Baughcum, S.L.; Henderson, S.C.; Tritz, T.G. [Boeing Co., Seattle, WA (United States)
1997-12-31
Emission inventories of fuel burned, NO{sub x}, CO, and hydrocarbons have been calculated for scheduled air traffic in 1976, 1984, 1990 and 1992 on a 1 deg latitude x 1 deg longitude x 1 km pressure altitude grid. Using this database, the seasonal variation and historical trends in aircraft emissions have been calculated for selected geographical regions (e.g., North Atlantic, Europe, North America, North Pacific). The trend in emissions is a combination of the effects of passenger demand growth, improved aircraft efficiency, changes in combustor characteristics, and aircraft size. (author) 8 refs.
Almost Periodic Time Scales and Almost Periodic Functions on Time Scales
Yongkun Li; Bing Li
2015-01-01
We propose some new concepts of almost periodic time scales and almost periodic functions on time scales and give some basic properties of these new types of almost periodic time scales and almost periodic functions on time scales. We also give some comments on a recent paper by Wang and Agarwal (2014) concerning a new almost periodic time scale.
How Sensitively Timed Are Sensitive Periods?
Zener, Rita Schaefer
2003-01-01
Reviews Maria Montessori's view of sensitive periods and examines the kinds of help needed from adults: an open mind, specific help from a prepared learning environment, and challenges presented at the right time. Stresses the universality of sensitive periods and their connection to brain development. Focuses on the unconscious nature and…
Periodicity in wide-band time series
Bullock, T.H.; McClune, M.C.; Enright, J.T.
2002-01-01
Summary: To test the hypotheses that (i) electroencephalograms (EEGs) are largely made up of oscillations at many frequencies and (ii) that the peaks in the power spectra represent oscillations, we applied a new method, called the Period Specific Average (PSA) to a wide sample of EEGs. Both hypotheses can be rejected.
On periodic orbits in discrete-time cascade systems
Huimin Li
2006-01-01
Full Text Available We present some results on existence, minimum period, number of periodic orbits, and stability of periodic orbits in discrete-time cascade systems. Some examples are presented to illustrate these results.
Review on Periodicity Mining Techniques in Time Series Data
Yogesh Malode , Rahila Patel
2012-01-01
The rapid growth in data and databases increased a need of powerful data mining technique that will guide to analyze, forecast and predict behaviour of events. Periodicity mining needs to give more attention as its increased need in real life applications. In this paper, we are going to discuss on various periodicity mining techniques in Time Series Databases as well as symbolization. Here, we propose a periodicity mining technique that will detect various periodic patterns (symbol periodici...
The Time Periodic Solution for Camassa-Holm Equation
付一平
2003-01-01
@@ 1 Introduction and Preliminaries In this paper, we are interested in one dimensional viscous Camassa-Holm equation ut-uxxt-γ(uxx-uxxxx)+3uux=uuxxx+2uxuxx+f(x,t), x∈Ω,t＞0, (1) where Ω = [0, L], γ＞ 0 is the constant viscosity and the forcing term f is ω-periodic in time t.We shall prove that under a periodic boundary condition u(x, t) is ω-periodic in the spatial variable x,Eq.(1) has a time periodic solution by using the Galerkin method and Leary-Schauder fixed point theorem (similar to the method of [4]).
Sun Wen [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China); Chen Shihua [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China)]. E-mail: shcheng@whu.edu.cn; Hong Zhiming [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China); Wang Changping [Department of Mathematics and Statistics, Dalhousie University, Halifax, NS, B3H 3J5 (Canada)
2007-08-15
A two-species periodic competition Lotka-Volterra system with time delay and diffusion is investigated. Some sufficient conditions of the existence of positive periodic solution are established for the system by using the continuation theorem of coincidence degree theory.
Controlling mobility via rapidly oscillating time-periodic stimulus
Sarkar, Prasun; Maity, Alok Kumar; Shit, Anindita; Chattopadhyay, Sudip; Chaudhuri, Jyotipratim Ray; Banik, Suman K.
2014-01-01
To address the dynamics of a Brownian particle on a periodic symmetric substrate under high-frequency periodic forcing with a vanishing time average, we construct an effective Langevin dynamics by invoking Kapitza-Landau time window. Our result is then exploited to simulate the mobility both for original and effective dynamics which are in good agreement with theoretical predictions. This close agreement and the enhancement of mobility are very robust against the tailoring of amplitude-to-fre...
Stability of periodic orbits controlled by time-delay feedback
Bleich, M E; Bleich, Michael E; Socolar, Joshua E S
1995-01-01
Extended time-delay auto-synchronization (ETDAS) is a promising technique for stabilizing unstable periodic orbits in low-dimensional dynamical systems. The technique involves continuous feedback of signals delayed by multiples of the orbit's period in a manner that is especially well-suited for fast systems and optical implementation. We show how to analyze the stability of a given implementation of ETDAS without explicit integration of time-delay equations. To illustrate the method and point out some nontrivial features of ETDAS, we obtain the domain of control for a period-one orbit of the driven, damped pendulum.
Forecasting Daily Time Series using Periodic Unobserved Components Time Series Models
Koopman, Siem Jan; Ooms, Marius
2004-01-01
We explore a periodic analysis in the context of unobserved components time series models that decompose time series into components of interest such as trend and seasonal. Periodic time series models allow dynamic characteristics to depend on the period of the year, month, week or day. In the stand
36 CFR 218.10 - Objection time periods and process.
2010-07-01
... process. 218.10 Section 218.10 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE PREDECISIONAL ADMINISTRATIVE REVIEW PROCESSES Predecisional Administrative Review Process for... Objection time periods and process. (a) Time to file an objection. Written objections, including...
Identifying multiple periodicities in sparse photon event time series
Koen, Chris
2016-07-01
The data considered are event times (e.g. photon arrival times, or the occurrence of sharp pulses). The source is multiperiodic, or the data could be multiperiodic because several unresolved sources contribute to the time series. Most events may be unobserved, either because the source is intermittent, or because some events are below the detection limit. The data may also be contaminated by spurious pulses. The problem considered is the determination of the periods in the data. A two-step procedure is proposed: in the first, a likely period is identified; in the second, events associated with this periodicity are removed from the time series. The steps are repeated until the remaining events do not exhibit any periodicity. A number of period-finding methods from the literature are reviewed, and a new maximum likelihood statistic is also introduced. It is shown that the latter is competitive compared to other techniques. The proposed methodology is tested on simulated data. Observations of two rotating radio transients are discussed, but contrary to claims in the literature, no evidence for multiperiodicity could be found.
Identifying Multiple Periodicities in Sparse Photon Event Time Series
Koen, Chris
2016-04-01
The data considered are event times (e.g. photon arrival times, or the occurrence of sharp pulses). The source is multiperiodic, or the data could be multiperiodic because several unresolved sources contribute to the time series. Most events may be unobserved, either because the source is intermittent, or because some events are below the detection limit. The data may also be contaminated by spurious pulses. The problem considered is the determination of the periods in the data. A two-step procedure is proposed: in the first, a likely period is identified; in the second, events associated with this periodicity are removed from the time series. The steps are repeated until the remaining events do not exhibit any periodicity. A number of period-finding methods from the literature are reviewed, and a new maximum likelihood statistic is also introduced. It is shown that the latter is competitive compared to other techniques. The proposed methodology is tested on simulated data. Observations of two rotating radio transients are discussed, but contrary to claims in the literature, no evidence for multiperiodicity could be found.
False periodicities in quasar time-domain surveys
Vaughan, S; Markowitz, A G; Huppenkothen, D; Middleton, M J; Alston, W N; Scargle, J D; Farr, W M
2016-01-01
There have recently been several reports of apparently periodic variations in the light curves of quasars, e.g. PG 1302-102 by Graham et al. (2015a). Any quasar showing periodic oscillations in brightness would be a strong candidate to be a close binary supermassive black hole and, in turn, a candidate for gravitational wave studies. However, normal quasars -- powered by accretion onto a single, supermassive black hole -- usually show stochastic variability over a wide range of timescales. It is therefore important to carefully assess the methods for identifying periodic candidates from among a population dominated by stochastic variability. Using a Bayesian analysis of the light curve of PG 1302-102, we find that a simple stochastic process is preferred over a sinusoidal variations. We then discuss some of the problems one encounters when searching for rare, strictly periodic signals among a large number of irregularly sampled, stochastic time series, and use simulations of quasar light curves to illustrate ...
Variable time-period optical switching: a novel OBS implementation
Jinsong Zhang(张劲松); Mingcui Cao(曹明翠); Fengguang Luo(罗风光); Tao Chen(陈涛)
2003-01-01
In this paper, we proposed a novel optical switching method based on optical burst switching (OBS), we call it variable time-period optical switching (VTPOS). It can both support circuit services and other immerged packet services. It has better usability of bandwidth, shorter offset and latency time than others of unidirectional transport signaling mechanisms for OBS. It supports deflection switching for improve blocking performance without the need of schedule buffer. It introduces a time pointer and phase indicator that made synchronous more precisely and requires less guard time, it also classifies the different services classes with a relative QoS model.
Time-periodic solutions of the Benjamin-Ono equation
Ambrose , D.M.; Wilkening, Jon
2008-04-01
We present a spectrally accurate numerical method for finding non-trivial time-periodic solutions of non-linear partial differential equations. The method is based on minimizing a functional (of the initial condition and the period) that is positive unless the solution is periodic, in which case it is zero. We solve an adjoint PDE to compute the gradient of this functional with respect to the initial condition. We include additional terms in the functional to specify the free parameters, which, in the case of the Benjamin-Ono equation, are the mean, a spatial phase, a temporal phase and the real part of one of the Fourier modes at t = 0. We use our method to study global paths of non-trivial time-periodic solutions connecting stationary and traveling waves of the Benjamin-Ono equation. As a starting guess for each path, we compute periodic solutions of the linearized problem by solving an infinite dimensional eigenvalue problem in closed form. We then use our numerical method to continue these solutions beyond the realm of linear theory until another traveling wave is reached (or until the solution blows up). By experimentation with data fitting, we identify the analytical form of the solutions on the path connecting the one-hump stationary solution to the two-hump traveling wave. We then derive exact formulas for these solutions by explicitly solving the system of ODE's governing the evolution of solitons using the ansatz suggested by the numerical simulations.
False periodicities in quasar time-domain surveys
Vaughan, S.; Uttley, P.; Markowitz, A. G.; Huppenkothen, D.; Middleton, M. J.; Alston, W. N.; Scargle, J. D.; Farr, W. M.
2016-09-01
There have recently been several reports of apparently periodic variations in the light curves of quasars, e.g. PG 1302-102 by Graham et al. Any quasar showing periodic oscillations in brightness would be a strong candidate to be a close binary supermassive black hole and, in turn, a candidate for gravitational wave studies. However, normal quasars - powered by accretion on to a single, supermassive black hole - usually show stochastic variability over a wide range of time-scales. It is therefore important to carefully assess the methods for identifying periodic candidates from among a population dominated by stochastic variability. Using a Bayesian analysis of the light curve of PG 1302-102, we find that a simple stochastic process is preferred over a sinusoidal variation. We then discuss some of the problems one encounters when searching for rare, strictly periodic signals among a large number of irregularly sampled, stochastic time series, and use simulations of quasar light curves to illustrate these points. From a few thousand simulations of steep spectrum (`red noise') stochastic processes, we find many simulations that display few-cycle periodicity like that seen in PG 1302-102. We emphasize the importance of calibrating the false positive rate when the number of targets in a search is very large.
Luo, Albert C. J.; Jin, Hanxiang
In this paper, periodic motions in a periodically excited, Duffing oscillator with a time-delayed displacement are investigated through the Fourier series, and the stability and bifurcation of such periodic motions are discussed through eigenvalue analysis. The time-delayed displacement is from the feedback control of displacement. The analytical bifurcation trees of period-1 motions to chaos in the time-delayed Duffing oscillator are presented through asymmetric period-1 to period-4 motions. Stable and unstable periodic motions are illustrated through numerical and analytical solutions. From numerical illustrations, the analytical solutions of stable and unstable period-m motions are relatively accurate with AN/m time-delay may cause discontinuity, the appropriate time-delay inputs (or initial conditions) in the initial time-delay interval should satisfy the analytical solution of periodic motions in the time-delayed dynamical systems. Otherwise, periodic motions in such a time-delayed system cannot be obtained directly.
Krylov-subspace acceleration of time periodic waveform relaxation
Lumsdaine, A. [Univ. of Notre Dame, IN (United States)
1994-12-31
In this paper the author uses Krylov-subspace techniques to accelerate the convergence of waveform relaxation applied to solving systems of first order time periodic ordinary differential equations. He considers the problem in the frequency domain and presents frequency dependent waveform GMRES (FDWGMRES), a member of a new class of frequency dependent Krylov-subspace techniques. FDWGMRES exhibits many desirable properties, including finite termination independent of the number of timesteps and, for certain problems, a convergence rate which is bounded from above by the convergence rate of GMRES applied to the static matrix problem corresponding to the linear time-invariant ODE.
Slow periodic oscillations in time domain dynamics of NO2
Sanrey, M; Sanrey, Michael; Joyeux, Marc
2007-01-01
We investigated the time domain nonadiabatic dynamics of NO2 on the coupled X2A1 and A2B2 electronic states by launching wave packets on the excited electronic state and focused on the evolution at long times (t>200 fs), which has received little attention up to now. We showed that the initial fast spreading of the wave packets is followed at all energies by slow periodic intramolecular vibronic energy redistribution (IVER) with periods in the range 0.3 to several tens of ps. These energy transfers lead to oscillations with the same periods in the population of each electronic state. Propagation of wave packets indicates that IVER frequencies also dominate the fluctuations of the squared modulus of the autocorrelation function, |A(t)|^2, at energies not too high above the bottom of the conical intersection, but that this is no longer the case at higher energies. For example, for initial wave packets prepared by almost vertical excitation of the vibrational ground state of the ground electronic surface, the os...
Mimicking Nonequilibrium Steady States with Time-Periodic Driving
Raz, Oren; Subasi, Yigit; Jarzynski, Christopher
Under static conditions, a system satisfying detailed balance generically relaxes to an equilibrium state in which there are no currents: to generate persistent currents, either detailed balance must be broken or the system must be driven in a time-dependent manner. A stationary system that violates detailed balance evolves to a nonequilibrium steady state (NESS) characterized by fixed currents. Conversely, a system that satisfies instantaneous detailed balance but is driven by the time-periodic variation of external parameters - also known as a stochastic pump (SP) - reaches a periodic state with non-vanishing currents. In both cases, these currents are maintained at the cost of entropy production. Are these two paradigmatic scenarios effectively equivalent? For discrete-state systems we establish a mapping between NESS and SP. Given a NESS characterized by a particular set of stationary probabilities, currents and entropy production rates, we show how to construct a SP with exactly the same (time-averaged) values. The mapping works in the opposite direction as well. These results establish a proof of principle: they show that SP are able to mimic the behavior of NESS, and vice-versa, within the theoretical framework of discrete-state stochastic thermodynamics.
Lagrangian structures in time-periodic vortical flows
S. V. Kostrykin
2006-01-01
Full Text Available The Lagrangian trajectories of fluid particles are experimentally studied in an oscillating four-vortex velocity field. The oscillations occur due to a loss of stability of a steady flow and result in a regular reclosure of streamlines between the vortices of the same sign. The Eulerian velocity field is visualized by tracer displacements over a short time period. The obtained data on tracer motions during a number of oscillation periods show that the Lagrangian trajectories form quasi-regular structures. The destruction of these structures is determined by two characteristic time scales: the tracers are redistributed sufficiently fast between the vortices of the same sign and much more slowly transported into the vortices of opposite sign. The observed behavior of the Lagrangian trajectories is quantitatively reproduced in a new numerical experiment with two-dimensional model of the velocity field with a small number of spatial harmonics. A qualitative interpretation of phenomena observed on the basis of the theory of adiabatic chaos in the Hamiltonian systems is given. The Lagrangian trajectories are numerically simulated under varying flow parameters. It is shown that the spatial-temporal characteristics of the Lagrangian structures depend on the properties of temporal change in the streamlines topology and on the adiabatic parameter corresponding to the flow. The condition for the occurrence of traps (the regions where the Lagrangian particles reside for a long time is obtained.
Mimicking Nonequilibrium Steady States with Time-Periodic Driving
Raz, O.; Subaşı, Y.; Jarzynski, C.
2016-04-01
Under static conditions, a system satisfying detailed balance generically relaxes to an equilibrium state in which there are no currents. To generate persistent currents, either detailed balance must be broken or the system must be driven in a time-dependent manner. A stationary system that violates detailed balance evolves to a nonequilibrium steady state (NESS) characterized by fixed currents. Conversely, a system that satisfies instantaneous detailed balance but is driven by the time-periodic variation of external parameters—also known as a stochastic pump (SP)—reaches a periodic state with nonvanishing currents. In both cases, these currents are maintained at the cost of entropy production. Are these two paradigmatic scenarios effectively equivalent? For discrete-state systems, we establish a mapping between nonequilibrium stationary states and stochastic pumps. Given a NESS characterized by a particular set of stationary probabilities, currents, and entropy production rates, we show how to construct a SP with exactly the same (time-averaged) values. The mapping works in the opposite direction as well. These results establish a proof of principle: They show that stochastic pumps are able to mimic the behavior of nonequilibrium steady states, and vice versa, within the theoretical framework of discrete-state stochastic thermodynamics. Nonequilibrium steady states and stochastic pumps are often used to model, respectively, biomolecular motors driven by chemical reactions and artificial molecular machines steered by the variation of external, macroscopic parameters. Our results loosely suggest that anything a biomolecular machine can do, an artificial molecular machine can do equally well. We illustrate this principle by showing that kinetic proofreading, a NESS mechanism that explains the low error rates in biochemical reactions, can be effectively mimicked by a constrained periodic driving.
Time-Periodic Solutions to the Navier-Stokes Equations
Kyed, Mads
2012-01-01
The three-dimensional Navier-Stokes system in the whole space with time-periodic data is investigated. Both the case of a vanishing and that of a non-vanishing velocity field at spatial infinity are treated. In the first part of the thesis, a maximal regularity framework for the linearized system is developed in a general L^q-setting. A function space with the property that the corresponding linear operator maps this space homeomorphically onto L^q is identified. Existence of a strong...
Desensitization to media violence over a short period of time.
Fanti, Kostas A; Vanman, Eric; Henrich, Christopher C; Avraamides, Marios N
2009-01-01
This study investigated the desensitization to violence over a short period of time. Participants watched nine violent movie scenes and nine comedy scenes, and reported whether they enjoyed the violent or comedy scenes and whether they felt sympathetic toward the victim of violence. Using latent growth modeling, analyses were carried out to investigate how participants responded to the different scenes across time. The findings of this study suggested that repeated exposure to media violence reduces the psychological impact of media violence in the short term, therefore desensitizing viewers to media violence. As a result, viewers tended to feel less sympathetic toward the victims of violence and actually enjoy more the violence portrayed in the media. Additionally, desensitization to media violence was better represented by a curvilinear pattern, whereas desensitization to comedy scenes was better represented by a linear pattern. Finally, trait aggression was not related to the pattern of change over time, although significant effects were found for initial reports of enjoyment and sympathy. PMID:19172659
Scheduling Periodic Real-Time Tasks with Heterogeneous Reward Requirements
Hou, I-Hong
2010-01-01
We study the problem of scheduling periodic real-time tasks so as to meet their individual minimum reward requirements. A task generates jobs that can be given arbitrary service times before their deadlines. A task then obtains rewards based on the service times received by its jobs. We show that this model is compatible to the imprecise computation models and the increasing reward with increasing service models. In contrast to previous work on these models, which mainly focus on maximize the total reward in the system, we aim to fulfill different reward requirements by different tasks, which offers better fairness and allows fine-grained tradeoff between tasks. We first derive a necessary and sufficient condition for a system, along with reward requirements of tasks, to be feasible. We also obtain an off-line feasibility optimal scheduling policy. We then studies a sufficient condition for a policy to be feasibility optimal or achieves some approximation bound. This condition can serve as a guideline for des...
Relaxation Characteristics of 828 DGEBA Epoxy Over Long Time Periods
Hoo, Jasmine; Reprogle, Riley C.; Wisler, Brian; Arechederra, Gabriel K.; McCoy, John D.; Kropka, Jamie M.; Long, Kevin N.
The mechanical relaxation response in uniaxial compression of a diglycidyl ether of bisphenol-A epoxy was studied over long time periods. The epoxy, 828DEA, was Epon 828 cured with diethanolamine (DEA). A sample was compressed at constant strain rate and held at various strain levels for days to allow the sample to relax. The sample was then compressed further and held once more. The relaxation curves were fit with a stretched exponential function. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.
Zhao, Guangyu; Ruan, Shigui
2011-01-01
We study the existence, uniqueness, and asymptotic stability of time periodic traveling wave solutions to a periodic diffusive Lotka-Volterra competition system. Under certain conditions, we prove that there exists a maximal wave speed c* such that for each wave speed c ≤ c*, there is a time periodic traveling wave connecting two semi-trivial periodic solutions of the corresponding kinetic system. It is shown that such a traveling wave is unique modulo translation and is monotone with respect...
Herrmann, Samuel; Imkeller, Peter; Peithmann, Dierk
2006-01-01
We consider potential type dynamical systems in finite dimensions with two meta-stable states. They are subject to two sources of perturbation: a slow external periodic perturbation of period $T$ and a small Gaussian random perturbation of intensity $\\epsilon$, and, therefore, are mathematically described as weakly time inhomogeneous diffusion processes. A system is in stochastic resonance, provided the small noisy perturbation is tuned in such a way that its random trajectories follow the ex...
Wang, Chao; Agarwal, Ravi P.
2016-07-01
In this paper, we improve the new concepts of almost periodic time scales addressed in 2014 to introduce the new concepts of piecewise almost periodic functions. Then we establish some first results for the existence and exponential stability of almost periodic solution for a general type of delay neural networks with impulsive effects. The approaches are based on contraction principle and Gronwall-Bellman's inequality. In addition, the numerical example and simulations are provided to illustrate our time scale methods are feasible and effective. The obtained results are more general and comprehensive than the results obtained on periodic time scales before.
False periodicities in quasar time-domain surveys
Vaughan, S.; Uttley, P.; Markowitz, A. G.; Huppenkothen, D.; Middleton, M. J.; Alston, W.N.; Scargle, J. D.; Farr, W. M.
2016-01-01
There have recently been several reports of apparently periodic variations in the light curves of quasars, e.g. PG 1302-102 by Graham et al. (2015a). Any quasar showing periodic oscillations in brightness would be a strong candidate to be a close binary supermassive black hole and, in turn, a candidate for gravitational wave studies. However, normal quasars -- powered by accretion onto a single, supermassive black hole -- usually show stochastic variability over a wide range of timescales. It...
Logic Model Checking of Time-Periodic Real-Time Systems
Florian, Mihai; Gamble, Ed; Holzmann, Gerard
2012-01-01
In this paper we report on the work we performed to extend the logic model checker SPIN with built-in support for the verification of periodic, real-time embedded software systems, as commonly used in aircraft, automobiles, and spacecraft. We first extended the SPIN verification algorithms to model priority based scheduling policies. Next, we added a library to support the modeling of periodic tasks. This library was used in a recent application of the SPIN model checker to verify the engine control software of an automobile, to study the feasibility of software triggers for unintended acceleration events.
Long-time correlations of periodic, area-preserving maps
A simple analytical decay law for correlation functions of periodic, area-preserving maps is obtained. This law is compared with numerical experiments on the standard map. The agreement between experiment and theory is good when islands are absent, but poor when islands are present. When islands are present, the correlations have a long, slowly decaying tail
Unsettled Times, Unsettled Prices: Periodical Price Survey 1997.
Ketcham, Lee; Born, Kathleen
1997-01-01
Presents the results of the thirty-seventh annual periodical price survey conducted by "Library Journal". Highlights include canceling print subscriptions and electronic journals, cost trends by subject and by countries, prices for public and school libraries and for college and medium-sized university libraries, and budgeting for 1988. (LRW)
Analysis of the Mode of the Periodically Time-varying Vibration Systems
WANG Sheng-ze; REN Ji-ge
2007-01-01
By Liapunov reducibility theorem, the periodically time-varying vibration system can be transformed to a linear time-invariant system. Based on the dynamic characteristics of the linear time-invariant system, the mode of the periodically time-varying vibration system has been discussed. The paper defines the mode and analyzes its characteristics. It can be found that the mode of the periodically time-varying system is periodically time-varing but has such characteristics as orthogonality. Finally, a method is given to solve the mode. By solving the eigenvalues and the eigenvectors of the state transition matrix in one period, the periodically time-varying mode can be obtained.
Using travel times to simulate multi-dimensional bioreactive transport in time-periodic flows
Sanz-Prat, Alicia; Lu, Chuanhe; Finkel, Michael; Cirpka, Olaf A.
2016-04-01
In travel-time models, the spatially explicit description of reactive transport is replaced by associating reactive-species concentrations with the travel time or groundwater age at all locations. These models have been shown adequate for reactive transport in river-bank filtration under steady-state flow conditions. Dynamic hydrological conditions, however, can lead to fluctuations of infiltration velocities, putting the validity of travel-time models into question. In transient flow, the local travel-time distributions change with time. We show that a modified version of travel-time based reactive transport models is valid if only the magnitude of the velocity fluctuates, whereas its spatial orientation remains constant. We simulate nonlinear, one-dimensional, bioreactive transport involving oxygen, nitrate, dissolved organic carbon, aerobic and denitrifying bacteria, considering periodic fluctuations of velocity. These fluctuations make the bioreactive system pulsate: The aerobic zone decreases at times of low velocity and increases at those of high velocity. For the case of diurnal fluctuations, the biomass concentrations cannot follow the hydrological fluctuations and a transition zone containing both aerobic and obligatory denitrifying bacteria is established, whereas a clear separation of the two types of bacteria prevails in the case of seasonal velocity fluctuations. We map the 1-D results to a heterogeneous, two-dimensional domain by means of the mean groundwater age for steady-state flow in both domains. The mapped results are compared to simulation results of spatially explicit, two-dimensional, advective-dispersive-bioreactive transport subject to the same relative fluctuations of velocity as in the one-dimensional model. The agreement between the mapped 1-D and the explicit 2-D results is excellent. We conclude that travel-time models of nonlinear bioreactive transport are adequate in systems of time-periodic flow if the flow direction does not change.
Optoelectronic timing system. Period covered: April--June 1976
Hanes, L.D.
1976-01-01
An optoelectronic timing system is being developed for the measurement of detonation front arrival times in an initiation sensitivity test currently in use at Pantex. The primary goal this quarter was the design, construction, and testing of a photodiode circuit which would have a two-nanosecond rise time response proportional to light intensity and which would have an adequate voltage output for the level of light intensity encountered in the sensitivity test. The results were satisfactory.
Scheduling periodic tasks in a hard real-time environment
Eisenbrand, Friedrich; Hähnle, Nicolai; Niemeier, Martin; SKUTELLA, Martin; Verschae, Jose; Wiese, Andreas
2010-01-01
We give a rigorous account on the complexity landscape of an important real-time scheduling problem that occurs in the design of software-based aircraft control. The goal is to distribute tasks $\\tau_i=(c_i,p_i)$ on a minimum number of identical machines and to compute offsets $a_i$ for the tasks such that no collision occurs. A task $\\tau_i$ releases a job of running time $c_i$ at each time $a_i + k\\cdot p_i$, $k\\in\\setN$ and a collision occurs if two jobs are simultaneously active on the s...
Time-Periodic Solution of a 2D Fourth-Order Nonlinear Parabolic Equation
Xiaopeng Zhao; Changchun Liu
2014-08-01
By using the Galerkin method, we study the existence and uniqueness of time-periodic generalized solutions and time-periodic classical solutions to a fourth-order nonlinear parabolic equation in 2D case.
Lorenz, Daniel S.; Reiman, Michael P.; Walker, John C.
2010-01-01
Background: Clinicians are constantly faced with the challenge of designing training programs for injured and noninjured athletes that maximize healing and optimize performance. Periodization is a concept of systematic progression—that is, resistance training programs that follow predictable patterns of change in training variables. The strength training literature is abundant with studies comparing periodization schemes on uninjured, trained, and untrained athletes. The rehabilitation litera...
26 CFR 301.7701(b)-4 - Residency time periods.
2010-04-01
... liability should be calculated in accordance with § 1.871-13 of this chapter dealing with the taxation of... continuous presence requirement. (v) Election procedure—(A) Filing requirements. An alien individual shall... tax return for the election year, the alien individual may request an extension of time for filing...
EXISTENCE OF TIME PERIODIC SOLUTIONS FOR A DAMPED GENERALIZED COUPLED NONLINEAR WAVE EQUATIONS
房少梅; 郭柏灵
2003-01-01
The time periodic solution problem of damped generalized coupled nonlinear wave equations with periodic boundary condition was studied. By using the Galerkin method to construct the approximating sequence of time periodic solutions, a priori estimate and Laray-Schauder fixed point theorem to prove the convergence of the approximate solutions, the existence of time periodic solutions for a damped generalized coupled nonlinear wave equations can be obtained.
Time-periodic solutions of the Einstein’s field equations II:geometric singularities
无
2010-01-01
In this paper,we construct several kinds of new time-periodic solutions of the vacuum Einstein’s field equations whose Riemann curvature tensors vanish,keep finite or take the infinity at some points in these space-times,respectively.The singularities of these new time-periodic solutions are investigated and some new physical phenomena are discovered.
19 CFR 351.204 - Time periods and persons examined; voluntary respondents; exclusions.
2010-04-01
... § 351.204 Time periods and persons examined; voluntary respondents; exclusions. (a) Introduction... fiscal quarters (or, in an investigation involving merchandise imported from a nonmarket economy...
Structure and dating errors in the geologic time scale and periodicity in mass extinctions
Stothers, Richard B.
1989-01-01
Structure in the geologic time scale reflects a partly paleontological origin. As a result, ages of Cenozoic and Mesozoic stage boundaries exhibit a weak 28-Myr periodicity that is similar to the strong 26-Myr periodicity detected in mass extinctions of marine life by Raup and Sepkoski. Radiometric dating errors in the geologic time scale, to which the mass extinctions are stratigraphically tied, do not necessarily lessen the likelihood of a significant periodicity in mass extinctions, but do spread the acceptable values of the period over the range 25-27 Myr for the Harland et al. time scale or 25-30 Myr for the DNAG time scale. If the Odin time scale is adopted, acceptable periods fall between 24 and 33 Myr, but are not robust against dating errors. Some indirect evidence from independently-dated flood-basalt volcanic horizons tends to favor the Odin time scale.
Measurement of a time-periodic magnetic field by rotating coil
Marusov, V.
2012-01-01
A novel technique of the measurement data processing is developed which allows to apply the rotating coil method for measurement of a dynamic magnetic field, periodic in time. The developed technique allows to obtain time-dependent multipoles in a single measurement which takes place during one power cycle of the magnet or the coil rotation period, whichever is longer.
Analytical Solutions of Time Periodic Electroosmotic Flow in a Semicircular Microchannel
Shaowei Wang
2015-01-01
Full Text Available The time periodic electroosmotic flow of Newtonian fluids through a semicircular microchannel is studied under the Debye–Hückel approximation. Analytical series of solutions are found, and they consist of a time-dependent oscillating part and a time-dependent generating or transient part. Some new physical phenomena are found. The electroosmotic flow driven by an alternating electric field is not periodic in time, but quasi-periodic. There is a phase shift between voltage and flow, which is only dependent on the frequency of external electric field.
Scattering analysis of periodic structures using finite-difference time-domain
ElMahgoub, Khaled; Elsherbeni, Atef Z
2012-01-01
Periodic structures are of great importance in electromagnetics due to their wide range of applications such as frequency selective surfaces (FSS), electromagnetic band gap (EBG) structures, periodic absorbers, meta-materials, and many others. The aim of this book is to develop efficient computational algorithms to analyze the scattering properties of various electromagnetic periodic structures using the finite-difference time-domain periodic boundary condition (FDTD/PBC) method. A new FDTD/PBC-based algorithm is introduced to analyze general skewed grid periodic structures while another algor
CHEN Wei-cheng; XU Wen-cheng
2006-01-01
Periodical polarization modulation scheme is proposed to suppress timing jitters induced by frequency fluctuations between two polarization components of solitons. In periodical polarization modulation scheme, the polarization states of the soliton are modulated to excite equally for suppressing timing jitters induced by two unequal polarization components in the soliton trapping. Moreover, polarization modulation can weaken the effect of random birefringence on the soliton pulses in each relay distance. The numerical result shows that the soliton timing jitters are suppressed by our proposed method.
Charge pumping in a quantum wire driven by a series of local time-periodic potentials
Wang, ZD; Zhu, SL
2002-01-01
We develop a method to calculate electronic transport properties through a mesoscopic scattering region in the presence of a series of time-periodic potentials. Using the method, the quantum charge pumping driven by time-periodic potentials is studied. Jumps in the pumped current are observed at the peak positions of the Wigner delay time. Our main results in both the weak pumping and strong pumping regimes are consistent with experimental results. More interestingly, we also observed the non...
Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor Blade Systems
Christensen, Rene Hardam; Santos, Ilmar
2004-01-01
overcome. Among others it is necessary, that the control scheme is capable to cope with non-linear time-varying dynamical system behaviour. However, rotating at constant speed the mathematical model becomes periodic time-variant. In this framework the present paper gives a contribution to design procedures...... results are provided to demonstrate the applicability and effectiveness of the technique. The results obtained shows that the control design technique is capable to cope with the time periodicity of this class of systems....
Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor-Blade Systems
Christensen, Rene Hardam; Santos, Ilmar
2003-01-01
overcome. Among others it is necessary, that the control scheme is capable to cope with non-linear time-varying dynamical system behaviour. However, rotating at constant speed the mathematical model becomes periodic time-variant. In this framework the present paper gives a contribution to design procedures...... results are provided to demonstrate the applicability and effectiveness of the technique. The results obtained shows that the control design technique is capable to cope with the time periodicity of this class of systems....
Chandra K Jaggi
2014-04-01
Full Text Available In this paper, a period review inventory model with controllable lead time has been considered where shortages are partially backlogged. The backorder rate is dependent on the backorder discount and the length of the protection interval, which is sum of the review period and the lead time. Two cases have been discussed for protection interval demand which are (a Demand distribution is known (Normal Distribution (b Demand distribution is unknown (Minimax distribution. Further, algorithms have been developed which jointly optimize the backorder discount, the review period and the lead time for each case. Numerical examples are also presented to illustrate the results.
Mailey, Emily L.; Gothe, Neha P.; Wójcicki, Thomas R.; Szabo, Amanda N.; Olson, Erin A.; Mullen, Sean P.; Fanning, Jason T.; Motl, Robert W.; McAuley, Edward
2013-01-01
The criteria one uses to reduce accelerometer data can profoundly influence the interpretation of research outcomes. The purpose of this study was to examine the influence of three different interruption periods (i.e., 20, 30, and 60 minutes) on the amount of data retained for analyses and estimates of sedentary time among older adults. Older adults (N=311; Mage=71.1) wore an accelerometer for seven days and reported wear time on an accelerometer log. Accelerometer data were downloaded and scored using 20, 30, and 60-minute interruption periods. Estimates of wear time derived using each interruption period were compared to self-reported wear time, and descriptive statistics were used to compare estimates of sedentary time. Results showed a longer interruption period (i.e., 60 minutes) yields the largest sample size and the closest approximation of self-reported wear time. A short interruption period (i.e., 20 minutes) is likely to underestimate sedentary time among older adults. PMID:23752299
Existence of Almost-Periodic Solutions for Lotka-Volterra Cooperative Systems with Time Delay
Kaihong Zhao
2012-01-01
Full Text Available This paper considers the existence of positive almost-periodic solutions for almost-periodic Lotka-Volterra cooperative system with time delay. By using Mawhin’s continuation theorem of coincidence degree theory, sufficient conditions for the existence of positive almost-periodic solutions are obtained. An example and its simulation figure are given to illustrate the effectiveness of our results.
Complete Periodic Synchronization of Memristor-Based Neural Networks with Time-Varying Delays
Huaiqin Wu; Luying Zhang; Sanbo Ding; Xueqing Guo; Lingling Wang
2013-01-01
This paper investigates the complete periodic synchronization of memristor-based neural networks with time-varying delays. Firstly, under the framework of Filippov solutions, by using M-matrix theory and the Mawhin-like coincidence theorem in set-valued analysis, the existence of the periodic solution for the network system is proved. Secondly, complete periodic synchronization is considered for memristor-based neural networks. According to the state-dependent switching feature of the memrist...
The existence of time-periodic stochastic motions of an incompressible fluid is obtained. Here the fluid is subject to a time-periodic body force and an additional time-periodic stochastic force that is produced by a rigid body moves periodically stochastically with the same period in the fluid
40 CFR 93.162 - Emissions beyond the time period covered by the SIP.
2010-07-01
... covered by the SIP. 93.162 Section 93.162 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 93.162 Emissions beyond the time period covered by the SIP. If a Federal action would result in total... period covered by the SIP, the Federal agency can: (a) Demonstrate conformity with the last...
One-species competition ecosystem with noise and time delay was investigated as not driven by a periodic force. The results show that the time delay is responsible for stochastic resonance of the system as delay time is smaller than critical point of the Hopf bifurcation. (general)
Zhao Ya-Hong
2010-01-01
Full Text Available We investigate the following nonlinear first-order periodic boundary value problem on time scales: , , . Some new existence criteria of positive solutions are established by using the monotone iterative technique.
liu, weiwei; Wargocki, Pawel; Xiong, Jing
2014-01-01
The present work proposed a method to determine time period of thermal adaption of occupants in naturally ventilated building, based on the relationship between their neutral temperatures and running mean outdoor air temperature. Based on the data of the field investigation, the subjects’ time pe...... with the value of the subjects in this study. The comparison shows that the occupants in China had a shorter time period of thermal adaption than European occupants, which means that Chinese occupants can adapt to a new outdoor climate condition faster....... period of thermal adaption was obtained with the proposed method. The result revealed that the subjects needed to take 4.25 days to fully adapt to a step-change in outdoor air temperature. The time period of thermal adaption for the occupants in five European countries was also calculated and compared...
Some recent results on Schrödinger equations with time-periodic potentials
Galtbayar, A.; Jensen, Arne; Yajima, K.
We report on some recent results on Schrödinger equations with time-periodic potentials. The full report on the results will be published in Galtbayar, Jensen & Yajima, J. Statist Phys.......We report on some recent results on Schrödinger equations with time-periodic potentials. The full report on the results will be published in Galtbayar, Jensen & Yajima, J. Statist Phys....
Traveling waves and spreading speeds for time-space periodic monotone systems
Fang, Jian; Yu, Xiao; Zhao, Xiao-Qiang
2015-01-01
The theory of traveling waves and spreading speeds is developed for time-space periodic monotone semiflows with monostable structure. By using traveling waves of the associated Poincar\\'e maps in a strong sense, we establish the existence of time-space periodic traveling waves and spreading speeds. We then apply these abstract results to a two species competition reaction-advection-diffusion model. It turns out that the minimal wave speed exists and coincides with the single spreading speed f...
Jaggi, Chandra K.; Haider Ali; Neetu Arneja
2014-01-01
In this paper, a period review inventory model with controllable lead time has been considered where shortages are partially backlogged. The backorder rate is dependent on the backorder discount and the length of the protection interval, which is sum of the review period and the lead time. Two cases have been discussed for protection interval demand which are (a) Demand distribution is known (Normal Distribution) (b) Demand distribution is unknown (Minimax distribution). Further, algorithms h...
Existence and Global Stability of a Periodic Solution for Discrete-Time Cellular Neural Networks
Haijian Shao
2012-01-01
Full Text Available A novel sufficient condition is developed to obtain the discrete-time analogues of cellular neural network (CNN with periodic coefficients in the three-dimensional space. Existence and global stability of a periodic solution for the discrete-time cellular neural network (DT-CNN are analysed by utilizing continuation theorem of coincidence degree theory and Lyapunov stability theory, respectively. In addition, an illustrative numerical example is presented to verify the effectiveness of the proposed results.
Stability and periodicity of solutions for delay dynamic systems on time scales
Zhi-Qiang Zhu
2014-04-01
Full Text Available This article concerns the stability and periodicity of solutions to the delay dynamic system $$ x^{\\triangle}(t=A(t x(t + F(t, x(t, x(g(t+C(t $$ on a time scale. By the inequality technique for vectors, we obtain some stability criteria for the above system. Then, by using the Horn fixed point theorem, we present some conditions under which our system is asymptotically periodic and its periodic solution is unique. In particular, the periodic solution is positive under proper assumptions.
An infinite branching hierarchy of time-periodic solutions of the Benjamin-Ono equation
Wilkening, Jon
2008-07-01
We present a new representation of solutions of the Benjamin-Ono equation that are periodic in space and time. Up to an additive constant and a Galilean transformation, each of these solutions is a previously known, multi-periodic solution; however, the new representation unifies the subset of such solutions with a fixed spatial period and a continuously varying temporal period into a single network of smooth manifolds connected together by an infinite hierarchy of bifurcations. Our representation explicitly describes the evolution of the Fourier modes of the solution as well as the particle trajectories in a meromorphic representation of these solutions; therefore, we have also solved the problem of finding periodic solutions of the ordinary differential equation governing these particles, including a description of a bifurcation mechanism for adding or removing particles without destroying periodicity. We illustrate the types of bifurcation that occur with several examples, including degenerate bifurcations not predicted by linearization about traveling waves.
Almost Periodic Solutions for Neutral-Type BAM Neural Networks with Delays on Time Scales
Yongkun Li; Li Yang
2013-01-01
Using the existence of the exponential dichotomy of linear dynamic equations on time scales, a fixed point theorem and the theory of calculus on time scales, we obtain some sufficient conditions for the existence and exponential stability of almost periodic solutions for a class of neutral-type BAM neural networks with delays on time scales. Finally, a numerical example illustrates the feasibility of our results and also shows that the continuous-time neural network and its dis...
Frederico Márcio Corrêa Vieira
2015-12-01
Full Text Available Mortality losses of broilers during pre-slaughter operations consists of actual challenge for maintaining world leadership of Brazilian poultry industry. In relation to thermal environment and its influence on abattoirs’ handling, some studies has advanced about the knowledge of these variables on poultry welfare. However, few studies was developed in subtropical conditions, considering a joint analysis of involved thermal factors. In this context, the aim of this work was to assess the mortality of broiler chickens transported throughout daily periods and submitted to different lairage time intervals. A trial was conducted in a commercial slaughterhouse at São Paulo state, during 2006. More than 13,000 loads was registered regarding broiler mortality data during pre-slaughter operations, as well as factors which had influence on losses, such as daily periods, lairage time and bioclimatic variables. Higher mortality rates of broiler transportation were registered during afternoon, around 13 birds per truck. Regarding the interaction between daily periods and lairage time at abattoir, during morning and afternoon, the mortality rate was reduced when birds were submitted to a lairage time of two hours in a controlled environment. These results showed the high level of pre-slaughter losses during hottest periods and the importance of environment control during pre-slaughter lairage of broiler chickens, with adoption of increasing time intervals when lairage environment is controlled.
Almost Periodic Solution for Memristive Neural Networks with Time-Varying Delays
Huaiqin Wu
2013-01-01
Full Text Available This paper is concerned with the dynamical stability analysis for almost periodic solution of memristive neural networks with time-varying delays. Under the framework of Filippov solutions, by applying the inequality analysis techniques, the existence and asymptotically almost periodic behavior of solutions are discussed. Based on the differential inclusions theory and Lyapunov functional approach, the stability issues of almost periodic solution are investigated, and a sufficient condition for the existence, uniqueness, and global exponential stability of the almost periodic solution is established. Moreover, as a special case, the condition which ensures the global exponential stability of a unique periodic solution is also presented for the considered memristive neural networks. Two examples are given to illustrate the validity of the theoretical results.
Research on Association with Freight Transit Period and Forwarding Time base on Logistics conditions
CHANGFENG. ZHU
2010-11-01
Full Text Available The whole process of freight forwarding includes multiple links. The consumption time of every link and its operational efficiency may affect the entire freight forwarding time, which can influence the transit period of freight, as well as the formulation and achievement of the transportation organizations scheme and the transportation contract. In order to analyze the existed problems in present calculation method of railway transit period, and the effects of logistics on forwarding time, on the basis of investigating and literature, Railway freight forwarding process and factor of logistics on railway freight forwarding time were analyzed, and average speed of through train, ordinary through train and high-speed train, and daily average running tariff kilometer and time were analyzed, and statistical results were exained by adopting 2χtesting method, finally, daily average running tariff kilometer and time of logistics developed and under-developed area were comparative analyzed, from which daily average running tariff kilometer and time were obtained. The analytical results show that the average speed, daily average running tariff kilometer and time respectively obeys normal distribution, the maximum difference value between the transit period calculated by present method and the practical forwarding time of freight is four 4.5 days, which show that the method can not objectively responds the freight forwarding time of each kind of freight transport product under logistics condition.
Mailey, Emily L; Gothe, Neha P.; Wójcicki, Thomas R.; Szabo, Amanda N.; Olson, Erin A.; Mullen, Sean P.; Fanning, Jason T.; Motl, Robert W.; McAuley, Edward
2013-01-01
The criteria one uses to reduce accelerometer data can profoundly influence the interpretation of research outcomes. The purpose of this study was to examine the influence of three different interruption periods (i.e., 20, 30, and 60 minutes) on the amount of data retained for analyses and estimates of sedentary time among older adults. Older adults (N=311; Mage=71.1) wore an accelerometer for seven days and reported wear time on an accelerometer log. Accelerometer data were downloaded and sc...
Gap solitons in parity—time complex superlattice with dual periods
A theory is presented to investigate the existence and propagation stability of gap solitons in a parity—time (PT) complex superlattice with dual periods. In this superlattice, the real and imaginary parts are both in the form of superlattices with dual periods. In the self-focusing nonlinearity, PT solitons can exist in the semi-infinite gap. However, only those gap solitons with low powers can propagate stably, whereas the high-power solitons present periodic oscillation and simultaneously suffer energy decay. In the self-defocusing nonlinearity, PT solitons only exist in the first gap and all these solitons are stable
A diffusive Fisher-KPP equation with free boundaries and time-periodic advections
Sun, Ningkui; Lou, Bendong; Zhou, Maolin
2016-01-01
We consider a reaction-diffusion-advection equation of the form: $u_t=u_{xx}-\\beta(t)u_x+f(t,u)$ for $x\\in (g(t),h(t))$, where $\\beta(t)$ is a $T$-periodic function representing the intensity of the advection, $f(t,u)$ is a Fisher-KPP type of nonlinearity, $T$-periodic in $t$, $g(t)$ and $h(t)$ are two free boundaries satisfying Stefan conditions. This equation can be used to describe the population dynamics in time-periodic environment with advection. Its homogeneous version (that is, both $...
Relative equailibria and relative periodic solutions in systems with time-delay and $S^{1}$ symmetry
Yanchuk, Serhiy
2013-01-01
We study properties of basic solutions in systems with dime delays and $S^1$-symmetry. Such basic solutions are relative equilibria (CW solutions) and relative periodic solutions (MW solutions). It follows from the previous theory that the number of CW solutions grows generically linearly with time delay $\\tau$. Here we show, in particular, that the number of relative periodic solutions grows generically as $\\tau^2$ when delay increases. Thus, in such systems, the relative periodic solutions are more abundant than relative equilibria. The results are directly applicable to, e.g., Lang-Kobayashi model for the lasers with delayed feedback. We also study stability properties of the solutions for large delays.
Fictitious Domain Technique for the Calculation of Time-Periodic Solutions of Scattering Problem
Ling Rao; Hongquan Chen
2011-01-01
The fictitious domain technique is coupled to the improved time-explicit asymptotic method for calculating time-periodic solution of wave equation. Conventionally, the practical implementation of fictitious domain method relies on finite difference time discretizations schemes and finite element approximation. Our new method applies finite difference approximations in space instead of conventional finite element approximation. We use the Dirac delta function to transport the variational forms...
An EOQ Model for Phase Inventory with Induced Demand and Periodic Cycle Time
Sujit Kumar; Shib Sankar Sana; Adrijit Goswami
2014-01-01
This paper deals with a stock flow of an inventory problem over induced demand. The inventory is consumed through “core customer” or chain marketing system in an induced environment (inductance) to exhaust all the items of the stock inventory in an indefinite time. The demand rate is depicted due to induced factor which is generated from the same inventory presented nearby. The inventory cycle time is split into several periodic times due to oscillatory feature of the inventory which is calle...
Ulker, Fatma Demet
In forward flight, helicopter rotor blades function within a highly complex aerodynamic environment that includes both near-blade and far-blade aerodynamic phenomena. These aerodynamic phenomena cause fluctuating aerodynamic loads on the rotor blades. These loads when coupled with the dynamic characteristics and elastic motion of the blade create excessive amount of vibration. These vibrations degrade helicopter performance, passenger comfort and contributes to high cost maintenance problems. In an effort to suppress helicopter vibration, recent studies have developed active control strategies using active pitch links, flaps, twist actuation and higher harmonic control of the swash plate. In active helicopter vibration control, designing a controller in a computationally efficient way requires accurate reduced-order models of complex helicopter aeroelasticity. In previous studies, controllers were designed using aeroelastic models that were obtained by coupling independently reduced aerodynamic and structural dynamic models. Unfortunately, these controllers could not satisfy stability and performance criteria when implemented in high-fidelity computer simulations or real-time experiments. In this thesis, we present a novel approach that provides accurate time-periodic reduced-order models and time-periodic H2 and H infinity controllers that satisfy the stability and performance criteria. Computational efficiency and the necessity of using the approach were validated by implementing an actively controlled flap strategy. In this proposed approach, the reduced-order models were directly identified from high-fidelity coupled aeroelastic analysis by using the time-periodic subspace identification method. Time-periodic H2 and Hinfinity controllers that update the control actuation at every time step were designed. The control synthesis problem was solved using Linear Matrix Inequality and periodic Riccati Equation based formulations, for which an in-house periodic
Scattering theory of electron transport in single layer graphene with a time-periodic potential
We applied the scattering approach to studying the transport properties of charge carriers through single layer graphene in the presence of a time-periodic potential. Using the method, expressions for the second-quantized current operator, conductivity and shot noise are obtained. The results obtained in this study demonstrate that the applied external field provides sidebands for charge carriers to tunnel through the graphene, and these sidebands changed the transport properties of the system. The results obtained in this study might be of interest to basic understanding of photon-assisted tunneling (PAT) and designers of electron devices based on graphene. - Highlights: • We study the transport properties in graphene with a time-periodic potential. • Expressions for the current operator, conductivity, shot noise are obtained. • Time-periodic potential makes the transport properties may change as a result
Stellar evolution in real time: Period variations in galactic RR Lyr stars
Poretti, E; Vandenbroere, J; Paschke, A; Klotz, A; Boër, M; Damerdji, Y; Martignoni, M; Acerbi, F
2007-01-01
The times of maximum brightness collected in the GEOS RR Lyr database allowed us to trace the period variations of a sample of 123 galactic RRab variables. These data span a time baseline exceeding 100 years. Clear evidence of period increases or decreases at constant rates has been found, suggesting evolutionary effects. The observed rates are slightly larger than those predicted by theoretical models; moreover, there is an unexpected large percentage of RRab stars showing a period decrease. The new possibilities offered by the use of robotic telecopes (TAROTs, REM) and of data from satellite (CoRoT) are expected to speed up the project to measure stellar evolution in real time. It is noteworthy that the outlines of this project have been sketched during several GEOS meetings, where the different knowledge of amateur and professional astronomers found a very profitable synthesis.
A Time-Delayed Mathematical Model for Tumor Growth with the Effect of a Periodic Therapy
Xu, Shihe; Wei, Xiangqing; Zhang, Fangwei
2016-01-01
A time-delayed mathematical model for tumor growth with the effect of periodic therapy is studied. The establishment of the model is based on the reaction-diffusion dynamics and mass conservation law and is considered with a time delay in cell proliferation process. Sufficient conditions for the global stability of tumor free equilibrium are given. We also prove that if external concentration of nutrients is large the tumor will not disappear and the conditions under which there exist periodic solutions to the model are also determined. Results are illustrated by computer simulations.
Pseudo-periodic surrogate test to sample time series in stochastic softening Duffing oscillator
Identification of typical noise-contaminated sample response is a hard task in a nonlinear system under stochastic background since irregularity of the sample response may come from measure noise, dynamical noise, or nonlinear effect, etc., and conventional dynamical methods are generally not useful. Here, the pseudo-periodic surrogate algorithm by Small is employed to test the sample time series in the softening Duffing oscillator under the Gaussian white noise excitation. The correlation dimensions of the noisy periodic and the noise-induced chaotic time series of the system are compared with those of their corresponding surrogate data respectively, the leading Lyapunov exponents by Rosenstein's algorithm are also presented for comparison
Anwesha Samanta
2015-09-01
Full Text Available The paper studies a periodic review inventory model with no shortages and different demand rates during pre- and post- deterioration periods . Deterioration of units start after a fixed time interval, and the deterioration rate is time dependent. The model determines the optimal reorder interval and the optimal order quantity so as to minimize the total cost per unit length of an inventory cycle. An extension of the model to include price discount has been further considered. Numerical examples are presented to illustrate the model and a sensitivity analysis is also reported.
Ways of spending free time by alcohol addicts during periods of drinking and rehabilitation
Dragišić-Labaš Slađana
2012-01-01
Full Text Available In the introduction we discuss free time in the context of consequences of alcoholism on social, psychological, and especially family life, then, the changing use of free time as a significant symptom of alcoholism, and finally, the new organization of free time as an important goal of social reintegration of alcoholics’ families. In the next section, we examine ways in which members of Skela Club at the “Dr Laza Lazarević” Psychiatric Hospital spend their free time during periods of drinking, and during rehabilitation and social integration. The sample consisted of 30 subjects (25 men and 5 women, aged between 25 and 65, living in Belgrade or nearby, regularly attending Club meetings and actively participating in its work. A questionnaire with 35 questions, 32 closed and 3 open, was used. The first part referred to socio-demographic variables, the second to ways of spending free time during the period of addiction, and the third part to free time at present, in the stage of abstinence and rehabilitation. During the period of drinking, subjects were mostly spending their free time in the company of other addicts, in 80% of cases. Their leisure was not very interesting, as it consisted of very few activities: sitting in a bar (76.6%, watching TV (53.3%, reading newspapers (50%, sleeping (40%. In the period of drinking a large number of subjects, regardless of gender, felt lonely - 83%. During the period of abstinence, on the contrary, leisure is better organized, the number of activities increases, and their model changes to socializing with friends (76.6%, communication with family members (66.6%, going for walks (60%, reading books (50%, listening to music (46.6%, and sport activities (36.6%. The conclusion is that alcohol addicts spent their free time during the period of drinking significantly differently than at present, when they are undergoing treatment and rehabilitation. The difference in the quality and organization of free time
Necessary N-representability Constraints from Time-reversal Symmetry for Periodic Systems
Rubin, Nicholas C
2016-01-01
The variational calculation of the two-electron reduced density matrix (2-RDM) is extended to periodic molecular systems. If the 2-RDM theory is extended to the periodic case without consideration of time-reversal symmetry, however, it can yields energies that are significantly lower than the correct energies. We derive and implement linear constraints that enforce time-reversal symmetry on the 2-RDM without destroying its computationally favorable block-diagonal structure from translational invariance. Time-reversal symmetry is distinct from space-group or spin (SU(2)) symmetries which can be expressed by unitary transformations. The time-reversal symmetry constraints are demonstrated through calculations of the metallic hydrogen chain and the one-dimensional lithium hydride crystal.
A Gaussian Process Based Online Change Detection Algorithm for Monitoring Periodic Time Series
Chandola, Varun [ORNL; Vatsavai, Raju [ORNL
2011-01-01
Online time series change detection is a critical component of many monitoring systems, such as space and air-borne remote sensing instruments, cardiac monitors, and network traffic profilers, which continuously analyze observations recorded by sensors. Data collected by such sensors typically has a periodic (seasonal) component. Most existing time series change detection methods are not directly applicable to handle such data, either because they are not designed to handle periodic time series or because they cannot operate in an online mode. We propose an online change detection algorithm which can handle periodic time series. The algorithm uses a Gaussian process based non-parametric time series prediction model and monitors the difference between the predictions and actual observations within a statistically principled control chart framework to identify changes. A key challenge in using Gaussian process in an online mode is the need to solve a large system of equations involving the associated covariance matrix which grows with every time step. The proposed algorithm exploits the special structure of the covariance matrix and can analyze a time series of length T in O(T^2) time while maintaining a O(T) memory footprint, compared to O(T^4) time and O(T^2) memory requirement of standard matrix manipulation methods. We experimentally demonstrate the superiority of the proposed algorithm over several existing time series change detection algorithms on a set of synthetic and real time series. Finally, we illustrate the effectiveness of the proposed algorithm for identifying land use land cover changes using Normalized Difference Vegetation Index (NDVI) data collected for an agricultural region in Iowa state, USA. Our algorithm is able to detect different types of changes in a NDVI validation data set (with ~80% accuracy) which occur due to crop type changes as well as disruptive changes (e.g., natural disasters).
Xinggui Liu
2011-01-01
Full Text Available In this paper, by using Mawhin's continuation theorem of coincidence degree theory, we establish the existence of at least four positive periodic solutions for a discrete time Lotka-Volterra competitive system with harvesting terms. An example is given to illustrate the effectiveness of our results.
Improving the performance of periodic real-time processes: a graph theoretical approach
Boode, Antoon H.; Broersma, Hajo; Broenink, Jan F.
2013-01-01
In this paper the performance gain obtained by combining parallel periodic real-time processes is elaborated. In certain single-core mono-processor configurations, for example embedded control systems in robotics comprising many short processes, process context switches may consume a considerable am
Zawadzka, Ewa; Domańska, Łucja
2014-01-01
A person's self-evaluation influences purposeful activity undertaken in the situation of illness. It is observed in neurological patients that limited self-awareness disturbs rehabilitation. The goal of the study was to investigate select dimensions of emotional state, the relationship between anxiety and emotional state, and the level of insight into emotional state in patients at different time periods after cerebral vascular accidents (CVAs). Sixty-five patients with short (n = 36) or long (n = 29) time periods following a stroke participated in this study. The patients' relatives (n = 65) evaluated their emotional functioning. The modified Neuropsychology Behavior and Affect Profile (NBAP; Nelson, Satz, & D'Elia, 1994 ) and State and Trait Anxiety Inventory were administered. Compared groups differed significantly in self-reporting and in relatives' reports on the NBAP scales. Patients with short and long time periods after stroke did not differ in terms of mania, indifference, depression, or inappropriateness. Significant positive moderate correlations between anxiety and depression were found in both groups. In the group with a long time period after CVA, ratings of depression, mania, indifference, and inappropriateness among patients with right-hemisphere damage were significantly correlated with their relatives' ratings. Biological and psychological factors determining emotional state and adequacy of patients' self-evaluations have also been discussed. PMID:24826501
S S Mishra; Himanshu Pandey; Singh, R. S.
2008-01-01
A probabilistic inventory model for conditional credit period with exponential demand, non-zero lead time and multiple storage facility has been developed. The behaviour of total expected cost (TEC) has been examined and the use and application of the model is demonstrated with the help of a numerical example.
S. S. Mishra
2008-01-01
Full Text Available A probabilistic inventory model for conditional credit period with exponential demand, non-zero lead time and multiple storage facility has been developed. The behaviour of total expected cost (TEC has been examined and the use and application of the model is demonstrated with the help of a numerical example.
Yepeng Xing; Qiong Wang; Valery G. Romanovski
2009-01-01
We prove several new comparison results and develop the monotone iterative tech-nique to show the existence of extremal solutions to a kind of periodic boundary value problem (PBVP) for nonlinear integro-differential equation of mixed type on time scales.
Time averaged properties along unstable periodic orbits and chaotic orbits in two map systems
Y. Saiki
2008-08-01
Full Text Available Unstable periodic orbit (UPO recently has become a keyword in analyzing complex phenomena in geophysical fluid dynamics and space physics. In this paper, sets of UPOs in low dimensional maps are theoretically or systematically found, and time averaged properties along UPOs are studied, in relation to those of chaotic orbits.
The Varying Light Curve and Timings of the Ultrashort-period Contact Binary KIC 9532219
Lee, Jae Woo; Hong, Kyeongsoo; Koo, Jae-Rim; Park, Jang-Ho
2016-03-01
KIC 9532219 is a W UMa-type eclipsing binary with an orbital period of 0.1981549 days that is below the short-period limit (˜0.22 days) of the period distribution for contact binaries. The Kepler light curve of the system exhibits striking changes in both eclipse depths and light maxima. Applying third-body and spot effects, the light-curve synthesis indicates that the eclipsing pair is currently in a marginal contact stage with a mass ratio of q = 1.20, an orbital inclination of i = 66.°0, a temperature difference of T1-T2 = 172 K, and a third light of l3 = 75.9%. To understand the light variations with time, we divided up the light curve into 312 segments and analyzed them separately. The results reveal that variation of eclipse depth is primarily caused by changing amounts of contamination due to the nearby star KIC 9532228 between the Kepler Quarters and that the variable O’Connell effect originates from the starspot activity on the less massive primary component. Based on our light-curve timings, a period study of KIC 9532219 indicates that the orbital period has varied as a combination of a downward parabola and a light-travel-time (LTT) effect due to a third body, which has a period of 1196 days and a minimum mass of 0.0892 M⊙ in an orbit of eccentricity 0.150. The parabolic variation could be a small part of a second LTT orbit due to a fourth component in a wider orbit, instead of either mass transfer or angular momentum loss.
Stochastic analog reactor period - time achievement a given level of number of neutrons
In theory and in practice the operation of nuclear reactors to control the safety of the reactor is widely used the deterministic value of period of the reactor. It is proposed along with the period of the reactor using a stochastic analogue of this magnitude - a random value of time to achieve a given level of a random process for the number of neutrons in the reactor. Thr paper discusses various models for the distribution function of the lifetime of neutrons in the reactor, the knowledge which is important in the study of time to achieve the level and impact of the maximum possible time to achieve the level of the characteristics of the random variable
Kerr, M.; Hobbs, G.; Johnston, S.; Shannon, R. M.
2016-01-01
In a search for periodic variation in the arrival times of pulses from 151 young, energetic pulsars, we have identified seven cases of modulation consistent with one or two harmonics of a single fundamental with time-scale 0.5-1.5 yr. We use simulations to show that these modulations are statistically significant and of high quality (sinusoidal) even when contaminated by the strong stochastic timing noise common to young pulsars. Although planetary companions could induce such modulation, the large implied masses and 2:1 mean motion resonances challenge such an explanation. Instead, the modulation is likely to be intrinsic to the pulsar, arising from quasi-periodic switching between stable magnetospheric states, and we propose that precession of the neutron star may regulate this switching.
Stochastic analog reactor period - time achievement a given level of number of neutrons
In theory and in practice the operation of nuclear reactors to control the safety of the reactor is widely used the deterministic value of period of the reactor. It is proposed along with the period of the reactor using a stochastic analogue of this magnitude - a random value of time to achieve a given level of a random process for the number of neutrons in the reactor. The paper discusses various models for the distribution function of the lifetime of neutrons in the reactor, the knowledge which is important in the study of time to achieve the level and impact of the maximum possible time to achieve the level of the characteristics of the random variable
Time to reach a given level of number of neutrons is stochastic analog of reactor period
In theory and in practice the operation of nuclear reactors to control the safety of the reactor is widely used deterministic value - the period of the reactor. It is proposed along with the period of the reactor using a stochastic analogue of this magnitude - a random amount of time to achieve a given level of a random process for the number of neutrons in the reactor. The paper discusses various features of the behavior of the mean and variance of time to achieve a specified level. This kind of features can be associated with impaired behavior of the reactor system. Introduced the value of time required to reach the level can be used to monitor and improve the safety of nuclear power plants
Kerr, Matthew; Johnston, Simon; Shannon, Ryan
2015-01-01
In a search for periodic variation in the arrival times of pulses from 151 young, energetic pulsars, we have identified seven cases of modulation consistent with one or two harmonics of a single fundamental with time-scale 0.5-1.5 yr. We use simulations to show that these modulations are statistically significant and of high quality (sinusoidal) even when contaminated by the strong stochastic timing noise common to young pulsars. Although planetary companions could induce such modulation, the large implied masses and 2:1 mean motion resonances challenge such an explanation. Instead, the modulation is likely to be intrinsic to the pulsar, arising from quasi-periodic switching between stable magnetospheric states, and we propose that precession of the neutron star may regulate this switching.
Storing quantum information in XXZ spin rings with periodically time-controlled interactions
We introduce a general scheme to realize massive quantum memories in simple systems of interacting qubits. Such systems are described by spin rings with XXZ intersite couplings of suitably time-periodically controlled amplitudes. We show that initially localized excitations undergo perfect periodic revivals, allowing for the simultaneous storage of arbitrary sets of different local states. This novel approach to the problem of storing quantum information hints at a new way to control and suppress the effect of decoherence on a quantum computer realized in a system with nonvanishing interactions between the constituent qubits
Storing quantum information in XXZ spin rings with periodically time-controlled interactions
Giampaolo, S M; Illuminati, F; Mazzarella, G [Dipartimento di Fisica ' E. R. Caianiello' , Universita di Salerno, INFM UdR di Salerno, INFN Sezione di Napoli, Gruppo Collegato di Salerno, Via S. Allende, 84081 Baronissi, SA (Italy)
2005-10-01
We introduce a general scheme to realize massive quantum memories in simple systems of interacting qubits. Such systems are described by spin rings with XXZ intersite couplings of suitably time-periodically controlled amplitudes. We show that initially localized excitations undergo perfect periodic revivals, allowing for the simultaneous storage of arbitrary sets of different local states. This novel approach to the problem of storing quantum information hints at a new way to control and suppress the effect of decoherence on a quantum computer realized in a system with nonvanishing interactions between the constituent qubits.
A General Approach to Time Periodic Incompressible Viscous Fluid Flow Problems
Geissert, Matthias; Hieber, Matthias; Nguyen, Thieu Huy
2016-06-01
This article develops a general approach to time periodic incompressible fluid flow problems and semilinear evolution equations. It yields, on the one hand, a unified approach to various classical problems in incompressible fluid flow and, on the other hand, gives new results for periodic solutions to the Navier-Stokes-Oseen flow, the Navier-Stokes flow past rotating obstacles, and, in the geophysical setting, for Ornstein-Uhlenbeck and various diffusion equations with rough coefficients. The method is based on a combination of interpolation and topological arguments, as well as on the smoothing properties of the linearized equation.
In this paper, we study the phenomenon of stochastic resonance (SR) in a periodically driven bistable system with correlations between multiplicative and additive white noise terms when there are two different kinds of time delays existed in the deterministic and fluctuating forces, respectively. Using the small time delay approximation and the theory of signal-to-noise ratio (SNR) in the adiabatic limit, the expression of SNR is obtained. The effects of the delay time τ in the deterministic force, and the delay time θ in the fluctuating force on SNR are discussed. Based on the numerical computation, it is found that: (i) There appears a reentrant transition between one peak and two peaks and then to one peak again in the curve of SNR when the value of the time delay θ is increased. (ii) SR can be realized by tuning the time delay τ or θ with fixed noise, i.e., delay-induced stochastic resonance (DSR) exists. (general)
Plasticity of the intrinsic period of the human circadian timing system.
Frank A J L Scheer
Full Text Available Human expeditions to Mars will require adaptation to the 24.65-h Martian solar day-night cycle (sol, which is outside the range of entrainment of the human circadian pacemaker under lighting intensities to which astronauts are typically exposed. Failure to entrain the circadian time-keeping system to the desired rest-activity cycle disturbs sleep and impairs cognitive function. Furthermore, differences between the intrinsic circadian period and Earth's 24-h light-dark cycle underlie human circadian rhythm sleep disorders, such as advanced sleep phase disorder and non-24-hour sleep-wake disorders. Therefore, first, we tested whether exposure to a model-based lighting regimen would entrain the human circadian pacemaker at a normal phase angle to the 24.65-h Martian sol and to the 23.5-h day length often required of astronauts during short duration space exploration. Second, we tested here whether such prior entrainment to non-24-h light-dark cycles would lead to subsequent modification of the intrinsic period of the human circadian timing system. Here we show that exposure to moderately bright light ( approximately 450 lux; approximately 1.2 W/m(2 for the second or first half of the scheduled wake episode is effective for entraining individuals to the 24.65-h Martian sol and a 23.5-h day length, respectively. Estimations of the circadian periods of plasma melatonin, plasma cortisol, and core body temperature rhythms collected under forced desynchrony protocols revealed that the intrinsic circadian period of the human circadian pacemaker was significantly longer following entrainment to the Martian sol as compared to following entrainment to the 23.5-h day. The latter finding of after-effects of entrainment reveals for the first time plasticity of the period of the human circadian timing system. Both findings have important implications for the treatment of circadian rhythm sleep disorders and human space exploration.
Complete Periodic Synchronization of Memristor-Based Neural Networks with Time-Varying Delays
Huaiqin Wu
2013-01-01
Full Text Available This paper investigates the complete periodic synchronization of memristor-based neural networks with time-varying delays. Firstly, under the framework of Filippov solutions, by using M-matrix theory and the Mawhin-like coincidence theorem in set-valued analysis, the existence of the periodic solution for the network system is proved. Secondly, complete periodic synchronization is considered for memristor-based neural networks. According to the state-dependent switching feature of the memristor, the error system is divided into four cases. Adaptive controller is designed such that the considered model can realize global asymptotical synchronization. Finally, an illustrative example is given to demonstrate the validity of the theoretical results.
Stability and attractivity of periodic solutions of parabolic systems with time delays
Pao, C. V.
2005-04-01
This paper is concerned with the existence, stability, and global attractivity of time-periodic solutions for a class of coupled parabolic equations in a bounded domain. The problem under consideration includes coupled system of parabolic and ordinary differential equations, and time delays may appear in the nonlinear reaction functions. Our approach to the problem is by the method of upper and lower solutions and its associated monotone iterations. The existence of time-periodic solutions is for a class of locally Lipschitz continuous reaction functions without any quasimonotone requirement using Schauder fixed point theorem, while the stability and attractivity analysis is for quasimonotone nondecreasing and mixed quasimonotone reaction functions using the monotone iterative scheme. The results for the general system are applied to the standard parabolic equations without time delay and to the corresponding ordinary differential system. Applications are also given to three Lotka-Volterra reaction diffusion model problems, and in each problem a sufficient condition on the reaction rates is obtained to ensure the stability and global attractivity of positive periodic solutions.
Safe decommissioning of units 1 and 2 of Kozloduy NPP: selection of safe enclosure time period
The time period foreseen for Safe Enclosure is internationally varying from 30 years to 100 years. A SE period of about 70 years was considered for Kozloduy NPP, prior to start the development of 'Technical Design for the Decommissioning of Kozloduy Units 1 and 2' and detailed assessment of all factors which have influence on the SE duration. This paper shows that, on the basis of the analysis performed in the project, for safety, technological and economical reasons it is possible to reduce Kozloduy NPP SE time to 35 years. The following factors have been analysed: The radioactive decay: the surface and mass contamination acceptance criteria enabling to achieve the European Community requirements for free release level remain practically constant for a SE period .35 years. There is thus no benefit in term of decontamination factor reduction, to extend the SE period beyond 35 years. Similarly 35 years after the reactor final shut down, the . dose rate of the primary circuit will drop below 3 μSv/h and will become then negligible. From the health physics and decommissioning standpoints, there is no benefit in extending the SE period beyond 35 years. Costs and investments: After the reactor final shutdown and during the SE, some systems and equipment will remain in operation to ensure the safe conditions of the nuclear buildings: ventilation, radiation monitoring, fire protection etc. The costs associated to the maintenance and repair and in some cases to the replacement of these equipment as well as the surveillance costs will be reduced. Similarly, the costs associated to the maintenance and repair of the civil engineering structures, including their structural integrity and confining capabilities will also be reduced. The duration of SE time is also bounded to the possibilities to raise the needed funds for the decommissioning
Stochastic resonance in a time-delayed asymmetric bistable system with mixed periodic signal
This paper studies the phenomenon of stochastic resonance in an asymmetric bistable system with time-delayed feedback and mixed periodic signal by using the theory of signal-to-noise ratio in the adiabatic limit. A general approximate Fokker–Planck equation and the expression of the signal-to-noise ratio are derived through the small time delay approximation at both fundamental harmonics and mixed harmonics. The effects of the additive noise intensity Q, multiplicative noise intensity D, static asymmetry r and delay time τ on the signal-to-noise ratio are discussed. It is found that the higher mixed harmonics and the static asymmetry r can restrain stochastic resonance, and the delay time τ can enhance stochastic resonance. Moreover, the longer the delay time τ is, the larger the additive noise intensity Q and the multiplicative noise intensity D are, when the stochastic resonance appears. (general)
We investigate the tunneling time (dwell time) in periodic diluted-magnetic-semiconductor/nonmagnetic-barrier (DMS/NB) superlattices subjected to an external magnetic field. It is found that spin-dependent resonant bands form in the spectra of dwell time, which can be effectively manipulated by not only the external magnetic field but also the geometric parameters of the system. Moreover, an intuitive semiclassical delay is defined to illustrate the behavior of the dwell time, and the former one is shown to be the result of “smoothing out” the latter one. We also find that the dwell time in diluted-magnetic-semiconductor/semiconductor superlattices behaves surprisingly different from the DMS/NB case, especially for spin-down electrons
Yang, Ping-Fan; Guo, Yong
2016-02-01
We investigate the tunneling time (dwell time) in periodic diluted-magnetic-semiconductor/nonmagnetic-barrier (DMS/NB) superlattices subjected to an external magnetic field. It is found that spin-dependent resonant bands form in the spectra of dwell time, which can be effectively manipulated by not only the external magnetic field but also the geometric parameters of the system. Moreover, an intuitive semiclassical delay is defined to illustrate the behavior of the dwell time, and the former one is shown to be the result of "smoothing out" the latter one. We also find that the dwell time in diluted-magnetic-semiconductor/semiconductor superlattices behaves surprisingly different from the DMS/NB case, especially for spin-down electrons.
Yang, Ping-Fan; Guo, Yong, E-mail: guoy66@tsinghua.edu.cn [Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)
2016-02-01
We investigate the tunneling time (dwell time) in periodic diluted-magnetic-semiconductor/nonmagnetic-barrier (DMS/NB) superlattices subjected to an external magnetic field. It is found that spin-dependent resonant bands form in the spectra of dwell time, which can be effectively manipulated by not only the external magnetic field but also the geometric parameters of the system. Moreover, an intuitive semiclassical delay is defined to illustrate the behavior of the dwell time, and the former one is shown to be the result of “smoothing out” the latter one. We also find that the dwell time in diluted-magnetic-semiconductor/semiconductor superlattices behaves surprisingly different from the DMS/NB case, especially for spin-down electrons.
Infrared Time Lags for the Periodic Quasar PG 1302-102
Jun, Hyunsung D; Graham, Matthew J; Djorgovski, S G; Mainzer, Amy; Cutri, Roc M; Drake, Andrew J; Mahabal, Ashish A
2015-01-01
The optical light curve of the quasar PG 1302-102 at $z = 0.278$ shows a strong, smooth 5.2 yr periodic signal, detectable over a period of $\\sim 20$ yr. Although the interpretation of this phenomenon is still uncertain, the most plausible mechanisms involve a binary system of two supermassive black holes with a subparsec separation. At this close separation, the nuclear black holes in PG 1302-102 will likely merge within $\\sim 10^{5}$ yr due to gravitational wave emission alone. Here we report the rest-frame near-infrared time lags for PG 1302-102. Compiling data from {\\it WISE} and {\\it Akari}, we confirm that the periodic behavior reported in the optical light curve from Graham et al. (2015) is reproduced at infrared wavelengths, with best-fit observed-frame 3.4 and $4.6 \\mu$m time lags of $(2219 \\pm 153, 2408 \\pm 148)$ days for a near face-on orientation of the torus, or $(4103\\pm 153, 4292 \\pm 148)$ days for an inclined system with relativistic Doppler boosting in effect. The periodicity in the infrared ...
Huang, Zhu
2015-03-01
The periodic unsteady natural convection flow and heat transfer in a square enclosure containing a concentric circular cylinder is numerically studied. The temperature of the inner circular cylinder fluctuates periodically with time at higher averaged value while the temperature of the enclosure keeps lower constant, and the natural convection is driven by the temperature difference. The two-dimensional natural convection is simulated with high accuracy temporal spectral method and local radial basis functions method. The Rayleigh number is studied in the range 103 ≤ Ra ≤ 106, the temperature pulsating period ranges from 0.01 to 100 and the temperature pulsating amplitudes are a = 0.5, 1.0 and 1.5. Numerical results reveal that the fluid flow and heat transfer is strongly dependent on the pulsating temperature of inner cylinder. Comparing with the steady state natural convection, the heat transfer is enhanced generally for the time-periodic unsteady natural convection, and the local maximum heat transfer rate is observed for Ra = 105 and 106. Moreover, the phenomenon of backward heat transfer is discussed quantitatively. Also, the influence of pulsating temperature on the unsteady fluid flow and heat transfer are discussed and analyzed.
An EOQ Model for Phase Inventory with Induced Demand and Periodic Cycle Time
Sujit Kumar De
2014-01-01
Full Text Available This paper deals with a stock flow of an inventory problem over induced demand. The inventory is consumed through “core customer” or chain marketing system in an induced environment (inductance to exhaust all the items of the stock inventory in an indefinite time. The demand rate is depicted due to induced factor which is generated from the same inventory presented nearby. The inventory cycle time is split into several periodic times due to oscillatory feature of the inventory which is called phase inventory. Considering uniform demand, this cycle time splits into two basic parts, namely, “first shift” (phase and “second shift” (phase. Since the process dampens over time, so the whole inventory will exhaust after few periods. A cost function consisted of inventory cost, setup cost, and loss for induced items is minimized to obtain optimal order quantity and replenishment time. The multivariate lagrange interpolation (MLI over the average values of the postsensitivity analysis is developed here. Finally, graphical illustrations are made to justify the model.
Özlem Acar
2016-01-01
Full Text Available OBJECTIVE: The aim of this study was to determine whether different rinsing time periods affected the wettability of polymerized elastomeric impression materials. MATERIALS AND METHOD: Panasil Contact Plus (PCP, Panasil Contact Non-Surfactant (PCNS, Panasil Initial Contact (PIC, Express (EXP and Impregum (IMP impression materials were tested. Standardized samples were rinsed with water for 10 s, 15 s or 20 s, and the wettability was determined by contact angle measurement through an evaluation period of 60 seconds (n=7. Non-rinsed groups were used as control. Measurements were made at 5 time points (at 0, 6, 15, 30 and 60 seconds. Kruskal Wallis test and Conover’s multiple comparison tests were used for all multiple comparisons. Bonferroni adjustment was applied for controlling Type I error (p0.002. CONCLUSION: Rinsing the surfactant-containing polyvinylsiloxane impression materials decreased their wettability, whereas no such effect was seen for the surfactant free polyvinylsiloxane and polyether impression materials.
Periodic solutions of a nonautonomous predator-prey system with stage structure and time delays
Xu, Rui; Wang, Zhiqiang
2006-11-01
A nonautonomous Lotka-Volterra type predator-prey model with stage structure and time delays is investigated. It is assumed in the model that the individuals in each species may belong to one of two classes: the immatures and the matures, the age to maturity is presented by a time delay, and that the immature predators do not feed on prey and do not have the ability to reproduce. By some comparison arguments we first discuss the permanence of the model. By using the continuation theorem of coincidence degree theory, sufficient conditions are derived for the existence of positive periodic solutions to the model. By means of a suitable Lyapunov functional, sufficient conditions are obtained for the uniqueness and global stability of the positive periodic solutions to the model.
With the aim of formulating a method to control dynamic phase transitions in periodically driven bistable systems with reversal symmetry, a time-delayed feedback control method to stabilize an unstable periodic orbit in the broken symmetric regime is studied. In order to overcome a limitation of the conventional time-delayed feedback method, another extended scheme is proposed, and its improved ability with respect to stabilization is proved. Through the linear stability analysis of model controlled systems driven by sinusoidal fields, basic differences between the conventional and proposed methods are extracted. It is clarified that a few characteristics around the bifurcation point from the pitchfork critical branch to the Hopf branch and the turning point of the Hopf critical branch classify essential features of the stability diagram and concern restrictions for stabilization. Within the linear stability treatment, this paper estimates a safe choice and an effective range of feedback gains in the proposed method. (author)
Tracing temperature in a nanometer size region in a picosecond time period.
Nakajima, Kaoru; Kitayama, Takumi; Hayashi, Hiroaki; Matsuda, Makoto; Sataka, Masao; Tsujimoto, Masahiko; Toulemonde, Marcel; Bouffard, Serge; Kimura, Kenji
2015-01-01
Irradiation of materials with either swift heavy ions or slow highly charged ions leads to ultrafast heating on a timescale of several picosecond in a region of several nanometer. This ultrafast local heating result in formation of nanostructures, which provide a number of potential applications in nanotechnologies. These nanostructures are believed to be formed when the local temperature rises beyond the melting or boiling point of the material. Conventional techniques, however, are not applicable to measure temperature in such a localized region in a short time period. Here, we propose a novel method for tracing temperature in a nanometer region in a picosecond time period by utilizing desorption of gold nanoparticles around the ion impact position. The feasibility is examined by comparing with the temperature evolution predicted by a theoretical model. PMID:26293488
Is the use of underwater polarized light by fish restricted to crepuscular time periods?
Novales Flamarique, I; Hawryshyn, C W
1997-04-01
We measured the spectral distributions of the underwater total and polarized light fields in the upper photic zone of meso-eutrophic waters (i.e., blue-green waters containing medium to high chlorophyll a concentrations). Per cent polarization levels during the day were always lower than 40%, but at crepuscular times these values could increase to 67%. A corresponding change occurred in the spectral distribution, with proportionately more shorter wavelength photons contributing to the total spectrum during crepuscular periods. Electrophysiological recordings from the optic nerve of rainbow trout subjected to light stimuli of varying polarization percentages show that the animal's threshold for detecting polarized light is between 63 and 72%. These physiological findings suggest that the use of water-induced polarized light cues by rainbow trout and similar percomorph fish should be restricted to crepuscular time periods. PMID:9196717
Sobolev type equations of time-fractional order with periodical boundary conditions
Plekhanova, Marina
2016-08-01
The existence of a unique local solution for a class of time-fractional Sobolev type partial differential equations endowed by the Cauchy initial conditions and periodical with respect to every spatial variable boundary conditions on a parallelepiped is proved. General results are applied to study of the unique solvability for the initial boundary value problem to Benjamin-Bona-Mahony-Burgers and Allair partial differential equations.
A Coupled Far-Field Formulation for Time-Periodic Numerical Problems in Fluid Dynamics
Edmund Chadwick; Rabea El-Mazuzi
2012-11-01
Consider uniform flow past an oscillating body generating a time-periodic motion in an exterior domain, modelled by a numerical fluid dynamics solver in the near field around the body. A far-field formulation, based on the Oseen equations, is presented for coupling onto this domain thereby enabling the whole space to be modelled. In particular, examples for formulations by boundary elements and infinite elements are described.
Periodic review base-stock replenishment policy with endogenous lead times
Boute, Robert; Lambrecht, Marc; Van Houdt, B
2004-01-01
In this paper, we consider a two stage supply chain where the retailer's inventory is controlled by the periodic review, base-stock level (R,S) replenishment policy and the replenishment lead times are endogenously generated by the manufacturer's production system with finite capacity. We extend the work of Benjaafar and Kim (2004) who study the effect of demand variability in a continuously reviewed base-stock policy with single unit demands. In our analysis, we allow for demand in batches o...
Time-periodic solutions to the full Navier–Stokes–Fourier system
Feireisl, Eduard; Mucha, P.; Novotný, A.; Pokorný, M.
2012-01-01
Roč. 204, č. 3 (2012), s. 745-786. ISSN 0003-9527 R&D Projects: GA ČR GA201/09/0917; GA MŠk LC06052 Institutional research plan: CEZ:AV0Z10190503 Keywords : compressible Navier–Stokes–Fourier system * time-periodic solution * weak solution Subject RIV: BA - General Mathematics Impact factor: 2.292, year: 2012 http://www.springerlink.com/content/3t5r85w616158561/
Electron Transport in Graphene-Based Double-Barrier Structure under a Time Periodic Field
LU Wei-Tao; WANG Shun-Jin
2011-01-01
The transport property of electron through graphene-based double-barrier under a time periodic field is investigated. We study the influence of the system parameters and external field strength on the transmission probability.The results show that transmission exhibits various kinds of behavior with the change of parameters due to its angular anisotropy. One could control the values of transmission and conductivity as well as their distribution in each band by tuning the parameters.
Y. Saiki
2007-09-01
Full Text Available An infinite number of unstable periodic orbits (UPOs are embedded in a chaotic system which models some complex phenomenon. Several algorithms which extract UPOs numerically from continuous-time chaotic systems have been proposed. In this article the damped Newton-Raphson-Mees algorithm is reviewed, and some important techniques and remarks concerning the practical numerical computations are exemplified by employing the Lorenz system.
Zhang, Shangbin; Lu, Siliang; He, Qingbo; Kong, Fanrang
2016-09-01
For rotating machines, the defective faults of bearings generally are represented as periodic transient impulses in acquired signals. The extraction of transient features from signals has been a key issue for fault diagnosis. However, the background noise reduces identification performance of periodic faults in practice. This paper proposes a time-varying singular value decomposition (TSVD) method to enhance the identification of periodic faults. The proposed method is inspired by the sliding window method. By applying singular value decomposition (SVD) to the signal under a sliding window, we can obtain a time-varying singular value matrix (TSVM). Each column in the TSVM is occupied by the singular values of the corresponding sliding window, and each row represents the intrinsic structure of the raw signal, namely time-singular-value-sequence (TSVS). Theoretical and experimental analyses show that the frequency of TSVS is exactly twice that of the corresponding intrinsic structure. Moreover, the signal-to-noise ratio (SNR) of TSVS is improved significantly in comparison with the raw signal. The proposed method takes advantages of the TSVS in noise suppression and feature extraction to enhance fault frequency for diagnosis. The effectiveness of the TSVD is verified by means of simulation studies and applications to diagnosis of bearing faults. Results indicate that the proposed method is superior to traditional methods for bearing fault diagnosis.
Periodic Time-Domain Nonlocal Nonreflecting Boundary Conditions for Duct Acoustics
Watson, Willie R.; Zorumski, William E.
1996-01-01
Periodic time-domain boundary conditions are formulated for direct numerical simulation of acoustic waves in ducts without flow. Well-developed frequency-domain boundary conditions are transformed into the time domain. The formulation is presented here in one space dimension and time; however, this formulation has an advantage in that its extension to variable-area, higher dimensional, and acoustically treated ducts is rigorous and straightforward. The boundary condition simulates a nonreflecting wave field in an infinite uniform duct and is implemented by impulse-response operators that are applied at the boundary of the computational domain. These operators are generated by convolution integrals of the corresponding frequency-domain operators. The acoustic solution is obtained by advancing the Euler equations to a periodic state with the MacCormack scheme. The MacCormack scheme utilizes the boundary condition to limit the computational space and preserve the radiation boundary condition. The success of the boundary condition is attributed to the fact that it is nonreflecting to periodic acoustic waves. In addition, transient waves can pass rapidly out of the solution domain. The boundary condition is tested for a pure tone and a multitone source in a linear setting. The effects of various initial conditions are assessed. Computational solutions with the boundary condition are consistent with the known solutions for nonreflecting wave fields in an infinite uniform duct.
Time-frequency manifold correlation matching for periodic fault identification in rotating machines
He, Qingbo; Wang, Xiangxiang
2013-05-01
For rotating machines, the localized faults of key components generally represent as periodic transient impulses in vibration signals. The existence of background noise will corrupt transient impulses in practice, and will thus increase the difficulty to identify specific faults. This paper combines the concepts of time-frequency manifold (TFM) and image template matching, and proposes a novel TFM correlation matching method to enhance identification of the periodic faults. This method is to conduct correlation matching of a vibration signal in the time-frequency domain by using the TFM with a short duration as a template. By this method, the time-frequency distribution (TFD) of a vibration signal is firstly achieved by the Smoothed Pseudo-Wigner-Ville distribution (SPWVD) method. Then the TFM template is learned to do correlation matching with the TFD of the analyzed signal. Finally, the ridge is extracted from the correlation matching image and the ridge coefficients are analyzed for periodic fault identification. The proposed method takes advantages of the TFM in noise suppression and template matching in object enhancement, and can enhance the fault impulses of interest in a unified scale. The novel method is verified to be superior to traditional enveloping method with providing smoother and clearer fault impulse component via applications to gearbox fault detection and bearing defect identification.
Passive climate control in Spanish office buildings for long periods of time
Orosa, J.A.; Baalina, A. [Departamento de Energia y P, Escuela Tecnica Superior de N. y M., Universidade da Coruna, Paseo de Ronda 51, P.C.: 1501 A Coruna (Spain)
2008-12-15
Recent studies have shown that the effect of the internal wall coating on an indoor thermal environment can be seen for short periods of time [Hameury S. Moisture buffering capacity of heavy timber structures directly exposed to an indoor climate: a numerical study. Building and Environment 2005;40(10):1400-12]. However, for long periods of time this effect is hidden by the air renovation and vapour release. These passive methods are gaining popularity because they are energy conscious and environmentally friendly. However, there is little published data on mass transfer between building envelopes and indoor air [Simonson CJ, Salonvaara MH. Mass transfer between indoor air and a porous building envelope: part I - field measurements. In: Proceedings of healthy buildings, vol. 3, 2000; Simonson CJ, Tuomo O. Moisture performance of buildings envelopes with no plastic vapour retarders in cold climates. In: Proceedings of healthy buildings, vol. 3, 2000]. The main objective of this study is to show the internal wall coating effect on indoor air conditions by means of the indoor air parameters. These measurements were taken in 25 office buildings during different seasons. Our results will allow us to understand the internal coating effect for long and short periods of time and, therefore, the thermal comfort and indoor air quality conditions. (author)
EFFECT OF MAGNETIZATION OF WATER ON INDUCTION TIME AND GROWTH PERIOD OF NATURAL GAS HYDRATE
KUANG Li; FAN Shuanshi
2003-01-01
The effect of diluted solution's magnetization on induction time and growth period of natural gas hydrate (NGH) has been investigated in quiescent reaction system at pressure of 4. 5 MPa and temperature of 274 K with SDS as surfactant, by using volume fixed and pressure falling method. Experimental results show that magnetization will have effect on the induction time of NGH. After magnetization with magnetic field intensity of 0.33 T, the induction time of NGH has been reduced to 47 min (average) from 99 min (average) in which there is no magnetization. On the other hand, the induction time has been prolonged after magnetization of the diluted solution with magnetic field intensity of 0.05 T, 0. 11 T, 0.22 T, 0.44T. Especially with magnetic field intensity of 0.11 T, the induction time had even been prolonged to 431min (average). The effect of magnetization on the growth period of NGH has not been found at the experimental condition.
Theoretical Considerations on the Computation of Generalized Time-Periodic Waves
Pauly, Dirk
2011-01-01
We present both, theory and an algorithm for solving time-harmonic wave problems in a general setting. The time-harmonic solutions will be achieved by computing time-periodic solutions of the original wave equations. Thus, an exact controllability technique is proposed to solve the time-dependent wave equations. We discuss a first order Maxwell type system, which will be formulated in the framework of alternating differential forms. This enables us to investigate different kinds of classical wave problems in one fell swoop, such as acoustic, electro-magnetic or elastic wave problems. After a sufficient theory is established, we formulate our exact controllability problem and suggest a least-squares optimization procedure for its solution, which itself is solved in a natural way by a conjugate gradient algorithm operating in the canonical Hilbert space. Therefore, it might be one of the biggest advances of this approach that the proposed conjugate gradient algorithm does not need any preconditioning.
Spacecraft stability and control using new techniques for periodic and time-delayed systems
NAzari, Morad
This dissertation addresses various problems in spacecraft stability and control using specialized theoretical and numerical techniques for time-periodic and time-delayed systems. First, the effects of energy dissipation are considered in the dual-spin spacecraft, where the damper masses in the platform (?) and the rotor (?) cause energy loss in the system. Floquet theory is employed to obtain stability charts for different relative spin rates of the subsystem [special characters omitted] with respect to the subsystem [special characters omitted]. Further, the stability and bifurcation of delayed feedback spin stabilization of a rigid spacecraft is investigated. The spin is stabilized about the principal axis of the intermediate moment of inertia using a simple delayed feedback control law. In particular, linear stability is analyzed via the exponential-polynomial characteristic equations and then the method of multiple scales is used to obtain the normal form of the Hopf bifurcation. Next, the dynamics of a rigid spacecraft with nonlinear delayed multi-actuator feedback control are studied, where a nonlinear feedback controller using an inverse dynamics approach is sought for the controlled system to have the desired linear delayed closed-loop dynamics (CLD). Later, three linear state feedback control strategies based on Chebyshev spectral collocation and the Lyapunov Floquet transformation (LFT) are explored for regulation control of linear periodic time delayed systems. First , a delayed feedback control law with discrete delay is implemented and the stability of the closed-loop response is investigated in the parameter space of available control gains using infinite-dimensional Floquet theory. Second, the delay differential equation (DDE) is discretized into a large set of ordinary differential equations (ODEs) using the Chebyshev spectral continuous time approximation (CSCTA) and delayed feedback with distributed delay is applied. The third strategy involves
Stochastic resonance (SR) of a periodically driven time-delayed linear system with multiplicative white noise and periodically modulated additive white noise is investigated. In the condition of small delay time, an approximate analytical expression of output signal-to-noise ratio (SNR) is obtained. The analytical results indicate that (1) there exists a resonance peak in the curve for SNR versus time delay; (2) the time delay will suspend the SR dramatically for SNR versus other parameters of the system, such as noise intensity, correlation intensity, and signal frequency, once a certain value is reached, the SR phenomenon disappears. (general)
Infrared Time Lags for the Periodic Quasar PG 1302-102
Jun, Hyunsung D.; Stern, Daniel; Graham, Matthew J.; Djorgovski, S. G.; Mainzer, Amy; Cutri, Roc M.; Drake, Andrew J.; Mahabal, Ashish A.
2015-11-01
The optical light curve of the quasar PG 1302-102 at z=0.278 shows a strong, smooth 5.2 year periodic signal, detectable over a period of ∼20 years. Although the interpretation of this phenomenon is still uncertain, the most plausible mechanisms involve a binary system of two supermassive black holes with a subparsec separation. At this close separation, the nuclear black holes in PG 1302-102 will likely merge within ∼ {10}5 years due to gravitational wave emission alone. Here, we report the rest-frame near-infrared time lags for PG 1302-102. Compiling data from WISE and Akari, we confirm that the periodic behavior reported in the optical light curve from Graham et al. is reproduced at infrared wavelengths, with best-fit observed-frame 3.4 and 4.6 μ {{m}} time lags of (2219 ± 153, 2408 ± 148) days for a near face-on orientation of the torus, or (4103 ± 153, 4292 ± 148) days for an inclined system with relativistic Doppler boosting in effect. The periodicity in the infrared light curves and the light-travel time of the accretion disk photons to reach the dust glowing regions support that a source within the accretion disk is responsible for the optical variability of PG 1302-102, echoed at the farther out dusty regions. The implied distance of this dusty, assumed toroidal region is ∼1.5 pc for a near face-on geometry or ∼1.1 pc for the relativistic Doppler-boosted case.
Shit, Anindita; Chattopadhyay, Sudip; Chaudhuri, Jyotipratim Ray
2012-05-01
We explore, in the quantum regime, the stochastic dynamics of a time-periodic, rapidly oscillating potential (having a characteristic frequency of ω) within the framework of a time-dependent system-reservoir Hamiltonian. We invoke the idea of a quantum gauge transformation in light of the standard Floquet theorem in an attempt to construct a Langevin equation (bearing a time-independent effective potential) by employing a systematic perturbative expansion in powers of ω^{-1} using the natural time-scale separation. The time-independent effective potential (corrected to ω^{-2} in leading order) that acts on the slow motion of the driven particle can be employed for trapping. We proceed further to evaluate the rate of escape of the driven particle from the metastable state in the high-temperature limit. We also envisage a resonance phenomena, a true hallmark of the system-reservoir quantization. This development would thus serve as a model template to investigate the trapping mechanism, as well as an appropriate analog to understand the dynamics of a fluctuation-induced escape process from the trap. PMID:23004698
Electromagnetic wave propagation in media whose permittivity varies periodically in time
Cervantes, Juan Carlos; Halevi, Peter
2006-03-01
We have developed a general theory for propagation of plane electromagnetic waves in a medium with permittivity that is varying periodically in time. The Bloch-Floquet theorem dictates that these are a superposition of harmonic modes whose frequencies differ by 2π/T, where T is the period of ɛ(t). For arbitrary periodicity, the dispersion relation φ(t) for the ``Bloch frequency'' is given in terms of the roots of an infinite determinant whose elements depend on the Fourier coefficients of ɛ(t). For small variation of ɛ(t) around an average ɛ0,φ(t) is characterized by regions of the wave vector k that are forbidden for propagation. These are centered at φ and k values that are, respectively, integer multiples of π/T and of πɛ0^1/2 /cT. The widths of the gaps are proportional to the corresponding Fourier coefficients of ɛ(t). In the special case of square-periodic variation of ɛ(t), there is no need to recur to a perturbational calculation, because the dispersion relation can be derived analytically, with no approximations. Again, we find wave vectors gaps whose edges are located at the frequencies φ=0,π/T,2π/T,... .
Practitioners' Perceptions of the Soccer Extra-Time Period: Implications for Future Research
Harper, Liam D.; Fothergill, Melissa; West, Daniel J.; Stevenson, Emma; Russell, Mark
2016-01-01
Qualitative research investigating soccer practitioners’ perceptions can allow researchers to create practical research investigations. The extra-time period of soccer is understudied compared to other areas of soccer research. Using an open-ended online survey containing eleven main and nine sub questions, we gathered the perceptions of extra-time from 46 soccer practitioners, all working for different professional soccer clubs. Questions related to current practices, views on extra-time regulations, and ideas for future research. Using inductive content analysis, the following general dimensions were identified: ‘importance of extra-time’, ‘rule changes’, ‘efficacy of extra-time hydro-nutritional provision’, ‘nutritional timing’, ‘future research directions’, ‘preparatory modulations’ and ‘recovery’. The majority of practitioners (63%) either agreed or strongly agreed that extra-time is an important period for determining success in knockout football match-play. When asked if a fourth substitution should be permitted in extra-time, 67% agreed. The use of hydro-nutritional strategies prior to extra-time was predominately considered important or very important. However; only 41% of practitioners felt that it was the most important time point for the use of nutritional products. A similar number of practitioners account (50%) and do not (50%) account for the potential of extra-time when training and preparing players and 89% of practitioners stated that extra-time influences recovery practices following matches. In the five minute break prior to extra-time, the following practices (in order of priority) were advocated to players: hydration, energy provision, massage, and tactical preparations. Additionally, 87% of practitioners advocate a particular nutritional supplementation strategy prior to extra-time. In order of importance, practitioners see the following as future research areas: nutritional interventions, fatigue responses
Impulsive Periodic Boundary Value Problems for Dynamic Equations on Time Scale
Eric R. Kaufmann
2009-01-01
Full Text Available Let 𝕋 be a periodic time scale with period p such that 0,ti,T=mp∈𝕋, i=1,2,…,n, m∈ℕ, and 0
Markov, Detelin
2012-11-01
This paper presents an easy-to-understand procedure for prediction of indoor air composition time variation in air-tight occupied spaces during the night periods. The mathematical model is based on the assumptions for homogeneity and perfect mixing of the indoor air, the ideal gas model for non-reacting gas mixtures, mass conservation equations for the entire system and for each species, a model for prediction of basal metabolic rate of humans as well as a model for prediction of O2 consumption rate and both CO2 and H2O generation rates by breathing. Time variation of indoor air composition is predicted at constant indoor air temperature for three scenarios based on the analytical solution of the mathematical model. The results achieved reveal both the most probable scenario for indoor air time variation in air-tight occupied spaces as well as the cause for morning tiredness after having a sleep in a modern energy efficient space.
Time-headway distribution for periodic totally asymmetric exclusion process with various updates
Hrabák, P.; Krbálek, M.
2016-03-01
The totally asymmetric exclusion process (TASEP) with periodic boundaries is considered as traffic flow model. The large-L approximation of the stationary state is used for the derivation of the time-headway distribution (an important microscopic characteristic of traffic flow) for the model with generalized update (genTASEP) in both, forward- and backward-sequential representations. The usually used updates, fully-parallel and regular forward- and backward-sequential, are analyzed as special cases of the genTASEP. It is shown that only for those cases, the time-headway distribution is determined by the flow regardless to the density. The qualitative comparison of the results with traffic data demonstrates that the genTASEP with backward order and attractive interaction evinces similar properties of time-headway distribution as the real traffic sample.
Fictitious Domain Technique for the Calculation of Time-Periodic Solutions of Scattering Problem
Ling Rao
2011-01-01
Full Text Available The fictitious domain technique is coupled to the improved time-explicit asymptotic method for calculating time-periodic solution of wave equation. Conventionally, the practical implementation of fictitious domain method relies on finite difference time discretizations schemes and finite element approximation. Our new method applies finite difference approximations in space instead of conventional finite element approximation. We use the Dirac delta function to transport the variational forms of the wave equations to the differential form and then solve it by finite difference schemes. Our method is relatively easier to code and requires fewer computational operations than conventional finite element method. The numerical experiments show that the new method performs as well as the method using conventional finite element approximation.
Timing and periodicity of paraglacial rock-slope failures in the Scottish Highlands
Ballantyne, Colin K.; Stone, John O.
2013-03-01
Many formerly-glaciated mountains exhibit a high density of postglacial rock-slope failures (RSFs) in the form of rockslides, rock avalanches or deep-seated gravitational slope deformations. Such RSFs are often termed 'paraglacial' as they reflect pre-conditioning by glaciation and deglaciation. The temporal pattern of paraglacial RSFs is unknown. We employ 47 cosmogenic isotope exposure ages obtained for 17 catastrophic RSFs in the Scottish Highlands to test models of changes in RSF frequency since deglaciation. Our results show that RSF activity spans almost the entire postglacial period from ~ 17 ka until ~ 1.5 ka, and that the periodicity of sampled postglacial RSFs is statistically indistinguishable from a pattern of uniform periodicity (~ 1 ka- 1). Our data do not conform to proposed models of declining RSF frequency with time elapsed since deglaciation, but suggest that the temporal distribution of postglacial RSFs is best described by a combination of rapid response (enhanced RSF frequency during or immediately after deglaciation) followed by approximately constant periodicity. Our findings are consistent with near-surface fracturing of rock when glacially-induced confining stresses are removed, causing some failures during or immediately after deglaciation and reducing other slopes to critical conditional stability so that failure is triggered by progressive rock-mass weakening or by transient triggering mechanisms. Neither permafrost degradation (thaw of ice in joints) nor seismic activity offers a general explanation for triggering Scottish RSFs, but could be contributory in some cases. The quasi-constant periodicity inferred for Holocene RSFs implies that the probability of RSFs in this seismically-quiescent intraplate area has not changed in the past ~ 10 ka, and that further (though infrequent) catastrophic RSFs are likely to occur in the future.
van Baalen, Guillaume; Wittwer, Peter
2011-01-01
We construct solutions for the Navier–Stokes equations in three dimensions with a time periodic force which is of compact support in a frame that moves at constant speed. These solutions are related to solutions of the problem of a body which moves within an incompressible fluid at constant speed and rotates around an axis which is aligned with the motion. In contrast to other authors who analyze stationary solutions in a frame of reference attached to the body, the analysis for the present p...
Behaviour of a thermodynamic model system under time-dependent periodic boundary conditions
Berry, R.S. (Chicago Univ., IL (USA). Dept. of Chemistry); D' Isep, F.; Sertorio, L. (Turin Univ. (Italy). Ist. di Fisica; Istituto Nazionale di Fisica Nucleare, Turin (Italy))
A finite domain D/sub 2/ is enveloped by a finite domain D/sub 1/. The domain D/sub 1/, in turn, is in contact with two thermal baths with time-dependent periodic temperatures Tsub(s)(t) and Tsub(e)(t). We search for the best way to make T/sub 2/, the temperature field belonging to D/sub 2/, as close as possible to a predetermined constant. This can be obtained with the insertion of controlled energy sources or sinks. We study the formal approach with zero energy expenditure and the maximization problem which is implied.
Adesanya, S. O.; Oluwadare, E. O.; Falade, J. A.; Makinde, O. D.
2015-12-01
In this paper, the free convective flow of magnetohydrodynamic fluid through a channel with time periodic boundary condition is investigated by taking the effects of Joule dissipation into consideration. Based on simplifying assumptions, the coupled governing equations are reduced to a set of nonlinear boundary valued problem. Approximate solutions are obtained by using semi-analytical Adomian decomposition method. The effect of pertinent parameters on the fluid velocity, temperature distribution, Nusselt number and skin friction are presented graphically and discussed. The result of the computation shows that an increase in the magnetic field intensity has significant influence on the fluid flow.
Yu, Kyung-Hun; Suk, Min-Hwa; Kang, Shin-Woo; Shin, Yun-A
2014-01-01
The purpose of this study was to investigate the effect of combined linear and nonlinear periodic training on physical fitness and competition times in finswimmers. The linear resistance training model (6 days/week) and nonlinear underwater training (4 days/week) were applied to 12 finswimmers (age, 16.08± 1.44 yr; career, 3.78± 1.90 yr) for 12 weeks. Body composition measures included weight, body mass index (BMI), percent fat, and fat-free mass. Physical fitness measures included trunk flex...
Summary of the CDFE nuclear data activity for 2011 - 2012 period of time, Progress report
This report contains the short review of the main fields of nuclear data activity of the Centre for Photonuclear Experiments Data (Centr Dannykh Fotoyadernykh Eksperimentov - CDFE) of Skobeltsyn Institute of Nuclear Physics of Lomonosov Moscow State University and main results obtained. All works were carried out in close co-operation with the Nuclear Science Section in the frame of the IAEA Nuclear Reaction Data Centres Network for the period of time from the IAEA Technical Meeting on the International Network of Nuclear Reaction Data Centers' (23 - 24 May 2011, IAEA, Vienna, Austria) till the spring of 2012. (author)
The Cluster Science Archive: from Time Period to Physics Based Search
Masson, A.; Escoubet, C. P.; Laakso, H. E.; Perry, C. H.
2015-12-01
Since 2000, the Cluster spacecraft relay the most detailed information on how the solar wind affects our geospace in three dimensions. Science output from Cluster is a leap forward in our knowledge of space plasma physics: the science behind space weather. It has been key in improving the modeling of the magnetosphere and understanding its various physical processes. Cluster data have enabled the publication of more than 2000 refereed papers and counting. This substantial scientific return is often attributed to the online availability of the Cluster data archive, now called the Cluster Science Archive (CSA). It is being developed by the ESAC Science Data Center (ESDC) team and maintained alongside other science ESA archives at ESAC (ESA Space Astronomy Center, Madrid, Spain). CSA is a public archive, which contains the entire set of Cluster high-resolution data, and other related products in a standard format and with a complete set of metadata. Since May 2015, it also contains data from the CNSA/ESA Double Star mission (2003-2008), a mission operated in conjunction with Cluster. The total amount of data format now exceeds 100 TB. Accessing CSA requires to be registered to enable user profiles and CSA accounts more than 1,500 users. CSA provides unique tools for visualizing its data including - on-demand particle distribution functions visualization - fast data browsing with more than 15TB of pre-generated plots - inventory plots It also offers command line capabilities (e.g. data access via Matlab or IDL softwares, data streaming). Despite its reliability, users can only request data for a specific time period while scientists often focus on specific regions or data signatures. For these reasons, a data-mining tool is being developed to do just that. It offers an interface to select data based not only on a time period but on various criteria including: key physical parameters, regions of space and spacecraft constellation geometry. The output of this tool is a
Exact control of parity-time symmetry in periodically modulated nonlinear optical couplers
Yang, Baiyuan; Hu, QiangLin; Yu, XiaoGuang
2016-01-01
We propose a mechanism for realization of exact control of parity-time (PT) symmetry by using a periodically modulated nonlinear optical coupler with balanced gain and loss. It is shown that for certain appropriately chosen values of the modulation parameters, we can construct a family of exact analytical solutions for the two-mode equations describing the dynamics of such nonlinear couplers. These exact solutions give explicit examples that allow us to precisely manipulate the system from nonlinearity-induced symmetry breaking to PT symmetry, thus providing an analytical approach to the all-optical signal control in nonlinear PT-symmetric structures.
Dobson, Matthew
2014-11-01
This work presents a generalization of the Kraynik-Reinelt (KR) boundary conditions for nonequilibrium molecular dynamics simulations. In the simulation of steady, homogeneous flows with periodic boundary conditions, the simulation box deforms with the flow, and it is possible for image particles to become arbitrarily close, causing a breakdown in the simulation. The KR boundary conditions avoid this problem for planar elongational flow and general planar mixed flow [T. A. Hunt, S. Bernardi, and B. D. Todd, J. Chem. Phys. 133, 154116 (2010)] through careful choice of the initial simulation box and by periodically remapping the simulation box in a way that conserves image locations. In this work, the ideas are extended to a large class of three-dimensional flows by using multiple remappings for the simulation box. The simulation box geometry is no longer time-periodic (which was shown to be impossible for uniaxial and biaxial stretching flows in the original work by Kraynik and Reinelt [Int. J. Multiphase Flow 18, 1045 (1992)]. The presented algorithm applies to all flows with nondefective flow matrices, and in particular, to uniaxial and biaxial flows.
The Varying Light Curve and Timings of the Ultra-short Period Contact Binary KIC 9532219
Lee, Jae Woo; Koo, Jae-Rim; Park, Jang-Ho
2016-01-01
KIC 9532219 is a W UMa-type eclipsing binary with an orbital period of 0.1981549 d that is below the short-period limit ($\\sim$0.22 d) of the period distribution for contact binaries. The {\\it Kepler} light curve of the system exhibits striking light changes in both eclipse depths and light maxima. Applying third-body and spot effects, the light-curve synthesis indicates that the eclipsing pair is currently in a marginal contact stage with a mass ratio of $q$=1.20, an orbital inclination of $i$=66.0 deg, a temperature difference of $\\Delta$ ($T_{1}$--$T_{2}$)=172 K, and a third light of $l_3$=75.9 \\%. To understand the light variations with time, we divided up the light curve into 312 segments and separately analyzed them. The results reveal that variation of eclipse depth is primarily caused by changing amounts of contamination due to the nearby star KIC9532228 between the {\\it Kepler} Quarters and that the variable O'Connell effect originates from the starspot activity on the less massive primary component....
Time-dependent Mott transition in the periodic Anderson model with nonlocal hybridization
Hofmann, Felix; Potthoff, Michael
2016-08-01
The time-dependent Mott transition in a periodic Anderson model with off-site, nearest-neighbor hybridization is studied within the framework of nonequilibrium self-energy functional theory. Using the two-site dynamical-impurity approximation, we compute the real-time dynamics of the optimal variational parameter and of different observables initiated by sudden quenches of the Hubbard-U and identify the critical interaction. The time-dependent transition is orbital selective, i.e., in the final state, reached in the long-time limit after the quench to the critical interaction, the Mott gap opens in the spectral function of the localized orbitals only. We discuss the dependence of the critical interaction and of the final-state effective temperature on the hybridization strength and point out the various similarities between the nonequilibrium and the equilibrium Mott transition. It is shown that these can also be smoothly connected to each other by increasing the duration of a U-ramp from a sudden quench to a quasi-static process. The physics found for the model with off-site hybridization is compared with the dynamical Mott transition in the single-orbital Hubbard model and with the dynamical crossover found for the real-time dynamics of the conventional Anderson lattice with on-site hybridization.
Two-dimensional, time dependent simulation of the planetary boundary layer over a 48-hour period
This report presents results of a two-dimensional time-dependent simulation of the planetary boundary layer for a 48-hour period. These calculations are a continuation and expansion of one-dimensional simulations of the planetary boundary layer as described previously. The time-dependent evolution of a weather situation was simulated. It could be demonstrated that the main features of local ventilation systems can be simulated correctly. Two case studies are presented to show qualitatively, how local circulation systems can be influenced. One case assumes introduction of a hypothetical city, the other case uses arbitrarily introduced coverage of the sky as a pertubrbation. The problems connected with the verification of two-dimensional simulations using experimental data are discussed. Furthermore, proposals for a methodology to solve problems of model verification are discussed. (Auth.)
Charge pumping in monolayer graphene driven by a series of time-periodic potentials
Wu, Zhenhua, E-mail: zhwu@semi.ac.cn [SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, 100083, Beijing (China); CAE Team, Semiconductor R and D Center, Samsung Electronics Co. Ltd., Gyeonggi-Do (Korea, Republic of); Li, J. [Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005 (China); Chan, K.S., E-mail: apkschan@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)
2012-02-27
We applied the Floquet scattering-matrix formalism to studying the electronic transport properties in a mesoscopic Dirac system. Using the method, we investigate theoretically quantum pumping driven by a series of time-periodic potentials in graphene monolayer both in the adiabatic and non-adiabatic regimes. Our numerical results demonstrate that adding harmonic modulated potentials can break the time reversal symmetry when no voltage bias is applied to the graphene monolayer. Thus, when the system is pumped with proper dynamic parameters, these scatterers can produce a nonzero dc pumped current. We also find that the transmission is anisotropic as the incident angle is changed. -- Highlights: ► We applied the Floquet scattering-matrix formalism to Dirac-electron system. ► We investigated the quantum pumping both in adiabatic and non-adiabatic regimes. ► We evaluated the pumped dc current induced by harmonic modulated potentials.
Estimating inter-event time distributions from finite observation periods in communication networks
Kivelä, Mikko
2014-01-01
A diverse variety of processes --- including recurrent disease episodes, neuron firing, and communication patterns among humans --- can be described using inter-event time (IET) distributions. Many such processes are ongoing, although event sequences are only available during a finite observation window. Because the observation time window is more likely to begin or end during long IETs than during short ones, the analysis of such data is susceptible to a bias induced by the finite observation period. In this paper, we illustrate how this length bias is born and how it can be corrected. To do this, we model event sequences using stationary renewal processes, and we formulate simple heuristics for determining the severity of the bias. To illustrate our results, we focus on the example of empirical communication networks, which are temporal networks that are constructed from communication events. The IET distributions of such systems guide efforts to build models of human behavior, and the variance of IETs is v...
Mixer-Duplexer-Antenna Leaky-Wave System Based on Periodic Space-Time Modulation
Taravati, Sajjad
2016-01-01
We present a mixer-duplexer-antenna leaky-wave system based on periodic space-time modulation. This system operates as a full transceiver, where the upconversion and downconversion mixing operations are accomplished via space-time transitions, the duplexing operation is induced by the nonreciprocal nature of the structure, and the radiation operation is provided by the leaky-wave nature of the wave. A rigorous electromagnetic solution is derived for the dispersion relation and field distributions. The system is implemented in the form of a spatio-temporally modulated microstrip leaky-wave structure incorporating an array of sub-wavelengthly spaced varactors modulated by a harmonic wave. In addition to the overall mixer-duplexer-antenna operation, frequency beam scanning at fixed input frequency is demonstrated as one of the interesting features of the system. A prototype is realized and demonstrated by full-wave and experimental results.
Matheus Melo Pithon
2010-06-01
Full Text Available As new orthodontic resin adhesives continue to be marketed, rapid and sensitive tests for examining their toxic effects at the ' cell and tissue level ' are needed because patient safety has been identifi ed as a legal concept. The objective of the present study was to evaluate the cytotoxicity and degree of monomer conversion of orthodontic adhesives over different time periods. Seven adhesives: Transbond® XT, Transbond® Color Change, Quick Cure, EagleBond, Orthobond®, Fill Mágic® and Biofix® were evaluated for their cytotoxicity in L929 fibroblastic cells and for their degree of monomer conversion over different time periods. Three control groups were also analysed: Positive control (C+, consisting of Tween 80 cell detergent; Negative control (C-, consisting of PBS; and cell control (CC, consisting of cells exposed to any material. The dye-uptake technique that involves the absorption of a neutral red dye in viable cells was used for the cytotoxicity evaluation and the degree of conversion was evaluated using spectroscopy with infrared. The results showed the cytotoxicity of the adhesives at 24, 48, 72 and 168 hours. At these times, the viability values presented for these materials were statistically different from the groups CC and C- (p 0.05. In the monomer conversions there was a percentage increase of monomer conversion from 24 to 72 hours. A direct correlation could be observed between cytotoxicity and monomer conversions. From this work it can be concluded that all adhesives evaluated are cytotoxic at the times of 24, 48 and 72 hours. Monomers continued conversion even after photopolymerization had stopped.
THE INFLUENCE OF IDEAS OF THE NEW TIME PERIOD ON THE FORMATION OF THE GENDER PSYCHOLOGY
Veronika Olegovna Mokhova
2014-08-01
Full Text Available This Article deals with the history of gender psychology in Russia, which reflects the ideas of national publications within the New Time period (1640-1918 in a modern gender science. Since 1750 the first works on the topic of the place of a man and a woman in society started to appear in Russia, related to their possibilities and capabilities. The Article contains the analysis of the dynamics in the subject range of papers related to sex differences, issued in Russia from the 18th till the early 20th century by using method of qualitative content analysis. The Article contains the material of the two libraries: the Russian National Library and the Russian State Library from 1700 to 1918, dealing with problems of sexes and a social position of men and women. Conclusions at the end of this research are the essence of the ideas, which were critical for the emergence and development of the gender psychology.Purpose: the main goal of this Article is to present the analysis of ideas of the New Time period which are significant for modern gender psychology.Methodology: qualitative content analysis.Results: the analysis of the dynamics in the subject range of papers related to sex differences, published in Russia from the 18th till the early 20th century.Practical implications: the history of gender psychology.
Models for maintenance optimization: a study for repairable systems and finite time periods
The problem of selecting a suitable maintenance policy for repairable systems and for a finite time period is presented. Since the late seventies, examples of models assessing corrective and preventive maintenance policies over an equipment life cycle exist in the literature. However, there are not too many contributions regarding real implementation of these models in the industry, considering realistic timeframes and for repairable systems. Modeling this problem requires normally the representation of different corrective and/or preventive actions that could take place at different moments, driving the equipment to different states with different hazard rates. An approach to pattern the system under finite periods of time has been the utilization of semi-Markovian probabilistic models, allowing later a maintenance policy optimization using dynamic programming. These models are very flexible to represent a given system, but they are also complex and therefore very difficult to handle when the number of the system possible states increases. This paper explores the trade-off between flexibility and complexity of these models, and presents a comparison in terms of model data requirements versus potential benefits obtained with the model
The noise-time of response compromise in d.c. period meters. A new type of circuit (1961)
The report compares the characteristics of three period meter circuits: - a linear circuit - a circuit which is non-linear according to the nuclear reactor period - a circuit which is non-linear according to the period and the power of the reactor. This last type of reactor has a fast time of response if the power is high or if the period is short, and it has a slow time of response when the power is low and the period long; this system makes it possible to maintain the noise at an acceptable level under all normal working conditions of the reactor. (author)
Long-time asymptotics of the periodic Toda lattice under short-range perturbations
Kamvissis, Spyridon; Teschl, Gerald
2012-07-01
We compute the long-time asymptotics of periodic (and slightly more generally of algebro-geometric finite-gap) solutions of the doubly infinite Toda lattice under a short-range perturbation. In particular, we prove that the perturbed lattice asymptotically approaches a modulated lattice. More precisely, let g be the genus of the hyperelliptic curve associated with the unperturbed solution. We show that, apart from the phenomenon of solitons travelling in a quasi-periodic background, the n/t-pane contains g + 2 areas where the perturbed solution is close to a finite-gap solution on the same isospectral torus. In between there are g + 1 regions where the perturbed solution is asymptotically close to a modulated lattice which undergoes a continuous phase transition (in the Jacobian variety) and which interpolates between these isospectral solutions. In the special case of the free lattice (g = 0), the isospectral torus consists of just one point and we recover the known result. Both the solutions in the isospectral torus and the phase transition are explicitly characterized in terms of Abelian integrals on the underlying hyperelliptic curve. Our method relies on the equivalence of the inverse spectral problem to a vector Riemann-Hilbert problem defined on the hyperelliptic curve and generalizes the so-called nonlinear stationary phase/steepest descent method for Riemann-Hilbert problem deformations to Riemann surfaces.
Padovani, Tullia; Koenig, Thomas; Eckstein, Doris; Perrig, Walter J
2013-07-01
Memory formation is commonly thought to rely on brain activity following an event. Yet, recent research has shown that even brain activity previous to an event can predict later recollection (subsequent memory effect, SME). In order to investigate the attentional sources of the SME, event-related potentials (ERPs) elicited by task cues preceding target words were recorded in a switched task paradigm that was followed by a surprise recognition test. Stay trials, that is, those with the same task as the previous trial, were contrasted with switch trials, which included a task switch compared to the previous trial. The underlying assumption was that sustained attention would be dominant in stay trials and that transient attentional reconfiguration processes would be dominant in switch trials. To determine the SME, local and global statistics of scalp electric fields were used to identify differences between subsequently remembered and forgotten items. Results showed that the SME in stay trials occurred in a time window from 2 to 1 sec before target onset, whereas the SME in switch trials occurred subsequently, in a time window from 1 to 0 sec before target onset. Both SMEs showed a frontal negativity resembling the topography of previously reported effects, which suggests that sustained and transient attentional processes contribute to the prestimulus SME in consecutive time periods. PMID:24381815
A first principles TDDFT framework for spin and time-resolved ARPES in periodic systems
De Giovannini, Umberto; Rubio, Angel
2016-01-01
We present a novel theoretical approach to simulate spin, time and angular-resolved photoelectron spectroscopy (ARPES) from first principles that is applicable to surfaces, thin films, few layer systems, and low-dimensional nanostructures. The method is based on a general formulation in the framework of time-dependent density functional theory (TDDFT) to describe the real time-evolution of electrons escaping from a surface under the effect of any external (arbitrary) laser field. By extending the so called t-SURFF method to periodic systems one can calculate the final photoelectron spectrum by collecting the flux of the ionization current trough an analysing surface. The resulting approach, that we named t-SURFFP, allows to describe a wide range of irradiation conditions without any assumption on the dynamics of the ionization process allowing for pump-probe simulations on an equal footing. To illustrate the wide scope of applicability of the method we present applications to graphene, mono- and bi-layer WSe$...
MULTI BAND INSAR ANALYSIS OF SUBSIDENCE DEVELOPMENT BASED ON THE LONG PERIOD TIME SERIES
F. C. Çomut
2015-12-01
Full Text Available The SAR Interferometry (InSAR application has shown great potential in monitoring of land terrain changes and in detection of land deformations such as subsidence. Longer time analysis can lead to understand longer trends and changes. Using different bands of SAR satellite (C- from ERS 1-2 and Envisat, L- from ALOS over the study area, we achieve knowledge of movements in long-term and evaluation of its dynamic changes within observed period of time. Results from InSAR processing fit with the position changes in vertical direction based on GPS network established over the basin as an effective geodetic network. Time series (StaMPS PS+SB of several points over Çumra County in eastern part of Konya City show a general trend of the deformation that is expected to be approximately between -13 to -17 mm/year. Northern part of Karaman is affected by faster subsidence, borders of the subsidence trough were identified from Envisat. Presenting InSAR results together with GIS information about locations and time of occurrence of sudden subsidence, urban/industrial growth in time and climate changes helps in better understanding of the situation. This way, the impact of natural and man-made changes will be shown for urban planning thanks to InSAR and GIS comparisons with hydrogeological modeling. In this study we present results of differential and multitemporal InSAR series using different bands and GIS conjunction associated with seasonal and temporal groundwater level changes in Konya Closed Basin.
Multi Band Insar Analysis of Subsidence Development Based on the Long Period Time Series
Çomut, F. C.; Ustun, A.; Lazecky, M.; Aref, M. M.
2015-12-01
The SAR Interferometry (InSAR) application has shown great potential in monitoring of land terrain changes and in detection of land deformations such as subsidence. Longer time analysis can lead to understand longer trends and changes. Using different bands of SAR satellite (C- from ERS 1-2 and Envisat, L- from ALOS) over the study area, we achieve knowledge of movements in long-term and evaluation of its dynamic changes within observed period of time. Results from InSAR processing fit with the position changes in vertical direction based on GPS network established over the basin as an effective geodetic network. Time series (StaMPS PS+SB) of several points over Çumra County in eastern part of Konya City show a general trend of the deformation that is expected to be approximately between -13 to -17 mm/year. Northern part of Karaman is affected by faster subsidence, borders of the subsidence trough were identified from Envisat. Presenting InSAR results together with GIS information about locations and time of occurrence of sudden subsidence, urban/industrial growth in time and climate changes helps in better understanding of the situation. This way, the impact of natural and man-made changes will be shown for urban planning thanks to InSAR and GIS comparisons with hydrogeological modeling. In this study we present results of differential and multitemporal InSAR series using different bands and GIS conjunction associated with seasonal and temporal groundwater level changes in Konya Closed Basin.
Reference value of long-time exercise test in the diagnosis of primary periodic paralysis
Ding Zeyu; Liu Mingsheng; Cui Liying
2014-01-01
Background The long-time exercise test (ET) is used to diagnose the primary periodic paralyses (PPs).However the reference values of ET are many and various.This study aimed to investigate the reference value of long-time ET in the diagnosis of PPs.Methods We recruited 108 healthy subjects,68 patients with PPs,and 72 patients with other diseases for the study.The procedure of ET was made on the basis of the McManis' method.Electrical responses were recorded from right abductor digiti minimi (ADM) muscle when stimulation of the ulnar nerve at the wrist.After the compound muscle action potential (CMAP) was monitored,subjects were then asked to contract the muscle as strongly as possible for 5 minutes.CMAPs were recorded for 2 seconds immediately after cessation of exercise,then every 5 minutes for 10 minutes,and finally every 10 minutes for 50 minutes.In general,the CMAP amplitudes will fall below the pre-exercise levels in an hour.The largest decrease was calculated and used as results of ET.Results The CMAP amplitude decreases had no significant differences between groups when the healthy adults were grouped according to age,gender,height,weight and test time.Decreases in PPs patients (57.76％) were significantly more than in healthy subjects (15.21％) and other disease patients (18.10％,P ＜0.001).Receiver operating characteristic (ROC) curve analysis showed that the best threshold is 35.50％.Conclusions In the long-time exercise test,threshold of 35.50％ for the CMAP amplitude decrease was identified for abnormal.The result is not influenced by age,gender,height,weight,and test time.About 7.4％ of healthy subjects were abnormal in ET.
Network news coverage of obesity in two time periods: an analysis of issues, sources, and frames.
Gearhart, Sherice; Craig, Clay; Steed, Chaille
2012-01-01
Obesity is an epidemic plaguing American society. The current study adds to a growing body of framing research as it examines the portrayal of obesity on television network news in two 5-year time periods, 1995-1999 and 2005-2009. Through content analysis of TV news transcripts from three networks (ABC, NBC, and CBS), this study analyzed episodic-thematic frames, issues, and sources. Results revealed the amount of obesity-related news coverage increased along with thematically framed stories. The use of politicians, affected others, supporters, and others as sources increased, but experts and those struggling with obesity remained primary sources. Changes in the proportion of issues discussed revealed significant decreases in the discussion of genetic causes and personal stories. Results reflect the societal impact of obesity and indicate the ways in which obesity is perceived by the public through network news. Findings provide insight for media advocacy opportunities and contribute to research on framing and obesity. PMID:22236324
Adesanya, S.O., E-mail: adesanyas@run.edu.ng [Department of Mathematical Sciences, College of Natural Sciences, Redeemer’s University (Nigeria); Oluwadare, E.O. [Department of Mathematical Sciences, College of Natural Sciences, Redeemer’s University (Nigeria); Falade, J.A., E-mail: faladej@run.edu.ng [Department of Physical Sciences, College of Natural Sciences, Redeemer’s University (Nigeria); Makinde, O.D., E-mail: makinded@gmail.com [Faculty of Military Science, Stellenbosch University, Private Bag X2, Saldanha 7395 (South Africa)
2015-12-15
In this paper, the free convective flow of magnetohydrodynamic fluid through a channel with time periodic boundary condition is investigated by taking the effects of Joule dissipation into consideration. Based on simplifying assumptions, the coupled governing equations are reduced to a set of nonlinear boundary valued problem. Approximate solutions are obtained by using semi-analytical Adomian decomposition method. The effect of pertinent parameters on the fluid velocity, temperature distribution, Nusselt number and skin friction are presented graphically and discussed. The result of the computation shows that an increase in the magnetic field intensity has significant influence on the fluid flow. - Highlights: • The influence of magnetic field on the free convective fluid flow is considered. • The coupled equations are solved by using Adomian decomposition method. • The Adomian series solution agreed with previously obtained result. • Magnetic field decreases the velocity maximum but enhances temperature field.
Multiple periodic solutions for a discrete time model of plankton allelopathy
Zhang Jianbao; Fang Hui
2006-01-01
We study a discrete time model of the growth of two species of plankton with competitive and allelopathic effects on each other N1(k+1) = N1(k)exp{r1(k)-a11(k)N1(k)-a12(k)N2(k)-b1(k)N1(k)N2(k)}, N2(k+1) = N2(k)exp{r2(k)-a21(k)N2(k)-b2(k)N1(k)N1(k)N2(k)}. A set of sufficient conditions is obtained for the existence of multiple positive periodic solutions for this model. The approach is based on Mawhin's continuation theorem of coincidence degree theory as well as some a priori estimates. Some...
Efficiency, Power and Period of a model quantum heat engine working in a finite time
Bekele, Mulugeta; Dima, Tolasa A.; Alemye, Mekuannent; Chegeno, Warga
We take a spin-half quantum particle undergoing Carnot type cyclic process in a finite time assisted by two heat reservoirs and an external magnetic field. We find that the power of the heat engine is maximum at a particular period of the cyclic process and efficiency at the maximum power is at least half of the Carnot efficiency. We further apply the Omega-criterion for a figure of merit representing a compromise between useful power and lost power determining the corresponding efficiency for the optimization criterion to be at least three fourth of the Carnot efficiency. The authers are thankful to the International Science programme, IPS, Uppsala, Sweden for their support to our research lab.
Another way of deriving the ring current decay time during disturbed periods
J. R. Manzano
1995-06-01
Full Text Available Coupling parameter, E, and the total energy dissipated by the magnetosphere, UT, are determined for six disturbed periods, following three known criteria for UT computation. It is observed that UT exceeds E for Dst < -90 nT, for alI models. Differences between models reside on the estimated valnes for the particles' life time il1 the equatorial ring current. The values of TR, used in the models, are small during the main phase of the di."turbance, in disagreement with the charge exchange life time of the majority species, H+ and O'-. Based on this conclusion, a different criterion to calculate TR is proposed, differentiating the different stages of the perturbation. TR is calculated, for the main phase of the storm, from the rate of energy deposition estimation, Q, in the ring current. For Dst recovery phase, the vallles are obtained from a ring current decay law computation. The UTvu calculated, physically more coherent with the processes occurring during the event, is now smaller than expected. In this sense, it is understood that the power generated by the solar wind-magnetosphere dy- namo, should also be distributed in the inner magnetosphere, auroral zones and equatorial ring current, as in the outer magnetosphere, plasmoids in the tail shot in antisolar direction. A further adjustment of E, with the Chapman-Ferraro distance, 10' variable, has been made. Although the reslllts, improve the estimation of E, they are sti!l smaller than UT, except UTNU, for some disturbed periods. This result indicates the uncertainty in the computation of the input energy, by using the many expressions proposed in the literature, which are always presented as laws proportional to a given group of parameters, with an unknown factor of proportionality, which deserves more detailed physical analysis.
Estimating interevent time distributions from finite observation periods in communication networks
Kivelä, Mikko; Porter, Mason A.
2015-11-01
A diverse variety of processes—including recurrent disease episodes, neuron firing, and communication patterns among humans—can be described using interevent time (IET) distributions. Many such processes are ongoing, although event sequences are only available during a finite observation window. Because the observation time window is more likely to begin or end during long IETs than during short ones, the analysis of such data is susceptible to a bias induced by the finite observation period. In this paper, we illustrate how this length bias is born and how it can be corrected without assuming any particular shape for the IET distribution. To do this, we model event sequences using stationary renewal processes, and we formulate simple heuristics for determining the severity of the bias. To illustrate our results, we focus on the example of empirical communication networks, which are temporal networks that are constructed from communication events. The IET distributions of such systems guide efforts to build models of human behavior, and the variance of IETs is very important for estimating the spreading rate of information in networks of temporal interactions. We analyze several well-known data sets from the literature, and we find that the resulting bias can lead to systematic underestimates of the variance in the IET distributions and that correcting for the bias can lead to qualitatively different results for the tails of the IET distributions.
Yu. I. Shapovalov
2015-03-01
Full Text Available Introduction. The architecture of MAOPCs functions system and examples of its application for solving the tasks of multivariate analysis of linear periodically time-variable (LPTV circuits based on the frequency symbolic method are considered in this paper. The method is based on approximation of transfer functions of LPTV circuits in the form of trigonometric polynomials of the Fourier. The MAOPCs functions system is implemented in the environment of MATLAB. Architecture and functions of the system MAOPCs. The system consists of 17 functions that are implemented in the environment of MATLAB. Each function has arguments and global variables and carries out over them identified transformation. Functions and global variables form the input data program for research LPTV circuit and should be defined (set at the time of calling the function. Conclusions. The MAOPCs functions system enables to investigate LPTV circuits, setting in program input data the algorithms for their research and to use a strong symbolic apparatus and other standard functions of the package MATLAB in full, without understanding the deep of mathematical apparatus of implemented methods.
Photodeposition of metallic nanostructures onto ferroelectric surfaces, which have been chemically patterned using a proton exchange process, has recently been demonstrated. By varying the molar concentration of the AgNO3 solution and the illumination time, one can determine the initial nucleation sites, control the rate of nucleation and the height of silver nanostructures formed, and study the mechanisms by which these processes occurs. The nanoparticles are found to deposit preferentially in the boundary between ferroelectric and proton exchanged regions, in an area proton exchanged via lateral diffusion under the masking layer used for chemical patterning, consistent with our previous results. Using a short illumination time (3 min), we are able to determine that the initial nucleation of the silver nanostructure, having a width of 0.17 ± 0.02 μm and a height of 1.61 ± 0.98 nm, occurs near the edge of the reactive ion etched area within this lateral diffusion region. Over longer illumination times (15 min), we find that the silver deposition has spread to a width of 1.29 ± 0.06 μm, extending across the entire lateral diffusion region. We report that at a high molar concentration of AgNO3 (10−2 M), the amount of silver deposition for 5 min UV illumination is greater (2.88 ± 0.58 nm) compared to that at low (10−4 M) concentrations (0.78 ± 0.35 nm), however, this is not the case for longer time periods. With increasing illumination time (15 min), experiments at 10−4 M had greater overall deposition, 6.90 ± 1.52 nm, compared to 4.50 ± 0.76 nm at 10−2 M. For longer exposure times (30 min) at 10−2 M, the nanostructure height is 4.72 ± 0.59 nm, suggesting a saturation in the nanostructure height. The results are discussed in terms of the electric double layer that forms at the crystal surface. There is an order of magnitude difference between the Debye lengths for 10−2 and 10−4 M solutions, i.e., 3.04 vs. 30.40 nm, which suggests the Debye
Jiang, Ping; Zeng, Zhigang; Chen, Jiejie
2015-08-01
In this paper, we study the existence and global exponential stability of almost periodic solution for memristor-based neural networks with leakage, time-varying and distributed delays. Using a new Lyapunov function method, we prove that this delayed neural network has a unique almost periodic solution, which is globally exponentially stable. Moreover, the obtained conclusion on the almost periodic solution is applied to prove the existence and stability of periodic solution (or equilibrium point) for this delayed neural network with periodic coefficients (or constant coefficients). PMID:25978771
Edward S Ruthazer
2010-06-01
Full Text Available The retinotectal projection in Xenopus laevis has been shown to exhibit correlation-based refinement of both anatomical and functional connectivity during development. Spike timing-dependent plasticity (STDP is an appealing experimental model for correlation-based synaptic plasticity because, in contrast to plasticity induction paradigms using tetanic stimulation or sustained postsynaptic depolarization, its induction protocol more closely resembles natural physiological activity. In Xenopus tadpoles, where anatomical remodeling has been reported throughout much of the life of the animal, in vivo retinotectal STDP has only been examined under a limited set of experimental conditions. Using perforated patch recordings of retina-evoked EPSCs in tectal neurons, we confirmed that repeatedly driving a retinotectal EPSP 5-10 ms prior to inducing an action potential in the postsynaptic cell, reliably produced timing-dependent long-term potentiation (t-LTP of the retinotectal synapse in young wild type tadpoles (stages 41-44. At these stages, retinotectal timing-dependent long-term depression (t-LTD also could be induced by evoking an EPSP to arrive 5-10 ms after an action potential in the tectal cell. However, retinotectal STDP using this standard protocol was limited to a developmental sensitive period, as we were unable to induce t-LTP or t-LTD after stage 44. Surprisingly, this STDP protocol also failed to induce reliable STDP in albino tadpoles at the early ages when it was effective in wild type pigmented animals. Nonetheless, low-frequency flashes to the eye produced a robust NMDA receptor-dependent retinotectal LTD in stage 47 albino tadpoles, demonstrating that the retinotectal synapse can nonetheless be modified in these animals using different plasticity paradigms.
Time-Based Measurement of Personal Mite Allergen Bioaerosol Exposure over 24 Hour Periods.
Tovey, Euan R; Liu-Brennan, Damien; Garden, Frances L; Oliver, Brian G; Perzanowski, Matthew S; Marks, Guy B
2016-01-01
Allergic diseases such as asthma and rhinitis are common in many countries. Globally the most common allergen associated with symptoms is produced by house dust mites. Although the bed has often been cited as the main site of exposure to mite allergens, surprisingly this has not yet been directly established by measurement due to a lack of suitable methods. Here we report on the development of novel methods to determine the pattern of personal exposure to mite allergen bioaerosols over 24-hour periods and applied this in a small field study using 10 normal adults. Air was sampled using a miniature time-based air-sampler of in-house design located close to the breathing zone of the participants, co-located with a miniature time-lapse camera. Airborne particles, drawn into the sampler at 2L/min via a narrow slot, were impacted onto the peripheral surface of a disk mounted on the hour-hand of either a 12 or 24 hour clock motor. The impaction surface was either an electret cloth, or an adhesive film; both novel for these purposes. Following a review of the time-lapse images, disks were post-hoc cut into subsamples corresponding to eight predetermined categories of indoor or outdoor location, extracted and analysed for mite allergen Der p 1 by an amplified ELISA. Allergen was detected in 57.2% of the total of 353 subsamples collected during 20 days of sampling. Exposure patterns varied over time. Higher concentrations of airborne mite allergen were typically measured in samples collected from domestic locations in the day and evening. Indoor domestic Der p 1 exposures accounted for 59.5% of total exposure, whereas total in-bed-asleep exposure, which varied 80 fold between individuals, accounted overall for 9.85% of total exposure, suggesting beds are not often the main site of exposure. This study establishes the feasibility of novel methods for determining the time-geography of personal exposure to many bioaerosols and identifies new areas for future technical
Categorization of ber varieties in relation to blooming period, fruit setting and harvesting time
Thirty four local Ber varieties were evaluated at Horticultural Research Institute AARI, Faisalabad, Horticultural Research Station Bahawalpur (Punjab) and Jujube Research Station, Tandojam (Sindh). Traits viz. total period of blooming (dates), peak period of blooming (dates), total period of fruit set (dates), peak period of fruit set (dates), total period of fruit harvest (dates), peak period of fruit harvest (dates), total flowering days, peak flowering days, total fruit setting days, peak fruit setting days, total harvesting days and peak harvesting days were studied. The results revealed significant differences in parameters studied except total period of blooming under Tandojam, Sindh conditions. Varieties were classified as early, mid and late season for both provinces. Local varieties had potential for further manipulation in terms of variety improvement to attract growers for extensive ber cultivations under changing global climatic scenario. (author)
Increasing thyroid cancer incidence in Canada, 1970–1996: time trends and age-period-cohort effects
Liu, S; Semenciw, R; Ugnat, A-M; Mao, Y.(State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China)
2001-01-01
We examined time trends in thyroid cancer incidence in Canada by age, time period and birth cohort between 1970 and 1996. Age-specific incidence rates by time period and birth cohort were calculated and age-period-cohort modelling used to estimate effects underlying the observed trends. Overall age-adjusted incidence rates of thyroid cancer doubled, from 3.3 and 1.1 per 100 000 in 1970–72 to 6.8 and 2.2 per 100 000 in 1994–96, among females and males respectively. Almost all the increase betw...
Wang, W.-M.
2008-01-01
We prove that the 1- d quantum harmonic oscillator is stable under spatially localized, time quasi-periodic perturbations on a set of Diophantine frequencies of positive measure. This proves a conjecture raised by Enss-Veselic in their 1983 paper [EV] in the general quasi-periodic setting. The motivation of the present paper also comes from construction of quasi-periodic solutions for the corresponding nonlinear equation.
Generational and time period differences in American adolescents' religious orientation, 1966-2014.
Twenge, Jean M; Exline, Julie J; Grubbs, Joshua B; Sastry, Ramya; Campbell, W Keith
2015-01-01
In four large, nationally representative surveys (N = 11.2 million), American adolescents and emerging adults in the 2010s (Millennials) were significantly less religious than previous generations (Boomers, Generation X) at the same age. The data are from the Monitoring the Future studies of 12th graders (1976-2013), 8th and 10th graders (1991-2013), and the American Freshman survey of entering college students (1966-2014). Although the majority of adolescents and emerging adults are still religiously involved, twice as many 12th graders and college students, and 20%-40% more 8th and 10th graders, never attend religious services. Twice as many 12th graders and entering college students in the 2010s (vs. the 1960s-70s) give their religious affiliation as "none," as do 40%-50% more 8th and 10th graders. Recent birth cohorts report less approval of religious organizations, are less likely to say that religion is important in their lives, report being less spiritual, and spend less time praying or meditating. Thus, declines in religious orientation reach beyond affiliation to religious participation and religiosity, suggesting a movement toward secularism among a growing minority. The declines are larger among girls, Whites, lower-SES individuals, and in the Northeastern U.S., very small among Blacks, and non-existent among political conservatives. Religious affiliation is lower in years with more income inequality, higher median family income, higher materialism, more positive self-views, and lower social support. Overall, these results suggest that the lower religious orientation of Millennials is due to time period or generation, and not to age. PMID:25962174
Generational and time period differences in American adolescents' religious orientation, 1966-2014.
Jean M Twenge
Full Text Available In four large, nationally representative surveys (N = 11.2 million, American adolescents and emerging adults in the 2010s (Millennials were significantly less religious than previous generations (Boomers, Generation X at the same age. The data are from the Monitoring the Future studies of 12th graders (1976-2013, 8th and 10th graders (1991-2013, and the American Freshman survey of entering college students (1966-2014. Although the majority of adolescents and emerging adults are still religiously involved, twice as many 12th graders and college students, and 20%-40% more 8th and 10th graders, never attend religious services. Twice as many 12th graders and entering college students in the 2010s (vs. the 1960s-70s give their religious affiliation as "none," as do 40%-50% more 8th and 10th graders. Recent birth cohorts report less approval of religious organizations, are less likely to say that religion is important in their lives, report being less spiritual, and spend less time praying or meditating. Thus, declines in religious orientation reach beyond affiliation to religious participation and religiosity, suggesting a movement toward secularism among a growing minority. The declines are larger among girls, Whites, lower-SES individuals, and in the Northeastern U.S., very small among Blacks, and non-existent among political conservatives. Religious affiliation is lower in years with more income inequality, higher median family income, higher materialism, more positive self-views, and lower social support. Overall, these results suggest that the lower religious orientation of Millennials is due to time period or generation, and not to age.
TimeÃ¢Â€Â”periodic weak solutions
Eliana Henriques de Brito
1990-03-01
Full Text Available In continuing from previous papers, where we studied the existence and uniqueness of the global solution and its asymptotic behavior as time t goes to infinity, we now search for a time-periodic weak solution u(t for the equation whose weak formulation in a Hilbert space H isddt(uÃ¢Â€Â²,v+ÃŽÂ´(uÃ¢Â€Â²,v+ÃŽÂ±b(u,v+ÃŽÂ²a(u,v+(G(u,v=(h,vwhere: Ã¢Â€Â²=d/dt; (Ã¢Â€Â² is the inner product in H; b(u,v, a(u,v are given forms on subspaces UÃ¢ÂŠÂ‚W, respectively, of H; ÃŽÂ´>0, ÃŽÂ±Ã¢Â‰Â¥0, ÃŽÂ²Ã¢Â‰Â¥0 are constants and ÃŽÂ±+ÃŽÂ²>0; G is the Gateaux derivative of a convex functional J:VÃ¢ÂŠÂ‚HÃ¢Â†Â’[0,Ã¢ÂˆÂž for V=U, when ÃŽÂ±>0 and V=W when ÃŽÂ±=0, hence ÃŽÂ²>0; v is a test function in V; h is a given function of t with values in H.
Cardiac systolic time intervals in fetal monkeys: pre-ejection period.
Murata, Y; Martin, C B; Ikenoue, T; Petrie, R H
1978-10-01
The systolic time intervals of the fetal cardiac cycle were studied by means of simultaneous recordings of electrocardiogram (ECG) and ultrasound Doppler cardiogram (DCG) in chronic preparations of fetal rhesus monkeys. Recordings were made under physiologic conditions as well as during various experimental stresses. The pre-ejection period (PEP) showed no significant relationship with heart rate in the unstressed fetuses, but the acceleration of heart rate induced by epinephrine was accompanied by shortening of PEP. The PEP increased with advancing fetal age. The PEP was inversely correlated with left ventricular end-diastolic pressure and arterial pulse pressure, but showed a positive correlation with both systolic and diastolic arterial blood pressure. The PEP also exhibited strong negative correlation with arterial blood pH. the prolongation was essentially the same whether acidosis was of respiratory or metabolic origin. The PEP increased slightly but significantly during nonacidemic hypoxemia; however, there was no correlation between Pao2 and PEP Epinephrine shortened the PEP significantly, whereas the effect of atropine was inconsistent. Alteration of the plasma glucose level by injection of insulin or glucose did not affect PEP. These findings demonstrate that the PEP may be a useful indicator of fetal cardiac performance, reflecting both myocardial contractility and the hemodynamic state of the cardiovascular system. PMID:30282
Tokmakidis, S P; Volaklis, K A
2000-08-01
The purpose of this study was to investigate the effects of glucose ingestion (GI) at different time periods prior to exercise on blood glucose (BG) levels during prolonged treadmill running. Eight subjects (X+/-SD), age 20+/-0.5yr, bodymass 70.7+/-4.1 kg, height 177+/-4 cm, VO2max 52.8+/-7.8 ml x kg(-1) x min(-1) who underwent different experimental conditions ingested a glucose solution (1 g/kg at 350 ml) 30 min (gl-30), 60 min (gl-60), 90 min (gl-90), and a placebo one 60 min (pl-60) prior to exercise in a counterbalanced design. Afterwards they ran at 65% of VO2max for 1 hour and then at 75 % of VO2max till exhaustion. Fingertip blood samples (10 microl) were drawn every 15 min before and during exercise for the determination of BG levels. Oxygen uptake (VO2), heart rate (HR), and blood lactate (La) were also measured every 15 min during exercise. Peak BG values were reached within 30 min after GI but were different (p affect the duration of treadmill running. The La levels were higher (p affecting the duration of running performance at 75% VO2max. Thus, in order to maintain normoglycaemic levels, pre-exercise glucose supplementation should be given 30 min before the onset of exercise. PMID:10961522
Localized solutions in laser plasma coupled system with periodic time dependence
There are well known varieties of exact nonlinear localized solutions for the laser plasma system which have been studied extensively. In these solutions the ponderomotive pressure of light wave expels and evacuates the electrons from the center creating a cavity of electron density. The electrons are pulled up by the electrostatic force of the ions which are left behind at in the central region. The balance of ponderomotive and the electrostatic forces leads to a configuration wherein the electrons are piled up at the edge region of the solutions. The higher electron density at the edge in turn confines the radiation and prevents its leaking out. Both stationary as well as moving structures with constant group velocities have been obtained and studied in detail in some of our previous work. Here we report a new variety of solutions showing periodic time dependence. These solutions have been shown to exist in both fluid and Particle - in - Cell simulations. A physical understanding of such solutions will also be provided. (author)
Márcio Mourão
Full Text Available We investigated commonly used methods (Autocorrelation, Enright, and Discrete Fourier Transform to estimate the periodicity of oscillatory data and determine which method most accurately estimated periods while being least vulnerable to the presence of noise. Both simulated and experimental data were used in the analysis performed. We determined the significance of calculated periods by applying these methods to several random permutations of the data and then calculating the probability of obtaining the period's peak in the corresponding periodograms. Our analysis suggests that the Enright method is the most accurate for estimating the period of oscillatory data. We further show that to accurately estimate the period of oscillatory data, it is necessary that at least five cycles of data are sampled, using at least four data points per cycle. These results suggest that the Enright method should be more widely applied in order to improve the analysis of oscillatory data.
It's T time: A study on the return period of multivariate problems
Michailidi, Eleni Maria; Balistrocchi, Matteo; Bacchi, Baldassare
2016-04-01
One of the most important tasks a hydrologist must face is the proper estimation of the 'design values' of a natural variable corresponding to a given Return Period, T, of failures of the hydraulic 'structure' to be designed or verified. Sometimes the 'structure' is simply the embankments, the failure of which corresponds to the outflows of flood runoff on the surrounding land. The widely adopted definition of T, in a problem regarding the maxima of hydrological variables, is "the average time elapsing between two successive occurrences of an event exceeding a certain magnitude of the natural variables". If T is referred to the minima, the symmetric definition pertains to the "average time between two periods during which the variable ranges below a given magnitude". Conventional (and the only accepted) approaches for estimation of T involve a single natural variable (i.e. flood-peak of a river at a given cross section, the daily maximum discharge, the maximum daily rainfall depth observed at a given rain-gauge). The method of estimation of T entails a frequency analysis of the variable of interest, where the design value of a given T is needed to design the structure of interest (e.g. dams, sewers). In other words, T is used as the index value to set the assigned risk level for the hydraulic works. However, a univariate approach in complex problems ignores the effect of significant variables interrelation leading to different risk levels for each quantity of interest and resulting in a completely wrong estimate of the risk. For example, if one considers the flood inflow in a lake around which cities and villages are positioned, the variable to be investigated in relation to the risk assessment is the lake water level. It is obvious that the same water level may occur from very different flood hydrographs, even when the same initial water level and the same rate curve of outflows are considered. This is a consequence of the interaction of at least three joint
Johansen, Søren Glud; Thorstenson, Anders
2008-01-01
We extend well-known formulae for the optimal base stock of the inventory system with continuous review and constant lead time to the case with periodic review and stochastic, sequential lead times. Our extension uses the notion of the 'extended lead time'. The derived performance measures...
Simonsen, Poul Erik; Niemann, L.; Meyrowitsch, Dan Wolf
1997-01-01
The circadian periodicity of Wuchereria bancrofti microfilarial (mf) intensities in peripheral blood was analysed in a group of infected individuals from an endemic community in north-eastern Tanzania. The mf density was quantified at two-hourly intervals for 24 hours. A clear nocturnal periodic...
Li, Fang; Liang, Xing; Shen, Wenxian
2015-01-01
In this series of papers, we investigate the spreading and vanishing dynamics of time almost periodic diffusive KPP equations with free boundaries. Such equations are used to characterize the spreading of a new species in time almost periodic environments with free boundaries representing the spreading fronts. In the first part of the series, we showed that a spreading-vanishing dichotomy occurs for such free boundary problems (see [16]). In this second part of the series, we investigate the ...
Qiranrong Tan; Weigen Wu; Jun Li; Xing Yin
2011-01-01
This paper deals with the problem of delay-dependent stability criterion of uncertain periodic switched recurrent neural networks with time-varying delays. When uncertain discrete-time recurrent neural network is a periodic system, it is expressed as switched neural network for the finite switching state. Based on the switched quadratic Lyapunov functional approach (SQLF) and free-weighting matrix approach (FWM), some linear matrix inequality criteria are found to guarantee the delay-dependen...
Survival of Bacillus pumilus spores for a prolonged period of time in real space conditions.
Vaishampayan, Parag A; Rabbow, Elke; Horneck, Gerda; Venkateswaran, Kasthuri J
2012-05-01
To prevent forward contamination and maintain the scientific integrity of future life-detection missions, it is important to characterize and attempt to eliminate terrestrial microorganisms associated with exploratory spacecraft and landing vehicles. Among the organisms isolated from spacecraft-associated surfaces, spores of Bacillus pumilus SAFR-032 exhibited unusually high resistance to decontamination techniques such as UV radiation and peroxide treatment. Subsequently, B. pumilus SAFR-032 was flown to the International Space Station (ISS) and exposed to a variety of space conditions via the European Technology Exposure Facility (EuTEF). After 18 months of exposure in the EXPOSE facility of the European Space Agency (ESA) on EuTEF under dark space conditions, SAFR-032 spores showed 10-40% survivability, whereas a survival rate of 85-100% was observed when these spores were kept aboard the ISS under dark simulated martian atmospheric conditions. In contrast, when UV (>110 nm) was applied on SAFR-032 spores for the same time period and under the same conditions used in EXPOSE, a ∼7-log reduction in viability was observed. A parallel experiment was conducted on Earth with identical samples under simulated space conditions. Spores exposed to ground simulations showed less of a reduction in viability when compared with the "real space" exposed spores (∼3-log reduction in viability for "UV-Mars," and ∼4-log reduction in viability for "UV-Space"). A comparative proteomics analysis indicated that proteins conferring resistant traits (superoxide dismutase) were present in higher concentration in space-exposed spores when compared to controls. Also, the first-generation cells and spores derived from space-exposed samples exhibited elevated UVC resistance when compared with their ground control counterparts. The data generated are important for calculating the probability and mechanisms of microbial survival in space conditions and assessing microbial contaminants
Spigaglia, Patrizia; Mastrantonio, Paola
2004-11-01
Recent studies have shown that Clostridium difficile strains with variant toxins and those with resistance to macrolide-lincosamide-streptogramin B (MLSB) are increasingly causing severe disease and outbreaks in hospital settings. Here, the pathogenicity locus (PaLoc), the acquisition of binary toxin, and the genotypic and phenotypic characteristics of antibiotic resistance of 74 C. difficile clinical strains isolated from symptomatic patients in Italy during different time periods were studied. These strains were found to belong to two different lineages, and those isolated before 1991 were genetically unrelated to the more recent strains. The majority of recent C. difficile strains showed variations in toxin genes and in the toxin negative regulator (tcdC) and had the binary toxin. In 62 % of them, variations in tcdC and the presence of the binary toxin were associated. Five classes of susceptibility/resistance pattern (EC-a to -e) for erythromycin and clindamycin were identified in all strains studied. Most of the recent isolates belonged to EC-d and EC-e and, although erythromycin-resistant in vitro, did not harbour the commonly associated ermB determinant. Interestingly, two strains of the EC-d class were resistant to clindamycin only after induction with subinhibitory concentrations of the antibiotic. A decrease in tetracycline and chloramphenicol MIC values was also observed in the recently isolated strains, associated with less frequent detection of the catD and tetM genes. Two tetM-positive strains were resistant in vitro only after induction with subinhibitory concentrations of the antibiotic. The acquisition of the binary toxin, the possible increase in toxin production due to a mutated negative regulator and a decrease in the fitness cost as a result of lower levels of antibiotic resistance or other mechanisms may have led to the successful establishment of these new phenotypes, with potentially serious clinical implications. PMID:15496392
Assume that the Aubry set of the time-periodic positive definite Lagrangian L consists of one hyperbolic 1-periodic orbit. We provide an upper bound estimate of the rate of convergence of the family of new Lax–Oleinik type operators associated with L introduced by the authors in Wang and Yan (2012 Commun. Math. Phys. 309 663–91). In addition, we construct an example where the Aubry set of a time-independent positive definite Lagrangian system consists of one hyperbolic periodic orbit and the rate of convergence of the Lax–Oleinik semigroup cannot be better than O(1/t) as t → +∞
Yongkun Li; Lei Wang; Yu Fei
2014-01-01
A class of shunting inhibitory cellular neural networks of neutral type with time-varying delays in the leakage term on time scales is proposed. Based on the exponential dichotomy of linear dynamic equations on time scales, fixed point theorems, and calculus on time scales we obtain some sufficient conditions for the existence and global exponential stability of periodic solutions for that class of neural networks. The results of this paper are completely new and complementary to the previous...
Li, Yongkun; Meng, Xiaofang; Xiong, Lianglin
2015-01-01
In this paper, a class of neutral type high-order Hopfield neural networks with mixed time-varying delays and leakage delays on time scales is proposed. Based on the exponential dichotomy of linear dynamic equations on time scales, Banach's fixed point theorem and the theory of calculus on time scales, some sufficient conditions are obtained for the existence and global exponential stability of pseudo almost periodic solutions for this class of neural networks. Our results are completely new....
Maintaining high precision of isotope ratio analysis over extended periods of time
Full text: The measurement of stable isotope ratios from natural material often requires a very high precision. This is especially true when the isotopic signatures in question are small, e.g. when - studying water stress in plants through investigation of δ13C in tree rings (up to 3 per mille variation); - following the addition of fossil carbon in atmospheric CO2 (increase of 0.025 per mille/year); - investigating δ18O or δD of water in ice cores in order to reconstruct climatic change in the past (1-2 per mille and 20-40 per mille respectively). In order to maintain such high precision over extended periods of time we have installed a rigorous quality control of isotopic measurements in our isotope laboratory. The most important guideline for establishing such a scheme is to understand the measurement process in great detail and to treat samples and reference material in a closely identical fashion. For examples tree ring isotopes are determined in a Laser Ablation experiment where the sample material is ablated and transported to combustion furnace for conversion to CO2. In the same chamber, we include cellulose as an internal reference. In between sample ablation shots we hit the cellulose and use the resulting CO2 for scale correction. δ13C analysis of CO2 in air samples from around the globe is based on whole air standards measured on the same multi-sample carousel on a daily basis. External precision of 0.013 per mille has been maintained over a record of the last four years, monitored through a daily measurement of a quality control air through the same inlet line. Water isotopic analysis is made using injection of plain water into a high temperature (>1400 deg. C) reactor filled with (glassy) carbon using a gas tight syringe. The precision for both, 18O and D/H is monitored by injecting local reference water samples interspersed with the normal sample water. Examples of the techniques and the associated QA scheme will be presented and discussed
Chunhong Li; Chuanzhi Bai
2010-01-01
In this paper, a Hopfield neural network with neutral time-varying delays is investigated by using the continuation theorem of Mawhin's coincidence degree theory and some analysis technique. Without assuming the continuous differentiability of time-varying delays, sufficient conditions for the existence of the periodic solutions are given. The result of this paper is new and extends previous known result.
Johansen, Søren Glud; Thorstenson, Anders
We show that well-known textbook formulae for determining the optimal base stock of the inventory system with continuous review and constant lead time can easily be extended to the case with periodic review and stochastic, sequential lead times. The provided performance measures and conditions for...
Johansen, Søren Glud; Thorstenson, Anders
2008-01-01
We extend well-known formulae for the optimal base stock of the inventory system with continuous review and constant lead time to the case with periodic review and stochastic, sequential lead times. Our extension uses the notion of the ‘extended lead time’. The derived performance measures are...... exact for Poisson demands....
2010-10-01
... 45 Public Welfare 2 2010-10-01 2010-10-01 false What time frames and guidelines apply regarding the obligation and liquidation periods for NEW Program funds? 287.55 Section 287.55 Public Welfare... NEW Program Funding § 287.55 What time frames and guidelines apply regarding the obligation...
[Local fractal analysis of noise-like time series by all permutations method for 1-115 min periods].
Panchelyuga, V A; Panchelyuga, M S
2015-01-01
Results of local fractal analysis of 329-per-day time series of 239Pu alpha-decay rate fluctuations by means of all permutations method (APM) are presented. The APM-analysis reveals in the time series some steady frequency set. The coincidence of the frequency set with the Earth natural oscillations was demonstrated. A short review of works by different authors who analyzed the time series of fluctuations in processes of different nature is given. We have shown that the periods observed in those works correspond to the periods revealed in our study. It points to a common mechanism of the phenomenon observed. PMID:26016038
IDENTIFICATION OF PERIODIC AUTOREGRESSIVE MOVING-AVERAGE TIME SERIES MODELS WITH R
Hazem I. El Shekh Ahmed
2014-01-01
Full Text Available Periodic autoregressive moving average PARMA process extend the classical autoregressive moving average ARMA process by allowing the parameters to vary with seasons. Model identification is the identification of a possible model based on an available realization, i.e., determining the type of the model with appropriate orders. The Periodic Autocorrelation Function (PeACF and the Periodic Partial Autocorrelation Function (PePACF serve as useful indicators of the correlation or of the dependence between the values of the series so that they play an important role in model identification. The identification is based on the cut-off property of the Periodic Autocorrelation Function (PeACF. We derive an explicit expression for the asymptotic variance of the sample PeACF to be used in establishing its bands. Therefore, we will get in this study a new structure of the periodic autocorrelation function which depends directly to the variance that will derived to be used in establishing its bands for the PMA process over the cut-off region and we have studied the theoretical side and we will apply some simulated examples with R which agrees well with the theoretical results.
Magnetic Cycles and Rotation Periods of Late Type Stars from photometric time series
Mascareño, A Suárez; Hernández, J I González
2016-01-01
We investigate the photometric modulation induced by magnetic activity cycles and study the relationship between rotation period and activity cycle(s) in late-type (FGKM) stars. We analyse light-curves spanning up to 9 years of 125 nearby stars provided by the ASAS survey. The sample is mainly conformed by low-activity main sequence late A to mid M-type stars. A search is performed for short (days) and long-term (years) periodic variations in the photometry. We modelled with combinations of sinusoids the light-curves to measure the properties of these periodic signals. To provide a better statistical interpretation of our results we complement them with the results from previous similar works. We have been able to measure long-term photometric cycles of 47 stars. Rotational modulation was also detected and rotational periods measured in 36 stars. For 28 stars we have simultaneous measurements of both, activity cycles and rotational periods, being 17 of them M-type stars. From sinusoidal fits we measured both ...
Cermanová, Pavlína
Köln : Böhlau, 2015 - (Schmieder, F.), s. 141-164 ISBN 978-3-412-50194-5. - (Beihefte zum Archiv für Kulturgeschichte. 77) EU Projects: European Commission(XE) 263672 Institutional support: RVO:67985955 Keywords : prophecies * Hussite period * Antichrist * Apocalypse * reform Subject RIV: AA - Philosophy ; Religion
Yingwei Li
2013-01-01
Full Text Available The global exponential stability issues are considered for almost periodic solution of the neural networks with mixed time-varying delays and discontinuous neuron activations. Some sufficient conditions for the existence, uniqueness, and global exponential stability of almost periodic solution are achieved in terms of certain linear matrix inequalities (LMIs, by applying differential inclusions theory, matrix inequality analysis technique, and generalized Lyapunov functional approach. In addition, the existence and asymptotically almost periodic behavior of the solution of the neural networks are also investigated under the framework of the solution in the sense of Filippov. Two simulation examples are given to illustrate the validity of the theoretical results.
Allen, Matthew S.; Sracic, Michael W.; Chauhan, Shashank;
2011-01-01
Many important systems, such as wind turbines, helicopters and turbomachinery, must be modeled with linear time-periodic equations of motion to correctly predict resonance phenomena. Time periodic effects in wind turbines might arise due to blade-to-blade manufacturing variations, stratification in......, safety, and to produce economical power. This work presents a system identification methodology that can be used to identify models for linear, periodically time-varying systems when the input forces are unmeasured, broadband and random. The methodology is demonstrated for the well-known Mathieu...... oscillator and then used to interrogate simulated measurements from a rotating wind turbine. The measurements were simulated for a 5 MW turbine modeled in the HAWC2 simulation code, which includes both structural dynamic and aerodynamic effects. This simulated system identification provides insights into the...
Li, Fang; Liang, Xing; Shen, Wenxian
2016-08-01
In this series of papers, we investigate the spreading and vanishing dynamics of time almost periodic diffusive KPP equations with free boundaries. Such equations are used to characterize the spreading of a new species in time almost periodic environments with free boundaries representing the spreading fronts. In the first part of the series, we showed that a spreading-vanishing dichotomy occurs for such free boundary problems (see [16]). In this second part of the series, we investigate the spreading speeds of such free boundary problems in the case that the spreading occurs. We first prove the existence of a unique time almost periodic semi-wave solution associated to such a free boundary problem. Using the semi-wave solution, we then prove that the free boundary problem has a unique spreading speed.
liu, weiwei; Huangfu, Hao; Xiong, Jing;
2014-01-01
of the time period of thermal adaption were obtained on the basis of the data from a long-term field survey conducted in two typical naturally ventilated offices located in Changsha, China. The results showed that the occupants need to take 4.25 days to fully adapt to a step-change in outdoor air...... adaption indicated that the psychological adaption mode can speed up the process of thermal adaption to the variation in the outdoor climate condition. This study presented a new insight into the feedback from the thermal adaption modes to occupant thermal comfort.......This study proposed a method to determine time period of thermal adaption for occupants in naturally ventilated building, and analyzed the synergistic and separate feedback effect of the physical and psychological adaption modes on the time period of thermal adaption. Using the method, the values...
Pelgrin, Florian; Sylvain, Arnaud; Heyer, Eric
2004-01-01
While a number of studies have demonstrated the importance of factor utilization in economic analysis, the impact of operating hours and/or hours of work in the production function remains largely unknown, particularly in terms of the capital operating time. Using French data on industrial firms for the period 1989 to 2001, we estimate a Cobb-Douglas production function that considers the stocks and both the capital operating time and the working time. We draw on the framework defined by Blun...
Bone cancer cases in 1250 women exposed to radium while working in the luminous watch-dial industry between 1913 and 1929 were analyzed for times of appearance (''latency periods'') and incidence rates over time after first exposure. The lowest radium intake dose associated with bone cancer, among 751 women whose intake doses had been determined, was 202.5 μCi. Mean and median bone cancer latency periods tended to decline, but average survival among women without bone cancer also decreased with increasing intake level. Bone cancer incidence rates over time were compared in 2 intake-dose groups (200 to 749 and greater than or equal to 750 μCi) by means of an actuarial method that takes competing risks into account. Incidence rates were consistently higher in the higher intake-dose group versus the lower dose group at each 5-year period after first exposure. The variability in the odds ratios across the time periods was not statistically significant, and the actuarial method provided little evidence for an effect of intake dose on the pattern of incidence rate over time. With the use of similar methods, no significant variability was evident in the relative odds of bone cancer over time after exposure between one group of women first exposed to radium at less than 18 years of age and another group exposed when 18 or more years old
FAN JianXing; YANG HuaZhong; WANG Hui; YAN XiaoLang; HOU ChaoHuan
2007-01-01
Phase noise analysis of an oscillator is implemented with its periodic time-varying small signal state equations by perturbing the autonomous large signal state equations of the oscillator. In this paper, the time domain steady solutions of oscillators are perturbed with traditional regular method; the periodic time-varying Jocobian modulus matrices are decomposed with Sylvester theorem, and on the resulting space spanned by periodic vectors, the conditions under which the oscillator holds periodic steady states with any perturbations are analyzed. In this paper, stochastic calculus is applied to disclose the generation process of phase noise and calculate the phase jitter of the oscillator by injecting a pseudo sinusoidal signal in frequency domain, representing the white noise, and a δ correlation signal in time domain into the oscillator. Applying the principle of frequency modulation, we learned how the power-law and the Lorentzian spectrums are formed. Their relations and the Lorentzian spectrums of harmonics are also worked out. Based on the periodic Jacobian modulus matrix, the simple algorithms for Floquet exponents and phase noise are constructed, as well as a simple case is demonstrated. The analysis difficulties and the future directions for the phase noise of oscillators are also pointed out at the end.
Formulation of a Combined Transportation and Inventory Optimization Model with Multiple Time Periods
G.Krishnakumari,
2016-03-01
Full Text Available Most distribution network design models existing in the literature have focused on minimizing the costs of inventory and transportation. During the analysis of supply chain of currency management problem it is observed that the transportation of currency from various sources to various destinations and the required inventory to be maintained to meet the emerging demands requires formulation of a combined problem. This framework aims to support the coordination of inventory and transportation activities to properly manage the inventory profiles and currency flows between source locations and distribution centers. This paper considers a multi-period inventory and transportation model for a single commodity. The key contribution of this paper is, a mathematical programming formulation of transportation cum inventory problem is proposed and an algorithm for this new formulation as a multi period decision process is intended. A numerical example of currency transportation cum inventory is presented to illustrate the proposed algorithm
DOBSON, Matthew
2014-01-01
This work presents a generalization of the Kraynik-Reinelt (KR) boundary conditions for nonequilibrium molecular dynamics simulations. In the simulation of steady, homogeneous flows with periodic boundary conditions, the simulation box moves with the flow, and it is possible for particle replicas to become arbitrarily close, causing a breakdown in the simulation. The KR boundary conditions avoid this problem for planar elongational flow and general planar mixed flow [J. Chem. Phys 133, 14116 ...
Gang FTP scheduling of periodic and parallel rigid real-time tasks
Goossens, Joël
2010-01-01
In this paper we consider the scheduling of periodic and parallel rigid tasks. We provide (and prove correct) an exact schedulability test for Fixed Task Priority (FTP) Gang scheduler sub-classes: Parallelism Monotonic, Idling, Limited Gang, and Limited Slack Reclaiming. Additionally, we study the predictability of our schedulers: we show that Gang FJP schedulers are not predictable and we identify several sub-classes which are actually predictable. Moreover, we extend the definition of rigid, moldable and malleable jobs to recurrent tasks.
Kamimori, Gary H.; McLellan, Tom M.; Tate, Charmaine M.; Voss, David M.; Niro, Phil; Lieberman, Harris R.
2014-01-01
Rationale Various occupational groups are required to maintain optimal physical and cognitive function during overnight periods of wakefulness, often with less than optimal sleep. Strategies are required to help mitigate the impairments in cognitive function to help sustain workplace safety and productivity. Objectives To test the effectiveness of repeated 200 mg doses of caffeine on cognitive function and live-fire marksmanship with soldiers during three successive nights of sustained wakefu...
Periodic Solution of a Nonautonomous Diffusive Food Chain System of Three Species with Time Delays
Zheng-qiu Zhang; Xian-wu Zeng; Zhi-cheng Wang
2003-01-01
By using the continuation theorem of coincidence degree theory, the existence of a positive periodic solution for a nonautonomous diffusive food chain system of three species.dx1(t)/dt = xl(t)[r1(t) - a11(t)x1(t) - a12(t)x2(t)] + D1(t)[y(t) - x1(t)],dx2 (t)/dt = x2(t)[-r2(t) + a21(t)x1(t - τ1) - a22(t)x2(t) - a23(t)x3(t)],dx3 (t)/dt = x3(t)[-r3(t) + a32(t)x2(t - τ2) - a33(t)x3(t)],dy(t)/dt = y(t)[r4(t) - a44(t)y(t)] + D2(t)[x1 (t) - y(t)],is established, where ri(t), aii(t) (i= 1, 2, 3, 4), Di(t) (i = 1, 2), a12(t), a21 (t), a23(t) and a32(t) are all positive periodic continuous functions with period w ＞ 0, τi(i = 1, 2) are positive constants.
Looking for granulation and periodicity imprints in the sunspot time series
Lopes, Ilidio
2015-01-01
The sunspot activity is the end result of the cyclic destruction and regeneration of magnetic fields by the dynamo action. We propose a new method to analyze the daily sunspot areas data recorded since 1874. By computing the power spectral density of daily data series using the Mexican hat wavelet, we found a power spectrum with a well-defined shape, characterized by three features. The first term is the 22 yr solar magnetic cycle, estimated in our work to be of 18.43 yr. The second term is related to the daily volatility of sunspots. This term is most likely produced by the turbulent motions linked to the solar granulation. The last term corresponds to a periodic source associated with the solar magnetic activity, for which the maximum of power spectral density occurs at 22.67 days. This value is part of the 22-27 day periodicity region that shows an above-average intensity in the power spectra. The origin of this 22.67 day periodic process is not clearly identified, and there is a possibility that it can be...
Yongkun Li
2014-01-01
Full Text Available A class of shunting inhibitory cellular neural networks of neutral type with time-varying delays in the leakage term on time scales is proposed. Based on the exponential dichotomy of linear dynamic equations on time scales, fixed point theorems, and calculus on time scales we obtain some sufficient conditions for the existence and global exponential stability of periodic solutions for that class of neural networks. The results of this paper are completely new and complementary to the previously known results even if the time scale =ℝ or ℤ. Moreover, we present illustrative numerical examples to show the feasibility of our results.
Baskaran, Santhi
2010-01-01
Energy consumption is a critical design issue in real-time systems, especially in battery- operated systems. Maintaining high performance, while extending the battery life between charges is an interesting challenge for system designers. Dynamic Voltage Scaling (DVS) allows a processor to dynamically change speed and voltage at run time, thereby saving energy by spreading run cycles into idle time. Knowing when to use full power and when not, requires the cooperation of the operating system scheduler. Usually, higher processor voltage and frequency leads to higher system throughput while energy reduction can be obtained using lower voltage and frequency. Instead of lowering processor voltage and frequency as much as possible, energy efficient real-time scheduling adjusts voltage and frequency according to some optimization criteria, such as low energy consumption or high throughput, while it meets the timing constraints of the real-time tasks. As the quantity and functional complexity of battery powered porta...
Steady-state time-periodic finite element analysis of a brushless DC motor drive considering motion
Jagieła Mariusz
2015-09-01
Full Text Available This paper aims at providing a framework for comprehensive steady-state time-domain analysis of rotating machines considering motion. The steady-state waveforms of electromagnetic and circuit quantities are computed via iterative solution of the nonlinear field-circuit-and-motion problem with constraints of time periodicity. The cases with forced speed and forced load torque are considered. A comparison of execution times with a conventional time-stepping transient model is carried out for two different machines. The numerical stability of a time-periodic model with forced speed is shown to be worse than that of traditional transient time-stepping one, although the model converges within a reasonable number of iterations. This is not the case if forced load via equation of mechanical balance is accounted for. To ensure convergence of the iterative process the physical equation of motion is replaced by the fixed-point equation. In this way the model delivers time-periodic solutions regarding not only the electromagnetic quantities but also the rotational speed.
Santhi Baskaran
2010-12-01
Full Text Available Energy consumption is a critical design issue in real-time systems, especially in battery- operated systems. Maintaining high performance, while extending the battery life between charges is an interesting challenge for system designers. Dynamic Voltage Scaling (DVS allows a processor to dynamically change speed and voltage at run time, thereby saving energy by spreading run cycles into idle time.Knowing when to use full power and when not, requires the cooperation of the operating system scheduler. Usually, higher processor voltage and frequency leads to higher system throughput whileenergy reduction can be obtained using lower voltage and frequency. Instead of lowering processorvoltage and frequency as much as possible, energy efficient real-time scheduling adjusts voltage andfrequency according to some optimization criteria, such as low energy consumption or high throughput,while it meets the timing constraints of the real-time tasks. As the quantity and functional complexity ofbattery powered portable devices continues to raise, energy efficient design of such devices has becomeincreasingly important. Many real-time scheduling algorithms have been developed recently to reduceenergy consumption in the portable devices that use DVS capable processors. Extensive power awarescheduling techniques have been published for energy reduction, but most of them have been focusedsolely on reducing the processor energy consumption. While the processor is one of the major powerhungry units in the system, other peripherals such as network interface card, memory banks, disks alsoconsume significant amount of power. Dynamic Power Down (DPD technique is used to reduce energyconsumption by shutting down the processing unit and peripheral devices, when the system is idle. Threealgorithms namely Red Tasks Only (RTO, Blue When Possible (BWP and Red as Late as Possible (RLPare proposed in the literature to schedule the real-time tasks in Weakly-hard real-time
Advantages and Drawbacks of Applying Periodic Time-Variant Modal Analysis to Spur Gear Dynamics
Pedersen, Rune; Santos, Ilmar; Hede, Ivan Arthur
2010-01-01
ensure sufficient accuracy of the results. The method of time-variant modal analysis is applied, and the changes in the fundamental and the parametric resonance frequencies as a function of the rotational speed of the gears, are found. By obtaining the stationary and parametric parts of the time......-dependent modes shapes, the importance of the time-varying component relative to the stationary component is investigated and quantified. The method used for calculation and subsequent sorting of the left and right eigenvectors based on a first order Taylor expansion is explained. The advantages and drawbacks of...
Synchronous states in time-delay coupled periodic oscillators: A stability criterion
Correa, Diego Paolo F.; Piqueira, José Roberto C.
2013-08-01
There are several works showing that nonzero time delay between nodes in an oscillator network can be responsible for several kinds of behavior as synchronization and chaos. Here, by using the Lyapunov linearizing method, in a system of two coupled oscillators derived as a particular case of the full connected network, it is shown that the time delay parameter has two sets of values: one that destabilizes the whole system and other that implies stability. Besides, there is a set of time delay values responsible for chaotic behaviors, even in a simple coupled oscillators system.
Space-time kriging of precipitation variability in Turkey for the period 1976-2010
Raja, Nussaïbah B.; Aydin, Olgu; Türkoğlu, Necla; Çiçek, Ihsan
2016-03-01
The purpose of this study is to revaluate the changing spatial and temporal trends of precipitation in Turkey. Turkey is located in one of the regions at greatest risk from the potential effects of climate change. Since the 1970s, a decreasing trend in annual precipitation has been observed, in addition to an increasing number of precipitation-related natural hazards such as floods, extreme precipitation, and droughts. An understanding of the temporal and spatial characteristics of precipitation is therefore crucial to hazard management as well as planning and managing water resources, which depend heavily on precipitation. The ordinary kriging method was employed to interpolate precipitation estimates using precipitation records from 228 meteorological stations across the country for the period 1976-2010. A decreasing trend was observed across the Central Anatolian region, except for 1996-2000 which saw an increase in precipitation. However, this same period is identified as the driest year in Eastern and South Eastern Anatolia. The Eastern Black Sea region has the highest precipitation in the country; after 1996, an increase in annual precipitation in this region is observed. An overall reduction is also seen in southwest Turkey, with less variation in precipitation.
Chunhong Li
2010-03-01
Full Text Available In this paper, a Hopfield neural network with neutral time-varying delays is investigated by using the continuation theorem of Mawhin's coincidence degree theory and some analysis technique. Without assuming the continuous differentiability of time-varying delays, sufficient conditions for the existence of the periodic solutions are given. The result of this paper is new and extends previous known result.
Kim, M.; Harman, C. J.
2013-12-01
The distribution of water travel times is one of the crucial hydrologic characteristics of the catchment. Recently, it has been argued that a rigorous treatment of travel time distributions should allow for their variability in time because of the variable fluxes and partitioning of water in the water balance, and the consequent variable storage of a catchment. We would like to be able to observe the structure of the temporal variations in travel time distributions under controlled conditions, such as in a soil column or under irrigation experiments. However, time-variable travel time distributions are difficult to observe using typical active and passive tracer approaches. Time-variability implies that tracers introduced at different times will have different travel time distributions. The distribution may also vary during injection periods. Moreover, repeat application of a single tracer in a system with significant memory leads to overprinting of break-through curves, which makes it difficult to extract the original break-through curves, and the number of ideal tracers that can be applied is usually limited. Recognizing these difficulties, the PERTH (PERiodic Tracer Hierarchy) method has been developed. The method provides a way to estimate time-variable travel time distributions by tracer experiments under controlled conditions by employing a multi-tracer hierarchy under periodical hydrologic forcing inputs. The key assumption of the PERTH method is that as time gets sufficiently large relative to injection time, the average travel time distribution of two distinct ideal tracers injected during overlapping periods become approximately equal. Thus one can be used as a proxy for the other, and the breakthrough curves of tracers applied at different times in a periodic forcing condition can be separated from one another. In this study, we tested the PERTH method numerically for the case of infiltration at the plot scale using HYDRUS-1D and a particle
Nujaba Binte Kabir
2012-06-01
Full Text Available The Features of the Chinese wood frame buildings are same in character from dynasty to dynasty. The study concentrates on 9 Chinese wood frame buildings from Tang to Yuan dynasty and tries to relate these buildings with the text described in a building manual book published in Song dynasty Yingzao fashi. The features of some buildings match with the text described in the book some do not. But on the other hand Liang Sicheng, scholar of Chinese architecture in his book claimed that Chinese wood frame architecture has a unique system of characteristics (Liang, 1984. The system of wood frame Chinese architecture did not change but the proportion of the features has changed in different dynasty. The aim of the paper is to compare the features of the buildings those have been studied according to Yingzao fashi with Liang's observation on the change of building style in different periods.
A study of mandibular fractures over a 5-year period of time: A retrospective study
Ashish Vyas
2014-01-01
Full Text Available Objective: This study aims to evaluate and compare with the existing literature on the etiology, pattern, gender, and anatomical distribution of mandibular fractures. Materials and Methods: The data of 225 cases were analyzed over a period of 5 years between March 2009 and November 2013. Of this 110 were unilateral, 23 bilateral, 18 symphysis and 74 multiple fractures. Results: Males are more affected than females.The peak incidence rate is occurring in 30-35 years of age group. The most common fracture site is parasymphysis and least common site is ramus of mandible. The most common etiological factor is road traffic accident (RTA (45.3% followed by falls (42.6%, assaults (8.9%, sport injuries (2.2%, and gunshot wounds (0.89%. Conclusion: Thus, we conclude that RTA is the leading cause of mandibular fractures and males are more affected. The most common site is parasymphysis fracture in association with angle fracture. We observed that gender was significantly associated with body and angle fracture (P = 0.04 and significant relationship between etiology with multiple site fracture such as (parasymphysis-angle, (body-condyle, (body-angle, and (symphysis-condyle was observed (P ≤ 0.05.
Analysis of log-periodic power law singularity patterns in time series related to credit risk
Wosnitza, Jan Henrik; Sornette, Didier
2015-04-01
The log-periodic (super-exponential) power law singularity (LPPLS) has become a promising tool for predicting extreme behavior of self-organizing systems in natural sciences and finance. Some researchers have recently proposed to employ the LPPLS on credit risk markets. The review article at hand summarizes four papers in this field and shows how they are linked. After structuring the research questions, we collect the corresponding answers from the four articles. This eventually gives us an overall picture of the application of the LPPLS to credit risk data. Our literature review begins with grounding the view that credit default swap (CDS) spreads are hotbeds for LPPLS patterns and it ends up with drawing attention to the recently proposed alarm index for the prediction of institutional bank runs. By presenting a new field of application for the LPPLS, the reviewed strand of literature further substantiates the LPPLS hypothesis. Moreover, the results suggest that CDS spread trajectories belong to a different universality class than, for instance, stock prices.
Hongmei Zhang; Fawang Liu
2007-01-01
In this paper, the space-time Riesz fractional partial differential equations with periodic conditions are considered. The equations are obtained from the integral partial differential equation by replacing the time derivative with a Caputo fractional derivative and the space derivative with Riesz potential. The fundamental solutions of the space Riesz fractional partial differential equation (SRFPDE) and the space-time Riesz fractional partial differential equation (STRFPDE) are discussed, respectively. Using methods of Fourier series expansion and Laplace transform, we derive the explicit expressions of the fundamental solutions for the SRFPDE and the STRFPDE, respectively.
Carvalho, Fabiana M.; Chaim, Khallil T.; Sanchez, Tiago A.; de Araujo, Draulio B.
2016-01-01
The updating of prospective internal models is necessary to accurately predict future observations. Uncertainty-driven internal model updating has been studied using a variety of perceptual paradigms, and have revealed engagement of frontal and parietal areas. In a distinct literature, studies on temporal expectations have also characterized a time-perception network, which relies on temporal orienting of attention. However, the updating of prospective internal models is highly dependent on temporal attention, since temporal attention must be reoriented according to the current environmental demands. In this study, we used functional magnetic resonance imaging (fMRI) to evaluate to what extend the continuous manipulation of temporal prediction would recruit update-related areas and the time-perception network areas. We developed an exogenous temporal task that combines rhythm cueing and time-to-contact principles to generate implicit temporal expectation. Two patterns of motion were created: periodic (simple harmonic oscillation) and non-periodic (harmonic oscillation with variable acceleration). We found that non-periodic motion engaged the exogenous temporal orienting network, which includes the ventral premotor and inferior parietal cortices, and the cerebellum, as well as the presupplementary motor area, which has previously been implicated in internal model updating, and the motion-sensitive area MT+. Interestingly, we found a right-hemisphere preponderance suggesting the engagement of explicit timing mechanisms. We also show that the periodic motion condition, when compared to the non-periodic motion, activated a particular subset of the default-mode network (DMN) midline areas, including the left dorsomedial prefrontal cortex (DMPFC), anterior cingulate cortex (ACC), and bilateral posterior cingulate cortex/precuneus (PCC/PC). It suggests that the DMN plays a role in processing contextually expected information and supports recent evidence that the DMN may
Fabiana Mesquita Carvalho
2016-06-01
Full Text Available The updating of prospective internal models is necessary to accurately predict future observations. Uncertainty-driven internal model updating has been studied using a variety of perceptual paradigms, and have revealed engagement of frontal and parietal areas. In a distinct literature, studies on temporal expectations have also characterized a time-perception network, which relies on temporal orienting of attention. However, the updating of prospective internal models is highly dependent on temporal attention, since temporal attention must be reoriented according to the current environmental demands. In this study we used fMRI to evaluate to what extend the continuous manipulation of temporal prediction would recruit update-related areas and the time-perception network areas. We developed an exogenous temporal task that combines rhythm cueing and time-to-contact principles to generate implicit temporal expectation. Two patterns of motion were created: periodic (simple harmonic oscillation and non-periodic (harmonic oscillation with variable acceleration. We found that non-periodic motion engaged the exogenous temporal orienting network, which includes the ventral premotor and inferior parietal cortices, and the cerebellum, as well as the presupplementary motor area, which has previously been implicated in internal model updating, and the motion-sensitive area MT+. Interestingly, we found a right-hemisphere preponderance suggesting the engagement of explicit timing mechanisms. We also show that the periodic motion condition, when compared to the non-periodic motion, activated a particular subset of the default-mode network (DMN midline areas, including the left dorsomedial prefrontal cortex, anterior cingulate cortex, and bilateral posterior cingulate cortex/precuneus. It suggests that the DMN plays a role in processing contextually expected information and supports recent evidence that the DMN may reflect the validation of prospective internal
Carvalho, Fabiana M; Chaim, Khallil T; Sanchez, Tiago A; de Araujo, Draulio B
2016-01-01
The updating of prospective internal models is necessary to accurately predict future observations. Uncertainty-driven internal model updating has been studied using a variety of perceptual paradigms, and have revealed engagement of frontal and parietal areas. In a distinct literature, studies on temporal expectations have also characterized a time-perception network, which relies on temporal orienting of attention. However, the updating of prospective internal models is highly dependent on temporal attention, since temporal attention must be reoriented according to the current environmental demands. In this study, we used functional magnetic resonance imaging (fMRI) to evaluate to what extend the continuous manipulation of temporal prediction would recruit update-related areas and the time-perception network areas. We developed an exogenous temporal task that combines rhythm cueing and time-to-contact principles to generate implicit temporal expectation. Two patterns of motion were created: periodic (simple harmonic oscillation) and non-periodic (harmonic oscillation with variable acceleration). We found that non-periodic motion engaged the exogenous temporal orienting network, which includes the ventral premotor and inferior parietal cortices, and the cerebellum, as well as the presupplementary motor area, which has previously been implicated in internal model updating, and the motion-sensitive area MT+. Interestingly, we found a right-hemisphere preponderance suggesting the engagement of explicit timing mechanisms. We also show that the periodic motion condition, when compared to the non-periodic motion, activated a particular subset of the default-mode network (DMN) midline areas, including the left dorsomedial prefrontal cortex (DMPFC), anterior cingulate cortex (ACC), and bilateral posterior cingulate cortex/precuneus (PCC/PC). It suggests that the DMN plays a role in processing contextually expected information and supports recent evidence that the DMN may
Sex difference in the near-24-hour intrinsic period of the human circadian timing system
Duffy, Jeanne F.; Cain, Sean W.; Chang, Anne-Marie; Phillips, Andrew J. K.; Münch, Mirjam Y.; Gronfier, Claude; Wyatt, James K.; Dijk, Derk-Jan; Wright, Kenneth P.; Czeisler, Charles A.
2011-01-01
The circadian rhythms of melatonin and body temperature are set to an earlier hour in women than in men, even when the women and men maintain nearly identical and consistent bedtimes and wake times. Moreover, women tend to wake up earlier than men and exhibit a greater preference for morning activities than men. Although the neurobiological mechanism underlying this sex difference in circadian alignment is unknown, multiple studies in nonhuman animals have demonstrated a sex difference in cir...
Xiaokui Yue
2014-01-01
Full Text Available A numerical approach for obtaining periodic orbits of satellite relative motion is proposed, based on using the time domain collocation (TDC method to search for the periodic solutions of an exact J2 nonlinear relative model. The initial conditions for periodic relative orbits of the Clohessy-Wiltshire (C-W equations or Tschauner-Hempel (T-H equations can be refined with this approach to generate nearly bounded orbits. With these orbits, a method based on the least-squares principle is then proposed to generate projected closed orbit (PCO, which is a reference for the relative motion control. Numerical simulations reveal that the presented TDC searching scheme is effective and simple, and the projected closed orbit is very fuel saving.
One-dimensional, time dependent simulation of the planetary boundary layer over a 48-hour period
Results of a one-dimensional, time dependent simulation of the planetary boundary layer are given. First, a description of the mathematical model used is given and its approximations are discussed. Then a description of the initial and boundary conditions used for the simulation is given. Results are discussed with respect to their agreement with observed data and their precision. It can be demonstrated that a simulation of the planetary boundary layer is possible with satisfactory precision. The incompleteness of observed data gives, however, problems with their use and thus introduces uncertainties into the simulation. As a consequence, the report tries to point to the inherent limitations of such a simulation. (Auth.)
Nonparametric decomposition of quasi-periodic time series for change-point detection
Artemov, Alexey; Burnaev, Evgeny; Lokot, Andrey
2015-12-01
The paper is concerned with the sequential online change-point detection problem for a dynamical system driven by a quasiperiodic stochastic process. We propose a multicomponent time series model and an effective online decomposition algorithm to approximate the components of the models. Assuming the stationarity of the obtained components, we approach the change-point detection problem on a per-component basis and propose two online change-point detection schemes corresponding to two real-world scenarios. Experimental results for decomposition and detection algorithms for synthesized and real-world datasets are provided to demonstrate the efficiency of our change-point detection framework.
High-order fuzzy time-series based on multi-period adaptation model for forecasting stock markets
Chen, Tai-Liang; Cheng, Ching-Hsue; Teoh, Hia-Jong
2008-02-01
Stock investors usually make their short-term investment decisions according to recent stock information such as the late market news, technical analysis reports, and price fluctuations. To reflect these short-term factors which impact stock price, this paper proposes a comprehensive fuzzy time-series, which factors linear relationships between recent periods of stock prices and fuzzy logical relationships (nonlinear relationships) mined from time-series into forecasting processes. In empirical analysis, the TAIEX (Taiwan Stock Exchange Capitalization Weighted Stock Index) and HSI (Heng Seng Index) are employed as experimental datasets, and four recent fuzzy time-series models, Chen’s (1996), Yu’s (2005), Cheng’s (2006) and Chen’s (2007), are used as comparison models. Besides, to compare with conventional statistic method, the method of least squares is utilized to estimate the auto-regressive models of the testing periods within the databases. From analysis results, the performance comparisons indicate that the multi-period adaptation model, proposed in this paper, can effectively improve the forecasting performance of conventional fuzzy time-series models which only factor fuzzy logical relationships in forecasting processes. From the empirical study, the traditional statistic method and the proposed model both reveal that stock price patterns in the Taiwan stock and Hong Kong stock markets are short-term.
Cover cropping under temperate conditions: influence of growth period and incorporation time
Thomsen, Ingrid Kaag; Hansen, Elly Møller
of the main crop which determined time of their sowing. The reduction in nitrate leaching with Autumn CC was generally about half of the reduction caused by Winter CC. Preliminary results suggest that the decomposability of CC is not highly affected by the developmental stage reached by the CC before......Cover crops (CC) are generally followed by spring sown crops which limits the use of winter cereals in a crop rotation. A change from winter cereals as e.g. winter wheat (Triticum aestivum L.) to a spring sown crop as barley (Hordeum vulgare L.) often results in a reduction in grain yield....... To encourage increased use of CC and to lessen the consequences on choice of main crop new innovative ways of using CC should be considered. This study tested the potential for using CC that could allow for repeated winter wheat growing and still permit CC in breaks between crops. Cruciferous CC (Raphanus...
H.Beir(a)o da Veiga
2006-01-01
The problem of the existence of time-periodic flows in infinite cylindrical pipes in correspondence to any given, time-periodic, total flux, was solved only quite recently in [1]. In this last reference we solved the above problem for flows under the non-slip boundary condition as a corollary of a more general result. Here we want to show that the abstract theorem proved in [1] applies as well to the solutions of the well known slip (or Navier) boundary condition (1.7) or to the mixed boundary condition (1.14). Actually, the argument applies for solutions of many other boundary value problems. This paper is a continuation of reference [1], to which the reader is referred for some notation and results.
Carvalho, Thais; Bacha, Carlos
2011-01-01
This paper aims to analyze the regional impacts of the steel and environmental policies on the structure and location of charcoal production in Brazil during the time period from 1980 to 2007. Both statistic and interpretative analysis of secondary data, organized in tables or graphs, are used, paying a special attention to the similarities and differences among the database. The main findings of the paper are: (1st) even though charcoal is an archaic energy source, it still represents 3% of ...
Huicheng, Yin; Lin, Zhang; Lu, Zhu
2014-01-01
In this paper, we study the large time behavior of the 3-D isentropic compressible Navier-Stokes equation in the partial space-periodic domains, and simultaneously show that the related profile systems can be described by like Navier-Stokes equations with suitable "pressure" functions in lower dimensions. Our proofs are based on the energy methods together with some delicate analysis on the corresponding linearized problems.
FERGANY, Hala A.
2005-01-01
This study treats the probabilistic safety stock n-items inventory system having varying order cost and zero lead-time subject to two linear constraints. The expected total cost is composed of three components: the average purchase cost; the expected order cost and the expected holding cost. The policy variables in this model are the number of periods Nr* and the optimal maximum inventory level Qmr* and the minimum expected total cost. We can obtain the optimal values of these policy variable...
Baluev, Roman V.
2013-01-01
This is a parallelized algorithm performing a decomposition of a noisy time series into a number of sinusoidal components. The algorithm analyses all suspicious periodicities that can be revealed, including the ones that look like an alias or noise at a glance, but later may prove to be a real variation. After selection of the initial candidates, the algorithm performs a complete pass through all their possible combinations and computes the rigorous multifrequency statistical significance for...
Mahanty, M. M.; Mohanty, P. K.; Pattnaik, A. K.; Panda, U. S.; Pradhan, S.; Samal, R. N.
2016-08-01
This paper investigated the hydrodynamics, spatio-temporal variability of temperature/salinity and the residence time of tracer concentrations in a largest brackish water coastal lagoon in Asia, namely the Chilika lagoon, India. An integrated approach combined the measurement and 2D hydrodynamic-advection/dispersion model is used to simulate circulation and temperature/salinity, and estimated the water residence time in lagoon under different forcing mechanisms, such as tide, wind and freshwater discharge during the dry and wet periods. Water circulation inside the lagoon is simulated when wind is included with the tide only forcing during dry period, and freshwater influx is included with the tide and wind forcing during wet period. Under the realistic forcing conditions, the computed temporal variability of water temperature and salinity are well correlated with the measurements in both the periods. The spatial variations of water temperature within the lagoon is influenced by the meteorological conditions, tide and freshwater influx as well as the shallowness of the lagoon, whereas the salinity is spatially controlled by the freshwater influx from the riverine system and seawater intrusion through the tidal inlets. The numerical model results show that in the Chilika lagoon tidal and river influx affect significantly the residence time spatially, and is site specific. The residence time varies from values of 4-5 days in the outer channel (OC) and 132 days at the northern sector (NS) in the main body of lagoon. The current study represents a first attempt to use a combined model approach, which is therefore, a useful tool to support the ecological implication of the lagoon ecosystem.
Hui Fang
2012-01-01
We study a competition system of the growth of two species of plankton with competitive and allelopathic effects on each other on time scales. With the help of Mawhin’s continuation theorem of coincidence degree theory, a set of easily verifiable criteria is obtained for the existence of at least two periodic solutions for this model. Some new existence results are obtained. An example and numerical simulation are given to illustrate the validity of our results.
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.
It is of utmost importance to have a computer code in order to analyze how different parameters (like test duration time) affect the unavailability of safety systems of nuclear. In this context, a study was performed in order to evaluate the model employed by the FRANTIC computer code, which performs detailed calculations on the contribution to the system unavailability originated by hardware failures, component tests and repairs, aiming at considering the influence of different test schemes on the system unavailability. It was shown, by means of the results attained that the numerical model used by the FRANTIC code and the analytical model proposed by APOSTOLAKIS and CHU (4) give unavailability values much similar when the component tests are supposed to be perfect. When a test is supposed to be imperfect (that is, when it may induce a test is supposed to be imperfect (that is, when it may induce a failure on the component being tested), the analytical model presents more conservative results. (author)
Salamalikis, V.; Argiriou, A. A.; Dotsika, E.
2016-03-01
In this paper the periodic patterns of the isotopic composition of precipitation (δ18O) for 22 stations located around Central Europe are investigated through sinusoidal models and wavelet analysis over a 23 years period (1980/01-2002/12). The seasonal distribution of δ18O follows the temporal variability of air temperature providing seasonal amplitudes ranging from 0.94‰ to 4.47‰; the monthly isotopic maximum is observed in July. The isotopic amplitude reflects the geographical dependencies of the isotopic composition of precipitation providing higher values when moving inland. In order to describe the dominant oscillation modes included in δ18O time series, the Morlet Continuous Wavelet Transform is evaluated. The main periodicity is represented at 12-months (annual periodicity) where the wavelet power is mainly concentrated. Stations (i.e. Cuxhaven, Trier, etc.) with limited seasonal isotopic effect provide sparse wavelet power areas at the annual periodicity mode explaining the fact that precipitation has a complex isotopic fingerprint that cannot be examined solely by the seasonality effect. Since temperature is the main contributor of the isotopic variability in mid-latitudes, the isotope-temperature effect is also investigated. The isotope-temperature slope ranges from 0.11‰/°C to 0.47‰/°C with steeper values observed at the southernmost stations of the study area. Bivariate wavelet analysis is applied in order to determine the correlation and the slope of the δ18O - temperature relationship over the time-frequency plane. High coherencies are detected at the annual periodicity mode. The time-frequency slope is calculated at the annual periodicity mode ranging from 0.45‰/°C to 0.83‰/°C with higher values at stations that show a more distinguishable seasonal isotopic behavior. Generally the slope fluctuates around a mean value but in certain cases (sites with low seasonal effect) abrupt slope changes are derived and the slope becomes
A charged particle in a homogeneous magnetic field accelerated by a time-periodic Aharonov-Bohm flux
We consider a nonrelativistic quantum charged particle moving on a plane under the influence of a uniform magnetic field and driven by a periodically time-dependent Aharonov-Bohm flux. We observe an acceleration effect in the case when the Aharonov-Bohm flux depends on time as a sinusoidal function whose frequency is in resonance with the cyclotron frequency. In particular, the energy of the particle increases linearly for large times. An explicit formula for the acceleration rate is derived with the aid of the quantum averaging method, and then it is checked against a numerical solution and a very good agreement is found. - Highlights: → A nonrelativistic quantum charged particle on a plane. → A homogeneous magnetic field and a periodically time-dependent Aharonov-Bohm flux. → The quantum averaging method applied to a time-dependent system. → A resonance of the AB flux with the cyclotron frequency. → An acceleration with linearly increasing energy; a formula for the acceleration rate.
The creation of the rapid and sensitive system for the determination of the Alpha-radioactivity in the Environmental samples has been determined as the main goal of the Research Contract No. 7200RO/RB. As a result of the first stage of the research accomplished in the year 1993, the prototype of the system based on the combination of the laser photoionization mass spectrometry and many-channel alpha-spectrometer has been built and tested. To improve the sensitivity it was proposed to add one more stage to the laser photoionization mass-spectrometer. To develop the high position sensitivity of the system it was proposed to include into the alpha-radiometer SI strip-detector with submicron position sensitivity. Hardware and software for the laser-semiconductor monitoring system of alpha-radionuclides in the environment have been further developed and tested in frames of the IAEA Research Contract No. 7200/R1/RB. Optimization of the sample evaporation with one more stage of photoionization has been successfully performed in the laser photoionization mass-spectrometer. The automatization of the measurement procedure is under way by means of the IBM PC-386 and specially designed electronic units. The evaluated sensitivity of the new set-up is in the range of 1.0 Bq/kg. A bulk measurement of the alpha-radioactivity concentration in soil samples from the Chernobyl region (100 km) have been performed by means of thick samples method and built under this contract alpha-radiometer with large area SI semiconductor detectors. The lowest detectable level was in the range 100 Bq/kg without any radiochemical separation. Comparison with the data obtained for the same probes by means of the thin sample (with radiochemical separation) has shown higher Pu-concentration values obtained by means of the thick samples. For the first time the Sl-strip-detector with 128 channels has been applied for the alpha-radiometry purposes. Different read-out electronics (including the most
Liang, Xing; Jiang, Jifa
The asymptotic behavior of discrete type-K monotone dynamical systems and reaction-diffusion equations is investigated. The studying content includes the index theory for fixed points, permanence, global stability, convergence everywhere and coexistence. It is shown that the system has a globally asymptotically stable fixed point if every fixed point is locally asymptotically stable with respect to the face it belongs to and at this point the principal eigenvalue of the diagonal partial derivative about any component not belonging to the face is not one. A nice result presented is the sufficient and necessary conditions for the system to have a globally asymptotically stable positive fixed point. It can be used to establish the sufficient conditions for the system to persist uniformly and the convergent result for all orbits. Applications are made to time-periodic Lotka-Volterra systems with diffusion, and sufficient conditions for such systems to have a unique positive periodic solution attracting all positive initial value functions are given. For more general time-periodic type-K monotone reaction-diffusion systems with spatial homogeneity, a simple condition is given to guarantee the convergence of all positive solutions.
Costa-Castelló, R.; Olm, J. M.; Ramos, G. A.
2011-07-01
This article analyses stability and performance features of different design schemes for digital repetitive control systems subject to references/disturbances that exhibit non-uniform frequency. Aiming at maintaining a constant value for the ratio T p /T s , T p being the period of the reference/disturbance signal and T s being the sampling period, two approaches are proposed. The first one deals with the real-time adaptation of T s to the actual changes of T p ; stability is studied by means of an LMI gridding method and also using robust control techniques. The second one propounds the introduction of an additional compensator that annihilates the effect of the time-varying sampling in the closed-loop system and forces its behaviour to coincide with that of an a priori selected nominal sampling period; the internal stability of the compensator-plant subsystem is checked by means of LMI gridding. The theoretical results are experimentally tested and compared through a mechatronic plant model.
Masahide Usami
Full Text Available BACKGROUND/AIM: The questionnaire-children with difficulties (QCD is a parent-assessed questionnaire designed to evaluate a child's difficulties in functioning during specific time periods of the day. In this study, the QCD was applied to determine the time periods of the day that are concerning for the parents of children with attention deficit hyperactivity disorder (ADHD. The results were compared with those for a community sample. METHODS: Elementary and junior high school students with ADHD (243 boys, 55 girls and a community sample of children (518 boys, 618 girls were enrolled in this study. Their behaviors were assessed by the QCD, the ADHD-rating scale (ADHD-RS, and the Oppositional Defiant Behavior Inventory (ODBI. The effects of gender (boy/girl and diagnosis (ADHD/community sample on the total QCD score were analyzed across each school grade (elementary/junior high school. Correlation coefficients between QCD and ADHD-RS/ODBI scores were analyzed. RESULTS: The QCD score for the ADHD group was significantly lower than that for the community sample (P 0.41, P 0.40, P < 0.001. CONCLUSIONS: Parents reported that children with ADHD faced greater difficulties in completing basic daily activities compared with the community controls, particularly in the evening. Furthermore, these difficulties were related to the severity of ADHD symptoms. The parents' perceptions depended on the gender, ADHD and oppositional symptoms, and the time period of the day. This study determined that children with ADHD face greater difficulties in daily functioning compared with community sample children, that these difficulties are time-dependent, and that these difficulties were particularly experienced in the evening.
Li, Hongfei; Jiang, Haijun; Hu, Cheng
2016-03-01
In this paper, we investigate a class of memristor-based BAM neural networks with time-varying delays. Under the framework of Filippov solutions, boundedness and ultimate boundedness of solutions of memristor-based BAM neural networks are guaranteed by Chain rule and inequalities technique. Moreover, a new method involving Yoshizawa-like theorem is favorably employed to acquire the existence of periodic solution. By applying the theory of set-valued maps and functional differential inclusions, an available Lyapunov functional and some new testable algebraic criteria are derived for ensuring the uniqueness and global exponential stability of periodic solution of memristor-based BAM neural networks. The obtained results expand and complement some previous work on memristor-based BAM neural networks. Finally, a numerical example is provided to show the applicability and effectiveness of our theoretical results. PMID:26752438
Marti, Clelia Luisa; Imberger, Jörg; Garibaldi, Letizia; Leoni, Barbara
2016-03-01
A combination of field observations and 3-D hydrodynamic simulations were used to identify the phytoplankton species and to estimate the various time scales of the dominant physical and biological processes in Lake Iseo, a deep subalpine lake located in northern Italy, during a stratified period (July 2010). By ordering the rate processes time scales, we derive a phytoplankton patch categorization and growth interpretation that provides a general framework for the spatial distribution of phytoplankton concentration in Lake Iseo and illuminates the characteristics of their ecological niches. The results show that the diurnal surface layer was well mixed, received strong diurnal radiation, had low phosphorus concentrations and the phytoplankton biomass was sustained by the green alga Sphaerocystis schroeterii. The vertical mixing time scales were much shorter than horizontal mixing time scales causing a depth-uniform chlorophyll a concentration. The horizontal patch scale was determined by horizontal dispersion balancing the phytoplankton growth time scale, dictating the success of the observed green algae. The strongly stratified nutrient-rich metalimnion had mild light conditions and Diatoma elongatum and Planktothrix rubescens made up the largest proportions of the total phytoplankton biomass at the intermediate and deeper metalimnetic layers. The vertical transport time scales were much shorter than horizontal transport and vertical dispersion leading to growth niche for the observed phytoplankton. The study showed that time-scale hierarchy mandates the essential phytoplankton attributes or traits for success in a particular section of the water column and/or water body.
Willis, A P; Willis, Ashley P.; Gubbins, David
2004-01-01
Choosing a simple class of flows, with characteristics that may be present in the Earth's core, we study the ability to generate a magnetic field when the flow is permitted to oscillate periodically in time. The flow characteristics are parameterised by D, representing a differential rotation, M, a meridional circulation, and C, a component characterising convective rolls. Dynamo action is sensitive to these flow parameters and fails spectacularly for much of the parameter space where magnetic flux is concentrated into small regions. Oscillations of the flow are introduced by varying the flow parameters in time, defining a closed orbit in the space (D,M). Time-dependence appears to smooth out flux concentrations, often enhancing dynamo action. Dynamo action can be impaired, however, when flux concentrations of opposite signs occur close together as smoothing destroys the flux by cancellation. It is possible to produce geomagnetic-type reversals by making the orbit stray into a region where the steady flows ge...
Haraguchi, Atsushi; Aoki, Natsumi; Ohtsu, Teiji; Ikeda, Yuko; Tahara, Yu; Shibata, Shigenobu
2014-10-01
Free feeding (FF) with a high fat diet (HFD) causes excessive body weight gain, whereas restricted feeding (RF) with a HFD attenuates body weight gain. The effects of timing of feeding with a HFD (day vs. night) and feeding duration on energy homeostasis have not yet been investigated. In this study, we fed mice a HFD or a normal diet (ND) twice a day, during their active and inactive periods, on a schedule. The amount of food was regulated by feeding duration (2, 4 or 8 h). First, we investigated the effects of 4-h RF during active-inactive periods (ND-ND, HFD-HFD, ND-HFD or HFD-ND). Among all the 4-h RF groups, mice consumed almost the same amount of calories as those in the FF[ND] group, even those fed a HFD. Body weight and visceral fat in these three groups were lower than that in the FF[HFD] group. Second, we investigated the effects of RF duration. Body weight and visceral fat were higher in the 8-h groups than in the 4-h groups. Body weight and visceral fat were higher in the 2-h groups than in the 4-h groups even though the 2-h groups had less food. Third, we investigated the effects of eating a HFD during the inactive period, when RF duration was extended (2, 6 or 12 h). Mice were fed with a HFD during the inactive period for 2 h and fed with a ND during the active period for 2, 6 or 12 h. Body weight and visceral fat in these mice were comparable to those in the FF[ND] mice. The results of our first set of experiments suggest that 4-h RF was an adequate feeding duration to control the effect of a HFD on obesity. The results of our second set of experiments suggest 2-h RF (such as speed-eating) and 8-h RF, representative of eating disorders, are unhealthy feeding patterns related to obesity. The results of our third set of experiments suggest that eating a HFD for a short period during the night does not affect body weight and visceral fat. Taken together, these results indicate that consideration to feeding with a HFD during the inactive period and
In recent years there has been growing concern over the stimulating effects of very low-dose X -rays. Our laboratory had observed that zebrafish irradiated with low-dose X-rays tended to emerge earlier than sham controls. This observation led us to quantitatively examine the effects of low-dose X irradiation on a series of stages of development in the zebrafish. The embryos were fertilized simultaneously in vitro and incubated at an optimal temperature without crowding. Following exposure of the cleavage period (1.5 h after fertilization) to 0.025-Gy X-rays, the duration to hatching was slightly shorter than that of the sham controls. This tendency was increased when the X-ray exposure occurred during the blastula period (3.5 h). In these embryos, the duration to hatching decreased significantly by an average of 6 h sooner than for sham controls. No differences in duration to hatching were seen when irradiation was given during either the zygote period (45 min) or the segmentation period (12 h). On the contrary, upon exposure to 0.5-Gy X-rays during the blastula period, the duration to hatching increased significantly relative to that of sham controls. These results suggest that the radiation-induced early hatching effect is observed for low doses of X-rays
Naglaa H. El-Sodany
2011-01-01
Problem statement: This study treats the probabilistic safety stock n-items inventory system having varying holding cost and zero lead-time subject to linear constraint. Approach: The expected total cost is composed of three components: the average purchase cost; the expected order cost and the expected holding cost. Results: The policy variables for this model are the number of periods N*r and the optimal maximum inventory level Q*mr and the minimum expected total cost. Conclusion/Recom...
Gerez, Sabih H.; Heemstra de Groot, Sonia M.; Herrmann, Otto E.
1992-01-01
Rate-optimal scheduling of iterative data-flow graphs requires the computation of the iteration period bound. According to the formal definition, the total computational delay in each directed loop in the graph has to be calculated in order to determine that bound. As the number of loops cannot be expressed as a polynomial function of the number of modes in the graph, this definition cannot be the basis of an efficient algorithm. A polynomial-time algorithm for the computation of the iteratio...
D. Carpentier
2015-07-01
Full Text Available We present mathematical details of the construction of a topological invariant for periodically driven two-dimensional lattice systems with time-reversal symmetry and quasienergy gaps, which was proposed recently by some of us. The invariant is represented by a gap-dependent Z2-valued index that is simply related to the Kane–Mele invariants of quasienergy bands but contains an extra information. As a byproduct, we prove new expressions for the two-dimensional Kane–Mele invariant relating the latter to Wess–Zumino amplitudes and the boundary gauge anomaly.
Miqdam Tariq Chaichan
2014-12-01
Full Text Available Heavy-duty diesel vehicle idling consumes fossil fuel and reduces atmospheric quality at idle period, but its restriction cannot simply be proscribed. A comprehensive tailpipe emissions database to describe idling impacts is not yet available. This paper presents a substantial data set that incorporates results from DI multi-cylinders Fiat diesel engine. Idle emissions of CO, hydrocarbon (HC, oxides of nitrogen (NOx, smoke opacity, carbon dioxide (CO2 and noise have been reported, when three EGR ratios (10, 20 and 30% were added to suction manifold. CO2 concentrations increased with increasing idle time and engine idle speed, but it didn’t show clear effect for IT advancing. CO concentrations increased for all the studied tests with adding EGR. HC concentration increased with idle time advance, but it reduced with increasing idle speed and advancing engine IT. NOx concentrations reduced with adding EGR for all the tested variables. NOx increased with increasing idle time, engine speed and advancing IT. Smoke opacity increased with increasing idle time and retarding IT. Using EGR increased opacity for all tested cases. EGR addition reduced engine noise for all tested cases. Engine noise increased with increasing idle time and retarding IT.
This work analyzes numerically the effects of delay time τ and cross-correlation strength between noises λ on the phenomena of noise enhanced stability (NES) and resonant activation (RA) in a periodically modulated bistable system. The simulation results indicate that: (i) multiplicative noise can produce the NES effect only for the larger λ, while additive noise always induces the NES effect; (ii) for the NES phenomenon induced by additive noise, there is a characteristic value of τ, below which the increasing of τ enhances it and above which the effect of τ reverses; however, the increasing of τ can only enhance the NES effect induced by multiplicative noise; (iii) increasing λ weakens the NES effect induced by additive noise and strengthens that induced by multiplicative noise; and (iv) the RA effect becomes more and more pronounced while the RA minimum of the mean first-passage time increases with the increase of λ or τ. (paper)
Marușa Beca
2015-06-01
Full Text Available In this article, we studied the relationship between macroeconomic factors and the observed corporate births for the Romanian economy through the Autoregressive Distributed Lags Model (ADL. We performed a time series analysis that uses monthly data for the period January 2008 – December 2013 in order to establish the impact of the fiscal and monetary policy adopted by the Romanian government in times of economic crisis on the firms’ demography. The corporate birth rate is an endogenous variable in a linear function model with five exogenous macroeconomic variables such as the CPI, the loans ratio to GDP, the FDI, the long term interest rate, tax rate to GDP and the lags of the dependent variable. The main finding is that the variance of the corporate birth rate variable is negatively correlated with the variances of CPI in the current month and the interest rate two months lagged. We also determined that the variance of the dependent variable was positively correlated with the variances of the loans rate two months lagged, tax rate four months ago and FDI two months lagged and FDI in the current period.
The aim of this study was to study trends in bacterial spectrum and susceptibility patterns of pathogens in adult febrile neutropenic patients during two time periods. We retrospectively reviewed the medical records of 379 adult oncology patients admitted with chemotherapy induced febrile neutropenia at our institute during years 2003 and 2006. A total of 151 organisms were isolated during the two calendar years. Gram negative bacteria accounted for 57.6% of organisms, while gram positive organisms accounted for 42.3% of the total isolates. The most common organisms were: Escherichia coli (23.1%), Staphylococcus epidermidis (13.9%), Pseudomonas aeruginosa (12.5%) and Staphylococcus aureus (7.9%). The number of gram positive isolates showed an increase from 35% in 2003 to 47.2% in 2006 (p=0.13). During each calendar year, Staphylococcus epidermidis and Staphylococcus aureus were 100% susceptible to vancomycin and 33% strains of Staphylococcus aureus were methicillin resistant. Escherichia coli and Pseudomonas aeruginosa strains were highly sensitive to piperacillin/tazobactam and amikacin during both time periods. Resistance of Pseudomonas aeruginosa strains to ciprofloxacin increased from 0% in 2003 to 50% in 2006 (p=0.03). Gram negative organisms are the predominant organisms in adult febrile neutropenic patients at our institute. Initial empirical therapy with piperacillin/tazobactam seems appropriate to cover most gram negative pathogens while vancomycin to be added for suspected gram positive infections. During the two calendar years resistance of Pseudomonas aeruginosa strains to ciprofloxacin has significantly increased. (author)
Performance of medical radiographic X-ray systems in Greece for the time period 1998-2004.
Economides, S; Hourdakis, C J; Kalivas, N; Kalathaki, M; Simantirakis, G; Tritakis, P; Manousaridis, G; Vogiatzi, S; Kipouros, P; Boziari, A; Kamenopoulou, V
2007-12-01
This study presents the results of the on-site inspections performed by the Greek Atomic Energy Commission (GAEC) on conventional X-ray systems, both in public and private medical radiology departments. A part of the inspection concerns the assessment of important radiographic parameters obtained according to a specified quality control protocol and the comparison of the measured parameter values with the corresponding acceptance limits. A total number of 1011 radiographic systems were inspected by the GAEC during the period 1998-2004, with 63.4% of them being privately owned. Analysis of 8 different operational parameters is carried out providing information on the overall performance, as well as on each parameter of the inspected X-ray systems. Tube voltage reproducibility values show the highest percentage of acceptability (98.9%, 99.5% for private and public owned radiographic systems respectively), while linearity of radiation output for private systems (72.5%) and time accuracy for public ones (72.7%) show the worst results. The comparison of the results for the private sector to those of a similar study carried out during the period 1995-1997 indicates a substantial improvement in X-ray systems performance. Higher level of improvement shows exposure time accuracy (12.2% percentile increase) and linearity of radiation output (12.5% percentile increase). Nevertheless, the situation can be further optimized if maintenance and quality control of the radiographic systems are carried out on a more regular basis. PMID:18023226
Fisher, Aaron J; Reeves, Jonathan W; Chi, Cyrus
2016-07-01
Expanding on recently published methods, the current study presents an approach to estimating the dynamic, regulatory effect of the parasympathetic nervous system on heart period on a moment-to-moment basis. We estimated second-to-second variation in respiratory sinus arrhythmia (RSA) in order to estimate the contemporaneous and time-lagged relationships among RSA, interbeat interval (IBI), and respiration rate via vector autoregression. Moreover, we modeled these relationships at lags of 1 s to 10 s, in order to evaluate the optimal latency for estimating dynamic RSA effects. The IBI (t) on RSA (t-n) regression parameter was extracted from individual models as an operationalization of the regulatory effect of RSA on IBI-referred to as dynamic RSA (dRSA). Dynamic RSA positively correlated with standard averages of heart rate and negatively correlated with standard averages of RSA. We propose that dRSA reflects the active downregulation of heart period by the parasympathetic nervous system and thus represents a novel metric that provides incremental validity in the measurement of autonomic cardiac control-specifically, a method by which parasympathetic regulatory effects can be measured in process. PMID:27045609
Garde, A; Giraldo, B F; Jané, R; Latshang, T D; Turk, A J; Hess, T; Bosch, M M; Barthelmes, D; Merz, T M; Hefti, J Pichler; Schoch, O D; Bloch, K E
2015-08-01
This work investigates the performance of cardiorespiratory analysis detecting periodic breathing (PB) in chest wall recordings in mountaineers climbing to extreme altitude. The breathing patterns of 34 mountaineers were monitored unobtrusively by inductance plethysmography, ECG and pulse oximetry using a portable recorder during climbs at altitudes between 4497 and 7546 m on Mt. Muztagh Ata. The minute ventilation (VE) and heart rate (HR) signals were studied, to identify visually scored PB, applying time-varying spectral, coherence and entropy analysis. In 411 climbing periods, 30-120 min in duration, high values of mean power (MP(VE)) and slope (MSlope(VE)) of the modulation frequency band of VE, accurately identified PB, with an area under the ROC curve of 88 and 89%, respectively. Prolonged stay at altitude was associated with an increase in PB. During PB episodes, higher peak power of ventilatory (MP(VE)) and cardiac (MP(LF)(HR) ) oscillations and cardiorespiratory coherence (MP(LF)(Coher)), but reduced ventilation entropy (SampEn(VE)), was observed. Therefore, the characterization of cardiorespiratory dynamics by the analysis of VE and HR signals accurately identifies PB and effects of altitude acclimatization, providing promising tools for investigating physiologic effects of environmental exposures and diseases. PMID:25820153
Ambrose, David M.; Wilkening, Jon
2008-12-11
We classify all bifurcations from traveling waves to non-trivial time-periodic solutions of the Benjamin-Ono equation that are predicted by linearization. We use a spectrally accurate numerical continuation method to study several paths of non-trivial solutions beyond the realm of linear theory. These paths are found to either re-connect with a different traveling wave or to blow up. In the latter case, as the bifurcation parameter approaches a critical value, the amplitude of the initial condition grows without bound and the period approaches zero. We propose a conjecture that gives the mapping from one bifurcation to its counterpart on the other side of the path of non-trivial solutions. By experimentation with data fitting, we identify the form of the exact solutions on the path connecting two traveling waves, which represents the Fourier coefficients of the solution as power sums of a finite number of particle positions whose elementary symmetric functions execute simple orbits in the complex plane (circles or epicycles). We then solve a system of algebraic equations to express the unknown constants in the new representation in terms of the mean, a spatial phase, a temporal phase, four integers (enumerating the bifurcation at each end of the path) and one additional bifurcation parameter. We also find examples of interior bifurcations from these paths of already non-trivial solutions, but we do not attempt to analyze their algebraic structure.
The stochastic resonance (SR) phenomenon induced by a multiplicative periodic signal in a bistable system with cross-correlated noises and time delay is studied. Two cases have been considered: the case of a system with no delay and the case of a system with time-delayed feedback. The expressions for the signal-to-noise ratio (SNR) are derived, for both cases. The effects of the cross-correlated noise intensity (λ) and the delay time (τ) on the SNR are discussed. It is found that the existence of a maximum in the SNR is the identifying characteristic of the SR phenomenon. In contrast with the case for the SR induced by an additive signal, here both λ and τ have critical values in SR when the SNR as a function of the noise intensities, i.e., λ (or τ), suppresses the SR for λ (or τ) below the critical value while it enhances the SR for λ (or τ) above the critical value. τ suppresses the SR in the SNR as a function of λ while it enhances the SR in the SNR as a function of the noise intensities. The SNR is not only dependent on λ, τ and the noise intensities, but also on the initial condition of the system
Vesna Vučinić-Nešković
2016-02-01
Full Text Available This paper deals with the question of how the state policies during the later Maoist period, from the beginning of the Great Leap Forward (1958 to the introduction of the Modernization Reforms (1978, affected the organization of time in the Chinese countryside. After abandoning the initial Soviet model of modernization, based on the exclusive strengthening of heavy industry, the China’s leadership developed a strategy of parallel development of agriculture and industry, wherein the former would additionally support the modernization of the latter. The study is focused on the ways the longer term state plans and shorter term economic, social and ideological policies and campaigns jointly influenced the rhythms of life of Chinese peasants. The domains in which these influences became visible were: (1 the intensification of agricultural practices, (2 the introducing of the small-scale industry, and (3 the politicizing of the spare time. In the analysis the characteristic rhythms of work and rest within the daily, weekly, seasonal, and annual time spans are followed in detail.
Is there long-range memory in solar activity on time scales shorter than the sunspot period?
Rypdal, Martin
2011-01-01
The sunspot number (SSN), the total solar irradiance (TSI), a TSI reconstruction, and the solar flare index (SFI), are analyzed for long-range persistence (LRP). Standard Hurst analysis yields $H \\approx 0.9$, which suggests strong LRP. However, solar activity time series are non-stationary due to the almost periodic 11 year smooth component, and the analysis does not give the correct $H$ for the stochastic component. Better estimates are obtained by detrended fluctuations analysis (DFA), but estimates are biased and errors are large due to the short time records. These time series can be modeled as a stochastic process of the form $x(t)=y(t)+\\sigma \\sqrt{y(t)}\\, w_H(t)$, where $y(t)$ is the smooth component, and $w_H(t) $ is a stationary fractional noise with Hurst exponent $H$. From ensembles of numerical solutions to the stochastic model, and application of Bayes' theorem, we can obtain bias and error bars on $H$ and also a test of the hypothesis that a process is uncorrelated ($H=1/2$). The conclusions fr...
Time delays in quasi-periodic pulsations observed during the X2.2 solar flare on 2011 February 15
Dolla, L; Seaton, D B; Van Doorsselaere, T; Dominique, M; Berghmans, D; Cabanas, C; De Groof, A; Schmutz, W; Verdini, A; West, M J; Zender, J; Zhukov, A N
2012-01-01
We report observations of quasi-periodic pulsations (QPPs) during the X2.2 flare of 2011 February 15, observed simultaneously in several wavebands. We focus on fluctuations on time scale 1-30 s and find different time lags between different wavebands. During the impulsive phase, the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) channels in the range 25-100 keV lead all the other channels. They are followed by the Nobeyama RadioPolarimeters at 9 and 17 GHz and the Extreme Ultra-Violet (EUV) channels of the Euv SpectroPhotometer (ESP) onboard the Solar Dynamic Observatory (SDO). The Zirconium and Aluminum filter channels of the Large Yield Radiometer (LYRA) onboard the Project for On-Board Autonomy (PROBA2) satellite and the SXR channel of ESP follow. The largest lags occur in observations from the Geostationary Operational Environmental Satellite (GOES), where the channel at 1-8 {\\AA} leads the 0.5-4 {\\AA} channel by several seconds. The time lags between the first and last channels is up to 9 ...
We investigate the singularity structure analysis of the higher-dimensional time-gated Manakov system referring to the (2+1)-dimensional coupled nonlinear Schroedinger (CNLS) equations, and we show that these equations are Painleve-integrable. By means of the Weiss et al.'s methodology, we show the arbitrariness of the expansion coefficients and the consistency of the truncation corresponding to a special Baecklund transformation (BT) of these CNLS equations. In the wake of such transformation, following the Hirota's formalism, we derive a one-soliton solution. Besides, by using the Zakharov-Shabat (ZS) scheme which provides a general Lax-representation of an evolution system, we show that the (2+1)-dimensional CNLS system under interests is completely integrable. Furthermore, using the arbitrariness of the above coefficients, we unearth and investigate a typical spectrum of periodic coherent structures while depicting elastic interactions amongst such patterns. (author)
Hardik N. Soni
2015-03-01
Full Text Available In this paper, an attempt has been made to develop a periodic review inventory model by considering lead-time and the backorder rate as control variables in fuzzy stochastic environment. Without loss of generality, we have assumed that all the observed values of the fuzzy random variable, representing the demand as triangular fuzzy numbers. The variance of fuzzy random demand is taken into consideration to give due attention to every fuzzy observations. The protection interval demand has also been assumed to be fuzzy stochastic. The expected shortages are calculated by using credibility criterion. For the proposed model, we provide a solution procedure incorporating numerical technique viz. Scan and zoom method to determine an optimal policy. A numerical example is taken up to illustrate the solution procedure and sensitivity analysis of the optimal solution with respect to the key parameters of the system is carried out.
mostafa gholamrezaii rahimi
2015-09-01
Full Text Available Production planning is one of the most important tasks of production and operations management and decides to determine the optimum amount of production, labor and inventory levels for each period of planning horizon with regard to productive resources and limits. This research presents a multi-product and multi-objective model of production planning with fuzzy parameters and soft constraints regarding the time value of money, inventory level, labor, capacity of machines and warehouse space. The proposed model attempts to maximize profit of the sale and minimize carrying and backordering costs and changes in labor levels. Case study conducted in the aluminum factory, shows the performance of this model comparing the current situation.
无
2001-01-01
The present study investigated the possible changes in the mixis potential of rotifer resting eggs produced by a single stock of Brachionus plicatilis and collected and preserved annually from 1985-1998. Several clones derived from each batch of resting eggs were cultured under the same conditions for 21 days. The percentage of clones appearing resting eggs and the average yield of resting eggs produced from each clone were recorded and statistically analyzed to find the differences between the mixis potential of those resting egg batches. Results showed that different batches of resting eggs had different mictic levels among their descendent clones; but no regular relationship was found between the mixis potential of resting eggs and their collection times/preservation periods. Several internal and external factors that might affect the mixis potential of resting eggs were discussed.
Antonio Lobo
2005-06-01
Full Text Available Background: Comparative studies of dementia in different time periods are quite limited in the international literature, but might be useful to test environmental hypotheses. The aim of this study is to compare the prevalence of "organic brain syndrome", as a measure of dementia, in the elderly living in the same community in two different time periods and using the same methods. Methods: Representative samples of the elderly in the Zaragoza Study or ZARADEMP 0 (n= 1,080, completed the past decade, and now in Wave I of the ZARADEMP Project or ZARADEMP I (n= 4,803 were interviewed. The Geriatric Mental State (GMS was the main case-finding instrument and the results were analysed using the AGECAT diagnostic package to generate diagnoses. Results: Adjusted, total prevalence of "organic brain syndrome" in individuals aged 65 years and older has not varied from the previous decade. It was 8.4% in ZARADEMP I , and 7.4% in ZARADEMP 0 (prevalence ratio, PR = 0.83; CI 0.65-1.07. Adjusted prevalence among men was lower in ZARADEMP I (3.6% when compared to ZARADEMP 0 (5.5%, although the differences do not reach statistically significance (PR= 0.65; CI 0.41-1.05. However, in support of the working hypothesis, the differences were more marked, and we consider they reach statistically significant proportions in the age group 80-84 years. Conclusions: The prevalence of "organic brain syndrome" has not increased from the previous decade. On the contrary, the prevalence tends to be lower in men, and the differences reach stastistical significance in the age group 80-84 years. New analysis using diagnostic criteria of dementia in the same sample are required to confirm these findings.
Lucca Fabris, Andrea; Young, Christopher; Cappelli, Mark
2014-10-01
We track the evolution of the Xe I 6 s '[ 1 / 2 ] 1 - 6 p '[ 3 / 2 ] 2 (834.68 nm air) transition lineshape in a plasma discharge oscillating at 60 Hz. Two time-synchronized laser induced fluorescence techniques based on phase sensitive detection of the fluorescence signal are demonstrated, yielding consistent results. One approach used previously involves a sample-and-hold procedure that collects fluorescence signal at a particular phase in the oscillation period and holds the average value until the following sample. The second method is based on fast switching of the fluorescence signal; only the signal collected inside the acquisition gate is sent to a lock-in amplifier for processing. Both methods rely on modulating the exciting laser beam and the latter permits operation at a much higher frequency range with reduced spectral noise density. The maximum observed peak fluorescence intensity occurs at low discharge currents, although the peak intensity drops to zero at zero discharge current. The peak intensity also decreases at the discharge current maximum. Time-varying properties of the xenon neutrals are extracted from a lineshape analysis. This work is sponsored by the U.S. Air Force Office of Scientific Research with Dr. Mitat Birkan as program manager. CVY acknowledges support from the DOE NNSA Stewardship Science Graduate Fellowship under Contract DE-FC52-08NA28752.
Coward, Adrian V.; Papageorgiou, Demetrios T.; Smyrlis, Yiorgos S.
1994-01-01
In this paper the nonlinear stability of two-phase core-annular flow in a pipe is examined when the acting pressure gradient is modulated by time harmonic oscillations and viscosity stratification and interfacial tension is present. An exact solution of the Navier-Stokes equations is used as the background state to develop an asymptotic theory valid for thin annular layers, which leads to a novel nonlinear evolution describing the spatio-temporal evolution of the interface. The evolution equation is an extension of the equation found for constant pressure gradients and generalizes the Kuramoto-Sivashinsky equation with dispersive effects found by Papageorgiou, Maldarelli & Rumschitzki, Phys. Fluids A 2(3), 1990, pp. 340-352, to a similar system with time periodic coefficients. The distinct regimes of slow and moderate flow are considered and the corresponding evolution is derived. Certain solutions are described analytically in the neighborhood of the first bifurcation point by use of multiple scales asymptotics. Extensive numerical experiments, using dynamical systems ideas, are carried out in order to evaluate the effect of the oscillatory pressure gradient on the solutions in the presence of a constant pressure gradient.
AROME-WMED, a real-time mesoscale model designed for the HyMeX special observation periods
Fourrié, N.; Bresson, É.; Nuret, M.; Jany, C.; Brousseau, P.; Doerenbecher, A.; Kreitz, M.; Nuissier, O.; Sevault, E.; Bénichou, H.; Amodei, M.; Pouponneau, F.
2015-07-01
During autumn 2012 and winter 2013, two special observation periods (SOPs) of the HYdrological cycle in the Mediterranean EXperiment (HyMeX) took place. For the preparatory studies and to support the instrument deployment during the field campaign, a dedicated version of the operational convective-scale Application of Research to Operations at Mesoscale (AROME)-France model was developed: the AROME-WMED (West Mediterranean Sea) model. It covers the western Mediterranean basin with a 48 h forecast range. It provided real-time analyses and forecasts which were sent daily to the HyMeX operational centre to forecast high-precipitation events and to help decision makers on the deployment of meteorological instruments. This paper presents the main features of this numerical weather prediction system in terms of data assimilation and forecast. Some specific data of the HyMeX SOP were assimilated in real time. The forecast skill of AROME-WMED is then assessed with objective scores and compared to the operational AROME-France model, for both autumn 2012 (05 September to 06 November 2012) and winter 2013 (01 February to 15 March 2013) SOPs. The overall performance of AROME-WMED is good for the first HyMeX special observation period (SOP1) (i.e. mean 2 m temperature root mean square error (RMSE) of 1.7 °C and mean 2 m relative humidity RMSE of 10 % for the 0-30 h forecast ranges) and similar to those of AROME-France for the 0-30 h common forecast range (maximal absolute difference of 2 m temperature RMSE of 0.2 °C and 0.21 % for the 2 m relative humidity); conversely, for the 24-48 h forecast range it is less accurate (relative loss between 10 and 12 % in 2 m temperature and relative humidity RMSE, and equitable threat score (ETS) for 24 h accumulated rainfall), but it remains useful for scheduling observation deployment. The characteristics of parameters, such as precipitation, temperature or humidity, are illustrated by one heavy precipitation case study that occurred
Wang Fengyan [College of Science, Jimei University, Xiamen Fujian 361021 (China)]. E-mail: wangfy68@163.com; Zeng Guangzhao [Department of Mathematics, ShaoGuan University, ShaoGuan, GuangDong 512005 (China)]. E-mail: guangzhaoz@sgu.edu.cn
2007-05-15
In this paper, we introduce and study a Lotka-Volterra predator-prey system with impulsive ratio-harvesting the prey and time delays. By using Floquet theory and small amplitude perturbation skills, we discuss the boundary periodic solutions for predator-prey system under periodic pulsed conditions. The stability analysis of the boundary periodic solution yields an invasion threshold of the predator. Further, by use of the coincidence degree theorem and its related continuous theorem we prove the existence of the positive periodic solutions of the system when the value of the coefficient is large than the threshold. Finally, by comparing bifurcation diagrams with different bifurcation parameters, we show that the impulsive effect and the time delays bring to the system to be more complex, which experiences a complex process of cycles {sup {yields}} quasi-periodic oscillation {sup {yields}} periodic doubling cascade {sup {yields}} chaos.
The existence, uniqueness and regularity of time-periodic solutions to the Navier–Stokes equations in the three-dimensional whole space are investigated. We consider the Navier–Stokes equations with a non-zero drift term corresponding to the physical model of a fluid flow around a body that moves with a non-zero constant velocity. The existence of a strong time-periodic solution is shown for small time-periodic data. It is further shown that this solution is unique in a large class of weak solutions that can be considered physically reasonable. Finally, we establish regularity properties for any strong solution regardless of its size. (paper)
Rogers, J.; Porter, K.
2012-03-01
This paper updates previous work that describes time period-based and other approximation methods for estimating the capacity value of wind power and extends it to include solar power. The paper summarizes various methods presented in utility integrated resource plans, regional transmission organization methodologies, regional stakeholder initiatives, regulatory proceedings, and academic and industry studies. Time period-based approximation methods typically measure the contribution of a wind or solar plant at the time of system peak - sometimes over a period of months or the average of multiple years.
Polanco Martínez, Josue M.; Medina-Elizalde, Martin; Burns, Stephen J.; Jiang, Xiuyang; Shen, Chuan-Chou
2015-04-01
It has been widely accepted by the paleoclimate and archaeology communities that extreme climate events (especially droughts) and past climate change played an important role in the cultural changes that occurred in at least some parts of the Maya Lowlands, from the Pre-Classic (2000 BC to 250 AD) to Post-Classic periods (1000 to 1521 AD) [1, 2]. In particular, a large number of studies suggest that the decline of the Maya civilization in the Terminal Classic Period was greatly influenced by prolonged severe drought events that probably triggered significant societal disruptions [1, 3, 4, 5]. Going further on these issues, the aim of this work is to detect climate regime shifts in several paleoclimate time series from the Yucatán Peninsula (México) that have been used as rainfall proxies [3, 5, 6, 7]. In order to extract information from the paleoclimate data studied, we have used a change point method [8] as implemented in the R package strucchange, as well as the RAMFIT method [9]. The preliminary results show for all the records analysed a prominent regime shift between 400 to 200 BCE (from a noticeable increase to a remarkable fall in precipitation), which is strongest in the recently obtained stalagmite (Itzamna) delta18-O precipitation record [7]. References [1] Gunn, J. D., Matheny, R. T., Folan, W. J., 2002. Climate-change studies in the Maya area. Ancient Mesoamerica, 13(01), 79-84. [2] Yaeger, J., Hodell, D. A., 2008. The collapse of Maya civilization: assessing the interaction of culture, climate, and environment. El Niño, Catastrophism, and Culture Change in Ancient America, 197-251. [3] Hodell, D. A., Curtis, J. H., Brenner, M., 1995. Possible role of climate in the collapse of Classic Maya civilization. Nature, 375(6530), 391-394. [4] Aimers, J., Hodell, D., 2011. Societal collapse: Drought and the Maya. Nature 479(7371), 44-45 (2011). [5] Medina-Elizalde, M., Rohling, E. J., 2012. Collapse of Classic Maya civilization related to modest reduction
The presence of motion artifacts in photoplethysmographic (PPG) signals is one of the major obstacles in the extraction of reliable cardiovascular parameters in continuous monitoring applications. In the current paper we present an algorithm for motion artifact detection based on the analysis of the variations in the time and the period domain characteristics of the PPG signal. The extracted features are ranked using a normalized mutual information feature selection algorithm and the best features are used in a support vector machine classification model to distinguish between clean and corrupted sections of the PPG signal. The proposed method has been tested in healthy and cardiovascular diseased volunteers, considering 11 different motion artifact sources. The results achieved by the current algorithm (sensitivity—SE: 84.3%, specificity—SP: 91.5% and accuracy—ACC: 88.5%) show that the current methodology is able to identify both corrupted and clean PPG sections with high accuracy in both healthy (ACC: 87.5%) and cardiovascular diseases (ACC: 89.5%) context. (paper)
Many particle accelerators and colliders throughout the world make use of superconducting magnets to focus highly relativistic beams. These magnets are cooled to ∼4.2 degree K For practical reasons, the beam pipes, encircled by the magnets, also operate at these cryogenic temperatures. This paper presents a theoretical model for determining pressure profiles, in space and time, stemming from either hydrogen or helium gas leak into the cold-bore tube with appendage pumps located at periodic intervals. It is shown that a wave-like pressure gradient propagates from the leak source at a rate which is dependent on the leak magnitude, gas species, speed and location of appendage pumps, and the geometry and effective roughness of the cold-bore tube. Steady-state, linear pressure gradients eventually equilibrate between the appendage pumps in a magnitude commensurate with both the adsorption isotherm of the species and mass flow in the beam pipe. Results are given for a variety of conditions relevant to the Relativistic Heavy Ion Collider being constructed at Brookhaven, and a general procedure, with expressions, is provided for the making of similar calculations in other installations
In the past two years the reactor was operated 1653 hours at steady - state full power (250 kW). During the same period, July 1978 - June 1980, 680 applications for reactor use were submitted. Total reactor time utilized (6843 hours) is increased in comparison with the previous two years period. Some modernization to the equipment is also made
2010-04-01
... 25 Indians 1 2010-04-01 2010-04-01 false What is the time period in which the Director must investigate a tribe's compliance with a TERA? 224.116 Section 224.116 Indians BUREAU OF INDIAN AFFAIRS... period in which the Director must investigate a tribe's compliance with a TERA? (a) If the...
Rogan, Paul J.
This research attempted to identify differences, or lack of them, in time orientation of Caucasian, Black and Chicano young male first offenders at various periods of imprisonment; beginning, middle, and end. The instrument that was chosen to measure time orientation was a combination of two questionnaires--the Time Competence scale of the…
Xiaoyuan CHU; Yujie WANG; Yiping XIA; Yun WU; Lin CHEN
2009-01-01
In order to provide a basis for water conservation in the restoration of vegetation for an urban water resource area, we studied the generation of runoff characteristics in four typical forests over three time periods in Jinyun Mountain, Chongqing City, based on the observation data of rainfall and runoff processes during the period 2002-2005. The results show that: 1) Rainfall was distributed evenly during the years 2002-2005. Annual rainfall variability was 4.46% and coefficient of variation was 0.0618. Average monthly rainfall tended towards a normal distribution N (113.8, 45972). 2) Both precipitation and runoff can be clearly divided into a dry and a wet season. The dry season was from October to March and the wet season from April to September. Most of annual runoff of the four forest stands occurred in the wet season. The surface runoff in the wet season accounted for more than 85% of the annual runoff, and more than 75% of underground runoff. 3) Both peak values of surface runoff and underground runoff occurred in June. The relation between monthly rainfall and surface/underground runoff was fitted by the model W = aP2 + bP + c. The order of annual surface runoff was as follows: Phyllostachys pub-escens forest > shrub forest > mixed Pinus massoniana-broadleaf forest > evergreen broad-leaved forest. The annual underground runoff was evergreen broad-leaved forest > mixed Pinus massoniana-broadleaf forest >Phyl-lostachys pubescens forest > shrub forest. 4) Under similar rainstorms events, the order of the surface runoff coefficient was: evergreen broad-leaved forest mixed Pinus massoniana-broadleaf forest > Phyllostachys pubescens forest > shrub forest. The relation between rainstorms and surface runoff was fitted by the linear relationship: Q = mp-n. Both mixed Pinus massoniana-broadleaf forest and evergreen broad-leaved forest have better flood regulation effects on an annual and monthly basis and per individual rainstorm. The function of Phyllostachys
Theresa Hunter; Georg’ann Cattelona
2014-01-01
Background: The early post-partum period is a crucial time for breastfeeding support. Mothers who have physical and emotional support during this period are more likely to be successful in breastfeeding. This study examined the relationship between father involvement and support for breast feeding initiation and duration in first-time mothers. Methods: Overall, 146 women who attended a childbirth education class or breastfeeding course at BABS were asked to fill out the Chil...
Pereira, Ana C; Reis, Marco S; Saraiva, Pedro M; Marques, José C
2010-02-15
Wine is one of the world's higher value agricultural products. The present work is centred on Madeira wine, a fine and prestigious example among Portuguese liqueur wines,with the main goal to deepen our understanding of relevant phenomena going on during the winemaking process, in particular during ageing of "Malmsey" Madeira wine. In this paper we present the results obtained from the chemical characterization of how its aroma composition evolves during ageing, and the development of a robust framework for analyzing the identity of aged Madeira wines. An extended ageing period was considered, covering a time frame of twenty years, from which several samples were analyzed in terms of their aromatic composition. The multivariate structure of this chemical information was then processed through multivariate statistical feature extraction techniques such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), in order to identify the relevant patterns corresponding to trends associated with wine ageing. Classification methodologies for age prediction were developed, using data from the lower dimensional sub-spaces obtained after projecting the original data to the latent variable spaces provided by PCA or PLS-DA. Finally, the performance for each classification methodology developed was evaluated according to their error rates using cross-validation methodologies (Leave-One-Out and k-fold Monte Carlo). Results obtained so far show that quite interesting classification performances can indeed be achieved, despite the natural variability present in wine products. These results also provide solid bases which can be used to build up available frameworks which assist quality monitoring and identity assurance tasks. PMID:20103138
Haff, G Gregory; Jackson, Janna R; Kawamori, Naoki; Carlock, Jon M; Hartman, Michael J; Kilgore, J Lon; Morris, Robert T; Ramsey, Michael W; Sands, William A; Stone, Michael H
2008-03-01
The purpose of this investigation was to study the effects of an 11-week training period performed by female weightlifters. Two weeks before this investigation, baseline measures for total testosterone, cortisol, and testosterone:cortisol ratio were collected. The 11-week training program consisted of the core exercises (i.e., clean, clean and jerk, and snatch) and other supplemental exercises (i.e., clean pull, snatch pull, squat, and front squat). Hormonal, isometric, and dynamic middle thigh pull force-time curve characteristics were assessed biweekly throughout the duration of the investigation, whereas volume load and training intensity were assessed weekly throughout the investigation. The testosterone:cortisol ratio of the baseline (1.19 +/- 0.64) was significantly different from the ratio of weeks 1 (0.67 +/- 0.36) and 9 (0.94 +/- 0.66). When the week-to-week values were compared, week 1 (0.67 +/- 0.36) was significantly different (P < 0.05; eta = 0.84) from week 3 (1.06 +/- 0.54). A very strong correlation (r = -0.83; r = 0.69) was found between the percentage change of the testosterone:cortisol ratio and volume load from weeks 1 to 11. Moderate to very strong correlations were noted between the percentage change in volume load and isometric peak force, peak force during the 30% isometric peak force trial, and peak force during the 100-kg trial during the 11 weeks of training. The primary finding of this study was that alterations in training volume load can result in concomitant changes in the anabolic-to-catabolic balance, as indicated by the testosterone:cortisol ratio, and the ability to generate maximal forces. PMID:18550958
Gorceag Lilia T
2011-04-01
Full Text Available Abstract Background Trafficking in women is a widespread human rights violation commonly associated with poor mental health. Yet, to date, no studies have used psychiatric diagnostic assessment to identify common forms of mental distress among survivors returning to their home country. Methods A longitudinal study was conducted of women aged 18 and over who returned to Moldova between December 2007 and December 2008 registered by the International Organisation for Migration as a survivor of human trafficking. Psychiatric diagnoses in women at a mean of 6 months after return (range 2-12 months were made by a trained Moldavian psychiatrist using the Structured Clinical Interview for DSM-IV, and compared with diagnoses recorded in the same women within 5 days of return. We described the socio-demographic characteristics of the women in the sample including both pre and post-trafficking information. We then described the distribution of mental health diagnoses recorded during the crisis intervention phase (1-5 days after return and the re-integration phase (2-12 months after return. We compared diagnoses at the patient level between the two time points by tabulating the diagnoses and carrying out a kappa test of agreement and the Stuart-Maxwell test for marginal homogeneity (an extension of the McNemar test to kxk table. Results 120/176 (68% eligible women participated. At 2-12 months after their return, 54% met criteria for at least one psychiatric diagnoses comprising post-traumatic stress disorder (PTSD alone (16%; co-morbid PTSD (20%; other anxiety or mood disorder (18%. 85% of women who had been diagnosed in the crisis phase with co-morbid PTSD or with another anxiety or mood disorder sustained a diagnosis of any psychiatric disorder when followed up during rehabilitation. Conclusions Trafficked women returning to their country of origin are likely to suffer serious psychological distress that may endure well beyond the time they return. Women
Zhang Long [College of Mathematics and System Sciences, Xinjiang University, Urumqi 830046 (China)], E-mail: longzhang_xj@sohu.com; Teng Zhidong [College of Mathematics and System Sciences, Xinjiang University, Urumqi 830046 (China)], E-mail: zhidong@xju.edu.cn
2008-12-15
In this paper, we study two species predator-prey Lotka-Volterra type dispersal system with periodic coefficients in two patches, in which both the prey and predator species can disperse between two patches. By utilizing analytic method, sufficient and realistic conditions on permanence and the existence of periodic solution are established. The theoretical results are confirmed by a special example and numerical simulations.
Oxenløwe, Leif Katsuo; Galili, Michael; Mulvad, Hans Christian Hansen;
2007-01-01
A 0.8 ps flat top pulse is generated using a long-period fibre grating and used as control pulse for the first time in a 320 Gb/s demultiplexer. The effect is an increased error-free timing tolerance...
We present the results of a systematic search in ∼14 years of Rossi X-ray Timing Explorer All-Sky Monitor (ASM) data for evidence of periodicities. Two variations of the commonly used Fourier analysis search method have been employed to significantly improve upon the sensitivity achieved by Wen et al. in 2006, who also searched for periodicities in ASM data. In addition, the present search is comprehensive in terms of sources studied and frequency range covered, and has yielded the detection of the signatures of the orbital periods of eight low-mass X-ray binary systems and of ten high-mass X-ray binaries not listed in the tables of Wen et al. Orbital periods, epochs, signal amplitudes, modulation fractions, and folded light curves are given for each of these systems. Seven of the orbital periods are the most precise reported to date. In the course of this work, the 18.545 day orbital period of IGR J18483-0311 was co-discovered, and the first detections in X-rays were made of the ∼3.9 day orbital period of LMC X-1 and the ∼3.79 hr orbital period of 4U 1636-536. The results inform future searches for orbital and other periodicities in X-ray binaries.
Van Greuningen Malou
2012-12-01
Full Text Available Abstract Background The high cost of training and the relatively long period of training for physicians make it beneficial to stimulate physicians to retire later. Therefore, a better understanding of the link between the factors influencing the decision to retire and actual turnover would benefit policies designed to encourage later retirement. This study focuses on actual GP turnover and the determining factors for this in the Netherlands. The period 2003–2007 saw fewer GPs retiring from general practice than the period 1998–2002. In addition, GPs’ retirement age was higher in 2003–2007. For these two periods, we analysed work perception, objective workload and reasons for leaving, and related these with the probability that GPs would leave general practice at an early age. Methods In 2003, a first retrospective survey was sent to 520 self-employed GPs who had retired between 1998 and 2002. In 2008, the same survey was sent to 405 GPs who had retired between 2003 and 2007. The response rates were 60% and 54%, respectively. Analyses were done to compare work perception, objective workload, external factors and personal reasons for retiring. Results For both male and female GPs, work perception was different in the periods under scrutiny: both groups reported greater job satisfaction and a lower degree of emotional exhaustion in the later period, although there was no notable difference in subjective workload. The objective workload was lower in the second period. Moreover, most external factors and personal reasons that may contribute to the decision to retire were reported as less important in the second period. There was a stronger decrease in the probability that female GPs leave general practice within one year than for male GPs. This underscores the gender differences and the need for disaggregated data collection. Conclusions The results of this study suggest that the decrease in the probability of GPs leaving general practice
Tanrıver, Mehmet
2015-04-01
In this article, a period analysis of the late-type eclipsing binary VV UMa is presented. This work is based on the periodic variation of eclipse timings of the VV UMa binary. We determined the orbital properties and mass of a third orbiting body in the system by analyzing the light-travel time effect. The O-C diagram constructed for all available minima times of VV UMa exhibits a cyclic character superimposed on a linear variation. This variation includes three maxima and two minima within approximately 28,240 orbital periods of the system, which can be explained as the light-travel time effect (LITE) because of an unseen third body in a triple system that causes variations of the eclipse arrival times. New parameter values of the light-time travel effect because of the third body were computed with a period of 23.22 ± 0.17 years in the system. The cyclic-variation analysis produces a value of 0.0139 day as the semi-amplitude of the light-travel time effect and 0.35 as the orbital eccentricity of the third body. The mass of the third body that orbits the eclipsing binary stars is 0.787 ± 0.02 M⊙, and the semi-major axis of its orbit is 10.75 AU.
2010-07-01
... 41 Public Contracts and Property Management 4 2010-07-01 2010-07-01 false Does the 2-year time period in Â§ 302-2.8 include time that I cannot travel and/or transport my household effects due to... time that I cannot travel and/or transport my household effects due to shipping restrictions to or...
Yongzhi Liao
2013-01-01
Full Text Available This paper is concerned with the problem of the existence, uniqueness, and global exponential stability of almost periodic solution for neutral-type Cohen-Grossberg neural networks with time delays. Based on fixed point theory and Lyapunov functional, several sufficient conditions are established for the existence, uniqueness, and global exponential stability of almost periodic solution for the above system. Finally, an example and numerical simulations are given to illustrate the feasibility and effectiveness of our main results.
Yongzhi Liao; Wenquan Wu; Tianwei Zhang
2013-01-01
This paper is concerned with the problem of the existence, uniqueness, and global exponential stability of almost periodic solution for neutral-type Cohen-Grossberg neural networks with time delays. Based on fixed point theory and Lyapunov functional, several sufficient conditions are established for the existence, uniqueness, and global exponential stability of almost periodic solution for the above system. Finally, an example and numerical simulations are given to illustrate the feasibility...
Jha, Basant K.; Ajibade, Abiodun O.
2012-04-01
This article investigates the natural convection flow of viscous incompressible fluid in a channel formed by two infinite vertical parallel plates. Fully developed laminar flow is considered in a vertical channel with steady-periodic temperature regime on the boundaries. The effect of internal heating by viscous dissipation is taken into consideration. Separating the velocity and temperature fields into steady and periodic parts, the resulting second order ordinary differential equations are solved to obtain the expressions for velocity, and temperature. The amplitudes and phases of temperature and velocity are also obtained as well as the rate of heat transfer and the skin-friction on the plates. In presence of viscous dissipation, fluids of relatively small Prandtl number has higher temperature than the channel plates and as such, heat is being transferred from the fluid to the plate.
Garde, Ainara; Giraldo Giraldo, Beatriz; Jané Campos, Raimon; Latshang, T D; Turk, A.J.; Hess, T.; Bosch, M M; Barthelmes, D.; Merz, T M; Pichler Hefti, J.; Schoch, O.D.; Bloch, Konrad E
2015-01-01
This work investigates the performance of cardiorespiratory analysis detecting periodic breathing (PB) in chest wall recordings in mountaineers climbing to extreme altitude. The breathing patterns of 34 mountaineers were monitored unobtrusively by inductance plethysmography, ECG and pulse oximetry using a portable recorder during climbs at altitudes between 4497 and 7546 m on Mt. Muztagh Ata. The minute ventilation (VE) and heart rate (HR) signals were studied, to identify visually scored ...
Wu, Yu-Tzu; Lee, Hsin-yi; Norton, Samuel; Prina, A Matthew; Fleming, Jane; Matthews, Fiona E.; Brayne, Carol
2014-01-01
This is the accepted version of the following article: Wu, Y.-T., Lee, H.-y., Norton, S., Prina, A. M., Fleming, J., Matthews, F. E. and Brayne, C. (2014), Period, birth cohort and prevalence of dementia in mainland China, Hong Kong and Taiwan: a meta-analysis. Int. J. Geriat. Psychiatry. doi: 10.1002/gps.4148, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/gps.4148/abstract
Ku, Po-Wen; Stevinson, Clare; Chen, Li-Jung
2012-01-01
Background Few studies have explored the relations between naturally occurring changes in physical activity and cognitive performance in later life. This study examined prospective associations between changes in physical activity and cognitive performance in a population-based sample of Taiwanese older adults during an 11-year period. Methods Analyses were based on nationally representative data from the Taiwan Health and Living Status of the Elderly Survey collected in 1996, 1999, 2003, and...
Xiao Yu Wang
Full Text Available Different locations and study periods were used in the assessment of the relationships between heatwaves and mortality. However, little is known about the comparability and consistency of the previous effect estimates in the literature. This study assessed the heatwave-mortality relationship using different study periods in the three largest Australian cities (Brisbane, Melbourne and Sydney.Daily data on climatic variables and mortality for the three cities were obtained from relevant government agencies between 1988 and 2011. A consistent definition of heatwaves was used for these cities. Poisson generalised additive model was fitted to assess the impact of heatwaves on mortality.Non-accidental and circulatory mortality significantly increased during heatwaves across the three cities even with different heatwave definitions and study periods. Using the summer data resulted in the largest increase in effect estimates compared to those using the warm season or the whole year data.The findings may have implications for developing standard approaches to evaluating the heatwave-mortality relationship and advancing heat health warning systems. It also provides an impetus to methodological advance for assessing climate change-related health consequences.
Shit, Anindita; Chattopadhyay, Sudip; Chaudhuri, Jyotipratim Ray
2011-06-01
We explore the Brownian dynamics in the quantum regime (by investigating the quantum Langevin and Smoluchowski equations) in terms of an effective time-independent Hamiltonian in the presence of a rapidly oscillating field. We achieve this by systematically expanding the time-dependent system-reservoir Hamiltonian in the inverse of driving frequency with a systematic time-scale separation and invoking a quantum gauge transformation within the framework of Floquet theorem. PMID:21797289
Erwin; Gunanti; Ekowati Handharyani; Deni Noviana
2016-01-01
Aim: The success of a skin graft in a cat is highly dependent on the granulation formed by the base of recipient bed. Granulation by the base of recipient bed will form after several days after injury. This research aimed to observe subjective and objective profile of skin graft recovery on forelimb of cats with different periods of donor skin placement. Materials and Methods: Nine male Indonesian local cats aged 1-2 years old, weighing 3-4 kg were divided into three groups. The first surg...
Our aim is to prove existence and uniqueness of time-periodic strong solutions with finite kinetic energy for the Navier–Stokes equations in R3. For this, appropriate conditions are imposed on the external force, together with a smallness condition involving the viscosity of the fluid and the period of motion. We extend the method we have recently used to construct steady states with finite kinetic energy to the time-periodic case. First, existence and uniqueness of strong solutions with finite kinetic energy are established for a linearized version of the problem, using the Galerkin method and the Fourier transform in the space variables. Then, a strong solution with finite kinetic energy for the nonlinear problem is obtained by means of the contraction mapping principle. We also show that such a solution satisfies the energy equality and is unique within a class of weak solutions
We have studied the stability of the elemental spectrum in the hair of the patients with rhino-pharyngeal cancer. The method of polynomial regressions has been used. The trace elements matrix has been determined at different interval of time. The moment before starting the radiotherapy treatment, has been considered as the moment zero. The study of time evolution of the elemental spectrum indicated a tendency of stability. (authors)
Stefania Garzoli; Adele Pirolli; Elisabetta Vavala; Antonella Di Sotto; Gianni Sartorelli; Mijat Božović; Letizia Angiolella; Gabriela Mazzanti; Federico Pepi; Rino Ragno
2015-01-01
A comprehensive study on essential oils (EOs) extracted from some Mentha suaveolens L. samples, collected in the countryside of Tarquinia, is reported. In this study, the procedure for essential oil preparation, in terms of harvesting and extraction time, was analyzed in detail for the first time. The GC/MS analysis, carried out on 18 samples, revealed that piperitenone oxide (PO), the main essential oils’ chemical constituent, is primarily responsible for the related antifungal activity. Ne...
Solar EUV Variability from FISM and SDO/EVE During Solar Minimum, Active, and Flaring Time Periods
Chamberlin, Phillip C.
2011-01-01
The Living With a Star (LWS) Focus Science Team has identified three periods of different solar activity levels for which they will be determining the Earth's Ionosphere and Thermosphere response. Not only will the team be comparing individual models (e.g. FLIP, T1MEGCM, GLOW) outcome driven by the various levels of solar activity, but the models themselves will also be compared. These models all rely on the input solar EUV (0.1 -190 nm) irradiance to drive the variability. The Flare Irradiance Spectral Model (FISM) and the EUV Variability Experiment (EVE) onboard provide the Solar Dynamics Observatory (SDO) provide the most accurate quantification of these irradiances. Presented and discussed are how much the solar EUV irradiance changes during these three scenarios, both as a function of activity and wavelength.
Garzoli, Stefania; Pirolli, Adele; Vavala, Elisabetta; Di Sotto, Antonella; Sartorelli, Gianni; Božović, Mijat; Angiolella, Letizia; Mazzanti, Gabriela; Pepi, Federico; Ragno, Rino
2015-01-01
A comprehensive study on essential oils (EOs) extracted from some Mentha suaveolens L. samples, collected in the countryside of Tarquinia, is reported. In this study, the procedure for essential oil preparation, in terms of harvesting and extraction time, was analyzed in detail for the first time. The GC/MS analysis, carried out on 18 samples, revealed that piperitenone oxide (PO), the main essential oils' chemical constituent, is primarily responsible for the related antifungal activity. Nevertheless, EOs with lower PO content indicate that other chemicals, such as para-cymenene, may participate in exerting the EOs' antifungal effect. Furthermore, the bacterial reverse mutation assay highlighted lack of mutagenic effect in all tested samples. Analysis of the results indicated that for higher activity, the essential oils should be produced with 3 h maximum hydrodistillation, regardless of the harvesting time. Differently, the maximum essential oil yield can be obtained in August and the highest piperitenone oxide percentage is obtainable in July. PMID:26016551
Stefania Garzoli
2015-05-01
Full Text Available A comprehensive study on essential oils (EOs extracted from some Mentha suaveolens L. samples, collected in the countryside of Tarquinia, is reported. In this study, the procedure for essential oil preparation, in terms of harvesting and extraction time, was analyzed in detail for the first time. The GC/MS analysis, carried out on 18 samples, revealed that piperitenone oxide (PO, the main essential oils’ chemical constituent, is primarily responsible for the related antifungal activity. Nevertheless, EOs with lower PO content indicate that other chemicals, such as para-cymenene, may participate in exerting the EOs’ antifungal effect. Furthermore, the bacterial reverse mutation assay highlighted lack of mutagenic effect in all tested samples. Analysis of the results indicated that for higher activity, the essential oils should be produced with 3 h maximum hydrodistillation, regardless of the harvesting time. Differently, the maximum essential oil yield can be obtained in August and the highest piperitenone oxide percentage is obtainable in July.
Daryush Talei
2013-01-01
Full Text Available Germination is a key process in plants' phenological cycles. Accelerating this process could lead to improvment of the seedling growth as well as the cultivation efficiency. To achieve this, the effect of microwave frequency on the germination of rice seeds was examined. The physiological feedbacks of the MR 219 rice variety in terms of seed germination rate (GR, germination percentage (GP, and mean germination time (MGT were analyzed by exposing its seeds to 2450 MHz of microwave frequency for one, four, seven, and ten hours. It was revealed that exposing the seeds to the microwave frequency for 10 hours resulted in the highest GP. This treatment led to 100% of germination after three days with a mean germination time of 2.1 days. Although the other exposure times of microwave frequency caused the moderate effects on germination with a GPa3 ranged from 93% to 98%, they failed to reduce the MGTa3. The results showed that ten-hour exposure times of microwave frequency for six days significantly facilitated and improved the germination indices (primary shoot and root length. Therefore, the technique is expected to benefit the improvement of rice seed germination considering its simplicity and efficacy in increasing the germination percentage and rate as well as the primary shoot and root length without causing any environmental toxicity.
Shit, Anindita [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Chattopadhyay, Sudip, E-mail: sudip_chattopadhyay@rediffmail.com [Department of Chemistry, Bengal Engineering and Science University, Shibpur, Howrah 711103 (India); Ray Chaudhuri, Jyotipratim, E-mail: jprc_8@yahoo.com [Department of Physics, Katwa College, Katwa, Burdwan 713130 (India)
2014-03-18
Highlights: • Nonadiabatic dynamics of quantum particle under the impact of high-frequency force. • Formulation of time-independent dynamics via Floquet and Kapitza schemes. • Manipulation of external force parameters allows us to control the escape rate. • Increase of (amplitudes/frequency) causes the system to decay faster, in general. • Crossover temperature increases in the presence of the field. - Abstract: Escape under the action of the external modulation constitutes a nontrivial generalization of an conventional Kramers rate because the system is away from thermal equilibrium. A derivation of this result from the point of view of Langevin dynamics in the frame of Floquet theorem in conjunction with the Kapitza–Landau time window (that leads to an attractive description of the time-dependent quantum dynamics in terms of time-independent one) has been provided. The quantum escape rate in the intermediate-to-high and very-high damping regime so obtained analytically using the phase space formalism associated with the Wigner distribution and path-integral formalism bears a quantum correction that depends strongly on the barrier height. It is shown that an increase of (amplitude/frequency) ratio causes the system to decay faster, in general. The crossover temperature between tunneling and thermal activation increases in the presence of field so that quantum effects in the escape are relevant at higher temperatures.
Highlights: • Nonadiabatic dynamics of quantum particle under the impact of high-frequency force. • Formulation of time-independent dynamics via Floquet and Kapitza schemes. • Manipulation of external force parameters allows us to control the escape rate. • Increase of (amplitudes/frequency) causes the system to decay faster, in general. • Crossover temperature increases in the presence of the field. - Abstract: Escape under the action of the external modulation constitutes a nontrivial generalization of an conventional Kramers rate because the system is away from thermal equilibrium. A derivation of this result from the point of view of Langevin dynamics in the frame of Floquet theorem in conjunction with the Kapitza–Landau time window (that leads to an attractive description of the time-dependent quantum dynamics in terms of time-independent one) has been provided. The quantum escape rate in the intermediate-to-high and very-high damping regime so obtained analytically using the phase space formalism associated with the Wigner distribution and path-integral formalism bears a quantum correction that depends strongly on the barrier height. It is shown that an increase of (amplitude/frequency) ratio causes the system to decay faster, in general. The crossover temperature between tunneling and thermal activation increases in the presence of field so that quantum effects in the escape are relevant at higher temperatures
Wetstein, Matthew; Hays, Brianna; Nguyen, Alyssa
2011-01-01
This study seeks to extend the literature on higher education enrollment patterns during times of recession by examining patterns of enrollment and successful course completion in one of the world's largest higher education systems--the California Community College system. The data are drawn from publicly available data sources on the web. CCC…
Dryden, Joe
2013-01-01
This case represents a multitude of leadership dilemmas created by financial exigencies and the difficult decisions that must be made during times of economic austerity. Under the best of circumstances, deciding between programmatic elimination and/or employee termination is agonizing, onerous, and filled with political and social ramifications.…
Sicard, Pierre; Serra, Romain; Rossello, Philippe
2016-08-01
The hourly ozone (O3) data from 332 background monitoring stations, spread in France, were analyzed over the period 1999-2012 and short-term trends were calculated. In the current climate change context, the calculation of human health- and vegetation-relevant metrics, and of associated trends, provides a consistent method to establish proper and effective policies to reduce the adverse O3 effects. The generation of optimal O3 maps, for risk and exposure assessment, is challenging. To overcome this issue, starting from a set of stations, a hybrid regression-interpolation approach was proposed. Annual surface O3 metrics, O3 human health metrics (number of exceedances of daily maximum 8-h values greater than 60 ppb and SOMO35) and O3 vegetation impact metrics (AOT40 for vegetation and forests) were investigated at individual sites. Citizens are more exposed to high O3 levels in rural areas than people living in the cities. The annual mean concentrations decreased by -0.12ppbyear(-1) at rural stations, and the significant reduction at 67% of stations, particularly during the warm season, in the number of episodic high O3 concentrations (e.g. 98th percentile, -0.19ppbyear(-1)) can be associated with the substantial reductions in NOx and VOCs emissions in the EU-28 countries since the early 1990s Inversely, the O3 background level is rising at 76% of urban sites (+0.14ppbyear(-1)), particularly during the cold period. This rise can be attributed to increases in imported O3 by long-range transport and to a low O3 titration by NO due to the reduction in local NOx emissions. The decrease in health-related and vegetation-relevant O3 metrics, at almost all stations, is driven by decreases in regional photochemical O3 formation and in peak O3 concentrations. The short-term trends highlight that the threat to population and vegetation declined between 1999 and 2012 in France, demonstrating the success of European control strategies over the last 20 years. However, for all
Thermoconvective instabilities in horizontal fluid layers are discussed with emphasis on the Rayleigh-Benard model problem. Steady solutions and time-dependent phenomena (relaxation oscillations and transition to turbulence) are studied within the nonlinear Boussinesq-Oberbeck approximation. Homogeneous steady solutions, limit cycles, and inhomogeneous (ordered) spatial structures are also studied in simple reaction-diffusion systems. Lastly, the non-periodic attractor that appears at large Rayleigh numbers in the truncated Boussinesq-Oberbeck model of Lorenz, is constructed, and a discussion of turbulent behavior is given. (author)
Thermo convective instabilities in horizontal fluid layers are discussed with emphasis on the Rayleigh-Bernard model problem. Steady solutions and time-dependent phenomena (relaxation oscillations and transition to turbulence) are studied within the nonlinear Boussinesq-Oberbeck approximation. Homogeneous steady solutions, limit cycles, and inhomogeneous (ordered) spatial structures are also studied in simple reaction-diffusion systems. Lastly, the non-periodic attractor that appears at large Rayleigh numbers in the truncated Boussinesq-Oberbeck model of Lorenz, is constructed, and a discussion of turbulent behavior is given. (Author) 105 refs
Chen, Hai Yang
2014-05-01
We have analyzed the effect of various system parameters and external time-dependent field on the transport properties of monolayer graphene-based double-barrier(well) structures under a time-periodic potential. Results indicate that the Klein tunneling still exists. Besides, the transmission probability, conductivity, shot noise, and Fano factor exhibit various types of oscillatory behavior with changes in the system parameters, and they are either improved or suppressed in the presence of the time-periodic potential. We have also discussed the reasons underlying these phenomena. The results obtained in this study demonstrate that the transport properties can be controlled by manipulating the structural parameters of the system and the external field strength.
Leandri Kruger
2016-01-01
Full Text Available Hazard-prone areas in southern Africa experience many natural hazards, which include cyclones, floods and droughts. The severe climatic conditions of southern Africa have an especially large impact on the agricultural practices of small-scale farmers. These hazards should be mitigated to ensure more resilient communities and food security. This study mainly focuses on the timing of agricultural production in hazard-prone areas to prevent losses at peak-risk periods by adapting the agricultural cycle. This study focuses on the agricultural activities of small-scale farmers in Malawi, Madagascar and Mozambique. A literature review is presented, and a mixed-method research design were followed to determine the timing of production followed by these small-scale farmers and its impact on production and food security. Although this study found that the small-scale farmers generally plant with the first rains, it is recommended by literature that early planting should be practised to ensure optimal production. It is also recommended that small-scale farmers should implement watermanagement techniques for dry periods, and when farmers practice late planting, the use of residual-moisture retention should be utilised as a mitigation measure. This will in effect ensure that the communities are less vulnerable during peak-risk periods by improving or ensuring food security. Therefore, adapting the planting and production time in these hazardprone areas at peak-risk periods could limit losses and increase communities’ resilience.
Theresa Hunter
2014-12-01
Full Text Available Background: The early post-partum period is a crucial time for breastfeeding support. Mothers who have physical and emotional support during this period are more likely to be successful in breastfeeding. This study examined the relationship between father involvement and support for breast feeding initiation and duration in first-time mothers. Methods: Overall, 146 women who attended a childbirth education class or breastfeeding course at BABS were asked to fill out the Childbirth Experiences Survey, which explored key topics such as (1 breastfeeding initiation, (2 early post-partum breastfeeding, (3 breastfeeding plan, (4 post-partum breastfeeding support and (5 breast feeding duration. This was a voluntary self-reported questionnaire. The surveys were completed by the mothers during the post-partum period. Results: 45.9% (n=67 of mothers received helped from their husband or partner with breastfeeding while in the hospital, while 54.1% (n=79 of mothers did not receive support from their partners. Mothers who received early post-partum breastfeeding support were more likely to continue breastfeeding after leaving the hospital. Conclusion: First-time mothers who identified as having breastfeeding support from their partners, the infant’s father, during the early post-partum period were more likely to initiate breastfeeding and had longer breastfeeding durations.
Auchincloss, Amy H; Moore, Kari A B; Moore, Latetia V; Diez Roux, Ana V
2012-11-01
Access to healthy foods has received increasing attention due to growing prevalence of obesity and diet-related health conditions yet there are major obstacles in characterizing the local food environment. This study developed a method to retrospectively characterize supermarkets for a single historic year, 2005, in 19 counties in 6 states in the USA using a supermarket chain-name list and two business databases. Data preparation, merging, overlaps, added-value amongst various approaches and differences by census tract area-level socio-demographic characteristics are described. Agreement between two food store databases was modest: 63%. Only 55% of the final list of supermarkets were identified by a single business database and selection criteria that included industry classification codes and sales revenue ≥$2 million. The added-value of using a supermarket chain-name list and second business database was identification of an additional 14% and 30% of supermarkets, respectively. These methods are particularly useful to retrospectively characterize access to supermarkets during a historic period and when field observations are not feasible and business databases are used. PMID:22883050
Timing Spectroscopy of Quasi-Periodic Oscillations in the Low-Mass X-ray Neutron Star Binaries
Titarchuk, L G; Kuznetsov, S; Titarchuk, Lev; Osherovich, Vladimir; Kuznetsov, Sergey
1999-01-01
Precise simultaneous measurements of the frequencies of the two kiloHertz quasi-periodic oscillations (referred in the literature as upper and lower kHz QPOs) cast doubts on the validity of the simple beat-frequency interpretation and some of the modifications introduced to explain the results of the varying frequency difference. A new model explains the variation of the frequency difference suggesting that the upper kHz QPO,namely nu_h is an upper hybrid frequency of the Keplerian oscillator under the influence of the Coriolis force and the lower kHz QPO is the Keplerian frequency nu_K. Such an oscillator has two branches characterized by high frequency nu_h (around 1 kHz) and by low frequency nu_L (around 50 Hz). The frequency nu_L depends strongly on the angle, delta between the normal to the neutron star disk and Omega - the angular velocity of the magnetosphere surrounding the neutron star. In the lower part of the QPO spectrum (around 10 Hz), this model identifies the frequency of radial viscous oscilla...
Shafiee, Afshin
2011-01-01
We consider the evolution of a two-state quantum system (a spin 1/2 particle) in both the framework of standard quantum mechanics and under the decoherence regime. The former approach on this issue is the well-known quantum flipping process of a dichotomic system subjected to a time-dependent magnetic field. In the latter approach, utilizing the Spin-Boson model to describe the interaction of system with its environment, we derive the Born-Markov master equation to obtain the decoherence time. It is possible to show that under some legitimate conditions, one may find a potential conflict between the predictions of decoherence theory and the result observed in a typical quantum flipping experiment.
Daryush Talei; Alireza Valdiani; Mahmood Maziah; Mohammad Mohsenkhah
2013-01-01
Germination is a key process in plants' phenological cycles. Accelerating this process could lead to improvment of the seedling growth as well as the cultivation efficiency. To achieve this, the effect of microwave frequency on the germination of rice seeds was examined. The physiological feedbacks of the MR 219 rice variety in terms of seed germination rate (GR), germination percentage (GP), and mean germination time (MGT) were analyzed by exposing its seeds to 2450 MHz of microwave frequenc...
Erwin
2016-05-01
Full Text Available Aim: The success of a skin graft in a cat is highly dependent on the granulation formed by the base of recipient bed. Granulation by the base of recipient bed will form after several days after injury. This research aimed to observe subjective and objective profile of skin graft recovery on forelimb of cats with different periods of donor skin placement. Materials and Methods: Nine male Indonesian local cats aged 1-2 years old, weighing 3-4 kg were divided into three groups. The first surgery for creating defect wound of 2 cm×2 cm in size was performed in the whole group. The wound was left for several days with the respective interval for each group, respectively: Group I (for 2 days, Group II (for 4 days, and Group III (for 6 days. In the whole group, the second surgery was done by the harvesting skin of thoracic area which then applied on recipient bed of respective groups. Result: The donor skin on Group II was accepted faster compared to Group I and Group III. The donor skin did not show color differences compared to surrounding skin, painless, bright red in bleeding test had faster both hair growth and drug absorption. Test toward the size of donor skin and the effect of drugs did not show a significant difference between each group. Conclusion: The observe subjective and objective profile of skin graft recovery on forelimb of cats on Group II were accepted faster compared to Group I and III.
Existence of Time Periodic Solution of the Hasegawa-Mima Equation%Hasegawa-Mima方程时间周期解的存在性
金珍
2012-01-01
讨论一类带周期边界条件的二维Hasegawa-Mima方程,利用Galerkin方法和Leray-Schaude不动点定理,得到了当外力项f（x,yt,）关于时间t是周期函数时,所得到的解也是时间周期函数。%In this paper, we discuss a 2-dimension Hasegawa-Mima equation with periodic boundary condition. By applying the Galerkin method and Leray-Schauder fixed point theorem, the existence of a time-periodic solution of the Hasegawa-Mima equation is proved when the forcing term.f（ x ,y,t）is periodic function of timer.
Kök, Filiz
2003-01-01
The aim of this study was to investigate the effect of storage time in cumin paste on the microbiological, chemical and sensorial quality of pastırma, a pastrami-like meat product produced from, the Barbel fish, Barbus esocinus. Three groups of pastırma were produced. The groups were kept in cumin paste for 12, 24 and 48 h, respectively. After production, the pastırma was vacuum packed and stored for 90 d at 20 oC. Pastırma samples were analyzed for microbiological counts, moisture rate, pH v...
Shit, Anindita; Chattopadhyay, Sudip; Chaudhuri, Jyotipratim Ray
2013-09-12
Escape from a metastable state in the presence of a high-frequency field (where the driving becomes nonadiabatic) underlies a broad range of phenomena of physics and chemistry, and thus its understanding is of paramount importance. We study the problem of intermediate-to-high-damping escape from a metastable state of a dissipative system driven by a rapidly oscillating field, one of the most important classes of nonequilibrium systems, in a broad range of field driving frequencies (ω) and amplitudes (a). We construct a Langevin equation using quantum gauge transformation in the light of Floquet theorem and exploiting a systematic perturbative expansion in powers of 1/ω using "Kapitza-Landau time window". The quantum dynamics in a high-frequency field are found to be described by an effective time-independent potential. The temperature dependence of escape rate and the change of its form with varying parameters of the field have been analyzed. It may decrease upon increasing the temperature which is contingent on the effects of intricate interplay between external modulation and dissipation. The crossover temperature between tunnelling and thermal hopping increases with an increase in external modulation so that quantum effects in the escape are relevant at higher temperatures. These observations are uncommon and counterintuitive and, therefore, of considerable interest. Our results might be valuable for the exploration of the dynamics of cold atoms in electromagnetic fields. PMID:23627350
LI Shi-ying; SHAO Yu; LI Zheng-dong; LI Li; CHEN Yuan-yuan; CHEN Yi-jiu; HUANG Ping
2012-01-01
The aim of the current study was to investigate the spectra in the different organs of the rats which died of massive hemorrhage; to explore their spectral changes 15 days postmortem and the best mathematical model with different band absorption ratio changes to postmortem interval(PMD; and to compare the spectral changes of different temperature.Thirty male Sprague-Dawley rats were sacrificed by cutting abdominal aorta,and the cadavers were divided equally and kept at 4 ℃,20℃ and 30℃ in the control chamber.From the same rat,seven different organs were sampled at intervals of 1-15 days postmortem,and then measured by Fourier transfom infrared (FTIR) spectrometer.Six mathematical model functions were explored.The absorbance of bands and band absorbance ratios of absorption peak in each organ showed a time-dependent increase or decrease,most band absorbance ratios remaining stable for 7-15 days postmortem.Cubic model functions of the various bands absorbance ratios against PMI showed a stronger related coefficient.The absorbance bands with obvious changes at 20 ℃ showed stabilized tendencies at 4 ℃ and significant changes at 30 ℃ within 15 days postmortem.In addition,FTIR spectroscopy revealed a time-dependent metabolic process,with potential of being used to estimate PMI during 7 days postmortem,which merits further investigation.
Wang, Gang
2014-01-01
ASTROD-GW (ASTROD [Astrodynamical Space Test of Relativity using Optical Devices] optimized for Gravitational Wave detection) is a gravitational-wave mission with the aim of detecting gravitational waves from massive black holes, extreme mass ratio inspirals (EMRIs) and galactic compact binaries, together with testing relativistic gravity and probing dark energy and cosmology. Mission orbits of the 3 spacecrafts forming a nearly equilateral triangular array are chosen to be near the Sun-Earth Lagrange points L3, L4 and L5. The 3 spacecrafts range interferometrically with one another with arm length about 260 million kilometers. For 260 times longer arm length, the detection sensitivity of ASTROD-GW is 260 fold better than that of eLISA/NGO in the lower frequency region by assuming the same acceleration noise. Therefore, ASTROD-GW will be a better cosmological probe. In previous papers, we have worked out the time delay interferometry (TDI) for the ecliptic formation. To resolve the reflection ambiguity about ...
Di Guida, Salvatore
2011-01-01
Automatic, synchronous and of course reliable population of the condition databases is critical for the correct operation of the online selection as well as of the offline reconstruction and analysis of data. In this complex infrastructure, monitoring and fast detection of errors is a very challenging task. To recover the system and to put it in a safe state requires spotting a faulty situation within strict time constraints. We will describe here the system put in place in the CMS experiment to automate the processes that populate centrally the Condition Databases and make condition data promptly available both online for the high-level trigger and offline for reconstruction. The data are automatically collected using centralized jobs or are ``dropped'' by the users in dedicate services (offline and online drop-box), which synchronize them and take care of writing them into the online database. Then they are automatically streamed to the offline database, and thus are immediately acce...
A commonly held perception is that disposal of spent nuclear fuel or high-level waste presents a risk of unprecedented duration. In 40 CFR 191, the EPA requires that projected releases of radioactivity be limited for 10,000 years after disposal with the intent that risks from the disposal repository be no greater than those from the uranium ore deposit from which the nuclear fuel was originally extracted. This study reviews issues involved in assessing compliance with the requirement. The determination of compliance is assumption dependent primarily due to uncertainties in dosi-metric data, and relative availability of the radioactivity for environmental transport and eventual assimilation by humans. A conclusion of this study is that, in time, a spent fuel disposal repository such as the projected Yucca Mountain Project Facility will become less hazardous than the original ore deposit
Francesc MEZQUITA
2010-08-01
Full Text Available Anaesthesia of animals may be useful for different purposes, particularly for veterinary reasons or in experimental research, for manipulation or treatment of immobilized but alive animals. Its use in crustaceans is not uncommon, but it has never been described for Ostracoda. We provide brief and preliminary guidelines on the use of the tricaine mesylate (MS-222 on the widespread freshwater ostracod Eucypris virens and we show that this compound is an effective anaesthetic used as a bath treatment at minimum concentrations of 500 mg L-1. This value is considerably higher than that recommended for other aquatic animals like fish. Recovery time, ranging from 5 to 15 minutes, is mostly determined by anaesthetic bath concentration, while bath duration influenced to a lesser extent. Anaesthesia induced with MS-222 can prove useful for minute manipulation of living ostracods e.g. for identification, marking or image capture under the microscope.
Park, So Yeon; Ahn, Jong Ho; Kim, Yung Il; Kim, Jin Man; Choi, Byung Ki; Pyo, Hong Ryul; Song, Ki Won [Dept. of Radiation Oncology, Samsung Medical Center, Seoul (Korea, Republic of); Suh, Jung Min [Dept. of Radiological Science, Daewon University Colloge, Jecheon (Korea, Republic of)
2012-09-15
It is essential to minimize the movement of tumor due to respiratory movement at the time of respiration controlled radiotherapy of non-small cell lung cancer patient. Accordingly, this Study aims to evaluate the usefulness of restricted respiratory period by comparing and analyzing the treatment plans that apply free and restricted respiration period respectively. After having conducted training on 9 non-small cell lung cancer patients (tumor n=10) from April to December 2011 by using 'signal monitored-breathing (guided- breathing)' method for the 'free respiratory period' measured on the basis of the regular respiratory period of the patents and 'restricted respiratory period' that was intentionally reduced, total of 10 CT images for each of the respiration phases were acquired by carrying out 4D CT for treatment planning purpose by using RPM and 4-dimensional computed tomography simulator. Visual gross tumor volume (GTV) and internal target volume (ITV) that each of the observer 1 and observer 2 has set were measured and compared on the CT image of each respiratory interval. Moreover, the amplitude of movement of tumor was measured by measuring the center of mass (COM) at the phase of 0% which is the end-inspiration (EI) and at the phase of 50% which is the end-exhalation (EE). In addition, both observers established treatment plan that applied the 2 respiratory periods, and mean dose to normal lung (MDTNL) was compared and analyzed through dose-volume histogram (DVH). Moreover, normal tissue complication probability (NTCP) of the normal lung volume was compared by using dose-volume histogram analysis program (DVH analyzer v.1) and statistical analysis was performed in order to carry out quantitative evaluation of the measured data. As the result of the analysis of the treatment plan that applied the 'restricted respiratory period' of the observer 1 and observer 2, there was reduction rate of 38.75% in the 3-dimensional
Garanča, Biruta
2014-01-01
There has been calculated and analysed the profitability of the branches of economy and the basic activity of Latgale in comparison with that of Latvia during the period of time from 2006 to 2012. The impact of the profitability of the economic and the basic activity has been calculated by applying the author’s worked out methodology. There have been calculated and analysed the profitability variation quotients of the branches of economy and the basic activity, which characterize the financia...
Pellicano, E.
2012-01-01
This study investigated the extent and nature of changes in symptomatology in cognitively able children with autism over a 3-year period. Thirty-seven children diagnosed with an autism spectrum condition involved in an earlier study (M age 5 5 years, 7 months) were followed and reassessed 3 years later (M age 5 8 years, 4 months). Scores on the Social Communication Questionnaire (SCQ; M. Rutter, A. Bailey, & C. Lord, 2003) decreased significantly over time in all symptom domains but especiall...
HERWINT SIMBOLON
2005-01-01
A plot of 150x700 m2 was established in a mixed dipterocarps of Wanariset Semboja, East Kalimantan during the periods of 1979-1981. The forest was dominated by Eusideroxylon zwageri (Lauraceae), Dipterocarpus cornutus (Dipterocarpaceae), Pholidocarpus majadum (Arecaceae), and Diospyros borneensis (Ebenaceae). Since the plot establishment, the forests then had experienced three times of forest fires, those were in 1982-1983, 1994-1995 and 1997-1998. The present paper reports the results of re-...
Muhs, Daniel R.; Simmons, Kathleen R.; Steinke, Bree
2002-07-01
The timing and duration of the Last Interglacial period have been controversial, with some studies suggesting a relatively short duration that is orbitally forced and others suggesting a long duration that is at most only partly related to orbital forcing. New, high-precison thermal ionization mass spectrometric (TIMS) U-series ages of Last Interglacial corals from Hawaii and Bermuda test these competing hypotheses. Waimanalo Formation corals from slowly uplifting Oahu, Hawaii range in age from ˜134 to ˜113 ka, with most ages between ˜125 and ˜115 ka. Combined with published U-series ages from nearby Lanai, the data suggest a long Last Interglacial period that may have occurred from ˜136 to at least 115 ka. The results indicate that orbital forcing may not have been the only control on ice sheet growth and decay, because sea level would have been high at times of relatively low Northern Hemisphere summer insolation. On tectonically stable Bermuda, deposits from the ˜200 ka (penultimate interglacial period), ˜120 ka (peak Last Interglacial period) and ˜80 ka (late Last Interglacial period) high sea stands have been newly dated. Fossil corals on Bermuda are derived from patch reefs that likely were "catch-up" responses to sea level rise. It is expected that U-series ages of Last-Interglacial corals on Bermuda should overlap with, but not be as old as the range of corals on Oahu. Last-Interglacial corals on Bermuda give a range of ˜125-113 ka, which supports this hypothesis. A large number of emergent marine deposits on Hawaii, Bermuda and along coastal North America have now been dated to the Last Interglacial period. Both Oahu and Bermuda have marine invertebrate faunas with a number of extralimital southern species of mollusks, suggesting warmer-than-present waters during the Last Interglacial period. Warmer waters are also suggested for Last-Interglacial localities around most of North America, from Florida to Canada and Greenland and Baja California to
Automatic, synchronous and reliable population of the condition databases is critical for the correct operation of the online selection as well as of the offline reconstruction and analysis of data. In this complex infrastructure, monitoring and fast detection of errors is a very challenging task. In this paper, we describe the CMS experiment system to process and populate the Condition Databases and make condition data promptly available both online for the high-level trigger and offline for reconstruction. The data are automatically collected using centralized jobs or are 'dropped' by the users in dedicated services (offline and online drop-box), which synchronize them and take care of writing them into the online database. Then they are automatically streamed to the offline database, and thus are immediately accessible offline worldwide. The condition data are managed by different users using a wide range of applications. In normal operation the database monitor is used to provide simple timing information and the history of all transactions for all database accounts, and in the case of faults it is used to return simple error messages and more complete debugging information.
Quantum 3D spin-glass system on the scales of space-time period of external electromagnetic field
Full text: (author)The quantum 3D spin-glass system was investigated under the influence of external electromagnetic fields. Using Birgoff ergodic hypothesis the considered problem was reduced on two conditionally separable 1D problems. The first 1D problem describes N-body disordered quantum system on the space-time scales of external fields, with taking into account relaxation effects in the environment. Mathematically the problem is formulated in the limits of stochastic differential equation (SDE) for complex probabilistic processes. Using SDE type of Langevin-Schrodinger for the quantum distribution partial differential equation of second order is obtained. The second problem describes ensemble of 1D steric spin-chains with the certain length which are interacting randomly. For the description of this ensemble the system of the algebraic equations is obtained. These equations allows to build stable spin-chains and correspondingly to calculate statistical sum of ensemble at equilibrium. It is shown that combining of these two problems allows investigating 3D quantum spin-glass system along the external fields' propagation. In particular to investigate collective orientational effects which can leads to phase transitions of the first order and the order formation in disordered 3D quantum system
We investigate numerically the effects of time delay on the phenomenon of noise-enhanced stability (NES) in a periodically modulated bistable system. Three types of time-delayed feedback, including linear delayed feedback, nonlinear delayed feedback and global delayed feedback, are considered. We find a non-monotonic behaviour of the mean first-passage time (MFPT) as a function of the delay time τ, with a maximum in the case of linear delayed feedback and with a minimum in the case of nonlinear delayed feedback. There are two peculiar values of τ around which the NES phenomenon is enhanced or weakened. For the case of global delayed feedback, the increase of τ always weakens the NES phenomenon. Moreover, we also show that the amplitude A and the frequency Ω of the periodic forcing play an opposite role in the NES phenomenon, i.e. the increase of A weakens the NES effect while the increase of Ω enhances it. These observations demonstrate that the time-delayed feedback can be used as a feasible control scheme for the NES phenomenon
Maggi, F.; Gu, C.; Venterea, R.; Riley, W.; Oldenburg, C.
2007-12-01
The biogeochemical cycle of nitrogen and production of NO, N2O, and CO2 gas and NO2- and NO3- ions in nutrient-enriched agricultural fields is mediated by soil microbial activity, the hydrological cycle, plant dynamics, and climatic forcing. Understanding how NO, N2O, CO2 gases and NO2- and NO3- ions are released from agricultural fields to the environment is a key factor in controlling the green-house effect and water contamination, and assumes ever greater importance in view of the foreseen increase in biofuel, food, and fiber production. To address these issues we have developed a mechanistic model (TOUGHREACT-N) for various nitrification and denitrification pathways, multiple microbial biomass dynamics, heat and water flows, and various chemical reactions at local and kinetic equilibrium. The soil column is represented in a 1D framework, with hydraulic properties described by a water tension-saturation model. Biotic and abiotic reactions are assumed to follow Michaelis-Menten kinetics, while a consortium of several micro-organismal strains is assumed to follow multiple Monod growth kinetics accounting for electron donor, electron acceptor, and inhibitor concentrations. Water flow is modeled with the Darcy-Richards equation, while nutrient transport is modeled by Fickian advective and diffusive processes in both gaseous and liquid phases. Heat flow is modeled with the Fourier equation. Plant dynamics is taken into account by coupling TOUGHREACT-N with CERES to determine water and nutrient uptake, and soil carbon accumulation. TOUGHREACT-N was calibrated against field measurements to assess pathways of N losses following fertilization. A good agreement between field observations and model predictions was found. We identified two dominant time scales in the system response that depended on plants dynamics. Before plants have substantial impact on soil nutrients and moisture content, N losses are characterized by rapid increases as a function of water application
In this paper, a residual life-time assessment of the 110 MW boiler reheater components is presented. Real operational conditions for each reheater component as a basis for the life-time assessment are experimentally determined with specially designed diagnostic and data acquisition system during five different regimes of boiler operation. According to determined operational conditions compared with the respective properties of reheater components, two main conclusions are done: (a) more than 60% of the real life-time is spent and (b) a shorter life-time than it is designed could be expected for the several components of reheater system. Taking these conclusions into account, a preposition of measures to be taken in order to obtain satisfied reliability of reheater system in the future period are recommended. One of proposed measures is to obtain respective monitoring equipment [12] for the boiler reheater system. (Author)
Lorimer, D R; Manchester, R N; Possenti, A; Lyne, A G; McLaughlin, M A; Kramer, M; Hobbs, G; Stairs, I H; Burgay, M; Eatough, R P; Keith, M J; Faulkner, A J; D'Amico, N; Camilo, F; Corongiu, A; Crawford, F
2015-01-01
We present timing observations of four millisecond pulsars discovered in the Parkes 20-cm multibeam pulsar survey of the Galactic plane. PSRs J1552-4937 and J1843-1448 are isolated objects with spin periods of 6.28 and 5.47 ms respectively. PSR J1727-2946 is in a 40-day binary orbit and has a spin period of 27 ms. The 4.43-ms pulsar J1813-2621 is in a circular 8.16-day binary orbit around a low-mass companion star with a minimum companion mass of 0.2 solar masses. Combining these results with detections from five other Parkes multibeam surveys, gives a well-defined sample of 56 pulsars with spin periods below 20 ms. We develop a likelihood analysis to constrain the functional form which best describes the underlying distribution of spin periods for millisecond pulsars. The best results were obtained with a log-normal distribution. A gamma distribution is less favoured, but still compatible with the observations. Uniform, power-law and Gaussian distributions are found to be inconsistent with the data. Galactic...
Giulia Carreras
2013-12-01
Full Text Available This study aimed to describe past time trends of the prevalence of former smokers in Italy and to estimate prevalence projections using a Bayesian approach. An age-period-cohort (APC analysis has been carried out in order to investigate the effect of the age, period and birth cohort on the prevalence of former smokers during 1980–2009. A Bayesian APC model with an autoregressive structure for the age, period and cohort parameters has been used to estimate future trends. Results showed that awareness of harm from smoking occurred at younger ages with each advancing cohort, and that women were more likely to attempt to stop smoking during pregnancies and breastfeeding, whereas men attempted to quit only when smoking-related diseases became evident. Projections of future trend recorded a further increase in the number of former smokers in future decades, showing an estimate of the “end of smoking” around years 2060 and 2055 in men and women, respectively. The application of the APC analysis to study the prevalence of former smokers turned out to be a useful method for the evaluation of past smoking trends, reflecting the effects of tobacco control policies on time and generations, and to make projections of future trend.
Analyses of phenomena exhibiting finite-time decay of quantum entanglement have recently attracted considerable attention. Such decay is often referred to as sudden vanishing (or sudden death) of entanglement, which can be followed by its sudden reappearance (or sudden rebirth). We analyze various finite-time decays (for dissipative systems) and analogous periodic vanishings (for unitary systems) of nonclassical correlations as described by violations of classical inequalities and the corresponding nonclassicality witnesses (or quantumness witnesses), which are not necessarily entanglement witnesses. We show that these sudden vanishings are universal phenomena and can be observed: (i) not only for two- or multimode but also for single-mode nonclassical fields, (ii) not solely for dissipative systems, and (iii) at evolution times which are usually different from those of sudden vanishings and reappearances of quantum entanglement.
Measurement of oxygen-15- (15O) water uptake with positron emission tomography (PET) is a sensitive technique to monitor regional brain activation secondary to stimulation paradigms. In order to investigate data acquisition times that show maximal changes in regional activation and to assess the optimal time for stimulus presentation, we investigated 10 controls with 15O-water and PET during baseline and stroboscopic light stimulation. Sequential scans were done varying the time of stimulus presentation. The images were reconstructed using three different periods of data acquisition: uptake phase (initial 30-35 sec), washout phase (40 sec following peak activity in brain), and total activity (3 min). The images reconstructed during the uptake phase showed the largest changes in occipital cortex from stimulation. Maximal changes in occipital cortex were obtained when the visual stimulus was maintained during the uptake phase only
El Aroudi A.
2014-01-01
Full Text Available In this paper closed-form conditions for predicting the boundary of period-doubling (PD bifurcation or saddle-node (SN bifurcation in a class of PWM piecewise linear systems are obtained from a time-domain asymptotic approach. Examples of switched system considered in this study are switching dc-dc power electronics converters, temperature control systems and hydraulic valve control systems among others. These conditions are obtained from the steady-state discrete-time model using an asymptotic approach without resorting to frequency-domain Fourier analysis and without using the monodromy or the Jacobian matrix of the discrete-time model as it was recently reported in the existing literature on this topic. The availability of such design-oriented boundary expressions allows to understand the effect of the different parameters of the system upon its stability and its dynamical behavior.
Mahata, Gour Chandra
2015-03-01
In practice, the supplier often offers the retailers a trade credit period and the retailer in turn provides a trade credit period to her/his customer to stimulate sales and reduce inventory. From the retailer's perspective, granting trade credit not only increases sales and revenue but also increases opportunity cost (i.e., the capital opportunity loss during credit period) and default risk (i.e., the percentage that the customer will not be able to pay off his/her debt obligations). Hence, how to determine credit period is increasingly recognized as an important strategy to increase retailer's profitability. Also, the selling items such as fruits, fresh fishes, gasoline, photographic films, pharmaceuticals and volatile liquids deteriorate continuously due to evaporation, obsolescence and spoilage. In this paper, we propose an economic order quantity model for the retailer where (1) the supplier provides an up-stream trade credit and the retailer also offers a down-stream trade credit, (2) the retailer's down-stream trade credit to the buyer not only increases sales and revenue but also opportunity cost and default risk, and (3) the selling items are perishable. Under these conditions, we model the retailer's inventory system as a profit maximization problem to determine the retailer's optimal replenishment decisions under the supply chain management. We then show that the retailer's optimal credit period and cycle time not only exist but also are unique. We deduce some previously published results of other researchers as special cases. Finally, we use some numerical examples to illustrate the theoretical results.
Moschen, R.; Kühl, N.; Peters, S.; Vos, H.; Lücke, A.
2011-09-01
This paper presents a high resolution reconstruction of local growing season temperature (GST) anomalies at Dürres Maar, Germany, spanning the last two millennia. The GST anomalies were derived from a stable carbon isotope time series of cellulose chemically extracted from Sphagnum leaves (δ13Ccellulose) separated from a kettle-hole peat deposit of several metres thickness. The temperature reconstruction is based on the Sphagnum δ13Ccellulose/temperature dependency observed in calibration studies. Reconstructed GST anomalies show considerable centennial and decadal scale variability. A cold and presumably wet phase with below-average temperature is reconstructed between the 4th and 7th century AD which is in accordance with the so called European Migration Period, marking the transition from the Late Roman Period to the Early Middle Ages. At High Medieval Times, the amplitude in the reconstructed temperature variability is most likely overestimated; nevertheless, above-average temperatures are obvious during this time span, which are followed by a temperature decrease. On the contrary, a pronounced Late Roman Climate Optimum, often described as similarly warm or even warmer as medieval times, could not be detected. The temperature signal of the Little Ice Age (LIA) is not preserved in Dürres Maar due to considerable peat cutting that takes place in the first half of the 19th century. The local GST anomalies show a remarkable agreement to northern hemispheric temperature reconstructions based on tree-ring datasets and are also in accordance with climate reconstructions on the basis of lake sediments, glacier advances and retreats, and historical datasets. Most notably, e.g., during the Early Middle Ages and at High Medieval Times, temperatures were neither low nor high in general. Rather high frequency temperature variability with multiple narrow intervals of below- and above-average temperatures at maximum lasting a few decades are reconstructed. Especially the
The pattern of carbon-14 (C-14) distribution among parts of rice growing in the vicinity of the Korean CANDU plant during the growth period was investigated. Six-time samplings of rice and air were performed in seven fields from rice planting to harvest, and the measurements of C-14 content were made by using liquid scintillation counter on the air and each of available parts of the rice such as root, stem, crust and ear. The results illustrated that C-14 showed a relatively even distribution among parts of rice during the growth period implying C-14 accumulation was more dependent on interactions among the parts such as transportation of nutrients than on photosynthesis occurring only in stem that has chlorophyll. Also it was observed that the difference of C-14 concentration between each part of rice and the air decreased with time indicating that the time was needed for C-14 to reach equilibrium between both sides. The radius within which C-14 released from the Wolsong plant could have a significant effect on the C-14 concentrations of the parts was observed to be about 5 km. (author)
Ganesh S
2016-01-01
Full Text Available Sri Ganesh, Sheetal BrarDepartment of Phaco and Refractive Surgeries, Nethradhama Superspeciality Eye Hospital, Bangalore, IndiaPurpose: To compare the effect of two ocular viscosurgical devices (OVDs on intraocular pressure (IOP and surgical time in immediate postoperative period after bilateral implantable collamer lens (using the V4c model implantation.Methods: A total of 20 eligible patients were randomized to receive 2% hydroxypropylmethylcellulose (HPMC in one eye and 1% hyaluronic acid in fellow eye. Time taken for complete removal of OVD and total surgical time were recorded. At the end of surgery, IOP was adjusted between 15 and 20 mmHg in both the eyes.Results: Mean time for complete OVD evacuation and total surgical time were significantly higher in the HPMC group (P=0.00. Four eyes in the HPMC group had IOP spike, requiring treatment. IOP values with noncontact tonometry at 1, 2, 4, 24, and 48 hours were not statistically significant (P>0.05 for both the groups.Conclusion: The study concluded that 1% hyaluronic acid significantly reduces total surgical time, and incidence of acute spikes may be lower compared to 2% HPMC when used for implantable collamer lens (V4c model.Keywords: OVD, hyaluronic acid, ICL, V4c, IOP spikes
Baluev, Roman V.
2013-11-01
This is a parallelized algorithm performing a decomposition of a noisy time series into a number of sinusoidal components. The algorithm analyses all suspicious periodicities that can be revealed, including the ones that look like an alias or noise at a glance, but later may prove to be a real variation. After the selection of the initial candidates, the algorithm performs a complete pass through all their possible combinations and computes the rigorous multifrequency statistical significance for each such frequency tuple. The largest combinations that still survived this thresholding procedure represent the outcome of the analysis.
Krainev, M B; Kalinin, M S; Svirzhevskaya, A K; Svirzhevsky, N S
2014-01-01
Using the simple model for the description of the GCR modulation in the heliosphere and the sets of parameters discussed in the accompanying paper we model some features of the time and energy behavior of the GCR intensity near the Earth observed during periods of low solar activity around three last solar minima. In order to understand the mechanisms underlying these features in the GCR behavior, we use the suggested earlier decomposition of the calculated intensity into the partial intensities corresponding to the main processes (diffusion, adiabatic losses, convection and drifts).
Tsirogiannis, George A.; Davis, Kathryn E.
2016-07-01
The proposed method connects two unstable periodic orbits by employing trajectories of their associated invariant manifolds that are perturbed in two levels. A first level of velocity perturbations is applied on the trajectories of the discretized manifolds at the points where they approach the nominal unstable periodic orbit in order to accelerate them. A second level of structured velocity perturbations is applied to trajectories that have already been subjected to first level perturbations in order to approximately meet the necessary conditions for a low Δ {V} transfer. Due to this two-level perturbation approach, the number of the trajectories obtained is significantly larger compared with approaches that employ traditional invariant manifolds. For this reason, the problem of connecting two unstable periodic orbits through perturbed trajectories of their manifolds is transformed into an equivalent discrete optimization problem that is solved with a very low computational complexity algorithm that is proposed in this paper. Finally, the method is applied to a lunar observation mission of practical interest and is found to perform considerably better in terms of Δ {V} cost and time of flight when compared with previous techniques applied to the same project.
Quero, G.; Severino, R.; Vaiano, P.; Consales, M.; Ruvo, M.; Sandomenico, A.; Borriello, A.; Giordano, M.; Zuppolini, S.; Diodato, L.; Cutolo, A.; Cusano, A.
2015-09-01
We report the development of a reflection-type long period fiber grating (LPG) biosensor able to perform the real time detection of thyroid cancer markers in the needle washout of fine-needle aspiration biopsy. A standard LPG is first transformed in a practical probe working in reflection mode, then it is coated by an atactic-polystyrene overlay in order to increase its surrounding refractive index sensitivity and to provide, at the same time, the desired interfacial properties for a stable bioreceptor immobilization. The results provide a clear demonstration of the effectiveness and sensitivity of the developed biosensing platform, allowing the in vitro detection of human Thyroglobulin at sub-nanomolar concentrations.
Periodic functions with variable period
Pryjmak, M. V
2010-01-01
The examples of rhythmical signals with variable period are considered. The definition of periodic function with the variable period is given as a model of such signals. The examples of such functions are given and their variable periods are written in the explicit form. The system of trigonometric functions with the variable period is considered and its orthogonality is proved. The generalized system of trigonometric functions with the variable period is also suggested; some conditions of it...
The clinical predictors of aromatase inhibitor-related arthralgia (AIA), a drug-related adverse reaction of aromatase inhibitors (AIs), remain unclear. AIA was prospectively surveyed every 4 months in 328 postmenopausal breast cancer patients administered a non-steroidal AI (anastrozole). Various clinicopathological parameters were recorded and analyzed (chi-square test, Fisher's exact test and logistic regression analysis). The mean observation period was 39.9 months. AIA manifested in 114 patients (34.8%), with peaks of onset at 4 (33.7%) and 8 months (11.4%) after starting AI administration. Some cases manifested even after 13 months. AIA tended to occur in younger patients (incidences of 46.3%, 37.4% and 28.0% for ages of < 55, 55-65 and > 65 years, respectively (p = 0.063)) and decreased significantly with the age at menarche (53.3%, 35.3% and 15.4% for < 12, 12-15 and > 15 years, respectively (p = 0.036)). The incidences were 45.1%, 46.3 and 25.1% for the time since the last menstrual period (LMP) < 5 years, 5-10 years and > 10 years, being significantly lower at > 10 years (p < 0.001). In logistic regression analysis, the AIA incidence was significantly lower in the time since LMP > 10-year group versus the < 5-year group (odds ratio 0.44, p = 0.002), but the age at menarche showed no association. AIA manifested significantly earlier (≤ 6 months) as the time since LMP became shorter (< 5 years). AIA tends to manifest early after starting AI, but some cases show delayed onset. The incidence was significantly lower in patients with a duration of > 10 years since LMP. When the time since LMP was short, the onset of AIA was significantly earlier after starting AI administration
Fujiwara, A.; Hirawake, T.; Suzuki, K.; Eisner, L.; Imai, I.; Nishino, S.; Kikuchi, T.; Saitoh, S.-I.
2016-01-01
The size structure and biomass of a phytoplankton community during the spring bloom period can affect the energy use of higher-trophic-level organisms through the predator-prey body size relationships. The timing of the sea ice retreat (TSR) also plays a crucial role in the seasonally ice-covered marine ecosystem, because it is tightly coupled with the timing of the spring bloom. Thus, it is important to monitor the temporal and spatial distributions of a phytoplankton community size structure. Prior to this study, an ocean colour algorithm was developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a (chl a) derived from cells larger than 5 µm to the total chl a, using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analysed the pixel-by-pixel relationships between FL during the marginal ice zone (MIZ) bloom period and TSR over the period of 1998-2013. The influences of the TSR on the sea surface temperature (SST) and changes in ocean heat content (ΔOHC) during the MIZ bloom period were also investigated. A significant negative relationship between FL and the TSR was widely found in the shelf region during the MIZ bloom season. However, we found a significant positive (negative) relationship between the SST (ΔOHC) and TSR. Specifically, an earlier sea ice retreat was associated with the dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that the duration of the nitrate supply, which is important for the growth of large-sized phytoplankton in this region (i.e. diatoms), can change according to the TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns as a result of an increase in solar radiation toward the summer solstice. Moreover, we found that both the length of the ice-free season
A. Lücke
2011-09-01
Full Text Available This paper presents a high resolution reconstruction of local growing season temperature (GST anomalies at Dürres Maar, Germany, spanning the last two millennia. The GST anomalies were derived from a stable carbon isotope time series of cellulose chemically extracted from Sphagnum leaves (δ13Ccellulose separated from a kettle-hole peat deposit of several metres thickness. The temperature reconstruction is based on the Sphagnum δ13Ccellulose/temperature dependency observed in calibration studies. Reconstructed GST anomalies show considerable centennial and decadal scale variability. A cold and presumably wet phase with below-average temperature is reconstructed between the 4th and 7th century AD which is in accordance with the so called European Migration Period, marking the transition from the Late Roman Period to the Early Middle Ages. At High Medieval Times, the amplitude in the reconstructed temperature variability is most likely overestimated; nevertheless, above-average temperatures are obvious during this time span, which are followed by a temperature decrease. On the contrary, a pronounced Late Roman Climate Optimum, often described as similarly warm or even warmer as medieval times, could not be detected. The temperature signal of the Little Ice Age (LIA is not preserved in Dürres Maar due to considerable peat cutting that takes place in the first half of the 19th century. The local GST anomalies show a remarkable agreement to northern hemispheric temperature reconstructions based on tree-ring datasets and are also in accordance with climate reconstructions on the basis of lake sediments, glacier advances and retreats, and historical datasets. Most notably, e.g., during the Early Middle Ages and at High Medieval Times, temperatures were neither low nor high in general. Rather high frequency temperature variability with multiple narrow intervals of below- and above-average temperatures at maximum lasting a few decades are
Baluev, Roman V
2013-01-01
This is a parallelized algorithm performing a decomposition of a noisy time series into a number of frequency components. The algorithm analyses all suspicious periodicities that can be revealed, including the ones that look like an alias or noise at a glance, but later may prove to be a real variation. After selection of the initial candidates, the algorithm performs a complete pass through all their possible combinations and computes the rigorous multi-frequency statistical significance for each such frequency tuple. The largest combinations that still survived this thresholding procedure represent the outcome of the analysis. The parallel computing on a graphics processing unit (GPU) is implemented through CUDA and brings a significant performance increase. It is still possible to run FREDEC solely on CPU in the traditional single-threaded mode, when no suitable GPU device is available.
R. Moschen
2011-02-01
Full Text Available This paper presents a high resolution reconstruction of local growing season temperature (GST anomalies at Dürres Maar, Germany, spanning the last two millennia. The GST anomalies were derived from a stable carbon isotope time series of cellulose chemically extracted from Sphagnum leaves (δ^{13}C_{cellulose} separated from a kettle-hole peat deposit of several metres thickness. The temperature reconstruction is based on the Sphagnum δ^{13}C_{cellulose} /temperature dependency observed in calibration studies. Reconstructed GST anomalies show considerable centennial and decadal scale variability. A cold and presumably also wet phase with below-average temperature is reconstructed between the 4th and 7th century AD which is in accordance with the so called European Migration Period marking the transition from the Late Roman Period to the Early Middle Ages. At High Medieval Times above-average temperatures are obvious followed by a temperature decrease. On the contrary, a pronounced Late Roman Climate Optimum, often described as similar warm or even warmer as medieval times, could not be detected. The temperature signal of the Little Ice Age (LIA is not preserved in Dürres Maar due to considerable peat cutting that takes place in the first half of the 19th century. The local GST anomalies show a remarkable agreement to northern hemispheric temperature reconstructions based on tree-ring data sets and are also in accordance with climate reconstructions on the basis of lake sediments, glacier advances and retreats, and historical data sets. Most notably, e.g. during the Early Middle Ages and at High Medieval Times, temperatures were not low or high in general. Rather high frequency temperature variability with multiple narrow intervals of below- and above-average temperatures at maximum lasting a few decades are reconstructed. Especially the agreements between our estimated GST anomalies and the NH
HERWINT SIMBOLON
2005-04-01
Full Text Available A plot of 150x700 m2 was established in a mixed dipterocarps of Wanariset Semboja, East Kalimantan during the periods of 1979-1981. The forest was dominated by Eusideroxylon zwageri (Lauraceae, Dipterocarpus cornutus (Dipterocarpaceae, Pholidocarpus majadum (Arecaceae, and Diospyros borneensis (Ebenaceae. Since the plot establishment, the forests then had experienced three times of forest fires, those were in 1982-1983, 1994-1995 and 1997-1998. The present paper reports the results of re-measurement of some 150x110 m2 parts of the plot in August 2003, about 23 years after plot establishment. Micro topographically, the studied plot was relatively undulating in higher parts and relatively flat in the lower parts of the plot, while the differences between lowest sub-plot and higher sub-plot of the re-measured plot was 26 m. Forest floor of the lower parts of the plot were humid to wet during rainy season and still humid during dry season. Almost all of the trees within lower parts of the plot were escaped from these three times of forest fires; hence these sub-plots were dominated by the trees of primary species that enumerated in 1980. Those sub-plots in the higher parts were burnt during the past forest fires indicated by the charcoal of standing trees and remaining felling logs in the forest floor. These burnt sub-plots were dominated by pioneer or secondary tree species, such as: Mallotus spp., Macaranga spp., Ficus spp. and Vernonia arborea. Local distribution of some indicator species (such as primary tree species: Pholidocarpus majadum, Diospyros spp., Eusideroxylon zwageri and species of Dipterocarpaceae; pioneer or secondary tree species Vernonia arborea, Macaranga spp., Mallotus spp., Ficus uncinulata, Piper aduncum, Peronema canescens within the plot were figured. Mortality, recruitment and growth rate during the period of 1980-2003 were also discussed.
Goldberg, Richard A.; Feofilov, Artem G.; Kutepov, Alexander A.; Pesnell W. Dean; Schmidlin, Francis J.
2011-01-01
In July, 2002, the MaCWAVE-MIDAS Rocket Program was launched from Andoya Rocket Range (ARR) in Norway. Data from these flights demonstrated that the polar summer mesosphere during this period was unusual, at least above ARR. Theoretical studies have since been published that imply that the abnormal characteristics of this polar summer were generated by dynamical processes occurring in the southern polar winter hemisphere. We have used data from the SABER instrument aboard the NASA Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) Satellite to study these characteristics and compare them with the features observed in the ensuing eight years. For background, the TIMED Satellite was launched on December 7,2001 to study the dynamics and energy of the mesosphere and lower thermosphere. The SABER instrument is a limb scanning infrared radiometer designed to measure temperature of the region as well as a large number of minor constituents. In this study, we review the MaCWAVE rocket results. Next, we investigate the temperature characteristics of the polar mesosphere as a function of spatial and temporal considerations. We have used the most recent SABER dataset (1.07). Weekly averages are used to make comparisons between the winter and summer hemispheres. Furthermore, the data analysis agrees with recent theoretical studies showing that this behavior is a result of anomalous dynamical events in the southern hemisphere. The findings discussed here clearly show the value of scientific rocket flights used in a discovery mode.
A condition for the existence of a periodic TDHF trajectory of period T is derived. It takes a from very similar to the static H.F. equation and shows that associated to a periodic trajectory there is a static single particle hamiltonian which is a complicated functional of the time dependent density matrix. An explicit expansion for this functional is derived. It is shown that many properties of the static H.F. rest point are shared by periodic solutions. (Author)
Versini, P.-A.; Petrucci, G.; de Gouvello, B.
2014-09-01
Experimental green-roof rainfall-runoff observations have shown a positive impact on stormwater management at the building scale; with a decrease in the peak discharge and a decrease in runoff volume. This efficiency of green-roofs varies from one rainfall event to another depending on precipitation characteristics and substrate antecedent conditions. Due to this variability, currently, green-roofs are rarely officially used as a regulation tool to manage stormwater. Indeed, regulation rules governing the connection to the stormwater network are usually based on absolute threshold values that always have to be respected: maximum areal flow-rate or minimum retention volume for example. In this context, the aim of this study is to illustrate how a green-roof could represent an alternative to solve stormwater management issues, if the regulation rules were further based on statistics. For this purpose, a modelling scheme has been established at the parcel scale to simulate the hydrological response of several roof configurations: impervious, strictly regulated (in terms of areal flow-rate or retention volume), and covered by different types of green-roof matter. Simulations were carried out on a long precipitation time period (23 years) that included a large and heterogeneous set of hydrometeorological conditions. Results obtained for the different roof configurations were compared. Based on the return period of the rainfall event, the probability to respect some regulation rules (defined from real situations) was assessed. They illustrate that green-roofs reduce stormwater runoff compared to an impervious roof surface and can guarantee the respect of the regulation rules in most of the cases. Moreover, their implementation can appear more realistic than that of other infrastructures strictly complying with regulations and demanding significant storage capacity.
Yatan Pal Singh Balhara
2016-01-01
Full Text Available Background: Cannabis continues to be the most commonly used illicit psychoactive substance globally. The National Survey in India conducted in the year 2004 also reported it to be the most commonly used illicit substance in the country. Furthermore, it was reported to be the second most commonly used psychoactive substance by the treatment seekers at de-addiction centers in the country. Objectives: To assess time trends of cannabis use among treatment-seeking individuals at government de-addiction centers across India over a period of 7 years. Materials and Methods: The study utilized data collected through Drug Abuse Monitoring System across India. The data of treatment seekers from de-addiction centers established under the Drug De-addiction Program, Ministry of Health and Family Welfare, Government of India and supported by the Ministry of Social Justice and Empowerment, Government of India (122 in number across the country were analyzed. Results: A total of 107,469 individuals sought treatment from government de-addiction centers over the 7 years (2007–2013 period. With the exception of an aberration for the year 2012, there has been a steady decline in the proportion of treatment seekers who are not current cannabis users. A significantly greater proportion (Chi-square: 586.30, df: 1, P < 0.001 of individuals with current cannabis use alone or along with tobacco (20.4% tend to have a co-morbid psychiatric disorder as compared to treatment seekers with current use of substances other than cannabis (6.1%. Conclusions: It is important to focus on cannabis in clinical service delivery and research in the country.
Fujiwara, A.; Hirawake, T.; Suzuki, K.; Eisner, L.; Imai, I.; Nishino, S.; Kikuchi, T.; Saitoh, S. I.
2015-08-01
Timing of sea ice retreat (TSR) as well as cell size of primary producers (i.e., phytoplankton) plays crucial roles in seasonally ice-covered marine ecosystem. Thus, it is important to monitor the temporal and spatial distribution of phytoplankton community size structure. Prior to this study, an ocean color algorithm has been developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a derived from the cells larger than 5 μm to the total chl a using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analyzed pixel-by-pixel relationships between FL during marginal ice zone (MIZ) bloom period and TSR over a period of 1998-2013. The influence of TSR on sea surface temperature (SST) and changes in ocean heat content (ΔOHC) during the MIZ bloom period were also investigated. A significant negative relationship between FL and TSR was widely found in the shelf region during MIZ bloom season. On the other hand, we found a significant positive (negative) relationship between SST (ΔOHC) and TSR. That is, earlier sea-ice retreat was associated with a dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that duration of nitrate supply, which is important for large-sized phytoplankton growth in this region (i.e., diatoms), can change according to TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns due to an increase in solar radiation toward the summer solstice. Moreover, we found not only the length of ice-free season but also annual median of FL positively correlated with annual net primary production (APP). Thus, both phytoplankton community composition and growing season are important for APP in the study area. Our findings showed quantitative relationship between the inter-annual variability of FL
A. Fujiwara
2015-08-01
Full Text Available Timing of sea ice retreat (TSR as well as cell size of primary producers (i.e., phytoplankton plays crucial roles in seasonally ice-covered marine ecosystem. Thus, it is important to monitor the temporal and spatial distribution of phytoplankton community size structure. Prior to this study, an ocean color algorithm has been developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a derived from the cells larger than 5 μm to the total chl a using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analyzed pixel-by-pixel relationships between FL during marginal ice zone (MIZ bloom period and TSR over a period of 1998–2013. The influence of TSR on sea surface temperature (SST and changes in ocean heat content (ΔOHC during the MIZ bloom period were also investigated. A significant negative relationship between FL and TSR was widely found in the shelf region during MIZ bloom season. On the other hand, we found a significant positive (negative relationship between SST (ΔOHC and TSR. That is, earlier sea-ice retreat was associated with a dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that duration of nitrate supply, which is important for large-sized phytoplankton growth in this region (i.e., diatoms, can change according to TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns due to an increase in solar radiation toward the summer solstice. Moreover, we found not only the length of ice-free season but also annual median of FL positively correlated with annual net primary production (APP. Thus, both phytoplankton community composition and growing season are important for APP in the study area. Our findings showed quantitative relationship between the inter
van den Eijnden, Jakob; Ingram, Adam; Uttley, Phil
2016-06-01
We present a model-independent analysis of the short-time-scale energy dependence of low-frequency quasi-periodic oscillations (QPOs) in the X-ray flux of GRS 1915+105. The QPO frequency in this source has previously been observed to depend on photon energy, with the frequency increasing with energy for observations with a high (≳2 Hz) QPO frequency, and decreasing with energy for observations with a low (≲2 Hz) QPO frequency. As this observed energy dependence is currently unexplained, we investigate if it is intrinsic to the QPO mechanism by tracking phase lags on (sub)second time-scales. We find that the phase lag between two broad energy bands systematically increases for 5-10 QPO cycles, after which the QPO becomes decoherent, the phase lag resets and the pattern repeats. This shows that the band with the higher QPO frequency is running away from the other band on short time-scales, providing strong evidence that the energy dependence of the QPO frequency is intrinsic. We also find that the faster the QPO decoheres, the faster the phase lag increases, suggesting that the intrinsic frequency difference contributes to the decoherence of the QPO. We interpret our results within a simple geometric QPO model, where different radii in the inner accretion flow experience Lense-Thirring precession at different frequencies, causing the decoherence of the oscillation. By varying the spectral shape of the inner accretion flow as a function of radius, we are able to qualitatively explain the energy-dependent behaviour of both QPO frequency and phase lag.
Ru Giuseppe
2009-09-01
Full Text Available Abstract Background The Age-Period-Cohort (APC analysis is routinely used for time trend analysis of cancer incidence or mortality rates, but in veterinary epidemiology, there are still only a few examples of this application. APC models were recently used to model the French epidemic assuming that the time trend for BSE was mainly due to a cohort effect in relation to the control measures that may have modified the BSE exposure of cohorts over time. We used a categorical APC analysis which did not require any functional form for the effect of the variables, and examined second differences to estimate the variation of the BSE trend. We also reanalysed the French epidemic and performed a simultaneous analysis of Italian data using more appropriate birth cohort categories for comparison. Results We used data from the exhaustive surveillance carried out in France and Italy between 2001 and 2007, and comparatively described the trend of the epidemic in both countries. At the end, the shape and irregularities of the trends were discussed in light of the main control measures adopted to control the disease. In Italy a decrease in the epidemic became apparent from 1996, following the application of rendering standards for the processing of specific risk material (SRM. For the French epidemic, the pattern of second differences in the birth cohorts confirmed the beginning of the decrease from 1995, just after the implementation of the meat and bone meal (MBM ban for all ruminants (1994. Conclusion The APC analysis proved to be highly suitable for the study of the trend in BSE epidemics and was helpful in understanding the effects of management and control of the disease. Additionally, such an approach may help in the implementation of changes in BSE regulations.
Mariana Pires Crespo
2013-10-01
Full Text Available PURPOSE: To evaluate the effects of coronal leakage on concentration of hydrogen ions (pH and calcium release of several calcium hydroxide pastes, over different periods of time. MATERIAL AND METHODS: Fifty extracted human mandibular central incisors (n=10 were instrumented up to the F2 instrument and assigned to the following intracanal dressing: G1- Calen, G2- Calen with 0.4% chlorhexidine (CHX, G3- Calcium hydroxide with camphorated paramonochlorophenol (CPMC and glycerin, G4- Calen, but temporary filling material maintained during all test (positive control and G5- Root canal without intracanal dressing (negative control. All groups were immersed in distilled water for 7 days. In sequence, the temporary filling materials were removed, except in controls groups. All specimens were individually mounted on a specific device and only its root again immersed in distilled water. Concentration of hydrogen ions and calcium release by calcium hydroxide pastes in distilled water were evaluated in 24h, 7, 14 and 28 days. The results were submitted to ANOVA test (p = 0.05. After 28 days, root canals from experimental groups were examined in SEM. RESULTS: G1, G2, G3 and G4 presented similar pH values and calcium release and did not differ from each other (p>0.05, up to 7 days. After this time G1, G2 and G3 presented values lower values than G4 (p<0.05. In SEM analysis, calcium hydroxide residues were observed in all experimental groups. CONCLUSIONS: After 7 days, coronal leakage decreased the concentration of hydrogen ions and calcium ion release provided by all calcium hydroxide pastes.
Hettinger, T; Strader, J; Bickerton, S J; Beers, T C
2015-01-01
Stellar multiplicity lies at the heart of many problems in modern astrophysics, including the physics of star formation, the observational properties of unresolved stellar populations, and the rates of interacting binaries such as cataclysmic variables, X-ray binaries, and Type Ia supernovae. However, little is known about the stellar multiplicity of field stars in the Milky Way, in particular about the differences in the multiplicity characteristics between metal-rich disk stars and metal-poor halo stars. In this study we perform a statistical analysis of ~15,000 F-type dwarf stars in the Milky Way through time-resolved spectroscopy with the sub-exposures archived in the Sloan Digital Sky Survey. We obtain absolute radial velocity measurements through template cross-correlation of individual sub-exposures with temporal baselines varying from minutes to years. These sparsely sampled radial velocity curves are analyzed using Markov chain Monte Carlo techniques to constrain the very short-period binary fraction...
2010-04-01
... 26 Internal Revenue 18 2010-04-01 2010-04-01 false Suspension of running of period of limitation... ADMINISTRATION Limitations Limitations on Assessment and Collection § 301.6503(d)-1 Suspension of running of... payment of any estate tax, the running of the period of limitations for collection of such tax...
On solving periodic Riccati equations
Varga, Andreas
2008-01-01
Numerically reliable algorithms to compute the periodic non-negative definite stabilizing solutions of the periodic differential Riccati equation (PRDE) and discrete-time periodic Riccati equation (DPRE) are proposed. For the numerical solution of PRDEs, a new multiple shooting-type algorithm is developed to compute the periodic solutions in an arbitrary number of time moments within one period by employing suitable discretizations of the continuous-time problems. In contrast to single shooti...
Zhang Long [College of Mathematics and System Sciences, Xinjiang University, Urumqi 830046 (China)], E-mail: longzhang_xj@sohu.com; Teng Zhidong [College of Mathematics and System Sciences, Xinjiang University, Urumqi 830046 (China)], E-mail: zhidong@xju.edu.cn
2008-05-15
In this paper, we study two species predator-prey Lotka-Volterra type dispersal system with periodic coefficients, in which the prey species can disperse among n patches, while the density-independent predator species is confined to one of the patches and cannot disperse. Sufficient conditions on the boundedness, permanence and existence of positive periodic solution for this system are established. The theoretical results are confirmed by a special example and numerical simulations.
Disadvantages of molten salt electrolysis are its low space-time-yield (kg/m3 h) combined with its high specific energy consumption (kWh/kg). These factors essentially determine how electrolysis is applied on an industrial scale. The electrolysis of tantalum was selected as an example representative for other electrolytic processes; this series of tests allow statements also on the winning of the other elements from subgroups 4 and 5 of the periodic table, and on electrolytic aluminium extraction. Optimal operating conditions for direct current electrolysis were determined in the laboratory by varying the current density and the electrolysis temperature. In order to improve the space-time-yield from an existing electrolytic cell with a given electrolyte composition beyond the optimal range of direct current electrolysis, the process of periodic current reversal is applied. In this process, the polarity is reversed for a short time at constant periodic intervals. If the forward time period and the backward time period are chosen in a suitable way, both the current efficiency and the space-time-yield can be improved without increasing the energy consumption. 59 refs., 48 figs., 8 tabs. (Author)
Maico Roris Severino
2010-12-01
Full Text Available O objetivo do presente trabalho é apresentar uma proposta para a utilização do sistema PBC (Period Batch Control, assim como de dois pré-requisitos, a saber: mudança na pol��tica de controle da qualidade e criação de uma célula virtual, para reduzir o lead time em uma empresa de bens de capital. O método de pesquisa utilizado é o estudo de caso. Resultados previstos de tal implantação indicam que a empresa estudada poderá obter vantagens significativas com a adoção do PBC como, por exemplo, redução de 46,42% no lead time do produto estudado, diminuição de custos de WIP (Work In Process em aproximadamente 50% e redução de 31% no tempo improdutivo. Esses resultados promissores podem ser alcançados também por empresas com características semelhantes que sigam a proposta apresentada neste artigo. Academicamente, o presente trabalho contribui para aumentar a divulgação do sistema PBC, assunto carente de pesquisas no Brasil.The goal of this work is to present a proposal for the use of the PBC (Period Batch Control, as well as two prerequisites, namely, to change the policy of quality control and creation of a virtual cell, to reduce the lead time in a company which produces capital goods. Case study research is the methodology used in this paper. Expected results of this implementation indicate that the company can obtain significant benefits by the adoption of PBC, such as 46.42% lead time reduction, reduction on WIP (Work In Process costs in approximately 51.56% and unproductive time in 31%. These promising results can be achieved by companies with similar characteristics. Academically, this work contribute to increase the dissemination of the PBC, a subject in need of research in Brazil.
The lead time for executing the Adjustable Fixed-Commitment (AFC) contract and exceptions which may be considered are discussed. The initial delivery period is also discussed. Delays, deferrals, and schedule adjustment charges are finally considered
Henderson, Calen B
2011-01-01
We have conducted a long-term, wide-field, high-cadence photometric monitoring survey of ~50,000 stars in the Lagoon Nebula \\ion{H}{2} region. This first paper presents rotation periods for 290 low-mass stars in NGC 6530, the young cluster illuminating the nebula, and for which we assemble a catalog of infrared and spectroscopic disk indicators, estimated masses and ages, and X-ray luminosities. The distribution of rotation periods we measure is broadly uniform for 0.5 < P < 10 d; the short-period cutoff corresponds to breakup. We observe no obvious bimodality in the period distribution, but we do find that stars with disk signatures rotate more slowly on average. The stars' X-ray luminosities are roughly flat with rotation period, at the saturation level ($\\log L_X / L_{\\rm bol} \\approx -3.3$). However, we find a significant positive correlation between $L_X / L_{\\rm bol}$ and co-rotation radius, suggesting that the observed X-ray luminosities are regulated by centrifugal stripping of the stellar coron...
Franceli da Silva; Ricardo Henrique Silva Santos; Nélio José de Andrade; Luiz Cláudio de Almeida Barbosa; Vicente Wagner Dias Casali; Renato Ribeiro de Lima; Ricardo Vaz de Melo Passarinho
2005-01-01
Fresh basil (Ocimum basilicum L.) is used in food, phytotherapic industry, and in traditional therapeutic, due to its essential oil content and composition. Nevertheless basil can not be kept for long periods after harvest and its quality can be reduced. This work aimed to assess the influence of the season and harvest time in the postharvest conservation of basil stored for different periods. Basil was harvested at 8 am and 4 pm both in August/1999 and January/2000. Cuttings were conditioned...
Insel, Aysu; Soytaş, Mehmet Ali; Gündüz, Seda
2004-01-01
The purpose of this paper is the determination of sources and pattern of business cycle in Turkey throughout the period 1988-2002 using quarterly data. The question of the paper is Has financial liberalization increased the fragility of the financial and real sides of the Turkish economy? The quantitative analysis of the paper includes the cross correlation and causality analysis. Financial development indicators are the bank credits and capital flows, efficiency indicators are the domestic...
Mohammad Amirkhan
2015-09-01
Full Text Available The supply chain network design has attracted the attention of many researchers during recent years. This paper presents a new bi-objective mixed-integer linear programming (MILP model to integrate procurement, production and distribution planning under uncertainty. This model is set up for the network of a multi-echelon, multi-product, multi-channel, multi-period supply chain with regard to two conflicting objectives, which minimize the costs and minimize the sum of backorders and surpluses of products in all periods using “activity-based costing and the total cost of ownership” and “JIT” concepts, respectively. To solve the presented model, an interactive fuzzy approach is used. The associated results show the amount of purchasing of each supplier, the quantity of producing, the inventory of raw materials and products, backorder or surplus delivery of goods, the mode of transportation, the amount of goods transported between facilities and suppliers used in each period. In addition, a numerical example is presented to demonstrate the applicability of the presented model and exhibit the efficiency of the proposed interactive fuzzy approach. Finally, the results and conclusion are provided.
Oxenløwe, Leif Katsuo; Slavik, R.; Galili, Michael;
2008-01-01
We report on the use of a novel all-fiber flat-top pulse shaping technique for improving performance and timing jitter tolerance of a switch made for 640–10 Gb/s signal demultiplexing. The jitter tolerance is increased to almost 30% of the one-bit time window, and an increase of the receiver sens...
LI W.K.; LI GuoDong
2009-01-01
@@ The authors are to be congratulated for an innovative paper in terms of both modelling methodology and subject matter significance. The analysis of short time series is known to be difficult even for linear models.
M. G. Kiselev
2015-04-01
Full Text Available The procedure for parameters definition of sawing preparations two-dimensional circulating movement, including the form of a trajectory and a direction of circulating movement is submitted. The procedure and hardware description for time measurement of the cutting tool and processable preparation contact interaction in conditions of its periodic circulating movement is given.
杨思林; 刘宁; 李纯
2011-01-01
[Objective ] The research aimed to provide experiences for successful breeding of Bengal Tiger. [ Method ] The time distribution of behaviors of No. 4 female Bengal tiger in reproductive period at Yunnan Wildlife Zoo was studied from December of 2005 to August of 2006 by using instantaneous scanning sampling method and all - occurrence recording method. [ Result]The daylight time distribution of behaviors of Bengal female tiger at different stages of reproductive period had obvious differences. Bengal female tiger during the mating season spent more time in resting, walking and other behaviors than that in gestation period. And Bengal female tiger during the mating season spent less time in sleeping than that in gestation period. The female tiger in the lactation period spent the most time in the suckling,more time in walking and resting, and less time in sleeping, eating, other behaviors (drinking, eliminating, grooming, sniffing, standing,etc. ). [Conclusion] AD kinds of behaviors of Bengal tiger changed at different stages of reproductive period. And the changes of behavior was related with the specific physiological mechanism of female tiger in the reproductive period.%[目的]为成功饲养孟加拉虎积累经验.[方法]2005年12月至2006年8月,采用瞬时扫描取样法和全事件取样法,对云南省野生动物园内繁殖期4号雌虎行为的时间分配进行了研究.[结果]繁殖期不同阶段雌虎白昼行为时间分配存在明显差异.发情交配期孟加拉虎的卧息、走动和其他行为多于妊娠期,发情交配期孟加拉虎的睡眠少于妊娠期；哺乳期母虎哺乳所占时间最多,其次是走动和卧息,而睡眠、摄食及其他行为(包括饮水、排尿、排粪、修饰、嗅闻、站立等)最少.[结论]繁殖期不同阶段孟加拉虎的各种行为均有所变化,而行为的变化与雌虎在繁殖期各阶段的特殊生理有关.
Bosch, Nienke M.; Riese, Harriette; Reijneveld, Sijmen A.; Bakker, Martin P.; Verhulst, Frank C.; Ormel, Johan; Oldehinkel, Albertine J.
2012-01-01
Objective: Altered cortisol response is a vulnerability marker for a variety of stress-related diseases and psychiatric disorders. Childhood adversity has been shown to modify this response, but evidence is inconsistent. Effects may differ depending on the timing of exposure, or due to the interplay
Bližňák, Vojtěch; Valente, M. A.; Bethke, J.
2015-01-01
Roč. 35, č. 9 (2015), s. 2400-2418. ISSN 0899-8418 Institutional support: RVO:68378289 Keywords : homogenization methods * time series * abrupt breaks * metadata * Portugal * Portuguese ex-colonies Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.157, year: 2014 http://onlinelibrary.wiley.com/doi/10.1002/joc.4151/abstract
Periodic Chandrasekhar recursions
Aknouche, Abdelhakim; Hamdi, Fayçal
2007-01-01
This paper extends the Chandrasekhar-type recursions due to Morf, Sidhu, and Kailath "Some new algorithms for recursive estimation in constant, linear, discrete-time systems, IEEE Trans. Autom. Control 19 (1974) 315-323" to the case of periodic time-varying state-space models. We show that the S-lagged increments of the one-step prediction error covariance satisfy certain recursions from which we derive some algorithms for linear least squares estimation for periodic state-space models. The p...
戴勇; 邢铁军; 雒志学; 杜明银; 魏平义
2011-01-01
利用重合度理论中的延拓定理讨论了一个具有三个成长阶段的自食单种群时滞模型正周期解的存在性,得到了保证周期解存在的充分条件.%By using a continuation theorem based on Ganies and Mawhin's coincidence degree, the authors study the global existence of positive periodic solution for a single species model with three life stage structure, cannibalism and time delay. Also, the sufficient conditions of the positive periodic solution are obtained.
Roy, P.; Quiroz-Jiménez, D.; Charles-Polo, M.; Lozano-Santacruz, R.
2013-05-01
The arid northern Mexico is part of the Sonora and Chihuahua Deserts and both the deserts belong to the North American Desert system. The North American Monsoon (NAM) or Mexican Monsoon refers to the system that brings summer precipitation to arid northern Mexico and southwestern USA. It contributes ca. 70-80% of total annual precipitation along the western slopes of the Sierra Madre Occidental (northern Mexico) and ca. 40-50% of total precipitation in Arizona and New Mexico (southwest USA). High-resolution geochemical data from lacustrine deposits located between 23°N and 31°N (paleolakes La Salada, Babicora and San Felipe) provide spatio-temporal and millennial-scale paleohydrological records related to the dynamics of summer precipitation as well as westerly winter storms over the last glacial period. The inverse relationship between proxy records of runoff into lacustrine basins of northern Mexico and winter precipitation over the southwestern USA indicate that the westerly winter storms had minimal influence south of 30°N and the paleohydrological changes are mainly summer precipitation controlled. The variation in summer season precipitation between 20 and 60 cal. kyr BP was driven by long term changes in summer insolation. During an interval of lower summer insolation (i.e. >60 cal. kyr BP), the higher summer precipitation could be related to the NAM expansion as a result of reduced north hemisphere ice sheets. On a millennial-scale, the region received more than average precipitation during the warm interstadials and vice versa.
The results of this comparative experimental study demonstrate that is possible to use the time domain reflectometry (TDR) probe as alternative to the neutron probe for soil-moisture determination. The precision of soil-moisture measurements performed with the device TRIME-tube is sufficient to evaluate the hydrological balance, while the method TDR-SSI (TDR-Signal Spatial Inversion) is promising by its simplicity and good resolution. Some limitations of these two methods are also discussed in the report
The main objective of the paper is to examine on the Rivne NPP spent fuel pools using the thermal-hydraulic MELCOR code.A series of calculations with decay heats of spent fuel in case of plant blackout was performed. The departure from nucleate boiling for the spent fuel pools was calculated, which will allow plant personnel to take specific measures on accident management taking into account the available time
Fischer, Tomáš; Horálek, Josef
2003-01-01
Roč. 35, 1/2 (2003), s. 125-144. ISSN 0264-3707 R&D Projects: GA AV ČR KSK3012103; GA ČR GA205/02/0381 Institutional research plan: CEZ:AV0Z3012916 Keywords : earthquake swarms * North-West Bohemia * space -time distribution Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.754, year: 2003
Doug Waggle; Gisung Moon
2006-01-01
Purpose –Aims to test to determine whether the selection of the historical return time interval (monthly, quarterly, semiannual, or annual) used for calculating real estate investment trust (REIT) returns has a significant effect on optimal portfolio allocations Design/methodology/approach - Using a mean-variance utility function, optimal allocations to portfolios of stocks, bonds, bills, and REITs across different levels of assumed investor risk aversion are calculated. The average historica...
M. Ceroni; M. Achkar; I. Gazzano; J. Burgeño
2015-01-01
Vegetation indices are a relevant source of information for spatial monitoring of vegetation at multiple scales. Among them, the Normalized Difference Vegetation Index (NDVI) is one of the most commonly used. This study aims to describe and analyze the spatial patterns of the NDVI in terrestrial systems in Uruguay at the onset of the 21st Century. A multiscalar approach (country, basin and sites) was applied using time series analysis of NDVI values obtained from SPOT 4 and 5 images through t...
The IAEA Safety Guide 50-SG-S8 devoted to 'Safety Aspects of Foundations of Nuclear Power Plants' indicates that operator of a NPP should establish a program for inspection of safe operation during construction, start-up and service life of the plant for obtaining data needed for estimating the life time of structures and components. At the same time the program should ensure that the safety margins are appropriate. Periodic safety analysis are an important part of the safety inspection program. Periodic safety reports is a method for testing the whole system or a part of the safety system following the precise criteria. Periodic safety analyses are not meant for qualification of the plant components. Separate analyses are devoted to: start-up, qualification of components and materials, and aging. All these analyses are described in this presentation. The last chapter describes the experience obtained for PWR-900 and PWR-1300 units from 1986-1989
Forssell, Jaakko
2015-01-01
Combined strength and endurance training has been noted to produce significant improvements in strength and endurance performances in both men and women. However, there seems to be moderate inhibitory effect regarding strength adaptations, especially considering power production. This study was conducted to investigate the effects of a 10-week combined maximal and explosive strength and high-intensity endurance training period on neuromuscular performance and 3K time-trial in m...
Johansson, Patrik (Dept. of Clinical and Experimental Medicine, Div. of Oncology, Linkoeping Univ. (Sweden)); Fohlin, Helena (Oncologic Centre, Univ. Hospital, Linkoeping (Sweden)); Arnesson, Lars-Gunnar (Dept. of Surgery, Univ. Hospital, Linkoeping (Sweden)) (and others)
2009-05-15
Purpose. Continuous minor steps of improvement in the management of breast cancer have resulted in decreased mortality rates during the last decades. The aim of this study was to compare the clinical outcome of patients with stage I breast cancer diagnosed during two time periods that differed with respect to adjuvant systemic therapy. Material and methods. The studied population consisted of all women < 60 years of age, who were diagnosed breast cancer stage I between 1986 and 1999 in south-east Sweden, a total of 1 407 cases. The cohort was divided into two groups based on the management programmes of 1986 and 1992, hereafter referred to as Period 1 and Period 2. Before 1992 the only adjuvant systemic therapy recommended was tamoxifen for hormone receptor positive patients aged 50 years or older. During Period 2 the use of adjuvant treatment was extended to younger patients at high risk, identified by a high tumour S-phase fraction, with either hormonal or cytotoxic treatment. Results. The estimated distant recurrence-free survival rate was significantly higher during Period 2 than during Period 1 (p = 0.008). Subgroup analysis showed that the most evident reduction of distant recurrence risk was among hormone receptor-negative patients (HR = 0.58, 95% CI 0.31-1.09, p = 0.09) and among patients with a high tumour S-phase fraction (HR = 0.53, 0.30-0.93, p = 0.028). The risk reduction between the periods was still statistically significant in multivariate analysis when adjusting for different tumour characteristics and treatment modalities, indicating an influence of other factors not controlled for. One such factor may be the duration of tamoxifen treatment, which likely was more frequently five years during Period 2 than during Period 1. Conclusions. We conclude that the causes of the increase in distant recurrence free survival for women with breast cancer stage I are complex. The results support though that high-risk subgroups of stage I breast cancer patients
Purpose. Continuous minor steps of improvement in the management of breast cancer have resulted in decreased mortality rates during the last decades. The aim of this study was to compare the clinical outcome of patients with stage I breast cancer diagnosed during two time periods that differed with respect to adjuvant systemic therapy. Material and methods. The studied population consisted of all women < 60 years of age, who were diagnosed breast cancer stage I between 1986 and 1999 in south-east Sweden, a total of 1 407 cases. The cohort was divided into two groups based on the management programmes of 1986 and 1992, hereafter referred to as Period 1 and Period 2. Before 1992 the only adjuvant systemic therapy recommended was tamoxifen for hormone receptor positive patients aged 50 years or older. During Period 2 the use of adjuvant treatment was extended to younger patients at high risk, identified by a high tumour S-phase fraction, with either hormonal or cytotoxic treatment. Results. The estimated distant recurrence-free survival rate was significantly higher during Period 2 than during Period 1 (p = 0.008). Subgroup analysis showed that the most evident reduction of distant recurrence risk was among hormone receptor-negative patients (HR = 0.58, 95% CI 0.31-1.09, p = 0.09) and among patients with a high tumour S-phase fraction (HR = 0.53, 0.30-0.93, p = 0.028). The risk reduction between the periods was still statistically significant in multivariate analysis when adjusting for different tumour characteristics and treatment modalities, indicating an influence of other factors not controlled for. One such factor may be the duration of tamoxifen treatment, which likely was more frequently five years during Period 2 than during Period 1. Conclusions. We conclude that the causes of the increase in distant recurrence free survival for women with breast cancer stage I are complex. The results support though that high-risk subgroups of stage I breast cancer patients
Cells anticipate periodic events
Nakagaki, Toshiyuki
2009-03-01
We show that an amoeboid organism can anticipate the timing of periodic events. The plasmodium of the true slime mold Physarum polycephalum moves rapidly under favourable conditions, but stops moving when transferred to less-favourable conditions. Plasmodia exposed to unfavourable conditions, presented in three consecutive pulses at constant intervals, reduced their locomotive speed in response to each episode. When subsequently subjected to favourable conditions, the plasmodia spontaneously reduced their locomotive speed at the time point when the next unfavourable episode would have occurred. This implied anticipation of impending environmental change. After this behaviour had been evoked several times, the locomotion of the plasmodia returned to normal; however, the anticipatory response could subsequently be induced by a single unfavourable pulse, implying recall of the memorized periodicity. We explored the mechanisms underlying these behaviours from a dynamical systems perspective. Our results hint at the cellular origins of primitive intelligence and imply that simple dynamics might be sufficient to explain its emergence.
in the lithosphere. - Highlights: • 222Rn activity concentration monitoring in cave air; • characterisation of signal series decomposition method; • application of spectral decomposition of 222Rn activity concentration signal series; • identification and characterisation of processes responsible for temporal changes in 222Rn activity concentration; • application of methods appropriate to time series analysis
Following a recommendation by the International Union for Pure and Applied Chemistry (IUPAC), the groups of the periodic table shall be numbered from 1 to 18, instead of I to VIII as before. The recommendations has been approved of by the Committee on Nomenclature of the American Chemical Society. The new system abandons the distinction between main groups (a) and auxiliary groups (b), which in the past frequently has been the reason for misunderstandings between European and American chemists, due to different handling. The publishing house VCH Verlagsgesellschaft recently produced a new periodic table that shows the old and the new numbering system together at a glance, so that chemists will have time to get familiar with the new system. In addition the new periodic table represents an extensive data compilation arranged by elements. The front page lists the chemical properties of elements, the back page their physical properties. (orig./EF)
Nonparametric Inference for Periodic Sequences
Sun, Ying
2012-02-01
This article proposes a nonparametric method for estimating the period and values of a periodic sequence when the data are evenly spaced in time. The period is estimated by a "leave-out-one-cycle" version of cross-validation (CV) and complements the periodogram, a widely used tool for period estimation. The CV method is computationally simple and implicitly penalizes multiples of the smallest period, leading to a "virtually" consistent estimator of integer periods. This estimator is investigated both theoretically and by simulation.We also propose a nonparametric test of the null hypothesis that the data have constantmean against the alternative that the sequence of means is periodic. Finally, our methodology is demonstrated on three well-known time series: the sunspots and lynx trapping data, and the El Niño series of sea surface temperatures. © 2012 American Statistical Association and the American Society for Quality.
汪东树; 王全义
2012-01-01
考虑一类具时滞和脉冲的两种群周期浮游生物植化相克系统,利用一些分析技巧和重合度理论,并巧妙构造一个同伦变换,得到该系统存在周期正解新结果,推广并改进了相关结果.%In this paper, two-species nonautonomous impulsive systems that arise in plankton allelopathy with time delays and periodic environmental factors are considered. By means of coincidence degree theory and some analysis techniques, we obtain some new results on the existence of positive periodic solutions to the system. Our results generalize and improve the related results.
A Periodic Lotka-Volterra System
Tsvetkov, D.
1996-01-01
In this paper periodic time-dependent Lotka-Volterra systems are considered. It is shown that such a system has positive periodic solutions. It is done without constructive conditions over the period and the parameters.
一类具时滞的中立型Lotka-Volterra模型的周期解%PERIODIC SOLUTION FOR A NEUTRAL LOTKA-VOLTERRA MODEL WITH TIME DELAY
李必文; 程舰
2004-01-01
n species neutral Lotka-Volterra model with time delay is discussed. By using a new continuation theorem of coincidence degree theory, a sufficient condition is obtained for the existence of a positive periodic solution of this system.%讨论了n种群时滞的中立型Lotka-Volterra生态模型.利用新的重合度理论中连续性定理,得到了该模型正周期解存在性的充分条件.
温明霞; 石孝均
2013-01-01
探讨钙对柑橘果实贮藏品质及衰老的影响，为合理调控柑橘钙素营养、延长果实的贮藏保鲜期提供理论和技术支撑.通过在北碚447锦橙(Citrus sinensis Osbeck cv. Jincheng)生长的不同时期进行树体补钙，研究钙对果实贮藏品质及酶活性的影响.结果表明，在锦橙的生长期喷钙能提高果实钙含量，抑制果实贮藏过程中维生素C 等物质的氧化分解，提高果实可溶性固形物含量和糖酸比，改善果实品质.不同时期喷钙均能提高果实中抗氧化酶(CAT、SOD)活性，降低细胞壁水解酶(PG、CX)、过氧化物酶(POD)活性，减轻脂质过氧化程度，果胶的分解转化速度减慢，丙二醛、可溶性果胶的含量明显降低，从而维持果皮具有一定的强度，延缓了果实的衰老，降低烂果的发生率，延长了果实的贮藏保鲜期.其中以幼果期喷钙在提高果实钙含量、延长贮藏期等方面的效果较好，其次是果实膨大期喷钙，成熟期喷钙效果最差.在幼果期和果实膨大期喷钙是提高果实品质、延长采后果实贮藏保鲜期的重要措施.%Calcium (Ca), as an important nutrition, can regulate the physiological metabolic process and is closely related to fruit quality, the shelf life of fruit and physiological diseases during storage time. It is meaningful to study the relation of Ca nutrition and fruit quality and senescence for producing fruit with high quality, alleviating economic loss from rotten fruit and prolonging the fruit storage time. At present, there were some reports about Ca nutrition and fruit quality but many reported the effect of Ca on storage property of fruit by studying the respiration intensity and electric conductivity of fruits supplementing Ca solution on fruit during maturing stage or harvest time, few reported the effect of Ca on the inherent quality and the shelf life of fruits supplying Ca nutrition during fruit growing period. In
Vicente Navarro, Eduardo
2006-01-01
The present essay is designed to be a general introduction to the philosophical problem of time from its very different forms and ways of approaching. In this sense, the article covers the problem from different perspectives and gives a brief account of the plurality and diversity of the time found in the different philosophical definitions, in the different layers of knowledge, in different periods and cultures and also in the different instruments used to measure time itself
卢小琴; 田秀华
2011-01-01
The instantaneous scan method was used to study the time budget of breeding behaviors and activity rhythm of Great Bustards in Changchun Zoological and Botanical Gardens during April-August in 2010. The differences in time budget of behaviors of Great Bustards in the same breeding period between male and female and of the same sex between different breeding periods were analyzed by independent sample T-test. Results show that the time budget of behaviors and activity rhythm of the Great bustards are regular to some degree. Feeding mostly occurs in the middle of the morning and the afternoon, flaunting and hatching mostly in the morning and evening, and resting mostly occurs at noon. During the prophase of breeding, the Great bustards spend their time mainly in standing, lying and walking, and the male and the female spend 80.63％ and 66.34％ of their time on the three behaviors, respectively. The time budget of the male changes greatly during the anaphase of breeding. They spend 90.41％ of their time in incubating in the nest, and incubating, feeding and alerting behaviors have an obvious rhythm; however, the male still spend 59.23％ of their time mainly in standing, lying and walking. The time budget of behaviors of Great Bustards exhibits differences not only between the male and the female, but also between the prophase and anaphase of breeding.%2010年4月到8月,采用瞬时扫描法对长春动植物公园两对繁殖良好的大鸨的繁殖行为时间分配和活动节律进行了研究,并利用独立样本T检验分析了不同性别大鸨繁殖前后期行为的性别差异,以及相同性别的大鸨在繁殖的不同时期的行为差异.结果表示:大鸨繁殖期的各种行为活动具有一定的时间分配和日节律,取食行为多发生在上午和下午的中间时段,炫耀、孵化多在早晨和傍晚,而中午的大部分时间处于休息状态.繁殖前期,大鸨的行为主要表现为静立、趴卧和游走,雌雄大鸨的这3
Sergio Luiz Colucci de Carvalho
2005-12-01
Full Text Available Na produção do abacaxi, é importante conhecer o efeito do clima no ciclo da cultura. O objetivo do trabalho foi estudar as somas térmicas do período da indução floral à colheita de abacaxi 'Smooth Cayenne' para diferentes épocas de indução floral no Norte do Paraná e sua influência na produção e qualidade dos frutos. Os tratamentos foram indução floral artificial com ethephon, nos meses de abril, maio, junho e julho, além da testemunha, induzida naturalmente. A inflorescência surgiu aos 115,5; 107,3; 77,3 e 48,3 dias após a indução floral, respectivamente, para os tratamentos de abril, maio, junho e julho. O período entre o surgimento da inflorescência e a colheita foi de 163 dias para a indução de abril, maior do que o observado para os demais tratamentos (144 a 151 dias. O tratamento de abril proporcionou frutos menores do que o de julho, mas a acidez titulável, o teor de sólidos solúveis e o "ratio" não foram influenciados pelas épocas de aplicação do indutor. A soma térmica média do período entre o florescimento e a colheita foi de 1.090 graus-dia, sem diferenças estatísticas entre as épocas de indução floral.The knowledge of climate effects is important in planning pineapple production. The aim of this research was to accomplish the thermal time requirements of 'Smooth Cayenne' pineapple from the floral induction to the harvest period for different periods of artificial floral induction at Northern State of Paraná and also its influence in yield and fruit quality. The treatments were floral induction with ethephon in April, May, June and July. The control had natural induction. The inflorescence arose at 115.5; 107.3; 77.3 and 48.3 days after the floral induction for the applications in April, May, June, and July, respectively. The period between inflorescence arisen and harvest was 163 days for April induction, which was higher than for the other treatments (144 - 151 days. The fruits from the
... Management Education & Events Advocacy For Patients About ACOG Dysmenorrhea: Painful Periods Home For Patients Search FAQs Dysmenorrhea: ... Dysmenorrhea: Painful Periods FAQ046, January 2015 PDF Format Dysmenorrhea: Painful Periods Gynecologic Problems What is dysmenorrhea? How ...
... two most common types of periodic paralyses are: Hypokalemic periodic paralysis is characterized by a fall in potassium levels ... chronic muscle weakness later in life. Hyperkalemic periodic paralysis is ... than the hypokalemic form. Muscle spasms are common. Is there any ...
A highly specific test for periodicity
We present a method that allows to distinguish between nearly periodic and strictly periodic time series. To this purpose, we employ a conservative criterion for periodicity, namely, that the time series can be interpolated by a periodic function whose local extrema are also present in the time series. Our method is intended for the analysis of time series generated by deterministic time-continuous dynamical systems, where it can help telling periodic dynamics from chaotic or transient ones. We empirically investigate our method's performance and compare it to an approach based on marker events (or Poincaré sections). We demonstrate that our method is capable of detecting small deviations from periodicity and outperforms the marker-event-based approach in typical situations. Our method requires no adjustment of parameters to the individual time series, yields the period length with a precision that exceeds the sampling rate, and its runtime grows asymptotically linear with the length of the time series
A highly specific test for periodicity
Ansmann, Gerrit, E-mail: gansmann@uni-bonn.de [Department of Epileptology, University of Bonn, Sigmund-Freud-Straße 25, 53105 Bonn (Germany); Helmholtz Institute for Radiation and Nuclear Physics, University of Bonn, Nussallee 14–16, 53115 Bonn (Germany); Interdisciplinary Center for Complex Systems, University of Bonn, Brühler Straße 7, 53175 Bonn (Germany)
2015-11-15
We present a method that allows to distinguish between nearly periodic and strictly periodic time series. To this purpose, we employ a conservative criterion for periodicity, namely, that the time series can be interpolated by a periodic function whose local extrema are also present in the time series. Our method is intended for the analysis of time series generated by deterministic time-continuous dynamical systems, where it can help telling periodic dynamics from chaotic or transient ones. We empirically investigate our method's performance and compare it to an approach based on marker events (or Poincaré sections). We demonstrate that our method is capable of detecting small deviations from periodicity and outperforms the marker-event-based approach in typical situations. Our method requires no adjustment of parameters to the individual time series, yields the period length with a precision that exceeds the sampling rate, and its runtime grows asymptotically linear with the length of the time series.
Algebraically periodic translation surfaces
Calta, Kariane; Smillie, John
2007-01-01
Algebraically periodic directions on translation surfaces were introduced by Calta in her study of genus two translation surfaces. We say that a translation surface with three or more algebraically periodic directions is an algebraically periodic surface. We show that for an algebraically periodic surface the slopes of the algebraically periodic directions are given by a number field which we call the periodic direction field. We show that translation surfaces with pseudo-Anosov automorphisms...
2010-10-01
... 46 Shipping 1 2010-10-01 2010-10-01 false Broken periods. 9.8 Section 9.8 Shipping COAST GUARD... § 9.8 Broken periods. In computing extra compensation where the services rendered are in broken periods and less than 2 hours intervene between such broken periods the time served should be...
蔡路昀; 马帅; 程煊茹; 曹爱玲; 冯建慧; 励建荣
2016-01-01
In order to discuss the effects of different roasting time periods on character and flavor in sardine slices,the color,texture and the variations of volatile components in sardine slices at different roasting time periods were measured.The volatile aroma compounds in sardine slices at different roasting time periods were analyzed by electronic nose and headspace solid-phase microextraction was coupled with gas chromatography-mass spectrometry (GC-MS).The results revealed that with the increase of roasting,hardness,chewiness of sardine slices significantly increased,while springiness decreased during roasting.Electronic nose could discriminate the flavor characteristics of sardine slices at different roasting.Principal component analyses (PCA) showed that the apparent differences among samples roasted with different time periods could be well discriminated by electronic nose.The analyses of GC-MS showed that the volatile components of sardine slices at different roasting time changed obviously,the main volatile substances were alcohol,ester,aldehyde,ketone,acid,hydrocarbon,aromatic,nitrogen compounds,etc.With the increase of roasting time,43,47,47,54,46 kinds of volatile compounds were detected respectively,and the content of acids,esters,hydrocarbons,aromatic showed a trend of decline after an initial rising,while the content of alcohols,aldehydes,ketones showed a trend of rising after an initial decline.At the same time,pyrazine,pyrrole,thiazole and other aroma compounds were produced,which made a significant contribution to aroma of roasted sardine slices.%为探讨烤制时间对沙丁鱼片风味及品质的影响,以沙丁鱼为研究对象,研究经不同烤制时间处理的沙丁鱼片的色泽、质构特性及挥发性成分的变化.采用电子鼻和顶空固相微萃取—气质联用技术分析沙丁鱼片在不同烤制时间过程中挥发性成分的变化.结果表明,随着烤制时间的延长,沙丁鱼肉的硬度、咀嚼度均有提高,弹
The Bulgarian-Russian dosimeter-radiometer LIULIN was installed in the working compartment of the MIR space station. The effective mass thickness of screening matter inside the working compartment of MIR is evaluated to be 6-15 g/cm2. The main contribution to the dose rate is given by protons and electrons outside MIR space station the have energy larger than 100 MeV and 10 MeV respectively. LIULIN measurements were carried out under a wide variety of solar and geomagnetic activity conditions. They provide an excellent opportunity to study effects on the dose-rates and fluxes in the near Earth radiation environment over long time periods, as well as rapid change, induced by solar proton events and geomagnetic disturbances. This paper presents an overview of all major experimental results obtained by the LIULIN instrument for galactic cosmic rays, Earth radiation belts and solar proton events in the 1989-1994 time interval. The Mobile Radiation Exposure Control Subsystem (LIULIN-4) is a part of the Space Radiation Control System, which is developed to be placed at large Russian inhabited ISS objects with a long living time. The LIULIN-4 main purpose is to monitor simultaneously the doses and fluxes at four independent places of the segment. In the case of special study the subsystem can be used for personal monitoring of the doses and fluxes obtained in seven days by four selected cosmonauts. LIULIN-4 has been developed in cooperation with Russian, German, American and Belgian scientists. Airplane flight results and proton calibrations are obtained and presented by the LIULIN-3M instrument. The LIULIN-3M instrument was a precursor of LIULIN-4. (author)
于娜; 于继来; 王承民
2009-01-01
结合初期电力市场特点,从高峰期有功调度出发,提出了一种综合考虑电源侧、电网侧和需求侧多个约束的可中断负荷的优化调度模型.模型除侧重考虑网络阻断容量约束外,还考虑了可中断负荷提前通知时间、中断负荷持续时间、中断负荷位置对网损的影响.采用离散二进制粒子群优化(BPSO)与内点法相结合的方法求解优化问题.算例结果表明,该模型能够适应电力市场初期可中断负荷参与电网高峰期网络受阻约束调度的需要.%Interruptible load management (ILM) is one of the demand response incentives. It is good to the reliability of the power system. During the peak time of the power system, there are always congestion restrictions. Based on the active power dispatch, an optimal IL purchasing model including hybrid generation, network and demand side restrictions was presented. This model not only puts emphasis on the network congestion capacity restriction but considers the influence of pre-informed time and the interruption duration period and the geographical position on network loss. The binary version of the particle swarm optimization (BPSO) method was used to solve this model. The simulation result shows that the model is fit for using IL in peak load congestion restricted dispatch in developing power market.
Lara-Castells, María Pilar de, E-mail: Pilar.deLara.Castells@csic.es [Instituto de Física Fundamental (C.S.I.C.), Serrano 123, E-28006 Madrid (Spain); Stoll, Hermann [Institut für Theoretische Chemie, Universität Stuttgart, D-70550 Stuttgart (Germany); Civalleri, Bartolomeo [Dipartimento di Chimica e Centro Interdipartimentale NIS, Universitá di Torino, Via P. Giuria 7, 10125 Torino (Italy); Causà, Mauro [Dipartimento di Ingegneria Chimica, dei Materiali e delle Produzioni Industriali, Universiá di Napoli Federico II, Piazzale Tecchio, 80126 Napoli (Italy); Voloshina, Elena [Humboldt-Universität zu Berlin, Institut für Chemie, Brook-Taylor-Str. 2, 12489 Berlin (Germany); Mitrushchenkov, Alexander O. [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France); Pi, Martí [Department ECM, Facultat de Física, and IN" 2UB, Universitat de Barcelona, Diagonal 645, E-08028 Barcelona (Spain)
2014-10-21
In this work we propose a general strategy to calculate accurate He–surface interaction potentials. It extends the dispersionless density functional approach recently developed by Pernal et al. [Phys. Rev. Lett. 103, 263201 (2009)] to adsorbate-surface interactions by including periodic boundary conditions. We also introduce a scheme to parametrize the dispersion interaction by calculating two- and three-body dispersion terms at coupled cluster singles and doubles and perturbative triples (CCSD(T)) level via the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)]. The performance of the composite approach is tested on {sup 4}He/graphene by determining the energies of the low-lying selective adsorption states, finding an excellent agreement with the best available theoretical data. Second, the capability of the approach to describe dispersionless correlation effects realistically is used to extract dispersion effects in time-dependent density functional simulations on the collision of {sup 4}He droplets with a single graphene sheet. It is found that dispersion effects play a key role in the fast spreading of the {sup 4}He nanodroplet, the evaporation-like process of helium atoms, and the formation of solid-like helium structures. These characteristics are expected to be quite general and highly relevant to explain experimental measurements with the newly developed helium droplet mediated deposition technique.
In this work we propose a general strategy to calculate accurate He–surface interaction potentials. It extends the dispersionless density functional approach recently developed by Pernal et al. [Phys. Rev. Lett. 103, 263201 (2009)] to adsorbate-surface interactions by including periodic boundary conditions. We also introduce a scheme to parametrize the dispersion interaction by calculating two- and three-body dispersion terms at coupled cluster singles and doubles and perturbative triples (CCSD(T)) level via the method of increments [H. Stoll, J. Chem. Phys. 97, 8449 (1992)]. The performance of the composite approach is tested on 4He/graphene by determining the energies of the low-lying selective adsorption states, finding an excellent agreement with the best available theoretical data. Second, the capability of the approach to describe dispersionless correlation effects realistically is used to extract dispersion effects in time-dependent density functional simulations on the collision of 4He droplets with a single graphene sheet. It is found that dispersion effects play a key role in the fast spreading of the 4He nanodroplet, the evaporation-like process of helium atoms, and the formation of solid-like helium structures. These characteristics are expected to be quite general and highly relevant to explain experimental measurements with the newly developed helium droplet mediated deposition technique
Fábio Roberto Cabar
2008-06-01
incidence of placental abruption (PA, fetal death and the profile of maternal factors associated with fetal death in pregnancies affected by placental abruption during two different time periods in the same hospital. METHODS: retrospective study between January 1, 1994 and December 31, 1997 and April 1, 2001 and March 31, 2005, including singleton pregnancies with a birth weight higher than 500g and gestational age of more than 20 weeks. Factors analyzed were maternal age, race, obstetric history, presence of arterial hypertension or premature rupture of membranes, presence of genital bleeding, presence of amniotic fluid contaminated with blood, characteristics of uterine tonus, occurrence of renal insufficiency, postpartum coagulopathy, puerperal anemia, gestational age and weight at birth. RESULTS: there were7692 births in the 1994-1997 period, placental abruption incidence of 0.78% (60 cases; 8644 births occurred in the 2001-2005 period, placental abruption incidence of 0.59% (51 cases, with no statistical difference. During the 1994-1997 period, proportion of cases without genital bleeding was significantly higher in the group whose fetuses died compared to cases of live born fetuses (57.9% vs 22.0%; p=0.01. During the 2001-2005 period, proportion of cases with uterine hypertonia was significantly higher in the group whose fetuses died compared to cases of live born fetuses (66.7% vs 29.3%; p=0.04. Postpartum maternal complications were more frequent in cases of fetal death during both periods (31.6% vs 4.9%; p=0.009; and 50% vs 5.1%; p=0.001, respectively. CONCLUSION: Placental abruption continues to be a serious obstetric problem, with fatal consequences, especially when the placental abruption area is large. Maternal clinical symptoms are more severe in cases of fetal death.
段飞腾; 崔宝同
2016-01-01
Memristor is a nonlinear two-terminal passive electronic component,which is proposed in recent years and is different from the resistor,capacitor and inductor.The memristor-based recurrent neural networks,with different system parameters,show all kinds of dynamic performances.We investigated global exponential periodicity problem in regard to a class of memristor-based recurrent neural networks with time-varying delays,and considered the symmetry and asymmetry situations of connection weights in switching state.Via the studying approach of constructing two proper Lyapunov functions,the Halanay inequality and the theory of differential equations with discontinuous right-hand sides introduced by Fillippov,we presented the sufficiency condition concerning the global exponential periodicity.Finally, experimental results verified the feasibility and effectiveness of the proposed theory.%忆阻器是近几年来提出的一种区别于电阻、电容、电感的一类非线性两端无源电子元件，而忆阻器递归神经网络由于系统参数的不同，系统表现出各种动态性能。针对一类变时滞忆阻器递归神经网络，研究全局指数周期性问题，考虑连接权值在切换状态下的对称和非对称的情况，通过构造两个 Lyapunov 函数、Halanay 不等式和由 Fillippov 给出的右端不连续微分方程理论的研究方法，提出关于全局指数周期性的充分性条件。最后，实验结果验证了所提理论的可行性和有效性。
João Carlos Felício
1991-01-01
Full Text Available Avaliaram-se os resultados de rendimento dos cultivares de trigo CNT-8, IAC-17 e BH-1146 em oito épocas de semeadura (a primeira no primeiro decêndio de março e a última no terceiro decêndio de maio, na Fazenda Canadá, em Assis (SP, durante o qüinqüênio 1978/82. Em cada época de semeadura, efetuaram-se avaliações de rendimento de grãos e altura de plantas. A disponibilidade hídrica do solo para a cultura foi caracterizada através de balanço hídrico decendial, considerando 125mm como a capacidade máxima de retenção de água no solo. Os resultados indicaram como a melhor faixa de semeadura, independente de cultivar, o período compreendido entre o terceiro decêndio de março e o primeiro decêndio de abril. Indicaram, também, que os períodos extremos estudados são pouco favoráveis à semeadura do trigo na região. O cultivar CNT-8 foi o mais produtivo, de maior porte de planta, independente do ano e da época de semeadura. Entre os anos em estudo, destacou-se o de 1979, cujos cultivares de trigo exibiram as maiores produções de grãos, em vista das condições climáticas favoráveis para a cultura.This paper presents the behaviour of three wheat cultivara (CNT 8, IAC 17 and BH-1146 at eight seeding times (the first seeding time was from 1st to 10th of March and the last one from to 20th to 30th of May in experiments carried out at Canadá Farm, Assis, State of Sáo Paulo, Brazil, in the period 1978-1982. Grain yield and plant heigth were evaluated for each seeding time, in each experiment. Soil water availability was obtained by water balances taken at each ten days considering 125mm as the soil water retention capacity. The results showed that the seeding time from 20th of March to 10th of April was the best considering grain yield, independently of the cultivar. The results also indicated that the others studied seeding times were not favourable to seed wheat in this region. The wheat cultivar CNT 8 was the most
付俊敏; 刘宁; 楚原梦冉; 胡明宇
2014-01-01
于2012年10月至2013年9月在云南野生动物园，采用瞬时扫描法和全事件观察法对繁殖期白化孟加拉虎的行为进行了研究。结果表明：在发情交配期雌雄白化孟加拉虎的行为时间分配差异不显著（P＞0．05），均将较多的时间用于休息和运动；在妊娠期雌性白化孟加拉虎将较多的时间用于休息和运动，较少的时间用于摄食、睡眠和其它行为，对比妊娠期4只雌虎的行为，不同个体在同一种行为间差异性极显著（P＜0．01）；产仔期雌虎将更多的时间用于产仔和舔舐幼虎，其次是休息；在哺乳期雌虎将较多的时间用于休息，其次是哺乳和运动。通过单因素方差分析表明，在繁殖期不同阶段休息行为差异性极显著（P＜0．01），睡眠、运动和其它行为差异性不显著（P＞0．05）。%This study uses instantaneous scanning sampling method and all -occurrence recording method to observe the breeding behaviors of six Bengal white tigers at Yunnan Wild Animal Park from October 2012 to September 2013 . The results show that the behavior distributions of mating male and female Bengal white tigers are not significant (P>0 .05) ,all of which spend more time in rest and moving ;in gestation periods ,female Bengal white tiger spend most time in resting and moving ,less time in eating ,sleeping and other behaviors .Compared with the behaviors of four pregnant female tigers ,the study finds that different tigers have extremely remarkable differences in one behavior (P0 .05) show no significant change .
... you sexually active? Do you use birth control? What type? When was your last menstrual period? Was the flow of your last menstrual period a normal amount for you? Do your periods tend ... with menstruation? What have you done to try to relieve the ...
Hennigan, Jennifer N.; Grubbs, W. Tandy
2013-01-01
The chemical elements present in the modern periodic table are arranged in terms of atomic numbers and chemical periodicity. Periodicity arises from quantum mechanical limitations on how many electrons can occupy various shells and subshells of an atom. The shell model of the atom predicts that a maximum of 2, 8, 18, and 32 electrons can occupy…
Periodicities in Aerosol Optical Depths
Ramachandran, S; Verma, Amit; Panigrahi, Prasanta K
2011-01-01
We investigate the temporal and spatial variability in aerosol optical depth (AOD) over different geographic locations in India due to their important role in the earth-atmosphere radiation budget. The use of continuous wavelet transform pinpoints the spatio-temporal non-stationarity of the periodic variations in the AOD depending on local factors. The optimal time-frequency localization ability of Morlet wavelet accurately isolates the periodic features in the different frequency domains, to study the variations in the dominant periods due to local effects. The origin of the effects on the periodic modulations is then related to physical phenomena of regional nature, which throws considerable light on the observed variations in aerosol optical depths. We also find the phase relationship between different locations and to identify the possible correlations between different geographic locations and related environmental variations.
Model selection in periodic autoregressions
Ph.H.B.F. Franses (Philip Hans); R. Paap (Richard)
1994-01-01
textabstractThis paper focuses on the issue of period autoagressive time series models (PAR) selection in practice. One aspect of model selection is the choice for the appropriate PAR order. This can be of interest for the valuation of economic models. Further, the appropriate PAR order is important
Periodic solutions of nonlinear vibrating beams
J. Berkovits
2003-01-01
Full Text Available The aim of this paper is to prove new existence and multiplicity results for periodic semilinear beam equation with a nonlinear time-independent perturbation in case the period is not prescribed. Since the spectrum of the linear part varies with the period, the solvability of the equation depends crucially on the period which can be chosen as a free parameter. Since the period of the external forcing is generally unknown a priori, we consider the following natural problem. For a given time-independent nonlinearity, find periods T for which the equation is solvable for any T-periodic forcing. We will also deal with the existence of multiple solutions when the nonlinearity interacts with the spectrum of the linear part. We show that under certain conditions multiple solutions do exist for any small forcing term with suitable period T. The results are obtained via generalized Leray-Schauder degree and reductions to invariant subspaces.
Franceli da Silva
2005-04-01
Full Text Available Fresh basil (Ocimum basilicum L. is used in food, phytotherapic industry, and in traditional therapeutic, due to its essential oil content and composition. Nevertheless basil can not be kept for long periods after harvest and its quality can be reduced. This work aimed to assess the influence of the season and harvest time in the postharvest conservation of basil stored for different periods. Basil was harvested at 8 am and 4 pm both in August/1999 and January/2000. Cuttings were conditioned in PVC packages and stored for 3, 6, and 9 days. During storage, chlorophyll content, essential oil content and composition were determined as well as microbiological analyses were carried out. Harvest season and the days of storage influenced the final content of essential oil. There was a linear decrease in the content of essential oil, in the chlorophyll content and in the number of mold and yeast colonies during storage. There was no effect of cropping season or harvest hour on essential oil composition, but the eugenol and linalool content increased during storage. Coliforms were under 0.3 MPN g-1 and the number of Staphylococcus aureus was under 1.0x10² UFC g-1.O manjericão (Ocimum basilicum L. é empregado tanto na indústria culinária quanto fitoterápica e na medicina tradicional, devido ao teor e composição de seu óleo essencial. No entanto, o manjericão não pode ser conservado por longo período após a colheita e sua qualidade pode ser prejudicada. O objetivo deste trabalho foi verificar a influência da época e do horário de colheita sobre a conservação de manjericão armazenado por diferentes períodos. O manjericão foi colhido às 8h e às 16h em agosto/1999 e em janeiro/2000. Os ramos foram acondicionados em filmes de PVC e armazenados por 3, 6 e 9 dias. Durante o armazenamento, o teor de clorofila, e o teor e a composição do óleo essencial foram determinados e foram conduzidas análises microbiológicas. A época de colheita
Periodicity of chaotic solutions
Berezowski, Marek
2016-01-01
The scope of the paper is the analysis of the impact of flow reversal on the dynamics of cascades of reactors. Periodic and chaotic oscillations occur in the analyzed system. There is a dependence between the oscillation period of the state variable of the system without flow reversal and the recurrence period of windows of chaos in the steady-state diagram of the system with flow reversal.
Crystallography without periodicity
A condition of physics stability, applied to materials with sharp Bragg peaks, leads to rules for a unified approach to their classification that make no use of periodicity, applying equally well to either periodic or quasiperiodic materials. Three-dimensional geometric intuition is the primary analytical tool for extracting the classification from the rules. Recognizing that periodicity is not required to formulate crystallography removes the need for an algebraic formalization of that intuition in a higher dimensional superspace, where the material can be embedded in a periodic supercrystal. Selected examples illustrate the simplicity of the resulting description of ordinary crystals, quasicrystals, modulated crystals, intergrowth crystals, or modulated quasicrystals. (Author) 9 refs
A new pattern of the periodic table
Brajendra Nath Tripathi
1962-07-01
Full Text Available A new pattern of the Periodic Table is described which incorporates all the points for which various models of two or three dimensional tables have been proposed from time to time.
Sheila Fanan
2009-09-01
Full Text Available As atuais preocupações quanto à escassez das reservas de petróleo e o agravamento do efeito estufa, pela emissão de CO2, levam a cultura da mamona a ser uma das fontes para energia renovável. Sabe-se que ao longo do ciclo da mamona são produzidos racemos de várias ordens, que se desenvolvem sob diferentes condições ambientais, podendo provocar variações na qualidade das sementes. Assim, objetivou-se avaliar a interferência da colheita e de cinco períodos de armazenamento na qualidade sanitária das sementes de mamona, cultivar IAC-2028. Para tanto, foram instalados os testes de germinação e sanidade, logo após a colheita e aos 3; 6; 9 e 12 meses de armazenamento em condições não controladas de temperatura e umidade relativa do ar. As avaliações foram feitas em esquema de parcela subdividida no tempo, onde as parcelas foram constituídas por cinco épocas trimestrais de avaliação e as sub-parcelas por 11 tratamentos. Os resultados sugerem que todos os racemos podem ser colhidos em uma única etapa, sem que ocorram perdas de qualidade das sementes.The current concerns with the scarcity of oil reserves and the aggravation of the stove effect due to CO2 emission makes the castor bean oil one viable sources for renewable energy. During the crop growth racemes are produced in several orders that develop under different environment conditions, which can cause variations in quality of the seeds on the field and storage. The purpose of this work was to evaluate effect of harvest and five periods of storage on sanitary quality of seeds of castor bean cultivar IAC-2028. The evaluation of the quality of the seeds consisted of germination and sanitary test immediately after harvest, and at 3; 6; 9 and 12 months of storage under uncontrolled conditions of air temperature and relative humidity. The results suggest that all the racemes can be harvested in a single harvesting time, without losses quality of the castor bean seeds.
B. Koehler
2009-12-01
Full Text Available Atmospheric nitrogen (N deposition is rapidly increasing in tropical regions. We studied the response of soil carbon dioxide (CO_{2} efflux to long-term experimental N addition (125 kg N ha^{−1} yr^{−1} in mature lowland and montane forests in Panama. In the lowland forest, on soils with high nutrient-supplying and buffering capacity, fine litterfall and stem-growth were neither N- nor phosphorus-limited. In the montane forest, on soils with low nutrient supplying capacity and an organic layer, fine litterfall and stem-growth were N-limited. Our objectives were to 1 explore the influence of soil temperature and moisture on the dynamics of soil CO_{2} efflux and 2 determine the responses of soil CO_{2} efflux from an N-rich and N-limited forest to elevated N input. Annual soil CO_{2}-C efflux was larger in the lowland (15.44 ± 1.02 Mg C ha^{−1} than in the montane forest (9.37 ± 0.28 Mg C ha^{−1}. In the lowland forest, soil moisture explained the largest fraction of the variance in soil CO_{2} efflux while soil temperature was the main explanatory variable in the montane forest. Soil CO_{2} efflux in the lowland forest did not differ between the control and 9–11 yr N-addition plots, suggesting that chronic N input to nutrient-rich tropical lowland forests on well-buffered soils may not change their C balance on a decadal time scale. In the montane forest, first year N addition did not affect soil CO_{2} efflux but annual CO_{2} efflux was reduced by 14% and 8% in the 2nd and 3rd year N-addition plots, respectively, compared to the control. This reduction was caused by a decrease in soil CO_{2} efflux during the high stem-growth period of the year, suggesting a shift in carbon partitioning from below- to aboveground in the N-addition plots in which stem diameter growth was promoted.
Periodic Monopoles from Spectral Curves
Maldonado, R.
2012-01-01
We consider $\\text{SU}(2)$ Bogomolny equations on $\\mathbb{R}^2\\times\\hat{S}^1$ and use the spectral curve defined by the holonomy in the periodic direction to approximate the fields in the limit of large size to period ratio. Symmetries of the Nahm transform allow a study of the effective two dimensional dynamics, which is compared with known results on the full moduli space. The techniques are applied to systems of higher charge and higher rank gauge group, allowing a direct comparison to o...
Availability of periodically tested systems
There is at the present time a need in accurate models to asess the availability of periodically tested stand-by systems. This paper shows how to improve the well known 'saw-tooth curve' model in order to take into account various reliability parameters. A model is developed to assess the pointwise and the mean availabilities of periodically tested stand-by systems. Exact and approxination formulae are given. In addition, the model developed herein leads to optimize the test interval in order to minimize the mean unavailability. A safety diesel in a nuclear power plant is given as an example
Discovery of periodic patterns in spatiotemporal sequences
Cao, H.; Mamoulis, N; Cheung, DW
2007-01-01
In many applications that track and analyze spatiotemporal data, movements obey periodic patterns; the objects follow the same routes (approximately) over regular time intervals. For example, people wake up at the same time and follow more or less the same route to their work everyday. The discovery of hidden periodic patterns in spatiotemporal data could unveil important information to the data analyst. Existing approaches for discovering periodic patterns focus on symbol sequences. However,...
Historically defined autobiographical periods
Brown, Norman R.; Hansen, Tia G. B.; Lee, Peter J.;
2012-01-01
The chapter reviews a research programme that has demonstrated the existence of historically defined autobiographical periods and identified the conditions that bring them about. Data from four samples of World War II-generation adults show that historically defined autobiographical periods endure...
Nahlik, Mary Schrodt
2005-01-01
To help make the abstract world of chemistry more concrete eighth-grade students, the author has them create a living periodic table that can be displayed in the classroom or hallway. This display includes information about the elements arranged in the traditional periodic table format, but also includes visual real-world representations of the…
Maisondieu, Christophe; Giebhardt, Jochen; Tetu, Amelie; Johnstone, Cameron; Healy, Mark
The work described in this publication has received support from the European Community - Research Infrastructure Action under the FP7 “Capacities” Specific Programme through grant agreement number 262552, MaRINET. Project Periodic Report. 2nd Period: October 2012 – March 2014 inclusive....
Sorokin, Sergey V.
2015-01-01
. In each case, special attention is paid to eigenfrequencies and eigenmodes of a single periodicity cell with appropriate boundary conditions. The influence of the amount of periodicity cells in a finite compound structure on its eigenfrequency spectrum is analyzed. Several features common for the......The talk is concerned with the modelling of wave propagation in and vibration of periodic elastic structures. Although analysis of wave-guide properties of infinite periodic structures is a well establish research subject, some issues have not yet been fully addressed in the literature. The aim of...... the talk is to illustrate these issues in simple examples and to discuss possible applications and generalisations. First, the eigenfrequency spectra of finite periodic structures are compared with the location of stop-bands for their infinite counterparts for a hierarchy of four mathematical models...
Periodicity, the Canon and Sport
Thomas F. Scanlon
2015-10-01
Full Text Available The topic according to this title is admittedly a broad one, embracing two very general concepts of time and of the cultural valuation of artistic products. Both phenomena are, in the present view, largely constructed by their contemporary cultures, and given authority to a great extent from the prestige of the past. The antiquity of tradition brings with it a certain cachet. Even though there may be peripheral debates in any given society which question the specifics of periodization or canonicity, individuals generally accept the consensus designation of a sequence of historical periods and they accept a list of highly valued artistic works as canonical or authoritative. We will first examine some of the processes of periodization and of canon-formation, after which we will discuss some specific examples of how these processes have worked in the sport of two ancient cultures, namely Greece and Mesoamerica.
Painful periods (dysmenorrhea) (image)
Primary dysmenorrhea is a normal cramping of the lower abdomen caused by hormone-induced uterine contractions before the period. Secondary dysmenorrhea may be caused by abnormal conditions such as ...
Saturnelli, Annette
1985-01-01
Examines problems resulting from different forms of the periodic table, indicating that New York State schools use a form reflecting the International Union of Pure and Applied Chemistry's 1984 recommendations. Other formats used and reasons for standardization are discussed. (DH)
Banks, Alton J.; Holmes, Jon L.
1995-01-01
Describes the characteristics of the digitized version of The Periodic Table Videodisc. Provides details about the organization of information and access to the data via Macintosh and Windows computers. (DDR)
Social Research On Renaissance Period
张蕾蕾
2009-01-01
The historical period known as the Renaissance spans the fifteenth and siXteenth centuries. ‘Renaissance'means‘re-birth'in French and during this time Europe left behind the mindset of the Midge Ages and created the beginnings of the modern world.This thesis mainly rotates on the background,the main features and significance of Renaissance,especially focuses on the discovery of man and the humanism and the detailed unfolding of the society on several aspect in Renaissance.
Period meter output during startup transients
The time response of a period meter whose input signal comes from an ionization chamber may be calculated using a Ferranti Mercury digital computer programme. Details of the programme are given. The type of period meter considered is the one for which the input time constant is determined by the input capacity and the logarithmic element. The input excitation is a terminated ramp of reactivity. Other reactivity inputs may be treated. In particular the step change of reactivity may be used as the input excitation. Allowance is taken of the power dependent time constant associated with the logarithmic element and of the differentiating and integrating time constants in the period meter. The programme may be used by period meter designers to assess the performance of their instruments and may also be used by those carrying out safety and operations studies on reactors which use this type of period meter. An example of the use of the programme is given. (author)
高峰; 纪建伟; 田恒玖; 史洋; 潘红; 孙翔楠; 张铁楼; 胡严; 张志明
2013-01-01
2012年3～5月,采用直接瞬时扫描法和间接监控器摄像相结合的方式,对北京市野生动物救护中心顺义饲养繁育基地的一对秃鹫的繁殖行为的时间分配和活动规律进行了研究,结果显示:秃鹫在警戒、理羽、吃食、交配、孵化等行为存在着明显的节律性,警戒、理羽行为在行为比例中较高,警戒行为占绝对优势.取食行为多发生在上午的中间阶段,孵化行为不间断、并且轮流孵化幼鸟.孵化期内雌、雄个体的行为差异不大,秃鹫发情期各种行为所占的比例存在着一定的性别差异.%During the period from March to May 2012, direct instant scanning in combination with video monitoring were used to study the breeding activities of a pair of captive Cinereous Vultures during the breeding period in Shunyi breeding research base of the Beijing wildlife rescue center. The Vultures exhibited obvious behavior rhythms in warning, preparing feather, feeding, mating and hatching and other activities. There were higher proportions of warning and feather preparation among the activities. Warning was a prominent activity. Feeding was mostly done in mid morning, hatching was never discontinued with rotational duties. Little difference of behaviors was found between male and female during the hatching period. Gender differences were found in proportions of various activities during the breeding period.
Drought periods during XXth century
The drought problem always exists somewhere in the world so that the economy of some nation or nations is always being adversely influenced by this factor. Although drought is a natural component of the climate in arid and semi-arid areas, it can occur in areas, which normally receive adequate precipitation. Available hydro meteorological data indicate droughts have occurred through the last century in Bulgaria and they a part of the climatic cycle on the Balkan Peninsula. The precipitation distribution is one of the basic characteristics of the drought occurrence in a given region. However, the distributions of additional meteorological elements should be also taken into account in order to describe the degree of the climate dryness. For example, the distribution of air temperature is an especially important characteristic for drought classifications. The last years in Bulgaria were drier and warmer than the normals for the period of so-called 'current climate' (1961-1990). Precipitation was approximately 80-85 % less than the normals. Statistical methods were used in order to analyze the long-term variations of precipitation, air temperature. The long-term series of data were smoothed by averages and they were also approximated by means of a polynomial. These methods eliminate the random and short periodical fluctuations of the time series. The Spearman coefficient (r) and the Kendall coefficient (rl) were used in order to investigate the existence of eventual trends. Some quantitative criteria were also used for a comparison of the drought frequency and intensity between different regions and years. As a result of the conducted analysis, the investigated period can be divided to separate sub-periods with duration of 10-15 years. These years are characterized with different moisture conditions. Three periods can be determined during the 20 th century, which are characterized by longer and severe droughts, namely 1902-1913, 1942-1953 and 1982-1994. The drought
Periodic solutions of periodically harvested lotka-volterra systems
Hausrath, Alan R.; Manasevich, Raul F.
2012-01-01
We study a Lotka-Volterra system with periodic harvesting, find sufficient conditions for the existence of periodic solutions with the same period, and, under certain conditions, count the number of such periodic solutions.
Webber, W R; Stone, E C; McDonald, F B; Intriligator, D S; Higbie, P R; Heikkila, B; Lal, N
2012-01-01
We have examined features in the structure of the heliosheath using the fine scale time variations of termination shock particles (TSP) between ~0.5 - 20 MeV and electrons between 2.5-14 MeV measured by the CRS instrument as the V2 spacecraft crossed the heliospheric termination shock in 2007. The very disturbed heliosheath at V2 is particularly noteworthy for strong periodic intensity variations of the TSP just after V2 crossed the termination shock (2007.66) reaching a maximum between 2007.75 and 2008.0. A series of 42/21 day periodicities was observed at V2 along with spectral changes of low energy TSP and the acceleration of 6-14 MeV electrons. Evidence is presented for the acceleration of TSP and electrons at the times of the 42/21 day periodicities just after V2 crossed the HTS. Spectra for TSP between 2-20 MeV and electrons between 2.5-14 MeV are derived for three time periods including the time of the HTS crossing. The energy spectra of TSP and electrons at these times of intensity peaks are very simi...
Periodically kicked turbulence
Lohse
2000-10-01
Periodically kicked turbulence is theoretically analyzed within a mean-field theory. For large enough kicking strength A and kicking frequency f the Reynolds number grows exponentially and then runs into some saturation. The saturation level Re(sat) can be calculated analytically; different regimes can be observed. For large enough Re we find Re(sat) approximately Af, but intermittency can modify this scaling law. We suggest an experimental realization of periodically kicked turbulence to study the different regimes we theoretically predict and thus to better understand the effect of forcing on fully developed turbulence. PMID:11089041
Higher charge periodic monopoles
Maldonado, Rafael
2013-01-01
We consider singly periodic solutions to the SU(2) Bogomolny equations and use the Nahm transform to generate a class of monopoles of charge k>2, thereby extending known results for lower charge chains. Some simple scattering processes are presented and a comparison made with geodesic motion of monopoles in $\\mathbb{R}^3$.
Ayurveda during Abbasid's period.
Husain, S A; Subhaktha, P K
2000-01-01
This is a historical paper which deals with a brief account of Abbasid's period. In this article the existence of Ayurveda in Arab countries, arrival of Ayurvedic physicians to Baghdad, their eminence, authenticity and literary additions in medical field has been studied and presented. PMID:12578013
Periodic paralysis complicating malaria.
Senanayake, N; Wimalawansa, S J
1981-01-01
Episodic muscular weakness, commonly associated with alterations of serum potassium, is the cardinal feature of periodic paralysis. The combination of transient hyperkalaemia and rigors occurring during febrile episodes of malaria is suggested as the underlying cause which precipitated the muscular paralysis. Three patients with malaria who developed a similar paralysis during the paroxysms of fever are described to illustrate this.
Treatment for periodic paralysis
Sansone, [No Value; Meola, G.; Links, T. P.; Panzeri, M.; Rose, M. R.
2008-01-01
Background Primary periodic paralyses are rare inherited muscle diseases characterised by episodes of flaccid weakness affecting one or more limbs, lasting several hours to several days, caused by mutations in skeletal muscle channel genes. Objectives The objective of this review was to systematical
Herrenden-Harker, B. D.
1997-01-01
Presents a modern Periodic Table based on the electron distribution in the outermost shell and the order of filling of the sublevels within the shells. Enables a student to read off directly the electronic configuration of the element and the order in which filling occurs. (JRH)
Johnson, Mike
1998-01-01
Presents an exercise in which an eighth-grade science teacher decorated the classroom with a periodic table of students. Student photographs were arranged according to similarities into vertical columns. Students were each assigned an atomic number according to their placement in the table. The table is then used to teach students about…
Almost periodic Schroedinger operators
These lectures are devoted to recent developments in the theory of almost-periodic Schroedinger Operators. We specially describe the algebraic point of view, with applications to gap-labelling theorems. Particular models are also presented which exhibit various spectral properties. (orig.)
Williamson, Ronald
2010-01-01
Driven by stable or declining financial resources many school districts are considering the costs and benefits of a seven-period day. While there is limited evidence that any particular scheduling model has a greater impact on student learning than any other, it is clear that the school schedule is a tool that can significantly impact teacher…
Time discounting and time consistency
Dimitri, N.; Eijck, van, Jan
2012-01-01
Time discounting is the phenomenon that a desired result in the future is perceived as less valuable than the same result now. Economic theories can take this psychological fact into account in several ways. In the economic literature the most widely used type of additive time discounting is {\\em exponential discounting}. In exponential discounting, the fall of valuation depends by a constant factor on the length of the delay period. It is well known, however, that exponential time discountin...
Time Discounting and Time Consistency
Dimitri, N.; Eijck, van, Jan
2011-01-01
Time discounting is the phenomenon that a desired result in the future is perceived as less valuable than the same result now. Economic theories can take this psychological fact into account in several ways. In the economic literature the most widely used type of additive time discounting is exponential discounting. In exponential discounting, the fall of valuation depends by a constant factor on the length of the delay period. It is well known, however, that exponential time discounting ofte...
Automatically identifying periodic social events from Twitter
Kunneman, F.A.; Bosch, A.P.J. van den
2015-01-01
Many events referred to on Twitter are of a periodic nature, characterized by roughly constant time intervals in between occurrences. Examples are annual music festivals, weekly television programs, and the full moon cycle. We propose a system that can automatically identify periodic events from Twi
Nonlinear quasimodes near elliptic periodic geodesics
Albin, Pierre; Marzuola, Jeremy L; Thomann, Laurent
2011-01-01
We consider the nonlinear Schr\\"odinger equation on a compact manifold near an elliptic periodic geodesic. Using a geometric optics construction, we construct quasimodes to a nonlinear stationary problem which are highly localized near the periodic geodesic. We show the nonlinear Schr\\"odinger evolution of such a quasimode remains localized near the geodesic, at least for short times.
高巧琴; 雒志江
2011-01-01
A competitive system was studied that has a discrete delay stage-structure and cannibalism, where one of the species has two stages, an immature stage and a mature stage. By means of the continuous theorem of coincidence degree theory,a sufficient condition is obtained for the existence of a positive periodic solution of the system when cannibalism occurs.%研究了一类具有时滞和自食的非自治阶段结构竞争系统的动力学行为,其中一种群分幼年和成年两个阶段.当发生自食现象时,利用重合度理论中的延拓定理,得到该系统正周期解存在的充分条件.
The Detection of Hidden Periodicities in EEG
YOU Rong-yi
2007-01-01
Abstract.A novel method for detecting the hidden periodicities in EEG is proposed.By using a width-varying window in the time domain, the structure function of EEG time series is defined. It is found that the minima of the structure function, within a finite window width, can be found regularly, which indicate that there are some certain periodicities associated with EEG time series. Based on the structure function, a further quadratic structure function of EEG time series is defined. By quadratic structure function, it can be seen that the periodicities of EEG become more obvious, moreover, the period of EEG can be determined accurately. These results will be meaningful for studying the neuron activity inside the human brain.
Coping with Common Period Problems (For Teens)
... and your period — is excessive exercising , usually distance running, ballet, or gymnastics, combined with a poor diet. For exercise to be excessive, it means more than just playing soccer a few times a week or working out ...
Bakas, Ioannis
2002-01-01
We consider static solutions of the sine-Gordon theory defined on a cylinder, which can be either periodic or quasi-periodic in space. They are described by the different modes of a simple pendulum moving in an inverted effective potential and correspond to its libration or rotation. We review the decomposition of the solutions into an oscillatory sum of alternating kinks and anti-kinks or into a monotonic train of kinks, respectively, using properties of elliptic functions. The two sectors are naturally related to each other by a modular transformation, whereas the underlying spectral curve of the model can be used to express the energy of the static configurations in terms of contour integrals \\`a la Seiberg-Witten in either case. The stability properties are also examined by means of supersymmetric quantum mechanics, where we find that the unstable configurations are associated to singular superpotentials, thus allowing for negative modes in the spectrum of small fluctuations.
A case of thyrotoxic periodic paralysis is reported in a Hispanic man with an unusual recurrence six weeks after radioactive iodine treatment. Thyrotoxic periodic paralysis has now been well characterized in the literature: it occurs primarily in Orientals with an overwhelming male preponderance and a higher association of specific HLA antigens. Clinical manifestations include onset after high carbohydrate ingestion or heavy exertion, with progressive symmetric weakness leading to flaccid paralysis of the extremities and other muscle groups, lasting several hours. If hypokalemia is present, potassium administration may help abort the attack. Although propranolol can be efficacious in preventing further episodes, the only definitive treatment is establishing a euthyroid state. The pathophysiology is still controversial, but reflects altered potassium and calcium dynamics as well as certain morphologic characteristics within the muscle unit itself
Hypokalemic periodic paralysis
Abbas, Haider; Kothari, Nikhil; Bogra, Jaishri
2012-01-01
Hypokalemic periodic paralysis is a rare genetic disorder characterized by recurrent attacks of skeletal muscle weakness with associated hypokalemia which is precipitated by stress, cold, carbohydrate load, infection, glucose infusion, hypothermia, metabolic alkalosis, anesthesia, and steroids. We encountered one such incidence of prolonged recovery after general anesthesia, which on further evaluation revealed a case of hypokalemic paralysis. The key to successful management of such a patien...
Scattering of periodic solitons
Cova, R.J. [Carleton University, School of Mathematics and Statistics, 1125 Colonel by Drive, Ottawa, Ontario K1S 5B6 (Canada); Zakrzewski, W.J. [University of Durham, Dept. of Mathematical Sciences, Durham DH1 3LE (United Kingdom)]. e-mail: rcova@math.carleton.ca
2004-07-01
Through numerical simulations we study N-soliton scattering (N = 3, 4) in the (2 + 1)-dimensional CP{sup 1} model with periodic boundary conditions. Solitons colliding from symmetrical configurations scatter at {pi}/ N, as observed in the usual model with standard boundary conditions. When the initial configurations are not symmetric the angles differ from {pi}/ N. We describe our observed patterns based on a properly formulated geodesic approximation. (Author) 11 refs., 10 figs.
Pasham, Dheeraj R
2013-01-01
Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1 we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its hardness ratio (5-10 keV/3-5 keV), an indicator of the energy spectral power-law index. When stellar-mass black holes (StMBHs) exhibit Type-C low-frequency QPOs (~ 0.2-15 Hz) the centroid frequency of the QPO is known to correlate with the energy spectral index. The detection of such a correlation would strengthen the identification of M82 X-1's mHz QPOs as Type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of Type-C QPOs in StMBHs of known mass. We resolved the count rates and the hardness ratios of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling. We detected QPOs in the frequency range of 36-210 mHz during which M82 X-1's hardness ratio varied from 0.42-0.47. Our primary results are: (1) we do not detect any correlati...
Periodic Mesoporous Organosilica Nanorice
Mohanty Paritosh
2008-01-01
Full Text Available Abstract A periodic mesoporous organosilica (PMO with nanorice morphology was successfully synthesized by a template assisted sol–gel method using a chain-type precursor. The PMO is composed of D and T sites in the ratio 1:2. The obtained mesoporous nanorice has a surface area of 753 m2 g−1, one-dimensional channels, and a narrow pore size distribution centered at 4.3 nm. The nanorice particles have a length of ca. 600 nm and width of ca. 200 nm.
Polysheroidal periodic functions
Separation of variables in the Helmholtz N-dimensional (N≥4) equation in polyspheroidal coordinate systems leads to the necessity of solving equations going over into equations for polyspheroidal periodic functions used for solving the two-centre problem in quantum mechanics, the three-body problem with Coulomb interaction, etc. For these functions the expansions are derived in terms of the Jacobi polynomials and Bessel functions. Their basic properties, asymptotics are considered. The algorithm of their computer calculations is developed. The results of numerical calculations are given
Scattering of periodic solitons
Cova, R J
2003-01-01
With the help of numerical simulations we study N-soliton scattering (N=3,4) in the (2+1)-dimensional CP^1 model with periodic boundary conditions. When the solitons are scattered from symmetrical configurations the scattering angles observed agree with the earlier \\pi/N predictions based on the model on R_2 with standard boundary conditions. When the boundary conditions are not symmetric the angles are different from \\pi/N. We present an explanation of our observed patterns based on a properly formulated geodesic approximation.
Nester, K. [Forschungzentrum Karlsruhe (Germany). Inst. fuer Meteorologie und Klimaforschung
1997-12-31
Polycyclic aromatic hydrocarbons (PAHs) belong to the group of environmentally hazardous substances because of their cancerogenous effect. They occur both as gases and in particulate form and are released by man into the atmosphere as combustion products. They play a role not only in the atmosphere but also in soil. An essential process permitting these substances to penetrate into the soil is by deposition from the atmosphere.- The study had the aim of assessing atmospheric PAH deposition to the soil. The outcome is used to simulate PAH behaviour in soil, a task which also forms part of the interlaboratory project `soil`. As PAHs are regularly measured only in a few places, PAH transfer from atmosphere to soil needs to be numerically modelled. That the model can do this was first of all to be demonstrated for a short period. The result is described in the paper. Subsequently, statements regarding long-term PAH transfer are attempted. (orig.) [Deutsch] Die Polycyklischen Aromatischen Kohlenwasserstoffe (PAK) gehoeren wegen ihrer kanzerogenen Wirkungen zu den umweltbelastenden Substanzen. Sie treten sowohl als Gase als auch als Partikel auf und werden antropogen als Verbrennungsprodukte in die Atmosphaere freigesetzt. Neben ihrer Wirkung in der Atmosphaere spielen sie im Boden eine Rolle. Ein wesentlicher Prozess, der diese Substanzen in den Boden gelangen laesst, ist die Deposition aus der Atmosphaere zum Boden. Ziel der Untersuchungen war es, den atmosphaerischen Eintrag der PAK in den Boden zu bestimmen. Dieser Eintrag dient der Simulation des Verhaltens der PAK im Boden, der ebenfalls Bestandteil des Verbundprojekts `Boden` war. Da es nur wenige Stellen gibt, an denen regelmaessig PAK`s gemessen werden, ist es notwendig, den PAK Eintrag aus der Atmosphaere zum Boden mittels Modellrechnungen abzuschaetzen. Dabei sollte zunaechst fuer eine kurze Episode gezeigt werden, dass das Modell in der Lage ist, dies zu leisten. Dieses Ergebnis wird im folgenden vorgestellt
Quasi Periodic Oscillations in Blazars
Alok C. Gupta
2014-09-01
Here we report our recent discoveries of Quasi-Periodic Oscillations (QPOs) in blazars time series data in X-ray and optical electromagnetic bands. Any such detection can give important clues of the location and nature of the processes of emission mechanism. In the case of radio-quiet AGN, the detected QPOs are very likely to be associated with the accretion disk. But in the case of blazars, it may be associated with jets in the high and outburst states, and in the low-state, it is probably associated with the accretion disk. In this brief review, I summarize the recent QPO detections in blazars. There is one strong evidence of QPO detection in XMM–Newton time series data of narrow line Seyfert 1 galaxy RE J1034+396 about which we will also discuss briefly.
黄小珊; 刘康
2011-01-01
兼职班主任是高校思想政治教育工作队伍的重要组成部分。文章从工作实际出发,阐述兼职班主任在新生入学教育中的工作重点和内容,坚持班主任＂以育人为中心＂的工作目标,处理好专业和兼职的关系,明确贴心＂保姆＂、知心朋友、实干领导等三种角色,把握工作准备期、感情培养期、学习交流期、工作小结期等四个阶段,引导新生树立责任意识、学习观念、学习方法、人际交往和生活习惯等五个目标。%Part-time class advisors weigh an important role in the ideological and political education in those top universities. This paper would like to elaborate on the key points and some details of their work from a practical perspective. Class advisors need to set their goals as ＂putting people＇s education to the first place＂,compromise their work between full-time job and part-time job,deal with their relations with students as considerate nurses,bosom friends,and capable leaders. If they take full advantage of the following four phases：working preparation,emotion cultivation,study exchanges and working summary,it will help them to guide students how to set up responsible consciousness,learning ideas,learning methods, interpersonal communication ,living habits and some more goals.
Grazyna Wójcik
2008-04-01
Full Text Available To date, there has been little research examining whether short-time changes of external environmental conditions exert any effects on immune responses. The activation of metabolic changes, release of hormones responsive for immunomodulation and the action of interleukins play an important role in interaction with hormones of an anterior pituitary gland in the proestrous phase of the reproductive cycle. The aim of our study was to determine the effects of a short-time change of ambient temperature (30 minutes on interleukin-6 (IL-6 and corticosterone plasma concentration of female rats in the proestrous phase of the reproductive cycle. The climatic chamber with automatically adjustable and monitored internal environmental parameters (temperature, oxygenation, humidity was used during the experiment. The estimation of the vaginal lavage using a microscope was done to determine the estrous cycle. On the day of the experiment, animals were divided into 2 groups: the control group (ambient temperature 21 degrees C +/- 1 degrees C; normoxia 21% O2 and the test group (ambient temperature 10 degrees C +/- 1 degrees C; normoxia 21% O2 stayed in the climatic chamber for 30 minutes. The blood samples were collected before the experiment and after 30, 60, 90, 150 and 210 minutes from the beginning of the experiment. The concentrations of IL-6 and corticosterone were measured in blood plasma samples using ELISA method. There was a significant elevation of IL-6 levels after staying in 10 degrees C during the first 150 minutes from the beginning of the experiment, with the highest value occurring after 60 minutes (426.6 pg/ml; SE - 146.1 with comparison to the value at first sampling (108.5 pg/ml; SE - 29.5; p<0.05 and with comparison to the control group at the same time from the beginning of the experiment (87.6 pg/ml; SE - 2.3; p<0.05. The changed level of corticosterone in the test group in comparison to control group was observed but the differences were
Pasham, Dheeraj R.; Strohmayer, Tod E.
2013-01-01
Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X-1, we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its hardness ratio (5-10 keV/3-5 keV), an indicator of the energy spectral power-law index. When stellar-mass black holes (StMBHs) exhibit type-C low-frequency QPOs (0.2-15 Hz), the centroid frequency of the QPO is known to correlate with the energy spectral index. The detection of such a correlation would strengthen the identification of M82 X-1's mHz QPOs as type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of type-C QPOs in StMBHs of known mass.We resolved the count rates and the hardness ratios of M82 X-1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling.We detected QPOs in the frequency range of 36-210 mHz during which M82 X-1's hardness ratio varied from 0.42 to 0.47. Our primary results are (1) that we do not detect any correlation between the mHz QPO frequency and the hardness ratio (a substitute for the energy spectral power-law index) and (2) similar to some accreting X-ray binaries, we find that M82 X-1's mHz QPO frequency increases with its X-ray count rate (Pearson's correlation coefficient = +0.97). The apparent lack of a correlation between the QPO centroid frequency and the hardness ratio poses a challenge to the earlier claims that the mHz QPOs of M82 X-1 are the analogs of the type-C low-frequency QPOs of StMBHs. On the other hand, it is possible that the observed relation between the hardness ratio and the QPO frequency represents the saturated portion of the correlation seen in type-C QPOs of StMBHs-in which case M82 X-1's mHz QPOs can still be analogous to type-C QPOs.
Using all the archival XMM-Newton X-ray (3-10 keV) observations of the ultraluminous X-ray source (ULX) M82 X–1, we searched for a correlation between its variable mHz quasi-periodic oscillation (QPO) frequency and its hardness ratio (5-10 keV/3-5 keV), an indicator of the energy spectral power-law index. When stellar-mass black holes (StMBHs) exhibit type-C low-frequency QPOs (∼0.2-15 Hz), the centroid frequency of the QPO is known to correlate with the energy spectral index. The detection of such a correlation would strengthen the identification of M82 X–1's mHz QPOs as type-C and enable a more reliable mass estimate by scaling its QPO frequencies to those of type-C QPOs in StMBHs of known mass. We resolved the count rates and the hardness ratios of M82 X–1 and a nearby bright ULX (source 5/X42.3+59) through surface brightness modeling. We detected QPOs in the frequency range of 36-210 mHz during which M82 X–1's hardness ratio varied from 0.42 to 0.47. Our primary results are (1) that we do not detect any correlation between the mHz QPO frequency and the hardness ratio (a substitute for the energy spectral power-law index) and (2) similar to some accreting X-ray binaries, we find that M82 X–1's mHz QPO frequency increases with its X-ray count rate (Pearson's correlation coefficient = +0.97). The apparent lack of a correlation between the QPO centroid frequency and the hardness ratio poses a challenge to the earlier claims that the mHz QPOs of M82 X–1 are the analogs of the type-C low-frequency QPOs of StMBHs. On the other hand, it is possible that the observed relation between the hardness ratio and the QPO frequency represents the saturated portion of the correlation seen in type-C QPOs of StMBHs—in which case M82 X–1's mHz QPOs can still be analogous to type-C QPOs.
Periods and Superstring Amplitudes
Stieberger, S
2016-01-01
Scattering amplitudes which describe the interaction of physical states play an important role in determining physical observables. In string theory the physical states are given by vibrations of open and closed strings and their interactions are described (at the leading order in perturbation theory) by a world-sheet given by the topology of a disk or sphere, respectively. Formally, for scattering of N strings this leads to N-3-dimensional iterated real integrals along the compactified real axis or N-3-dimensional complex sphere integrals, respectively. As a consequence the physical observables are described by periods on M_{0,N} - the moduli space of Riemann spheres of N ordered marked points. The mathematical structure of these string amplitudes share many recent advances in arithmetic algebraic geometry and number theory like multiple zeta values, single-valued multiple zeta values, Drinfeld, Deligne associators, Hopf algebra and Lie algebra structures related to Grothendiecks Galois theory. We review the...
Smetanová, Anna; Verstraeten, Gert; Nyens, Gerda; Notebaert, Bastiaan; Szwarczewski, Piotr; Čurlík, Ján; Burian, Libor; Kazeminejad, Seyed Ali; Létal, Aleš; Dotterweich, Markus
2015-04-01
Since the onset of agriculture the erosion processes - water, tillage and wind erosion - have dominated the soil degradation and the loss of soil resources in the agricultural landscapes worldwide. Their influence has varied within time and spatial scales according to changing environmental and societal factors, including human-induced landscape design. The Holocene landforms transformation in a zero-order catchment of a dry valley (0.28 km2) in the Chernozem region of the South-West Foreland of the West Carpathians was studied. The analyses of geoarchives and spatial patterns of soil profile truncation and colluviation were performed and the historical field border structure reconstructed. The results showed strong relationship between the long-term soil erosion pattern and landscape sructure in areas with stable historical landscape structure. It favored the prevalence of tillage erosion and tillage induced soil translocation and minimized the fluxes and sediment delivery of wind and water erosion. The erosion of the entire 0,6 m thick humus horizon by tillage was documented during historical times. The intensification of agriculture since the mid -18th Century led to the change in field borders and thus shifted the long-term fluxes of soil translocation. The most profound changes were connected to the collectivization of agriculture since 1950's, when the entire catchment became part of one field and heavy machinery started to be applied. The general contour direction of the tillage decreased locally the down-slope tillage translocation, but became parallel to flow direction in the valley bottom and to the two main dominant wind directions. The areas with a significant proportion of parent material (loess) in the tillage horizon increased almost four-fold in 50 years. They are similarly to the older ones localized in the upper-slope position, but they spread to concavities and less steep slope gradients. It implied that the change of tillage direction in
刘学英; 廖倩; 周华; 吴娟; 邓雪雁; 唐义英; 汪丽萍; 万雨莉; 胡鸽
2016-01-01
Objective:To investigate the suitable replacement time of colostomy stoma chassis during hospitaliza-tion.Methods:A total of 156 cases of colostomy patients using simple random sampling method were divided in-to A,B,C three groups,with the stoma chassis replacement interval of three days,five days,seven days respec-tively.Observation and comparison were conducted on the skin condition around the periosteal wound,DET score and the feeling of patients.Results:According to the comparison of the width of impregnated chassis,con-dition of leakage,probability of skin complications,DET score and the material expenses of these three sample groups,results of group B is better than that of group C(P 0.05).Conclusion:Under the standardized nursing procedure,the interval of five days is the most appropriate time for colostomy stoma patient to replace stoma chassis.It can reduce the probability of skin complications around stoma and make patient feel more comfortable during treatment.%[目的]探讨结肠造口病人住院期间造口底盘更换的适宜时间。[方法]采取单纯随机抽样方法将156例结肠造口病人分为 A组、B 组、C 组，分别间隔3 d、5 d、7 d 更换1次造口底盘，观察其效果并比较造口周围皮肤状况、病人对造口的自我感受情况。[结果]B 组底盘浸渍宽度、渗漏、造口周围皮肤并发症及造口材料费用等均优于 C 组(P 0.05)。[结论]结肠造口病人住院期间造口底盘更换间隔时间以5 d 为宜；标准的造口护理流程和适宜的造口底盘更换时间，能减少造口周围皮肤并发症的发生，病人感觉更舒适。
Geometry of Periodic Monopoles
Maldonado, Rafael
2013-01-01
BPS monopoles on $\\mathbb{R}^2\\timesS^1$ correspond, via the generalized Nahm transform, to certain solutions of the Hitchin equations on the cylinder $\\mathbb{R}\\times S^1$. The moduli space M of two monopoles with their centre-of-mass fixed is a 4-dimensional manifold with a natural hyperk\\"ahler metric, and its geodesics correspond to slow-motion monopole scattering. The purpose of this paper is to study the geometry of M in terms of the Nahm/Hitchin data, i.e. in terms of structures on $\\mathbb{R}\\times S^1$. In particular, we identify the moduli, derive the asymptotic metric on M, and discuss several geodesic surfaces and geodesics on M. The latter include novel examples of monopole dynamics.