early deceleration phase to the present acceleration phase. The quintessence model makes the matter content of the derived universe remarkably able to satisfy the null, dominant and strong energy condition. It has been found that the time varying displacement β(t) co-relates with the nature of cosmological constant Λ(t). We also discuss some physical and geometrical features of the universe.

Inter-temporal variation in the travel time and travel cost parameters of transport models

OpenAIRE

Börjesson, Maria

2012-01-01

The parameters for travel time and travel cost are central in travel demand forecasting models. Since valuation of infrastructure investments requires prediction of travel demand for future evaluation years, inter-temporal variation of the travel time and travel cost parameters is a key issue in forecasting. Using two identical stated choice experiments conducted among Swedish drivers with an interval of 13 years, 1994 and 2007, this paper estimates the inter-temporal variation in travel time...

Time change and universality in turbulence

DEFF Research Database (Denmark)

Barndorff-Nielsen, Ole Eiler; Schmiegel, Jürgen

of the probability densities of turbulent velocity increments. Furthermore, the application of a time change in terms of the scale parameter δ of the normal inverse Gaussian distribution results in a collapse of the densities of velocity increments onto Reynolds number independent distributions. We discuss this kind...... experiment. Taylor Reynolds numbers range from Rλ = 80 for the wind tunnel experiment up to Rλ = 17000 for the atmospheric boundary layer experiment. Empirical findings strongly support the appropriateness of normal inverse Gaussian distributions for a parsimonious and universal description...

Fabrications, Time-Consuming Bureaucracy and Moral Dilemmas--Finnish University Employees' Experiences on the Governance of University Work

Science.gov (United States)

Jauhiainen, Arto; Jauhiainen, Annukka; Laiho, Anne; Lehto, Reeta

2015-01-01

This article explores how the university workers of two Finnish universities experienced the range of neoliberal policymaking and governance reforms implemented in the 2000s. These reforms include quality assurance, system of defined annual working hours, outcome-based salary system and work time allocation system. Our point of view regarding…

Time variable cosmological constants from the age of universe

International Nuclear Information System (INIS)

Xu Lixin; Lu Jianbo; Li Wenbo

2010-01-01

In this Letter, time variable cosmological constant, dubbed age cosmological constant, is investigated motivated by the fact: any cosmological length scale and time scale can introduce a cosmological constant or vacuum energy density into Einstein's theory. The age cosmological constant takes the form ρ Λ =3c 2 M P 2 /t Λ 2 , where t Λ is the age or conformal age of our universe. The effective equation of state (EoS) of age cosmological constant are w Λ eff =-1+2/3 (√(Ω Λ ))/c and w Λ eff =-1+2/3 (√(Ω Λ ))/c (1+z) when the age and conformal age of universe are taken as the role of cosmological time scales respectively. The EoS are the same as the so-called agegraphic dark energy models. However, the evolution histories are different from the agegraphic ones for their different evolution equations.

Universe before Planck time: A quantum gravity model

International Nuclear Information System (INIS)

Padmanabhan, T.

1983-01-01

A model for quantum gravity can be constructed by treating the conformal degree of freedom of spacetime as a quantum variable. An isotropic, homogeneous cosmological solution in this quantum gravity model is presented. The spacetime is nonsingular for all the three possible values of three-space curvature, and agrees with the classical solution for time scales larger than the Planck time scale. A possibility of quantum fluctuations creating the matter in the universe is suggested

Before time began the Big Bang and the emerging universe

CERN Document Server

Satz, Helmut

2017-01-01

What is the origin of the universe? What was there before the universe appeared? We are currently witnessing a second Copernican revolution: neither our Earth and Sun, nor our galaxy, nor even our universe, are the end of all things. Beyond our world, in an endless multiverse, are innumerable other universes, coming and going, like ours or different. Fourteen billion years ago, one of the many bubbles constantly appearing and vanishing in the multiverse exploded to form our universe. The energy liberated in the explosion provided the basis for all the matter our universe now contains. But how could this hot, primordial plasma eventually produce the complex structure of our present world? Does not order eventually always lead to disorder, to an increase of entropy? Modern cosmology is beginning to find out how it all came about and where it all might lead. Before Time Began tells that story.

Study of long-time variations of cosmic rays

International Nuclear Information System (INIS)

Dergachev, V.A.

1979-01-01

Discussed are some problems of the investigation into the cosmic rays intensity in the past via the contents of cosmogenic isotopes in the samples of known age, mainly measuring the activity of radiocarbon in the samples dated by the dendrochronological method. The necessity of production of the multicentury dendrochronological scales with absolute dating for decoding of the information contained in the annual rings during the large time scale is pointed out. The dendrochronologic studies supplemented by the radiocarbon dating would permit to study the variations in radiocarbon content and to determine the factors, which influence this content, during large time intervals. The different factors - the solar activity, the supernovae flares et cetera - influencing the radiocarbon concentration are considered

Part-Time Lecturers Teaching Part-Time Learners at University: A Transformation Issue

Science.gov (United States)

February, C.; Koetsier, J.; Walters, S.

2010-01-01

The relationship between the academic labour market and the global labour market provides an important context for this research. There appear to be growing numbers of part-time lecturers at universities worldwide, which is seen as an extension of casualisation of labour more generally. From a social justice perspective, it is therefore of concern…

Influence of Application Time and Etching Mode of Universal Adhesives on Enamel Adhesion.

Science.gov (United States)

Sai, Keiichi; Takamizawa, Toshiki; Imai, Arisa; Tsujimoto, Akimasa; Ishii, Ryo; Barkmeier, Wayne W; Latta, Mark A; Miyazaki, Masashi

2018-01-01

To investigate the influence of application time and etching mode of universal adhesives on enamel adhesion. Five universal adhesives, Adhese Universal, Bondmer Lightless, Clearfil Universal Bond Quick, G-Premio Bond, and Scotchbond Universal, were used. Bovine incisors were prepared and divided into four groups of ten teeth each. SBS, Ra, and SFE were determined after the following procedures: 1. self-etch mode with immediate air blowing after application (IA); 2. self-etch mode with prolonged application time (PA); 3. etch-and-rinse mode with IA; 4. etch-and-rinse mode with PA. After 24-h water storage, the bonded assemblies were subjected to shear bond strength (SBS) tests. For surface roughness (Ra) and surface free energy (SFE) measurements, the adhesives were simply applied to the enamel and rinsed with acetone and water before the measurements were carried out. Significantly higher SBS and Ra values were obtained with etch-and-rinse mode than with self-etch mode regardless of the application time or type of adhesive. Although most adhesives showed decreased SFE values with increased application time in self-etch mode, SFE values in etch-and-rinse mode were dependent on the adhesive type and application time. Etching mode, application time, and type of adhesive significantly influenced the SBS, Ra, and SFE values.

The quantum theory of time, the block universe, and human experience.

Science.gov (United States)

Vaccaro, Joan A

2018-07-13

Advances in our understanding of the physical universe have dramatically affected how we view ourselves. Right at the core of all modern thinking about the universe is the assumption that dynamics is an elemental feature that exists without question. However, ongoing research into the quantum nature of time is challenging this view: my recently introduced quantum theory of time suggests that dynamics may be a phenomenological consequence of a fundamental violation of time reversal symmetry. I show here that there is consistency between the new theory and the block universe view. I also discuss the new theory in relation to the human experience of existing in the present moment, able to reflect on the past and contemplate a future that is yet to happen.This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'. © 2018 The Authors.

Controlling spark timing for consecutive cycles to reduce the cyclic variations of SI engines

International Nuclear Information System (INIS)

Kaleli, Alirıza; Ceviz, Mehmet Akif; Erenturk, Köksal

2015-01-01

Minimization of the cyclic variations is one of the most important design goal for spark-ignited engines. Primary motivation of this study is to reduce the cyclic variations in spark ignition engines by controlling the spark timing for consecutive cycles. A stochastic model was performed between spark timing and in–cylinder maximum pressure by using the system identification techniques. The incylinder maximum pressure of the next cycle was predicted with this model. Minimum variance and generalized minimum variance controllers were designed to regulate the in–cylinder maximum pressure by changing the spark timing for consecutive cycles of the test engine. The produced control algorithms were built in LabView environment and installed to the Field Programmable Gate Arrays (FPGA) chassis. According to the test results, the in–cylinder maximum pressure of the next pressure cycle can be predicted fairly well, and the spark timing can be regulated to keep the in–cylinder maximum pressure in a desired band to reduce the cyclic variations. At fixed spark timing experiments, the COV Pmax and COV imep were 3.764 and 0.677%, whereas they decreased to 3.208 and 0.533% when GMV controller was applied, respectively. - Highlights: • Cycle per cycle spark timing control was carried out. • A stochastic process model was described between P max and the spark timing. • The cyclic variations in P max was decreased by keeping it in a desired band. • Different controllers were used to adjust spark timing signal of the next cycle. • COV Pmax was decreased by about 15% by using GMV controller

Time and space variations of trophosherive carbon dioxide over Japan

Energy Technology Data Exchange (ETDEWEB)

Tanaka, M.; Nakazawa, T.; Aoki, S.

Aircraft measurements of atmospheric CO/sub 2/ concentration over Japan, initiated in January 1979, have been continued to the present. The average seasonal variation of atmospheric CO/sub 2/ showed maximum concentration early in April and early in May, and minimum concentration in mid-August and mid-September for the lower-most and the upper-most layers of the troposphere, respectively. The peak-to-peak amplitudes of the seasonal variation were 14.5, 9.0 and 7.8 ppmv for the lower, middle and upper tropospheres, respectively. The average rate of annual increase of the CO/sub 2/ concentration over the last 6 years was about 1.3 ppmv yr/sup -1/ with considerable variation with time. The vertical profile of the annual mean value of the CO/sub 2/ concentration was almost the same from year to year; the CO/sub 2/ concentrations decreased gradually with height and the concentration difference between the lowest and highest layers of the troposphere was about 2 ppmv. (authors).

Time variations in geomagnetic intensity

Science.gov (United States)

Valet, Jean-Pierre

2003-03-01

After many years spent by paleomagnetists studying the directional behavior of the Earth's magnetic field at all possible timescales, detailed measurements of field intensity are now needed to document the variations of the entire vector and to analyze the time evolution of the field components. A significant step has been achieved by combining intensity records derived from archeological materials and from lava flows in order to extract the global field changes over the past 12 kyr. A second significant step was due to the emergence of coherent records of relative paleointensity using the remanent magnetization of sediments to retrace the evolution of the dipole field. A third step was the juxtaposition of these signals with those derived from cosmogenic isotopes. Contemporaneous with the acquisition of records, new techniques have been developed to constrain the geomagnetic origin of the signals. Much activity has also been devoted to improving the quality of determinations of absolute paleointensity from volcanic rocks with new materials, proper selection of samples, and investigations of complex changes in magnetization during laboratory experiments. Altogether these developments brought us from a situation where the field changes were restricted to the past 40 kyr to the emergence of a coherent picture of the changes in the geomagnetic dipole moment for at least the past 1 Myr. On longer timescales the field variability and its average behavior is relatively well documented for the past 400 Myr. Section 3 gives a summary of most methods and techniques that are presently used to track the field intensity changes in the past. In each case, current limits and potential promises are discussed. The section 4 describes the field variations measured so far over various timescales covered by the archeomagnetic and the paleomagnetic records. Preference has always been given to composite records and databases in order to extract and discuss major and global geomagnetic

Standardised Resting Time Prior to Blood Sampling and Diurnal Variation Associated with Risk of Patient Misclassification

DEFF Research Database (Denmark)

Bøgh Andersen, Ida; Brasen, Claus L.; Christensen, Henry

2015-01-01

.9×10-7) and sodium (p = 8.7×10-16). Only TSH and albumin were clinically significantly influenced by diurnal variation. Resting time had no clinically significant effect. CONCLUSIONS: We found no need for resting 15 minutes prior to blood sampling. However, diurnal variation was found to have a significant......BACKGROUND: According to current recommendations, blood samples should be taken in the morning after 15 minutes' resting time. Some components exhibit diurnal variation and in response to pressures to expand opening hours and reduce waiting time, the aims of this study were to investigate...... the impact of resting time prior to blood sampling and diurnal variation on biochemical components, including albumin, thyrotropin (TSH), total calcium and sodium in plasma. METHODS: All patients referred to an outpatient clinic for blood sampling were included in the period Nov 2011 until June 2014 (opening...

Physical activity and sedentary time: male perceptions in a university work environment.

Science.gov (United States)

George, Emma S; Kolt, Gregory S; Rosenkranz, Richard R; Guagliano, Justin M

2014-03-01

Promoting physical activity and reducing sedentary time in males can be challenging, and interventions tailored specifically for males are limited. Understanding male perceptions of physical activity and sedentary behavior is important to inform development of relevant interventions, especially for males working in an office setting. As part of a larger intervention study to increase physical activity and reduce sedentary time, male university employees aged 35 to 64 years were invited to partake in focus groups to discuss benefits, motivators, and barriers related to physical activity and sedentary time. Five semistructured focus group sessions, ranging from 50 to 70 minutes in duration, were conducted on two campuses at an Australian university. A total of 15 participants (9 academic/faculty staff and 6 professional staff), with a mean (± SD) age of 46.1 (±8.0) years took part in the study. Health and family were commonly discussed motivators for physical activity, whereas time constraints and work commitments were major barriers to physical activity participation. Sedentary time was a perceived "by-product" of participants' university employment, as a substantial proportion of their days were spent sitting, primarily at a computer. Participants believed that physical activity should be recognized as a legitimate activity at work, embedded within the university culture and endorsed using a top-down approach. It is important to encourage breaks in sedentary time and recognize physical activity as a legitimate health-promoting activity that is supported and encouraged during working hours. These findings can be used as a platform from which to develop targeted strategies to promote physical activity in male university employees.

Algebraic time-dependent variational approach to dynamical calculations

International Nuclear Information System (INIS)

Shi, S.; Rabitz, H.

1988-01-01

A set of time-dependent basis states is obtained with a group of unitary transformations generated by a Lie algebra. Applying the time-dependent variational principle to the trial function subspace constructed from the linear combination of the time-dependent basis states gives rise to a set of ''classical'' equations of motion for the group parameters and the expansion coefficients from which the time evolution of the system state can be determined. The formulation is developed for a general Lie algebra as well as for the commonly encountered algebra containing homogeneous polynominal products of the coordinate Q and momentum P operators (or equivalently the boson creation a/sup dagger/ and annihilation a operators) of order 0, 1, and 2. Explicit expressions for the transition amplitudes are derived by virtue of the cannonical transformation properties of the unitary transformation. The applicability of the present formalism in a variety of problems is implied by two illustrative examples: (a) a parametric amplifier; (b) the collinear collision of an atom with a Morse oscillator

Determining Time Variation of Cable Tension Forces in Suspended Bridges Using Time-Frequency Analysis

Directory of Open Access Journals (Sweden)

Gannon Stromquist-LeVoir

2018-01-01

Full Text Available A feasibility study was conducted to develop a novel method to determine the temporal changes of tensile forces in bridge suspender cables using time-frequency analysis of ambient vibration measurements. An analytical model of the suspender cables was developed to evaluate the power spectral density (PSD function of a cable with consideration of cable flexural stiffness. Discrete-time, short-time Fourier transform (STFT was utilized to analyze the recorded acceleration histories in both time and frequency domains. A mathematical convolution of the analytical PSD function and time-frequency data was completed to evaluate changes in cable tension force over time. The method was implemented using acceleration measurements collected from an in-service steel arch bridge with a suspended deck to calculate the temporal variation in cable forces from the vibration measurements. The observations served as proof of concept that the proposed method may be used for cable fatigue life calculations and bridge weigh-in-motion studies.

Universal Investment in Infants and Long-Run Health

DEFF Research Database (Denmark)

Hjort, Jonas; Sølvsten, Mikkel; Wüst, Miriam

2017-01-01

This paper examines the long-run health effects of a universal infant health intervention, the 1937 Danish home visiting program, which targeted all infants. Using administrative population data and exploiting variation in the timing of implementation across municipalities, we find that treated...

Universal Investment in Infants and Long-Run Health

DEFF Research Database (Denmark)

Hjort, Jonas; Sølvsten, Mikkel; Wüst, Miriam

This paper provides the first estimates of the long-run health effects of a universal infant health intervention. We examine the 1937 Danish home visiting program, which targeted all infants. Using administrative population data and exploiting variation in the timing of implementation across...

Continuous-Time Symmetric Hopfield Nets are Computationally Universal

Czech Academy of Sciences Publication Activity Database

Šíma, Jiří; Orponen, P.

2003-01-01

Roč. 15, č. 3 (2003), s. 693-733 ISSN 0899-7667 R&D Projects: GA AV ČR IAB2030007; GA ČR GA201/02/1456 Institutional research plan: AV0Z1030915 Keywords : continuous-time Hopfield network * Liapunov function * analog computation * computational power * Turing universality Subject RIV: BA - General Mathematics Impact factor: 2.747, year: 2003

Time variation of fluorescence lifetime in enhanced cyan fluorescence protein

International Nuclear Information System (INIS)

Lee, Soonhyouk; Kim, Soo Yong; Park, Kyoungsook; Jeong, Jinyoung; Chung, Bong Hyun; Kim, Sok Won

2010-01-01

The lifetime variations of enhanced cyan fluorescence protein (ECFP) in relatively short integration time bins were studied via time-correlated single photon counting (TCSPC) measurement. We observed that minimum photon counts are necessary for the lifetime estimation to achieve a certain range of variance. The conditions to decrease the variance of lifetime were investigated and the channel width of the measurement of TCSPC data was found to be another important factor for the variance of lifetime. Though the lifetime of ECFP is best fit by a double exponential, a mono exponential fit for the same integration time is more stable. The results may be useful in the analysis of photophysical dynamics for ensemble molecules in short measurement time windows.

Handheld mechanical nociceptive threshold testing in dairy cows - intra-individual variation, inter-observer agreement and variation over time.

Science.gov (United States)

Raundal, Peter M; Andersen, Pia H; Toft, Nils; Forkman, Björn; Munksgaard, Lene; Herskin, Mette S

2014-11-01

To examine the use of handheld methodology to assess mechanical nociceptive threshold (MNT) on cows kept loose-housed. Prospective randomized partial cross-over experimental study. A one-factor (test day) design was used to evaluate MNT over time. One hundred and fifteen healthy, loose-housed Danish Holstein cattle. We evaluated intra-individual variation, inter-observer agreement and variation over time of MNT using two handheld devices and two stimulation sites. Mechanical, ramped stimulations were performed with an algometer (6.5 mm diameter steel probe, 0-10.0 kgf) or an electronic von Frey device (plastic tip with diameter 0.8 mm, 0-1000 gf). Each cow received 5-6 consecutive stimulations within a 2 × 5 cm skin area on the dorsal or lateral aspect of the left third metatarsus until an avoidance reaction occurred. We investigated the difference in precision [expressed as coefficient of variation (CV)] between the combinations of devices and stimulation sites. The inter-observer agreement and the difference in MNT between test day 1, 3, 7, 10 and 24 were investigated for selected combinations. Data were analysed in mixed models and Bland-Altman as relevant. The CVs did not differ [range 0.34-0.52 (p = 0.1)]. Difference between observers (95% limits) was 0.2 kgf (2.8) and 4 gf (369) for the algometer and von Frey device, respectively. Mechanical nociceptive threshold increased from 361 on test day one to 495 gf on test day 24 (p < 0.01). All methods showed a high degree of intra-individual variation, and no combination of device and stimulation site showed superior precision. Mean difference between observers was low, and MNT was not consistent over time. Further development of the methods is required before they can be used in research to investigate possible relations between claw lesions and hyperalgesia. © 2014 The Authors Veterinary Anaesthesia and Analgesia published by John Wiley & Sons Ltd on behalf of Association of Veterinary Anaesthetists and the

Developmental stage of strongyle eggs affects the outcome variations of real-time PCR analysis

DEFF Research Database (Denmark)

Andersen, Ulla Vestergaard; Haakansson, I. T.; Roust, Tina

2013-01-01

extent developmental stages can affect the variation of diagnostic test results. This study investigated the influence of developmental stages of strongyle eggs on the variation real-time polymerase chain reaction (PCR) results. Mixed species strongyle eggs were obtained from the faeces of a naturally...

Clasp/SJ Observation of Time Variations of Lyman-Alpha Emissions in a Solar Active Region

Science.gov (United States)

Ishikawa, S.; Kubo, M.; Katsukawa, Y.; Kano, R.; Narukage, N.; Ishikawa, R.; Bando, T.; Winebarger, A.; Kobayashi, K.; Trujillo Bueno, J.;

The cosmological slingshot scenario: a stringy early times universe

Energy Technology Data Exchange (ETDEWEB)

Germani, Cristiano [D.A.M.T.P., Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Grandi, Nicolas [SISSA, via Beirut 4, 34014 Trieste (Italy); Kehagias, Alex [Physics Division, National Technical University of Athens, 15780 Zografou Campus, Athens (Greece)], E-mail: Germani@sissa.it, E-mail: grandi@fisica.unlp.edu.ar, E-mail: kehagias@central.ntua.gr

2008-07-07

A cosmological model for the early time universe is proposed. In this model, the universe is a wandering brane moving in a warped throat of a Calabi-Yau space. A nonzero angular momentum induces a turning point in the brane trajectory, and leads to a bouncing cosmology as experienced by an observer living on the brane. The universe undergoes a decelerated contraction followed by an accelerating expansion and no big-bang singularity. Although the number of e-folds of accelerated motion is low (less than 2), standard cosmological problems are not present in our model; thanks to the absence of an initial singularity and the violation of energy conditions of mirage matter at high energies. Density perturbations are also calculated in our model and we find a slightly red spectral index with negligible tensorial perturbations in compatibility with WMAP data.

A novel universal real-time PCR system using the attached universal duplex probes for quantitative analysis of nucleic acids

Directory of Open Access Journals (Sweden)

Wilson Zoe A

2008-06-01

Full Text Available Abstract Background Real-time PCR techniques are being widely used for nucleic acids analysis, but one limitation of current frequently employed real-time PCR is the high cost of the labeled probe for each target molecule. Results We describe a real-time PCR technique employing attached universal duplex probes (AUDP, which has the advantage of generating fluorescence by probe hydrolysis and strand displacement over current real-time PCR methods. AUDP involves one set of universal duplex probes in which the 5' end of the fluorescent probe (FP and a complementary quenching probe (QP lie in close proximity so that fluorescence can be quenched. The PCR primer pair with attached universal template (UT and the FP are identical to the UT sequence. We have shown that the AUDP technique can be used for detecting multiple target DNA sequences in both simplex and duplex real-time PCR assays for gene expression analysis, genotype identification, and genetically modified organism (GMO quantification with comparable sensitivity, reproducibility, and repeatability with other real-time PCR methods. Conclusion The results from GMO quantification, gene expression analysis, genotype identification, and GMO quantification using AUDP real-time PCR assays indicate that the AUDP real-time PCR technique has been successfully applied in nucleic acids analysis, and the developed AUDP real-time PCR technique will offer an alternative way for nucleic acid analysis with high efficiency, reliability, and flexibility at low cost.

An explicit solution for a renewal process with waiting time and its variational principle

International Nuclear Information System (INIS)

Lewins, J.D.

2001-01-01

The forward and backward equations for the conditional probability density are derived for a reliability system consisting of a single component whose repair is subject to a delay time in providing a spare part but whose mean rate of repair is otherwise constant and whose time to failure is exponentially distributed. Exact solutions are quoted. These equations are then shown to be an adjoint pair that provide stationary conditions for a variational principle, in elementary form, from which all properties of the systems can be predicted with an accuracy greater than that implied by the trial functions or approximations used. A second or specific form of variational principle provides specific estimates to questions at hand. The second or adjoint field in the first elementary principle is the backward Kolmogorov solution and the in the specific form is the importance function, as used in nuclear reactor theory. The solutions are given for long-time and in a recurrence relation form valid for all times so that approximate solutions can be checked. Approximations suitable for variational trial functions are given. Two examples give the effect of a change of delay time for a steady state and an initial transient, respectively

Dynamics of Gaussian Wigner functions derived from a time-dependent variational principle

Directory of Open Access Journals (Sweden)

Jens Aage Poulsen

2017-11-01

Full Text Available By using a time-dependent variational principle formulated for Wigner phase-space functions, we obtain the optimal time-evolution for two classes of Gaussian Wigner functions, namely those of either thawed real-valued or frozen but complex Gaussians. It is shown that tunneling effects are approximately included in both schemes.

Hybrid model for forecasting time series with trend, seasonal and salendar variation patterns

Science.gov (United States)

Suhartono; Rahayu, S. P.; Prastyo, D. D.; Wijayanti, D. G. P.; Juliyanto

2017-09-01

Most of the monthly time series data in economics and business in Indonesia and other Moslem countries not only contain trend and seasonal, but also affected by two types of calendar variation effects, i.e. the effect of the number of working days or trading and holiday effects. The purpose of this research is to develop a hybrid model or a combination of several forecasting models to predict time series that contain trend, seasonal and calendar variation patterns. This hybrid model is a combination of classical models (namely time series regression and ARIMA model) and/or modern methods (artificial intelligence method, i.e. Artificial Neural Networks). A simulation study was used to show that the proposed procedure for building the hybrid model could work well for forecasting time series with trend, seasonal and calendar variation patterns. Furthermore, the proposed hybrid model is applied for forecasting real data, i.e. monthly data about inflow and outflow of currency at Bank Indonesia. The results show that the hybrid model tend to provide more accurate forecasts than individual forecasting models. Moreover, this result is also in line with the third results of the M3 competition, i.e. the hybrid model on average provides a more accurate forecast than the individual model.

Universal behaviour in the stock market: Time dynamics of the electronic orderbook

Science.gov (United States)

Kızılersü, Ayşe; Kreer, Markus; Thomas, Anthony W.; Feindt, Michael

2016-07-01

A consequence of the digital revolution is that share trading at the stock exchange takes place via electronic order books which are accessed by traders and investors via the internet. Our empirical findings of the London Stock Exchange demonstrate that once ultra-high frequency manipulation on time scales less than around ten milliseconds is excluded, all relevant changes in the order book happen with time differences that are randomly distributed and well described by a left-truncated Weibull distribution with universal shape parameter (independent of time and same for all stocks). The universal shape parameter corresponds to maximum entropy of the distribution.

Variations in automatically recorded rumination time as explained by variations in intake of dietary fractions and milk production, and between-cow variation.

Science.gov (United States)

Byskov, M V; Nadeau, E; Johansson, B E O; Nørgaard, P

2015-06-01

Individual recording of rumination time (RT) is now possible in commercial dairy herds, through development of a microphone-based sensor, which is able to record RT by the sound of rumination activity. The objectives of this study were to examine the relationship between daily RT and intakes of different dietary fractions, the relationship between RT in minutes per kilogram of dry matter intake (DMI) and milk production, and to examine the variation in RT within and between mid-lactating dairy cows. Data from 3 production trials were used in which a total of 27 different diets were fed. The data contained 761, 290, and 203 daily recordings of RT, milk yield, milk components, DMI, and intake of dietary fractions recorded on 29, 26, and 24 Holstein and Swedish Red cows from trials 1, 2, and 3, respectively. The dietary fractions included forage neutral detergent fiber (NDF), concentrate NDF, crude protein, sugar, starch, and the remaining fraction represented by organic matter--(forage NDF+concentrate NDF+crude protein+sugar+starch). The relationship between the dietary fractions and RT was analyzed in 2 steps. In step 1, the dietary fractions, which were significantly related to RT, were selected and simultaneously checked for multicollinearity between the dietary components; in step 2, a multivariate model, including the effect of repeated measurements, the main effect of the selected dietary fractions from step 1, random effects of cow(trial) and trial, and information on breed, days in milk, and parity was used to analyze the relationship between RT and the selected dietary fractions. Relationships between RT in minutes per kilogram of DMI and milk yield and milk components were analyzed, using the same multivariate model as in step 2. Approximately 32% of the variation in daily RT could be explained by variations in intakes of the dietary fractions, whereas 48% of the total variation in RT was accounted for by individual variations between cows. Intakes of

Time variations of geomagnetic activity indices Kp and Ap: an update

Directory of Open Access Journals (Sweden)

G. K. Rangarajan

1997-10-01

Full Text Available Kp and Ap indices covering the period 1932 to 1995 are analysed in a fashion similar to that attempted by Bartels for the 1932–1961 epoch to examine the time variations in their characteristics. Modern analysis techniques on the extended data base are used for further insight. The relative frequencies of occurrence of Kp with different magnitudes and the seasonal and solar cycle dependences are seen to be remarkably consistent despite the addition of 35 years of observations. Many of the earlier features seen in the indices and special intervals are shown to be replicated in the present analysis. Time variations in the occurrence of prolonged periods of geomagnetic calm or of enhanced activity are presented and their relation to solar activity highlighted. It is shown that in the declining phase the occurrence frequencies of Kp = 4–5 (consecutively over 4 intervals can be used as a precursor for the maximum sunspot number to be expected in the next cycle. The semi-annual variation in geomagnetic activity is re-examined utilising not only the Ap index but also the occurrence frequencies of Kp index with different magnitudes. Lack of dependence of the amplitude of semi-annual variation on sunspot number is emphasised. Singular spectrum analysis of the mean monthly Ap index shows some distinct periodic components. The temporal evolution of ~44 month, ~21 month and ~16 month oscillations are examined and it is postulated that while QBO and the 16 month oscillations could be attributed to solar wind and IMF oscillations with analogous periodicity, the 44 month variation is associated with a similar periodicity in recurrent high speed stream caused by sector boundary passage. It is reconfirmed that there could have been only one epoch around 1940 when solar wind speed could have exhibited a 1.3-year periodicity comparable to that seen during the post-1986 period.

Time variations of geomagnetic activity indices Kp and Ap: an update

Directory of Open Access Journals (Sweden)

G. K. Rangarajan

Full Text Available Kp and Ap indices covering the period 1932 to 1995 are analysed in a fashion similar to that attempted by Bartels for the 1932–1961 epoch to examine the time variations in their characteristics. Modern analysis techniques on the extended data base are used for further insight. The relative frequencies of occurrence of Kp with different magnitudes and the seasonal and solar cycle dependences are seen to be remarkably consistent despite the addition of 35 years of observations. Many of the earlier features seen in the indices and special intervals are shown to be replicated in the present analysis. Time variations in the occurrence of prolonged periods of geomagnetic calm or of enhanced activity are presented and their relation to solar activity highlighted. It is shown that in the declining phase the occurrence frequencies of Kp = 4–5 (consecutively over 4 intervals can be used as a precursor for the maximum sunspot number to be expected in the next cycle. The semi-annual variation in geomagnetic activity is re-examined utilising not only the Ap index but also the occurrence frequencies of Kp index with different magnitudes. Lack of dependence of the amplitude of semi-annual variation on sunspot number is emphasised. Singular spectrum analysis of the mean monthly Ap index shows some distinct periodic components. The temporal evolution of ~44 month, ~21 month and ~16 month oscillations are examined and it is postulated that while QBO and the 16 month oscillations could be attributed to solar wind and IMF oscillations with analogous periodicity, the 44 month variation is associated with a similar periodicity in recurrent high speed stream caused by sector boundary passage. It is reconfirmed that there could have been only one epoch around 1940 when solar wind speed could have exhibited a 1.3-year periodicity comparable to that seen during the post-1986 period.

Time variations in the mechanical characteristics of local crustal segments according to seismic observations

Science.gov (United States)

Kocharyan, G. G.; Gamburtseva, N. G.; Sanina, I. A.; Danilova, T. V.; Nesterkina, M. A.; Gorbunova, E. M.; Ivanchenko, G. N.

2011-04-01

The results of the seismic observations made with two different experimental setups are presented. In the first case, the signals produced by underground nuclear explosions at the Semipalatinsk Test Site were measured on a linear profile, which allowed one to definitely outline the areas where the mechanical properties of rocks experienced considerable time variations. In the second case, the waves excited by the open-pit mine blasts recorded at a small-aperture seismic array at the Mikhnevo Geophysical Station (Institute of Geosphere Dynamics, Russian Academy of Sciences) on the East European Platform favored the estimation of variations in the integral characteristics of the seismic path. Measurements in aseismic regions characterized by diverse geological structure and different tectonic conditions revealed similar effects of the strong dependency of seismic parameters on the time of explosions. Here, the variations experienced by the maximum amplitudes of oscillations and irrelevant to seasonal changes or local conditions reached a factor of two. The generic periods of these variations including the distinct annual rhythm are probably the fragments of a lower-frequency process. The obtained results suggest that these variations are due to changes in the stressstrain state of active fault zones, which, in turn, can be associated with the macroscale motion of large blocks triggered by tidal strains, tectonic forces and, possibly, variations in the rate of the Earth's rotation.

Time variations of hf induced plasma waves

International Nuclear Information System (INIS)

Showen, R.L.

1976-01-01

Intense plasma waves are generated by an HF pump wave in an ionospheric heating experiment at the Arecibo Observatory. These plasma waves can be observed as enhancements to the ion and plasma lines of the incoherent backscatter echo. The enhancements can be three or four orders of magnitude more intense than the unenhanced lines, and tend to fluctuate wildly. Both the purely growing and the decay mode parametric instabilities are present. When the pump wave is turned on abruptly the enhancements develop in time in a repeatable manner. A rather remarkable feature on time scales of seconds is an overshoot in instability power. These overshoots occur frequently but not universally and last for 1 to 6 seconds. They can have a magnitude from ten to hundreds of times the average instability level. Field aligned irregularities may be the cause of the overshoots. The overshoots appear definitely related to an unusually rapid rise in measured electron temperature that cannot be understood in terms of ohmic energy deposition. On time scales of milliseconds there is a ''mini-overshoot'' before the growth of the instability to a large value. The spectral details also change in a striking manner. The instabilities can first be detected 2 to 4 msec after the pump wave turn-on. The decay mode is present as well as a broad featureless ''noise bump'', which partially sharpens into a line as time progresses. These changes of the spectra in time seem to run counter to the currently accepted theories of plasma wave saturation

Long-term and transient time variation of cosmic ray fluxes detected in Argentina by CARPET cosmic ray detector

Science.gov (United States)

De Mendonça, R. R. S.; Raulin, J.-P.; Bertoni, F. C. P.; Echer, E.; Makhmutov, V. S.; Fernandez, G.

2011-07-01

We present results obtained at El Leoncito (CASLEO, San Juan, Argentina) with the CARPET charged particles detector installed in April 2006. The observed modulation of the cosmic ray flux is discussed as a function of its time variability and it is related to longer solar activity variations and to shorter variations during solar and geomagnetic transient activity. Short period (few minutes, few hours) cosmic ray modulation events are observed during rain time (precipitation) and significant variations of the atmospheric electric field. Complementary observations of the atmospheric electric field indicate that its time variations play an important role in the detected cosmic ray event.

Does Shortened Application Time Affect Long-Term Bond Strength of Universal Adhesives to Dentin?

Science.gov (United States)

Saikaew, P; Matsumoto, M; Chowdhury, Afma; Carvalho, R M; Sano, H

2018-04-09

This study evaluated the effect of shortened application time on long-term bond strength with universal adhesives. Three universal adhesives were used: Clearfil Universal Bond (CU, Kuraray Noritake Dental Inc, Tokyo, Japan), Scotchbond Universal Adhesive (SB, 3M ESPE, St Paul, MN, USA) or G-Premio Bond (GP, GC Corp, Tokyo, Japan). Sixty molars were cut to expose midcoronal dentin and prepared with a regular diamond bur. Each adhesive was applied either according to the manufacturer's instruction or with shortened time. Specimens were stored in distilled water at 37°C for 24 hours and then cut into resin-dentin sticks. Microtensile bond strength (μTBS) was tested after either 24 hours or 1 year of water storage. Data were analyzed by the three-way ANOVA and Duncan tests ( α=0.05). Fracture modes were analyzed under a scanning electron microscope (SEM). One dentin stick per group was selected after fracture mode analysis and further observed using transmission electron microscopy (TEM). Six additional dentin discs were prepared and conditioned with each adhesive under the different application time to observe the adhesive-smear layer interaction by SEM. Shortened application time affected the μTBS ( puniversal adhesives to bur-cut dentin. The performance of universal adhesives can be compromised when applied using a shortened application time.

Geometrical treatment of non-potential interactions: the exterior variational calculus, dynamical systems, physical 1-forms and variational selfadjointness

International Nuclear Information System (INIS)

Trostel, R.

1982-01-01

A mathematical objective of this paper is to provide geometrical formulation of the integrability conditions for the existence of an action functional, that is, to provide a geometrical counterpart (similar to that by Abraham, Marsden, and Hughes) of the variational and functional approach to self-adjointness. This objective is achieved via the exterior variational calculus, an exterior differential calculus on the vector space of functions depending on time or space time, using from the outset extensively the concept of functional differentiation as its foundation. Variational self-adjointness equals the variational closure of the physical 1-form, the vanishing of a generalized curl-operation applied to the equations of motion. The convenience of this more formal approach is demonstrated, not only when deriving the conditions of variational self-adjointness for materials of differential type of arbitrary order (particles or fields), using roughly no more than Dirac's delta-distributions, but also when treating materials of a broader class (including causal and acausal constitutive functionals, materials of rate type, integral type, etc.). A physical objective of this paper is achieved by pointing out that, as physics is primarily concerned with the solutions of the evolution equations, i.e., with the set of the zero points of the physical 1-form, an equivalence relation among the physical 1-forms on the infinite dimensional vector space of functions is constructed by leaving the set of their zero points unchanged. Using this result, a direct Lagrangian universality is indicated and an almost one presented. Moreover, all physical 1-forms connected by invertible supermatrices (thus mixing the evolution law of different times or space-time) are equivalent. Choosing these supermatrices to be diagonal in time or space-time yields the indirect analytical representation factors

Time Variations of Observed H α Line Profiles and Precipitation Depths of Nonthermal Electrons in a Solar Flare

Energy Technology Data Exchange (ETDEWEB)

Falewicz, Robert; Radziszewski, Krzysztof; Rudawy, Paweł; Berlicki, Arkadiusz, E-mail: falewicz@astro.uni.wroc.pl, E-mail: radziszewski@astro.uni.wroc.pl, E-mail: rudawy@astro.uni.wroc.pl, E-mail: berlicki@astro.uni.wroc.pl [Astronomical Institute, University of Wrocław, 51-622 Wrocław, ul. Kopernika 11 (Poland)

2017-10-01

We compare time variations of the H α and X-ray emissions observed during the pre-impulsive and impulsive phases of the C1.1-class solar flare on 2013 June 21 with those of plasma parameters and synthesized X-ray emission from a 1D hydrodynamic numerical model of the flare. The numerical model was calculated assuming that the external energy is delivered to the flaring loop by nonthermal electrons (NTEs). The H α spectra and images were obtained using the Multi-channel Subtractive Double Pass spectrograph with a time resolution of 50 ms. The X-ray fluxes and spectra were recorded by RHESSI . Pre-flare geometric and thermodynamic parameters of the model and the delivered energy were estimated using RHESSI data. The time variations of the X-ray light curves in various energy bands and those of the H α intensities and line profiles were well correlated. The timescales of the observed variations agree with the calculated variations of the plasma parameters in the flaring loop footpoints, reflecting the time variations of the vertical extent of the energy deposition layer. Our result shows that the fast time variations of the H α emission of the flaring kernels can be explained by momentary changes of the deposited energy flux and the variations of the penetration depths of the NTEs.

Handheld mechanical nociceptive threshold testing in dairy cows – intra-individual variation, inter-observer agreement and variation over time

Science.gov (United States)

Raundal, Peter M; Andersen, Pia H; Toft, Nils; Forkman, Björn; Munksgaard, Lene; Herskin, Mette S

2014-01-01

Objective To examine the use of handheld methodology to assess mechanical nociceptive threshold (MNT) on cows kept loose-housed. Study design Prospective randomized partial cross-over experimental study. A one-factor (test day) design was used to evaluate MNT over time. Animals One hundred and fifteen healthy, loose-housed Danish Holstein cattle. Methods We evaluated intra-individual variation, inter-observer agreement and variation over time of MNT using two handheld devices and two stimulation sites. Mechanical, ramped stimulations were performed with an algometer (6.5 mm diameter steel probe, 0–10.0 kgf) or an electronic von Frey device (plastic tip with diameter 0.8 mm, 0–1000 gf). Each cow received 5–6 consecutive stimulations within a 2 × 5 cm skin area on the dorsal or lateral aspect of the left third metatarsus until an avoidance reaction occurred. We investigated the difference in precision [expressed as coefficient of variation (CV)] between the combinations of devices and stimulation sites. The inter-observer agreement and the difference in MNT between test day 1, 3, 7, 10 and 24 were investigated for selected combinations. Data were analysed in mixed models and Bland-Altman as relevant. Results The CVs did not differ [range 0.34–0.52 (p = 0.1)]. Difference between observers (95% limits) was 0.2 kgf (2.8) and 4 gf (369) for the algometer and von Frey device, respectively. Mechanical nociceptive threshold increased from 361 on test day one to 495 gf on test day 24 (p < 0.01). Conclusion and clinical relevance All methods showed a high degree of intra-individual variation, and no combination of device and stimulation site showed superior precision. Mean difference between observers was low, and MNT was not consistent over time. Further development of the methods is required before they can be used in research to investigate possible relations between claw lesions and hyperalgesia. PMID:24734991

Universal time-dependence of the mean-square displacement in extremely rugged energy landscapes with equal minima

DEFF Research Database (Denmark)

Dyre, Jeppe; Jacobsen, Jacob M.

1995-01-01

This paper presents a calculation of the time dependence of the mean-square displacement for symmetric random energy barrier hopping models at low temperatures, where the frequency dependence of the normalized diffusion constant D-tilde becomes universal, i.e., independent of the energy barrier...... probability distribution [J. C. Dyre, Phys. Rev. B 49, 11 709 (1994)]. The universal time dependence of the mean-square displacement is calculated from the effective medium approximation (EMA) universality equation, D-tilde lnD-tilde=s-tilde, where s-tilde is the dimensionless imaginary frequency, as well...... as for the approximation to the EMA universality equation D-tilde~=s-tilde/ln(1+s-tilde). At long times the universal mean-square displacement is linear in time, corresponding to ordinary diffusion, whereas the mean-square displacement at short times t in dimensionless units varies as 2/ln(t-1)....

Multitasking, but for What Benefit? The Dilemma Facing Nigerian University Students Regarding Part-Time Working

Science.gov (United States)

Gbadamosi, Gbolahan; Evans, Carl; Obalola, Musa Adebayo

2016-01-01

Students working part-time while studying for a full-time university degree are commonplace in many Western countries. This paper, however, examines the historically uncommon part-time working activities and career aspirations among Nigerian university students. In particular, how working is perceived to contribute to developing employability…

Temporal variations in elemental concentrations of atmospheric aerosols in Mexico City

International Nuclear Information System (INIS)

Aldape U, F.

1992-05-01

Measurements are reported of elemental concentrations of airborne particulates in Mexico City and their time variation over a one-week period in the spring of 1988. Proton-induced X-ray emission analysis, PIXE, was used to analyse the atmospheric aerosols which were bombarded with 2.5 MeV protons from the 12 MV Tandem Van de Graaff accelerator at the National Institute of Nuclear Research, ININ. Variations in the elemental concentrations were observed over the time period studied. An intercomparison was made in the case of the element lead with PIXE results obtained at the Crocker Nuclear Laboratory, CNL, University of California for the same set of samples. Excellent agreement was obtained both for the time variation of the relative concentration and the absolute lead concentrations. These results give added confidence to the protocol adopted at ININ. (Author)

Variation in the timing of reproduction of the four-striped field mouse ...

African Journals Online (AJOL)

Variation in the timing of reproduction of the four-striped field mouse, Rhabdomys pumilio , in ... Open Access DOWNLOAD FULL TEXT ... We used the four-striped field mouse, Rhabdomys pumilio (Sparrmann, 1784), to test the hypothesis that ...

Stochastic nonlinear time series forecasting using time-delay reservoir computers: performance and universality.

Science.gov (United States)

Grigoryeva, Lyudmila; Henriques, Julie; Larger, Laurent; Ortega, Juan-Pablo

2014-07-01

Reservoir computing is a recently introduced machine learning paradigm that has already shown excellent performances in the processing of empirical data. We study a particular kind of reservoir computers called time-delay reservoirs that are constructed out of the sampling of the solution of a time-delay differential equation and show their good performance in the forecasting of the conditional covariances associated to multivariate discrete-time nonlinear stochastic processes of VEC-GARCH type as well as in the prediction of factual daily market realized volatilities computed with intraday quotes, using as training input daily log-return series of moderate size. We tackle some problems associated to the lack of task-universality for individually operating reservoirs and propose a solution based on the use of parallel arrays of time-delay reservoirs. Copyright © 2014 Elsevier Ltd. All rights reserved.

TRANSIT TIMING OBSERVATIONS FROM KEPLER. V. TRANSIT TIMING VARIATION CANDIDATES IN THE FIRST SIXTEEN MONTHS FROM POLYNOMIAL MODELS

Energy Technology Data Exchange (ETDEWEB)

Ford, Eric B. [Astronomy Department, University of Florida, 211 Bryant Space Sciences Center, Gainesville, FL 32111 (United States); Ragozzine, Darin; Holman, Matthew J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Rowe, Jason F.; Barclay, Thomas; Borucki, William J.; Bryson, Stephen T.; Caldwell, Douglas A.; Kinemuchi, Karen; Koch, David G.; Lissauer, Jack J.; Still, Martin; Tenenbaum, Peter [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Steffen, Jason H. [Fermilab Center for Particle Astrophysics, P.O. Box 500, MS 127, Batavia, IL 60510 (United States); Batalha, Natalie M. [Department of Physics and Astronomy, San Jose State University, San Jose, CA 95192 (United States); Fabrycky, Daniel C. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Gautier, Thomas N. [Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA 91109 (United States); Ibrahim, Khadeejah A.; Uddin, Kamal [Orbital Sciences Corporation/NASA Ames Research Center, Moffett Field, CA 94035 (United States); Kjeldsen, Hans, E-mail: eford@astro.ufl.edu [Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark); and others

2012-09-10

Transit timing variations provide a powerful tool for confirming and characterizing transiting planets, as well as detecting non-transiting planets. We report the results of an updated transit timing variation (TTV) analysis for 1481 planet candidates based on transit times measured during the first sixteen months of Kepler observations. We present 39 strong TTV candidates based on long-term trends (2.8% of suitable data sets). We present another 136 weaker TTV candidates (9.8% of suitable data sets) based on the excess scatter of TTV measurements about a linear ephemeris. We anticipate that several of these planet candidates could be confirmed and perhaps characterized with more detailed TTV analyses using publicly available Kepler observations. For many others, Kepler has observed a long-term TTV trend, but an extended Kepler mission will be required to characterize the system via TTVs. We find that the occurrence rate of planet candidates that show TTVs is significantly increased ({approx}68%) for planet candidates transiting stars with multiple transiting planet candidates when compared to planet candidates transiting stars with a single transiting planet candidate.

Towards Uniform Accelerometry Analysis: A Standardization Methodology to Minimize Measurement Bias Due to Systematic Accelerometer Wear-Time Variation

Directory of Open Access Journals (Sweden)

Tarun R. Katapally, Nazeem Muhajarine

2014-06-01

Full Text Available Accelerometers are predominantly used to objectively measure the entire range of activity intensities – sedentary behaviour (SED, light physical activity (LPA and moderate to vigorous physical activity (MVPA. However, studies consistently report results without accounting for systematic accelerometer wear-time variation (within and between participants, jeopardizing the validity of these results. This study describes the development of a standardization methodology to understand and minimize measurement bias due to wear-time variation. Accelerometry is generally conducted over seven consecutive days, with participants' data being commonly considered 'valid' only if wear-time is at least 10 hours/day. However, even within ‘valid’ data, there could be systematic wear-time variation. To explore this variation, accelerometer data of Smart Cities, Healthy Kids study (www.smartcitieshealthykids.com were analyzed descriptively and with repeated measures multivariate analysis of variance (MANOVA. Subsequently, a standardization method was developed, where case-specific observed wear-time is controlled to an analyst specified time period. Next, case-specific accelerometer data are interpolated to this controlled wear-time to produce standardized variables. To understand discrepancies owing to wear-time variation, all analyses were conducted pre- and post-standardization. Descriptive analyses revealed systematic wear-time variation, both between and within participants. Pre- and post-standardized descriptive analyses of SED, LPA and MVPA revealed a persistent and often significant trend of wear-time’s influence on activity. SED was consistently higher on weekdays before standardization; however, this trend was reversed post-standardization. Even though MVPA was significantly higher on weekdays both pre- and post-standardization, the magnitude of this difference decreased post-standardization. Multivariable analyses with standardized SED, LPA and

Novel crystal timing calibration method based on total variation

Science.gov (United States)

Yu, Xingjian; Isobe, Takashi; Watanabe, Mitsuo; Liu, Huafeng

2016-11-01

A novel crystal timing calibration method based on total variation (TV), abbreviated as ‘TV merge’, has been developed for a high-resolution positron emission tomography (PET) system. The proposed method was developed for a system with a large number of crystals, it can provide timing calibration at the crystal level. In the proposed method, the timing calibration process was formulated as a linear problem. To robustly optimize the timing resolution, a TV constraint was added to the linear equation. Moreover, to solve the computer memory problem associated with the calculation of the timing calibration factors for systems with a large number of crystals, the merge component was used for obtaining the crystal level timing calibration values. Compared with other conventional methods, the data measured from a standard cylindrical phantom filled with a radioisotope solution was sufficient for performing a high-precision crystal-level timing calibration. In this paper, both simulation and experimental studies were performed to demonstrate the effectiveness and robustness of the TV merge method. We compare the timing resolutions of a 22Na point source, which was located in the field of view (FOV) of the brain PET system, with various calibration techniques. After implementing the TV merge method, the timing resolution improved from 3.34 ns at full width at half maximum (FWHM) to 2.31 ns FWHM.

Planck intermediate results. XXIV. Constraints on variation of fundamental constants

CERN Document Server

Ade, P A R; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Battaner, E.; Benabed, K.; Benoit-Levy, A.; Bernard, J.P.; Bersanelli, M.; Bielewicz, P.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Burigana, C.; Butler, R.C.; Calabrese, E.; Chamballu, A.; Chiang, H.C.; Christensen, P.R.; Clements, D.L.; Colombo, L.P.L.; Couchot, F.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Diego, J.M.; Dole, H.; Dore, O.; Dupac, X.; Ensslin, T.A.; Eriksen, H.K.; Fabre, O.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Gonzalez-Nuevo, J.; Gorski, K.M.; Gregorio, A.; Gruppuso, A.; Hansen, F.K.; Hanson, D.; Harrison, D.L.; Henrot-Versille, S.; Hernandez-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Jaffe, A.H.; Jones, W.C.; Keihanen, E.; Keskitalo, R.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lamarre, J.M.; Lasenby, A.; Lawrence, C.R.; Leonardi, R.; Lesgourgues, J.; Liguori, M.; Lilje, P.B.; Linden-Vornle, M.; Lopez-Caniego, M.; Lubin, P.M.; Macias-Perez, J.F.; Mandolesi, N.; Maris, M.; Martin, P.G.; Martinez-Gonzalez, E.; Masi, S.; Matarrese, S.; Mazzotta, P.; Meinhold, P.R.; Melchiorri, A.; Mendes, L.; Menegoni, E.; Mennella, A.; Migliaccio, M.; Miville-Deschenes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Moss, A.; Munshi, D.; Murphy, J.A.; Naselsky, P.; Nati, F.; Natoli, P.; Norgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C.A.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Pratt, G.W.; Prunet, S.; Rachen, J.P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Ristorcelli, I.; Rocha, G.; Roudier, G.; Rusholme, B.; Sandri, M.; Savini, G.; Scott, D.; Spencer, L.D.; Stolyarov, V.; Sudiwala, R.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Uzan, J.P.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L.A.; Yvon, D.; Zacchei, A.; Zonca, A.

2015-01-01

Any variation of the fundamental physical constants, and more particularly of the fine structure constant, $\\alpha$, or of the mass of the electron, $m_e$, would affect the recombination history of the Universe and cause an imprint on the cosmic microwave background angular power spectra. We show that the Planck data allow one to improve the constraint on the time variation of the fine structure constant at redshift $z\\sim 10^3$ by about a factor of 5 compared to WMAP data, as well as to break the degeneracy with the Hubble constant, $H_0$. In addition to $\\alpha$, we can set a constraint on the variation of the mass of the electron, $m_{\\rm e}$, and on the simultaneous variation of the two constants. We examine in detail the degeneracies between fundamental constants and the cosmological parameters, in order to compare the limits obtained from Planck and WMAP and to determine the constraining power gained by including other cosmological probes. We conclude that independent time variations of the fine structu...

Determinants of PhD Completion Time at the University of Ibadan ...

African Journals Online (AJOL)

Apart from conducting an extensive exploratory analysis on PhD production in the university, a binary logistic regression model was also fitted. The dichotomous responses were: completion on time and completion over time. The fitted logistic regression shows that only 10% of PhDs have predicted probability of completion ...

Oscillation effects and time variation of the supernova neutrino signal

Science.gov (United States)

Kneller, James P.; McLaughlin, Gail C.; Brockman, Justin

2008-02-01

The neutrinos detected from the next galactic core-collapse supernova will contain valuable information on the internal dynamics of the explosion. One mechanism leading to a temporal evolution of the neutrino signal is the variation of the induced neutrino flavor mixing driven by changes in the density profile. With one and two-dimensional hydrodynamical simulations we identify the behavior and properties of prominent features of the explosion. Using these results we demonstrate the time variation of the neutrino crossing probabilities due to changes in the Mikheyev-Smirnov-Wolfenstein (MSW) neutrino transformations as the star explodes by using the S-matrix—Monte Carlo—approach to neutrino propagation. After adopting spectra for the neutrinos emitted from the proto-neutron star we calculate for a galactic supernova the evolution of the positron spectra within a water Cerenkov detector and find that this signal allows us to probe of a number of explosion features.

Highly accurate bound state calculations of the two-center molecular ions by using the universal variational expansion for three-body systems

Science.gov (United States)

Frolov, Alexei M.

2018-03-01

The universal variational expansion for the non-relativistic three-body systems is explicitly constructed. This universal expansion can be used to perform highly accurate numerical computations of the bound state spectra in various three-body systems, including Coulomb three-body systems with arbitrary particle masses and electric charges. Our main interest is related to the adiabatic three-body systems which contain one bound electron and two heavy nuclei of hydrogen isotopes: the protium p, deuterium d and tritium t. We also consider the analogous (model) hydrogen ion ∞H2+ with the two infinitely heavy nuclei.

Evolution of gravitational orbits in the expanding universe

International Nuclear Information System (INIS)

Sereno, Mauro; Jetzer, Philippe

2007-01-01

The gravitational action of the smooth energy-matter components filling in the universe can affect the orbit of a planetary system. Changes are related to the acceleration of the cosmological scale size R. In a universe with significant dark matter, a gravitational system expands or contracts according to the amount and equation of state of the dark energy. At present time, the Solar System, according to the ΛCDM scenario emerging from observational cosmology, should be expanding if we consider only the effect of the cosmological background. Its fate is determined by the equation of state of the dark energy alone. The mean motion and periastron precession of a planet are directly sensitive to Re/R, whereas variations with time in the semimajor axis and eccentricity are related to its time variation. Actual bounds on the cosmological deceleration parameters q 0 from accurate astrometric data of perihelion precession and changes in the third Kepler's law in the Solar System fall short of 10 orders of magnitude with respect to estimates from observational cosmology. Future radio-ranging measurements of outer planets could improve actual bounds by 5 orders of magnitude

Trends in cosmology: Universal truths

International Nuclear Information System (INIS)

Horgan, J.

1990-01-01

In June more than 30 prominent cosmologist, astronomers and physicists gathered for six days at an isolated resort in northern Sweden. Their topic: the origin of the universe. While most agreed the big bang theory is still sound, new data are challenging a more detailed scenario: the cold dark matter model. Recent observations are squeezing this model from two sides. First, ever more sensitive probes of the so-called cosmic microwave background, a cool bath of microwaves that is thought to be the faint afterglow of the big bang, have yet to reveal any regional variations in intensity. That has forced modelers to assume the early universe was exceptionally smooth, or homogeneous, with matter spread uniformly through space. At the same time, maps of the universe have revealed ever larger thickets of galaxies surrounded by larger voids. If the universe was so smooth early on, how did it come to be so clumpy? This article addresses how cosmologist at this meeting addressed the big questions

Controlling cyclic combustion timing variations using a symbol-statistics predictive approach in an HCCI engine

International Nuclear Information System (INIS)

Ghazimirsaied, Ahmad; Koch, Charles Robert

2012-01-01

Highlights: ► Misfire reduction in a combustion engine based on chaotic theory methods. ► Chaotic theory analysis of cyclic variation of a HCCI engine near misfire. ► Symbol sequence approach is used to predict ignition timing one cycle-ahead. ► Prediction is combined with feedback control to lower HCCI combustion variation. ► Feedback control extends the HCCI operating range into the misfire region. -- Abstract: Cyclic variation of a Homogeneous Charge Compression Ignition (HCCI) engine near misfire is analyzed using chaotic theory methods and feedback control is used to stabilize high cyclic variations. Variation of consecutive cycles of θ Pmax (the crank angle of maximum cylinder pressure over an engine cycle) for a Primary Reference Fuel engine is analyzed near misfire operation for five test points with similar conditions but different octane numbers. The return map of the time series of θ Pmax at each combustion cycle reveals the deterministic and random portions of the dynamics near misfire for this HCCI engine. A symbol-statistic approach is used to predict θ Pmax one cycle-ahead. Predicted θ Pmax has similar dynamical behavior to the experimental measurements. Based on this cycle ahead prediction, and using fuel octane as the input, feedback control is used to stabilize the instability of θ Pmax variations at this engine condition near misfire.

Storm time variation of radiative cooling of thermosphere by nitric oxide emission

Science.gov (United States)

Krishna, M. V. Sunil; Bag, Tikemani; Bharti, Gaurav

2016-07-01

The fundamental vibration-rotation band emission (Δν=1, Δ j=0,± 1) by nitric oxide (NO) at 5.3 µm is one of the most important cooling mechanisms in thermosphere. The collisional vibrational excitation of NO(ν=0) by impact with atomic oxygen is the main source of vibrationally excited nitric oxide. The variation of NO density depends on latitude, longitude and season. The present study aims to understand how the radiative flux gets influenced by the severe geomagnetic storm conditions. The variation of Nitric Oxide (NO) radiative flux exiting thermosphere is studied during the superstorm event of 7-12 November, 2004. The observations of TIMED/SABER suggest a strong anti-correlation with the O/N_2 ratio observed by GUVI during the same period. On a global scale the NO radiative flux showed an enhancement during the main phase on 8 November, 2004, whereas maximum depletion in O/N_2 is observed on 10 November, 2004. Both O/N_2 and NO radiative flux were found to propagate equatorward due to the effect of meridional wind resulting from joule and particle heating in polar region. Larger penetrations is observed in western longitude sectors. These observed variations are effectively connected to the variations in neutral densities. In the equatorial sectors, O/N_2 shows enhancement but almost no variation in radiative flux is observed. The possible reasons for the observed variations in NO radiative emission and O/N_2 ratios are discussed in the light of equator ward increase in the densities and prompt penetration.

Simple model of variation of the signature of a space-time metric

International Nuclear Information System (INIS)

Konstantinov, M.Yu.

2004-01-01

The problem on the changes in the space-time signature metrics is discussed. The simple model, wherein the space-time metrics signature is determined by the nonlinear scalar field, is proposed. It is shown that both classical and quantum description of changes in the metrics signature is possible within the frames of the considered model; the most characteristic peculiarities and variations of the classical and quantum descriptions are also briefly noted [ru

Time Variations of Macrostickies and Extractable Stickies Concentrations in Deinking

OpenAIRE

MacNeil, Donald; Miranda Carreño, Rubén; Monte Lara, María Concepción; Blanco Suárez, Ángeles; Sundberg, Anna

2010-01-01

The stickies content, both macrostickies and stickies extractable in a solvent, was determined for samples taken at short time intervals from deinking lines, producing deinked pulp for newsprint production. The study was carried out at three mills on different continents, with each having a different source of recycled paper as raw material. The short-term variations in extractable stickies in the incoming raw material were quite extreme, with differences of 100% being seen within hours. Desp...

Time variations of macro and extractable stickies concentrations in deinking

OpenAIRE

McNeil, Donald; Miranda Carreño, Rubén; Concepción Lara, María Concepción; Blanco Suárez, Ángeles; Sundberg, Anna

2010-01-01

The stickies content, both macrostickies and stickies extractable in a solvent, was determined for samples taken at short time intervals from deinking lines producing deinked pulp for newsprint production. The study was carried out at three mills on different continents, with each having a different source of recycled paper as raw material. The short-term variations in extractable stickies in the incoming raw material were quite extreme, with differences of 100% being seen within hours. Despi...

Time variations of the angular momentum of the sun

International Nuclear Information System (INIS)

Schatten, K.H.

1977-01-01

Time variations of density models of the Sun are investigated. This is an attempt to estimate the changing moment of inertia of the Sun in order to calculate the internal solar angular velocity based upon Newton's equation of motion. Previous estimates of dI/dt disagree with those based upon central densities in a homologously contracting model. It is shown that the homologously contracting model leads to large errors in dI/dt. Based upon an integration of Sears's solar model, dI/dt=-5.5 x 10 34 gm cm 2 s -1 . This suggests a core angular velocity of /sub thetar-italic/ = (0.15 +- 0.03) x 10 -3 s -1 , corresponding to a period of 0.5 +- 0.1 days, assuming a constant angular velocity with time. The brackets indicate a weighting which is discussed

Periodical climate variations and their impact on Earth rotation for the last 800Kyr

Science.gov (United States)

Chapanov, Yavor; Gambis, Daniel

2010-05-01

The Earth rotation variations are highly affected by climatic variations associated with the glacial cycles in the late Pleistocene. The processes of glaciation, followed by ice melting, are connected with significant changes of the mean sea level. These processes redistribute great amount of water masses between oceans and ice sheets, which lead to changes of the axial moment of inertia and corresponding variations of the Universal Time UT1 and Length of Day LOD, according to the law of angular momentum conservation. The climatic variations for the last 800Kyr are analyzed by means of time series of temperature changes, determined by deuterium data from Antarctica ice core. Reconstructed glacial sea level variations for the last 380Kyr, determined by the sediments from the Red sea, are used, too. Common periodicities of the temperature and mean sea level variations are determined. Time series of the long-periodical UT1 and LOD oscillations for the last 380Kyr and 800Kyr are reconstructed by means of empirical hydrological model of global water redistribution between the ocean and ice sheets during the last glacial events.

Spanish version of the Time Management Behavior Questionnaire for university students.

Science.gov (United States)

García-Ros, Rafael; Pérez-González, Francisco

2012-11-01

The main objective of the study is to analyze the psychometric properties and predictive capacity on academic performance in university contexts of a Spanish adaptation of the Time Management Behavior Questionnaire. The scale was applied to 462 students newly admitted at the Universitat de València in the 2006-2007 school year. The analyses performed made it possible to reproduce the factorial structure of the original version of the questionnaire with slight modifications in the ascription of various items. The underlying factorial structure includes four interrelated dimensions (Establishing objectives and priorities, Time management tools, Perception of time control and Preference for disorganization), which present satisfactory levels of reliability and an adequate convergent validity with the Time management subscale of the Motivated Strategies for Learning Questionnaire. The scores on the dimensions of time management show significant levels of association with academic performance in the first year of university studies, especially highlighting the predictive capacity of the subscale dealing with the Establishment of objectives and priorities. These results show the reliability and validity of this adaptation of the scale for evaluating how the students manage their academic time, and predicting their performance in the year they initiate the degree program, thus aiding in the development of intervention proposals directed towards improving these skills.

Variation in aluminium patch test reactivity over time.

Science.gov (United States)

Siemund, Ingrid; Mowitz, Martin; Zimerson, Erik; Bruze, Magnus; Hindsén, Monica

2017-11-01

Contact allergy to aluminium has been reported more frequently in recent years. It has been pointed out that positive patch test reactions to aluminium may not be reproducible on retesting. To investigate possible variations in patch test reactivity to aluminium over time. Twenty-one adults, who had previously reacted positively to aluminium, were patch tested with equimolar dilution series in pet. of aluminium chloride hexahydrate and aluminium lactate, four times over a period of 8 months. Thirty-six of 84 (43%) serial dilution tests with aluminium chloride hexahydrate and 49 of 84 (58%) serial dilution tests with aluminium lactate gave negative results. The range of reactivity varied between a negative reaction to aluminium chloride hexahydrate at 10% and/or to aluminium lactate at 12%, and a positive reaction to aluminium chloride hexahydrate at 0.1% and/or to aluminium lactate at 0.12%. The highest individual difference in test reactivity noticed was 320-fold when the two most divergent minimal eliciting concentrations were compared. The patch test reactivity to aluminium varies over time. Aluminium-allergic individuals may have false-negative reactions. Therefore, retesting with aluminium should be considered when there is a strong suspicion of aluminium contact allergy. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Chameleon field and the late time acceleration of the Universe

Indian Academy of Sciences (India)

Chameleon field and the late time acceleration of the Universe. NARAYAN BANERJEE1,∗, SUDIPTA DAS2 and KOYEL GANGULY3. 1IISER-Kolkata, Mohanpur Campus, P.O. BCKV Main Office, District Nadia 741 252,. India. 2Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211 019, India.

Solvent effects in time-dependent self-consistent field methods. II. Variational formulations and analytical gradients

International Nuclear Information System (INIS)

Bjorgaard, J. A.; Velizhanin, K. A.; Tretiak, S.

2015-01-01

This study describes variational energy expressions and analytical excited state energy gradients for time-dependent self-consistent field methods with polarizable solvent effects. Linear response, vertical excitation, and state-specific solventmodels are examined. Enforcing a variational ground stateenergy expression in the state-specific model is found to reduce it to the vertical excitation model. Variational excited state energy expressions are then provided for the linear response and vertical excitation models and analytical gradients are formulated. Using semiempiricalmodel chemistry, the variational expressions are verified by numerical and analytical differentiation with respect to a static external electric field. Lastly, analytical gradients are further tested by performing microcanonical excited state molecular dynamics with p-nitroaniline

Temporal and spatial variations of travel-time residuals in central California for Novaya Zemlya events

International Nuclear Information System (INIS)

Robinson, R.; Iyer, H.M.

1976-01-01

Eight large nuclear explosions in Novaya Zemlya from October 1969 through November 1974 were used to monitor long-term variations in crustal seismic velocity near the San Andreas fault in central California. Relative P-wave travel-time residuals appear to be accurate to approximately +-0.1 sec. Of the over 100 stations used, none show clearly significant temporal variations in residual greater than this amount, corresponding to about a 4 percent change in velocity in the upper crust. Average relative residuals at individual stations show a large spatial variation of about 1.5 sec. These variations reflect both a complex crustal geology and changes in crustal thickness and provide a potentially powerful tool for studying crustal structure

SYSTEMATIC CENTER-TO-LIMB VARIATION IN MEASURED HELIOSEISMIC TRAVEL TIMES AND ITS EFFECT ON INFERENCES OF SOLAR INTERIOR MERIDIONAL FLOWS

Energy Technology Data Exchange (ETDEWEB)

Zhao Junwei; Nagashima, Kaori; Bogart, R. S.; Kosovichev, A. G. [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States); Duvall, T. L. Jr. [Solar Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2012-04-10

We report on a systematic center-to-limb variation in measured helioseismic travel times, which must be taken into account for an accurate determination of solar interior meridional flows. The systematic variation, found in time-distance helioseismology analysis using SDO/HMI and SDO/AIA observations, is different in both travel-time magnitude and variation trend for different observables. It is not clear what causes this systematic effect. Subtracting the longitude-dependent east-west travel times, obtained along the equatorial area, from the latitude-dependent north-south travel times, obtained along the central meridian area, gives remarkably similar results for different observables. We suggest this as an effective procedure for removing the systematic center-to-limb variation. The subsurface meridional flows obtained from inversion of the corrected travel times are approximately 10 m s{sup -1} slower than those obtained without removing the systematic effect. The detected center-to-limb variation may have important implications in the derivation of meridional flows in the deep interior and needs to be better understood.

SYSTEMATIC CENTER-TO-LIMB VARIATION IN MEASURED HELIOSEISMIC TRAVEL TIMES AND ITS EFFECT ON INFERENCES OF SOLAR INTERIOR MERIDIONAL FLOWS

International Nuclear Information System (INIS)

Zhao Junwei; Nagashima, Kaori; Bogart, R. S.; Kosovichev, A. G.; Duvall, T. L. Jr.

2012-01-01

We report on a systematic center-to-limb variation in measured helioseismic travel times, which must be taken into account for an accurate determination of solar interior meridional flows. The systematic variation, found in time-distance helioseismology analysis using SDO/HMI and SDO/AIA observations, is different in both travel-time magnitude and variation trend for different observables. It is not clear what causes this systematic effect. Subtracting the longitude-dependent east-west travel times, obtained along the equatorial area, from the latitude-dependent north-south travel times, obtained along the central meridian area, gives remarkably similar results for different observables. We suggest this as an effective procedure for removing the systematic center-to-limb variation. The subsurface meridional flows obtained from inversion of the corrected travel times are approximately 10 m s –1 slower than those obtained without removing the systematic effect. The detected center-to-limb variation may have important implications in the derivation of meridional flows in the deep interior and needs to be better understood.

Systematic Center-To-Limb Variation in Measured Helioseismic Travel Times and Its Effect on Inferences of Solar Interior Meridional Flows

Science.gov (United States)

Zhao, Junwei; Nagashima, Kaori; Bogart, R. S.; Kosovichev, Alexander; Duvall, T. L., Jr.

2012-01-01

We report on a systematic center-to-limb variation in measured helioseismic travel times, which must be taken into account for an accurate determination of solar interior meridional flows. The systematic variation, found in time-distance helioseismology analysis using SDO/HMI and SDO/AIA observations, is different in both travel-time magnitude and variation trend for different observables. It is not clear what causes this systematic effect. Subtracting the longitude-dependent east-west travel times, obtained along the equatorial area, from the latitude-dependent north-south travel times, obtained along the central meridian area, gives remarkably similar results for different observables. We suggest this as an effective procedure for removing the systematic center-to-limb variation. The subsurface meridional flows obtained from inversion of the corrected travel times are approximately 10 m s-1 slower than those obtained without removing the systematic effect. The detected center-to-limb variation may have important implications in the derivation of meridional flows in the deep interior and needs to be better understood.

Benchmarking the stochastic time-dependent variational approach for excitation dynamics in molecular aggregates

Energy Technology Data Exchange (ETDEWEB)

Chorošajev, Vladimir [Department of Theoretical Physics, Faculty of Physics, Vilnius University, Sauletekio 9-III, 10222 Vilnius (Lithuania); Gelzinis, Andrius; Valkunas, Leonas [Department of Theoretical Physics, Faculty of Physics, Vilnius University, Sauletekio 9-III, 10222 Vilnius (Lithuania); Department of Molecular Compound Physics, Center for Physical Sciences and Technology, Sauletekio 3, 10222 Vilnius (Lithuania); Abramavicius, Darius, E-mail: darius.abramavicius@ff.vu.lt [Department of Theoretical Physics, Faculty of Physics, Vilnius University, Sauletekio 9-III, 10222 Vilnius (Lithuania)

2016-12-20

Highlights: • The Davydov ansatze can be used for finite temperature simulations with an extension. • The accuracy is high if the system is strongly coupled to the environmental phonons. • The approach can simulate time-resolved fluorescence spectra. - Abstract: Time dependent variational approach is a convenient method to characterize the excitation dynamics in molecular aggregates for different strengths of system-bath interaction a, which does not require any additional perturbative schemes. Until recently, however, this method was only applicable in zero temperature case. It has become possible to extend this method for finite temperatures with the introduction of stochastic time dependent variational approach. Here we present a comparison between this approach and the exact hierarchical equations of motion approach for describing excitation dynamics in a broad range of temperatures. We calculate electronic population evolution, absorption and auxiliary time resolved fluorescence spectra in different regimes and find that the stochastic approach shows excellent agreement with the exact approach when the system-bath coupling is sufficiently large and temperatures are high. The differences between the two methods are larger, when temperatures are lower or the system-bath coupling is small.

Variation in computer time with geometry prescription in monte carlo code KENO-IV

International Nuclear Information System (INIS)

Gopalakrishnan, C.R.

1988-01-01

In most studies, the Monte Carlo criticality code KENO-IV has been compared with other Monte Carlo codes, but evaluation of its performance with different box descriptions has not been done so far. In Monte Carlo computations, any fractional savings of computing time is highly desirable. Variation in computation time with box description in KENO for two different fast reactor fuel subassemblies of FBTR and PFBR is studied. The K eff of an infinite array of fuel subassemblies is calculated by modelling the subassemblies in two different ways (i) multi-region, (ii) multi-box. In addition to these two cases, excess reactivity calculations of FBTR are also performed in two ways to study this effect in a complex geometry. It is observed that the K eff values calculated by multi-region and multi-box models agree very well. However the increase in computation time from the multi-box to the multi-region is considerable, while the difference in computer storage requirements for the two models is negligible. This variation in computing time arises from the way the neutron is tracked in the two cases. (author)

Dynamics of the sub-Ohmic spin-boson model: A time-dependent variational study

International Nuclear Information System (INIS)

Wu Ning; Duan Liwei; Zhao Yang; Li Xin

2013-01-01

The Dirac-Frenkel time-dependent variation is employed to probe the dynamics of the zero temperature sub-Ohmic spin-boson model with strong friction utilizing the Davydov D 1 ansatz. It is shown that initial conditions of the phonon bath have considerable influence on the dynamics. Counterintuitively, even in the very strong coupling regime, quantum coherence features still manage to survive under the polarized bath initial condition, while such features are absent under the factorized bath initial condition. In addition, a coherent-incoherent transition is found at a critical coupling strength α≈ 0.1 for s= 0.25 under the factorized bath initial condition. We quantify how faithfully our ansatz follows the Schrödinger equation, finding that the time-dependent variational approach is robust for strong dissipation and deep sub-Ohmic baths (s≪ 1).

Study of time variation of terrestrial gamma radiation due to depth distribution of soil moisture content

International Nuclear Information System (INIS)

Yoshioka, Katsuhiro

1994-01-01

An empirical equation was deduced from studies of time variations of terrestrial gamma exposure rate and soil moisture content with depth distribution in the surface layer. It was definitely suggested that the variation of terrestrial gamma exposure rate is most strongly influenced by the change of soil moisture content at 5 cm depth. The seasonal variation with a relative maximum in early autumn and a relative minimum in early spring was clearly obtained in the consequence of long time measurements of terrestrial gamma exposure rate and degree of soil dryness. The diurnal change and phase difference due to the effect of depth were also obtained in the dynamic characteristics of soil moisture content at 3 different depths. From the comparison between measured terrestrial gamma exposure rate and that evaluated from soil moisture content using the empirical equation, it was seen that seasonal variations of the both agreed fairly well as a whole. (author)

Co-gradient variation in growth rate and development time of a broadly distributed butterfly.

Directory of Open Access Journals (Sweden)

Madeleine Barton

Full Text Available Widespread species often show geographic variation in thermally-sensitive traits, providing insight into how species respond to shifts in temperature through time. Such patterns may arise from phenotypic plasticity, genetic adaptation, or their interaction. In some cases, the effects of genotype and temperature may act together to reduce, or to exacerbate, phenotypic variation in fitness-related traits across varying thermal environments. We find evidence for such interactions in life-history traits of Heteronympha merope, a butterfly distributed across a broad latitudinal gradient in south-eastern Australia. We show that body size in this butterfly is negatively related to developmental temperature in the laboratory, in accordance with the temperature-size rule, but not in the field, despite very strong temperature gradients. A common garden experiment on larval thermal responses, spanning the environmental extremes of H. merope's distribution, revealed that butterflies from low latitude (warmer climate populations have relatively fast intrinsic growth and development rates compared to those from cooler climates. These synergistic effects of genotype and temperature across the landscape (co-gradient variation are likely to accentuate phenotypic variation in these traits, and this interaction must be accounted for when predicting how H. merope will respond to temperature change through time. These results highlight the importance of understanding how variation in life-history traits may arise in response to environmental change. Without this knowledge, we may fail to detect whether organisms are tracking environmental change, and if they are, whether it is by plasticity, adaptation or both.

Temporal variation in bat-fruit interactions: Foraging strategies influence network structure over time

Science.gov (United States)

Zapata-Mesa, Natalya; Montoya-Bustamante, Sebastián; Murillo-García, Oscar E.

2017-11-01

Mutualistic interactions, such as seed dispersal, are important for the maintenance of structure and stability of tropical communities. However, there is a lack of information about spatial and temporal variation in plant-animal interaction networks. Thus, our goal was to assess the effect of bat's foraging strategies on temporal variation in the structure and robustness of bat-fruit networks in both a dry and a rain tropical forest. We evaluated monthly variation in bat-fruit networks by using seven structure metrics: network size, average path length, nestedness, modularity, complementary specialization, normalized degree and betweenness centrality. Seed dispersal networks showed variations in size, species composition and modularity; did not present nested structures and their complementary specialization was high compared to other studies. Both networks presented short path lengths, and a constantly high robustness, despite their monthly variations. Sedentary bat species were recorded during all the study periods and occupied more central positions than nomadic species. We conclude that foraging strategies are important structuring factors that affect the dynamic of networks by determining the functional roles of frugivorous bats over time; thus sedentary bats are more important than nomadic species for the maintenance of the network structure, and their conservation is a must.

On time variation of fundamental constants in superstring theories

International Nuclear Information System (INIS)

Maeda, K.I.

1988-01-01

Assuming the action from the string theory and taking into account the dynamical freedom of a dilaton and its coupling to matter fluid, the authors show that fundamental 'constants' in string theories are independent of the 'radius' of the internal space. Since the scalar related to the 'constants' is coupled to the 4-dimensional gravity and matter fluid in the same way as in the Jordan-Brans Dicke theory with ω = -1, it must be massive and can get a mass easily through some symmetry breaking mechanism (e.g. the SUSY breaking due to a gluino condensation). Consequently, time variation of fundamental constants is too small to be observed

The time to degree or dropout amongst full-time master's students at University of KwaZulu-Natal

Directory of Open Access Journals (Sweden)

Temesgen Zewotir

2015-09-01

Full Text Available Universities around the world are grappling with strategies to increase throughput and minimise dropout rates of postgraduate students. This study focuses on students at the University of KwaZulu-Natal and we attempt to estimate the time that it takes for these students to successfully complete or drop out from a master's programme. We used survival analysis to identify the factors which affect this. The results of this analysis showed that having some form of financial aid and/or being a student in the Faculties of Humanities or Management, all significantly shortened the length of time that it took to eventually drop out from a master's programme. For students who successfully completed a master's degree, having some form of financial aid, being of international origin and/or being registered in the Faculties of Health, Humanities, Law or Management, all helped to significantly shorten the length of time it took to successfully complete a master's programme. Students in the Faculty of Medicine, however, took longer to successfully complete their studies. Black Africans took less time to complete their master's degrees when compared with otherwise identical students from the other race groups.

Time series of low-degree geopotential coefficients from SLR data: estimation of Earth's figure axis and LOD variations

Science.gov (United States)

Luceri, V.; Sciarretta, C.; Bianco, G.

2012-12-01

The redistribution of the mass within the earth system induces changes in the Earth's gravity field. In particular, the second-degree geopotential coefficients reflect the behaviour of the Earth's inertia tensor of order 2, describing the main mass variations of our planet impacting the EOPs. Thanks to the long record of accurate and continuous laser ranging observations to Lageos and other geodetic satellites, SLR is the only current space technique capable to monitor the long time variability of the Earth's gravity field with adequate accuracy. Time series of low-degree geopotential coefficients are estimated with our analysis of SLR data (spanning more than 25 years) from several geodetic satellites in order to detect trends and periodic variations related to tidal effects and atmospheric/oceanic mass variations. This study is focused on the variations of the second-degree Stokes coefficients related to the Earth's principal figure axis and oblateness: C21, S21 and C20. On the other hand, surface mass load variations induce excitations in the EOPs that are proportional to the same second-degree coefficients. The time series of direct estimates of low degree geopotential and those derived from the EOP excitation functions are compared and presented together with their time and frequency analysis.

Sonority as variation: A study about the conceptualization of physical notions in university students

International Nuclear Information System (INIS)

Escudero, Consuelo; Jaime, Eduardo A

2007-01-01

Results of researches over conceptions and specific competencies of university students as regards acoustic waves and their conceptualization are put forward in this paper. The starting point is a theoretical scheme previously done that allows the linking and interconnection of theorical contributions related with the cognitive psychology, the developmental psychology, problems solving, the linguistic and symbolical representation of concepts and their relation with the didactics. The corpus is made up mainly by answers to written works which have allowed analyzing implicit conceptions of students, especially those ignored or misunderstood by them. This is a qualitative research, in which data are grouped in categories that are not provided before the theoretical framework. Conclusions show the potentiality of the theoretical framework to interpret processes of meaning building of the level of sonority as variation, and for the design and improvement of instructional proposals tending to achieve a critical meaningful learning

Sonority as variation: A study about the conceptualization of physical notions in university students

Energy Technology Data Exchange (ETDEWEB)

Escudero, Consuelo; Jaime, Eduardo A [Departamento de Fisica, Facultad de Ingenieria - UNSJ (Argentina); Departamento de BiologIa, Facultad de Ciencias Exactas, Fisicas y Naturales - UNSJ (Argentina)

2007-11-15

Results of researches over conceptions and specific competencies of university students as regards acoustic waves and their conceptualization are put forward in this paper. The starting point is a theoretical scheme previously done that allows the linking and interconnection of theorical contributions related with the cognitive psychology, the developmental psychology, problems solving, the linguistic and symbolical representation of concepts and their relation with the didactics. The corpus is made up mainly by answers to written works which have allowed analyzing implicit conceptions of students, especially those ignored or misunderstood by them. This is a qualitative research, in which data are grouped in categories that are not provided before the theoretical framework. Conclusions show the potentiality of the theoretical framework to interpret processes of meaning building of the level of sonority as variation, and for the design and improvement of instructional proposals tending to achieve a critical meaningful learning.

Variation in Patients' Travel Times among Imaging Examination Types at a Large Academic Health System.

Science.gov (United States)

Rosenkrantz, Andrew B; Liang, Yu; Duszak, Richard; Recht, Michael P

2017-08-01

Patients' willingness to travel farther distances for certain imaging services may reflect their perceptions of the degree of differentiation of such services. We compare patients' travel times for a range of imaging examinations performed across a large academic health system. We searched the NYU Langone Medical Center Enterprise Data Warehouse to identify 442,990 adult outpatient imaging examinations performed over a recent 3.5-year period. Geocoding software was used to estimate typical driving times from patients' residences to imaging facilities. Variation in travel times was assessed among examination types. The mean expected travel time was 29.2 ± 20.6 minutes, but this varied significantly (p travel times were shortest for ultrasound (26.8 ± 18.9) and longest for positron emission tomography-computed tomography (31.9 ± 21.5). For magnetic resonance imaging, travel times were shortest for musculoskeletal extremity (26.4 ± 19.2) and spine (28.6 ± 21.0) examinations and longest for prostate (35.9 ± 25.6) and breast (32.4 ± 22.3) examinations. For computed tomography, travel times were shortest for a range of screening examinations [colonography (25.5 ± 20.8), coronary artery calcium scoring (26.1 ± 19.2), and lung cancer screening (26.4 ± 14.9)] and longest for angiography (32.0 ± 22.6). For ultrasound, travel times were shortest for aortic aneurysm screening (22.3 ± 18.4) and longest for breast (30.1 ± 19.2) examinations. Overall, men (29.9 ± 21.6) had longer (p travel times than women (27.8 ± 20.3); this difference persisted for each modality individually (p ≤ 0.006). Patients' willingness to travel longer times for certain imaging examination types (particularly breast and prostate imaging) supports the role of specialized services in combating potential commoditization of imaging services. Disparities in travel times by gender warrant further investigation. Copyright �

Age-related differences in the neural correlates of trial-to-trial variations of reaction time

Directory of Open Access Journals (Sweden)

Nancy E. Adleman

2016-06-01

Full Text Available Intra-subject variation in reaction time (ISVRT is a developmentally-important phenomenon that decreases from childhood through young adulthood in parallel with the development of executive functions and networks. Prior work has shown a significant association between trial-by-trial variations in reaction time (RT and trial-by-trial variations in brain activity as measured by the blood-oxygenated level-dependent (BOLD response in functional magnetic resonance imaging (fMRI studies. It remains unclear, however, whether such “RT-BOLD” relationships vary with age. Here, we determined whether such trial-by-trial relationships vary with age in a cross-sectional design. We observed an association between age and RT-BOLD relationships in 11 clusters located in visual/occipital regions, frontal and parietal association cortex, precentral/postcentral gyrus, and thalamus. Some of these relationships were negative, reflecting increased BOLD associated with decreased RT, manifesting around the time of stimulus presentation and positive several seconds later. Critically for present purposes, all RT-BOLD relationships increased with age. Thus, RT-BOLD relationships may reflect robust, measurable changes in the brain-behavior relationship across development.

Is there a time trend in medical practice variations?: a review of the literature and an critical analysis of theoretical approaches.

NARCIS (Netherlands)

Groenewegen, P.P.; Westert, G.P.

2004-01-01

The aim of this study was to review the research evidence for a decreasing time trend in medical practice variation and to contribute to our theoretical understanding of trends in medical practice variations. We searched Pubmed for articles reporting on time trends in medical practice variations.

Effects of solvent evaporation time on immediate adhesive properties of universal adhesives to dentin.

Science.gov (United States)

Luque-Martinez, Issis V; Perdigão, Jorge; Muñoz, Miguel A; Sezinando, Ana; Reis, Alessandra; Loguercio, Alessandro D

2014-10-01

To evaluate the microtensile bond strengths (μTBS) and nanoleakage (NL) of three universal or multi-mode adhesives, applied with increasing solvent evaporation times. One-hundred and forty caries-free extracted third molars were divided into 20 groups for bond strength testing, according to three factors: (1) Adhesive - All-Bond Universal (ABU, Bisco, Inc.), Prime&Bond Elect (PBE, Dentsply), and Scotchbond Universal Adhesive (SBU, 3M ESPE); (2) Bonding strategy - self-etch (SE) or etch-and-rinse (ER); and (3) Adhesive solvent evaporation time - 5s, 15s, and 25s. Two extra groups were prepared with ABU because the respective manufacturer recommends a solvent evaporation time of 10s. After restorations were constructed, specimens were stored in water (37°C/24h). Resin-dentin beams (0.8mm(2)) were tested at 0.5mm/min (μTBS). For NL, forty extracted molars were randomly assigned to each of the 20 groups. Dentin disks were restored, immersed in ammoniacal silver nitrate, sectioned and processed for evaluation under a FESEM in backscattered mode. Data from μTBS were analyzed using two-way ANOVA (adhesive vs. drying time) for each strategy, and Tukey's test (α=0.05). NL data were computed with non-parametric tests (Kruskal-Wallis and Mann-Whitney tests, α=0.05). Increasing solvent evaporation time from 5s to 25s resulted in statistically higher mean μTBS for all adhesives when used in ER mode. Regarding NL, ER resulted in greater NL than SE for each of the evaporation times regardless of the adhesive used. A solvent evaporation time of 25s resulted in the lowest NL for SBU-ER. Residual water and/or solvent may compromise the performance of universal adhesives, which may be improved with extended evaporation times. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Varying couplings in the early universe: Correlated variations of α and G

International Nuclear Information System (INIS)

Martins, C. J. A. P.; Menegoni, Eloisa; Galli, Silvia; Mangano, Gianpiero; Melchiorri, Alessandro

2010-01-01

The cosmic microwave background anisotropies provide a unique opportunity to constrain simultaneous variations of the fine-structure constant α and Newton's gravitational constant G. Those correlated variations are possible in a wide class of theoretical models. In this brief paper we show that the current data, assuming that particle masses are constant, give no clear indication for such variations, but already prefer that any relative variations in α should be of the same sign of those of G for variations of ∼1%. We also show that a cosmic complementarity is present with big bang nucleosynthesis and that a combination of current CMB and big bang nucleosynthesis data strongly constraints simultaneous variations in α and G. We finally discuss the future bounds achievable by the Planck satellite mission.

SU-E-T-326: The Oxygen Saturation (SO2) and Breath-Holding Time Variation Applied Active Breathing Control (ABC)

Energy Technology Data Exchange (ETDEWEB)

Gong, G; Yin, Y [Shandong Cancer Hospital, Jinan, Shandong (China)

2014-06-01

Purpose: To study the oxygen saturation (SO2) and breath-holding time variation applied active breathing control (ABC) in radiotherapy of tumor. Methods: 24 volunteers were involved in our trials, and they all did breath-holding motion assisted by ELEKTA Active Breathing Coordinator 2.0 for 10 times respectively. And the patient monitor was used to observe the oxygen saturation (SO2) variation. The variation of SO2, and length of breath-holding time and the time for recovering to the initial value of SO2 were recorded and analyzed. Results: (1) The volunteers were divided into two groups according to the SO2 variation in breath-holding: A group, 14 cases whose SO2 reduction were more than 2% (initial value was 97% to 99%, while termination value was 91% to 96%); B group, 10 cases were less than 2% in breath-holding without inhaling oxygen. (2) The interfraction breath holding time varied from 8 to 20s for A group compared to the first breath-holding time, and for B group varied from 4 to 14s. (3) The breathing holding time of B group prolonged mean 8s, compared to A group. (4) The time for restoring to the initial value of SO2 was from 10s to 30s. And the breath-holding time shortened obviously for patients whose SO2 did not recover to normal. Conclusion: It is very obvious that the SO2 reduction in breath-holding associated with ABC for partial people. It is necessary to check the SO2 variation in breath training, and enough time should be given to recover SO2.

Analyzing Seasonal Variations in Suicide With Fourier Poisson Time-Series Regression: A Registry-Based Study From Norway, 1969-2007.

Science.gov (United States)

Bramness, Jørgen G; Walby, Fredrik A; Morken, Gunnar; Røislien, Jo

2015-08-01

Seasonal variation in the number of suicides has long been acknowledged. It has been suggested that this seasonality has declined in recent years, but studies have generally used statistical methods incapable of confirming this. We examined all suicides occurring in Norway during 1969-2007 (more than 20,000 suicides in total) to establish whether seasonality decreased over time. Fitting of additive Fourier Poisson time-series regression models allowed for formal testing of a possible linear decrease in seasonality, or a reduction at a specific point in time, while adjusting for a possible smooth nonlinear long-term change without having to categorize time into discrete yearly units. The models were compared using Akaike's Information Criterion and analysis of variance. A model with a seasonal pattern was significantly superior to a model without one. There was a reduction in seasonality during the period. Both the model assuming a linear decrease in seasonality and the model assuming a change at a specific point in time were both superior to a model assuming constant seasonality, thus confirming by formal statistical testing that the magnitude of the seasonality in suicides has diminished. The additive Fourier Poisson time-series regression model would also be useful for studying other temporal phenomena with seasonal components. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Modeling of electron time variations in the radiation belts

International Nuclear Information System (INIS)

Chan, K.W.; Teague, M.J.; Schofield, N.J.; Vette, J.I.

1979-01-01

A review of the temporal variation in the trapped electron population of the inner and outer radiation zones is presented. Techniques presently used for modeling these zones are discussed and their deficiencies identified. An intermediate region is indicated between the zones in which the present modeling techniques are inadequate due to the magnitude and frequency of magnetic storms. Future trends are examined, and it is suggested that modeling of individual magnetic storms may be required in certain L bands. An analysis of seven magnetic storms is presented, establishing the independence of the depletion time of the storm flux and the storm magnitude. Provisional correlation between the storm magnitude and the Dst index is demonstrated

Temperature and time variations during osteotomies performed with different piezosurgical devices: an in vitro study.

Science.gov (United States)

Delgado-Ruiz, R A; Sacks, D; Palermo, A; Calvo-Guirado, J L; Perez-Albacete, C; Romanos, G E

2016-09-01

The aim of this experimental in vitro study was to evaluate the effects of the piezoelectric device in temperature and time variations in standardized osteotomies performed with similar tip inserts in bovine bone blocks. Two different piezosurgical devices were used the OE-F15(®) (Osada Inc., Los Angeles, California, USA) and the Surgybone(®) (Silfradent Inc., Sofia, Forli Cesena, Italy). Serrated inserts with similar geometry were coupled with each device (ST94 insert/test A and P0700 insert/test B). Osteotomies 10 mm long and 3 mm deep were performed in bone blocks resembling type II (dense) and type IV (soft) bone densities with and without irrigation. Thermal changes and time variations were recorded. The effects of bone density, irrigation, and device on temperature changes and time necessary to accomplish the osteotomies were analyzed. Thermal analysis showed significant higher temperatures during piezosurgery osteotomies in hard bone without irrigation (P  0.05). Time analysis showed that the mean time values necessary to perform osteotomies were shorter in soft bone than in dense bone (P piezosurgery osteotomies in dense bone without irrigation; the time to perform the osteotomy with piezosurgery is shorter in soft bone compared to hard bone; and the piezosurgical device have a minimal influence in the temperature and time variations when a similar tip design is used during piezosurgery osteotomies. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A Discrete-Time Model for Daily S&P500 Returns and Realized Variations: Jumps and Leverage Effects

DEFF Research Database (Denmark)

Bollerslev, Tim; Kretschmer, Uta; Pigorsch, Christian

We develop an empirically highly accurate discrete-time daily stochastic volatility model that explicitly distinguishes between the jump and continuoustime components of price movements using nonparametric realized variation and Bipower variation measures constructed from high-frequency intraday...... dependencies inherent in the high-frequency intraday data....

Removing tidal-period variations from time-series data using low-pass digital filters

Science.gov (United States)

Walters, Roy A.; Heston, Cynthia

1982-01-01

Several low-pass, digital filters are examined for their ability to remove tidal Period Variations from a time-series of water surface elevation for San Francisco Bay. The most efficient filter is the one which is applied to the Fourier coefficients of the transformed data, and the filtered data recovered through an inverse transform. The ability of the filters to remove the tidal components increased in the following order: 1) cosine-Lanczos filter, 2) cosine-Lanczos squared filter; 3) Godin filter; and 4) a transform fitter. The Godin fitter is not sufficiently sharp to prevent severe attenuation of 2–3 day variations in surface elevation resulting from weather events.

TIME VARIATION OF AV AND RV FOR TYPE Ia SUPERNOVAE BEHIND INTERSTELLAR DUST

Science.gov (United States)

Huang, Xiaosheng; Biederman, M.; Herger, B.; Aldering, G. S.

2014-01-01

TIME VARIATION OF AV AND RV FOR TYPE Ia SUPERNOVAE BEHIND NON-UNIFORM INTERSTELLAR DUST ABSTRACT We investigate the time variation of the visual extinction, AV, and the total-to-selective extinction ratio, RV, resulting from interstellar dust in front of an expanding photospheric disk of a type Ia supernova (SN Ia). We simulate interstellar dust clouds according to a power law power spectrum and produce extinction maps that either follow a pseudo-Gaussian distribution or a lognormal distribution. The RV maps are produced through a correlation between AV and RV. With maps of AV and RV generated in each case (pseudo-Gaussian and lognormal), we then compute the effective AV and RV for a SN as its photospheric disk expands behind the dust screen. We find for a small percentage of SNe the AV and RV values can vary by a large factor from day to day in the first 40 days after explosion.

The Expanding Universe: Time, Space and Spirit--Keys to Scientific Literacy Series.

Science.gov (United States)

Stonebarger, Bill

Nearly every culture has made important discoveries about the universe. Most cultures have searched for a better understanding of the cosmos and how the earth and human life relate. The discussion in this booklet considers time, space, and spirit. Time refers to a sense of history; space refers to geography; and spirit refers to life and thought.…

Fast solution of Cahn–Hilliard variational inequalities using implicit time discretization and finite elements

KAUST Repository

Bosch, Jessica; Stoll, Martin; Benner, Peter

2014-01-01

We consider the efficient solution of the Cahn-Hilliard variational inequality using an implicit time discretization, which is formulated as an optimal control problem with pointwise constraints on the control. By applying a semi-smooth Newton

Time-variations of the regional evapotranspiration rate from GRACE satellite gravimetry

OpenAIRE

Ramillien , Guillaume; Frappart , Frédéric; Güntner , Andreas; Ngo-Duc , Thanh; Cazenave , Anny; Laval , Katia

2006-01-01

International audience; Since its launch in March 2002, the GRACE mission is measuring the global time variations of the Earth's gravity field with a current resolution of ~500 km. Especially over the continents, these measurements represent the integrated land water mass including surface waters (lakes, wetlands and rivers), soil moisture, groundwater and snow cover. In this study, we use the GRACE land water solutions computed by Ramillien et al. (2005a) through an iterative inversion of mo...

Empirical model of subdaily variations in the Earth rotation from GPS and its stability

Science.gov (United States)

Panafidina, N.; Kurdubov, S.; Rothacher, M.

2012-12-01

The model recommended by the IERS for these variations at diurnal and semidiurnal periods has been computed from an ocean tide model and comprises 71 terms in polar motion and Universal Time. In the present study we compute an empirical model of variations in the Earth rotation on tidal frequencies from homogeneously re-processed GPS-observations over 1994-2007 available as free daily normal equations. We discuss the reliability of the obtained amplitudes of the ERP variations and compare results from GPS and VLBI data to identify technique-specific problems and instabilities of the empirical tidal models.

Variation of CRE with exponents of time and number of fractions

International Nuclear Information System (INIS)

Supe, S.J.; Rao, S.M.; Sawant, S.G.; Bisht, J.S.

1976-01-01

The concept of NSD has been modified into TDF's by Orton and Ellis and CRE's by Kirk et al. It was aimed to study the variability of these new concepts on the exponents of time and number of fractions. It was found that TDF has larger variation with the exponents compared to that of CRE. The use of CRE and NSD for solving the treatment scheduling problems or for intercomparison of various regimes has been simplified by providing readymade estimation of CRE for various doses/fraction with increasing number of fractions. As there is increasing evidence for the change of exponents J and H, nomograms are presented to determine the CRE for various values of J and H. The variation of decay correction factors with the exponent H is also evaluated and is presented. This will help various radiotherapists to use CRE and the decay correction factors consistent with their clinical findings. (orig.) [de

Variations of extreme rainfall in space and time

DEFF Research Database (Denmark)

Gregersen, Ida Bülow; Madsen, H.; Rosbjerg, Dan

2012-01-01

variation, whereas annual variations are related to changes in the average Danish summer precipitation, the average Danish summer temperature and the East Atlantic pattern. The spatio-temporal Poisson regression model was found to be a helpful tool when comparing the internal importance of these variables......In the ongoing climate change discussion, methods for identification of variability governed by climate change are important tools. The magnitude of variables that can describe this variability should be compared with magnitudes of variables describing variability in a stationary setting....... This study focuses on variations of extreme rainfall events, observed at 70 different locations in Denmark over a period of 31 years. The aim is to identify and compare variables, both spatially and temporally, which can explain different parts of the variability in this data set. Assuming that the number...

Time dependency of local cerebral blood flow measurements caused by regional variations in tissue transit time

International Nuclear Information System (INIS)

Lear, J.L.; Kasliwal, R.; Feyerabend, A.

1990-01-01

Calculated values of local cerebral blood flow (LCBF) using the diffusible tracer model are assumed to be independent of time as long as experiments are brief enough to prevent tissue saturation. This paper investigates the effects of CTT variation on LCBF measurements. Using double-label quantitative digital autoradiography, we compared iodoantipyrine (IAP)-based LCBF measurements obtained with tracer infusions of different lengths of time. Lightly anesthetized rats were given simultaneous ramp infusions of C-14 IAP (45 seconds) and I-123 IAP (15 seconds) and immediately sacrificed. Two autoradiograms of each brain section, one representing I-123 and the other representing C-14, were produced, digitized, and converted into images of LCBF based on the 15- and 45-second infusion periods. The LCBF image pairs were compared on a pixel-by-pixel basis

Measurement of time series variation of thermal diffusivity of magnetic fluid under magnetic field by forced Rayleigh scattering method

Energy Technology Data Exchange (ETDEWEB)

Motozawa, Masaaki, E-mail: motozawa.masaaki@shizuoka.ac.jp [Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu-shi, Shizuoka 432-8561 (Japan); Muraoka, Takashi [Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu-shi, Shizuoka 432-8561 (Japan); Motosuke, Masahiro, E-mail: mot@rs.tus.ac.jp [Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585 (Japan); Fukuta, Mitsuhiro, E-mail: fukuta.mitsuhiro@shizuoka.ac.jp [Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu-shi, Shizuoka 432-8561 (Japan)

2017-04-15

It can be expected that the thermal diffusivity of a magnetic fluid varies from time to time after applying a magnetic field because of the growth of the inner structure of a magnetic fluid such as chain-like clusters. In this study, time series variation of the thermal diffusivity of a magnetic fluid caused by applying a magnetic field was investigated experimentally. For the measurement of time series variation of thermal diffusivity, we attempted to apply the forced Rayleigh scattering method (FRSM), which has high temporal and high spatial resolution. We set up an optical system for the FRSM and measured the thermal diffusivity. A magnetic field was applied to a magnetic fluid in parallel and perpendicular to the heat flux direction, and the magnetic field intensity was 70 mT. The FRSM was successfully applied to measurement of the time series variation of the magnetic fluid from applying a magnetic field. The results show that a characteristic configuration in the time series variation of the thermal diffusivity of magnetic fluid was obtained in the case of applying a magnetic field parallel to the heat flux direction. In contrast, in the case of applying a magnetic field perpendicular to the heat flux, the thermal diffusivity of the magnetic fluid hardly changed during measurement. - Highlights: • Thermal diffusivity was measured by forced Rayleigh scattering method (FRSM). • FRSM has high temporal and high spatial resolutions for measurement. • We attempted to apply FRSM to magnetic fluid (MF). • Time series variation of thermal diffusivity of MF was successfully measured by FRSM. • Anisotropic thermal diffusivity of magnetic fluid was also successfully confirmed.

Late time acceleration of the universe in f(R) gravity model

International Nuclear Information System (INIS)

Mukherjee, Ankan

2014-01-01

In this work, a new way to look at the nature of late time dynamics of the universe for f(R) gravity models using the contracted Bianchi Identity has been proposed. As the Einstein field equations contain derivatives of the curvature scalar R, the contracted Bianchi identity yields a second order nonlinear differential equation in H, the Hubble parameter. This equation is studied for two particular forms of f(R), and the late time behaviour of the model is discussed. (author)

Stress and Time Management Settings in University of Maroua, Cameroon

Directory of Open Access Journals (Sweden)

Joseph BESONG BESONG

2015-06-01

Full Text Available The aim of this paper is to examine stress and time in educational management in Maroua University. These two phenomena are profound in educational issues in Cameroon due to the complex administration or management. Education comprised of diversity of activities ranging from administration, discipline, teaching, evaluation and learning. Each of these activities requires time schedule to avoid stress in the face of pressure. Administration requires planning, organizing, controlling, commanding, coordinating, reporting and budgeting. Each of these managing variables requires time, just as discipline, teaching, evaluation and learning should need. The situation may be affected by higher authority interference and cause a rush thus affecting every schedule in the system on this note, it is necessary that every administrator on management cadre should develop a list of activities such as admissions, examinations, sports, vacations and other ceremonies which requires his attention on daily, weekly, or monthly bases and there after allocate in a tentative fashion the most appropriate times for dealing with such activities. Some profile recommendations are: strict adhering to schedules to avoid overlapping or prolongation to other programs; the schedules should be pasted or placed at a convenient point in the office for reference to avoid forgetfulness: as an administrator, time should be allocated for meeting or consulting with visitors and subordinates; he should delegate functions to his accredited subordinates to crave chance or time for essential duty; he should review the school or organization programs on daily, weekly or monthly bases the degree to which his administration goals have been attained and he (i.e. administrator should crave time for rest i.e. holidays, relaxation and various forms of physical exercises to revitalizes the body for subsequent activities. The paper recommends planning which is vital in management to avoid time waste

The universe in your hand a journey through space, time and beyond

CERN Document Server

Galfard, Christophe

2015-01-01

Imagine if The Hitchhiker's Guide to the Galaxy were a real, practical book about the mysteries of the universe...The Universe In Your Hand takes us on a wonder-filled journey to the surface of our dying Sun, shrinks us to the size of an atom and puts us in the deathly grip of distant Black Holes. Along the way you might come to understand, really understand, the mind-bending science that underpins modern life, from Quantum Mechanics to Einstein's theory of General Relativity. Through brilliant storytelling and humour rather than graphs and equations, internationally renowned astrophysicist Christophe Galfard has written an instant classic that brings the astonishing beauty of the universe to life - and takes us deep into questions about the beginning of time and the future of humanity.

Part-Time Work and Advancement: A Study of Female Professional Staff in Australian Universities

Science.gov (United States)

Bailey, Janis; Troup, Carolyn; Strachan, Glenda

2017-01-01

One focus of gender equity policies in universities has been the creation of "retention" part-time work for professional staff, which allows employees to move between full-time and part-time hours at their request. This paper examines whether such "good" part-time jobs can contribute to or at least not impede women's career…

Frequency variations of gravity waves interacting with a time-varying tide

Energy Technology Data Exchange (ETDEWEB)

Huang, C.M.; Zhang, S.D.; Yi, F.; Huang, K.M.; Gan, Q.; Gong, Y. [Wuhan Univ., Hubei (China). School of Electronic Information; Ministry of Education, Wuhan, Hubei (China). Key Lab. of Geospace Environment and Geodesy; State Observatory for Atmospheric Remote Sensing, Wuhan, Hubei (China); Zhang, Y.H. [Nanjing Univ. of Information Science and Technology (China). College of Hydrometeorolgy

2013-11-01

Using a nonlinear, 2-D time-dependent numerical model, we simulate the propagation of gravity waves (GWs) in a time-varying tide. Our simulations show that when aGW packet propagates in a time-varying tidal-wind environment, not only its intrinsic frequency but also its ground-based frequency would change significantly. The tidal horizontal-wind acceleration dominates the GW frequency variation. Positive (negative) accelerations induce frequency increases (decreases) with time. More interestingly, tidal-wind acceleration near the critical layers always causes the GW frequency to increase, which may partially explain the observations that high-frequency GW components are more dominant in the middle and upper atmosphere than in the lower atmosphere. The combination of the increased ground-based frequency of propagating GWs in a time-varying tidal-wind field and the transient nature of the critical layer induced by a time-varying tidal zonal wind creates favorable conditions for GWs to penetrate their originally expected critical layers. Consequently, GWs have an impact on the background atmosphere at much higher altitudes than expected, which indicates that the dynamical effects of tidal-GW interactions are more complicated than usually taken into account by GW parameterizations in global models.

Beach morphological variations over micro-time scales

Digital Repository Service at National Institute of Oceanography (India)

Murty, C.S.; Veerayya, M.; Sastry, J.S.; Varadachari, V.V.R.

formation, variations in the profiles show anomalous behaviour. The differences in grain-size distribution of the sediments of these 2 beaches are attributed to the available wave energies at these 2 locations...

Universal SaaS platform of internet of things for real-time monitoring

Science.gov (United States)

Liu, Tongke; Wu, Gang

2018-04-01

Real-time monitoring service, as a member of the IoT (Internet of Things) service, has a wide range application scenario. To support rapid construction and deployment of applications and avoid repetitive development works in these processes, this paper designs and develops a universal SaaS platform of IoT for real-time monitoring. Evaluation shows that this platform can provide SaaS service to multiple tenants and achieve high real-time performance under the situation of large amount of device access.

Boundedness and almost Periodicity in Time of Solutions of Evolutionary Variational Inequalities

Science.gov (United States)

Pankov, A. A.

1983-04-01

In this paper existence theorems are obtained for the solutions of abstract parabolic variational inequalities, which are bounded with respect to time (in the Stepanov and L^\\infty norms). The regularity and almost periodicity properties of such solutions are studied. Theorems are also established concerning their solvability in spaces of Besicovitch almost periodic functions. The majority of the results are obtained without any compactness assumptions. Bibliography: 30 titles.

Geographic variations in avoidable hospitalizations in the elderly, in a health system with universal coverage

Directory of Open Access Journals (Sweden)

Alberquilla Angel

2008-02-01

Full Text Available Abstract Background The study of Hospitalizations for ambulatory care sensitive conditions (ACSH has been proposed as an indirect measure of access to and receipt of care by older persons at the entryway to the Spanish public health system. The aim of this work is to identify the rates of ACSH in persons 65 years or older living in different small-areas of the Community of Madrid (CM and to detect possible differences in ACSH. Methods Cross-sectional, ecologic study, which covered all 34 health districts of the CM. The study population consisted of all individuals aged 65 years or older residing in the CM between 2001 and 2003, inclusive. Using hospital discharge data, avoidable ACSH were selected from the list of conditions validated for Spain. Age- and sex-adjusted ACSH rates were calculated for the population of each health district and the statistics describing the data variability. Point graphs and maps were designed to represent the ACSH rates in the different health districts. Results Of all the hospitalizations, 16.5% (64,409 were ACSH. Globally, the rate was higher among men: 33.15 per 1,000 populations vs. 22.10 in women and these differences were statistically significant (p Conclusion A significant variation is demonstrated in "preventable" hospitalizations between the different districts. In all the districts the men present rates significantly higher than women. Important variations in the access are observed the Primary Attention in spite of existing a universal sanitary cover.

Universal Earthquake-Occurrence Jumps, Correlations with Time, and Anomalous Diffusion

International Nuclear Information System (INIS)

Corral, Alvaro

2006-01-01

Spatiotemporal properties of seismicity are investigated for a worldwide (WW) catalog and for southern California in the stationary case (SC), showing a nearly universal scaling behavior. Distributions of distances between consecutive earthquakes (jumps) are magnitude independent and show two power-law regimes, separated by jump values about 200 (WW) and 15 km (SC). Distributions of waiting times conditioned to the value of jumps show that both variables are correlated, in general, but turn out to be independent when only short or long jumps are considered. Finally, diffusion profiles are found to be independent on the magnitude, contrary to what the waiting-time distributions suggest

Case studies of the storm time variation of the polar cusp

International Nuclear Information System (INIS)

Meng, C.

1983-01-01

The latitudinal variations of the polar cusp region were examined during three intense geomagnetic storms. The variations were compared with the intensity of storm time ring current inferred from the Dst index, with the magnitude of the north-south component B/sub z/ of the interplanetary magnetic field and with substorm activity. The common feature is that the rapid equatorward shift occurred during the increase of the ring current growth and during the southward turning of the interplanetary magnetic field orientation. The equatorwardmost latitude of the cusp was reached before the peak of the ring current intensity, by a few to several hours, coinciding with the occurrence of the largest magnitude of the southward interplanetary magnetic field component. However, details of the polar cusp latitudinal movement differ from storm to storm. During the three storms studied, the poleward recovery commenced at the peak magnitude of the negative IMF B/sub z/ component, but the recovery proceeded without a clear relation to variations of the interplanetary B/sub z/ component, to the ring current intensity, or to the substorm activity. The lowest cusp latitude observed was at approx.61.7 0 , and the magnitude of this shift seems to be related to the magnitudes of -B/sub z/. It is further observed that the approximate rates of the cusp macroscopic equatorward and poleward movements are about 3 0 and 1.5 0 per hour, respectively

Variations with time and age of the excess cancer risk among A-bomb survivors

International Nuclear Information System (INIS)

Pierce, D.A.; Vaeth, M.; Preston, D.L.

1990-08-01

This report has two aims: 1) to describe and analyze the age/time patterns of excess cancer risk in the atomic bomb survivor cohort followed up by RERF, and 2) to describe statistical methods which are used in RERF's analyses of data on mortality and morbidity in the cohort. In contrast to previous analyses of the cohort cancer mortality data, substantial use is made of Japanese national cancer rates for the purpose of investigation of the age/time variations in excess risk. This analysis considers mortality from all cancers except leukemia as a group. Primary attention is given to description in terms of the age-specific excess relative risk, but the importance of appropriate descriptions of the absolute excess risk is also emphasized. When models for the excess risk allow variation with age and time, both constant relative and absolute excess risk models provide very similar fits to the data. Previous reports have indicated that for a given age-at-exposure and sex, the excess age-specific relative risk is remarkably constant throughout the current follow-up period. Statistical analysis here indicates that for those less than about 35 years of age at exposure there is no departure from this pattern, beyond ordinary sampling variation. For those over about 35 years of age-at-exposure, there is modest evidence of an increasing trend in the excess relative risk, which could be plausibly attributed to effects related to minimal latent period. Some brief consideration is given to modeling the absolute excess risk as the product of an age-at-exposure and time-since-exposure effect. Interpretation of these results, particularly in regard to projections beyond the current follow-up, is discussed. (author)

Nonlinear Variation of Parameters Formula for Impulsive Differential Equations with Initial Time Difference and Application

Directory of Open Access Journals (Sweden)

Peiguang Wang

2014-01-01

Full Text Available This paper establishes variation of parameters formula for impulsive differential equations with initial time difference. As an application, one of the results is used to investigate stability properties of solutions.

Short-time variations of the ground water level

International Nuclear Information System (INIS)

Nilsson, Lars Y.

1977-09-01

Investigations have demonstrated that the ground water level of aquifers in the Swedish bedrock shows shorttime variations without changing their water content. The ground water level is among other things affected by regular tidal movements occuring in the ''solid'' crust of the earth variations in the atmospheric pressure strong earthquakes occuring in different parts of the world These effects proves that the system of fissures in the bedrock are not stable and that the ground water flow is influenced by both water- and airfilled fissures

Study on the Variation of Groundwater Level under Time-varying Recharge

Science.gov (United States)

Wu, Ming-Chang; Hsieh, Ping-Cheng

2017-04-01

The slopes of the suburbs come to important areas by focusing on the work of soil and water conservation in recent years. The water table inside the aquifer is affected by rainfall, geology and topography, which will result in the change of groundwater discharge and water level. Currently, the way to obtain water table information is to set up the observation wells; however, owing to that the cost of equipment and the wells excavated is too expensive, we develop a mathematical model instead, which might help us to simulate the groundwater level variation. In this study, we will discuss the groundwater level change in a sloping unconfined aquifer with impermeable bottom under time-varying rainfall events. Referring to Child (1971), we employ the Boussinesq equation as the governing equation, and apply the General Integral Transforms Method (GITM) to analyzing the groundwater level after linearizing the Boussinesq equation. After comparing the solution with Verhoest & Troch (2000) and Bansal & Das (2010), we get satisfactory results. To sum up, we have presented an alternative approach to solve the linearized Boussinesq equation for the response of groundwater level in a sloping unconfined aquifer. The present analytical results combine the effect of bottom slope and the time-varying recharge pattern on the water table fluctuations. Owing to the limitation and difficulty of measuring the groundwater level directly, we develop such a mathematical model that we can predict or simulate the variation of groundwater level affected by any rainfall events in advance.

Period variations in pulsating X-ray sources. I. Accretion flow parameters and neutron star structure from timing observations

International Nuclear Information System (INIS)

Lamb, F.K.; Pines, D.; Shaham, J.

1978-01-01

We show that valuable information about both accretion flows and neutron star structure can be obtained from X-ray timing observations of period variations in pulsating sources. Such variations can result from variations in the accretion flow, or from internal torque variations, associated with oscillations of the fluid core or the unpinning of vortices in the inner crust. We develop a statistical description of torque variations in terms of noise processes, indicate how the applicability of such a description may be tested observationally, and show how it may be used to determine from observation both the properties of accretion flows and the internal structure of neutron stars, including the relative inertial moments of the crust and superfluid neutron core, the crust-core coupling time, and the frequencies of any low-frequency internal collective modes. Particular attention is paid to the physical origin of spin-down episodes; it is shown that usyc episodes may result either from external torque reversals or from internal torque variations.With the aid of the statistical description, the response of the star to torque fluctuations is calculated for three stellar models: (i) a completely rigid star; (ii) a two-component star; and (iii) a two-component star with a finite-frequency internal mode, such as the Tkachenko mode of a rotating neutron superfluid. Our calculations show that fluctuating torques could account for the period the period variations and spin-down episodes observed in Her X-1 and Cen X-3, including the large spin-down event observed in the latter source during 1972 September-October. The torque noise strengths inferred from current timing observations using the simple two-component models are shown to be consistent with those to be expected from fluctuations in accretion flows onto magnetic neutron stars

University Technology Transfer: In Tough Economic Times

Science.gov (United States)

Powers, Joshua B.; Campbell, Eric G.

2009-01-01

In 1907, Frederick Cottrell, professor of chemistry at the University of California-Berkeley and father of the modern academic patent, worried that if universities became too directly involved in patenting and licensing operations, their thirst for profits could lead to the erosion of the openness necessary for academic science to flourish. For…

Phenomenology of the Gowdy Universe on $T^3 \\times R$

OpenAIRE

Berger, Beverly K.; Garfinkle, David

1997-01-01

Numerical studies of the plane symmetric, vacuum Gowdy universe on $T^3 \\times R$ yield strong support for the conjectured asymptotically velocity term dominated (AVTD) behavior of its evolution toward the singularity except, perhaps, at isolated spatial points. A generic solution is characterized by spiky features and apparent ``discontinuities'' in the wave amplitudes. It is shown that the nonlinear terms in the wave equations drive the system generically to the ``small velocity'' AVTD regi...

Observed variations in U.S. frost timing linked to atmospheric circulation patterns.

Science.gov (United States)

Strong, Courtenay; McCabe, Gregory J

2017-05-23

Several studies document lengthening of the frost-free season within the conterminous United States (U.S.) over the past century, and report trends in spring and fall frost timing that could stem from hemispheric warming. In the absence of warming, theory and case studies link anomalous frost timing to atmospheric circulation anomalies. However, recent efforts to relate a century of observed changes in U.S. frost timing to various atmospheric circulations yielded only modest correlations, leaving the relative importance of circulation and warming unclear. Here, we objectively partition the U.S. into four regions and uncover atmospheric circulations that account for 25-48% of spring and fall-frost timing. These circulations appear responsive to historical warming, and they consistently account for more frost timing variability than hemispheric or regional temperature indices. Reliable projections of future variations in growing season length depend on the fidelity of these circulation patterns in global climate models.

Result Variation and Efficiency Kinetics in Real-Time PCR

Directory of Open Access Journals (Sweden)

Reza Shahsiah

2010-10-01

Full Text Available Fluorescent monitoring of DNA amplification is the basis of real-time PCR. Absolute quantification can be achieved using a standard curve method. The standard curve is constructed by amplifying known amounts of standards under identical conditions to that of the samples.The objective of the current study is to propose a mathematical model to assess the acceptability of PCR resulys.Four commercial standards for HCV-RNA (hepatitis C virus RNA along with 6 patient samples were measured by real-time PCR, using two different RT-PCR reagents. The standard deviation of regression (Sy,x was calculated for each group of standard and compared by F-Test. The efficiency kinetics was computed by logistic regression, c2 goodness of fit test was preformed to assess the appropriateness of the efficiency curves.Calculated efficiencies were not significantly different from the value predicted by logistic regression model. Reactions with more variation showed less stable efficiency curves, with wider range of amplification efficiencies.Amplification efficiency kinetics can be computed by fitting a logistic regression curve to the gathered fluorescent data of each reaction. This model can be employed to assess the acceptability of PCR results calculated by standard curve method.

Cross-Sectional Distribution of GARCH Coefficients across S&P 500 Constituents: Time-Variation over the Period 2000-2012

OpenAIRE

David Ardia; Lennart F. Hoogerheide

2013-01-01

We investigate the time-variation of the cross-sectional distribution of asymmetric GARCH model parameters over the S&P 500 constituents for the period 2000-2012. We find the following results. First, the unconditional variances in the GARCH model obviously show major time-variation, with a high level after the dot-com bubble and the highest peak in the latest financial crisis. Second, in these more volatile periods it is especially the persistence of deviations of volatility from is uncondit...

Unit Level Variations And Peer Influences In Mental Health Diagnoses In The U.S. Army

Science.gov (United States)

2017-12-01

Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202- 4302, and to the Office of Management and Budget...variations across units without unobserved time-invariant differences such as culture or leadership style , as well as effects of time-variant variables...Nanyang Technological University, 2008 Submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE IN MANAGEMENT from the

The association between time perspective and alcohol consumption in university students: cross-sectional study.

Science.gov (United States)

Beenstock, Jane; Adams, Jean; White, Martin

2011-08-01

Heavy alcohol consumption is associated with significant morbidity and mortality. Levels of alcohol consumption among students and young people are particularly high. Time perspective describes the varying value individuals place on outcomes in the present and future. In general, it has been found that individuals prefer to receive a gain today rather than in the future. There is evidence that time perspective is associated with addictive health behaviours, including alcoholism and cigarette smoking, but less evidence of its association with non-addictive, but hazardous, levels of alcohol consumption. The objective was to determine if there is an association between time perspective and hazardous alcohol consumption. A cross-sectional survey using a self-completion questionnaire was administered to willing undergraduate students attending a convenience sample of lectures in two university faculties. Hazardous alcohol consumption was defined as a score of ≥8 on the Alcohol Use Disorders Identification Test (AUDIT) and time perspective was measured using the Consideration of Future Consequences Scale (CFCS). Participants were 322 undergraduate university students in two faculties at a university in Northern England, UK. Hazardous alcohol consumption was reported by 264 (82%) respondents. After controlling for potential confounding by socio-demographic variables, greater consideration of future consequences was associated with lower odds of reporting hazardous drinking [odds ratio = 0.28; 95% confidence interval 0.15-0.54]. Interventions aimed at increasing future orientated time perspective may be effective in decreasing hazardous alcohol consumption in students.

Pre-Big Bang, space-time structure, asymptotic Universe. Spinorial space-time and a new approach to Friedmann-like equations

Science.gov (United States)

Gonzalez-Mestres, Luis

2014-04-01

Planck and other recent data in Cosmology and Particle Physics can open the way to controversial analyses concerning the early Universe and its possible ultimate origin. Alternatives to standard cosmology include pre-Big Bang approaches, new space-time geometries and new ultimate constituents of matter. Basic issues related to a possible new cosmology along these lines clearly deserve further exploration. The Planck collaboration reports an age of the Universe t close to 13.8 Gyr and a present ratio H between relative speeds and distances at cosmic scale around 67.3 km/s/Mpc. The product of these two measured quantities is then slightly below 1 (about 0.95), while it can be exactly 1 in the absence of matter and cosmological constant in patterns based on the spinorial space-time we have considered in previous papers. In this description of space-time we first suggested in 1996-97, the cosmic time t is given by the modulus of a SU(2) spinor and the Lundmark-Lemaître-Hubble (LLH) expansion law turns out to be of purely geometric origin previous to any introduction of standard matter and relativity. Such a fundamental geometry, inspired by the role of half-integer spin in Particle Physics, may reflect an equilibrium between the dynamics of the ultimate constituents of matter and the deep structure of space and time. Taking into account the observed cosmic acceleration, the present situation suggests that the value of 1 can be a natural asymptotic limit for the product H t in the long-term evolution of our Universe up to possible small corrections. In the presence of a spinorial space-time geometry, no ad hoc combination of dark matter and dark energy would in any case be needed to get an acceptable value of H and an evolution of the Universe compatible with observation. The use of a spinorial space-time naturally leads to unconventional properties for the space curvature term in Friedmann-like equations. It therefore suggests a major modification of the standard

Variation in Annual Volume at a University Hospital Does Not Predict Mortality for Pancreatic Resections

Directory of Open Access Journals (Sweden)

Rita A. Mukhtar

2008-01-01

Full Text Available Annual volume of pancreatic resections has been shown to affect mortality rates, prompting recommendations to regionalize these procedures to high-volume hospitals. Implementation has been difficult, given the paucity of high-volume centers and the logistical hardships facing patients. Some studies have shown that low-volume hospitals achieve good outcomes as well, suggesting that other factors are involved. We sought to determine whether variations in annual volume affected patient outcomes in 511 patients who underwent pancreatic resections at the University of California, San Francisco between 1990 and 2005. We compared postoperative mortality and complication rates between low, medium, or high volume years, designated by the number of resections performed, adjusting for patient characteristics. Postoperative mortality rates did not differ between high volume years and medium/low volume years. As annual hospital volume of pancreatic resections may not predict outcome, identification of actual predictive factors may allow low-volume centers to achieve excellent outcomes.

Accrediting High-School Students' Part-Time Work to Support Effective Transitions to, through and beyond University

Science.gov (United States)

Evans, Carl; Richardson, Mark

2018-01-01

Models of accrediting work-based learning are now commonplace in universities. The purpose of this viewpoint article is to highlight an opportunity for universities not only to accredit students' part-time work against the degree award but also to extend the process into schools by accrediting the part-time work undertaken by year 12 and 13…

Discretization of space and time: mass-energy relation, accelerating expansion of the Universe, Hubble constant

OpenAIRE

Roatta , Luca

2017-01-01

Assuming that space and time can only have discrete values, we obtain the expression of the gravitational potential energy that at large distance coincides with the Newtonian. In very precise circumstances it coincides with the relativistic mass-energy relation: this shows that the Universe is a black hole in which all bodies are subjected to an acceleration toward the border of the Universe itself. Since the Universe is a black hole with a fixed radius, we can obtain the density of the Unive...

Derivation of an adiabatic time-dependent Hartree-Fock formalism from a variational principle

International Nuclear Information System (INIS)

Brink, D.M.; Giannoni, M.J.; Veneroni, M.

1975-10-01

A derivation of the adiabatic time-dependent Hartree-Fock formalism is given, which is based on a variational principle analogous to Hamilton's principle in classical mechanics. The method leads to a Hamiltonian for collective motion which separates into a potential and a kinetic energy and gives mass and potential parameters in terms of the nucleon-nucleon interaction. The adiabatic approximation assumes slow motion but not small amplitudes and can therefore describe anharmonic effects. The RPA is a limiting case where both amplitudes and velocities are small. The variational approach provides a consistent way of extracting coordinated and momenta from the density matrix and of obtaining equations of motion when particular trial forms for this density matrix are chosen. One such choice leads to Thouless-Valatin formula. An other choice leads to irrotational hydrodynamics [fr

Variational Symplectic Integrator for Long-Time Simulations of the Guiding-Center Motion of Charged Particles in General Magnetic Fields

International Nuclear Information System (INIS)

Qin Hong; Guan Xiaoyin

2008-01-01

A variational symplectic integrator for the guiding-center motion of charged particles in general magnetic fields is developed for long-time simulation studies of magnetized plasmas. Instead of discretizing the differential equations of the guiding-center motion, the action of the guiding-center motion is discretized and minimized to obtain the iteration rules for advancing the dynamics. The variational symplectic integrator conserves exactly a discrete Lagrangian symplectic structure, and has better numerical properties over long integration time, compared with standard integrators, such as the standard and variable time-step fourth order Runge-Kutta methods

Variational Symplectic Integrator for Long-Time Simulations of the Guiding-Center Motion of Charged Particles in General Magnetic Fields

International Nuclear Information System (INIS)

Qin, H.; Guan, X.

2008-01-01

A variational symplectic integrator for the guiding-center motion of charged particles in general magnetic fields is developed for long-time simulation studies of magnetized plasmas. Instead of discretizing the differential equations of the guiding-center motion, the action of the guiding-center motion is discretized and minimized to obtain the iteration rules for advancing the dynamics. The variational symplectic integrator conserves exactly a discrete Lagrangian symplectic structure, and has better numerical properties over long integration time, compared with standard integrators, such as the standard and variable time-step fourth order Runge-Kutta methods.

Observer variation in skeletal radiology

Energy Technology Data Exchange (ETDEWEB)

Cockshott, W.P.; Park, W.M.

1983-08-01

The factors that affect observer variation in bone radiology are analysed from data in the literature and on the basis of studies carried out at McMaster University on the hands and sacroiliac joints. A plea is made for presenting results in terms of Kappa statistics so that agreement due purely to chance is eliminated. In the conclusions the main variables that affect concordance are listed so that strategies can be developed to reduce observer variation. This is important in serial studies to ensure that the observer variations are smaller than the effect one wishes to measure.

The Universe is Like a Hollowed Sphere. The Wave Concept of Time

Directory of Open Access Journals (Sweden)

Andrzej W. Głuszak

2015-07-01

Full Text Available There is space for new ideas of the essence and the entity of time. The article refers to our time concept as a special wave type and presents results of our investigations on this subject. Thus, time defined as waves and an energy carrier could give explanation to multiple unclear phenomena. It could explicate gravity, organization in the planetary systems and light speed limit. A hypothesis that matter exists due to time wave motion would emerge from the elementary particle mass generation by the waves. Time becomes the main driving force in the Universe. The discussed thoughts need further analyses and verification but their confirmation may mean civilization changes.

How the universe got its spots diary of a finite time in a finite space

CERN Document Server

Levin, Janna

2002-01-01

Is the universe infinite, or is it just really big? Does nature abhor infinity? In startling and beautiful prose, Janna Levin's diary of unsent letters to her mother describes what we know about the shape and extent of the universe, about its beginning and its end. She grants the uninitiated access to the astounding findings of contemporary theoretical physics and makes tangible the contours of space and time--those very real curves along which apples fall and planets orbit. Levin guides the reader through the observations and thought-experiments that have enabled physicists to begin charting the universe. She introduces the cosmic archaeology that makes sense of the pattern of hot spots left over from the big bang, a pursuit on the verge of discovering the shape of space itself. And she explains the topology and the geometry of the universe now coming into focus--a strange map of space full of black holes, chaotic flows, time warps, and invisible strings. Levin advances the controversial idea that this map ...

The pattern of time management in college students of Kerman University of Medical Sciences in the year 2006

OpenAIRE

Ali Ravari; Fatemeh Alhani; Monireh Anoosheh; Tayebeh Mirzaie-Khalilabadi

2008-01-01

Background: One potential coping strategy frequently offered by university counseling services is time management for studying. Besides stress relief, time management skills will positively influence key outcomes such as academic performance, problem-solving ability, and health. Thus, it is necessary to investigate how college students manage their timing for studying. The aim of the present study was to assess the pattern of college students' time management in Kerman University of Medical S...

Stability of cylindrical thin shell wormhole during evolution of universe from inflation to late time acceleration

Energy Technology Data Exchange (ETDEWEB)

Setare, M.R. [Department of Science, Campus of Bijar, University of Kurdistan,Bijar (Iran, Islamic Republic of); Sepehri, A. [Faculty of Physics, Shahid Bahonar University,P.O. Box 76175, Kerman (Iran, Islamic Republic of)

2015-03-16

In this paper, we consider the stability of cylindrical wormholes during evolution of universe from inflation to late time acceleration epochs. We show that there are two types of cylindrical wormholes. The first type is produced at the corresponding point where k black F-strings are transited to BIon configuration. This wormhole transfers energy from extra dimensions into our universe, causes inflation, loses it’s energy and vanishes. The second type of cylindrical wormhole is created by a tachyonic potential and causes a new phase of acceleration. We show that wormhole parameters grow faster than the scale factor in this era, overtake it at ripping time and lead to the destruction of universe at big rip singularity.

Leisure-time physical activity and psychological well-being in university students.

Science.gov (United States)

Molina-García, J; Castillo, I; Queralt, A

2011-10-01

An analysis of psychological well-being (self-esteem and subjective vitality) of 639 Spanish university students was performed, while accounting for the amount of leisure-time physical activity. The Spanish versions of the Rosenberg Self-Esteem Scale and Subjective Vitality Scale were employed. Participants were divided into four groups (Low, Moderate, High, and Very high) depending on estimation of energy expenditure in leisure-time physical activity. Men and women having higher physical activity rated higher mean subjective vitality; however, differences in self-esteem were observed only in men, specifically between Very high and the other physical activity groups.

The Influence of Personal Well-Being on Learning Achievement in University Students Over Time: Mediating or Moderating Effects of Internal and External University Engagement

Directory of Open Access Journals (Sweden)

Lu Yu

2018-01-01

Full Text Available The current study examined the relationship between students' personal well-being and their learning achievement during university study, and whether such relationship would be mediated or moderated by university engagement. A total of 434 university students from one public university in Hong Kong participated in the study. The participants completed an online survey consisting of personal well-being (cognitive behavioral competence and general positive youth development, university engagement, and learning achievement measures (personal growth, and accumulated GPA as academic achievement at four time points with a 1-year interval. Results showed that personal well-being measured at the beginning of university study positively predicted students' personal growth and academic achievement after 3 years' study. While the internal dimensions of university engagement (academic challenge and learning with peers showed longitudinal significant mediational effect, the external dimensions (experience with faculty and campus environment did not have significant longitudinal moderating effect. Nevertheless, external dimensions of student engagement also showed direct effect on personal growth and academic achievement. The long-standing positive effects of personal well-being on university engagement and subsequently, learning achievement during university years call for more attention to the promotion of holistic development among university students in Hong Kong.

The Influence of Personal Well-Being on Learning Achievement in University Students Over Time: Mediating or Moderating Effects of Internal and External University Engagement

Science.gov (United States)

Yu, Lu; Shek, Daniel T. L.; Zhu, Xiaoqin

2018-01-01

The current study examined the relationship between students' personal well-being and their learning achievement during university study, and whether such relationship would be mediated or moderated by university engagement. A total of 434 university students from one public university in Hong Kong participated in the study. The participants completed an online survey consisting of personal well-being (cognitive behavioral competence and general positive youth development), university engagement, and learning achievement measures (personal growth, and accumulated GPA as academic achievement) at four time points with a 1-year interval. Results showed that personal well-being measured at the beginning of university study positively predicted students' personal growth and academic achievement after 3 years' study. While the internal dimensions of university engagement (academic challenge and learning with peers) showed longitudinal significant mediational effect, the external dimensions (experience with faculty and campus environment) did not have significant longitudinal moderating effect. Nevertheless, external dimensions of student engagement also showed direct effect on personal growth and academic achievement. The long-standing positive effects of personal well-being on university engagement and subsequently, learning achievement during university years call for more attention to the promotion of holistic development among university students in Hong Kong. PMID:29375421

Variation in timing of ossification affects inferred heterochrony of cranial bones in Lissamphibia.

Science.gov (United States)

Sheil, Christopher A; Jorgensen, Michael; Tulenko, Frank; Harrington, Sean

2014-09-01

The evolutionary origin of Lissamphibia likely involved heterochrony, as demonstrated by the biphasic lifestyles of most extant orders, differences between Anura (with tadpole-to-froglet metamorphosis) and Urodela (which lack strongly defined metamorphosis), and the appearance of direct development among separate lineages of frogs. Patterns in the timing of appearance of skeletal elements (i.e., ossification sequence data) represent a possible source of information for understanding the origin of Lissamphibia, and with the advent of analytical methods to directly optimize these data onto known phylogenies, there has been a renewed interest in assessing the role of changes in these developmental events. However, little attention has been given to the potential impact of variation in ossification sequence data--this is particularly surprising given that different criteria for collecting these data have been employed. Herein, new and previously published ossification data are compiled and all pairs of data for same-species comparisons are selected. Analyses are run to assess the impact of using data that were collected by different methodologies: (1) wild- versus lab-raised animals; (2) different criteria for recognizing timing of ossification; and (3) randomly selecting ossification sequences for species from which multiple studies have been published, but for which the data were collected by different criteria. Parsimov-based genetic inference is utilized to map ossification sequence data onto an existing phylogeny to reconstruct ancestral sequences of ossification and infer instances of heterochrony. All analyses succeeded in optimizing sequence data on internal nodes and instances of heterochrony were identified. However, among all analyses little congruence was found in reconstructed ancestral sequences or among inferred instances of heterochrony. These results indicate a high degree of variation in timing of ossification, and suggest a cautionary note about use

Measuring Chemotherapy Appointment Duration and Variation Using Real-Time Location Systems.

Science.gov (United States)

Barysauskas, Constance M; Hudgins, Gina; Gill, Katie Kupferberg; Camuso, Kristen M; Bagley, Janet; Rozanski, Sheila; Kadish, Sarah

Clinical schedules drive resource utilization, cost, and patient wait time. Accurate appointment duration allocation ensures appropriate staffing ratios to daily caseloads and maximizes scarce resources. Dana-Farber Cancer Institute (DFCI) infusion appointment duration is adjusted by regimen using a consensus method of experts including pharmacists, nurses, and administrators. Using real-time location system (RTLS), we examined the accuracy of observed appointment duration compared with the scheduled duration. Appointment duration was calculated using RTLS at DFCI between August 1, 2013, and September 30, 2013. Duration was defined as the total time a patient occupied an infusion chair. The top 10 administered infusion regimens were investigated (n = 805). Median observed appointment durations were statistically different than the scheduled durations. Appointment durations were shorter than scheduled 98% (C), 95% (I), and 75% (F) of the time and longer than scheduled 77% (A) and 76% (G) of the time. Fifty-six percent of the longer than scheduled (A) appointments were at least 30 minute longer. RTLS provides reliable and unbiased data to improve schedule accuracy. Replacing consensus with system-based data may improve clinic flow, relieve staff stress, and increase patient satisfaction. Further investigation is warranted to elucidate factors that impact variation in appointment duration.

Effects of detector–source distance and detector bias voltage variations on time resolution of general purpose plastic scintillation detectors

International Nuclear Information System (INIS)

Ermis, E.E.; Celiktas, C.

2012-01-01

Effects of source-detector distance and the detector bias voltage variations on time resolution of a general purpose plastic scintillation detector such as BC400 were investigated. 133 Ba and 207 Bi calibration sources with and without collimator were used in the present work. Optimum source-detector distance and bias voltage values were determined for the best time resolution by using leading edge timing method. Effect of the collimator usage on time resolution was also investigated. - Highlights: ► Effect of the source-detector distance on time spectra was investigated. ► Effect of the detector bias voltage variations on time spectra was examined. ► Optimum detector–source distance was determined for the best time resolution. ► Optimum detector bias voltage was determined for the best time resolution. ► 133 Ba and 207 Bi radioisotopes were used.

Time Variations of the Radial Velocity of H2O Masers in the Semi-Regular Variable R Crt

Science.gov (United States)

Sudou, Hiroshi; Shiga, Motoki; Omodaka, Toshihiro; Nakai, Chihiro; Ueda, Kazuki; Takaba, Hiroshi

2017-12-01

H2O maser emission {at 22 GHz} in the circumstellar envelope is one of the good tracers of detailed physics and inematics in the mass loss process of asymptotic giant branch stars. Long-term monitoring of an H2O maser spectrum with high time resolution enables us to clarify acceleration processes of the expanding shell in the stellar atmosphere. We monitored the H2O maser emission of the semi-regular variable R Crt with the Kagoshima 6-m telescope, and obtained a large data set of over 180 maser spectra over a period of 1.3 years with an observational span of a few days. Using an automatic peak detection method based on least-squares fitting, we exhaustively detected peaks as significant velocity components with the radial velocity on a 0.1 km s^{-1} scale. This analysis result shows that the radial velocity of red-shifted and blue-shifted components exhibits a change between acceleration and deceleration on the time scale of a few hundred days. These velocity variations are likely to correlate with intensity variations, in particular during flaring state of H2O masers. It seems reasonable to consider that the velocity variation of the maser source is caused by shock propagation in the envelope due to stellar pulsation.However, it is difficult to explain the relationship between the velocity variation and the intensity variation only from shock propagation effects. We found that a time delay of the integrated maser intensity with respect to the optical light curve is about 150 days.

Time series analysis of diverse extreme phenomena: universal features

Science.gov (United States)

Eftaxias, K.; Balasis, G.

2012-04-01

The field of study of complex systems holds that the dynamics of complex systems are founded on universal principles that may used to describe a great variety of scientific and technological approaches of different types of natural, artificial, and social systems. We suggest that earthquake, epileptic seizures, solar flares, and magnetic storms dynamics can be analyzed within similar mathematical frameworks. A central property of aforementioned extreme events generation is the occurrence of coherent large-scale collective behavior with very rich structure, resulting from repeated nonlinear interactions among the corresponding constituents. Consequently, we apply the Tsallis nonextensive statistical mechanics as it proves an appropriate framework in order to investigate universal principles of their generation. First, we examine the data in terms of Tsallis entropy aiming to discover common "pathological" symptoms of transition to a significant shock. By monitoring the temporal evolution of the degree of organization in time series we observe similar distinctive features revealing significant reduction of complexity during their emergence. Second, a model for earthquake dynamics coming from a nonextensive Tsallis formalism, starting from first principles, has been recently introduced. This approach leads to an energy distribution function (Gutenberg-Richter type law) for the magnitude distribution of earthquakes, providing an excellent fit to seismicities generated in various large geographic areas usually identified as seismic regions. We show that this function is able to describe the energy distribution (with similar non-extensive q-parameter) of solar flares, magnetic storms, epileptic and earthquake shocks. The above mentioned evidence of a universal statistical behavior suggests the possibility of a common approach for studying space weather, earthquakes and epileptic seizures.

Divorce risk factors and their variation over time in Spain

Directory of Open Access Journals (Sweden)

Fabrizio Bernardi

2011-05-01

Full Text Available The aim of this article is to analyse the determinants of marriage dissolution in Spain and their variation over time for women married between 1949 and 2006. Data are drawn from the Survey of Fertility, Family and Values of 2006. The article analyses the transition from first marriage to marital dissolution for couples who married in two eras: one prior to the Divorce Law of 1981, during which social and legal barriers to dissolution were many, and one in the period after the law was introduced, during which barriers to marriage dissolution were far fewer. Analyses are conducted using a continuous time event history model. The results indicate some similarities between Spain and other countries, such as the positive relationship between the typical features of unconventional families and marital dissolution, but also some specific differences, such as an increase in the importance of premarital pregnancy and/or not having children. It is also important to stress the declining importance of socio-economic variables, such as education and the labour market situation of women.

Excitation of Earth Rotation Variations "Observed" by Time-Variable Gravity

Science.gov (United States)

Chao, Ben F.; Cox, C. M.

2005-01-01

Time variable gravity measurements have been made over the past two decades using the space geodetic technique of satellite laser ranging, and more recently by the GRACE satellite mission with improved spatial resolutions. The degree-2 harmonic components of the time-variable gravity contain important information about the Earth s length-of-day and polar motion excitation functions, in a way independent to the traditional "direct" Earth rotation measurements made by, for example, the very-long-baseline interferometry and GPS. In particular, the (degree=2, order= 1) components give the mass term of the polar motion excitation; the (2,O) component, under certain mass conservation conditions, gives the mass term of the length-of-day excitation. Combining these with yet another independent source of angular momentum estimation calculated from global geophysical fluid models (for example the atmospheric angular momentum, in both mass and motion terms), in principle can lead to new insights into the dynamics, particularly the role or the lack thereof of the cores, in the excitation processes of the Earth rotation variations.

Time dependent variation of carrying capacity of prestressed precast beam

Science.gov (United States)

Le, Tuan D.; Konečný, Petr; Matečková, Pavlína

2018-04-01

The article deals with the evaluation of the precast concrete element time dependent carrying capacity. The variation of the resistance is inherited property of laboratory as well as in-situ members. Thus the specification of highest, yet possible, laboratory sample resistance is important with respect to evaluation of laboratory experiments based on the test machine loading capabilities. The ultimate capacity is evaluated through the bending moment resistance of a simply supported prestressed concrete beam. The probabilistic assessment is applied. Scatter of random variables of compressive strength of concrete and effective height of the cross section is considered. Monte Carlo simulation technique is used to investigate the performance of the cross section of the beam with changes of tendons’ positions and compressive strength of concrete.

Menstrual variation of breast volume and T2 relaxation times in cyclical mastalgia

International Nuclear Information System (INIS)

Hussain, Zainab; Brooks, Jonathan; Percy, Dave

2008-01-01

Purpose: Hormonal activity causes breast volume to change during the menstrual cycle. One possible cause of this volume change is thought to be due to water retention or oedema within the tissues. We used magnetic resonance imaging (MRI) to study the variation in breast volume and 1 H Magnetic Resonance Spectroscopy (MRS) to measure T 2 relaxation times which are known to increase with increasing tissue water content. We hypothesised that an increase in breast volume will elevate T 2 relaxation due to the presence of an increased water content within the breast. T 2 Relaxation time and volume were studied in fifteen control subjects and in a cohort of eight patients with cyclical mastalgia in order to determine whether changes in breast volume and T 2 relaxation times differed in controls and patients during menses, ovulation and premenses. Method: Breast volume was determined by the Cavalieri method in combination with point counting techniques on MR images and T 2 relaxation times of the water and fat in a voxel of breast tissue were obtained using 1 H Magnetic Resonance Spectroscopy (MRS). Results: Statistical analysis (ANOVA) demonstrated highly significant differences in breast volume between the three stages of the cycle (p 2 of fat or water did not depend on stage of cycle. T-tests demonstrated no significant differences in T 2 of water or fat between patient and control groups. The average T 2 relaxation time of water was lowest in the patient and control groups during ovulation and highest in the patient group during premenses. Conclusion: We have performed the first combined volumetric and spectroscopic study of women with cyclical mastalgia and demonstrated that the global changes in volumes and T 2 were not significantly different from normal menstrual variations

Storm Time Variation of Radiative Cooling by Nitric Oxide as Observed by TIMED-SABER and GUVI

Science.gov (United States)

Bharti, Gaurav; Sunil Krishna, M. V.; Bag, T.; Jain, Puneet

2018-02-01

The variation of O/N2 (reference to N2 column density 1017 cm-2) and nitric oxide radiative emission flux exiting the thermosphere have been studied over the Northern Hemisphere during the superstorm event of 7-12 November 2004. The data have been obtained from Global Ultraviolet Imager (GUVI) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on board the National Aeronautics and Space Administration (NASA)'s Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite. The NO radiative flux is observed to show an anti-correlation with O/N2 on a global scale. Both NO radiative flux and O/N2 ratio show equatorward motion with maximum penetration in western longitude sectors. A local variation of O, O2, and N2 densities have been calculated using NRLMSISE-00 model over a midlatitude location (55°N,180°E). On a local scale, model calculated O/O2 and O/N2 ratios are found to follow the observations made by GUVI. The collisional excitation of NO with atomic oxygen is the most dominant process for the total cooling rate. The SABER-retrieved NO cooling rate (CR) at a local site suggests an enhancement during the storm period with the peak emission rate closely correlated to the progression of the storm. The peak emission altitude of NO CR moves upward during the main phase of the storm. The NO abundance has been calculated by using cooling rate and Nitric Oxide Empirical Model (NOEM) model. Both these suggest a vary large (3-15 times) increase in NO density during the storm, which is required to account the changes in NO radiative flux. A similar kind of enhancement in NO abundance is also noticed in Student Nitric Oxide Explorer observations during intense geomagnetic storms.

Time Variations of the Spectral Indices of the Suprathermal Distribution as observed by WIND/STICS

Science.gov (United States)

Gruesbeck, J. R.; Christian, E. R.; Lepri, S. T.; Thomas, J.; Zurbuchen, T.; Gloeckler, G.

2011-12-01

Suprathermal particle spectra, measured in various regions of the heliosphere and heliosheath by Ulysses, ACE and Voyager, have recently been reported. In many cases long accumulation times had to be used to obtain sufficient statistical accuracy, and corrections were necessary, since only a fraction of phase space was measured. The SupraThermal Ion Composition Spectrometer (STICS), onboard Wind, enables observations of the suprathermal plasma in the solar wind at much higher time resolution. In addition, the STICS samples nearly full three-dimensional phase space, enabling measurements of anisotropies. We present a multi-year investigation of the spectral index of the suprathermal distribution, accumulated over 1 day and less, where we see significant time variation. An average lower bound value of the spectral index is at ~ -5, however, there are time periods during which the observed distributions steepen. We will also present an analysis of time and spatial variations of the suprathermal particle fluxes, observed by STICS and other instruments. In particular, we will compare the observed variability with predictions from a model by Bochsler and Moebius, based on data of the Interstellar Boundary Explorer (IBEX), who postulated that energetic neutral atoms, from outside of the heliosheath, which then penetrate the inner heliosphere and are finally ionized, could be a source of the very suprathermal populations we observe.

Exact solutions, finite time singularities and non-singular universe models from a variety of Λ(t) cosmologies

Science.gov (United States)

Pan, Supriya

2018-01-01

Cosmological models with time-dependent Λ (read as Λ(t)) have been investigated widely in the literature. Models that solve background dynamics analytically are of special interest. Additionally, the allowance of past or future singularities at finite cosmic time in a specific model signals for a generic test on its viabilities with the current observations. Following these, in this work we consider a variety of Λ(t) models focusing on their evolutions and singular behavior. We found that a series of models in this class can be exactly solved when the background universe is described by a spatially flat Friedmann-Lemaître-Robertson-Walker (FLRW) line element. The solutions in terms of the scale factor of the FLRW universe offer different universe models, such as power-law expansion, oscillating, and the singularity free universe. However, we also noticed that a large number of the models in this series permit past or future cosmological singularities at finite cosmic time. At last we close the work with a note that the avoidance of future singularities is possible for certain models under some specific restrictions.

SABER (TIMED) and MLS (UARS) Temperature Observations of Mesospheric and Stratospheric QBO and Related Tidal Variations

Science.gov (United States)

Huang, Frank T.; Mayr, Hans G.; Reber, Carl A.; Russell, James; Mlynczak, Marty; Mengel, John

2006-01-01

More than three years of temperature observations from the SABER (TIMED) and MLS WARS) instruments are analyzed to study the annual and inter-annual variations extending from the stratosphere into the upper mesosphere. The SABER measurements provide data from a wide altitude range (15 to 95 km) for the years 2002 to 2004, while the MLS data were taken in the 16 to 55 km altitude range a decade earlier. Because of the sampling properties of SABER and MLS, the variations with local solar time must be accounted for when estimating the zonal mean variations. An algorithm is thus applied that delineates with Fourier analysis the year-long variations of the migrating tides and zonal mean component. The amplitude of the diurnal tide near the equator shows a strong semiannual periodicity with maxima near equinox, which vary from year to year to indicate the influence from the Quasi-biennial Oscillation (QBO) in the zonal circulation. The zonal mean QBO temperature variations are analyzed over a range of latitudes and altitudes, and the results are presented for latitudes from 48"s to 48"N. New results are obtained for the QBO, especially in the upper stratosphere and mesosphere, and at mid-latitudes. At Equatorial latitudes, the QBO amplitudes show local peaks, albeit small, that occur at different altitudes. From about 20 to 40 km, and within about 15" of the Equator, the amplitudes can approach 3S K for the stratospheric QBO or SQBO. For the mesospheric QBO or MQBO, we find peaks near 70 km, with temperature amplitudes reaching 3.5"K, and near 85 km, the amplitudes approach 2.5OK. Morphologically, the amplitude and phase variations derived from the SABER and MLS measurements are in qualitative agreement. The QBO amplitudes tend to peak at the Equator but then increase again pole-ward of about 15" to 20'. The phase progression with altitude varies more gradually at the Equator than at mid-latitudes. A comparison of the observations with results from the Numerical Spectral

Local Times of Galactic Cosmic Ray Intensity Maximum and Minimum in the Diurnal Variation

Directory of Open Access Journals (Sweden)

Su Yeon Oh

2006-06-01

Full Text Available The Diurnal variation of galactic cosmic ray (GCR flux intensity observed by the ground Neutron Monitor (NM shows a sinusoidal pattern with the amplitude of 1sim 2 % of daily mean. We carried out a statistical study on tendencies of the local times of GCR intensity daily maximum and minimum. To test the influences of the solar activity and the location (cut-off rigidity on the distribution in the local times of maximum and minimum GCR intensity, we have examined the data of 1996 (solar minimum and 2000 (solar maximum at the low-latitude Haleakala (latitude: 20.72 N, cut-off rigidity: 12.91 GeV and the high-latitude Oulu (latitude: 65.05 N, cut-off rigidity: 0.81 GeV NM stations. The most frequent local times of the GCR intensity daily maximum and minimum come later about 2sim3 hours in the solar activity maximum year 2000 than in the solar activity minimum year 1996. Oulu NM station whose cut-off rigidity is smaller has the most frequent local times of the GCR intensity maximum and minimum later by 2sim3 hours from those of Haleakala station. This feature is more evident at the solar maximum. The phase of the daily variation in GCR is dependent upon the interplanetary magnetic field varying with the solar activity and the cut-off rigidity varying with the geographic latitude.

Midlatitude D region variations measured from broadband radio atmospherics

Science.gov (United States)

Han, Feng

The high power, broadband very low frequency (VLF, 3--30 kHz) and extremely low frequency (ELF, 3--3000 Hz) electromagnetic waves generated by lightning discharges and propagating in the Earth-ionosphere waveguide can be used to measure the average electron density profile of the lower ionosphere (D region) across the wave propagation path due to several reflections by the upper boundary (lower ionosphere) of the waveguide. This capability makes it possible to frequently and even continuously monitor the D region electron density profile variations over geographically large regions, which are measurements that are essentially impossible by other means. These guided waves, usually called atmospherics (or sferics for short), are recorded by our sensors located near Duke University. The purpose of this work is to develop and implement algorithms to derive the variations of D region electron density profile which is modeled by two parameters (one is height and another is sharpness), by comparing the recorded sferic spectra to a series of model simulated sferic spectra from using a finite difference time domain (FDTD) code. In order to understand the time scales, magnitudes and sources for the midlatitude nighttime D region variations, we analyzed the sferic data of July and August 2005, and extracted both the height and sharpness of the D region electron density profile. The heights show large temporal variations of several kilometers on some nights and the relatively stable behavior on others. Statistical calculations indicate that the hourly average heights during the two months range between 82.0 km and 87.2 km with a mean value of 84.9 km and a standard deviation of 1.1 km. We also observed spatial variations of height as large as 2.0 km over 5 degrees latitudes on some nights, and no spatial variation on others. In addition, the measured height variations exhibited close correlations with local lightning occurrence rate on some nights but no correlation with local

Time variation of the cosmological redshift in Dicke-Brans-Jordan cosmologies

International Nuclear Information System (INIS)

Ruediger, R.

1982-01-01

In this paper the time variation z of the cosmological redshift z is discussed for Dicke-Brans-Jordan (DBJ) cosmologies. We determine the general z-z relation in the functional form zH -1 0 = F(z; q 0 , sigma 0 ,xi 0 , ω) for small values of z, where all the symbols have their conventional meanings. For certain combinations of cosmological parameters, which are within the present observational limitations, the DBJ terms in the function F can dominate the general relativistic terms. Furthermore, zH -1 0 can be positive in DBJ cosmologies in contrast to general relativistic cosmologies with q 0 >0

Novel approach for evaluation of air change rate in naturally ventilated occupied spaces based on metabolic CO2 time variation

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Markov, Detelin G.

2014-01-01

IAQ in many residential buildings relies on non-organized natural ventilation. Accurate evaluation of air change rate (ACR) in this situation is difficult due to the nature of the phenomenon - intermittent infiltration-exfiltration periods of mass exchange between the room air and the outdoor air...... at low rate. This paper describes a new approach for ACR evaluation in naturally ventilated occupied spaces. Actual metabolic CO2 time variation record in an interval of time is compared with the computed variation of metabolic CO2 for the same time interval under reference conditions: sleeping occupants...

Time Resolution Dependence of Information Measures for Spiking Neurons: Scaling and Universality

Directory of Open Access Journals (Sweden)

James P Crutchfield

2015-08-01

Full Text Available The mutual information between stimulus and spike-train response is commonly used to monitor neural coding efficiency, but neuronal computation broadly conceived requires more refined and targeted information measures of input-output joint processes. A first step towards that larger goal is todevelop information measures for individual output processes, including information generation (entropy rate, stored information (statisticalcomplexity, predictable information (excess entropy, and active information accumulation (bound information rate. We calculate these for spike trains generated by a variety of noise-driven integrate-and-fire neurons as a function of time resolution and for alternating renewal processes. We show that their time-resolution dependence reveals coarse-grained structural properties of interspike interval statistics; e.g., $tau$-entropy rates that diverge less quickly than the firing rate indicate interspike interval correlations. We also find evidence that the excess entropy and regularized statistical complexity of different types of integrate-and-fire neurons are universal in the continuous-time limit in the sense that they do not depend on mechanism details. This suggests a surprising simplicity in the spike trains generated by these model neurons. Interestingly, neurons with gamma-distributed ISIs and neurons whose spike trains are alternating renewal processes do not fall into the same universality class. These results lead to two conclusions. First, the dependence of information measures on time resolution reveals mechanistic details about spike train generation. Second, information measures can be used as model selection tools for analyzing spike train processes.

Chernobyl derived activity in sheep: variation within a single flock and with time

International Nuclear Information System (INIS)

Walters, B.

1988-01-01

The continuous monitoring of the caesium contents of sheep grazing a high fell in Cumbria, UK, is described. The technique of in-vivo monitoring, using portable NaI crystal detectors, is shown to be robust and capable of producing accurate quantitative data. Results are presented from the monitoring of 100 sheep at fortnightly intervals over a period of 13 weeks. The peak average activity (1300 Bq kg -1 ) was reached five weeks after introduction of the sheep to grazing land with up to 2000 Bq kg -1 in herbage. Activity had fallen, on average, to 68% of the peak value after eight weeks. The variation in activity between individual sheep is large and usually symmetrically distributed. The temporal trend of activity in the whole flock is a combination of the many disparate individual trends. The technique has allowed the variation between animals and individual time trends to be followed. (author)

Is It Time Well Spent? The Relationship between Time Management Behaviours, Perceived Effectiveness and Work-Related Morale and Distress in a University Context

Science.gov (United States)

Kearns, Hugh; Gardiner, Maria

2007-01-01

Despite the high "guru-factor" in time management, few claims have been subjected to empirical investigation. This study tests the claims that people who manage their time well perceive themselves to be more effective and feel less stressed. University staff and students were utilized to investigate the relationship between time management related…

The need for time management training is universal: evidence from Turkey.

Science.gov (United States)

Kisa, Adnan; Ersoy, Korkut

2005-01-01

In many developing countries, healthcare administrators are currently facing challenges that are representative of those in the United States. Most healthcare administrators here are physicians with no formal training in healthcare administration, and this is perhaps most apparent in their difficulties with time management. The authors' purpose in this study was to characterize the time management difficulties of administrators working in primary healthcare facilities of the Ministry of Healthcare. In the study, 67 healthcare administrators each completed a 31-item time management questionnaire. Of the participants, 79.1% reported that they have never attended time management courses or workshops. Although 76.1% said they were free to choose the priority of their daily tasks, only 44.8% felt they knew how much time they should allow for each activity in their daily life. These and other findings in the study suggest that the need for time management education is a well-defined target for intervention, both in university-based programs for future healthcare administrators and in workplace-based programs, such as in-service training for healthcare administrators who are already working.

The Worldly Space: The Digital University in Network Time

Science.gov (United States)

Hassan, Robert

2017-01-01

This article considers the effect of information technology upon teaching, learning and research in the "digital university". In less than a generation the university has become a business like any other. It does so in the determining context of neoliberal globalisation and the computer revolution. The university develops through what we…

Storm-time variation of radiative cooling by Nitric Oxide as observed by TIMED-SABER and GUVI

Science.gov (United States)

Sunil Krishna, M. V.; Bharti, G.; Bag, T.

2017-12-01

The variation of O/N2 and nitric oxide radiative emission flux exiting thermosphere have been studied over northern hemisphere during the super-storm event of November 7-12, 2004. The data have been obtained from GUVI and SABER onboard the NASA's TIMED satellite. The NO radiative flux is observed to show an anti-correlation with O/N2 on a global scale. Both NO radiative flux and O/N2 ratio show equatorward motion with maximum penetration in western longitude sectors. A local variation of O, O2 and N2 densities have been calculated by using NRLMSISE-00 model over a mid-latitude location (55oN,180oE). On a local scale, model calculated O/O2 and O/N2 ratios are found to follow the observations made by GUVI. The SABER retrieved NO cooling rate (CR) at a local site suggests an enhancement during the storm period with the peak emission rate closely correlated to the progression of the storm. The peak emission altitude of NO CR moves upward during the main phase of the storm. The NO abundance has been calculated by using cooling rate and NOEM model. Both these suggest huge increase in NO density during the storm which is required to account the changes in NO radiative flux.

Establishing a Set of Macroeconomic Factors Explaining Variation Over Time of Performance in Business Sectors

Directory of Open Access Journals (Sweden)

Audrius Dzikevičius

2016-06-01

Full Text Available With increasing competitiveness of companies and business sectors in the domestic markets of Lithuania, economic units are frequently confronted with the lack of methods for more detailed analysis of external factors explaining the variation over time of corporate financial indicators. The analysis or forecasting of financial indicators is usually linked with the development of a stock market or undertaken to estimate the probability of bankruptcy. However, there is a lack of studies aimed at identifying links between macroeconomic factors and financial performance indicators and explaining their variation over time. To serve that purpose, the factors of the macroeconomic environment that are most significant for certain economic activities have been identified and analysed to enable explaining the variation over time patterns of corporate financial indicators. The analysis covers economic performance, i.e. financial performance indicators and their links with macroeconomic factors, in 89 business sectors of Lithuania at a three-digit level of NACE 2 ed. The findings of the research indicate that the unemployment level in the country, the volume of export and import and the GDP are the most important macroeconomic factors that can be used to forecast different profitability, financial leverage, liquidity and other financial performance indicators of individual business sectors or companies. The research has not unfolded any significant differences between business sectors therefore the above factors are considered generic macroeconomic factors enabling to explain financial performance indicators of the 89 business sectors. Hence, special attention has to be paid to identifying and analysing specific factors and assessing the causal link. When established, the set of such factors provides a framework for building of a model to forecast business sector financial indicators.

DISCOVERY OF TIME VARIATION OF THE INTENSITY OF MOLECULAR LINES IN IRC+10216 IN THE SUBMILLIMETER AND FAR-INFRARED DOMAINS

Energy Technology Data Exchange (ETDEWEB)

Cernicharo, J.; Quintana-Lacaci, G.; Agúndez, M.; Velilla-Prieto, L. [Group of Molecular Astrophysics, ICMM, CSIC, C/Sor Juana Inés de La Cruz N3, E-28049 Madrid (Spain); Teyssier, D.; García-Lario, P. [ESA, ESAC, P.O. Box 78, Villanueva de la Cañada, E-28691 Madrid (Spain); Daniel, F. [Univ. Grenoble Alpes, IPAG, F-38000 Grenoble (France); Decin, L. [Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Guélin, M. [Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, F-38406 St-Martin d' Hères (France); Encrenaz, P. [LERMA, Observatoire de Paris, 61 Av. de l' Observatoire, F-75014 Paris (France); De Beck, E. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, SE 439 92 Onsala (Sweden); Barlow, M. J. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Groenewegen, M. A. T. [Koninklijke Sterrenwacht van België, Ringlaan 3, B-1180 Brussels (Belgium); Neufeld, D. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Pearson, J. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2014-11-20

We report on the discovery of strong intensity variations in the high rotational lines of abundant molecular species toward the archetypical circumstellar envelope of IRC+10216. The observations have been carried out with the Heterodyne Instrument for the Far-Infrared (HIFI) instrument on board Herschel and with the IRAM30 m telescope. They cover several observing periods spreading over three years. The line intensity variations for molecules produced in the external layers of the envelope most likely result from time variations in the infrared pumping rates. We analyze the main implications this discovery has on the interpretation of molecular line emission in the envelopes of Mira-type stars. Radiative transfer calculations must take into account both the time variability of infrared pumping and the possible variation of the dust and gas temperatures with stellar phase in order to reproduce the observation of molecular lines at different epochs. The effect of gas temperature variations with stellar phase could be particularly important for lines produced in the innermost regions of the envelope. Each layer of the circumstellar envelope sees the stellar light radiation with a different lag time (phase). Our results show that this effect must be included in the models. The submillimeter and far infrared lines of asymptotic giant branch stars can no longer be considered as safe intensity calibrators.

Activity-Based Costing (ABC and Time-Driven Activity-Based Costing (TDABC: Applicable Methods for University Libraries?

Directory of Open Access Journals (Sweden)

Kate-Riin Kont

2011-01-01

Full Text Available Objective – This article provides an overview of how university libraries research and adapt new cost accounting models, such as “activity-based costing” (ABC and “time-driven activity-based costing” (TDABC, focusing on the strengths and weaknesses of both methods to determine which of these two is suitable for application in university libraries.Methods – This paper reviews and summarizes the literature on cost accounting and costing practices of university libraries. A brief overview of the history of cost accounting, costing, and time and motion studies in libraries is also provided. The ABC and the TDABC method, designed as a revised and easier version of the ABC by Kaplan and Anderson (Kaplan & Anderson 2004 at the beginning of the 21st century, as well as the adoption and adaptation of these methods by university libraries are described, and their strengths and weaknesses, as well as their suitability for university libraries, are analyzed. Results – Cost accounting and costing studies in libraries have a long history, the first of these dating back to 1877. The development of cost accounting and time and motion studies can be seen as a natural evolution of techniques which were created to solve management problems. The ABC method is the best-known management accounting innovation of the last 20 years, and is already widely used in university libraries around the world. However, setting up an ABC system can be very costly, and the system needs to be regularly updated, which further increases its costs. The TDABC system can not only be implemented more quickly (and thus more cheaply, but also can be updated more easily than the traditional ABC, which makes the TDABC the more suitable method for university libraries.Conclusion – Both methods are suitable for university libraries. However, the ABC method can only be implemented in collaboration with an accounting department. The TDABC method can be tested and implemented by

Total variation regularization for a backward time-fractional diffusion problem

International Nuclear Information System (INIS)

Wang, Liyan; Liu, Jijun

2013-01-01

Consider a two-dimensional backward problem for a time-fractional diffusion process, which can be considered as image de-blurring where the blurring process is assumed to be slow diffusion. In order to avoid the over-smoothing effect for object image with edges and to construct a fast reconstruction scheme, the total variation regularizing term and the data residual error in the frequency domain are coupled to construct the cost functional. The well posedness of this optimization problem is studied. The minimizer is sought approximately using the iteration process for a series of optimization problems with Bregman distance as a penalty term. This iteration reconstruction scheme is essentially a new regularizing scheme with coupling parameter in the cost functional and the iteration stopping times as two regularizing parameters. We give the choice strategy for the regularizing parameters in terms of the noise level of measurement data, which yields the optimal error estimate on the iterative solution. The series optimization problems are solved by alternative iteration with explicit exact solution and therefore the amount of computation is much weakened. Numerical implementations are given to support our theoretical analysis on the convergence rate and to show the significant reconstruction improvements. (paper)

Factors affecting variations in time of the remote effects of depression in the surroundings of Thorez opencast mine

Energy Technology Data Exchange (ETDEWEB)

Szilagyi, G.

1976-01-01

Dewatering operations have been carried out in Thorez opencast coal mine since 1960 in order to increase the stability of water-bearing strata and to create safe working conditions. Since that time some 0.1 billion cu.m of water have been drained from underground reservoirs, resulting in the formation of a zone of depression 10 to 15 km in radius. Hydrogeological and technical factors affecting the variations in time of the remote effects of depression are analysed. It is found that the decisive influence is the variation in the volume of accumulated water, and to a lesser extent, the effect of the positioning of the drainage system.

A possibly universal red chromophore for modeling color variations on Jupiter

Science.gov (United States)

Sromovsky, L. A.; Baines, K. H.; Fry, P. M.; Carlson, R. W.

2017-07-01

A new laboratory-generated chemical compound made from photodissociated ammonia (NH3) molecules reacting with acetylene (C2H2) was suggested as a possible coloring agent for Jupiter's Great Red Spot (GRS) by Carlson et al. (2016, Icarus 274, 106-115). Baines et al. (2016, Icarus, submitted) showed that the GRS spectrum measured by the visual channels of the Cassini VIMS instrument in 2000 could be accurately fit by a cloud model in which the chromophore appeared as a physically thin layer of small particles immediately above the main cloud layer of the GRS. Here we show that the same chromophore and same layer location can also provide close matches to the short wavelength spectra of many other cloud features on Jupiter, suggesting this material may be a nearly universal chromophore that could explain the various degrees of red coloration on Jupiter. This is a robust conclusion, even for 12% changes in VIMS calibration and large uncertainties in the refractive index of the main cloud layer due to uncertain fractions of NH4SH and NH3 in its cloud particles. The chromophore layer can account for color variations among north and south equatorial belts, equatorial zone, and the Great Red Spot, by varying particle size from 0.12 μm to 0.29 μm and 1-μm optical depth from 0.06 to 0.76. The total mass of the chromophore layer is much less variable, ranging from 18 to 30 μg/cm2, except in the equatorial zone, where it is only 10-13 μg/cm2. We also found a depression of the ammonia volume mixing ratio in the two belt regions, which averaged 0.4 - 0.5 ×10-4 immediately below the ammonia condensation level, while the other regions averaged twice that value.

Temperature variation in metal ceramic technology analyzed using time domain optical coherence tomography

Science.gov (United States)

Sinescu, Cosmin; Topala, Florin I.; Negrutiu, Meda Lavinia; Duma, Virgil-Florin; Podoleanu, Adrian G.

2014-01-01

The quality of dental prostheses is essential in providing good quality medical services. The metal ceramic technology applied in dentistry implies ceramic sintering inside the dental oven. Every ceramic material requires a special sintering chart which is recommended by the producer. For a regular dental technician it is very difficult to evaluate if the temperature inside the oven remains the same as it is programmed on the sintering chart. Also, maintaining the calibration in time is an issue for the practitioners. Metal ceramic crowns develop a very accurate pattern for the ceramic layers depending on the temperature variation inside the oven where they are processed. Different patterns were identified in the present study for the samples processed with a variation in temperature of +30 °C to +50 °C, respectively - 30 0°C to -50 °C. The OCT imagistic evaluations performed for the normal samples present a uniform spread of the ceramic granulation inside the ceramic materials. For the samples sintered at a higher temperature an alternation between white and darker areas between the enamel and opaque layers appear. For the samples sintered at a lower temperature a decrease in the ceramic granulation from the enamel towards the opaque layer is concluded. The TD-OCT methods can therefore be used efficiently for the detection of the temperature variation due to the ceramic sintering inside the ceramic oven.

Universe: inflation out of chaos

Energy Technology Data Exchange (ETDEWEB)

Linde, A

1985-03-07

The paper reviews the big bang theories of the earliest stages of the evolution of the Universe. The standard model and its associated problems; grand unified theories; scalar fields; and the inflationary Universe scenario; are all described. The newest model - Chaotic inflation, is a variation on the inflationary theme, and is outlined. Applications of this model to some of the standard model problems are discussed.

Agility: A Crucial Capability for Universities in Times of Disruptive Change and Innovation

Science.gov (United States)

Mukerjee, Sheila

2014-01-01

Government funding cuts have provided a new impetus to Australian universities to re-examine their value proposition and corporate focus. While the sector has gone through waves of change in recent times, institutions are now scrambling for their place in a highly competitive market. Institutions explore new revenue opportunities and digital…

Computing Camps for Girls : A First-Time Experience at the University of Limerick

NARCIS (Netherlands)

McInerney, Clare; Lamprecht, A.L.; Margaria, Tiziana

2018-01-01

Increasing the number of females in ICT-related university courses has been a major concern for several years. In 2015, we offered a girls-only computing summer camp for the first time, as a new component in our education and outreach activities to foster students’ interest in our discipline. In

Time variations of fields in superconducting magnets and their effects on accelerators

Energy Technology Data Exchange (ETDEWEB)

Herrup, D.A.; Syphers, M.J.; Johnson, D.E.; Johnson, R.P.; Tollestrup, A.V.; Hanft, R.W.; Brown, B.C.; Lamm, M.J.; Kuchnir, M.; McInturff, A.D.

1988-08-22

A report on the time dependence of magnetic fields in the superconducting magnets of the Fermilab Tevatron has been published. A field variation of order 1 gauss at the aperture radius is observed. Studies on both full sized Tevatron, dipoles and prototype magnets have been used to elucidate these effects. Explanations based on eddy currents in the coil matrix or on flux creep in the superconducting filaments are explored with these tests. Measurement results and techniques for controlling the effect based on new laboratory tests and the latest accelerator operation are presented. 9 refs., 4 figs.

Time variations of fields in superconducting magnets and their effects on accelerators

International Nuclear Information System (INIS)

Herrup, D.A.; Syphers, M.J.; Johnson, D.E.

1988-01-01

A report on the time dependence of magnetic fields in the superconducting magnets of the Fermilab Tevatron has been published. A field variation of order 1 gauss at the aperture radius is observed. Studies on both full sized Tevatron, dipoles and prototype magnets have been used to elucidate these effects. Explanations based on eddy currents in the coil matrix or on flux creep in the superconducting filaments are explored with these tests. Measurement results and techniques for controlling the effect based on new laboratory tests and the latest accelerator operation are presented. 9 refs., 4 figs

Interpretation of engine cycle-to-cycle variation by chaotic time series analysis

Energy Technology Data Exchange (ETDEWEB)

Daw, C.S.; Kahl, W.K.

1990-01-01

In this paper we summarize preliminary results from applying a new mathematical technique -- chaotic time series analysis (CTSA) -- to cylinder pressure data from a spark-ignition (SI) four-stroke engine fueled with both methanol and iso-octane. Our objective is to look for the presence of deterministic chaos'' dynamics in peak pressure variations and to investigate the potential usefulness of CTSA as a diagnostic tool. Our results suggest that sequential peak cylinder pressures exhibit some characteristic features of deterministic chaos and that CTSA can extract previously unrecognized information from such data. 18 refs., 11 figs., 2 tabs.

Study of seasonal variation biochemical parameters of rodents and lagomorphs from the Vivarium of the Faculty of Medicine, University of São Paulo, São Paulo, Brazil

Directory of Open Access Journals (Sweden)

Marilda Osti Spinelli

2014-06-01

Full Text Available ABSTRACT. Spinelli M.O., da Cruz R.J., de Godoy C.M.S.C., Motta M.C. & Damy S.B. [Study of seasonal variation biochemical parameters of rodents and lagomorphs from the Vivarium of the Faculty of Medicine, University of São Paulo, São Paulo, Brazil.] Estudo da variação sazonal dos parâmetros bioquímicos de roedores e lagomorfos do biotério da Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brasil. Revista Brasileira de Medicina Veterinária, 36(2:219-225, 2014. Faculdade de Medicina, Divisão Técnica de Apoio ao Ensino e Pesquisa, Biotério Central, Avenida Doutor Arnaldo, 455, Cerqueira César, São Paulo, SP 01246-903, Brasil. E-mail: marilda@biot.fm.usp.br This work aimed to study the seasonal variation of the biochemical parameters of mice inbred BALB / c and C57BL / 6 mice, rats and rabbits New Zealand, the Vivarium of the Faculty of Medicine, University of Sao Paulo. Which is its clinical significance, assessing the analytes plasma ALT (alanine aminotransferase, AST (aspartate aminotransaminase, urea, urea-BUN (blood urea nitrogen, creatinine, total cholesterol and fractions VLDL (very low density lipoprotein, HDL (high density lipoprotein and LDL (low density lipoprotein? The results showed an increase in concentrations of analytes, statistical significance, especially in summer. The hypotheses that causes nutritional, infectious, water stress or climatic variations did not affect them, suggesting that to assess the health status of colonies of laboratory animals, biochemical parameters must be considered within the range of variation expected for each colony under study.

Relations between Self Regulation, Future Time Perspective and the Delay of Gratification in University Students

Science.gov (United States)

Avci, Suleyman

2013-01-01

The present study was conducted on 508 (331 female, 144 male) first grade university students in order to investigate the relations between self regulation, the future time perspectives, and the delay of gratification in the academic field. A future time perspective scale, an academic delay of gratification scale and a motivational strategies for…

Ethnic variations in lung cancer.

Science.gov (United States)

Groeger, A M; Mueller, M R; Odocha, O; Dekan, G; Salat, A; Röthy, W; Esposito, V; Caputi, M; Wolner, E; Kaiser, H E

1997-01-01

Cancer of the lung is the most frequent cancer in the world, but with wide geographical variation in risk. It is most spread among males of all races worldwide, the only exception being its incidence among Chinese women aged 70 years and older. When comparing the different ethnic groups we have to consider that besides inhaling cigarette smoke actively or as a passive smoker the exposure to occupational carcinogens varies considerably according to different work places. In our study we compared 10 years of data from African-Americans in Howard University Hospital, Washington D.C. with 20 years of data from the white population in the University Hospital of Vienna, Austria. Ethnic patterns are generally consistent within each group in terms of both incidence and mortality. The difference in susceptibility between the sexes, the three major racial groups and already proven differences in genetic variations indicate the difference between individuals concerning the initiation and progression of lung cancer.

Seasonal variation of dystocia in a large Danish cohort.

Science.gov (United States)

Rohr Thomsen, Christine; Uldbjerg, Niels; Hvidman, Lone; Atladóttir, Hjördís Ósk; Henriksen, Tine Brink; Milidou, Ioanna

2014-01-01

Dystocia is one of the most frequent causes of cesarean delivery in nulliparous women. Despite this, its causes are largely unknown. Vitamin D receptor (VDR) has been found in the myometrium. Thus, it is possible that vitamin D affects the contractility of the myometrium and may be involved in the pathogenesis of dystocia. Seasonal variation of dystocia in areas with distinct seasonal variation in sunlight exposure, like Denmark, could imply that vitamin D may play a role. This study examined whether there was seasonal variation in the incidence of dystocia in a Danish population. We used information from a cohort of 34,261 nulliparous women with singleton pregnancies, spontaneous onset of labor between 37 and 42 completed gestational weeks, and vertex fetal presentation. All women gave birth between 1992 and 2010 at the Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby. Logistic regression combined with cubic spline was used to estimate the seasonal variation for each outcome after adjusting for calendar time. No evidence for seasonal variation was found for any of the outcomes: acute cesarean delivery due to dystocia (p = 0.44); instrumental vaginal delivery due to dystocia (p = 0.69); oxytocin augmentation due to dystocia (p = 0.46); and overall dystocia (p = 0.91). No seasonal variation in the incidence of dystocia was observed in a large cohort of Danish women. This may reflect no association between vitamin D and dystocia, or alternatively that other factors with seasonal variation and influence on the occurrence of dystocia attenuate such an association.

Long-time observation of annual variation of Taiwan Strait upwelling in summer season

Science.gov (United States)

Tang, D. L.; Kawamura, H.; Guan, L.

The Taiwan Strait is between Taiwan Island and Mainland China, where several upwelling zones are well known for good fishing grounds. Earlier studies in the strait have been conducted on detecting upwelling by ship measurements with short-term cruises, but long-term variations of upwelling in this region are not understood. The present paper examines satellite images for a long-time observation of two major upwelling zones in the Taiwan Strait: Taiwan Bank Upwelling (TBU) and Dongshan Upwelling (DSU). Sea surface temperature (SST) and chlorophyll a (Chl-a) images have been analyzed for summer months (June, July, and August) from 1980 to 2002. Results reveal annual variation of two upwelling zones. These two upwelling zones occur every year characterized with distinct low water temperature and high Chl-a concentrations. During the period from 1989 to 1998, SST is found to be 1.15 °C lower in TBU, and 1.42 °C lower in the DSU than the Taiwan Strait. The size of DSU has been found to be larger during summer of 1989, 1990, 1993 and 1995; TBU has been found to be weak during summer of 1994 and 1997. Ocean color images obtained from CZCS, OCI, and SeaWiFS also show high Chl-a concentrations (0.8-2.5 mg m-3) in two upwelling zones, which coincide with low SST in terms of location, shape, and time. These high Chl-a concentrations in TBU and DSU may be related to upwelling waters that bring nutrients from bottom to surface. The present results also show the potential of using satellite data for monitoring of ocean environment for long time period.

Genome Variation Map: a data repository of genome variations in BIG Data Center.

Science.gov (United States)

Song, Shuhui; Tian, Dongmei; Li, Cuiping; Tang, Bixia; Dong, Lili; Xiao, Jingfa; Bao, Yiming; Zhao, Wenming; He, Hang; Zhang, Zhang

2018-01-04

The Genome Variation Map (GVM; http://bigd.big.ac.cn/gvm/) is a public data repository of genome variations. As a core resource in the BIG Data Center, Beijing Institute of Genomics, Chinese Academy of Sciences, GVM dedicates to collect, integrate and visualize genome variations for a wide range of species, accepts submissions of different types of genome variations from all over the world and provides free open access to all publicly available data in support of worldwide research activities. Unlike existing related databases, GVM features integration of a large number of genome variations for a broad diversity of species including human, cultivated plants and domesticated animals. Specifically, the current implementation of GVM not only houses a total of ∼4.9 billion variants for 19 species including chicken, dog, goat, human, poplar, rice and tomato, but also incorporates 8669 individual genotypes and 13 262 manually curated high-quality genotype-to-phenotype associations for non-human species. In addition, GVM provides friendly intuitive web interfaces for data submission, browse, search and visualization. Collectively, GVM serves as an important resource for archiving genomic variation data, helpful for better understanding population genetic diversity and deciphering complex mechanisms associated with different phenotypes. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Quantum field theory in flat Robertson-Walker space-time functional Schrodinger picture

International Nuclear Information System (INIS)

Pi, S.Y.

1990-01-01

Quantum field theory in Robertson-Walker space-time is intrinsically time-dependent and the functional Schrodinger picture provides a useful description. This paper discusses free and self-interacting bosonic quantum field theories: Schrodinger picture quantization, time-dependent Gaussian approximations based on variational principles describing time evolution of pure and mixed states, and renormalizability of the Schrodinger picture. The technique introduced can be used to study various dynamical questions in early universe processes

Quantum field theory in flat Robertson-Walker space-time functional Schroedinger picture

International Nuclear Information System (INIS)

Pi, S.Y.

1989-01-01

Quantum field theory in Robertson-Walker space-time is intrinsically time-dependent and the functional Schroedinger picture provides a useful description. We discuss free and self-interacting bosonic quantum field theories: Schroedinger picture quantization, time-dependent Gaussian approximations based on variational principles describing time evolution of pure and mixed states, and renormalizability of the Schroedinger picture. The techniques introduced can be used to study various dynamical questions in early universe processes. (author)

Time variation of the fine structure constant driven by quintessence

International Nuclear Information System (INIS)

Anchordoqui, Luis; Goldberg, Haim

2003-01-01

There are indications from the study of quasar absorption spectra that the fine structure constant α may have been measurably smaller for redshifts z>2. Analyses of other data ( 149 Sm fission rate for the Oklo natural reactor, variation of 187 Re β-decay rate in meteorite studies, atomic clock measurements) which probe variations of α in the more recent past imply much smaller deviations from its present value. In this work we tie the variation of α to the evolution of the quintessence field proposed by Albrecht and Skordis, and show that agreement with all these data, as well as consistency with Wilkinson Microwave Anisotropy Probe observations, can be achieved for a range of parameters. Some definite predictions follow for upcoming space missions searching for violations of the equivalence principle

Variations in the small-scale galactic magnetic field and short time-scale intensity variations of extragalactic radio sources

International Nuclear Information System (INIS)

Simonetti, J.H.

1985-01-01

Structure functions of the Faraday rotation measures (RMs) of extragalactic radio sources are used to investigate variations in the interstellar magnetic field on length scales of approx.0.01 to 100 pc. Model structure functions derived assuming a power-law power spectrum of irregularities in n/sub e/B, are compared with those observed. The results indicate an outer angular scale for RM variations of approximately less than or equal to 5 0 and evidence for RM variations on scales as small as 1'. Differences in the variance of n/sub e/B fluctuations for various lines of sight through the Galaxy are found. Comparison of pulsar scintillations in right- and left-circular polarizations yield an upper limit to the variations in n/sub e/ on a length scale of approx.10 11 cm. RMs were determined through high-velocity molecular flows in galactic star-formation regions, with the goal of constraining magnetic fields in and near the flows. RMs of 7 extragalactic sources with a approx.20 arcmin wide area seen through Cep A, fall in two groups separated by approx.150 rad m -2 - large given our knowledge of RM variations on small angular scales and possibly a result of the anisotropy of the high-velocity material

Superluminal Kinematics in the Milne Universe Causality in the Cosmic Time Order

CERN Document Server

Tomaschitz, R

2000-01-01

The causality of superluminal signal transfer in the galaxy background is scrutinized. The cosmic time of the comoving galaxy frame determines a distinguished time order for events connected by superluminal signals. Every observer can relate his rest frame to the galaxy frame, and compare so the time order of events in his proper time to the cosmic time order. In this way all observers arrive at identical conclusions on the causality of events connected by superluminal signals. The energy of tachyons (superluminal particles) is defined in the comoving galaxy frame analogous to the energy of subluminal particles. It is positive in the galaxy frame and bounded from below in the rest frames of geodesically moving observers, so that particle-tachyon interactions can be based on energy-momentum conservation. We study tachyons in a Robertson-Walker cosmology with linear expansion factor and open, negatively curved 3-space (Milne universe). This cosmology admits globally geodesic rest frames for uniformly moving obs...

CLASP/SJ Observations of Rapid Time Variations in the Ly α Emission in a Solar Active Region

Energy Technology Data Exchange (ETDEWEB)

Ishikawa, Shin-nosuke [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252–5210 (Japan); Kubo, Masahito; Katsukawa, Yukio; Kano, Ryouhei; Narukage, Noriyuki; Ishikawa, Ryohko; Bando, Takamasa [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Winebarger, Amy; Kobayashi, Ken [NASA Marshall Space Flight Center, Huntsville, AL 35812 (United States); Trujillo Bueno, Javier [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain); Auchère, Frédéric, E-mail: s.ishikawa@solar.isas.jaxa.jp [Institut d’Astrophysique Spatiale, CNRS/Univ. Paris-Sud 11, Bätiment 121, F-91405 Orsay (France)

2017-09-10

The Chromospheric Ly α SpectroPolarimeter (CLASP) is a sounding rocket experiment launched on 2015 September 3 to investigate the solar chromosphere and transition region. The slit-jaw (SJ) optical system captured Ly α images with a high time cadence of 0.6 s. From the CLASP/SJ observations, many variations in the solar chromosphere and transition region emission with a timescale of <1 minute were discovered. In this paper, we focus on the active region within the SJ field of view and investigate the relationship between short (<30 s) temporal variations in the Ly α emission and the coronal structures observed by Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA). We compare the Ly α temporal variations at the coronal loop footpoints observed in the AIA 211 Å (≈2 MK) and AIA 171 Å (≈0.6 MK) channels with those in the regions with bright Ly α features without a clear association with the coronal loop footpoints. We find more short (<30 s) temporal variations in the Ly α intensity in the footpoint regions. Those variations did not depend on the temperature of the coronal loops. Therefore, the temporal variations in the Ly α intensity at this timescale range could be related to the heating of the coronal structures up to temperatures around the sensitivity peak of 171 Å. No signature was found to support the scenario that these Ly α intensity variations were related to the nanoflares. Waves or jets from the lower layers (lower chromosphere or photosphere) are possible causes for this phenomenon.

Natural time analysis on the ultra-low frequency magnetic field variations prior to the 2016 Kumamoto (Japan) earthquakes

Science.gov (United States)

Potirakis, Stelios M.; Schekotov, Alexander; Asano, Tomokazu; Hayakawa, Masashi

2018-04-01

On 15 April 2016 a very strong and shallow earthquake (EQ) (MW = 7.0 , depth ∼ 10 km) occurred in Southwest Japan under the city of Kumamoto, while two very strong foreshocks (MW = 6.2 and MW = 6.0) preceded by about one day. The Kumamoto EQs being very catastrophic, have already attracted much attention among the scientific community in a quest for understanding the generation mechanism, as well as for reporting any preseismic anomalies in various observables and assessing the effectivity of the current early warning systems. In the present article we report precursory behavior of the ground-based observed ultra-low frequency (ULF) magnetic field variations before the Kumamoto EQs. By analyzing specific ULF magnetic field characteristics in terms of the recently introduced natural time (NT) analysis method, we identified that ULF magnetic field variations presented critical features from 2 weeks up to 1 month before the Kumamoto EQs. Specifically, the ULF magnetic field characteristics Fh , Fz , Dh and δDep were analyzed. The first two represent variations of the horizontal and vertical components of the geomagnetic field. The third and fourth characteristics correspond to the depression (decrease) and a relative depression of the horizontal magnetic field variations, respectively. The latter depends on the degree of ionospheric disturbance. All of them were found to reach criticality before the Kumamoto EQs; however, in different time periods for each characteristic.

Gravity Variations Related to Earthquakes in the BTTZ Region in China

Science.gov (United States)

Zheng, J.; Liu, K.; Lu, H.; Liu, D.; Chen, Y.; Kuo, J. T.

2006-05-01

Temporal variations of gravity before and after earthquakes have been observed since 1960s, but a definitive conclusion has not been reached concerning the relationship between the gravity variation and earthquake occurrence. Since 1980, the first US/China joint scientific research project has been monitoring micro-gravity variations related to earthquakes in the Beijing-Tianjin-Tangshan-Zhangjiekou (BTTZ) region in China through the establishment of a network of spatially and temporally continuous and discrete gravity stations. With the data of both temporally continuous and discrete data of gravity variations accumulated and analyzed, a general picture of gravity variation associated with the seismogenesis and occurrence of earthquakes in the BTTZ region has been emerged clearly. Some of the major findings are 1. Gravity variations before and after earthquakes exist spatially and temporally; 2. Gravity variation data of temporally continuous measurements are essential to monitor the variations of gravity related to earthquakes unless temporally discrete gravity data are made in very close time intervals. 3. Concept of epicentroid and hypocentroid with respect to the maximum values of gravity variation is valid and has been experimentally verified; 4. The gravity variations related to the occurrence of earthquakes in the BTTZ region for the magnitudes of 4-5 earthquakes support the proposed "combined dilatation model", i.e., a dual-dilatancy of diffusion dilatancy (D/D) and the fault zone dilatancy (FZD) models; 5. Although the temporally discrete gravity variation data were collected in a larger time interval of about six months in the BTTZ region, these gravity variation data, in some cases, indicate that these variations are related to the occurrence of earthquakes; 7. Subsurface fluids do play a very important role in the gravity variations that have not been recognized and emphasized previously; 7. With the temporally continuous gravity variation data, the

Time-Dependent Variations in Structure of Sheep Wool Irradiated by Electron Beam

Directory of Open Access Journals (Sweden)

Zuzana Hanzlíková

2017-01-01

Full Text Available Wool scoured in tap water with no special degreasing and containing a balanced humidity responding to usual laboratory conditions was irradiated by accelerated electron beam in the range of 0–350 kGy dose. Time variations of the wool structure were measured using FTIR, Raman, and EPR spectroscopy. The aim was to determine whether preexposure treatment of the wool, as well as postexposure time, affects the properties of the irradiated wool. Reactive products such as S-sulfonate, cystine monoxide, cystine dioxide, cysteic acid, disulphides, and carboxylates displayed a considerable fluctuation in quantity depending on both the absorbed dose and time. Mutual transformations of S-oxidized products into cysteic acid appeared to be faster than those in dry and degreased wool assuming that the present humidity inside the fibres is decisive as an oxygen source. EPR results indicated a longer lifetime for free radicals induced by lower doses compared with the radicals generated by higher ones. The pattern of the conformational composition of the secondary structure (α-helix, β-sheet, random, and residual conformations also showed a large variability depending on absorbed dose as well as postexposure time. The most stable secondary structure was observed in nonirradiated wool but even this showed a small but observable change after a longer time, too.

Survey Shows Variation in Ph.D. Methods Training.

Science.gov (United States)

Steeves, Leslie; And Others

1983-01-01

Reports on a 1982 survey of journalism graduate studies indicating considerable variation in research methods requirements and emphases in 23 universities offering doctoral degrees in mass communication. (HOD)

Gender Variations in the Effects of Number of Organizational Memberships, Number of Social Networking Sites, and Grade-Point Average on Global Social Responsibility in Filipino University Students

Directory of Open Access Journals (Sweden)

Romeo B. Lee

2016-02-01

Full Text Available The study seeks to estimate gender variations in the direct effects of (a number of organizational memberships, (b number of social networking sites (SNS, and (c grade-point average (GPA on global social responsibility (GSR; and in the indirect effects of (a and of (b through (c on GSR. Cross-sectional survey data were drawn from questionnaire interviews involving 3,173 Filipino university students. Based on a path model, the three factors were tested to determine their inter-relationships and their relationships with GSR. The direct and total effects of the exogenous factors on the dependent variable are statistically significantly robust. The indirect effects of organizational memberships on GSR through GPA are also statistically significant, but the indirect effects of SNS on GSR through GPA are marginal. Men and women significantly differ only in terms of the total effects of their organizational memberships on GSR. The lack of broad gender variations in the effects of SNS, organizational memberships and GPA on GSR may be linked to the relatively homogenous characteristics and experiences of the university students interviewed. There is a need for more path models to better understand the predictors of GSR in local students.

Gender Variations in the Effects of Number of Organizational Memberships, Number of Social Networking Sites, and Grade-Point Average on Global Social Responsibility in Filipino University Students

Science.gov (United States)

Lee, Romeo B.; Baring, Rito V.; Sta. Maria, Madelene A.

2016-01-01

The study seeks to estimate gender variations in the direct effects of (a) number of organizational memberships, (b) number of social networking sites (SNS), and (c) grade-point average (GPA) on global social responsibility (GSR); and in the indirect effects of (a) and of (b) through (c) on GSR. Cross-sectional survey data were drawn from questionnaire interviews involving 3,173 Filipino university students. Based on a path model, the three factors were tested to determine their inter-relationships and their relationships with GSR. The direct and total effects of the exogenous factors on the dependent variable are statistically significantly robust. The indirect effects of organizational memberships on GSR through GPA are also statistically significant, but the indirect effects of SNS on GSR through GPA are marginal. Men and women significantly differ only in terms of the total effects of their organizational memberships on GSR. The lack of broad gender variations in the effects of SNS, organizational memberships and GPA on GSR may be linked to the relatively homogenous characteristics and experiences of the university students interviewed. There is a need for more path models to better understand the predictors of GSR in local students. PMID:27247700

Gender Variations in the Effects of Number of Organizational Memberships, Number of Social Networking Sites, and Grade-Point Average on Global Social Responsibility in Filipino University Students.

Science.gov (United States)

Lee, Romeo B; Baring, Rito V; Sta Maria, Madelene A

2016-02-01

The study seeks to estimate gender variations in the direct effects of (a) number of organizational memberships, (b) number of social networking sites (SNS), and (c) grade-point average (GPA) on global social responsibility (GSR); and in the indirect effects of (a) and of (b) through (c) on GSR. Cross-sectional survey data were drawn from questionnaire interviews involving 3,173 Filipino university students. Based on a path model, the three factors were tested to determine their inter-relationships and their relationships with GSR. The direct and total effects of the exogenous factors on the dependent variable are statistically significantly robust. The indirect effects of organizational memberships on GSR through GPA are also statistically significant, but the indirect effects of SNS on GSR through GPA are marginal. Men and women significantly differ only in terms of the total effects of their organizational memberships on GSR. The lack of broad gender variations in the effects of SNS, organizational memberships and GPA on GSR may be linked to the relatively homogenous characteristics and experiences of the university students interviewed. There is a need for more path models to better understand the predictors of GSR in local students.

Variational extension of the time-dependent mean field approach

International Nuclear Information System (INIS)

Flocard, H.

1989-01-01

We investigate an application of the variational principle of Balian and Veneroni for density operators and observables. Our choice for the trial spaces incorporates correlations in the density operator. It allows one to calculate the expectation values of both one-body and two-body observables. We derive a set of coupled equations which extends the TDHF formalism, and determines the evolution of the partition function, the one-body density and the second cumulant (it corresponds also to a truncation of the quantal counterpart of the BBKGY equations). By restricting further the trial space for the two-body observables, the variational principle generates simpler equations which still include the effects of a selected class of correlations on the evolution of the one-body density

Quantum variational calculus

CERN Document Server

Malinowska, Agnieszka B

2014-01-01

This Brief puts together two subjects, quantum and variational calculi by considering variational problems involving Hahn quantum operators. The main advantage of its results is that they are able to deal with nondifferentiable (even discontinuous) functions, which are important in applications. Possible applications in economics are discussed. Economists model time as continuous or discrete. Although individual economic decisions are generally made at discrete time intervals, they may well be less than perfectly synchronized in ways discrete models postulate. On the other hand, the usual assumption that economic activity takes place continuously, is nothing else than a convenient abstraction that in many applications is far from reality. The Hahn quantum calculus helps to bridge the gap between the two families of models: continuous and discrete. Quantum Variational Calculus is self-contained and unified in presentation. It provides an opportunity for an introduction to the quantum calculus of variations fo...

Fixed point theory, variational analysis, and optimization

CERN Document Server

Al-Mezel, Saleh Abdullah R; Ansari, Qamrul Hasan

2015-01-01

""There is a real need for this book. It is useful for people who work in areas of nonlinear analysis, optimization theory, variational inequalities, and mathematical economics.""-Nan-Jing Huang, Sichuan University, Chengdu, People's Republic of China

Menstrual variation of breast volume and T{sub 2} relaxation times in cyclical mastalgia

Energy Technology Data Exchange (ETDEWEB)

Hussain, Zainab [Department of Medical Imaging, University of Liverpool, Johnstone Building, Brownlow Hill, P.O. Box 147, Liverpool, Merseyside L69 3GB (United Kingdom); Magnetic Resonance and Image Analysis Research Centre, University of Liverpool, Johnstone Building, Brownlow Hill, P.O. Box 147, Liverpool, Merseyside L69 3GB (United Kingdom)], E-mail: zay@liverpool.ac.uk; Brooks, Jonathan [Magnetic Resonance and Image Analysis Research Centre, University of Liverpool, Johnstone Building, Brownlow Hill, P.O. Box 147, Liverpool, Merseyside L69 3GB (United Kingdom); Department of Human Anatomy and Genetics, University of Oxford, Oxford (United Kingdom); Percy, Dave [Centre for Operational Research and Applied Statistics, University of Salford, Salford, Greater Manchester M5 4WT (United Kingdom)

2008-02-15

Purpose: Hormonal activity causes breast volume to change during the menstrual cycle. One possible cause of this volume change is thought to be due to water retention or oedema within the tissues. We used magnetic resonance imaging (MRI) to study the variation in breast volume and {sup 1}H Magnetic Resonance Spectroscopy (MRS) to measure T{sub 2} relaxation times which are known to increase with increasing tissue water content. We hypothesised that an increase in breast volume will elevate T{sub 2} relaxation due to the presence of an increased water content within the breast. T{sub 2} Relaxation time and volume were studied in fifteen control subjects and in a cohort of eight patients with cyclical mastalgia in order to determine whether changes in breast volume and T{sub 2} relaxation times differed in controls and patients during menses, ovulation and premenses. Method: Breast volume was determined by the Cavalieri method in combination with point counting techniques on MR images and T{sub 2} relaxation times of the water and fat in a voxel of breast tissue were obtained using {sup 1}H Magnetic Resonance Spectroscopy (MRS). Results: Statistical analysis (ANOVA) demonstrated highly significant differences in breast volume between the three stages of the cycle (p < 0.0005) with breast volume being greatest premenstrually. Patients did not exhibit an increase in volume premenstrually, significantly above controls. T{sub 2} of fat or water did not depend on stage of cycle. T-tests demonstrated no significant differences in T{sub 2} of water or fat between patient and control groups. The average T{sub 2} relaxation time of water was lowest in the patient and control groups during ovulation and highest in the patient group during premenses. Conclusion: We have performed the first combined volumetric and spectroscopic study of women with cyclical mastalgia and demonstrated that the global changes in volumes and T{sub 2} were not significantly different from normal

Effect of Reduced Phosphoric Acid Pre-etching Times 
on Enamel Surface Characteristics and Shear Fatigue Strength Using Universal Adhesives.

Science.gov (United States)

Tsujimoto, Akimasa; Fischer, Nicholas; Barkmeier, Wayne; Baruth, Andrew; Takamizawa, Toshiki; Latta, Mark; Miyazaki, Masashi

2017-01-01

To examine the effect of reduced phosphoric acid pre-etching times on enamel fatigue bond strength of universal adhesives and surface characteristics by using atomic force microscopy (AFM). Three universal adhesives were used in this study (Clearfil Universal Bond [C], G-Premio Bond [GP], Scotchbond Universal Adhesive [SU]). Four pre-etching groups were employed: enamel pre-etched with phosphoric acid and immediately rinsed with an air-water spray, and enamel pre-etched with phosphoric acid for 5, 10, or 15 s. Ground enamel was used as the control group. For the initial bond strength test, 15 specimens per etching group for each adhesive were used. For the shear fatigue test, 20 specimens per etching group for each adhesive were loaded using a sine wave at a frequency of 20 Hz for 50,000 cycles or until failure occurred. Initial shear bond strengths and fatigue shear strengths of composite adhesively bonded to ground and pre-etched enamel were determined. AFM observations of ground and pre-etched enamel were also conducted, and surface roughness as well as surface area were evaluated. The initial shear bond strengths and fatigue shear strengths of the universal adhesives in the pre-etched groups were significantly higher than those of the control group, and were not influenced by the pre-etching time. Significantly higher surface roughness and surface area of enamel surfaces in pre-etched groups were observed compared with those in the control group. While the surface area was not significantly influenced by etching time, surface roughness of the enamel surfaces in the pre-etched groups significantly increased with pre-etching time. The results of this in vitro study suggest that reduced phosphoric acid pre-etching times do not impair the fatigue bond strength of universal adhesives. Although fatigue bond strength and surface area were not influenced by phosphoric-acid etching times, surface roughness increased with increasing etching time.

Time-wise variation of scouring at bridge abutments

Indian Academy of Sciences (India)

provides useful information for the degree of scour counter-measure to be imple- mented against ..... the extension of the area of protection as well as the size, layer thickness, and surface elevation .... 275, School of Engineering, University of.

Time reborn from the crisis in physics to the future of the universe

CERN Document Server

Smolin, Lee

2013-01-01

One of our foremost thinkers and public intellectuals offers a radical new view of the nature of time and the cosmos. The fact that time is real may seem obvious. You experience it passing every day when you watch clocks tick, bread toast, and children grow. But most physicists see things differently, from Newton to Einstein to today’s quantum theorists. For them, time isn’t real. You may think you experience time passing, but they say it’s just an illusion. Lee Smolin, author of the controversial bestseller The Trouble with Physics, argues this limited notion of time is holding physics back. It’s time for a major revolution in scientific thought. The reality of time could be the key to the next big breakthrough in theoretical physics. What if the laws of physics themselves were not timeless? What if they could evolve? Time Reborn offers a radical new approach to cosmology that embraces the reality of time and opens up a whole new universe of possibilties. There are few ideas that, like our noti...

Parallel algorithm of real-time infrared image restoration based on total variation theory

Science.gov (United States)

Zhu, Ran; Li, Miao; Long, Yunli; Zeng, Yaoyuan; An, Wei

2015-10-01

Image restoration is a necessary preprocessing step for infrared remote sensing applications. Traditional methods allow us to remove the noise but penalize too much the gradients corresponding to edges. Image restoration techniques based on variational approaches can solve this over-smoothing problem for the merits of their well-defined mathematical modeling of the restore procedure. The total variation (TV) of infrared image is introduced as a L1 regularization term added to the objective energy functional. It converts the restoration process to an optimization problem of functional involving a fidelity term to the image data plus a regularization term. Infrared image restoration technology with TV-L1 model exploits the remote sensing data obtained sufficiently and preserves information at edges caused by clouds. Numerical implementation algorithm is presented in detail. Analysis indicates that the structure of this algorithm can be easily implemented in parallelization. Therefore a parallel implementation of the TV-L1 filter based on multicore architecture with shared memory is proposed for infrared real-time remote sensing systems. Massive computation of image data is performed in parallel by cooperating threads running simultaneously on multiple cores. Several groups of synthetic infrared image data are used to validate the feasibility and effectiveness of the proposed parallel algorithm. Quantitative analysis of measuring the restored image quality compared to input image is presented. Experiment results show that the TV-L1 filter can restore the varying background image reasonably, and that its performance can achieve the requirement of real-time image processing.

Annual and inter-annual variations of 6.5-day-planetary-waves in MLT observed by TIMED/SABER

Science.gov (United States)

Huang, Yingying; Li, Huijun; Li, Chongyin; Zhang, Shaodong

2017-04-01

Annual and inter-annual variations of 6.5DWs in 20-110 km, 52°S-52°N, 2002-2016 are studied by using v2.0 TIMED/SABER kinetic temperature data. Firstly, global annual variations of 6.5DW's spectral power and amplitudes are obtained. Strong wave amplitudes emerge in 30°S/N-50°S/N, and peaks in altitude separate in stratosphere (40-50 km), mesosphere (80-90 km) and the lower thermosphere (100-110 km), respectively. Their annual variations are similar in both hemispheres, but different in altitude. In 40-50 km, the annual maximums emerge mostly in winters: Dec.-Jan. in the NH and Jul.-Aug. in the SH. In MLT, annual peaks arise twice in each half of year. In 80-90 km, they're mainly in equinoctial seasons and winters: May, Aug.-Sep. and Jan. in the NH and Feb., Nov. and May in the SH. In 100-110 km, they emerge mainly in equinoctial seasons: Apr.-May and Aug.-Sep. in the NH and Feb.-Mar. and Oct.-Nov. in the SH. Then, inter-annual variations of 6.5DW amplitudes during the 14-year period are studied. Frequency spectra of monthly-mean amplitudes show that, main dynamics in long-term variations of 6.5DWs are AO and SAO in both hemispheres. Besides, QBO are visible in both hemispheres and 4-month period signals are noticed in the NH in MLT. Amplitudes of SAO, AO and QBO are obtained by bandpass filter. Their amplitudes are comparable in stratosphere and mesosphere, and QBO signals are weaker than the others in the LT. Vertical variations both of SAO and AO amplitudes are very stable. AO structures have little inter-annual changes, while inter-annual variations of SAO are significant and are related with 6.5DW. It means that annual and inter-annual variations of 6.5DW are mainly controlled by AO and SAO, respectively. Although QBO signals are weaker and their variations are less regular than AO and SAO, their phases seems to relate with inter-annual variations of 6.5DW as well.

The Main Reciprocal for Teaching Load: Faculty Use of Research Time.

Science.gov (United States)

Colbeck, Carol L.

This study examined the allocation of time college faculty give to various research tasks. Case studies were conducted of 12 faculty members in four departments selected for variation by university type (research and comprehensive) and discipline (Physics and English). The work of each faculty member was observed on five non-consecutive days for a…

HGVA: the Human Genome Variation Archive.

Science.gov (United States)

Lopez, Javier; Coll, Jacobo; Haimel, Matthias; Kandasamy, Swaathi; Tarraga, Joaquin; Furio-Tari, Pedro; Bari, Wasim; Bleda, Marta; Rueda, Antonio; Gräf, Stefan; Rendon, Augusto; Dopazo, Joaquin; Medina, Ignacio

2017-07-03

High-profile genomic variation projects like the 1000 Genomes project or the Exome Aggregation Consortium, are generating a wealth of human genomic variation knowledge which can be used as an essential reference for identifying disease-causing genotypes. However, accessing these data, contrasting the various studies and integrating those data in downstream analyses remains cumbersome. The Human Genome Variation Archive (HGVA) tackles these challenges and facilitates access to genomic data for key reference projects in a clean, fast and integrated fashion. HGVA provides an efficient and intuitive web-interface for easy data mining, a comprehensive RESTful API and client libraries in Python, Java and JavaScript for fast programmatic access to its knowledge base. HGVA calculates population frequencies for these projects and enriches their data with variant annotation provided by CellBase, a rich and fast annotation solution. HGVA serves as a proof-of-concept of the genome analysis developments being carried out by the University of Cambridge together with UK's 100 000 genomes project and the National Institute for Health Research BioResource Rare-Diseases, in particular, deploying open-source for Computational Biology (OpenCB) software platform for storing and analyzing massive genomic datasets. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Assessment of the Variation Associated with Repeated Measurement of Gastrointestinal Transit Times and Assessment of the Effect of Oral Ranitidine on Gastrointestinal Transit Times Using a Wireless Motility Capsule System in Dogs

Directory of Open Access Journals (Sweden)

Jonathan A. Lidbury

2012-01-01

Full Text Available This study aimed to evaluate the variation associated with repeated measurement of gastrointestinal (GI transit times and the effect of oral ranitidine on GI transit times in healthy dogs using a wireless motility capsule (WMC system. Eight privately owned healthy adult dogs were enrolled, and one developed diarrhea and was removed from the study. For the first 3 repetitions, each dog was fed a standard meal followed by oral administration of a WMC. For the 4th repetition, each dog was given ranitidine hydrochloride (75 mg PO every 12 hours prior to and during assessment of GI transit times. Mean between-subject coefficients of variation for gastric emptying time (GET, small and large bowel transit time (SLBTT, and total transit time (TTT were 26.9%, 32.3%, and 19.6%, respectively. Mean within-subject coefficients of variation for GET, SLBTT, and TTT were 9.3%, 19.6%, and 15.9%, respectively. Median GET, SLBTT, and TTT without ranitidine were 719, 1,636, and 2,735 minutes, respectively. Median GET, SLBTT, and TTT with ranitidine were 757, 1,227, and 2,083 minutes, respectively. No significant differences in GI transit times were found between any of the 4 repetitions. Under these experimental conditions, no significant effects of oral ranitidine on GI transit times were observed.

Normal variation of hepatic artery

International Nuclear Information System (INIS)

Kim, Inn; Nam, Myung Hyun; Rhim, Hyun Chul; Koh, Byung Hee; Seo, Heung Suk; Kim, Soon Yong

1987-01-01

This study was an analyses of blood supply of the liver in 125 patients who received hepatic arteriography and abdominal aortography from Jan. 1984 to Dec. 1986 at the Department of Radiology of Hanyang University Hospital. A. Variations in extrahepatic arteries: 1. The normal extrahepatic artery pattern occurred in 106 of 125 cases (84.8%) ; Right hepatic and left hepatic arteries arising from the hepatic artery proper and hepatic artery proper arising from the common hepatic artery. 2. The most common type of variation of extrahepatic artery was replaced right hepatic artery from superior mesenteric artery: 6 of 125 cases (4.8%). B. Variations in intrahepatic arteries: 1. The normal intrahepatic artery pattern occurred in 83 of 125 cases (66.4%). Right hepatic and left hepatic arteries arising from the hepatic artery proper and middle hepatic artery arising from lower portion of the umbilical point of left hepatic artery. 2. The most common variation of intrahepatic arteries was middle hepatic artery. 3. Among the variation of middle hepatic artery; Right, middle and left hepatic arteries arising from the same location at the hepatic artery proper was the most common type; 17 of 125 cases (13.6%)

Time variation in European carbon pass-through rates in electricity futures prices

International Nuclear Information System (INIS)

Huisman, Ronald; Kiliç, Mehtap

2015-01-01

The European Union Emissions Trading Scheme is a means to price emission allowances. Electricity market prices should reflect these market prices of emission allowances as they are a cost factor for power producers. The pass-through rate is the fraction of the emission allowance price that is passed through to electricity market prices. It is often measured and presented as an average or a fixed estimate over some time period. However, we expect that the pass-through rates should actually vary over time as electricity supply curves reflect the marginal costs of different producers that differ in emission intensity. We apply a Kalman Filter approach to observe pass-through rates in Germany and U.K. and find strong support for time varying instead of fixed pass-through rates. Although policy makers are interested in the impact of a policy on average, our results indicate that one needs to be careful with the time-frame over which pass-through rates are measured for policy evaluation, as an incorrect chosen evaluation period could cause an under- or overestimation of the pass-through rate. In addition, our model helps to provide policy makers with insight in the development of pass-through rates when market circumstances change with respect to power production. - Highlights: • We analyse the time-variation of the emission pass-through rate in power prices. • We examine historical futures prices for Germany and the U.K. • We test the hypothesis by using the Kalman Filter methodology. • Strong support is found that pass-through rates vary over time. • The chosen time-frame for pass-through rates is important for policy evaluation.

Simplified Real-Time Multiplex Detection of Loop-Mediated Isothermal Amplification Using Novel Mediator Displacement Probes with Universal Reporters.

Science.gov (United States)

Becherer, Lisa; Bakheit, Mohammed; Frischmann, Sieghard; Stinco, Silvina; Borst, Nadine; Zengerle, Roland; von Stetten, Felix

2018-04-03

A variety of real-time detection techniques for loop-mediated isothermal amplification (LAMP) based on the change in fluorescence intensity during DNA amplification enable simultaneous detection of multiple targets. However, these techniques depend on fluorogenic probes containing target-specific sequences. That complicates the adaption to different targets leading to time-consuming assay optimization. Here, we present the first universal real-time detection technique for multiplex LAMP. The novel approach allows simple assay design and is easy to implement for various targets. The innovation features a mediator displacement probe and a universal reporter. During amplification of target DNA the mediator is displaced from the mediator displacement probe. Then it hybridizes to the reporter generating a fluorescence signal. The novel mediator displacement (MD) detection was validated against state-of-the-art molecular beacon (MB) detection by means of a HIV-1 RT-LAMP: MD surpassed MB detection by accelerated probe design (MD: 10 min, MB: 3-4 h), shorter times to positive (MD 4.1 ± 0.1 min shorter than MB, n = 36), improved signal-to-noise fluorescence ratio (MD: 5.9 ± 0.4, MB: 2.7 ± 0.4; n = 15), and showed equally good or better analytical performance parameters. The usability of one universal mediator-reporter set in different multiplex assays was successfully demonstrated for a biplex RT-LAMP of HIV-1 and HTLV-1 and a biplex LAMP of Haemophilus ducreyi and Treponema pallidum, both showing good correlation between target concentration and time to positive. Due to its simple implementation it is suggested to extend the use of the universal mediator-reporter sets to the detection of various other diagnostic panels.

A technique to detect periodic and non-periodic ultra-rapid flux time variations with standard radio-astronomical data

Science.gov (United States)

Borra, Ermanno F.; Romney, Jonathan D.; Trottier, Eric

2018-06-01

We demonstrate that extremely rapid and weak periodic and non-periodic signals can easily be detected by using the autocorrelation of intensity as a function of time. We use standard radio-astronomical observations that have artificial periodic and non-periodic signals generated by the electronics of terrestrial origin. The autocorrelation detects weak signals that have small amplitudes because it averages over long integration times. Another advantage is that it allows a direct visualization of the shape of the signals, while it is difficult to see the shape with a Fourier transform. Although Fourier transforms can also detect periodic signals, a novelty of this work is that we demonstrate another major advantage of the autocorrelation, that it can detect non-periodic signals while the Fourier transform cannot. Another major novelty of our work is that we use electric fields taken in a standard format with standard instrumentation at a radio observatory and therefore no specialized instrumentation is needed. Because the electric fields are sampled every 15.625 ns, they therefore allow detection of very rapid time variations. Notwithstanding the long integration times, the autocorrelation detects very rapid intensity variations as a function of time. The autocorrelation could also detect messages from Extraterrestrial Intelligence as non-periodic signals.

Primordial inhomogeneities in the expanding universe. II - General features of spherical models at late times

Science.gov (United States)

Olson, D. W.; Silk, J.

1979-01-01

This paper studies the density profile that forms around a spherically symmetric bound central core immersed in a homogeneous-background k = 0 or k = -1 Friedmann-Robertson-Walker cosmological model, with zero pressure. Although the density profile in the linearized regime is almost arbitrary, in the nonlinear regime certain universal features of the density profile are obtained that are independent of the details of the initial conditions. The formation of 'halos' ('holes') with densities greater than (less than) the average cosmological density is discussed. It is shown that in most regions 'halos' form, and universal values are obtained for the slope of the ln (density)-ln (radius) profile in those 'halos' at late times, independently of the shape of the initial density profile. Restrictions are derived on where it is possible for 'holes' to exist at late times and on how such 'holes' must have evolved.

Individual variation in habituation: behaviour over time toward different stimuli in threespine sticklebacks (Gasterosteus aculeatus)

Science.gov (United States)

Bell, Alison M.; Peeke, Harman V.S.

2014-01-01

Habituation, or the relatively permanent waning of a response as a result of repeated stimulation, is a form of behavioural plasticity that allows animals to filter out irrelevant stimuli and to focus selectively on important stimuli. Individuals that fail to habituate might be at a disadvantage if they continue to respond to irrelevant stimuli; therefore, habituation can have adaptive significance. In this study we compared rates of behaviour over time toward three different ecologically-relevant stimuli (food, a male intruder and a gravid female) in threespine sticklebacks (Gasterosteus aculeatus). We detected evidence for habituation to the stimuli, and males in this study were especially aggressive toward both male and female conspecifics. Although there were some clear temporal patterns that could be detected by looking at average behaviour, not all individuals behaved in the same ‘average’ way. We detected substantial inter-individual variation in behaviour toward all three stimuli, inter-individual variation in rates of habituation to both male and female conspecifics, but no evidence for correlations between behaviours across stimuli (behavioural syndromes). These results suggest that individual animals vary in rates of habituation, and prompt hypotheses about the causes and consequences of variation in rates of habituation. PMID:25678715

Characterization of indoor aerosol temporal variations for the real-time management of indoor air quality

Science.gov (United States)

Ciuzas, Darius; Prasauskas, Tadas; Krugly, Edvinas; Sidaraviciute, Ruta; Jurelionis, Andrius; Seduikyte, Lina; Kauneliene, Violeta; Wierzbicka, Aneta; Martuzevicius, Dainius

2015-10-01

The study presents the characterization of dynamic patterns of indoor particulate matter (PM) during various pollution episodes for real-time IAQ management. The variation of PM concentrations was assessed for 20 indoor activities, including cooking related sources, other thermal sources, personal care and household products. The pollution episodes were modelled in full-scale test chamber representing a standard usual living room with the forced ventilation of 0.5 h-1. In most of the pollution episodes, the maximum concentration of particles in exhaust air was reached within a few minutes. The most rapid increase in particle concentration was during thermal source episodes such as candle, cigarette, incense stick burning and cooking related sources, while the slowest decay of concentrations was associated with sources, emitting ultrafine particle precursors, such as furniture polisher spraying, floor wet mopping with detergent etc. Placement of the particle sensors in the ventilation exhaust vs. in the centre of the ceiling yielded comparable results for both measured maximum concentrations and temporal variations, indicating that both locations were suitable for the placement of sensors for the management of IAQ. The obtained data provides information that may be utilized considering measurements of aerosol particles as indicators for the real-time management of IAQ.

Comparative analysis of long-time variations of multicomponent ion ring current according to data of geostationary Gorizont satellite

International Nuclear Information System (INIS)

Kovtyukh, A.S.; Panasyuk, M.I.; Vlasova, N.A.; Sosnovets, Eh.N.

1990-01-01

Long-time variations of the fluxes of the H + , [N,O] 2+ and [C,N,O] 6 6 + ions with energy E/Q∼60-120 keV/e measured by the GORIZONT (1985-07A) satellite in the geostationary orbit at noon time are analyzed. The results are dsicussed and are compared with current models of the formation of the Earth's ion ring current

Inter-fraction bladder filling variations and time trends for cervical cancer patients assessed with a portable 3-dimensional ultrasound bladder scanner

International Nuclear Information System (INIS)

Ahmad, Rozilawati; Hoogeman, Mischa S.; Quint, Sandra; Mens, Jan Willem; Pree, Ilse de; Heijmen, Ben J.M.

2008-01-01

Background and Purpose: For cervical cancer patients, bladder filling variations may result in inadequate EBRT target coverage, unless large safety margins are used. For a group of patients who received full bladder instructions, inter-fraction variations and time trends in bladder volume were quantified, and a 3D ultrasound (US) scanner was tested for on-line bladder volume measurements. Methods and materials: For 24 patients, the bladder volume was measured with US at the time of the planning CT scan, and twice weekly during the course of RT. Comparisons of US with planning CT were used to assess the bladder scanner accuracy. Patients were treated in prone on a belly board, EPID images were acquired to correlate set-up errors with bladder filling variations. Results: Measured US and CT bladder volumes were strongly correlated (R = 0.97, slope 1.1 ± 0.1). The population mean bladder volume at planning of 378 ± 209 ml (1 SD) reduced to 109 ± 88 ml (1 SD) in week 6, a reduction by 71% (average reduction 46 ml/week), revealing a large inter-fraction time trend. Intra-patient variation in bladder volume during RT was 168 ml (1 SD) (range 70-266 ml). Rotation around the LR axis was significantly correlated with bladder volume changes. Conclusions: Despite a full bladder instruction, bladder volumes reduced dramatically during treatment, implying large time trends in target position of these patients. The portable US scanner provides a quick and reliable measurement of the bladder volume, which might assist future online treatment adaptation

Is the hypothesis about a low entropy initial state of the Universe necessary for explaining the arrow of time?

Science.gov (United States)

Goldstein, Sheldon; Tumulka, Roderich; Zanghı, Nino

2016-07-01

According to statistical mechanics, microstates of an isolated physical system (say, a gas in a box) at time t0 in a given macrostate of less-than-maximal entropy typically evolve in such a way that the entropy at time t increases with |t -t0| in both time directions. In order to account for the observed entropy increase in only one time direction, the thermodynamic arrow of time, one usually appeals to the hypothesis that the initial state of the Universe was one of very low entropy. In certain recent models of cosmology, however, no hypothesis about the initial state of the Universe is invoked. We discuss how the emergence of a thermodynamic arrow of time in such models can nevertheless be compatible with the above-mentioned consequence of statistical mechanics, appearances to the contrary notwithstanding.

Preanalytical and analytical variation of surface-enhanced laser desorption-ionization time-of-flight mass spectrometry of human serum

DEFF Research Database (Denmark)

Albrethsen, Jakob; Bøgebo, Rikke; Olsen, Jesper

2006-01-01

BACKGROUND: Surface-enhanced laser desorption-ionization time-of-flight (SELDI-TOF) mass spectrometry of human serum is a potential diagnostic tool in human diseases. In the present study, the preanalytical and analytical variation of SELDI-TOF mass spectrometry of serum was assessed in healthy...... was 18% (6%-34%, n=4) for 16 peaks, and inter-individual CV was 38% (16%-56%, n=16) for 20 peaks. CONCLUSIONS: The pre-analytical and analytical conditions of SELDI-TOF mass spectrometry of serum have a significant impact on the protein peaks, with the number of peaks low and the assay variation high...

Measuring the universe our historic quest to chart the horizons of space and time

CERN Document Server

Ferguson, Kitty

1999-01-01

More than 2,000 years ago, Eratosthenes, in Alexandria, used a stick, a hole in the ground, sunllght at summer solstice, and elementary geometry to measure the circumference of the Earth with surprising accuracy, long before anyone was able to circumnavigate it. Today, scientists are attempting to measure the entire universe and to determine its origin. Although the methods have changed, the quest to chart the horizons of space and time continues to be one of the great adventures of science. Measuring the Universe is an eloquent chronicle of the men and women– from Aristarchus to Cassini, Sir Isaac Newton to Henrietta Leavitt and Stephen Hawking–who have gradually unlocked the mysteries of "how far" and in so doing have changed our ideas about the size and nature of the universe and our place in it. Kitty Ferguson reveals their methods to have been as inventive as their results were–and are–eye-opening. Advances such as Copernicus's revolutionary insights about the arrangement of the solar system, Wi...

Surface Temperature Variation Prediction Model Using Real-Time Weather Forecasts

Science.gov (United States)

Karimi, M.; Vant-Hull, B.; Nazari, R.; Khanbilvardi, R.

2015-12-01

Combination of climate change and urbanization are heating up cities and putting the lives of millions of people in danger. More than half of the world's total population resides in cities and urban centers. Cities are experiencing urban Heat Island (UHI) effect. Hotter days are associated with serious health impacts, heart attaches and respiratory and cardiovascular diseases. Densely populated cities like Manhattan, New York can be affected by UHI impact much more than less populated cities. Even though many studies have been focused on the impact of UHI and temperature changes between urban and rural air temperature, not many look at the temperature variations within a city. These studies mostly use remote sensing data or typical measurements collected by local meteorological station networks. Local meteorological measurements only have local coverage and cannot be used to study the impact of UHI in a city and remote sensing data such as MODIS, LANDSAT and ASTER have with very low resolution which cannot be used for the purpose of this study. Therefore, predicting surface temperature in urban cities using weather data can be useful.Three months of Field campaign in Manhattan were used to measure spatial and temporal temperature variations within an urban setting by placing 10 fixed sensors deployed to measure temperature, relative humidity and sunlight. Fixed instrument shelters containing relative humidity, temperature and illumination sensors were mounted on lampposts in ten different locations in Manhattan (Vant-Hull et al, 2014). The shelters were fixed 3-4 meters above the ground for the period of three months from June 23 to September 20th of 2013 making measurements with the interval of 3 minutes. These high resolution temperature measurements and three months of weather data were used to predict temperature variability from weather forecasts. This study shows that the amplitude of spatial and temporal variation in temperature for each day can be predicted

The Construction of Professional Identity and Pathways of Participation of Full Time Faculty Members in University Restructuring in Mexico

Science.gov (United States)

Montero Hernandez, Virginia

2010-01-01

Since the 1990s, the federal government required public state universities in Mexico to recruit full time faculty members with doctoral degrees and research productivity to increase the academic competitiveness of higher education. After two decades of the implementation of federal mandates, public state universities have not improved their…

The pattern of time management in college students of Kerman University of Medical Sciences in the year 2006

Directory of Open Access Journals (Sweden)

Ali Ravari

2008-09-01

Full Text Available Background: One potential coping strategy frequently offered by university counseling services is time management for studying. Besides stress relief, time management skills will positively influence key outcomes such as academic performance, problem-solving ability, and health. Thus, it is necessary to investigate how college students manage their timing for studying. The aim of the present study was to assess the pattern of college students' time management in Kerman University of Medical Sciences. Methods: This cross-sectional study was conducted on 300 students who were selected by stratified random sampling method among students of Kerman University of Medical Sciences. Information about how students managed their study time during their educational course was collected using a questionnaire which consisted time management stages such as planning, prioritizing, time allocation, listing all study-related tasks and goal setting. Study time management was measured according to Likert scale in range of “never” to “always”. Results: There was a significant difference between the course of study and the mean of study duration (p<0.004. Mean scores of the study time management showed that the medical students (mean=67.5 ±12.87 had the highest scores and the bachelor students (mean= 61.1±15.1 had the lowest scores, but the ANOVA test did not show any significant difference between the mean scores of study time management and the course of study (p=0.07. The majority of students (186 persons=62% “occasionally” and only 48 persons (16% “always” were managing their study time. A total of 26.2% of medical students always managed their study time, and in this criterion they had the highest scores in comparison with others. There was no significant difference between the course of study and the pattern of study management (p<0.05. Conclusion: Most of the students of medical sciences have no scheduled programming for their study time

Leisure Times Status Amongst Students of Shahid Sadoughi University of Medical Sciences –Yazd, Iran

OpenAIRE

Mohammad Hassan Lotfi; Amir Houssain Aminian; Aghdasea Ghomizadea

2011-01-01

A large number of the selected students are admitting for the Iranian University to acquire scientific and insight subjects annually. In this way, exposing to different cultural manners, new conditions of educational and dormitory residence place can affect psycho-social aspects of students where a not good planning for fulfilling times of leisure can produce psycho-social problems. This analytic cross sectional study was planned to evaluate the status of lesiure time amongst students of Shah...

Seasonal variation of residence time in spring and groundwater evaluated by CFCs and numerical simulation in mountainous headwater catchment

Science.gov (United States)

Tsujimura, Maki; Watanabe, Yasuto; Ikeda, Koichi; Yano, Shinjiro; Abe, Yutaka

2016-04-01

Headwater catchments in mountainous region are the most important recharge area for surface and subsurface waters, additionally time information of the water is principal to understand hydrological processes in the catchments. However, there have been few researches to evaluate variation of residence time of subsurface water in time and space at the mountainous headwaters especially with steep slope. We investigated the temporal variation of the residence time of the spring and groundwater with tracing of hydrological flow processes in mountainous catchments underlain by granite, Yamanashi Prefecture, central Japan. We conducted intensive hydrological monitoring and water sampling of spring, stream and ground waters in high-flow and low-flow seasons from 2008 through 2013 in River Jingu Watershed underlain by granite, with an area of approximately 15 km2 and elevation ranging from 950 m to 2000 m. The CFCs, stable isotopic ratios of oxygen-18 and deuterium, inorganic solute constituent concentrations were determined on all water samples. Also, a numerical simulation was conducted to reproduce of the average residence times of the spring and groundwater. The residence time of the spring water estimated by the CFCs concentration ranged from 10 years to 60 years in space within the watershed, and it was higher (older) during the low flow season and lower (younger) during the high flow season. We tried to reproduce the seasonal change of the residence time in the spring water by numerical simulation, and the calculated residence time of the spring water and discharge of the stream agreed well with the observed values. The groundwater level was higher during the high flow season and the groundwater dominantly flowed through the weathered granite with higher permeability, whereas that was lower during the low flow season and that flowed dominantly through the fresh granite with lower permeability. This caused the seasonal variation of the residence time of the spring

The variation of the density functions on chaotic spheres in chaotic space-like Minkowski space time

International Nuclear Information System (INIS)

El-Ahmady, A.E.

2007-01-01

In this article we introduce types of chaotic spheres in chaotic space-like Minkowski space time M n+1 . The variations of the density functions under the folding of these chaotic spheres are defined. The foldings restriction imposed on the density function are also discussed. The relations between the folding of geometry and pure chaotic manifolds are deduced. Some theorems concerning these relations are presented

Coarse Grained Exponential Variational Autoencoders

KAUST Repository

Sun, Ke

2017-02-25

Variational autoencoders (VAE) often use Gaussian or category distribution to model the inference process. This puts a limit on variational learning because this simplified assumption does not match the true posterior distribution, which is usually much more sophisticated. To break this limitation and apply arbitrary parametric distribution during inference, this paper derives a \\\\emph{semi-continuous} latent representation, which approximates a continuous density up to a prescribed precision, and is much easier to analyze than its continuous counterpart because it is fundamentally discrete. We showcase the proposition by applying polynomial exponential family distributions as the posterior, which are universal probability density function generators. Our experimental results show consistent improvements over commonly used VAE models.

Influence of Conditioning Time of Universal Adhesives on Adhesive Properties and Enamel-Etching Pattern.

Science.gov (United States)

Cardenas, A M; Siqueira, F; Rocha, J; Szesz, A L; Anwar, M; El-Askary, F; Reis, A; Loguercio, A

2016-01-01

To evaluate the effect of application protocol in resin-enamel microshear bond strength (μSBS), in situ degree of conversion, and etching pattern of three universal adhesive systems. Sixty-three extracted third molars were sectioned in four parts (buccal, lingual, and proximals) and divided into nine groups, according to the combination of the main factors-Adhesive (Clearfil Universal, Kuraray Noritake Dental Inc, Tokyo, Japan; Futurabond U, VOCO, Cuxhaven, Germany; and Scotchbond Universal Adhesive, 3M ESPE, St Paul, MN, USA)-and enamel treatment/application time (etch-and-rinse mode [ER], self-etch [SE] application for 20 seconds [SE20], and SE application for 40 seconds [SE40]). Specimens were stored in water (37°C/24 h) and tested at 1.0 mm/min (μSBS). The degree of conversion of the adhesives at the resin-enamel interfaces was evaluated using micro-Raman spectroscopy. The enamel-etching pattern was evaluated under a scanning electron microscope. Data were analyzed with two-way analysis of variance and Tukey test (α=0.05). In general, the application of the universal adhesives in the SE40 produced μSBS and degree of conversion that were higher than in the SE20 (puniversal adhesives in the SE mode may be a viable alternative to increase the degree of conversion, etching pattern, and resin-enamel bond strength.

Existence of evolutionary variational solutions via the calculus of variations

Science.gov (United States)

Bögelein, Verena; Duzaar, Frank; Marcellini, Paolo

In this paper we introduce a purely variational approach to time dependent problems, yielding the existence of global parabolic minimizers, that is ∫0T ∫Ω [uṡ∂tφ+f(x,Du)] dx dt⩽∫0T ∫Ω f(x,Du+Dφ) dx dt, whenever T>0 and φ∈C0∞(Ω×(0,T),RN). For the integrand f:Ω×R→[0,∞] we merely assume convexity with respect to the gradient variable and coercivity. These evolutionary variational solutions are obtained as limits of maps depending on space and time minimizing certain convex variational functionals. In the simplest situation, with some growth conditions on f, the method provides the existence of global weak solutions to Cauchy-Dirichlet problems of parabolic systems of the type ∂tu-divDξf(x,Du)=0 in Ω×(0,∞).

Using a "time machine" to test for local adaptation of aquatic microbes to temporal and spatial environmental variation.

Science.gov (United States)

Fox, Jeremy W; Harder, Lawrence D

2015-01-01

Local adaptation occurs when different environments are dominated by different specialist genotypes, each of which is relatively fit in its local conditions and relatively unfit under other conditions. Analogously, ecological species sorting occurs when different environments are dominated by different competing species, each of which is relatively fit in its local conditions. The simplest theory predicts that spatial, but not temporal, environmental variation selects for local adaptation (or generates species sorting), but this prediction is difficult to test. Although organisms can be reciprocally transplanted among sites, doing so among times seems implausible. Here, we describe a reciprocal transplant experiment testing for local adaptation or species sorting of lake bacteria in response to both temporal and spatial variation in water chemistry. The experiment used a -80°C freezer as a "time machine." Bacterial isolates and water samples were frozen for later use, allowing transplantation of older isolates "forward in time" and newer isolates "backward in time." Surprisingly, local maladaptation predominated over local adaptation in both space and time. Such local maladaptation may indicate that adaptation, or the analogous species sorting process, fails to keep pace with temporal fluctuations in water chemistry. This hypothesis could be tested with more finely resolved temporal data. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

Value of H, space-time patterns, vacuum, matter, expansion of the Universe, alternative cosmologies

Directory of Open Access Journals (Sweden)

Gonzalez-Mestres Luis

2017-01-01

Full Text Available To the experimental uncertainties on the present value H0 of the Lundmark - Lemaître-Hubble constant, fundamental theoretical uncertainties of several kinds should also be added. In standard Cosmology, consistency problems are really serious. The cosmological constant is a source of well-known diffculties while the associated dark energy is assumed to be at the origin of the observed acceleration of the expansion of the Universe. But in alternative cosmologies, possible approaches without these problems exist. An example is the pattern based on the spinorial space-time (SST we introduced in 1996-97 where the H t = 1 relation (t = cosmic time = age of the Universe is automatically generated by a pre-existing cosmic geometry before standard matter and conventional forces, including gravitation and relativity, are introduced. We analyse present theoretical, experimental and observational uncertainties, focusing also on the possible sources of the acceleration of the expansion of the Universe as well as on the structure of the physical vacuum and its potential cosmological role. Particular attention is given to alternative approaches to both Particle Physics and Cosmology including possible preonic constituents of the physical vacuum and associated pre-Big Bang patterns. A significant example is provided by the cosmic SST geometry together with the possibility that the expanding cosmological vacuum releases energy in the form of standard matter and dark matter, thus modifying the dependence of the matter energy density with respect to the age and size of our Universe. The SST naturally generates a new leading contribution to the value of H. If the matter energy density decreases more slowly than in standard patterns, it can naturally be at the origin of the observed acceleration of the expansion of the Universe. The mathematical and dynamical structure of standard Physics at very short distances can also be modified by an underlying preonic

Value of H, space-time patterns, vacuum, matter, expansion of the Universe, alternative cosmologies

Science.gov (United States)

Gonzalez-Mestres, Luis

2017-12-01

To the experimental uncertainties on the present value H0 of the Lundmark - Lemaître-Hubble constant, fundamental theoretical uncertainties of several kinds should also be added. In standard Cosmology, consistency problems are really serious. The cosmological constant is a source of well-known diffculties while the associated dark energy is assumed to be at the origin of the observed acceleration of the expansion of the Universe. But in alternative cosmologies, possible approaches without these problems exist. An example is the pattern based on the spinorial space-time (SST) we introduced in 1996-97 where the H t = 1 relation (t = cosmic time = age of the Universe) is automatically generated by a pre-existing cosmic geometry before standard matter and conventional forces, including gravitation and relativity, are introduced. We analyse present theoretical, experimental and observational uncertainties, focusing also on the possible sources of the acceleration of the expansion of the Universe as well as on the structure of the physical vacuum and its potential cosmological role. Particular attention is given to alternative approaches to both Particle Physics and Cosmology including possible preonic constituents of the physical vacuum and associated pre-Big Bang patterns. A significant example is provided by the cosmic SST geometry together with the possibility that the expanding cosmological vacuum releases energy in the form of standard matter and dark matter, thus modifying the dependence of the matter energy density with respect to the age and size of our Universe. The SST naturally generates a new leading contribution to the value of H. If the matter energy density decreases more slowly than in standard patterns, it can naturally be at the origin of the observed acceleration of the expansion of the Universe. The mathematical and dynamical structure of standard Physics at very short distances can also be modified by an underlying preonic structure. If preons are

Exploring the relationship between university internationalization and university autonomy

DEFF Research Database (Denmark)

Turcan, Romeo V.; Gullieva, Valeria

This paper explores a research gap at the intersection of university internationalization and university autonomy. A process model of university internationalization is put forward whereby the process of university internationalization is mediated by university internationalization capacity...... and moderated by target country institutional autonomy and globalization; and entry modes, timing and pace, as well as product mix of internationalization define university’s internationalization pattern. A systematic review is conducted to identify empirical studies at this intersection. One of the questions...

Isochronization calculations for the Indiana University cyclotron

International Nuclear Information System (INIS)

Jones, W.P.

1975-01-01

A series of calculations using measured magnetic fields was performed to determine the optimal gradient coil currents for the wide range of operating conditions to be experienced by the Indiana University main stage cyclotron. Depending on the particle type to be accelerated and final energy desired, the required radial field increase varies from 0.5 percent to 22 percent. An iterative least squares fitting technique is used to minimize orbit time variations. For the acceleration of 200 MeV protons (330 revolutions, fourth harmonic), the maximum phase excursion is predicted to be less than two rf degrees. The technique used can be adapted to using measured phase histories to predict corrections to gradient coil currents. (auth)

The "Nursing Home Compare" measure of urinary/fecal incontinence: cross-sectional variation, stability over time, and the impact of case mix.

Science.gov (United States)

Li, Yue; Schnelle, John; Spector, William D; Glance, Laurent G; Mukamel, Dana B

2010-02-01

To assess the impact of facility case mix on cross-sectional variations and short-term stability of the "Nursing Home Compare" incontinence quality measure (QM) and to determine whether multivariate risk adjustment can minimize such impacts. Retrospective analyses of the 2005 national minimum data set (MDS) that included approximately 600,000 long-term care residents in over 10,000 facilities in each quarterly sample. Mixed logistic regression was used to construct the risk-adjusted QM (nonshrinkage estimator). Facility-level ordinary least-squares models and adjusted R(2) were used to estimate the impact of case mix on cross-sectional and short-term longitudinal variations of currently published and risk-adjusted QMs. At least 50 percent of the cross-sectional variation and 25 percent of the short-term longitudinal variation of the published QM are explained by facility case mix. In contrast, the cross-sectional and short-term longitudinal variations of the risk-adjusted QM are much less susceptible to case-mix variations (adjusted R(2)case-mix variations across facilities and over time, and therefore it may be biased. This issue can be largely addressed by multivariate risk adjustment using risk factors available in the MDS.

Consideration of the accuracy by variation of respiration in real-time position management respiratory gating system

International Nuclear Information System (INIS)

Na, Jun Young; Kang, Tae Young; Beak, Geum Mun; Kwon, Gyeong Tae

2013-01-01

Respiratory Gated Radiation Therapy (RGRT) has been carried out using RPM (Real-time Position Management) Respiratory Gating System (version 1.7.5, varian, USA) in Asan Medical Center. This study was to analyze and evaluate the accuracy of Respiratory Gated Radiation Therapy (RGRT) according to variation of respiration. Making variation of respiration using Motion Phantom:QUASAR Programmable Respiratory Motion Phantom (Moudus Medical Device Inc. CANADA) able to adjust respiration pattern randomly was varying period, amplitude and baseline by analyze 50 patient's respiration of lung and liver cancer. One of the variations of respiration is baseline shift gradually downward per 0.01 cm, 0.03 cm, 0.05 cm. The other variation of respiration is baseline shift accidently downward per 0.2 cm, 0.4 cm, 0.6 cm, 0.8 cm. Experiments were performed in the same way that is used RPM Respiratory Gating System (phase gating, usually 30-70% gating) in Asan Medical Center. It was all exposed radiation under one of the conditions of baseline shift gradually downward per 0.01 cm, 0.03 cm, 0.05 cm. Under the other condition of baseline shift accidently downward per 0.2 cm, 0.4 cm, 0.6 cm, 0.8 cm equally radiation was exposed. The variations of baseline shifts didn't accurately reflect on phase gating in RPM Respiratory Gating System. This inexactitude makes serious uncertainty in Respiratory Gated Radiation Therapy. So, Must be stabilized breathing of patient before conducting Respiratory Gated Radiation Therapy. also must be monitored breathing of patient in the middle of treatment. If you observe considerable changes of breathing when conducting Respiratory Gated Radiation Therapy. Stopping treatment immediately and then must be need to recheck treatment site using fluoroscopy. If patient's respiration rechecked using fluoroscopy restabilize, it is possible to restart Respiratory Gated Radiation Therapy

Perceived Quality of Service and Behavioral Intentions of First-Time Students Enrolled at The University of North Carolina Asheville

Science.gov (United States)

Mitchell, Patrice Black

2011-01-01

The purpose of this study was to use the SERVQUAL (Service Quality Instrument) to examine the perceptions of first-time enrolled students at University of North Carolina Asheville regarding the services they receive from a selected group of departments in the university's One Stop area. In addition, the study examined whether a relationship…

Evidence for universality and cultural variation of differential emotion response patterning.

Science.gov (United States)

Scherer, K R; Wallbott, H G

1994-02-01

The major controversy concerning psychobiological universality of differential emotion patterning versus cultural relativity of emotional experience is briefly reviewed. Data from a series of cross-cultural questionnaire studies in 37 countries on 5 continents are reported and used to evaluate the respective claims of the proponents in the debate. Results show highly significant main effects and strong effect sizes for the response differences across 7 major emotions (joy, fear, anger, sadness, disgust, shame, and guilt). Profiles of cross-culturally stable differences among the emotions with respect to subjective feeling, physiological symptoms, and expressive behavior are also reported. The empirical evidence is interpreted as supporting theories that postulate both a high degree of universality of differential emotion patterning and important cultural differences in emotion elicitation, regulation, symbolic representation, and social sharing.

Effects of detector-source distance and detector bias voltage variations on time resolution of general purpose plastic scintillation detectors.

Science.gov (United States)

Ermis, E E; Celiktas, C

2012-12-01

Effects of source-detector distance and the detector bias voltage variations on time resolution of a general purpose plastic scintillation detector such as BC400 were investigated. (133)Ba and (207)Bi calibration sources with and without collimator were used in the present work. Optimum source-detector distance and bias voltage values were determined for the best time resolution by using leading edge timing method. Effect of the collimator usage on time resolution was also investigated. Copyright © 2012 Elsevier Ltd. All rights reserved.

Dynamic Variation in Sexual Contact Rates in a Cohort of HIV-Negative Gay Men.

Science.gov (United States)

Romero-Severson, E O; Volz, E; Koopman, J S; Leitner, T; Ionides, E L

2015-08-01

Human immunodeficiency virus (HIV) transmission models that include variability in sexual behavior over time have shown increased incidence, prevalence, and acute-state transmission rates for a given population risk profile. This raises the question of whether dynamic variation in individual sexual behavior is a real phenomenon that can be observed and measured. To study this dynamic variation, we developed a model incorporating heterogeneity in both between-person and within-person sexual contact patterns. Using novel methodology that we call iterated filtering for longitudinal data, we fitted this model by maximum likelihood to longitudinal survey data from the Centers for Disease Control and Prevention's Collaborative HIV Seroincidence Study (1992-1995). We found evidence for individual heterogeneity in sexual behavior over time. We simulated an epidemic process and found that inclusion of empirically measured levels of dynamic variation in individual-level sexual behavior brought the theoretical predictions of HIV incidence into closer alignment with reality given the measured per-act probabilities of transmission. The methods developed here provide a framework for quantifying variation in sexual behaviors that helps in understanding the HIV epidemic among gay men. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Variations of the Blazar AO 0235+164 in 2006-2015

Science.gov (United States)

Hagen-Thorn, V. A.; Larionov, V. M.; Morozova, D. A.; Arkharov, A. A.; Hagen-Thorn, E. I.; Shablovinskaya, E. S.; Prokop'eva, M. S.; Yakovleva, V. A.

2018-02-01

The results of optical, radio, and gamma-ray observations of the blazar AO 0235+16 are presented, including photometric ( BV RIJHK) and polarimetric ( R)monitoring carried out at St. Petersburg State University and the Central (Pulkovo) Astronomical Observatory in 2007-2015, 43 GHz Very Long Baseline Interferometry radio observations processed at Boston University, and a gamma-ray light curve based on observationswith the Fermi space observatory are presented. Two strong outbursts were detected. The relative spectral energy distributions of the variable components responsible for the outbursts are determined; these follow power laws, but with different spectral indices. The degree of polarization was high in both outbursts; only an average relationship between the brightness and polarization can be found. There was no time lag between the variations in the optical and gamma-ray, suggesting that the sources of the radiation in the optical and gamma-ray are located in the same region of the jet.

Time-Driven Activity-Based Costing for Inter-Library Services: A Case Study in a University

Science.gov (United States)

Pernot, Eli; Roodhooft, Filip; Van den Abbeele, Alexandra

2007-01-01

Although the true costs of inter-library loans (ILL) are unknown, universities increasingly rely on them to provide better library services at lower costs. Through a case study, we show how to perform a time-driven activity-based costing analysis of ILL and provide evidence of the benefits of such an analysis.

Fast solution of Cahn–Hilliard variational inequalities using implicit time discretization and finite elements

KAUST Repository

Bosch, Jessica

2014-04-01

We consider the efficient solution of the Cahn-Hilliard variational inequality using an implicit time discretization, which is formulated as an optimal control problem with pointwise constraints on the control. By applying a semi-smooth Newton method combined with a Moreau-Yosida regularization technique for handling the control constraints we show superlinear convergence in function space. At the heart of this method lies the solution of large and sparse linear systems for which we propose the use of preconditioned Krylov subspace solvers using an effective Schur complement approximation. Numerical results illustrate the competitiveness of this approach. © 2014 Elsevier Inc.

Canonical variate regression.

Science.gov (United States)

Luo, Chongliang; Liu, Jin; Dey, Dipak K; Chen, Kun

2016-07-01

In many fields, multi-view datasets, measuring multiple distinct but interrelated sets of characteristics on the same set of subjects, together with data on certain outcomes or phenotypes, are routinely collected. The objective in such a problem is often two-fold: both to explore the association structures of multiple sets of measurements and to develop a parsimonious model for predicting the future outcomes. We study a unified canonical variate regression framework to tackle the two problems simultaneously. The proposed criterion integrates multiple canonical correlation analysis with predictive modeling, balancing between the association strength of the canonical variates and their joint predictive power on the outcomes. Moreover, the proposed criterion seeks multiple sets of canonical variates simultaneously to enable the examination of their joint effects on the outcomes, and is able to handle multivariate and non-Gaussian outcomes. An efficient algorithm based on variable splitting and Lagrangian multipliers is proposed. Simulation studies show the superior performance of the proposed approach. We demonstrate the effectiveness of the proposed approach in an [Formula: see text] intercross mice study and an alcohol dependence study. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Variational principles of continuum mechanics. Vol. 1. Fundamentals

Energy Technology Data Exchange (ETDEWEB)

Berdichevsky, Victor L. [Wayne State Univ., Detroit, MI (United States). Dept. of Mechanical Engineering

2009-07-01

The book reviews the two features of the variational approach: its use as a universal tool to describe physical phenomena and as a source for qualitative and quantitative methods of studying particular problems. Berdichevsky's work differs from other books on the subject in focusing mostly on the physical origin of variational principles as well as establishing their interrelations. For example, the Gibbs principles appear as a consequence of the Einstein formula for thermodynamic fluctuations rather than as the first principles of the theory of thermodynamic equilibrium. Mathematical issues are considered as long as they shed light on the physical outcomes and/or provide a useful technique for the direct study of variational problems. In addition, a thorough account of variational principles discovered in various branches of continuum mechanics is given. In this book, the first volume, the author covers the variational principles for systems with a finite number of degrees of freedom; the variational principles of thermodynamics; the basics of continuum mechanics; the variational principles for classical models of continuum mechanics, such as elastic and plastic bodies, and ideal and viscous fluids; and direct methods of calculus of variations. (orig.)

Time resolved FTIR study of the catalytic CO oxidation under periodic variation of the reactant concentration

Energy Technology Data Exchange (ETDEWEB)

Kritzenberger, J; Wokaun, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-06-01

Oxidation of CO over palladium/zirconia catalyst obtained from an amorphous Pd{sub 25}Zr{sub 75} precursor was investigated by time resolved FTIR spectroscopy. Sine wave shaped modulation of the reactant concentration, i.e. variation of CO or O{sub 2} partial pressure, was used to induce variations of the IR signals of product (CO{sub 2}) and unconverted reactant (CO), which were detected in a multi-pass absorption cell. The phase shift {phi} between external perturbation and variation of the CO{sub 2} signal was examined in dependence on temperature (100{sup o}C{<=}T{<=}350{sup o}C) and modulation frequency (1.39x10{sup -4}Hz{<=}{omega}{<=}6.67x10{sup -2}Hz). From the phase shift values, a simple Eley-Rideal mechanism is excluded, and the rate limiting step of the Langmuir-Hinshelwood mechanism for the CO oxidation may be identified. Adsorption and possible surface movement of CO to the actual reaction site determine the rate of the CO oxidation on the palladium/zirconia catalyst used in our study. The introduction of an external perturbation is a first step towards the application of two-dimensional infrared spectroscopy to heterogeneous catalyzed reactions. (author) 3 figs., 4 refs.

Drift time variations in CdZnTe detectors measured with alpha-particles: Their correlation with the detector’s responses

Energy Technology Data Exchange (ETDEWEB)

Bolotnikov A. E.; Butcher, J.; Hamade, M.; Petryk, M.; Bolotnikov, A.; Camarda, G.; Cui, Y.; Hossain, A.; Kim, K.; Yang, G.; and James, R.

2012-05-14

Homogeneity of properties related to material crystallinity is a critical parameter for achieving high-performance CdZnTe (CZT) radiation detectors. Unfortunately, this requirement is not always satisfied in today's commercial CZT material due to high concentrations of extended defects, in particular subgrain boundaries, which are believed to be part of the causes hampering the energy resolution and efficiency of CZT detectors. In the past, the effects of subgrain boundaries have been studied in Si, Ge and other semiconductors. It was demonstrated that subgrain boundaries tend to accumulate secondary phases and impurities causing inhomogeneous distributions of trapping centers. It was also demonstrated that subgrain boundaries result in local perturbations of the electric field, which affect the carrier transport and other properties of semiconductor devices. The subgrain boundaries in CZT material likely behave in a similar way, which makes them responsible for variations in the electron drift time and carrier trapping in CZT detectors. In this work, we employed the transient current technique to measure variations in the electron drift time and related the variations to the device performances and subgrain boundaries, whose presence in the crystals were confirmed with white beam X-ray diffraction topography and infrared transmission microscopy.

On the Time Variation of Dust Extinction and Gas Absorption for Type Ia Supernovae Observed Through Non-uniform Interstellar Medium

Science.gov (United States)

Huang, Xiaosheng; Aldering, Gregory; Biederman, Moriah; Herger, Brendan

2018-01-01

For Type Ia supernovae (SNe Ia) observed through a non-uniform interstellar medium (ISM) in its host galaxy, we investigate whether the non-uniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures (>~ 10 pc) will translate to much smaller fluctuations on the scales of a SN photosphere. Therefore the typical amplitude of time variation due to non-uniform ISM, of absorption equivalent widths and of extinction, would be small. As a result, we conclude that non-uniform ISM density should not impact cosmology measurements based on SNe Ia. We apply our predictions based on the ISM density power law power spectrum to the observations of two highly reddened SNe Ia, SN 2012cu and SN 2014J.

On the Time Variation of Dust Extinction and Gas Absorption for Type Ia Supernovae Observed through a Nonuniform Interstellar Medium

Science.gov (United States)

Huang, X.; Aldering, G.; Biederman, M.; Herger, B.

2017-11-01

For Type Ia supernovae (SNe Ia) observed through a nonuniform interstellar medium (ISM) in its host galaxy, we investigate whether the nonuniformity can cause observable time variations in dust extinction and in gas absorption due to the expansion of the SN photosphere with time. We show that, owing to the steep spectral index of the ISM density power spectrum, sizable density fluctuation amplitudes at the length scale of typical ISM structures (≳ 10 {pc}) will translate to much smaller fluctuations on the scales of an SN photosphere. Therefore, the typical amplitude of time variation due to a nonuniform ISM, of absorption equivalent widths, and of extinction, would be small. As a result, we conclude that nonuniform ISM density should not impact cosmology measurements based on SNe Ia. We apply our predictions based on the ISM density power-law power spectrum to the observations of two highly reddened SNe Ia, SN 2012cu and SN 2014J.

Seasonal variations of aerosol residence time in the lower atmospheric boundary layer

International Nuclear Information System (INIS)

Ahmed, A.A.; Mohamed, A.; Ali, A.E.; Barakat, A.; Abd El-Hady, M.; El-Hussein, A.

2004-01-01

During a one year period, from Jan. 2002 up to Dec. 2002, approximately 130 air samples were analyzed to determine the atmospheric air activity concentrations of short- and long-lived ( 222 Rn) decay products 214 Pb and 210 Pb. The samples were taken by using a single-filter technique and γ-spectrometry was applied to determine the activity concentrations. A seasonal fluctuation in the concentration of 214 Pb and 210 Pb in surface air was observed. The activity concentrations of both radionuclides were observed to be relatively higher during the winter/autumn season than in spring/summer season. The mean activity concentration of 214 Pb and 210 Pb within the whole year was found to be 1.4±0.27 Bq m -3 and 1.2±0.15 mBq m -3 , respectively. Different 210 Pb: 214 Pb activity ratios during the year varied between 1.78x10 -4 and 1.6x10 -3 with a mean value of 8.9x10 -4 ±7.6x10 -5 . From the ratio between the activity concentrations of the radon decay products 214 Pb and 210 Pb a mean residence time (MRT) of aerosol particles in the atmosphere of about 10.5±0.91 d could be estimated. The seasonal variation pattern shows relatively higher values of MRT in spring/summer season than in winter/autumn season. The MRT data together with relative humidity (RH), air temperature (T) and wind speed (WS), were used for a comprehensive regression analysis of its seasonal variation in the atmospheric air

[Work satisfaction, quality of life and leisure time of residents at the Soroka University Medical Center, Beer Sheba, Israel].

Science.gov (United States)

Acker, Asaf; Perry, Zvi; Reuveni, Haim; Toker, Asaf

2009-02-01

Work dissatisfaction among physicians worldwide continues to rise over the last few decades, mainly due to declining professional prestige, tack of self fulfillment, time pressure and tack of leisure time. Physicians' burnout is a major result of dissatisfaction, causing doctors to leave the medical profession, and to provide lower quality of care. To examine the work satisfaction, quality of life and leisure time of residents in the Soroka University Medical Center. A validated questionnaire was delivered during the second half of 2004 to 252 residents in the Soroka University Medical Center The data was analyzed using the SPSS 12 for windows program. Descriptive analysis, parametric Students' T Test [where pleisure time. Further attention must be given to these matters--a step which will eventually improve patient care, and delay, to some extent, the burnout of physicians.

Solar ultraviolet irradiance variations: a review

International Nuclear Information System (INIS)

Lean, J.

1987-01-01

Despite the geophysical importance of solar ultraviolet radiation, specific aspects of its temporal variations have not yet been adequately determined experimentally, nor are the mechanisms for the variability completely understood. Satellite observations have verified the reality of solar ultraviolet irradiance variations over time scales of days and months, and model calculations have confirmed the association of these short-term variations with the evolution and rotation of regions of enhanced magnetic activity on the solar disc. However, neither rocket nor satellite measurements have yet been made with sufficient accuracy and regularity to establish unequivocally the nature of the variability over the longer time of the 11-year solar cycle. The comparative importance for the long-term variations of local regions of enhanced magnetic activity and global scale activity perturbations is still being investigated. Solar ultraviolet irradiance variations over both short and long time scales are reviewed, with emphasis on their connection to solar magnetic activity. Correlations with ground-based measures of solar variability are examined because of the importance of the ground-based observations as historical proxies of ultraviolet irradiance variations. Current problems in understanding solar ultraviolet irradiance variations are discussed, and the measurements planned for solar cycle 22, which may resolve these problems, are briefly described. copyright American Geophysical Union 1987

TIME VARIATION AND ASYMMETRY IN THE WORLD PRICE OF COVARIANCE RISK: THE IMPLICATIONS FOR INTERNATIONAL DIVERSIFICATION

OpenAIRE

Olan T. Henry; Nilss Olekalns; Kalvinder Shields

2004-01-01

The International Capital Asset Pricing Model measures country risk in terms of the conditional covariance of national returns with the world return. Using impulse responses from a multivariate nonlinear model we provide evidence of time variation and asymmetry in the measure of country risk. and the implied benefit to international diversification. The evidence implies that the price of risk and the benefits from diversification may differ in a statistically and economically meaningful fashi...

The High Time Resolution Universe surveys for pulsars and fast transients

Science.gov (United States)

Keith, Michael J.

2013-03-01

The High Time Resolution Universe survey for pulsars and transients is the first truly all-sky pulsar survey, taking place at the Parkes Radio Telescope in Australia and the Effelsberg Radio Telescope in Germany. Utilising multibeam receivers with custom built all-digital recorders the survey targets the fastest millisecond pulsars and radio transients on timescales of 64 μs to a few seconds. The new multibeam digital filter-bank system at has a factor of eight improvement in frequency resolution over previous Parkes multibeam surveys, allowing us to probe further into the Galactic plane for short duration signals. The survey is split into low, mid and high Galactic latitude regions. The mid-latitude portion of the southern hemisphere survey is now completed, discovering 107 previously unknown pulsars, including 26 millisecond pulsars. To date, the total number of discoveries in the combined survey is 135 and 29 MSPs These discoveries include the first magnetar to be discovered by it's radio emission, unusual low-mass binaries, gamma-ray pulsars and pulsars suitable for pulsar timing array experiments.

Association between maternal education and objectively measured physical activity and sedentary time in adolescents

DEFF Research Database (Denmark)

Sherar, Lauren B; Griffin, T. P.; Ekelund, U.

2016-01-01

Background Investigating socioeconomic variation in physical activity (PA) and sedentary time is important as it may represent a pathway by which socioeconomic position (SEP) leads to ill health. Findings on the association between children's SEP and objectively assessed PA and/or sedentary time......) and regression coefficients combined across studies using random effects metaanalyses. Analyses were conducted in March 2014. Results Adolescents of university educated mothers spent more time sedentary (9.5 min/day, p=0.005) and less time in light activity (10 min/day, p

Geometry of the Universe

International Nuclear Information System (INIS)

Gurevich, L.Eh.; Gliner, Eh.B.

1978-01-01

Problems of investigating the Universe space-time geometry are described on a popular level. Immediate space-time geometries, corresponding to three cosmologic models are considered. Space-time geometry of a closed model is the spherical Riemann geonetry, of an open model - is the Lobachevskij geometry; and of a plane model - is the Euclidean geometry. The Universe real geometry in the contemporary epoch of development is based on the data testifying to the fact that the Universe is infinitely expanding

Sheet universes and the shapes of Friedmann universes

International Nuclear Information System (INIS)

Lynden-Bell, D.; Redmount, I.H.

1989-01-01

Unless Ω>1,the Big Bang did not start from a point. Consideration shows sheet universes in which matter is confined to a homogeneous universe. Sheet universes and the corresponding embeddings of FRW universes into Minkowski space are drawn. Their initial singularities are shown to be point-like for the 'closed' case, line-like for the 'flat' (Ω=1) case and surface-like for the 'open' case. In contrast to the cross-sections at constant comoving proper time, typical spacelike cross-sections of the 'flat' universes are closed and encounter their extensive singularities. All cross-sections of the 'closed' universe are closed and only very special cross-sections encounter the point singularities at the Big Bang or the Big Crunch. (author)

Millennial-scale climate variations recorded in Early Pliocene colour reflectance time series from the lacustrine Ptolemais Basin (NW Greece)

Science.gov (United States)

Steenbrink, J.; Kloosterboer-van Hoeve, M. L.; Hilgen, F. J.

2003-03-01

Quaternary climate proxy records show compelling evidence for climate variability on time scales of a few thousand years. The causes for these millennial-scale or sub-Milankovitch cycles are still poorly understood, not least due to the complex feedback mechanisms of large ice sheets during the Quaternary. We present evidence of millennial-scale climate variability in Early Pliocene lacustrine sediments from the intramontane Ptolemais Basin in northwestern Greece. The sediments are well exposed in a series of open-pit lignite mines and exhibit a distinct millennial-scale sedimentary cyclicity of alternating lignites and lacustrine marl beds that resulted from precession-induced variations in climate. The higher-frequency, millennial-scale cyclicity is particularly prominent within the grey-coloured marl segment of individual cycles. A stratigraphic interval of ˜115 ka, covering five precession-induced sedimentary cycles, was studied in nine parallel sections from two open-pit lignite mines located several km apart. High-resolution colour reflectance records were used to quantify the within-cycle variability and to determine its lateral continuity. Much of the within-cycle variability could be correlated between the parallel sections, even in fine detail, which suggests that these changes reflect basin-wide variations in environmental conditions related to (regional) climate fluctuations. Interbedded volcanic ash beds demonstrate the synchronicity of these fluctuations and spectral analysis of the reflectance time series shows a significant concentration of within-cycle variability at periods of ˜11, ˜5.5 and ˜2 ka. The occurrence of variability at such time scales at times before the intensification of the Northern Hemisphere glaciation suggests that they cannot solely have resulted from internal ice-sheet dynamics. Possible candidates include harmonics or combination tones of the main orbital cycles, variations in solar output or periodic motions of the Earth

Universality and the dynamical space-time dimensionality in the Lorentzian type IIB matrix model

Energy Technology Data Exchange (ETDEWEB)

Ito, Yuta [KEK Theory Center, High Energy Accelerator Research Organization,1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Nishimura, Jun [KEK Theory Center, High Energy Accelerator Research Organization,1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Graduate University for Advanced Studies (SOKENDAI),1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Tsuchiya, Asato [Department of Physics, Shizuoka University,836 Ohya, Suruga-ku, Shizuoka 422-8529 (Japan)

2017-03-27

The type IIB matrix model is one of the most promising candidates for a nonperturbative formulation of superstring theory. In particular, its Lorentzian version was shown to exhibit an interesting real-time dynamics such as the spontaneous breaking of the 9-dimensional rotational symmetry to the 3-dimensional one. This result, however, was obtained after regularizing the original matrix integration by introducing “infrared” cutoffs on the quadratic moments of the Hermitian matrices. In this paper, we generalize the form of the cutoffs in such a way that it involves an arbitrary power (2p) of the matrices. By performing Monte Carlo simulation of a simplified model, we find that the results become independent of p and hence universal for p≳1.3. For p as large as 2.0, however, we find that large-N scaling behaviors do not show up, and we cannot take a sensible large-N limit. Thus we find that there is a certain range of p in which a universal large-N limit can be taken. Within this range of p, the dynamical space-time dimensionality turns out to be (3+1), while for p=2.0, where we cannot take a sensible large-N limit, we observe a (5+1)d structure.

Dynamic linear modeling of monthly electricity demand in Japan: Time variation of electricity conservation effect.

Science.gov (United States)

Honjo, Keita; Shiraki, Hiroto; Ashina, Shuichi

2018-01-01

After the severe nuclear disaster in Fukushima, which was triggered by the Great East Japan earthquake in March 2011, nuclear power plants in Japan were temporarily shut down for mandatory inspections. To prevent large-scale blackouts, the Japanese government requested companies and households to reduce electricity consumption in summer and winter. It is reported that the domestic electricity demand had a structural decrease because of the electricity conservation effect (ECE). However, quantitative analysis of the ECE is not sufficient, and especially time variation of the ECE remains unclear. Understanding the ECE is important because Japan's NDC (nationally determined contribution) assumes the reduction of CO2 emissions through aggressive energy conservation. In this study, we develop a time series model of monthly electricity demand in Japan and estimate time variation of the ECE. Moreover, we evaluate the impact of electricity conservation on CO2 emissions from power plants. The dynamic linear model is used to separate the ECE from the effects of other irrelevant factors (e.g. air temperature, economic production, and electricity price). Our result clearly shows that consumers' electricity conservation behavior after the earthquake was not temporary but became established as a habit. Between March 2011 and March 2016, the ECE on industrial electricity demand ranged from 3.9% to 5.4%, and the ECE on residential electricity demand ranged from 1.6% to 7.6%. The ECE on the total electricity demand was estimated at 3.2%-6.0%. We found a seasonal pattern that the residential ECE in summer is higher than that in winter. The emissions increase from the shutdown of nuclear power plants was mitigated by electricity conservation. The emissions reduction effect was estimated at 0.82 MtCO2-2.26 MtCO2 (-4.5% on average compared to the zero-ECE case). The time-varying ECE is necessary for predicting Japan's electricity demand and CO2 emissions after the earthquake.

Dynamic linear modeling of monthly electricity demand in Japan: Time variation of electricity conservation effect.

Directory of Open Access Journals (Sweden)

Keita Honjo

Full Text Available After the severe nuclear disaster in Fukushima, which was triggered by the Great East Japan earthquake in March 2011, nuclear power plants in Japan were temporarily shut down for mandatory inspections. To prevent large-scale blackouts, the Japanese government requested companies and households to reduce electricity consumption in summer and winter. It is reported that the domestic electricity demand had a structural decrease because of the electricity conservation effect (ECE. However, quantitative analysis of the ECE is not sufficient, and especially time variation of the ECE remains unclear. Understanding the ECE is important because Japan's NDC (nationally determined contribution assumes the reduction of CO2 emissions through aggressive energy conservation. In this study, we develop a time series model of monthly electricity demand in Japan and estimate time variation of the ECE. Moreover, we evaluate the impact of electricity conservation on CO2 emissions from power plants. The dynamic linear model is used to separate the ECE from the effects of other irrelevant factors (e.g. air temperature, economic production, and electricity price. Our result clearly shows that consumers' electricity conservation behavior after the earthquake was not temporary but became established as a habit. Between March 2011 and March 2016, the ECE on industrial electricity demand ranged from 3.9% to 5.4%, and the ECE on residential electricity demand ranged from 1.6% to 7.6%. The ECE on the total electricity demand was estimated at 3.2%-6.0%. We found a seasonal pattern that the residential ECE in summer is higher than that in winter. The emissions increase from the shutdown of nuclear power plants was mitigated by electricity conservation. The emissions reduction effect was estimated at 0.82 MtCO2-2.26 MtCO2 (-4.5% on average compared to the zero-ECE case. The time-varying ECE is necessary for predicting Japan's electricity demand and CO2 emissions after the

Dynamic linear modeling of monthly electricity demand in Japan: Time variation of electricity conservation effect

Science.gov (United States)

Shiraki, Hiroto; Ashina, Shuichi

2018-01-01

After the severe nuclear disaster in Fukushima, which was triggered by the Great East Japan earthquake in March 2011, nuclear power plants in Japan were temporarily shut down for mandatory inspections. To prevent large-scale blackouts, the Japanese government requested companies and households to reduce electricity consumption in summer and winter. It is reported that the domestic electricity demand had a structural decrease because of the electricity conservation effect (ECE). However, quantitative analysis of the ECE is not sufficient, and especially time variation of the ECE remains unclear. Understanding the ECE is important because Japan’s NDC (nationally determined contribution) assumes the reduction of CO2 emissions through aggressive energy conservation. In this study, we develop a time series model of monthly electricity demand in Japan and estimate time variation of the ECE. Moreover, we evaluate the impact of electricity conservation on CO2 emissions from power plants. The dynamic linear model is used to separate the ECE from the effects of other irrelevant factors (e.g. air temperature, economic production, and electricity price). Our result clearly shows that consumers’ electricity conservation behavior after the earthquake was not temporary but became established as a habit. Between March 2011 and March 2016, the ECE on industrial electricity demand ranged from 3.9% to 5.4%, and the ECE on residential electricity demand ranged from 1.6% to 7.6%. The ECE on the total electricity demand was estimated at 3.2%–6.0%. We found a seasonal pattern that the residential ECE in summer is higher than that in winter. The emissions increase from the shutdown of nuclear power plants was mitigated by electricity conservation. The emissions reduction effect was estimated at 0.82 MtCO2–2.26 MtCO2 (−4.5% on average compared to the zero-ECE case). The time-varying ECE is necessary for predicting Japan’s electricity demand and CO2 emissions after the

Time Resolved Digital PIV Measurements of Flow Field Cyclic Variation in an Optical IC Engine

Energy Technology Data Exchange (ETDEWEB)

Jarvis, S; Justham, T; Clarke, A; Garner, C P; Hargrave, G K; Halliwell, N A [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU (United Kingdom)

2006-07-15

Time resolved digital particle image velocimetry (DPIV) experimental data is presented for the in-cylinder flow field development of a motored four stroke spark ignition (SI) optical internal combustion (IC) engine. A high speed DPIV system was employed to quantify the velocity field development during the intake and compression stroke at an engine speed of 1500 rpm. The results map the spatial and temporal development of the in-cylinder flow field structure allowing comparison between traditional ensemble average and cycle average flow field structures. Conclusions are drawn with respect to engine flow field cyclic variations.

Time Resolved Digital PIV Measurements of Flow Field Cyclic Variation in an Optical IC Engine

International Nuclear Information System (INIS)

Jarvis, S; Justham, T; Clarke, A; Garner, C P; Hargrave, G K; Halliwell, N A

2006-01-01

Time resolved digital particle image velocimetry (DPIV) experimental data is presented for the in-cylinder flow field development of a motored four stroke spark ignition (SI) optical internal combustion (IC) engine. A high speed DPIV system was employed to quantify the velocity field development during the intake and compression stroke at an engine speed of 1500 rpm. The results map the spatial and temporal development of the in-cylinder flow field structure allowing comparison between traditional ensemble average and cycle average flow field structures. Conclusions are drawn with respect to engine flow field cyclic variations

Time Resolved Digital PIV Measurements of Flow Field Cyclic Variation in an Optical IC Engine

Science.gov (United States)

Jarvis, S.; Justham, T.; Clarke, A.; Garner, C. P.; Hargrave, G. K.; Halliwell, N. A.

2006-07-01

Time resolved digital particle image velocimetry (DPIV) experimental data is presented for the in-cylinder flow field development of a motored four stroke spark ignition (SI) optical internal combustion (IC) engine. A high speed DPIV system was employed to quantify the velocity field development during the intake and compression stroke at an engine speed of 1500 rpm. The results map the spatial and temporal development of the in-cylinder flow field structure allowing comparison between traditional ensemble average and cycle average flow field structures. Conclusions are drawn with respect to engine flow field cyclic variations.

How universal is the Big Five? Testing the five-factor model of personality variation among forager-farmers in the Bolivian Amazon.

Science.gov (United States)

Gurven, Michael; von Rueden, Christopher; Massenkoff, Maxim; Kaplan, Hillard; Lero Vie, Marino

2013-02-01

The five-factor model (FFM) of personality variation has been replicated across a range of human societies, suggesting the FFM is a human universal. However, most studies of the FFM have been restricted to literate, urban populations, which are uncharacteristic of the majority of human evolutionary history. We present the first test of the FFM in a largely illiterate, indigenous society. Tsimane forager-horticulturalist men and women of Bolivia (n = 632) completed a translation of the 44-item Big Five Inventory (Benet-Martínez & John, 1998), a widely used metric of the FFM. We failed to find robust support for the FFM, based on tests of (a) internal consistency of items expected to segregate into the Big Five factors, (b) response stability of the Big Five, (c) external validity of the Big Five with respect to observed behavior, (d) factor structure according to exploratory and confirmatory factor analysis, and (e) similarity with a U.S. target structure based on Procrustes rotation analysis. Replication of the FFM was not improved in a separate sample of Tsimane adults (n = 430), who evaluated their spouses on the Big Five Inventory. Removal of reverse-scored items that may have elicited response biases produced factors suggestive of Extraversion, Agreeableness, and Conscientiousness, but fit to the FFM remained poor. Response styles may covary with exposure to education, but we found no better fit to the FFM among Tsimane who speak Spanish or have attended school. We argue that Tsimane personality variation displays 2 principal factors that may reflect socioecological characteristics common to small-scale societies. We offer evolutionary perspectives on why the structure of personality variation may not be invariant across human societies. (c) 2013 APA, all rights reserved.

How Universal Is the Big Five? Testing the Five-Factor Model of Personality Variation Among Forager–Farmers in the Bolivian Amazon

Science.gov (United States)

Gurven, Michael; von Rueden, Christopher; Massenkoff, Maxim; Kaplan, Hillard; Vie, Marino Lero

2014-01-01

The five-factor model (FFM) of personality variation has been replicated across a range of human societies, suggesting the FFM is a human universal. However, most studies of the FFM have been restricted to literate, urban populations, which are uncharacteristic of the majority of human evolutionary history. We present the first test of the FFM in a largely illiterate, indigenous society. Tsimane forager–horticulturalist men and women of Bolivia (n = 632) completed a translation of the 44-item Big Five Inventory (Benet-Martínez & John, 1998), a widely used metric of the FFM. We failed to find robust support for the FFM, based on tests of (a) internal consistency of items expected to segregate into the Big Five factors, (b) response stability of the Big Five, (c) external validity of the Big Five with respect to observed behavior, (d) factor structure according to exploratory and confirmatory factor analysis, and (e) similarity with a U.S. target structure based on Procrustes rotation analysis. Replication of the FFM was not improved in a separate sample of Tsimane adults (n = 430), who evaluated their spouses on the Big Five Inventory. Removal of reverse-scored items that may have elicited response biases produced factors suggestive of Extraversion, Agreeableness, and Conscientiousness, but fit to the FFM remained poor. Response styles may covary with exposure to education, but we found no better fit to the FFM among Tsimane who speak Spanish or have attended school. We argue that Tsimane personality variation displays 2 principal factors that may reflect socioecological characteristics common to small-scale societies. We offer evolutionary perspectives on why the structure of personality variation may not be invariant across human societies. PMID:23245291

Human language reveals a universal positivity bias.

Science.gov (United States)

Dodds, Peter Sheridan; Clark, Eric M; Desu, Suma; Frank, Morgan R; Reagan, Andrew J; Williams, Jake Ryland; Mitchell, Lewis; Harris, Kameron Decker; Kloumann, Isabel M; Bagrow, James P; Megerdoomian, Karine; McMahon, Matthew T; Tivnan, Brian F; Danforth, Christopher M

2015-02-24

Using human evaluation of 100,000 words spread across 24 corpora in 10 languages diverse in origin and culture, we present evidence of a deep imprint of human sociality in language, observing that (i) the words of natural human language possess a universal positivity bias, (ii) the estimated emotional content of words is consistent between languages under translation, and (iii) this positivity bias is strongly independent of frequency of word use. Alongside these general regularities, we describe interlanguage variations in the emotional spectrum of languages that allow us to rank corpora. We also show how our word evaluations can be used to construct physical-like instruments for both real-time and offline measurement of the emotional content of large-scale texts.

TRANSIT TIMING VARIATIONS FOR INCLINED AND RETROGRADE EXOPLANETARY SYSTEMS

International Nuclear Information System (INIS)

Payne, Matthew J.; Ford, Eric B.; Veras, Dimitri

2010-01-01

We perform numerical calculations of the expected transit timing variations (TTVs) induced on a hot-Jupiter by an Earth-mass perturber. Motivated by the recent discoveries of retrograde transiting planets, we concentrate on an investigation of the effect of varying relative planetary inclinations, up to and including completely retrograde systems. We find that planets in low-order (e.g., 2:1) mean-motion resonances (MMRs) retain approximately constant TTV amplitudes for 0 deg. 170 deg. Systems in higher order MMRs (e.g., 5:1) increase in TTV amplitude as inclinations increase toward 45 deg., becoming approximately constant for 45 deg. 135 deg. Planets away from resonance slowly decrease in TTV amplitude as inclinations increase from 0 deg. to 180 deg., whereas planets adjacent to resonances can exhibit a huge range of variability in TTV amplitude as a function of both eccentricity and inclination. For highly retrograde systems (135 deg. < i ≤ 180 deg.), TTV signals will be undetectable across almost the entirety of parameter space, with the exceptions occurring when the perturber has high eccentricity or is very close to an MMR. This high inclination decrease in TTV amplitude (on and away from resonance) is important for the analysis of the known retrograde and multi-planet transiting systems, as inclination effects need to be considered if TTVs are to be used to exclude the presence of any putative planetary companions: absence of evidence is not evidence of absence.

Foreign language classroom anxiety : A study of Chinese university students of Japanese and English over time

NARCIS (Netherlands)

Jin, Yinxing

2016-01-01

This PhD project mainly aimed at exploring the relationship between foreign language (FL) anxiety and FL proficiency development, the sources of FL anxiety, and the stability of FL anxiety over time and across target languages. To this end, 146 L1 Chinese university students, who had been learning

Optimal time travel in the Godel universe

OpenAIRE

Natario, Jose

2011-01-01

Using the theory of optimal rocket trajectories in general relativity, recently developed in arXiv:1105.5235, we present a candidate for the minimum total integrated acceleration closed timelike curve in the Godel universe, and give evidence for its minimality. The total integrated acceleration of this curve is lower than Malament's conjectured value (Malament, 1984), as was already implicit in the work of Manchak (Manchak, 2011); however, Malament's conjecture does seem to hold for periodic ...

Densities and eccentricities of 139 Kepler planets from transit time variations

Energy Technology Data Exchange (ETDEWEB)

Hadden, Sam; Lithwick, Yoram [Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States)

2014-05-20

We extract densities and eccentricities of 139 sub-Jovian planets by analyzing transit time variations (TTVs) obtained by the Kepler mission through Quarter 12. We partially circumvent the degeneracies that plague TTV inversion with the help of an analytical formula for the TTV. From the observed TTV phases, we find that most of these planets have eccentricities of the order of a few percent. More precisely, the rms eccentricity is 0.018{sub −0.004}{sup +0.005}, and planets smaller than 2.5 R {sub ⊕} are around twice as eccentric as those bigger than 2.5 R {sub ⊕}. We also find a best-fit density-radius relationship ρ ≈ 3 g cm{sup –3} × (R/3 R {sub ⊕}){sup –2.3} for the 56 planets that likely have small eccentricity and hence small statistical correction to their masses. Many planets larger than 2.5 R {sub ⊕} are less dense than water, implying that their radii are largely set by a massive hydrogen atmosphere.

Real-Time Climate Simulations in the Interactive 3D Game Universe Sandbox ²

Science.gov (United States)

Goldenson, N. L.

2014-12-01

Exploration in an open-ended computer game is an engaging way to explore climate and climate change. Everyone can explore physical models with real-time visualization in the educational simulator Universe Sandbox ² (universesandbox.com/2), which includes basic climate simulations on planets. I have implemented a time-dependent, one-dimensional meridional heat transport energy balance model to run and be adjustable in real time in the midst of a larger simulated system. Universe Sandbox ² is based on the original game - at its core a gravity simulator - with other new physically-based content for stellar evolution, and handling collisions between bodies. Existing users are mostly science enthusiasts in informal settings. We believe that this is the first climate simulation to be implemented in a professionally developed computer game with modern 3D graphical output in real time. The type of simple climate model we've adopted helps us depict the seasonal cycle and the more drastic changes that come from changing the orbit or other external forcings. Users can alter the climate as the simulation is running by altering the star(s) in the simulation, dragging to change orbits and obliquity, adjusting the climate simulation parameters directly or changing other properties like CO2 concentration that affect the model parameters in representative ways. Ongoing visuals of the expansion and contraction of sea ice and snow-cover respond to the temperature calculations, and make it accessible to explore a variety of scenarios and intuitive to understand the output. Variables like temperature can also be graphed in real time. We balance computational constraints with the ability to capture the physical phenomena we wish to visualize, giving everyone access to a simple open-ended meridional energy balance climate simulation to explore and experiment with. The software lends itself to labs at a variety of levels about climate concepts including seasons, the Greenhouse effect

Developmental plasticity in Tenebrio molitor (Coleoptera: Tenebrionidae): Analysis of Instar Variation in Number and Development Time under Different Diets

Science.gov (United States)

The variation in instar number and the pattern of sequential instar development time of Tenebrio molitor L. (Coleoptera: Tenebrionidae) was studied under 4 different diet regimes. Addition of dietary supplements consisting of dry potato or a mix of dry potato and dry egg whites significantly reduced...

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.

Fast-time Variations of Supernova Neutrino Fluxes and Detection Perspectives

NARCIS (Netherlands)

Tamborra, I.; Hanke, F.; Müller, B.; Janka, H.T.; Raffelt, G.G.

2015-01-01

In the delayed explosion scenario of a core-collapse supernova, the accretion phase shows pronounced convective over-turns and a low-multipole hydrodynamic instability, the so-called standing accretion shock instability (SASI). Neutrino signal variations from the first full-scale three-dimensional

Nonlinear forecasts of ƒoF2: variation of model predictive accuracy over time

Directory of Open Access Journals (Sweden)

P. S. Cannon

Full Text Available Space weather effects can strongly influence high-frequency (HF communications by changing the ionospheric environment through which the radio waves propagate. Since many systems utilize HF communications, the ability to make real-time assessments of propagation conditions is an important part of space weather monitoring systems. In this paper, we present new techniques for measuring high-latitude HF communications link parameters using data from SuperDARN radars. These techniques use ground-scatter returns to define the variation in skip distance with frequency. From these data, the maximum usable frequency (MUF as a function of range is determined and ionospheric critical frequencies are estimated. These calculations are made in near-real-time and the results are made available on the World Wide Web. F-region critical frequencies calculated using this method show good agreement with ionosonde data.Key words. Ionosphere (active experiments; instruments and techniques – Radio science (ionospheric propagation

Nonlinear forecasts of ƒoF2: variation of model predictive accuracy over time

Directory of Open Access Journals (Sweden)

A. H. Y. Chan

2002-07-01

Full Text Available Space weather effects can strongly influence high-frequency (HF communications by changing the ionospheric environment through which the radio waves propagate. Since many systems utilize HF communications, the ability to make real-time assessments of propagation conditions is an important part of space weather monitoring systems. In this paper, we present new techniques for measuring high-latitude HF communications link parameters using data from SuperDARN radars. These techniques use ground-scatter returns to define the variation in skip distance with frequency. From these data, the maximum usable frequency (MUF as a function of range is determined and ionospheric critical frequencies are estimated. These calculations are made in near-real-time and the results are made available on the World Wide Web. F-region critical frequencies calculated using this method show good agreement with ionosonde data.Key words. Ionosphere (active experiments; instruments and techniques – Radio science (ionospheric propagation

Assessment of operative times of multiple surgical specialties in a public university hospital.

Science.gov (United States)

Costa, Altair da Silva

2017-01-01

To evaluate the indicators duration of anesthesia, operative time and time patients stay in the operating rooms of different surgical specialties at a public university hospital. It was done by a descriptive cross-sectional study based on the operating room database. The following stages were measured: duration of anesthesia, procedure time and patient length of stay in the room of the various specialties. We included surgeries carried out in sequence in the same room, between 7:00 a.m. and 5 p.m., either elective or emergency. We calculated the 80th percentile of the stages, where 80% of procedures were below this value. The study measured 8,337 operations of 12 surgical specialties performed within one year. The overall mean duration of anesthesia of all specialties was 178.12±110.46 minutes, and the 80th percentile was 252 minutes. The mean operative time was 130.45±97.23 minutes, and the 80th percentile was 195 minutes. The mean total time of the patient in the operating room was 197.30±113.71 minutes, and the 80th percentile was 285 minutes. Thus, the variation of the overall mean compared to the 80th percentile was 41% for anesthesia, 49% for surgeries and 44% for operating room time. In average, anesthesia took up 88% of the operating room period, and surgery, 61%. This study identified patterns in the duration of surgery stages. The mean values of the specialties can assist with operating room planning and reduce delays. Avaliar os indicadores de tempo da anestesia, da operação e da permanência do paciente em sala de diversas especialidades do centro cirúrgico de um hospital universitário. Foi realizado em estudo descritivo transversal a partir da base de dados do centro cirúrgico e mensuradas as seguintes etapas: duração de anestesia, tempo do procedimento e tempo de permanência do paciente em sala das diversas especialidades. Foram incluídas as operações realizadas em sequência na mesma sala, das 7h às 17h, eletivas ou de urg

Variational divergence in wave scattering theory with Kirchhoffean trial functions

Science.gov (United States)

Bird, J. F.

1986-01-01

In a recent study of variational improvement of the Kirchhoff approximation for electromagnetic scattering by rough surfaces, a key ingredient in the variational principle was found to diverge for important configurations (e.g., backscatter) if the polarization had any vertical component. The cause and a cure of this divergence are discussed here. The divergence is demonstrated to occur for arbitrary perfectly conducting scatterers and its universal characterstics are determined, by means of a general divergence criterion that is derived. A variational cure for the divergence is prescribed, and it is tested successfully on a standard scattering model.

Cordova: web-based management of genetic variation data.

Science.gov (United States)

Ephraim, Sean S; Anand, Nikhil; DeLuca, Adam P; Taylor, Kyle R; Kolbe, Diana L; Simpson, Allen C; Azaiez, Hela; Sloan, Christina M; Shearer, A Eliot; Hallier, Andrea R; Casavant, Thomas L; Scheetz, Todd E; Smith, Richard J H; Braun, Terry A

2014-12-01

Cordova is an out-of-the-box solution for building and maintaining an online database of genetic variations integrated with pathogenicity prediction results from popular algorithms. Our primary motivation for developing this system is to aid researchers and clinician-scientists in determining the clinical significance of genetic variations. To achieve this goal, Cordova provides an interface to review and manually or computationally curate genetic variation data as well as share it for clinical diagnostics and the advancement of research. Cordova is open source under the MIT license and is freely available for download at https://github.com/clcg/cordova. Published by Oxford University Press. This work is written by US Government employees and is in the public domain in the US.

Assessment of spatio-temporal variations in surface water quality of ...

African Journals Online (AJOL)

MANN

2012-10-02

Oct 2, 2012 ... 1School of Biological and Environmental Sciences, Shoolini University, Solan, H.P.- 173229, India. 2Department ... variation. Of late, multivariate statistical techniques such ..... Statistical Package for the Social Sciences 10.0.

Fetal short time variation during labor: a non-invasive alternative to fetal scalp pH measurements?

OpenAIRE

Schiermeier, Sven; Reinhard, Joscha; Hatzmann, Hendrike; Zimmermann, Ralf C.; Westhof, Gregor

2009-01-01

Objective: To determine whether short time variation (STV) of fetal heart beat correlates with scalp pH measurements during labor. Patients and methods: From 1279 deliveries, 197 women had at least one fetal scalp pH measurement. Using the CTG-Player®, STVs were calculated from the electronically saved cardiotocography (CTG) traces and related to the fetal scalp pH measurements. Results: There was no correlation between STV and fetal scalp pH measurements (r=−0.0592). Conclusions: Fetal ST...

Intrapopulation genome size variation in D. melanogaster reflects life history variation and plasticity.

Directory of Open Access Journals (Sweden)

Lisa L Ellis

2014-07-01

Full Text Available We determined female genome sizes using flow cytometry for 211 Drosophila melanogaster sequenced inbred strains from the Drosophila Genetic Reference Panel, and found significant conspecific and intrapopulation variation in genome size. We also compared several life history traits for 25 lines with large and 25 lines with small genomes in three thermal environments, and found that genome size as well as genome size by temperature interactions significantly correlated with survival to pupation and adulthood, time to pupation, female pupal mass, and female eclosion rates. Genome size accounted for up to 23% of the variation in developmental phenotypes, but the contribution of genome size to variation in life history traits was plastic and varied according to the thermal environment. Expression data implicate differences in metabolism that correspond to genome size variation. These results indicate that significant genome size variation exists within D. melanogaster and this variation may impact the evolutionary ecology of the species. Genome size variation accounts for a significant portion of life history variation in an environmentally dependent manner, suggesting that potential fitness effects associated with genome size variation also depend on environmental conditions.

Intrapopulation Genome Size Variation in D. melanogaster Reflects Life History Variation and Plasticity

Science.gov (United States)

Ellis, Lisa L.; Huang, Wen; Quinn, Andrew M.; Ahuja, Astha; Alfrejd, Ben; Gomez, Francisco E.; Hjelmen, Carl E.; Moore, Kristi L.; Mackay, Trudy F. C.; Johnston, J. Spencer; Tarone, Aaron M.

2014-01-01

We determined female genome sizes using flow cytometry for 211 Drosophila melanogaster sequenced inbred strains from the Drosophila Genetic Reference Panel, and found significant conspecific and intrapopulation variation in genome size. We also compared several life history traits for 25 lines with large and 25 lines with small genomes in three thermal environments, and found that genome size as well as genome size by temperature interactions significantly correlated with survival to pupation and adulthood, time to pupation, female pupal mass, and female eclosion rates. Genome size accounted for up to 23% of the variation in developmental phenotypes, but the contribution of genome size to variation in life history traits was plastic and varied according to the thermal environment. Expression data implicate differences in metabolism that correspond to genome size variation. These results indicate that significant genome size variation exists within D. melanogaster and this variation may impact the evolutionary ecology of the species. Genome size variation accounts for a significant portion of life history variation in an environmentally dependent manner, suggesting that potential fitness effects associated with genome size variation also depend on environmental conditions. PMID:25057905

NO TIMING VARIATIONS OBSERVED IN THIRD TRANSIT OF SNOW-LINE EXOPLANET KEPLER-421b

International Nuclear Information System (INIS)

Dalba, Paul A.; Muirhead, Philip S.

2016-01-01

We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler spacecraft only observed two transits of Kepler-421b, leaving the planet’s transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3 m Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b, barring significant TTVs. We use the light curves to assess the probabilities of various transit models using both the posterior odds ratio and the Bayesian Information Criterion, and find that a transit model with no TTVs is favored to 3.6 σ confidence. These observations suggest that Kepler-421b is either alone in its system or is only experiencing minor dynamic interactions with an unseen companion. With the Kepler-421b ephemeris constrained, we calculate future transit times and discuss the opportunity to characterize the atmosphere of this cold, long-period exoplanet via transmission spectroscopy. Our investigation emphasizes the difficulties associated with observing long-period exoplanet transits and the consequences that arise from failing to refine transit ephemerides.

Transit Timing Variation analysis with Kepler light curves of KOI 227 and Kepler 93b

Science.gov (United States)

Dulz, Shannon; Reed, Mike

2017-01-01

By searching for transit signals in approximately 150,000 stars, NASA’s Kepler Space telescope found thousands of exoplanets over its primary mission from 2009 to 2013 (Tenenbaum et al. 2014, ApJS, 211, 6). Yet, a detailed follow-up examination of Kepler light curves may contribute more evidence on system dynamics and planetary atmospheres of these objects. Kepler’s continuous observing of these systems over the mission duration produced light curves of sufficient duration to allow for the search for transit timing variations. Transit timing variations over the course of many orbits may indicate a precessing orbit or the existence of a non-transiting third body such as another exoplanet. Flux contributions of the planet just prior to secondary eclipse may provide a measurement of bond albedo from the day-side of the transiting planet. Any asymmetries of the transit shape may indicate thermal asymmetries which can measure upper atmosphere motion of the planet. These two factors can constrain atmospheric models of close orbiting exoplanets. We first establish our procedure with the well-documented TTV system, KOI 227 (Nesvorny et al. 2014, ApJ, 790, 31). Using the test case of KOI 227, we analyze Kepler-93b for TTVs and day-side flux contributions. Kepler-93b is likely a rocky planet with R = 1.50 ± 0.03 Earth Radii and M = 2.59 ± 2.0 Earth Masses (Marcy et al. 2014, ApJS, 210, 20). This research is funded by a NASA EPSCoR grant.

Prezygotic barriers to hybridization in marine broadcast spawners: reproductive timing and mating system variation.

Directory of Open Access Journals (Sweden)

Carla A Monteiro

Full Text Available Sympatric assemblages of congeners with incomplete reproductive barriers offer the opportunity to study the roles that ecological and non-ecological factors play in reproductive isolation. While interspecific asynchrony in gamete release and gametic incompatibility are known prezygotic barriers to hybridization, the role of mating system variation has been emphasized in plants. Reproductive isolation between the sibling brown algal species Fucus spiralis, Fucus guiryi (selfing hermaphrodite and Fucus vesiculosus (dioecious was studied because they form hybrids in parapatry in the rocky intertidal zone, maintain species integrity over a broad geographic range, and have contrasting mating systems. We compared reproductive synchrony (spawning overlap between the three species at several temporal scales (yearly/seasonal, semilunar/tidal, and hourly during single tides. Interspecific patterns of egg release were coincident at seasonal (single peak in spring to early summer to semilunar timescales. Synthesis of available data indicated that spawning is controlled by semidiurnal tidal and daily light-dark cues, and not directly by semilunar cycles. Importantly, interspecific shifts in timing detected at the hourly scale during single tides were consistent with a partial ecological prezygotic hybridization barrier. The species displayed patterns of gamete release consistent with a power law distribution, indicating a high degree of reproductive synchrony, while the hypothesis of weaker selective constraints for synchrony in selfing versus outcrossing species was supported by observed spawning in hermaphrodites over a broader range of tidal phase than in outcrossers. Synchronous gamete release is critical to the success of external fertilization, while high-energy intertidal environments may offer only limited windows of reproductive opportunity. Within these windows, however, subtle variations in reproductive timing have evolved with the potential to

Academics as Part-Time Marketers in University Offshore Programs: An Exploratory Study

Science.gov (United States)

Poole, David; Ewan, Craig

2010-01-01

Australian universities maintain almost 900 offshore programs delivered to more than 100 000 students, primarily in the nations of Singapore, Malaysia, China, and Hong Kong (Universities Australia, 2009; IDP, 2009a). Although offshore students comprise an estimated 30 per cent of international student enrolments at Australian universities (IDP,…

Scientists develop the Universe's baby pictures

CERN Multimedia

Overbye, D

2002-01-01

Using a radio telescope high in the Andes, astronomers have mapped minute variations in the brightness of radio waves thought to be left over from the Big Bang. They reveal the universe when it was only some 300,000 years old and about as hot as a cool star (2 pages).

Relaxation time of normal breast tissues. Changes with age and variations during the menstrual cycle

International Nuclear Information System (INIS)

Dean, K.I.; Majurin, M.L.; Komu, M.

1994-01-01

The influence of age on the relaxation times of normal breast parenchyma and its surrounding fatty tissue were evaluated, and the variations during a normal menstrual cycle were analyzed using an ultra low field 0.02 T imager. Thirty-nine healthy volunteers aged 21 to 59 years were examined to determine T1 and T2 relaxation times, and 8 of these volunteers were studied once weekly during one menstrual cycle. The only significant trend was an increase in the T2 of breast parenchyma with increasing age. During the menstrual cycle there was a slight but insignificant (p=0.10) increase in T1 of the breast parenchyma values during the latter half of the menstrual cycle, and a corresponding increase in T2 values between the 2nd and 3rd weeks of the menstrual cycle, which was significant. (orig.)

Relaxation time of normal breast tissues. Changes with age and variations during the menstrual cycle

Energy Technology Data Exchange (ETDEWEB)

Dean, K.I. (University Central Hospital, Turku (Finland). Dept. of Diagnostic Radiology); Majurin, M.L. (University Central Hospital, Turku (Finland). Dept. of Diagnostic Radiology); Komu, M. (University Central Hospital, Turku (Finland). Dept. of Diagnostic Radiology)

1994-05-01

The influence of age on the relaxation times of normal breast parenchyma and its surrounding fatty tissue were evaluated, and the variations during a normal menstrual cycle were analyzed using an ultra low field 0.02 T imager. Thirty-nine healthy volunteers aged 21 to 59 years were examined to determine T1 and T2 relaxation times, and 8 of these volunteers were studied once weekly during one menstrual cycle. The only significant trend was an increase in the T2 of breast parenchyma with increasing age. During the menstrual cycle there was a slight but insignificant (p=0.10) increase in T1 of the breast parenchyma values during the latter half of the menstrual cycle, and a corresponding increase in T2 values between the 2nd and 3rd weeks of the menstrual cycle, which was significant. (orig.).

The circadian variation of premature atrial contractions

DEFF Research Database (Denmark)

Larsen, Bjørn Strøier; Kumarathurai, Preman; Nielsen, Olav W

2016-01-01

AIMS: The aim of the study was to assess a possible circadian variation of premature atrial contractions (PACs) in a community-based population and to determine if the daily variation could be used to assess a more vulnerable period of PACs in predicting later incidence of atrial fibrillation (AF...... variation in heart rate. After adjusting for relevant risk factors, the risk of AF was equal in all time intervals throughout the day. CONCLUSION: Premature atrial contractions showed a circadian variation in subjects with frequent PACs. No specific time interval of the day was more predictive of AF than...

Interpreting the universal phylogenetic tree

Science.gov (United States)

Woese, C. R.

2000-01-01

The universal phylogenetic tree not only spans all extant life, but its root and earliest branchings represent stages in the evolutionary process before modern cell types had come into being. The evolution of the cell is an interplay between vertically derived and horizontally acquired variation. Primitive cellular entities were necessarily simpler and more modular in design than are modern cells. Consequently, horizontal gene transfer early on was pervasive, dominating the evolutionary dynamic. The root of the universal phylogenetic tree represents the first stage in cellular evolution when the evolving cell became sufficiently integrated and stable to the erosive effects of horizontal gene transfer that true organismal lineages could exist.

Determinants of Awareness, Consideration, and Choice Set Size in University Choice.

Science.gov (United States)

Dawes, Philip L.; Brown, Jennifer

2002-01-01

Developed and tested a model of students' university "brand" choice using five individual-level variables (ethnic group, age, gender, number of parents going to university, and academic ability) and one situational variable (duration of search) to explain variation in the sizes of awareness, consideration, and choice decision sets. (EV)

A search for transit timing variations and orbital decay in WASP-46b

Science.gov (United States)

Petrucci, R.; Jofré, E.; Ferrero, L. V.; Cúneo, V.; Saker, L.; Lovos, F.; Gómez, M.; Mauas, P.

2018-02-01

We present 12 new transit observations of the exoplanet WASP-46b obtained with the 1.54-m telescope at Estación Astrofísica de Bosque Alegre (EABA, Argentina) and the 0.40-m Horacio Ghielmetti and 2.15-m Jorge Sahade telescopes at Complejo Astronómico El Leoncito (CASLEO, Argentina). We analyse them together with 37 light curves from the literature to re-determine the physical parameters and search for additional planets via transit timing variations (TTVs). We consider the 31 transits with uncertainties in their mid-transit times (e_T0) activity could be affecting the measured mid-transit times. This value of dispersion allows us to rule out the presence of additional bodies with masses larger than 2.3, 4.6, 7 and 9.3 M_{\\oplus} at the first-order mean-motion resonances 2:1, 3:2, 4:3 and 5:4 with the transiting planet, respectively. Despite the 6 yr baseline and a typical light-curve precision of 2 × 10-3, we find that we cannot significantly demonstrate a slow decrease of the orbital period of WASP-46b. We place a lower limit of Q⋆ > 7 × 103 on the tidal quality factor and determine that an additional 6 yr baseline is required to rule out Q⋆ < 105.

On minimizers of causal variational principles

International Nuclear Information System (INIS)

Schiefeneder, Daniela

2011-01-01

Causal variational principles are a class of nonlinear minimization problems which arise in a formulation of relativistic quantum theory referred to as the fermionic projector approach. This thesis is devoted to a numerical and analytic study of the minimizers of a general class of causal variational principles. We begin with a numerical investigation of variational principles for the fermionic projector in discrete space-time. It is shown that for sufficiently many space-time points, the minimizing fermionic projector induces non-trivial causal relations on the space-time points. We then generalize the setting by introducing a class of causal variational principles for measures on a compact manifold. In our main result we prove under general assumptions that the support of a minimizing measure is either completely timelike, or it is singular in the sense that its interior is empty. In the examples of the circle, the sphere and certain flag manifolds, the general results are supplemented by a more detailed analysis of the minimizers. (orig.)

Variational Algorithms for Test Particle Trajectories

Science.gov (United States)

Ellison, C. Leland; Finn, John M.; Qin, Hong; Tang, William M.

2015-11-01

The theory of variational integration provides a novel framework for constructing conservative numerical methods for magnetized test particle dynamics. The retention of conservation laws in the numerical time advance captures the correct qualitative behavior of the long time dynamics. For modeling the Lorentz force system, new variational integrators have been developed that are both symplectic and electromagnetically gauge invariant. For guiding center test particle dynamics, discretization of the phase-space action principle yields multistep variational algorithms, in general. Obtaining the desired long-term numerical fidelity requires mitigation of the multistep method's parasitic modes or applying a discretization scheme that possesses a discrete degeneracy to yield a one-step method. Dissipative effects may be modeled using Lagrange-D'Alembert variational principles. Numerical results will be presented using a new numerical platform that interfaces with popular equilibrium codes and utilizes parallel hardware to achieve reduced times to solution. This work was supported by DOE Contract DE-AC02-09CH11466.

Perfectionistic Cognitions: Stability, Variability, and Changes Over Time.

Science.gov (United States)

Prestele, Elisabeth; Altstötter-Gleich, Christine

2018-02-01

The construct of perfectionistic cognitions is defined as a state-like construct resulting from a perfectionistic self-schema and activated by specific situational demands. Only a few studies have investigated whether and how perfectionistic cognitions change across different situations and whether they reflect stable between-person differences or also within-person variations over time. We conducted 2 studies to investigate the variability and stability of 3 dimensions of perfectionistic cognitions while situational demands changed (Study 1) and on a daily level during a highly demanding period of time (Study 2). The results of both studies revealed that stable between-person differences accounted for the largest proportion of variance in the dimensions of perfectionistic cognitions and that these differences were validly associated with between-person differences in affect. The frequency of perfectionistic cognitions increased during students' first semester at university, and these average within-person changes were different for the 3 dimensions of perfectionistic cognitions (Study 1). In addition, there were between-person differences in the within-person changes that were validly associated with concurrent changes in closely related constructs (unpleasant mood and tense arousal). Within-person variations in perfectionistic cognitions were also validly associated with variations in unpleasant mood and tense arousal from day to day (Study 2).

Chinese L1 children's English L2 verb morphology over time: individual variation in long-term outcomes.

Science.gov (United States)

Paradis, Johanne; Tulpar, Yasemin; Arppe, Antti

2016-05-01

This study examined accuracy in production and grammaticality judgements of verb morphology by eighteen Chinese-speaking children learning English as a second language (L2) followed longitudinally from four to six years of exposure to English, and who began to learn English at age 4;2. Children's growth in accuracy with verb morphology reached a plateau by six years, where 11/18 children did not display native-speaker levels of accuracy for one or more morphemes. Variation in children's accuracy with verb morphology was predicted by their English vocabulary size and verbal short-term memories primarily, and quality and quantity of English input at home secondarily. This study shows that even very young L2 learners might not all catch up to native speakers in this time frame and that non-age factors play a role in determining individual variation in child L2 learners' long-term outcomes with English morphology.

Real T1 relaxation time measurement and diurnal variation analysis of intervertebral discs in a healthy population of 50 volunteers

International Nuclear Information System (INIS)

Galley, J.; Maestretti, G.; Koch, G.; Hoogewoud, H-M.

2017-01-01

Purpose: To measure the real T1 relaxation time of the lumbar intervertebral discs in a young and healthy population, using different inversion recovery times, and assess diurnal variation. Material and methods: Intervertebral discs from D12 to S1 of 50 healthy volunteers from 18 to 25 years old were evaluated twice the same day, in the morning and in the late afternoon. Dedicated MRI sequences with different inversion recovery times (from 100 to 2500 ms) were used to calculate the real T1 relaxation time. Three regions of interest (ROIs) were defined in each disc, the middle representing the nucleus pulposus (NP) and the outer parts the annulus fibrosus (AF) anterior and posterior. Diurnal variation and differences between each disc level were analyzed. Results: T1 mean values in the NP were 1142 ± 12 ms in the morning and 1085 ± 13 ms in the afternoon, showing a highly significant decrease of 57 ms (p < 0.001). A highly significant difference between the levels of the spine was found. The mean T1 of the anterior part of the AF was 577 ± 9 ms in the morning and 554 ± 8 ms in the afternoon. For the posterior part, the mean values were 633 ± 8 ms in the morning and 581 ± 7 ms in the evening. It shows a highly significant decrease of 23 ms for the anterior part and 51 ms for the posterior part (all p < 0.001). Conclusion: T1 mapping is a promising method of intervertebral disc evaluation. Significant diurnal variation and difference between levels of the lumbar spine were demonstrated. A potential use for longitudinal study in post-operative follow up or sport medicine needs to be evaluated.

Real T1 relaxation time measurement and diurnal variation analysis of intervertebral discs in a healthy population of 50 volunteers

Energy Technology Data Exchange (ETDEWEB)

Galley, J., E-mail: galleyjulien@gmail.com [Department of Radiology, HFR Fribourg, Hôpital Cantonal (Switzerland); Maestretti, G. [Department of Orthopedic Surgery, HFR Fribourg, Hôpital Cantonal (Switzerland); Koch, G.; Hoogewoud, H-M. [Department of Radiology, HFR Fribourg, Hôpital Cantonal (Switzerland)

2017-02-15

Purpose: To measure the real T1 relaxation time of the lumbar intervertebral discs in a young and healthy population, using different inversion recovery times, and assess diurnal variation. Material and methods: Intervertebral discs from D12 to S1 of 50 healthy volunteers from 18 to 25 years old were evaluated twice the same day, in the morning and in the late afternoon. Dedicated MRI sequences with different inversion recovery times (from 100 to 2500 ms) were used to calculate the real T1 relaxation time. Three regions of interest (ROIs) were defined in each disc, the middle representing the nucleus pulposus (NP) and the outer parts the annulus fibrosus (AF) anterior and posterior. Diurnal variation and differences between each disc level were analyzed. Results: T1 mean values in the NP were 1142 ± 12 ms in the morning and 1085 ± 13 ms in the afternoon, showing a highly significant decrease of 57 ms (p < 0.001). A highly significant difference between the levels of the spine was found. The mean T1 of the anterior part of the AF was 577 ± 9 ms in the morning and 554 ± 8 ms in the afternoon. For the posterior part, the mean values were 633 ± 8 ms in the morning and 581 ± 7 ms in the evening. It shows a highly significant decrease of 23 ms for the anterior part and 51 ms for the posterior part (all p < 0.001). Conclusion: T1 mapping is a promising method of intervertebral disc evaluation. Significant diurnal variation and difference between levels of the lumbar spine were demonstrated. A potential use for longitudinal study in post-operative follow up or sport medicine needs to be evaluated.

Joint inversion of shear wave travel time residuals and geoid and depth anomalies for long-wavelength variations in upper mantle temperature and composition along the Mid-Atlantic Ridge

Science.gov (United States)

Sheehan, Anne F.; Solomon, Sean C.

1991-01-01

Measurements were carried out for SS-S differential travel time residuals for nearly 500 paths crossing the northern Mid-Atlantic Ridge, assuming that the residuals are dominated by contributions from the upper mantle near the surface bounce point of the reflected phase SS. Results indicate that the SS-S travel time residuals decrease linearly with square root of age, to an age of 80-100 Ma, in general agreement with the plate cooling model. A joint inversion was formulated of travel time residuals and geoid and bathymetric anomalies for lateral variation in the upper mantle temperature and composition. The preferred inversion solutions were found to have variations in upper mantle temperature along the Mid-Atlantic Ridge of about 100 K. It was calculated that, for a constant bulk composition, such a temperature variation would produce about a 7-km variation in crustal thickness, larger than is generally observed.

The Relationship between the Development of Time and Effort Management and Experiences of the Teaching-Learning Environment in a University Context

Science.gov (United States)

Parpala, Anna; Asikainen, Henna; Ruohoniemi, Mirja; Lindblom-Ylänne, Sari

2017-01-01

Time and effort management skills have proved to be very important in studying, as they provide a foundation for both study success and engagement in university studies across the world. The paper focuses on how these skills develop during university studies in veterinary medicine, and examines possible changes in relation to students' experiences…

The University's Statement of Goals. An Idea Whose Time Has Arrived.

Science.gov (United States)

McKelvie, Brenda D.

1986-01-01

The need for colleges and universities to clarify goals in light of current financial constraints is discussed. The goal formulation strategies and techniques of the Institutional Goals Inventory and the Dephi technique are examined in the context of their application at the University of Ottawa. (MSE)

Unitary Dynamics of Strongly Interacting Bose Gases with the Time-Dependent Variational Monte Carlo Method in Continuous Space

Science.gov (United States)

Carleo, Giuseppe; Cevolani, Lorenzo; Sanchez-Palencia, Laurent; Holzmann, Markus

2017-07-01

We introduce the time-dependent variational Monte Carlo method for continuous-space Bose gases. Our approach is based on the systematic expansion of the many-body wave function in terms of multibody correlations and is essentially exact up to adaptive truncation. The method is benchmarked by comparison to an exact Bethe ansatz or existing numerical results for the integrable Lieb-Liniger model. We first show that the many-body wave function achieves high precision for ground-state properties, including energy and first-order as well as second-order correlation functions. Then, we study the out-of-equilibrium, unitary dynamics induced by a quantum quench in the interaction strength. Our time-dependent variational Monte Carlo results are benchmarked by comparison to exact Bethe ansatz results available for a small number of particles, and are also compared to quench action results available for noninteracting initial states. Moreover, our approach allows us to study large particle numbers and general quench protocols, previously inaccessible beyond the mean-field level. Our results suggest that it is possible to find correlated initial states for which the long-term dynamics of local density fluctuations is close to the predictions of a simple Boltzmann ensemble.

Eating behaviour of university students in Germany: Dietary intake, barriers to healthy eating and changes in eating behaviour since the time of matriculation.

Science.gov (United States)

Hilger, Jennifer; Loerbroks, Adrian; Diehl, Katharina

2017-02-01

A healthy diet plays a key role in preventing obesity and non-communicable diseases such as type 2 diabetes. This is true for all age groups, including young adults. While unhealthy eating habits among young adults, in particular university students, have been identified in former studies, this group has been neglected in existing health promotion strategies. Our aim was to explore baseline dietary intake, common barriers to healthy eating, and changes in eating behaviour among university students since the time of matriculation. We used data from the quantitative part of the Nutrition and Physical Activity Study (NuPhA), a cross-sectional online survey (data collection: 2014/10/31-2015/01/15). Students were recruited from all over Germany. Overall, 689 university students (30.5% male; mean age: 22.69) from more than 40 universities across Germany participated. We found that there is room for improvement with regard to the consumption of specific food groups, for example, fruits and vegetables. The main barriers to healthy eating were lack of time due to studies, lack of healthy meals at the university canteen, and high prices of healthy foods. Cluster analysis revealed that barriers to healthy eating might affect only specific subgroups, for instance freshmen. Changes in eating behaviour since matriculation were found in the consumption of meat, fish, and regular meals. Future qualitative studies may help to explore why university students change their eating behaviour since the time of matriculation. Such knowledge is necessary to inform health promotion strategies in the university setting. Copyright © 2016 Elsevier Ltd. All rights reserved.

Self-Esteem, Locus of Control, and First-Time NCLEX-RN Passage of BSN Students at Historically Black Colleges and Universities.

Science.gov (United States)

Chavis, Pamella Ivey

Relationships between self-esteem, locus of control (LOC), and first-time passage of National Council Licensure Examination for Registered Nurses (NCLEX-RN®) were examined at baccalaureate nursing programs at two historically black colleges and universities. Shortages continue to exceed demands for RNs prepared at the baccalaureate level. Inconsistent pass rates on the NCLEX-RN for graduates of historically black colleges and universities impede the supply of RNs. Surveys and archival data were used to examine characteristics of the sample and explore relationships among variables. All participants (N = 90) reported high self-esteem and internal LOC. Models suggested that all those with high self-esteem and internal LOC would pass the NCLEX-RN; only 85 percent passed the first time. Statistical analysis revealed a lack of statistical significance between self-esteem, LOC, and first-time passage. Variables not included in the study may have affected first-time passage.

How Need-Based Financial Aid Reduces College Attrition among Low-Income Public University Students: The Role of Time Use

Science.gov (United States)

Goldrick-Rab, Sara; Harris, Douglas N.; Benson, James

2011-01-01

The authors examine whether a need-based financial grant distribution "at random" to 1,500 Wisconsin Pell Grant recipients attending 13 public universities had an impact on how they allocated their time devoted to (a) working, (b) studying, (c) sleeping, and (d) socializing. To test whether time use mediates the relationship between aid…

Time diary and questionnaire assessment of factors associated with academic and personal success among university undergraduates.

Science.gov (United States)

George, Darren; Dixon, Sinikka; Stansal, Emory; Gelb, Shannon Lund; Pheri, Tabitha

2008-01-01

A sample of 231 students attending a private liberal arts university in central Alberta, Canada, completed a 5-day time diary and a 71-item questionnaire assessing the influence of personal, cognitive, and attitudinal factors on success. The authors used 3 success measures: cumulative grade point average (GPA), Personal Success--each participant's rating of congruence between stated goals and progress toward those goals--and Total Success--a measure that weighted GPA and Personal Success equally. The greatest predictors of GPA were time-management skills, intelligence, time spent studying, computer ownership, less time spent in passive leisure, and a healthy diet. Predictors of Personal Success scores were clearly defined goals, overall health, personal spirituality, and time-management skills. Predictors of Total Success scores were clearly defined goals, time-management skills, less time spent in passive leisure, healthy diet, waking up early, computer ownership, and less time spent sleeping. Results suggest alternatives to traditional predictors of academic success.

Universe symmetries

International Nuclear Information System (INIS)

Souriau, J.M.

1984-01-01

The sky uniformity can be noticed in studying the repartition of objects far enough. The sky isotropy description uses space rotations. The group theory elements will allow to give a meaning at the same time precise and general to the word a ''symmetry''. Universe models are reviewed, which must have both of the following qualities: - conformity with the physic known laws; - rigorous symmetry following one of the permitted groups. Each of the models foresees that universe evolution obeys an evolution equation. Expansion and big-bang theory are recalled. Is universe an open or closed space. Universe is also electrically neutral. That leads to a work hypothesis: the existing matter is not given data of universe but it appeared by evolution from nothing. Problem of matter and antimatter is then raised up together with its place in universe [fr

A Brief Study of Variation Theory in Quality Management

Directory of Open Access Journals (Sweden)

Mostafa Farah Bakhsh

2016-06-01

Full Text Available Variation is part of everyday life and exists all the time. Variation is the product of differences. Difference in nature of processes results in different products during the time. Proper diagnosis of variation patterns in minimizing the loss is necessary. Continuous quality improvement is regarded as successive reduction of performance variation for delivering high quality products to the customers. In Deming viewpoint, quality deviation is classified to two groups of common and special causes. Variation is not a new word, but understanding and concerns about it are modern. First step in performance variation management is acceptance and belief of variation. For proper management of variations, appropriate tools should be used for detection and display of them. Control are useful tools in recognition, analysis and removing process performance variations.

Targeted, Timely, Learning Support for International Students: One Australian University's Approach

Science.gov (United States)

Baird, Craig

2012-01-01

This paper documents the approach taken by an Australian University to enhance student study skills, development of academic language, and writing skills. The Curtin Business School (CBS) has the only fully faculty-based student learning support centre at Curtin University in Western Australia. Called the CBS Communication Skills Centre (CSC) it…

The real-time neutron radiography system at Texas A and M University

International Nuclear Information System (INIS)

Reuscher, Jon A.

1990-01-01

This paper reports on the development and fabrication of a real-time system at Texas A and M University using commercially available and relatively inexpensive components. The real-time neutron radiography system consists of two major components: a camera and image processing equipment. The neutron beam provides a thermal neutron flux of 10 neutrons/cm -sec (cadmium ratio of 4.0) with the TRIGA reactor operating at a power of 1 MW. A remotely operated turntable is used to position the sample in the neutron beam for optimum viewing and ease of changing position. The front surface mirror at 45 deg. to the neutron beam reflects the scintillation image to the lens. The IRO and CCD camera are placed behind shielding out of the neutron. Results using the imaging system for a cadmium plate (0.032 inch thick) with several holes of different diameters are presented. Applications of this neutron radiography system include sensitivity indicators for the spatial resolution of bubbles in water-filled tubes, moisture content of zeolite samples, operating heat pipes and the freezing and thawing of metallic samples

Universal Linear Scaling of Permeability and Time for Heterogeneous Fracture Dissolution

Science.gov (United States)

Wang, L.; Cardenas, M. B.

2017-12-01

Fractures are dynamically changing over geological time scale due to mechanical deformation and chemical reactions. However, the latter mechanism remains poorly understood with respect to the expanding fracture, which leads to a positively coupled flow and reactive transport processes, i.e., as a fracture expands, so does its permeability (k) and thus flow and reactive transport processes. To unravel this coupling, we consider a self-enhancing process that leads to fracture expansion caused by acidic fluid, i.e., CO2-saturated brine dissolving calcite fracture. We rigorously derive a theory, for the first time, showing that fracture permeability increases linearly with time [Wang and Cardenas, 2017]. To validate this theory, we resort to the direct simulation that solves the Navier-Stokes and Advection-Diffusion equations with a moving mesh according to the dynamic dissolution process in two-dimensional (2D) fractures. We find that k slowly increases first until the dissolution front breakthrough the outbound when we observe a rapid k increase, i.e., the linear time-dependence of k occurs. The theory agrees well with numerical observations across a broad range of Peclet and Damkohler numbers through homogeneous and heterogeneous 2D fractures. Moreover, the theory of linear scaling relationship between k and time matches well with experimental observations of three-dimensional (3D) fractures' dissolution. To further attest to our theory's universality for 3D heterogeneous fractures across a broad range of roughness and correlation length of aperture field, we develop a depth-averaged model that simulates the process-based reactive transport. The simulation results show that, regardless of a wide variety of dissolution patterns such as the presence of dissolution fingers and preferential dissolution paths, the linear scaling relationship between k and time holds. Our theory sheds light on predicting permeability evolution in many geological settings when the self

Finite time exergy analysis and multi-objective ecological optimization of a regenerative Brayton cycle considering the impact of flow rate variations

International Nuclear Information System (INIS)

Naserian, Mohammad Mahdi; Farahat, Said; Sarhaddi, Faramarz

2015-01-01

Highlights: • Defining a dimensionless parameter includes the finite-time and size concepts. • Inserting the concept of exergy of fluid streams into finite-time thermodynamics. • Defining, drawing and modifying of maximum ecological function curve. • Suggesting the appropriate performance zone, according to maximum ecological curve. - Abstract: In this study, the optimal performance of a regenerative Brayton cycle is sought through power and then ecological function maximization using finite-time thermodynamic concept and finite-size components. Multi-objective optimization is used for maximizing the ecological function. Optimizations are performed using genetic algorithm. In order to take into account the finite-time and finite-size concepts in current problem, a dimensionless mass-flow parameter is introduced deploying time variations. The variations of output power, total exergy destruction of the system, and decision variables for the optimum state (maximum ecological function state) are compared to the maximum power state using the dimensionless parameter. The modified ecological function in optimum state is obtained and plotted relating to the dimensionless mass-flow parameter. One can see that the modified ecological function study results in a better performance than that obtained with the maximum power state. Finally, the appropriate performance zone of the heat engine will be obtained

University Leadership during Times of Significant Transformation: A Case of Kyambogo University in Uganda

Science.gov (United States)

Namubiru, Gertrude; Onen, David; Oonyu, Joseph

2017-01-01

This study investigated how leadership was exercised at Kyambogo University [KyU] (in Uganda) during its formation that involved the merger of three tertiary institutions and the period immediately thereafter. This was regarded as a period of significant transformation at the institution. The study was prompted by the rampant strikes and protests…

Developmental Change and Time-Specific Variation in Global and Specific Aspects of Self-Concept in Adolescence and Association with Depressive Symptoms

Science.gov (United States)

Kuzucu, Yasar; Bontempo, Daniel E.; Hofer, Scott M.; Stallings, Michael C.; Piccinin, Andrea M.

2014-01-01

Previous research has demonstrated that adolescents make differential self-evaluations in multiple domains that include physical appearance, academic competence, and peer acceptance. We report growth curve analyses over a seven year period from age 9 to age 16 on the six domains of the Harter Self-Perception Profile for Children. In general, we find little change in self-concept, on average, but do find substantial individual differences in level, rate of change, and time-specific variation in these self- evaluations. The results suggest that sex differences and adoptive status were related to only certain aspects of the participants’ self-concept. Depressive symptoms were found to have significant effects on individual differences in rate of change and on time-specific variation in general self-concept, as well as on some of the specific domains of self-concept. PMID:25143664

A rare variation of the digastric muscle

Science.gov (United States)

KALNIEV, MANOL; KRASTEV, DIMO; KRASTEV, NIKOLAY; VIDINOV, KALIN; VELTCHEV, LUDMIL; APOSTOLOV, ALEXANDER; MILEVA, MILKA

2013-01-01

The digastric muscle is composed by two muscle bellies: an anterior and a posterior, joined by an intermediate tendon. This muscle is situated in the anterior region of the neck. The region between the hyoid bone and the mandible is divided by an anterior belly into two triangles: the submandibular situated laterally and the submental triangle which is located medially. We found that the anatomical variations described in the literature relate mainly to the anterior belly and consist of differences in shape and attachment of the muscle. During routine dissection in February 2013 in the section hall of the Department of Anatomy and Histology in Medical University – Sofia we came across a very interesting variation of the digastric muscle. The digastric muscles that presented anatomical variations were photographed using a Sony Cyber-shot DSC-T1 camera, with a Carl Zeiss Vario-Tessar lens. We found out bilateral variation of the digastric muscle in one cadaver. The anterior bellies were very thin and insert to the hyoid bone. Two anterior bellies connect each other and thus they formed a loop. The anatomical variations observed of our study related only to the anterior belly, as previously described by other authors. It is very important to consider the occurrence of the above mentioned variations in the digastric muscle when surgical procedures are performed on the anterior region of the neck. PMID:26527971

Structure of carbon monoxide time variations in the atmospheric thickness over Central Eurasia (Issyk Kul Monitoring Station)

Science.gov (United States)

Aref'ev, V. N.; Kashin, F. V.; Orozaliev, M. D.; Sizov, N. I.; Sinyakov, V. P.; Sorokina, L. I.

2013-03-01

The results of measurements of the CO content in the atmospheric thickness by the method of solar molecular-absorption spectroscopy are presented. Over 87 months of observations, the annual mean CO content decreased by ˜19% at a mean rate of changes equal to -(0.14 ± 0.02) atm cm per year. Maxima and minima of seasonal variations most often fall on February and September, respectively. The mean overall amplitude of changes in the CO content during the annual cycle is about 50% of the mean value. The Fourier analysis revealed variations in the CO composition with periods from 3 to 84 months. A simple statistical model satisfactorily describes time changes in the CO content in the atmospheric thickness. The results of measurements of the CO content in the atmospheric thickness are compared with the data of CO measurements in samples of surface air at stations of the Global Atmospheric Watch.

Explaining health care expenditure variation: large-sample evidence using linked survey and health administrative data.

Science.gov (United States)

Ellis, Randall P; Fiebig, Denzil G; Johar, Meliyanni; Jones, Glenn; Savage, Elizabeth

2013-09-01

Explaining individual, regional, and provider variation in health care spending is of enormous value to policymakers but is often hampered by the lack of individual level detail in universal public health systems because budgeted spending is often not attributable to specific individuals. Even rarer is self-reported survey information that helps explain this variation in large samples. In this paper, we link a cross-sectional survey of 267 188 Australians age 45 and over to a panel dataset of annual healthcare costs calculated from several years of hospital, medical and pharmaceutical records. We use this data to distinguish between cost variations due to health shocks and those that are intrinsic (fixed) to an individual over three years. We find that high fixed expenditures are positively associated with age, especially older males, poor health, obesity, smoking, cancer, stroke and heart conditions. Being foreign born, speaking a foreign language at home and low income are more strongly associated with higher time-varying expenditures, suggesting greater exposure to adverse health shocks. Copyright © 2013 John Wiley & Sons, Ltd.

Chaotic universe model.

Science.gov (United States)

Aydiner, Ekrem

2018-01-15

In this study, we consider nonlinear interactions between components such as dark energy, dark matter, matter and radiation in the framework of the Friedman-Robertson-Walker space-time and propose a simple interaction model based on the time evolution of the densities of these components. By using this model we show that these interactions can be given by Lotka-Volterra type equations. We numerically solve these coupling equations and show that interaction dynamics between dark energy-dark matter-matter or dark energy-dark matter-matter-radiation has a strange attractor for 0 > w de  >-1, w dm  ≥ 0, w m  ≥ 0 and w r  ≥ 0 values. These strange attractors with the positive Lyapunov exponent clearly show that chaotic dynamics appears in the time evolution of the densities. These results provide that the time evolution of the universe is chaotic. The present model may have potential to solve some of the cosmological problems such as the singularity, cosmic coincidence, big crunch, big rip, horizon, oscillation, the emergence of the galaxies, matter distribution and large-scale organization of the universe. The model also connects between dynamics of the competing species in biological systems and dynamics of the time evolution of the universe and offers a new perspective and a new different scenario for the universe evolution.

A lightweight universe?

Science.gov (United States)

Bahcall, Neta A.; Fan, Xiaohui

1998-01-01

How much matter is there in the universe? Does the universe have the critical density needed to stop its expansion, or is the universe underweight and destined to expand forever? We show that several independent measures, especially those utilizing the largest bound systems known—clusters of galaxies—all indicate that the mass-density of the universe is insufficient to halt the expansion. A promising new method, the evolution of the number density of clusters with time, provides the most powerful indication so far that the universe has a subcritical density. We show that different techniques reveal a consistent picture of a lightweight universe with only ∼20–30% of the critical density. Thus, the universe may expand forever. PMID:9600898

Modelling regional variation of first-time births in Denmark 1980-1994 by an age-period-cohort model

Directory of Open Access Journals (Sweden)

Lisbeth B. Knudsen

2005-12-01

Full Text Available Despite the small size of Denmark, there have traditionally been rather consistent regional differences in fertility rates. We apply the statistical age-period-cohort model to include the effect of these three time-related factors thereby concisely illuminating the regional differences of first-time births in Denmark. From the Fertility of Women and Couples Dataset we obtain data on number of births by nulliparous women by year (1980-1994, age (15-45 and county of residence. We show that the APC-model describes the fertility rates of nulliparous women satisfactorily. To catch the regional variation an interaction parameter between age and county is necessary, which provides a surprisingly good description suggesting that the county-specific age-distributions of first-time fertility rates differ. Our results are in general agreement with the 'moral geography' concepts of Tonboe (2001.

Modelling regional variation of first-time births in Denmark 1980-1994 by an age-period-cohort model

DEFF Research Database (Denmark)

Thygesen, Lau Caspar; Knudsen, Lisbeth B.; Keiding, Niels

2005-01-01

Despite the small size of Denmark, there have traditionally been rather consistent regional differences in fertility rates. We apply the statistical age-period-cohort model to include the effect of these three time-related factors thereby concisely illuminating the regional differences of first......-time births in Denmark. From the Fertility of Women and Couples Dataset we obtain data on number of births by nulliparous women by year (1980-1994), age (15-45) and county of residence. We show that the APC-model describes the fertility rates of nulliparous women satisfactorily. To catch the regional...... variation an interaction parameter between age and county is necessary, which provides a surprisingly good description suggesting that the county-specific age-distributions of first-time fertility rates differ. Our results are in general agreement with the 'moral geography' concepts of Tonboe (2001)....

Characteristics of seasonal variation and solar activity dependence of the geomagnetic solar quiet daily variation

Science.gov (United States)

Shinbori, A.; Koyama, Y.; Nose, M.; Hori, T.

2017-12-01

Characteristics of seasonal variation and solar activity dependence of the X- and Y-components of the geomagnetic solar quiet (Sq) daily variation at Memanbetsu in mid-latitudes and Guam near the equator have been investigated using long-term geomagnetic field data with 1-h time resolution from 1957 to 2016. In this analysis, we defined the quiet day when the maximum value of the Kp index is less than 3 for that day. In this analysis, we used the monthly average of the adjusted daily F10.7 corresponding to geomagnetically quiet days. For identification of the monthly mean Sq variation in the X and Y components (Sq-X and Sq-Y), we first determined the baseline of the X and Y components from the average value from 22 to 2 h (LT: local time) for each quiet day. Next, we calculated a deviation from the baseline of the X- and Y-components of the geomagnetic field for each quiet day, and computed the monthly mean value of the deviation for each local time. As a result, Sq-X and Sq-Y shows a clear seasonal variation and solar activity dependence. The amplitude of seasonal variation increases significantly during high solar activities, and is proportional to the solar F10.7 index. The pattern of the seasonal variation is quite different between Sq-X and Sq-Y. The result of the correlation analysis between the solar F10.7 index and Sq-X and Sq-Y shows almost the linear relationship, but the slope and intercept of the linear fitted line varies as function of local time and month. This implies that the sensitivity of Sq-X and Sq-Y to the solar activity is different for different local times and seasons. The local time dependence of the offset value of Sq-Y at Guam and its seasonal variation suggest a magnetic field produced by inter-hemispheric field-aligned currents (FACs). From the sign of the offset value of Sq-Y, it is infer that the inter-hemispheric FACs flow from the summer to winter hemispheres in the dawn and dusk sectors and from the winter to summer hemispheres in

Variational approach to nuclear fluid dynamics

International Nuclear Information System (INIS)

Da Providencia, J.P.; Holzwarth, G.

1983-01-01

A variational derivation of a fluid-dynamical formalism for finite Fermi systems is presented which is based on a single determinant as variational function and does not exclude the possibility of transverse flow. Therefore the explicit specification of the time-odd part has to go beyond the local chi-approximation, while the time-even part is taken in the generalized scaling form. The necessary boundary conditions are derived from the variation of the lagrangian. The results confirm previous simplified approaches to a remarkable degree for quadrupole modes; for other multipolarities the deviations are much less than might be expected according to a sizeable change in the transverse sound speed. (orig.)

Variational coupling between q-number and c-number dynamics

International Nuclear Information System (INIS)

Amaral, C.M. do; Joffily, S.

1984-01-01

The time-dependent quantum variational principle is generalized for the case of hamiltonian operators having real parameters and their time derivates. The obtained variational system is formed by a Schroedinger equation coupled to a Lagrange equation system, where the lagrangian is the average value of the parametrized hamiltonian operator. The consequent dynamics of the variational principle, describes the interaction between a q-number sub-dynamics with a c-number sub-dynamics. In the ((h/2π)) 0 -order W.K.B. approximation, the variational system reduces to a Hamilton-Jacobi-like equation, coupled to a Lagrange equation family. The formal features of the obtained variational system are appropriated for the description of, adiabatics and non-adiabatics, time-dependent q-number c-number interactions. (L.C.) [pt

Time-Dependent Effects of Acute Exercise on University Students’ Cognitive Performance in Temperate and Cold Environments

Directory of Open Access Journals (Sweden)

Ling-Yu Ji

2017-07-01

Full Text Available Background: Few studies have examined the acute exercise-induced changes in cognitive performance in different thermal environments and the time course effects.Objective: Investigate the time-dependent effects of acute exercise on university students’ processing speed, working memory and cognitive flexibility in temperate and cold environments.Method: Twenty male university students (age 23.5 ± 2.0 years with moderate physical activity level participated in a repeated-measures within-subjects design. Processing speed, working memory and cognitive flexibility were assessed using CogState test battery at baseline (BASE, followed by a 45-min rest (REST, immediately after (EX and 30 min after (POST-EX 30-min moderate-intensity treadmill running in both temperate (TEMP; 25°C and cold (COLD; 10°C environments. Mean skin temperature (MST and thermal sensation (TS were also recorded. Two-way repeated measures ANOVA was performed to analyze each variable. Spearman’s rho was used to identify the correlations between MST, TS and cognitive performance.Results: Reaction time (RT of processing speed and working memory decreased immediately after exercise in both conditions (processing speed: p = 0.003; working memory: p = 0.007. The facilitating effects on processing speed disappeared within 30 min after exercise in TEMP (p = 0.163 and COLD (p = 0.667, while improvements on working memory remained 30 min after exercise in TEMP (p = 0.047, but not in COLD (p = 0.663. Though RT of cognitive flexibility reduced in both conditions (p = 0.003, no significance was found between EX and REST (p = 0.135. Increased MST and TS were significantly associated with reductions in processing speed RT (MST: r = -0.341, p < 0.001; TS: r = -0.262, p = 0.001 and working memory RT (MST: r = -0.282, p < 0.001; TS: r = -0.2229, p = 0.005, and improvements in working memory accuracy (MST: r = 0.249, p = 0.002; TS: r = 0.255, p = 0.001.Conclusion: The results demonstrate

VARIATIONAL PRINCIPLE FOR PLANETARY INTERIORS

International Nuclear Information System (INIS)

Zeng, Li; Jacobsen, Stein B.

2016-01-01

In the past few years, the number of confirmed planets has grown above 2000. It is clear that they represent a diversity of structures not seen in our own solar system. In addition to very detailed interior modeling, it is valuable to have a simple analytical framework for describing planetary structures. The variational principle is a fundamental principle in physics, entailing that a physical system follows the trajectory, which minimizes its action. It is alternative to the differential equation formulation of a physical system. Applying the variational principle to the planetary interior can beautifully summarize the set of differential equations into one, which provides us some insight into the problem. From this principle, a universal mass–radius relation, an estimate of the error propagation from the equation of state to the mass–radius relation, and a form of the virial theorem applicable to planetary interiors are derived.

Revisiting the returns-volume relationship: Time variation, alternative measures and the financial crisis

Science.gov (United States)

Cook, Steve; Watson, Duncan

2017-03-01

Following its introduction in the seminal study of Osborne (1959), a voluminous literature has emerged examining the returns-volume relationship for financial assets. The present paper revisits this relationship in an examination of the FTSE100 which extends the existing literature in two ways. First, alternative daily measures of the FTSE100 index are used to create differing returns and absolute returns series to employ in an examination of returns-volume causality. Second, rolling regression analysis is utilised to explore potential time variation in the returns-volume relationship. The findings obtained depict a hitherto unconsidered complexity in this relationship with the type of returns series considered and financial crisis found to be significant underlying factors. The implications of the newly derived results for both the understanding of the nature of the returns-volume relationship and the development of theories in connection to it are discussed.

Light Curve Variations of AR Lacertae

Directory of Open Access Journals (Sweden)

Il-Seong Nha

1991-12-01

Full Text Available Sixteen unitary Light curves of AR Lac in B and V are made at Yonsei University Observatory in the period of 1980-1988. Some overview findings of light variations are made. (1 The light variations outside eclipse follow none of the wave migration patterns reported by previous investigators. (2 Complicated shapes outside eclipse are apparently much reduced in the light curves of 1983-1984. This suggests that, in the future, AR Lac has a chance to attain a normal state with mo complicated interactions. (3 The depths of the primary and the secondary mid-eclipses are changing year-to-year. (4 The K0 star, the larger component, has brightened by 0.m14 V, while the G2 star has shown a fluctuation of about 0.m05 in V. (5 The B-V values at primary mid-eclipse have no correlation with the depth variations. (6 Independently of the increase of maximum brightness, the B-V colors in the non-eclipsed phases changed slightly over the years.

Universal algorithm of time sharing

International Nuclear Information System (INIS)

Silin, I.N.; Fedyun'kin, E.D.

1979-01-01

Timesharing system algorithm is proposed for the wide class of one- and multiprocessor computer configurations. Dynamical priority is the piece constant function of the channel characteristic and system time quantum. The interactive job quantum has variable length. Characteristic recurrent formula is received. The concept of the background job is introduced. Background job loads processor if high priority jobs are inactive. Background quality function is given on the base of the statistical data received in the timesharing process. Algorithm includes optimal trashing off procedure for the jobs replacements in the memory. Sharing of the system time in proportion to the external priorities is guaranteed for the all active enough computing channels (back-ground too). The fast answer is guaranteed for the interactive jobs, which use small time and memory. The external priority control is saved for the high level scheduler. The experience of the algorithm realization on the BESM-6 computer in JINR is discussed

Universal behaviour of interoccurrence times between losses in financial markets: An analytical description

Science.gov (United States)

Ludescher, J.; Tsallis, C.; Bunde, A.

2011-09-01

We consider 16 representative financial records (stocks, indices, commodities, and exchange rates) and study the distribution PQ(r) of the interoccurrence times r between daily losses below negative thresholds -Q, for fixed mean interoccurrence time RQ. We find that in all cases, PQ(r) follows the form PQ(r)~1/[(1+(q- 1)βr]1/(q-1), where β and q are universal constants that depend only on RQ, but not on a specific asset. While β depends only slightly on RQ, the q-value increases logarithmically with RQ, q=1+q0 ln(RQ/2), such that for RQ→2, PQ(r) approaches a simple exponential, PQ(r)cong2-r. The fact that PQ does not scale with RQ is due to the multifractality of the financial markets. The analytic form of PQ allows also to estimate both the risk function and the Value-at-Risk, and thus to improve the estimation of the financial risk.

Differentially expressed genes linked to natural variation in long-term memory formation in Cotesia parasitic wasps

NARCIS (Netherlands)

Vugt, van J.J.F.A.; Hoedjes, K.M.; Geest, van de H.C.; Schijlen, E.G.W.M.; Vet, L.E.M.; Smid, H.M.

2015-01-01

Even though learning and memory are universal traits in the Animal Kingdom, closely related species reveal substantial variation in learning rate and memory dynamics. To determine the genetic background of this natural variation, we studied two congeneric parasitic wasp species, Cotesia glomerata

Differentially expressed genes linked to natural variation in long-term memory formation in Cotesia parasitic wasps

NARCIS (Netherlands)

Van Vugt, Joke J. F. A.; Hoedjes, Katja M.; Van de Geest, Henri C.; Schijlen, Elio W. G. M.; Vet, Louise E. M.; Smid, Hans M.

2015-01-01

BACKGROUND: Even though learning and memory are universal traits in the Animal Kingdom, closely related species reveal substantial variation in learning rate and memory dynamics. To determine the genetic background of this natural variation, we studied two congeneric parasitic wasp species, Cotesia

Global variations and time trends in the prevalence of childhood myopia, a systematic review and quantitative meta-analysis: implications for aetiology and early prevention.

Science.gov (United States)

Rudnicka, Alicja R; Kapetanakis, Venediktos V; Wathern, Andrea K; Logan, Nicola S; Gilmartin, Bernard; Whincup, Peter H; Cook, Derek G; Owen, Christopher G

2016-07-01

The aim of this review was to quantify the global variation in childhood myopia prevalence over time taking account of demographic and study design factors. A systematic review identified population-based surveys with estimates of childhood myopia prevalence published by February 2015. Multilevel binomial logistic regression of log odds of myopia was used to examine the association with age, gender, urban versus rural setting and survey year, among populations of different ethnic origins, adjusting for study design factors. 143 published articles (42 countries, 374 349 subjects aged 1-18 years, 74 847 myopia cases) were included. Increase in myopia prevalence with age varied by ethnicity. East Asians showed the highest prevalence, reaching 69% (95% credible intervals (CrI) 61% to 77%) at 15 years of age (86% among Singaporean-Chinese). Blacks in Africa had the lowest prevalence; 5.5% at 15 years (95% CrI 3% to 9%). Time trends in myopia prevalence over the last decade were small in whites, increased by 23% in East Asians, with a weaker increase among South Asians. Children from urban environments have 2.6 times the odds of myopia compared with those from rural environments. In whites and East Asians sex differences emerge at about 9 years of age; by late adolescence girls are twice as likely as boys to be myopic. Marked ethnic differences in age-specific prevalence of myopia exist. Rapid increases in myopia prevalence over time, particularly in East Asians, combined with a universally higher risk of myopia in urban settings, suggest that environmental factors play an important role in myopia development, which may offer scope for prevention. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Variations in Student Mental Health and Treatment Utilization Across US Colleges and Universities.

Science.gov (United States)

Ketchen Lipson, Sarah; Gaddis, S Michael; Heinze, Justin; Beck, Kathryn; Eisenberg, Daniel

2015-01-01

On US college campuses, mental health problems are highly prevalent, appear to be increasing, and are often untreated. Concerns about student mental health are well documented, but little is known about potential variations across the diversity of institutions of higher education. Participants were 43,210 undergraduates at 72 campuses that participated in the Healthy Minds Study from 2007 to 2013. Multivariable logistic regressions focus on associations between institutional characteristics and student mental health and treatment utilization. The following institutional characteristics are associated with worse mental health: doctoral-granting, public, large enrollment, nonresidential, less competitive, and lower graduation rates. Among students with apparent mental health problems, treatment utilization is higher at doctorate-granting institutions, baccalaureate colleges, institutions with small enrollments, and schools with strong residential systems. Although high rates of mental health problems and low treatment utilization are major concerns at all types of institutions of higher education, substantial variation occurs across campuses.

The inflationary universe

International Nuclear Information System (INIS)

Guth, A.; Steinhardt, P.

1993-01-01

According to the inflationary model, the universe had a brief period of extraordinary rapid expansion, or inflation, during which its diameter increased by a factor at least 10 25 times larger (and perhaps much larger still) than had been previously thought. All the matter and energy in the universe could have been created from virtually nothing. Features of this article are: comparison of standard and inflationary modes, the horizon problem, the geometry of the universe, spontaneous symmetry breaking and the Higgs mechanism (energy density of the Higgs fields), the flatness problem, the new inflationary universe (new Higgs fields and false vacuum), conserved quantities in the universe. 12 figs., 11 refs

Variations in Student Mental Health and Treatment Utilization across US Colleges and Universities

Science.gov (United States)

Ketchen Lipson, Sarah; Gaddis, S. Michael; Heinze, Justin; Beck, Kathryn; Eisenberg, Daniel

2015-01-01

Objective: On US college campuses, mental health problems are highly prevalent, appear to be increasing, and are often untreated. Concerns about student mental health are well documented, but little is known about potential variations across the diversity of institutions of higher education. Participants: Participants were 43,210 undergraduates at…

Variations in VLT/UVES-based OH rotational temperatures for time scales from hours to 15 years

Science.gov (United States)

Noll, Stefan; Kimeswenger, Stefan; Proxauf, Bastian; Kausch, Wolfgang; Unterguggenberger, Stefanie; Jones, Amy M.

2017-04-01

Hydroxyl (OH) emission is an important tracer of the climate, chemistry, and dynamics of the Earth's mesopause region. However, the relation of intensity variations in different OH lines is not well understood yet. This is critical for the most popular use of OH lines: the estimate of ambient temperatures based on transitions at low rotational levels of the same band. It is possible that the measured variability of the derived rotational temperature does not coincide with changes in the ambient temperature. Such differences can be caused by varying deviations from the local thermodynamic equilibrium (LTE) for the population distribution over the considered rotational levels. The non-LTE effects depend on the ratio of the thermalising collisions (mostly related to molecular oxygen) and competing radiative transitions or collisions without thermalisation of the rotational level distribution. Therefore, significant changes in the vertical structure of excited OH and its main quenchers can affect the temperature measurements. We have investigated the variability of OH rotational temperatures and the corresponding contributions of non-LTE effects for different OH bands and time scales up to 15 years based on data of the high-resolution echelle spectrograph UVES at the Very Large Telescope at Cerro Paranal in Chile. In order to link the measured rotational temperatures with the structure of the OH emission layer, we have also studied OH emission and kinetic temperature profiles from the multi-channel radiometer SABER on the TIMED satellite taken between 2002 and 2015. The results show that non-LTE contributions can significantly affect the OH rotational temperatures. Their variations can be especially strong during the night and for high upper vibrational levels of the transitions, where amplitudes of several Kelvins can be measured. They appear to be weak if long-term variations such as those caused by the solar cycle are investigated. These differences in the response

Mathematics at University

DEFF Research Database (Denmark)

Winsløw, Carl

2015-01-01

Mathematics is studied in universities by a large number of students. At the same time it is a field of research for a (smaller) number of university teachers. What relations, if any, exist between university research and teaching of mathematics? Can research “support” teaching? What research...... and what teaching? In this presentation we propose a theoretical framework to study these questions more precisely, based on the anthropological theory of didactics. As a main application, the links between the practices of mathematical research and university mathematics teaching are examined...

Time-Depending Parametric Variational Approach for an Economic General Equilibrium Problem of Pure Exchange with Application

International Nuclear Information System (INIS)

Scaramuzzino, F.

2009-01-01

This paper considers a qualitative analysis of the solution of a pure exchange general economic equilibrium problem according to two independent parameters. Some recently results obtained by the author in the static and the dynamic case have been collected. Such results have been applied in a particular parametric case: it has been focused the attention on a numerical application for which the existence of the solution of time-depending parametric variational inequality that describes the equilibrium conditions has been proved by means of the direct method. By using MatLab computation after a linear interpolation, the curves of equilibrium have been visualized.

Real-time electrical impedimetric monitoring of blood coagulation process under temperature and hematocrit variations conducted in a microfluidic chip.

Directory of Open Access Journals (Sweden)

Kin Fong Lei

Full Text Available Blood coagulation is an extremely complicated and dynamic physiological process. Monitoring of blood coagulation is essential to predict the risk of hemorrhage and thrombosis during cardiac surgical procedures. In this study, a high throughput microfluidic chip has been developed for the investigation of the blood coagulation process under temperature and hematocrit variations. Electrical impedance of the whole blood was continuously recorded by on-chip electrodes in contact with the blood sample during coagulation. Analysis of the impedance change of the blood was conducted to investigate the characteristics of blood coagulation process and the starting time of blood coagulation was defined. The study of blood coagulation time under temperature and hematocrit variations was shown a good agreement with results in the previous clinical reports. The electrical impedance measurement for the definition of blood coagulation process provides a fast and easy measurement technique. The microfluidic chip was shown to be a sensitive and promising device for monitoring blood coagulation process even in a variety of conditions. It is found valuable for the development of point-of-care coagulation testing devices that utilizes whole blood sample in microliter quantity.

Amplitude Variations in Pulsating Red Giants. II. Some Systematics

Science.gov (United States)

Percy, J. R.; Laing, J.

2017-12-01

In order to extend our previous studies of the unexplained phenomenon of cyclic amplitude variations in pulsating red giants, we have used the AAVSO time-series analysis package vstar to analyze long-term AAVSO visual observations of 50 such stars, mostly Mira stars. The relative amount of the variation, typically a factor of 1.5, and the time scale of the variation, typically 20-35 pulsation periods, are not significantly different in longer-period, shorter-period, and carbon stars in our sample, and they also occur in stars whose period is changing secularly, perhaps due to a thermal pulse. The time scale of the variations is similar to that in smaller-amplitude SR variables, but the relative amount of the variation appears to be larger in smaller-amplitude stars, and is therefore more conspicuous. The cause of the amplitude variations remains unclear, though they may be due to rotational modulation of a star whose pulsating surface is dominated by the effects of large convective cells.

Implications of Galaxy Buildup for Putative IMF Variations in Massive Galaxies

Science.gov (United States)

Blancato, Kirsten; Genel, Shy; Bryan, Greg

2017-08-01

Recent observational evidence for initial mass function (IMF) variations in massive quiescent galaxies at z = 0 challenges the long-established paradigm of a universal IMF. While a few theoretical models relate the IMF to birth cloud conditions, the physical driver underlying these putative IMF variations is still largely unclear. Here we use post-processing analysis of the Illustris cosmological hydrodynamical simulation to investigate possible physical origins of IMF variability with galactic properties. We do so by tagging stellar particles in the simulation (each representing a stellar population of ≈ {10}6 {M}⊙ ) with individual IMFs that depend on various physical conditions, such as velocity dispersion, metallicity, or star formation rate, at the time and place in which the stars are formed. We then follow the assembly of these populations throughout cosmic time and reconstruct the overall IMF of each z = 0 galaxy from the many distinct IMFs it is composed of. Our main result is that applying the observed relations between IMF and galactic properties to the conditions at the star formation sites does not result in strong enough IMF variations between z = 0 galaxies. Steeper physical IMF relations are required for reproducing the observed IMF trends, and some stellar populations must form with more extreme IMFs than those observed. The origin of this result is the hierarchical nature of massive galaxy assembly, and it has implications for the reliability of the strong observed trends, for the ability of cosmological simulations to capture certain physical conditions in galaxies, and for theories of star formation aiming to explain the physical origin of a variable IMF.

Cone-Beam Computed Tomography–Guided Positioning of Laryngeal Cancer Patients with Large Interfraction Time Trends in Setup and Nonrigid Anatomy Variations

International Nuclear Information System (INIS)

Gangsaas, Anne; Astreinidou, Eleftheria; Quint, Sandra; Levendag, Peter C.; Heijmen, Ben

2013-01-01

Purpose: To investigate interfraction setup variations of the primary tumor, elective nodes, and vertebrae in laryngeal cancer patients and to validate protocols for cone beam computed tomography (CBCT)-guided correction. Methods and Materials: For 30 patients, CBCT-measured displacements in fractionated treatments were used to investigate population setup errors and to simulate residual setup errors for the no action level (NAL) offline protocol, the extended NAL (eNAL) protocol, and daily CBCT acquisition with online analysis and repositioning. Results: Without corrections, 12 of 26 patients treated with radical radiation therapy would have experienced a gradual change (time trend) in primary tumor setup ≥4 mm in the craniocaudal (CC) direction during the fractionated treatment (11/12 in caudal direction, maximum 11 mm). Due to these trends, correction of primary tumor displacements with NAL resulted in large residual CC errors (required margin 6.7 mm). With the weekly correction vector adjustments in eNAL, the trends could be largely compensated (CC margin 3.5 mm). Correlation between movements of the primary and nodal clinical target volumes (CTVs) in the CC direction was poor (r 2 =0.15). Therefore, even with online setup corrections of the primary CTV, the required CC margin for the nodal CTV was as large as 6.8 mm. Also for the vertebrae, large time trends were observed for some patients. Because of poor CC correlation (r 2 =0.19) between displacements of the primary CTV and the vertebrae, even with daily online repositioning of the vertebrae, the required CC margin around the primary CTV was 6.9 mm. Conclusions: Laryngeal cancer patients showed substantial interfraction setup variations, including large time trends, and poor CC correlation between primary tumor displacements and motion of the nodes and vertebrae (internal tumor motion). These trends and nonrigid anatomy variations have to be considered in the choice of setup verification protocol and

Time-temperature dependent variations in beta-carotene contents in carrot using different spectrophotometric techniques

Science.gov (United States)

Ullah, Rahat; Khan, Saranjam; Shah, Attaullah; Ali, Hina; Bilal, Muhammad

2018-05-01

The current study presents time dependent variations in the concentration of beta-carotene in carrot under different storage-temperature conditions using UV–VIS and Raman spectrophotometric techniques. The UV–VIS absorption spectra of beta-carotene extracted from carrot shows three distinct absorption peaks at 442, 467, and 500 nm with maximum absorption at 467 nm. These absorption peaks are very much reproducible and are assigned to β-carotene. Similarly, Raman spectra of carrot samples also confirmed the three main Raman peaks of beta-carotene at shift positions 1003, 1150, and 1515 cm‑1. An overall decrease in beta-carotene content has been observed for time-temperature conditions. These results depict a decrease of about 40% in the content of beta-carotene when carrot samples were stored in a refrigerator (4 °C) for the first 20 d, whereas a decrease of about 25% was observed when carrot samples were stored in a freezer (‑16 °C) for the same period. The objective of this study is to investigate the possible use of Raman spectroscopy and UV–VIS spectroscopy for quick and detailed analysis of changes (degradation) in beta-carotene content associated with time and temperature in storage (frozen foods) in order to promote quality foods for consumers. Future study with a greater focus on the concentration/content of beta-carotene in other fruits/vegetables is also desirable.

Incorporating Spatio-temporal Phenological Variation in Detecting Exotic Saltcedar Using Landsat Time Series

Science.gov (United States)

Diao, C.; Wang, L.

2017-12-01

The invasion of exotic species compromises ecosystem functions and causes substantial economic losses at the global scale. Over the past century, non-native saltcedar has expanded into most riparian zones in southwestern United States and posed significant threats to the native biotic communities. Repeated monitoring of saltcedar distribution is essential for conservation agencies to locate highly susceptible areas and develop corresponding control strategies. Throughout the phenological cycle, the leaf senescence stage has been found to be the most crucial in spectrally detecting saltcedar. However, due to climate variability and anthropogenic forcing, the timing of saltcedar leaf senescence may vary over space and time. This spatial and inter-annual variation need to be accommodated to pinpoint the appropriate remotely sensed imagery for saltcedar mapping. The objective of this study was to develop a Landsat-based Multiyear Spectral Angle Clustering (MSAC) model to monitor the inter-annual leaf senescence of exotic saltcedar. At the Landsat scale, the time series analysis of vegetation phenology is usually limited by the temporal resolution of images. The MSAC model can overcome this limit and take advantage of the Landsat images from multiple years to compensate the lack of images in a single year. Results indicated the MSAC model provided a Landsat-based solution to capture the inter-annual leaf senescence of saltcedar. Compared to traditional NDVI-based phenological approaches, the proposed model achieved a more accurate classification results of saltcedar across years. The MSAC model provides unique opportunities to guide the selection of appropriate remotely sensed image for repetitive saltcedar mapping.

[Part-time concepts in anaesthesia -example of a department of anaesthesiology at a university hospital in Germany].

Science.gov (United States)

Höltje, Maike; Osthaus, W Alexander; Koppert, Wolfgang

2015-05-01

Part-time work concepts are requested for different reasons from an increasing number of employees. Despite this fact there are no systematic part-time work concepts published in the German literature, especially for physicians working in hospitals. This article describes background and circumstances of a part-time work concept which was established two years ago in a department of anaesthesiology at a university hospital in Germany. This concept considers needs of young families as well as older employees. We are convinced that a transparent part-time work concept is a good argument for job-seeking physicians when deciding for an employer. The benefit for the already employed colleagues has at least the same value. © Georg Thieme Verlag Stuttgart · New York.

Local time, seasonal, and solar cycle dependency of longitudinal variations of TEC along the crest of EIA over India

Science.gov (United States)

Sunda, Surendra; Vyas, B. M.

2013-10-01

global wave number 4 structure in the Indian longitudinal region spanning from ~70 to 95°E forming the upward slope of the peak in the total electron content (TEC) are reported along the crest of equatorial ionization anomaly (EIA). The continuous and simultaneous measurements from five GPS stations of GPS Aided Geo Augmented Navigation (GAGAN) network are used in this study. The long-term database (2004-2012) is utilized for examining the local time, seasonal, and solar cycle dependency on the longitudinal variations of TEC. Our results confirm the existence of longitudinal variations of TEC in accordance with wave number 4 longitudinal structure including its strength. The results suggest that these variations, in general, start to develop at ~09 LT, achieve maximum strength at 12-15 LT, and decay thereafter, the decay rate depending on the season. They are more pronounced in equinoctial season followed by summer and winter. The longitudinal variations persist beyond midnight in equinox seasons, whereas in winter, they are conspicuously absent. Interestingly, they also exhibit significant solar cycle dependence in the solstices, whereas in the equinoxes, they are independent of solar activity. The comparison of crest-to-trough ratio (CTR) in the eastern (92°E) and western (72°E) extreme longitudes reveals higher CTR on the eastern side than over the western extreme, suggesting the role of nonmigrating tides in modulating the ExB vertical drift and the consequential EIA crest formation.

A passive heat tracer experiment to determine the seasonal variation in residence times in a managed aquifer recharge system with DTS

NARCIS (Netherlands)

des Tombe, B.F.; Bakker, M.; Schaars, F; van der Made, KJ; Calje, R; Borst, L.

2016-01-01

Targeted provisional session N°8.01 The seasonal variation in residence times is determined in a managed aquifer recharge system using a passive heat tracer test. The managed aquifer recharge system consists of a sequence of alternating elongated recharge basins and rows of recovery wells. The

Impact of a University-Based Outpatient Telemedicine Program on Time Savings, Travel Costs, and Environmental Pollutants.

Science.gov (United States)

Dullet, Navjit W; Geraghty, Estella M; Kaufman, Taylor; Kissee, Jamie L; King, Jesse; Dharmar, Madan; Smith, Anthony C; Marcin, James P

2017-04-01

The objective of this study was to estimate travel-related and environmental savings resulting from the use of telemedicine for outpatient specialty consultations with a university telemedicine program. The study was designed to retrospectively analyze the telemedicine consultation database at the University of California Davis Health System (UCDHS) between July 1996 and December 2013. Travel distances and travel times were calculated between the patient home, the telemedicine clinic, and the UCDHS in-person clinic. Travel cost savings and environmental impact were calculated by determining differences in mileage reimbursement rate and emissions between those incurred in attending telemedicine appointments and those that would have been incurred if a visit to the hub site had been necessary. There were 19,246 consultations identified among 11,281 unique patients. Telemedicine visits resulted in a total travel distance savings of 5,345,602 miles, a total travel time savings of 4,708,891 minutes or 8.96 years, and a total direct travel cost savings of $2,882,056. The mean per-consultation round-trip distance savings were 278 miles, average travel time savings were 245 minutes, and average cost savings were $156. Telemedicine consultations resulted in a total emissions savings of 1969 metric tons of CO 2 , 50 metric tons of CO, 3.7 metric tons of NO x , and 5.5 metric tons of volatile organic compounds. This study demonstrates the positive impact of a health system's outpatient telemedicine program on patient travel time, patient travel costs, and environmental pollutants. Copyright © 2017 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Incidence, time trends and regional variation of childhood leukaemia in Germany and Europe

International Nuclear Information System (INIS)

Kaatsch, P.; Mergenthaler, A.

2008-01-01

This paper presents data on the German and Europe-wide incidence, time trends and regional variations of childhood leukaemia. Data were provided by the German Childhood Cancer Registry (GCCR), a population-based cancer registry recording all cases of malignant diseases in children under 15 y of age residing in Germany and by the Automated Childhood Cancer Information System (ACCIS) co-ordinated at International Agency for Research on Cancer, Lyon, that combines and evaluates data from several European population-based cancer registries. The incidence of leukaemia (44.0 per million) has increased in Europe as well as in Germany in the last decades (0.6% annually on average). Germany shows no systematic aggregation of regions with low or high cancer incidence in terms of regional clustering. Incidence rates differ between European regions with the highest rates in Northern Europe (48.0 per million) and the lowest rates in Eastern Europe (39.1). Altogether, the results from ACCIS and the GCCR show good agreement. (authors)

Late time acceleration of the 3-space in a higher dimensional steady state universe in dilaton gravity

International Nuclear Information System (INIS)

Akarsu, Özgür; Dereli, Tekin

2013-01-01

We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales

Late time acceleration of the 3-space in a higher dimensional steady state universe in dilaton gravity

Science.gov (United States)

Akarsu, Özgür; Dereli, Tekin

2013-02-01

We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales.

A New Look at the Eclipse Timing Variation Diagram Analysis of Selected 3-body W UMa Systems

Science.gov (United States)

Christopoulou, P.-E.; Papageorgiou, A.

2015-07-01

The light travel effect produced by the presence of tertiary components can reveal much about the origin and evolution of over-contact binaries. Monitoring of W UMa systems over the last decade and/or the use of publicly available photometric surveys (NSVS, ASAS, etc.) has uncovered or suggested the presence of many unseen companions, which calls for an in-depth investigation of the parameters derived from cyclic period variations in order to confirm or reject the assumption of hidden companion(s). Progress in the analysis of eclipse timing variations is summarized here both from the empirical and the theoretical points of view, and a more extensive investigation of the proposed orbital parameters of third bodies is proposed. The code we have developed for this, implemented in Python, is set up to handle heuristic scanning with parameter perturbation in parameter space, and to establish realistic uncertainties from the least squares fitting. A computational example is given for TZ Boo, a W UMa system with a spectroscopically detected third component. Future options to be implemented include MCMC and bootstrapping.

RAPD-PCR and real-time PCR HRM based genetic variation evaluations of Urtica dioica parts, ecotypes and evaluations of morphotypes in Turkey.

Science.gov (United States)

Uzonur, Irem; Akdeniz, Gamze; Katmer, Zeynep; Ersoy, Seyda Karaman

2013-01-01

Urtica dioica is an ethnobotanically and medicinally important Complementary and Alternative Medicine (CAM) plant worldwide and in Turkey; 90 % of herbal CAM applications depend on it in Turkey. It has a wide range of habitats in nearly all continents. It is found in all three phytogeographical regions in Turkey (Euro-Siberian, Irano-Turanian, Mediterranean) with high adaptivity to heterogeneous geographies such as climate, soil types and altitudes. This fact in relation to the assessment of chemical constituents of the plant and combining with further genetic and morphological variation data can assist and enhance the works for the utility and reliability of CAM applications in effect and activity of this plant species. In this work we have made some preliminary experiments with novel approaches to reveal the ecotypes and genetic variation of mighty ecotypes of Urtica dioica from different phytogeographical regions of Turkey (Euro-Siberian and Mediterranean). The ecotypes have heterogeneity in both its parts (leaf, stem, root) as revealed by Random Amplified Polymorphic DNA-Polymerase Chain Reaction (RAPD-PCR) using random primers and High-resolution Melt (HRM) analysis using Urtica dioica specific primers and universal chloroplast DNA (cpDNA) primers and morphological traits such as phenolic contents and antioxidant capacities of plants' leaf infusions as used in medicinal applications in Turkey. This work will contribute a lot for the development of molecular markers to detect the genetic variation and heterogeneity of Urtica dioica to further relate with expected phenotypes that are most useful and relevant in CAM applications.

Variation Tolerant On-Chip Interconnects

CERN Document Server

Nigussie, Ethiopia Enideg

2012-01-01

This book presents design techniques, analysis and implementation of high performance and power efficient, variation tolerant on-chip interconnects.  Given the design paradigm shift to multi-core, interconnect-centric designs and the increase in sources of variability and their impact in sub-100nm technologies, this book will be an invaluable reference for anyone concerned with the design of next generation, high-performance electronics systems. Provides comprehensive, circuit-level explanation of high-performance, energy-efficient, variation-tolerant on-chip interconnect; Describes design techniques to mitigate problems caused by variation; Includes techniques for design and implementation of self-timed on-chip interconnect, delay variation insensitive communication protocols, high speed signaling techniques and circuits, bit-width independent completion detection and process, voltage and temperature variation tolerance.                          

4D RECONSTRUCTIONS FROM LOW-COUNT SPECT DATA USING DEFORMABLE MODELS WITH SMOOTH INTERIOR INTENSITY VARIATIONS

International Nuclear Information System (INIS)

Cunningham, G. S.; Lehovich, A.

2000-01-01

The Bayes Inference Engine (BIE) has been used to perform a 4D reconstruction of a first-pass radiotracer bolus distribution inside a CardioWest Total Artificial Heart, imaged with the University of Arizona's FastSPECT system. The BIE estimates parameter values that define the 3D model of the radiotracer distribution at each of 41 times spanning about two seconds. The 3D models have two components: a closed surface, composed of hi-quadratic Bezier triangular surface patches, that defines the interface between the part of the blood pool that contains radiotracer and the part that contains no radiotracer, and smooth voxel-to-voxel variations in intensity within the closed surface. Ideally, the surface estimates the ventricular wall location where the bolus is infused throughout the part of the blood pool contained by the right ventricle. The voxel-to-voxel variations are needed to model an inhomogeneously-mixed bolus. Maximum a posterior (MAP) estimates of the Bezier control points and voxel values are obtained for each time frame. We show new reconstructions using the Bezier surface models, and discuss estimates of ventricular volume as a function of time, ejection fraction, and wall motion. The computation time for our reconstruction process, which directly estimates complex 3D model parameters from the raw data, is performed in a time that is competitive with more traditional voxel-based methods (ML-EM, e.g.)

Real-Time Closed Loop Modulated Turbine Cooling

Science.gov (United States)

Shyam, Vikram; Culley, Dennis E.; Eldridge, Jeffrey; Jones, Scott; Woike, Mark; Cuy, Michael

2014-01-01

It has been noted by industry that in addition to dramatic variations of temperature over a given blade surface, blade-to-blade variations also exist despite identical design. These variations result from manufacturing variations, uneven wear and deposition over the life of the part as well as limitations in the uniformity of coolant distribution in the baseline cooling design. It is proposed to combine recent advances in optical sensing, actuation, and film cooling concepts to develop a workable active, closed-loop modulated turbine cooling system to improve by 10 to 20 the turbine thermal state over the flight mission, to improve engine life and to dramatically reduce turbine cooling air usage and aircraft fuel burn. A reduction in oxides of nitrogen (NOx) can also be achieved by using the excess coolant to improve mixing in the combustor especially for rotorcraft engines. Recent patents filed by industry and universities relate to modulating endwall cooling using valves. These schemes are complex, add weight and are limited to the endwalls. The novelty of the proposed approach is twofold 1) Fluidic diverters that have no moving parts are used to modulate cooling and can operate under a wide range of conditions and environments. 2) Real-time optical sensing to map the thermal state of the turbine has never been attempted in realistic engine conditions.

Time perspective, optimistic bias, and self-control among different statuses of university smokers in China: a cross-sectional study.

Science.gov (United States)

Xu, Ying; Yang, Yang; Ma, Xiao

2018-01-09

Risk behavior often seems 'self-defeating' to the observers. Most people understand the basic health-related knowledge, but some of them still choose to continue risk behaviors, especially for the young. This study aimed to examine time perspective, optimism bias and self control correlated with smoking behavior in Chinese college students. A cross-sectional survey enrolling 3016 university students in Chengdu City, Sichuan Province, China. Influence Factors were identified using multiple logistic regression analyses. Prevalence of current smoking was 20.92% (631 smokers), including 272 daily smokers (9.02%) and 359 non-daily smokers (11.90%). Future-oriented time perspective, general capacity for self-discipline, reliability and ethnicity were protective factors of smoking behavior. Possibility of self-suffering diseases and gender were risk factors of smoking behavior. Smoking in University of Chengdu, China is a severe problem. Results in this research have suggested that irrespective of the smoking level, improving health-related knowledge, time management awareness and self-control ability may contribute to reducing the prevalence of smoking behavior.

An eternal universe

International Nuclear Information System (INIS)

Novello, M.; Heintzmann, H.

1983-01-01

A new generalized solution of Maxwell-Einstein equations (which are non-minimally coupled) which leads to some fascinating aspects of the Universe is presented. The Cosmos has no singularity due to the coupling of longitudinal electromagnetism with space-time. It contains the Milne-Schucking cosmos as a limiting case. This model contains a free parameter (the longitudinal electromagnetic field) which allows one to fix the density of highest compression of the Cosmos. Alternativelly the parameter allows one to adjust our cosmos to the presently observed Hubble constant and the deceleration parameter. The model seems to be a viable candidate for our real cosmos as it allows one to extend the time scale of the Universe to arbitrarily large values i.e., it is able to provide the necessary time scale for the origin of life. It is speculated that the entropy is finite but intelligence in the Universe may be infinite. (Author) [pt

Universal time dependence of nighttime F region densities at high latitudes

International Nuclear Information System (INIS)

Beaujardiere, O.D.L.; Wickwar, V.B.; Caudal, G.

1985-01-01

Coordinated EISCAT, Chatanika, and Millstone Hill incoherent scatter radar observations have revealed that in the auroral zone, the nighttime F region densities vary substantially with the longitude of the observing site: EISCAT's densities are the largest and Millstone Hill's are the lowest. The nighttime F region densities measured by the individual radars are not uniform: the regions where the densities are maximum are the so-called ''blobs'' or ''patches'' that have been reported previously. The observations are consistent with the hypothesis that the nighttime densities are produced in significant amounts not by particle precipitation, but by solar EUV radiation, and that they have been transported across the polar cap. The observed differences can be explained by the offset of the geographic and geomagnetic poles. A larger portion of the magnetospheric convection pattern is sunlit when EISCAT is in the midnight sector than when Chatanika is. In winter, when Millstone Hill is in the midnight sector, almost all the auroral oval is in darkness. This universal time effect, which was observed on all coordinated three-radar experiments (September 1981 to February 1982), is illustrated using two periods of coincident radar and satellite observations: November 18--19, and December 15--16, 1981. These two periods were selected because they corresponded to relatively steady conditions. Dynamics Explorer (DE) measurements are used to aid in interpreting the radar observations. De 1 auroral images show what portion of the oval was sunlit. DE 2 data are used to measure the ion drift across the polar cap. Because the altitude of the ionization peak was high, the decay time of the F region density was substantially longer than the transit time across the polar cap

Gambling with the Universe

Science.gov (United States)

Hawking, Stephen

2002-05-01

This is an excerpt from Stephen Hawking's book The Universe in a Nutshell. Roger Penrose and Stephen Hawking, Lucasian Professor of Mathematics at the University of Cambridge, were able to show that Einstein's General Theory of Relativity implied that the universe and time itself must have had a beginning in a tremendous explosion. The discovery of the expansion of the universe is one of the great intellectual revolutions of the twentieth century.

Latitudinal cogradient variation of development time and growth rate and a negative latitudinal body weight cline in a widely distributed cabbage beetle.

Directory of Open Access Journals (Sweden)

Jianjun Tang

Full Text Available The evolutionary and phenotypic responses to environmental gradients are often assumed to be the same, a phenomenon known as "cogradient variation". However, only a few insect species display cogradient variation in physiological traits along a latitudinal gradient. We found evidence for such a response in the examination of the life history traits of the cabbage beetle Colaphellus bowringi from 6 different geographical populations at 16, 19, 22, 24, 26 and 28°C. Our results showed that larval and pupal development times significantly decreased as rearing temperature increased, and that growth rates were positively correlated with temperature. Body weight tended to decrease with increasing temperature, consistent with the general pattern in ectothermic animals. Larval development time was positively correlated with latitude, whereas the growth rate decreased as latitude increased, showing an example of latitudinal cogradient variation. Body weight significantly decreased with increasing latitude in a stepwise manner, showing a negative latitudinal body weight cline. Females were significantly larger than males, consistent with the female biased sex dimorphism in insects. Body weight tended to decrease with increasing rearing temperature, whereas the differences in sexual size dimorphism (SSD tended to decrease with increasing body weight, which biased our results toward acceptance of Rensch's rule. We found that weight loss was an important regulator of SSD, and because male pupae lost significantly more weight at metamorphosis than female pupae, SSD was greater in adults than in pupae. Overall, our data provide a new example that a latitudinal cogradient variation in physiological traits is associated with a negative latitudinal body weight cline.