Energy Technology Data Exchange (ETDEWEB)
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.
First passage times: Busy periods and waiting times
Institute of Scientific and Technical Information of China (English)
徐光煇; 袁学明
1995-01-01
General expressions of first passage times for denumerable Markov processes are discussed and computation problems for busy periods and waiting times for queues corresponding to Markov processes are studied. In particular, the simplified algorithms for busy periods and waiting times for queues corresponding to G//M/1 type and M/G/1 type Markov processes are derived and some numerical examples are presented.
Forecasting with periodic autoregressive time series models
Ph.H.B.F. Franses (Philip Hans); R. Paap (Richard)
1999-01-01
textabstractThis paper is concerned with forecasting univariate seasonal time series data using periodic autoregressive models. We show how one should account for unit roots and deterministic terms when generating out-of-sample forecasts. We illustrate the models for various quarterly UK consumption
Directory of Open Access Journals (Sweden)
Yongkun Li
2011-01-01
Full Text Available Firstly, we propose a concept of uniformly almost periodic functions on almost periodic time scales and investigate some basic properties of them. When time scale T=ℝ or ℤ, our definition of the uniformly almost periodic functions is equivalent to the classical definitions of uniformly almost periodic functions and the uniformly almost periodic sequences, respectively. Then, based on these, we study the existence and uniqueness of almost periodic solutions and derive some fundamental conditions of admitting an exponential dichotomy to linear dynamic equations. Finally, as an application of our results, we study the existence of almost periodic solutions for an almost periodic nonlinear dynamic equations on time scales.
On periodic orbits in discrete-time cascade systems
Directory of Open Access Journals (Sweden)
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.
Mining approximate periodic pattern in hydrological time series
Zhu, Y. L.; Li, S. J.; Bao, N. N.; Wan, D. S.
2012-04-01
There is a lot of information about the hidden laws of nature evolution and the influences of human beings activities on the earth surface in long sequence of hydrological time series. Data mining technology can help find those hidden laws, such as flood frequency and abrupt change, which is useful for the decision support of hydrological prediction and flood control scheduling. The periodic nature of hydrological time series is important for trend forecasting of drought and flood and hydraulic engineering planning. In Hydrology, the full period analysis of hydrological time series has attracted a lot of attention, such as the discrete periodogram, simple partial wave method, Fourier analysis method, and maximum entropy spectral analysis method and wavelet analysis. In fact, the hydrological process is influenced both by deterministic factors and stochastic ones. For example, the tidal level is also affected by moon circling the Earth, in addition to the Earth revolution and its rotation. Hence, there is some kind of approximate period hidden in the hydrological time series, sometimes which is also called the cryptic period. Recently, partial period mining originated from the data mining domain can be a remedy for the traditional period analysis methods in hydrology, which has a loose request of the data integrity and continuity. They can find some partial period in the time series. This paper is focused on the partial period mining in the hydrological time series. Based on asynchronous periodic pattern and partial period mining with suffix tree, this paper proposes to mine multi-event asynchronous periodic pattern based on modified suffix tree representation and traversal, and invent a dynamic candidate period intervals adjusting method, which can avoids period omissions or waste of time and space. The experimental results on synthetic data and real water level data of the Yangtze River at Nanjing station indicate that this algorithm can discover hydrological
Satisfactory control of discrete-time linear periodic systems
Institute of Scientific and Technical Information of China (English)
Shiqian LIU; Jihong ZHU; JinChun HU
2007-01-01
In this paper satisfactory control for discrete-time linear periodic systems is studied.Based on a suitable time-invariant state sampled reformulation,periodic state feedback controller has been designed such that desired requirements of steady state covariance,H-infinity rejection bound and regional pole assignment for the periodic system are met simultaneously.By using satisfactory control theory,the problem of satisfactory periodic controller can be transformed into a linear programming problem subject to a set of linear matrix inequalities(LMIs).and a feasible designing approach is presented via LMI technique.Numeric example validates the obtained conclusion.
Periodicity Estimation in Mechanical Acoustic Time-Series Data
Directory of Open Access Journals (Sweden)
Zhu Yongbo
2015-01-01
Full Text Available Periodicity estimation in mechanical acoustic time-series data is a well-established problem in data mining as it can be applicable in variety of disciplines either for anomaly detection or for prediction purposes in industry. In this paper, we develop a new approach for capturing and characterizing periodic patterns in time-series data by virtue of the dynamic time warping (DTW. We have conducted extensive experiments to evaluate the proposed approach with synthetic data and our collected data in practice. Experimental results demonstrated its effectiveness and robustness on periodicity detection in highly noised data.
Energy Technology Data Exchange (ETDEWEB)
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.
A time-periodic reaction-diffusion epidemic model with infection period
Zhang, Liang; Wang, Zhi-Cheng
2016-10-01
In this paper, we propose a time-periodic and diffusive SIR epidemic model with constant infection period. By introducing the basic reproduction number R_0 via a next generation operator for this model, we show that the disease goes extinction if R_0 1.
Periodic flows to chaos in time-delay systems
Luo, Albert C J
2017-01-01
This book for the first time examines periodic motions to chaos in time-delay systems, which exist extensively in engineering. For a long time, the stability of time-delay systems at equilibrium has been of great interest from the Lyapunov theory-based methods, where one cannot achieve the ideal results. Thus, time-delay discretization in time-delay systems was used for the stability of these systems. In this volume, Dr. Luo presents an accurate method based on the finite Fourier series to determine periodic motions in nonlinear time-delay systems. The stability and bifurcation of periodic motions are determined by the time-delayed system of coefficients in the Fourier series and the method for nonlinear time-delay systems is equivalent to the Laplace transformation method for linear time-delay systems. Facilitates discovery of analytical solutions of nonlinear time-delay systems; Illustrates bifurcation trees of periodic motions to chaos; Helps readers identify motion complexity and singularity; Explains pro...
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
Return times at periodic points in random dynamics
Haydn, Nicolai; Todd, Mike
2017-01-01
We prove a quenched limiting law for random measures on subshifts at periodic points. We consider a family of measures {≤ft\\{{{μω}\\right\\}}ω \\in Ω } , where the ‘driving space’ Ω is equipped with a probability measure which is invariant under a transformation θ. We assume that the fibred measures {μω} satisfy a generalised invariance property and are ψ-mixing. We then show that for almost every ω the return times to cylinders A n at periodic points are in the limit compound Poisson distributed for a parameter ϑ which is given by the escape rate at the periodic point.
Extracting unstable periodic orbits from chaotic time series data
Energy Technology Data Exchange (ETDEWEB)
So, P.; Schiff, S.; Gluckman, B.J., [Center for Neuroscience, Childrens Research Institute, Childrens National Medical Center and the George Washington University, NW, Washington, D.C. 20010 (United States); So, P.; Ott, E.; Grebogi, C., [Institute for Plasma Research, University of Maryland, College Park, Maryland 20742 (United States); Sauer, T., [Department of Mathematics, The George Mason University, Fairfax, Virginia 22030 (United States); Gluckman, B.J., [Naval Surface Warfare Center, Carderock Division, Bethesda, Maryland 20054-5000 (United States)
1997-05-01
A general nonlinear method to extract unstable periodic orbits from chaotic time series is proposed. By utilizing the estimated local dynamics along a trajectory, we devise a transformation of the time series data such that the transformed data are concentrated on the periodic orbits. Thus, one can extract unstable periodic orbits from a chaotic time series by simply looking for peaks in a finite grid approximation of the distribution function of the transformed data. Our method is demonstrated using data from both numerical and experimental examples, including neuronal ensemble data from mammalian brain slices. The statistical significance of the results in the presence of noise is assessed using surrogate data. {copyright} {ital 1997} {ital The American Physical Society}
Infrared Variability and Time Lags for Periodic Quasars
Jun, Hyunsung David; Stern, Daniel; Graham, Matthew J.; Djorgovski, Stanislav G.; Mainzer, Amy; Cutri, Roc M.; Drake, Andrew J.; Mahabal, Ashish A.
2017-01-01
The optical light curve of the quasar PG 1302-102 at z=0.278 shows a 5.2 year periodic signal, detectable over a period of 20 years. The most plausible mechanisms involve a binary supermassive black hole system with a sub-pc separation, where they will likely merge within ~10^5 years due to gravitational wave emission alone. Here, we report the infrared time lags for PG 1302-102 from WISE and Akari missions. We confirm that the periodic behavior reported in the optical light curve is reproduced at infrared, with best-fit 3.4 and 4.6 micron 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 time lag to the optical 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 ~1.1-1.3 pc away. We briefly mention ongoing works to constrain the infrared variability and time lags for all the identified periodic quasars, and to relate the quantities to physical origins.
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 ...
Optimal periodic orbits of continuous time chaotic systems
Yang; Hunt; Ott
2000-08-01
In previous work [B. R. Hunt and E. Ott, Phys. Rev. Lett. 76, 2254 (1996); Phys. Rev. E 54, 328, (1996)], based on numerical experiments and analysis, it was conjectured that the optimal orbit selected from all possible orbits on a chaotic attractor is "typically" a periodic orbit of low period. By an optimal orbit we mean the orbit that yields the largest value of a time average of a given smooth "performance" function of the system state. Thus optimality is defined with respect to the given performance function. (The study of optimal orbits is of interest in at least three contexts: controlling chaos, embedding of low-dimensional attractors of high-dimensional dynamical systems in low-dimensional measurement spaces, and bubbling bifurcations of synchronized chaotic systems.) Here we extend this previous work. In particular, the previous work was for discrete time dynamical systems, and here we shall consider continuous time systems (flows). An essential difference for flows is that chaotic attractors can have embedded within them, not only unstable periodic orbits, but also unstable steady states, and we find that optimality can often occur on steady states. We also shed further light on the sense in which optimality is "typically" achieved at low period. In particular, we find that, as a system parameter is tuned to be closer to a crisis of the chaotic attractor, optimality may occur at higher period.
Variable time-period optical switching: a novel OBS implementation
Institute of Scientific and Technical Information of China (English)
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.
Pseudo analytical solution to time periodic stiffness systems
Institute of Scientific and Technical Information of China (English)
Wang Yan-Zhong; Zhou Yuan-Zi
2011-01-01
An analytical form of state transition matrix for a system of equations with time periodic stiffness is derived in order to solve the free response and also allow for the determination of system stability and bifurcation. A pseudoclosed form complete solution for parametrically excited systems subjected to inhomogeneous generalized forcing is developed, based on the Fourier expansion of periodic matrices and the substitution of matrix exponential terms via Lagrange-Sylvester theorem. A Mathieu type of equation with large amplitude is presented to demonstrate the method of formulating state transition matrix and Floquet multipliers. A two-degree-of-freedom system with irregular time periodic stiffness characterized by spiral bevel gear mesh vibration is presented to find forced response in stability and instability. The obtained results are presented and discussed.
Analysis of time-domain scattering by periodic structures
Gao, Yixian; Li, Peijun
2016-11-01
This paper is devoted to the mathematical analysis of a time-domain electromagnetic scattering by periodic structures which are known as diffraction gratings. The scattering problem is reduced equivalently into an initial-boundary value problem in a bounded domain by using an exact transparent boundary condition. The well-posedness and stability of the solution are established for the reduced problem. Moreover, a priori energy estimates are obtained with minimum regularity requirement for the data and explicit dependence on the time.
Physical characters of KLS time-periodic universe
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In this paper we consider the physical characters of the new time-periodic solution of the vacuum Einstein’s field equations which was constructed by Kong, Liu and Shen. By the analysis of the Penrose diagram associated with this solution, we find that this solution is very different from the other solutions.
Physical Activity in High School during "Free-Time" Periods
Silva, Pedro; Sousa, Michael; Sá, Carla; Ribeiro, José; Mota, Jorge
2015-01-01
The purpose of this study was to examine youth physical activity (PA) in free-time periods during high school days and their contribution to total PA. Differences in terms of sex, age, body mass index and school level were assessed in a sample of Portuguese adolescents. Participants totalled 213 (135 girls), aged 14.6 ± 1.7, from two different…
Behaviour of time-dependent materials exposed to periodical loading
Directory of Open Access Journals (Sweden)
Zupancic B.
2010-06-01
Full Text Available Paper presents methodology for analyzing behaviour of time-dependent (viscoelastic materials when exposed to periodical (cyclic loading. Within each loading cycle time-dependent material undergoes a combination of the creep and retardation process. At certain conditions the retardation process between two loading cycles cannot be fully completed to a strain free state. Consequently, strain starts to accumulate, which leads to hardening of the material and ultimately to the failure of polymeric product. Critical frequency of the applied periodical loading depends on the material retardation time (location of mechanical spectrum, while the magnitude of accumulated strain on the strength of corresponding discrete spectrum lines. The shape of mechanical spectrum defines the intensity and the magnitude of accumulated strain. Thus, the mechanical spectrum of time-dependent material is the most important function for predicting durability of dynamically loaded polymeric products. In continuation we present mathematical methodology for predicting durability of periodically loaded polymeric components of drive belt. Methodology includes numerical calculations of accumulated strain as a function of the number of loading cycles and function of loading angular velocity. Based on these calculations we can determine the critical angular velocity area of periodical loading where the strain accumulation is the most intensive.
Time-periodic solutions of the Benjamin-Ono equation
Energy Technology Data Exchange (ETDEWEB)
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.
A method for obtaining time-periodic Lp estimates
Kyed, Mads; Sauer, Jonas
2017-01-01
We introduce a method for showing a prioriLp estimates for time-periodic, linear, partial differential equations set in a variety of domains such as the whole space, the half space and bounded domains. The method is generic and can be applied to a wide range of problems. We demonstrate it on the heat equation. The main idea is to replace the time axis with a torus in order to reformulate the problem on a locally compact abelian group and to employ Fourier analysis on this group. As a by-product, maximal Lp regularity for the corresponding initial-value problem follows without the notion of R-boundedness. Moreover, we introduce the concept of a time-periodic fundamental solution.
Periodic, Quasi-periodic and Chaotic Dynamics in Simple Gene Elements with Time Delays
Suzuki, Yoko; Lu, Mingyang; Ben-Jacob, Eshel; Onuchic, José N.
2016-02-01
Regulatory gene circuit motifs play crucial roles in performing and maintaining vital cellular functions. Frequently, theoretical studies of gene circuits focus on steady-state behaviors and do not include time delays. In this study, the inclusion of time delays is shown to entirely change the time-dependent dynamics for even the simplest possible circuits with one and two gene elements with self and cross regulations. These elements can give rise to rich behaviors including periodic, quasi-periodic, weak chaotic, strong chaotic and intermittent dynamics. We introduce a special power-spectrum-based method to characterize and discriminate these dynamical modes quantitatively. Our simulation results suggest that, while a single negative feedback loop of either one- or two-gene element can only have periodic dynamics, the elements with two positive/negative feedback loops are the minimalist elements to have chaotic dynamics. These elements typically have one negative feedback loop that generates oscillations, and another unit that allows frequent switches among multiple steady states or between oscillatory and non-oscillatory dynamics. Possible dynamical features of several simple one- and two-gene elements are presented in details. Discussion is presented for possible roles of the chaotic behavior in the robustness of cellular functions and diseases, for example, in the context of cancer.
Periodic, Quasi-periodic and Chaotic Dynamics in Simple Gene Elements with Time Delays.
Suzuki, Yoko; Lu, Mingyang; Ben-Jacob, Eshel; Onuchic, José N
2016-02-15
Regulatory gene circuit motifs play crucial roles in performing and maintaining vital cellular functions. Frequently, theoretical studies of gene circuits focus on steady-state behaviors and do not include time delays. In this study, the inclusion of time delays is shown to entirely change the time-dependent dynamics for even the simplest possible circuits with one and two gene elements with self and cross regulations. These elements can give rise to rich behaviors including periodic, quasi-periodic, weak chaotic, strong chaotic and intermittent dynamics. We introduce a special power-spectrum-based method to characterize and discriminate these dynamical modes quantitatively. Our simulation results suggest that, while a single negative feedback loop of either one- or two-gene element can only have periodic dynamics, the elements with two positive/negative feedback loops are the minimalist elements to have chaotic dynamics. These elements typically have one negative feedback loop that generates oscillations, and another unit that allows frequent switches among multiple steady states or between oscillatory and non-oscillatory dynamics. Possible dynamical features of several simple one- and two-gene elements are presented in details. Discussion is presented for possible roles of the chaotic behavior in the robustness of cellular functions and diseases, for example, in the context of cancer.
Time-Periodic Einstein--Klein--Gordon Bifurcations of Kerr
Chodosh, Otis
2015-01-01
We construct one-parameter families of solutions to the Einstein--Klein--Gordon equations bifurcating off the Kerr solution such that the underlying family of spacetimes are each an asymptotically flat, stationary, axisymmetric, black hole spacetime, and such that the corresponding scalar fields are non-zero and time-periodic. An immediate corollary is that for these Klein--Gordon masses, the Kerr family is not asymptotically stable as a solution to the Einstein--Klein--Gordon equations.
Time-periodic N\\'eel wall motions
Huber, Alexander
2010-01-01
In thin ferromagnetic films, the predominance of the magnetic shape anisotropy leads to in-plane magnetizations. The simplest domain wall in this geometry is the one-dimensional Neel wall that connects two magnetizations of opposite sign by a planar 180 degree rotation. In this paper, we perturb the static Neel wall profile in order to construct time-periodic Neel wall motions governed by to the Landau-Lifshitz-Gilbert equation. Our construction works within a certain parameter regime and requires the restriction to external magnetic fields with small amplitudes and suitable time averages.
Krylov-subspace acceleration of time periodic waveform relaxation
Energy Technology Data Exchange (ETDEWEB)
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.
Minimal model for short-time diffusion in periodic potentials.
Emary, Clive; Gernert, Robert; Klapp, Sabine H L
2012-12-01
We investigate the dynamics of a single, overdamped colloidal particle, which is driven by a constant force through a one-dimensional periodic potential. We focus on systems with large barrier heights where the lowest-order cumulants of the density field, that is, average position and the mean-squared displacement, show nontrivial (nondiffusive) short-time behavior characterized by the appearance of plateaus. We demonstrate that this "cage-like" dynamics can be well described by a discretized master equation model involving two states (related to two positions) within each potential valley. Nontrivial predictions of our approach include analytic expressions for the plateau heights and an estimate of the "de-caging time" obtained from the study of deviations from Gaussian behavior. The simplicity of our approach means that it offers a minimal model to describe the short-time behavior of systems with hindered dynamics.
Transient habitats limit development time for periodical cicadas.
Karban, Richard
2014-01-01
Periodical cicadas (Magicicada spp.) mature in 13 or 17 years, the longest development times for any non-diapausing insects. Selection may favor prolonged development since nymphs experience little mortality and individuals taking 17 years have been shown to have greater fecundity than those taking 13 years. Why don't periodical cicadas take even longer to develop? Nymphs feed on root xylem fluid and move little. Ovipositing females prefer fast-growing trees at forest edges. I hypothesized that (1) adults emerging at edges would be heavier than those from forest interiors and (2) habitat changes could limit development time. I collected newly eclosed females that had neither fed as adults nor moved from their site of development. For M. septendecim, females from edges were 4.9% heavier than those from the interior. I assumed that emergence density indicated habitat quality and measured density at eight sites in 1979, 1996, and 2013. Over three generations, variation in densities was great; densities at two sites crashed, and at one site they exploded to 579/m2 Habitat transience may limit development time because only adults can reassess habitats and reposition offspring. In conclusion, cicadas are affected by habitat characteristics, habitats change over 17 years, and cicadas may emerge, mate, and redistribute their offspring to track habitat dynamics.
Lagrangian structures in time-periodic vortical flows
Directory of Open Access Journals (Sweden)
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.
Almost Periodically Correlated Time Series in Business Fluctuations Analysis
Lenart, Lukasz
2012-01-01
We propose a non-standard subsampling procedure to make formal statistical inference about the business cycle, one of the most important unobserved feature characterising fluctuations of economic growth. We show that some characteristics of business cycle can be modelled in a non-parametric way by discrete spectrum of the Almost Periodically Correlated (APC) time series. On the basis of estimated characteristics of this spectrum business cycle is extracted by filtering. As an illustration we characterise the man properties of business cycles in industrial production index for Polish economy.
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.
Swimming and transport of bacteria in time-periodic flows
Winter, Rebecca; Patteson, Alison; Gagnon, David; Arratia, Paulo
The transport of bacteria can be highly influenced by external flows in oceans, rivers, and intestinal tracts. This has implications in biological systems for the performance of major biological processes, such as biofilm formation. In this study, we experimentally investigate the aggregation and transport of swimming Vibrio cholerae bacteria in time-periodic flows. Bacteria are placed in a well-characterized flow, and bacterial concentrations are recorded for a range of Reynolds numbers (Re) that spans two orders of magnitude, from 0.1 to 10. It is generally found that bacteria deplete from regions of high deformation rate and accumulate near vortices. This phenomenon seems to be dictated by a combination of bacterial activity and background flow vorticity. R.W. supported by NSF-GRFP.
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.
Navy Global Predictions for the Dynamo Time Period
Reynolds, C. A.; Ridout, J. A.; Flatau, M. K.; Chen, J.; Richman, J. G.; Jensen, T. G.; Shriver, J. F.
2014-12-01
The performance of 30-day simulations of the Navy Global Environmental Model (NAVGEM) is evaluated under several metrics. The time period of interest is the DYNAMO (Dynamics of Madden Julian Oscillation) field experiment period, starting late October 2011. The NAVGEM experiments are run at an effective 37-km resolution with several different SST configurations. The in the first set of experiments, the initial SST analysis, provided by the NCODA (Navy Coupled Ocean Data Assimilation) system, is either held fixed to the initial value (fixed SST) or updated every 6 hours. These forecasts are compared with forecasts in which the SST is updated with 3-h analyses from the Hybrid Coordinate Ocean Model (HYCOM), and forecasts in which NAVGEM is interactively coupled to HYCOM. Experiments are also performed with different physical parameterization options. The extended integrations are verified using observed OLR, TRMM precipitation estimates, and global analyses. The use of fixed SSTs is clearly sub-optimal. Biases in monthly mean fields are far more pronounced in the simulations where the SST is held fixed as compared to those in simulations where updated SST analyses are used. Biases in the monthly mean fields are further reduced when NAVGEM is coupled to HYCOM. Differences in SST can "migrate" to substantial changes in the time-mean land-surface temperatures, illustrating the substantial impact of SSTs over the full domain. Concerning the simulation of the MJO, some improvement is noted when the system is fully coupled, although the simulations still exhibit deficiencies such as eastward propagation that is too slow, and difficulty propagating over the maritime continent. Simulations that are started every 5 days indicate that the NAVGEM uncoupled system has difficulty predicting MJO initiation, but simulations started when the MJO is active in the Indian Ocean are able to capture eastward propagation characteristics. The coupled NAVGEM-HYCOM system shows ability to
Adaptive stabilization of discrete-time systems using linear periodically time varying controllers
Ortega, Romeo; Albertos, Pedro; Lozano, Rogelio
1988-01-01
A direct adaptive scheme based on the use of linear time-varying periodic controllers is proposed which estimates online the periodic coefficients of the controller. It is shown that adaptive stabilization is attained for all possibly nonstably invertible plants of known order but unknown delay. Although no appeal is made to persistency of excitation arguments, a provision is needed to avoid the singularity of an estimated matrix, this property being required only for the analysis and not the control calculations.
7 CFR 1.603 - How are time periods computed?
2010-01-01
... as follows: (1) The day of the act or event from which the period begins to run is not included. (2... delay in filing. (iii) The ALJ may grant the extension only if: (A) It would not unduly prejudice...
She, M.; Jiang, L. P.
2014-12-01
In this paper, an oscillating dark energy model is presented in an isotropic but inhomogeneous plane symmetric space-time by considering a time periodic varying deceleration parameter. We find three different types of new solutions which describe different scenarios of oscillating universe. The first two solutions show an oscillating universe with singularities. For the third one, the universe is singularity-free during the whole evolution. Moreover, the Hubble parameter oscillates and keeps positive which explores an interesting possibility to unify the early inflation and late time acceleration of the universe.
Zhao, Guangyu; Ruan, Shigui
2011-06-01
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 to its co-moving frame coordinate. We also show that the traveling wave solutions with wave speed c c(*).
Controlling mixing and segregation in time periodic granular flows
Bhattacharya, Tathagata
of realistic results and is used as a means of validating the model against available experimental data. The tuned model is then used to find the critical chute length for segregation based on the hypothesis that segregation can be thwarted if the particle flow is inverted at a rate above a critical forcing frequency. The critical frequency, fcrit, is inversely proportional to the characteristic time of segregation, ts. Mixing is observed instead of segregation when the chute length L screens or flotation methods. This approach is based on differences in the kinetic properties of the components of a mixture, such as the velocity of migration or diffusivity. In this portion of the work, two examples of novel rate-based separation devices are demonstrated. The first example involves the study of the dynamics of gravity-driven particles through an array of obstacles. Both discrete element (DEM) simulations and experiments are used to augment the understanding of this device. Dissipative collisions (both between the particles themselves and with the obstacles) give rise to a diffusive motion of particles perpendicular to the flow direction and the differences in diffusion lengths are exploited to separate the particles. The second example employs DEM to analyze a ratchet mechanism where a current of particles can be produced in a direction perpendicular to the energy input. In this setup, a vibrating saw-toothed base is employed to induce different mobility for different types of particles. The effect of operating conditions and design parameters on the separation efficiency are discussed. Keywords: granular flow, particle, mixing, segregation, discrete element method, particle dynamics, tumbler, chute, periodic flow inversion, collisional flow, rate-based separation, ratchet, static separator, dissipative particle dynamics, non-spherical droplet.
Institute of Scientific and Technical Information of China (English)
Jing HUI; Lan Sun CHEN
2004-01-01
The general system of differential equations describing predator-prey dynamics with impulsive effects is modified by the assumption that the coefficients are periodic functions of time. By use of standard techniques of bifurcation theory, it is known that this system has a positive periodic solution provided the time average of the predator's net uninhibited death rate is in a suitable range.The bifurcation is from the periodic solution of the time-dependent logistic equation for the prey (which results in the absence of predator).
Periodic Solutions of a Discrete Time Predator-Prey System
Institute of Scientific and Technical Information of China (English)
Yong-li Song; Mao-an Han
2006-01-01
In this paper, we discuss a discrete predator-prey system with a non-monotonic functional response,which models the dynamics of the prey and the predator having non-overlapping generations. By using the coincidence degree theory, sufficient conditions are obtained for the existence of positive periodic solutions.
Time Periodic Control of a Multi-Blade Helicopter.
1988-05-01
motion (13-22). Friedmann and Silverthorn (13) examined the flap-lag motion of a cantilevered rotor blade at arbitrary d, advance ratios. They concluded...Advance Ratio,* NASA SP-352: 25-34 (1974). 13. Friedmann, P. and L. J. Silverthorn . "Aeroelastic Stability of Periodic Systems with Applications to Rotor
Analysis of the Mode of the Periodically Time-varying Vibration Systems
Institute of Scientific and Technical Information of China (English)
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.
Time trends and periodic cycles in REM sleep eye movements.
Krynicki, V
1975-11-01
Eye movements during REM sleep episodes were tabulated in 16 young adults. REM episodes were then broken down into four ranges according to length in min: (1) 11.0-21.3; (2) 21.7-29.7; (3) 30.0-42.3; (4) 42.7 or longer. These data were then analyzed for linear and quadratic trends. Eight episodes had a significant linear trend, 10 had a significant quadratic trend, 7 had both linear and quadratic trends, while 12 had no trend. The residuals from the best-fitting polynomial curve were then subject to a spectral analysis. In addition, 2 long periods of pre-sleep wakefulness (approximately 2 h each) were also analyzed. In general, the spectral analysis revealed the dominant presence of a slow cycle (period of 10 min to about 30 min) the exact period of which varied according to the length of the REM episode. A binomial probability test indicated that the presence of slow cycles was significant in REM episodes except for those in the 21-30 min range. For the episodes of wakefulness, a dominant slow cycle was found in both cases. The results give the impression of similarity in the periodic organization of eye movements during REM sleep and waking. The data also indicated that an ultradian (70-150 min) cycle was present in eye movements during sleep and waking. Further, the finding of a decrease in eye movements before sleep onset, coupled with previous reports of an increase in eye movement after sleep onset, indicate the presence of a circadian cycle.
Transient aggregation and long-time diffusion of bacterial suspensions in time periodic flows
Qin, Boyang; Winter, Rebecca; Gurjar, Madhura; Gagnon, David; Patteson, Alison; Arratia, Paulo
2016-11-01
In this talk, the transport dynamics of swimming bacteria in time-periodic flows is investigated in experiments and simulations. Experiments are performed by introducing swimming bacteria (Vibrio cholerae) in a low Reynolds number, two-dimensional flow driven electromagnetically. We observe two distinct transport regimes: (i) entrapment of bacteria inside vortex and near elliptic points and (ii) aggregation and subsequent transport along the flow manifolds. These time-dependent behaviors are set by the interaction between swimmer kinematics (e.g. speed, tumbling frequency, etc) and flow properties. Numerical simulation using a stochastic Langevin model are able to capture the main experimental results including the entrapment of bacteria near elliptic points and the rapid spreading along manifolds. Results show a significant reduction in long-time effective diffusion of the swimmer as vortex strength is increased. The conditions for bacterial entrapment in vortex flows are discussed.
A Method for Determining Periods in Time Series.
1981-04-01
SUPPLEMENTARY NOTES IS. KEY WORDS (Conlinu an revere cide Ii necesry d Identify by block nmi 9ber) Univariate time series; spectral density function ; Newton’s...and the method is applied to a series of hormone levels data. KEY WORDS: Univariate time series; Spectral density function ; Newton’s Method...Z the set of integers, be a zero mean covariance stationary time series with autocovariance function R(v) = E(Y(t)Y(t+v)), vZ and spectral density function f
Delta T: Polynomial Approximation of Time Period 1620–2013
Directory of Open Access Journals (Sweden)
M. Khalid
2014-01-01
Full Text Available The difference between the Uniform Dynamical Time and Universal Time is referred to as ΔT (delta T. Delta T is used in numerous astronomical calculations, that is, eclipses,and length of day. It is additionally required to reduce quantified positions of minor planets to a uniform timescale for the purpose of orbital determination. Since Universal Time is established on the basis of the variable rotation of planet Earth, the quantity ΔT mirrors the unevenness of that rotation, and so it changes slowly, but rather irregularly, as time passes. We have worked on empirical formulae for estimating ΔT and have discovered a set of polynomials of the 4th order with nine intervals which is accurate within the range of ±0.6 seconds for the duration of years 1620–2013.
Time-Periodic Solution of a 2D Fourth-Order Nonlinear Parabolic Equation
Indian Academy of Sciences (India)
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.
Time-periodic Solution to a Nonlinear Parabolic Type Equation of Higher Order
Institute of Scientific and Technical Information of China (English)
Yan-ping Wang; You-lin Zhang
2008-01-01
In this paper, the existence and uniqueness of time-periodic generalized solutions and time-periodic classical solutions to a class of parabolic type equation of higher order are proved by Gaierkin method.
EXISTENCE OF TIME PERIODIC SOLUTIONS FOR A DAMPED GENERALIZED COUPLED NONLINEAR WAVE EQUATIONS
Institute of Scientific and Technical Information of China (English)
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.
Compact attractors for time-periodic age-structured population models
Directory of Open Access Journals (Sweden)
Pierre Magal
2001-10-01
Full Text Available In this paper we investigate the existence of compact attractors for time-periodic age-structured models. So doing we investigate the eventual compactness of a class of abstract non-autonomous semiflow (non necessarily periodic. We apply this result to non-autonomous age-structured models. In the time periodic case, we obtain the existence of a periodic family of compact subsets that is invariant by the semiflow, and attract the solutions of the system.
Linear Impulsive Periodic System with Time-Varying Generating Operators on Banach Space
Directory of Open Access Journals (Sweden)
Wei W
2007-01-01
Full Text Available A class of the linear impulsive periodic system with time-varying generating operators on Banach space is considered. By constructing the impulsive evolution operator, the existence of -periodic -mild solution for homogeneous linear impulsive periodic system with time-varying generating operators is reduced to the existence of fixed point for a suitable operator. Further the alternative results on -periodic -mild solution for nonhomogeneous linear impulsive periodic system with time-varying generating operators are established and the relationship between the boundness of solution and the existence of -periodic -mild solution is shown. The impulsive periodic motion controllers that are robust to parameter drift are designed for a given periodic motion. An example given for demonstration.
Time-periodic solutions of the Einstein’s field equations II:geometric singularities
Institute of Scientific and Technical Information of China (English)
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.
Time-periodic solutions of the Einstein’s field equations Ⅰ:general framework
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In this paper,we develop a new algorithm to find the exact solutions of the Einstein’s field equations.Time-periodic solutions are constructed by using the new algorithm.The singularities of the time-periodic solutions are investigated and some new physical phenomena,such as degenerate event horizon and time-periodic event horizon,are found.The applications of these solutions in modern cosmology and general relativity are expected.
EXISTENCE OF PERIODIC SOLUTIONS FOR A DISCRETE-TIME MODEL OF TWO-CELL CNNS
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
We investigate a class of discrete-time model of two-cell cellular neural networks with symmetric template. By using the Lyapunov direct method, La-Salle's invariance principle, we discuss the existence and the stability of periodic solutions. The model considered has attractive 2-periodic and unstable 2-periodic solutions.
Time-variation of the near 5-month period of sunspot numbers
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The variation of the near 5-month period of sunspot numbers is discussed on the basis of the wavelet transform of the daily sunspot number series in the 14th-22nd solar cycles. The result shows that the period exists in every cycle and its energy density (amplitude) is comparatively large in the peak section of the cycle. In the distinct cycle, the length and intensity of the period is different, which means that the period varies with time. The near 25-day period is also analyzed and it is found to be time- variable and even not very stable in the peak section of the cycle. The variations of the two periods show that the near 5-month period should not be simply regarded as the multiples of the near 25-day period.
Adjoint Sensitivities of Time-Periodic Nonlinear Structural Dynamics via Model Reduction
2009-10-01
AFRL-RB-WP-TR-2009-3241 ADJOINT SENSITIVITIES OF TIME-PERIODIC NONLINEAR STRUCTURAL DYNAMICS VIA MODEL REDUCTION Bret Stanford, Philip...SENSITIVITIES OF TIME-PERIODIC NONLINEAR STRUCTURAL DYNAMICS VIA MODEL REDUCTION 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT... structural dynamics problems 1 , which require the solution of a system of equations many times within each time step for a nonlinear system (to
Unique Existence Theorem of Solution of Almost Periodic Differential Equations on Time Scales
Directory of Open Access Journals (Sweden)
Meng Hu
2012-01-01
Full Text Available By using the theory of calculus on time scales and M-matrix theory, the unique existence theorem of solution of almost periodic differential equations on almost periodic time scales is established. The result can be used to a large of dynamic systems.
Unique Existence Theorem of Solution of Almost Periodic Differential Equations on Time Scales
Meng Hu; Lili Wang
2012-01-01
By using the theory of calculus on time scales and M-matrix theory, the unique existence theorem of solution of almost periodic differential equations on almost periodic time scales is established. The result can be used to a large of dynamic systems.
Analytical Solutions of Time Periodic Electroosmotic Flow in a Semicircular Microchannel
Directory of Open Access Journals (Sweden)
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.
Korotkov, E. V.; Korotkova, M. A.
2017-01-01
The purpose of this study was to detect latent periodicity in the presence of deletions or insertions in the analyzed data, when the points of deletions or insertions are unknown. A mathematical method was developed to search for periodicity in the numerical series, using dynamic programming and random matrices. The developed method was applied to search for periodicity in the Euro/Dollar (Eu/) exchange rate, since 2001. The presence of periodicity within the period length equal to 24 h in the analyzed financial series was shown. Periodicity can be detected only with insertions and deletions. The results of this study show that periodicity phase shifts, depend on the observation time. The reasons for the existence of the periodicity in the financial ranks are discussed.
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
Institute of Scientific and Technical Information of China (English)
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.
Energy Technology Data Exchange (ETDEWEB)
Huang Zhenkun [Department of Mathematics, School of Sciences, Zhejiang University, Hangzhou, Zhejiang 310027 (China) and School of Sciences, Jimei University, Xiamen, Fujian 361021 (China)]. E-mail: huangdoc@tom.com; Wang Xinghua [Department of Mathematics, School of Sciences, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Gao Feng [School of Sciences, Jimei University, Xiamen, Fujian 361021 (China)
2006-02-06
In this Letter, we discuss discrete-time analogue of a continuous-time cellular neural network. Sufficient conditions are obtained for the existence of a unique almost periodic sequence solution which is globally attractive. Our results demonstrate dynamics of the formulated discrete-time analogue as mathematical models for the continuous-time cellular neural network in almost periodic case. Finally, a computer simulation illustrates the suitability of our discrete-time analogue as numerical algorithms in simulating the continuous-time cellular neural network conveniently.
Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor-Blade Systems
DEFF Research Database (Denmark)
Christensen, Rene Hardam; Santos, Ilmar
2003-01-01
to be 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...... of active modal controllers. The main aim is to reduce vibrations in periodic time-varying structures. Special emphasis is given to vibration control of coupled bladed rotor systems. A state feedback modal control law is developed based on modal analysis in periodic time-varying structures. The first step...... is reformulated using complex mode theory. Next, a linear constant gain controller for the reformulated system is designed by linear control technique. Finally, this constant gain controller is transformed to a time-periodic form by applying reverse modal transformation. The non-measurable states are estimated...
Modal Vibration Control in Periodic Time-Varying Structures with Focus on Rotor Blade Systems
DEFF Research Database (Denmark)
Christensen, Rene Hardam; Santos, Ilmar
2004-01-01
to be 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...... of active modal controllers. The main aim is to reduce vibrations in periodic time-varying structures. Special emphasis is given to vibration control of coupled bladed rotor systems. A state feedback modal control law is developed based on modal analysis in periodic time-varying structures. The first step...... is reformulated using complex mode theory. Next, a linear constant gain controller for the reformulated system is designed by linear control technique. Finally, this constant gain controller is transformed to a time-periodic form by applying reverse modal transformation. The non-measurable states are estimated...
Stability and robustness analysis of a linear time-periodic system subjected to random perturbations
Redkar, Sangram; Liu, J.; Sinha, S. C.
2012-03-01
In this work, new methods of guaranteeing the stability of linear time periodic dynamical systems with stochastic perturbations are presented. In the approaches presented here, the Lyapunov-Floquet (L-F) transformation is applied first so that the linear time-periodic part of the equations becomes time-invariant. For the linear time periodic system with stochastic perturbations, a stability theorem and related corollary have been suggested using the results previously obtained by Infante. This technique is not only applicable to systems with stochastic parameters but also to systems with deterministic variation in parameters. Some illustrative examples are presented to show the practical applications. These methods can be used to investigate the degree of robustness and design controllers for systems with time periodic coefficients subjected to random perturbations.
DEFF Research Database (Denmark)
Simonsen, Poul Erik; Niemann, L.; Meyrowitsch, Dan Wolf
1997-01-01
pattern was observed. Mathematical analysis of the data indicated a peak at 0152 h and a periodicity index of 117.5. A periodicity equation was developed describing the average relation between mf intensity and hour of the day for the study area. Based on the observed periodicity pattern, the effect...... of blood sampling before peak time is discussed, and the importance of taking sampling time into consideration when analysing data from epidemiological studies is emphasized. A simple method is devised which can be used to adjust for the influence of time on mf intensities, in studies where accurate...
Existence of Almost-Periodic Solutions for Lotka-Volterra Cooperative Systems with Time Delay
Directory of Open Access Journals (Sweden)
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.
Period, epoch and prediction errors of ephemeris from continuous sets of timing measurements
Deeg, Hans J
2015-01-01
Space missions such as Kepler and CoRoT have led to large numbers of eclipse or transit measurements in nearly continuous time series. This paper shows how to obtain the period error in such measurements from a basic linear least-squares fit, and how to correctly derive the timing error in the prediction of future transit or eclipse events. Assuming strict periodicity, a formula for the period error of such time series is derived: sigma_P = sigma_T (12/( N^3-N))^0.5, where sigma_P is the period error; sigma_T the timing error of a single measurement and N the number of measurements. Relative to the iterative method for period error estimation by Mighell & Plavchan (2013), this much simpler formula leads to smaller period errors, whose correctness has been verified through simulations. For the prediction of times of future periodic events, the usual linear ephemeris where epoch errors are quoted for the first time measurement, are prone to overestimation of the error of that prediction. This may be avoided...
Time courses of myofascial temporomandibular disorder complaints during a 12-month follow-up period
M.K.A. van Selms; F. Lobbezoo; M. Naeije
2009-01-01
AIMS: To investigate the time courses of myofascial temporomandibular disorder (TMD) pain and mandibular function impairment (MFI), and to identify predictive factors associated with these time courses. METHODS: During a 12-month period following conservative TMD treatment, the time courses of myofa
Periodicity in a "Food-limited" Population Model with Toxicants and Time Delays
Institute of Scientific and Technical Information of China (English)
Meng Fan; Ke Wang
2002-01-01
With the help of a continuation theorem based on Gaines and Mawhin's coincidence degree, we study the global existence of positive periodic solutions of a "food-limited" population model with toxicants and time delays. Some new results are obtained.
Positive Almost Periodic Solutions for a Time-Varying Fishing Model with Delay
Directory of Open Access Journals (Sweden)
Xia Li
2011-01-01
Full Text Available This paper is concerned with a time-varying fishing model with delay. By means of the continuation theorem of coincidence degree theory, we prove that it has at least one positive almost periodic solution.
Bayesian detection of periodic mRNA time profiles without use of training examples
Directory of Open Access Journals (Sweden)
Gustafsson Mats G
2006-02-01
Full Text Available Abstract Background Detection of periodically expressed genes from microarray data without use of known periodic and non-periodic training examples is an important problem, e.g. for identifying genes regulated by the cell-cycle in poorly characterised organisms. Commonly the investigator is only interested in genes expressed at a particular frequency that characterizes the process under study but this frequency is seldom exactly known. Previously proposed detector designs require access to labelled training examples and do not allow systematic incorporation of diffuse prior knowledge available about the period time. Results A learning-free Bayesian detector that does not rely on labelled training examples and allows incorporation of prior knowledge about the period time is introduced. It is shown to outperform two recently proposed alternative learning-free detectors on simulated data generated with models that are different from the one used for detector design. Results from applying the detector to mRNA expression time profiles from S. cerevisiae showsthat the genes detected as periodically expressed only contain a small fraction of the cell-cycle genes inferred from mutant phenotype. For example, when the probability of false alarm was equal to 7%, only 12% of the cell-cycle genes were detected. The genes detected as periodically expressed were found to have a statistically significant overrepresentation of known cell-cycle regulated sequence motifs. One known sequence motif and 18 putative motifs, previously not associated with periodic expression, were also over represented. Conclusion In comparison with recently proposed alternative learning-free detectors for periodic gene expression, Bayesian inference allows systematic incorporation of diffuse a priori knowledge about, e.g. the period time. This results in relative performance improvements due to increased robustness against errors in the underlying assumptions. Results from applying
Interfacial instability in a time-periodic rotating Hele-Shaw Cell
Directory of Open Access Journals (Sweden)
Bouchgl J.
2014-01-01
Full Text Available The effect of time-periodic angular velocity on the interfacial instability of two immiscible, viscous fluids of different densities and confined in an annular Hele-Shaw cell is investigated. An inviscid linear stability analysis of the viscous and time dependent basic flow leads to a periodic Mathieu oscillator describing the evolution of the interfacial amplitude. We show that the relevant parameters that control the interface are the Bond number, viscosity ratio, Atwood number and the frequency number.
Time perspective of the convicts of acquisitive crime in the initial period of serving the sentence
Directory of Open Access Journals (Sweden)
A. A. Martynova
2014-01-01
Full Text Available There were no statistically significant differences in the initial period of serving the sentence by all parameters of time perspective regardless of gender and the number of the previous records of acquisitive crime. A phenomenon of «perceptual distortion of course of life in the time continuum» was revealed. The degree of its manifestation affects the success of adaptation in the initial period of serving the sentence.
DETERMINATION OF THE PERIOD OF A TORSION PENDULUM BY THE FITTING METHOD IN REAL TIME
Institute of Scientific and Technical Information of China (English)
无
1998-01-01
A phenomenological study on the fitting method in real time has been done, and the method was applied to process and analyze the extensive data of a long period torsion pendulum used to determine Newtonian gravitational constant G. The result shows that the fitting method in real time is effective to determine the period of a torsion pendulum with a relative precision of 10-5 orders.
Some recent results on Schrödinger equations with time-periodic potentials
DEFF Research Database (Denmark)
Galtbayar, A.; Jensen, Arne; Yajima, K.
2004-01-01
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....
Dynamical systems analysis of fluid transport in time-periodic vortex ring flows
Shariff, Karim; Leonard, Anthony; Ferziger, Joel H.
2006-01-01
It is known that the stable and unstable manifolds of dynamical systems theory provide a powerful tool for understanding Lagrangian aspects of time-periodic flows. In this work we consider two time-periodic vortex ring flows. The first is a vortex ring with an elliptical core. The manifolds provide information about entrainment and detrainment of irrotational fluid into and out of the volume transported with the ring. The likeness of the manifolds with features observed in flow visualization ...
Stability and periodicity of solutions for delay dynamic systems on time scales
Directory of Open Access Journals (Sweden)
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
Energy Technology Data Exchange (ETDEWEB)
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.
DEFF Research Database (Denmark)
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...
DEFF Research Database (Denmark)
Azhar, Hussain
This study looks at polarization and its components’ sensitivity to assumptions about equivalence scales, income definition, ethical income distribution parameters, and the income accounting period. A representative sample of Danish individual incomes from 1984 to 2002 is utilised. Results show...... that polarization has increased over time, regardless of the applied measure, when the last part of the period is compared to the first part of the period. Primary causes being increased inequality (alienation) and faster income growth among high incomes relative to those in the middle of the distribution....... Increasing the accounting period confirms the reduction in inequality found for shorter periods, but polarization is virtually unchanged, because income group identification increases. Applying different equivalence scales does not change polarization ranking for different years, but identification ranks...
Almost Periodic Solution for Memristive Neural Networks with Time-Varying Delays
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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.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In this paper, global exponential stability of almost periodic solution of cellular neural networks with time-varing delays (CNNVDs) is considered. By using the methods of the topological degree theory and generalized Halanay inequality, a few new applicable criteria are established for the existence and global exponential stability of almost periodic solution. Some previous results are improved and extended in this letter and one example is given to illustrate the effectiveness of the new results.
Dynamics of Periodic Waves in Bose-Einstein Condensate with Time-Dependent Atomic Scattering Length
Institute of Scientific and Technical Information of China (English)
LI Hua-Mei
2007-01-01
Evolution of periodic waves and solitary waves in Bose-Einstein condensates (BECs) with time-dependent atomic scattering length in an expulsive parabolic potential is studied. Based on the mapping deformation method, we successfully obtain periodic wave solutions and solitary wave solutions, including the bright and dark soliton solutions. The results in this paper include some in the literatures [Plys. Rev. Lett. 94 (2005) 050402 and Chin. Phys. Lett. 22(2005) 1855].
Rank One Strange Attractors in Periodically Kicked Predator-Prey System with Time-Delay
Yang, Wenjie; Lin, Yiping; Dai, Yunxian; Zhao, Huitao
2016-06-01
This paper is devoted to the study of the problem of rank one strange attractor in a periodically kicked predator-prey system with time-delay. Our discussion is based on the theory of rank one maps formulated by Wang and Young. Firstly, we develop the rank one chaotic theory to delayed systems. It is shown that strange attractors occur when the delayed system undergoes a Hopf bifurcation and encounters an external periodic force. Then we use the theory to the periodically kicked predator-prey system with delay, deriving the conditions for Hopf bifurcation and rank one chaos along with the results of numerical simulations.
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
Dynamics and Complexity in a Time Delay Model of RNA Silencing with Periodic Forcing
Directory of Open Access Journals (Sweden)
Svetoslav Nikolov
2008-10-01
Full Text Available Simple periodic behavior and occurrence of complex oscillatory phenomena underlie of a large number of biochemical system models. In many cases the transition from stable to simple/complex oscillatory behavior can be connected with the appearance of abnormal process likes as cancer. In this paper we propose a time delay model of RNA silencing (also known as RNA interference with periodic forcing. In organisms with RNA silencing, each cell has a miniature "immune system" able to generate and amplify specific responses to a variety of gene transcripts. The consequences of a time delay on the dynamics of this model are analysed using Hopf's theorem. Our analytical calculations predict that time delay acts as a key bifurcation parameter. From the accomplished numerical results, it becomes clear that model has complexity oscillatory behavior when the amplitude of periodic force (i.e. the confusion in the target mRNA synthesis is large.
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.
Environmental input and cognitive growth: a study using time-period comparisons.
Huttenlocher, J; Levine, S; Vevea, J
1998-08-01
In this study, we examined the relation of input to cognitive growth in a single population of children. We studied 4 domains: Language, Spatial Operations, Concepts, and Associative Memory. Four groups of children drawn from the same population were tested in October of kindergarten, April of kindergarten, October of first grade, and April of first grade. These time points are 6 months apart, but they span periods that differ in amount of school input children receive. Much greater growth was found over time periods with greater amounts of school input (October to April) than over time periods with less school input (April to October) for Language, Spatial Operations, and Concepts, but not for Associative Memory. These findings suggest that amount of input is causally related to cognitive growth in particular domains.
A Time-Delayed Mathematical Model for Tumor Growth with the Effect of a Periodic Therapy
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Shihe Xu
2016-01-01
Full Text Available 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.
Exact Feasibility Tests for Real-Time Scheduling of Periodic Tasks upon Multiprocessor Platforms
Cucu, Liliana
2008-01-01
In this paper we study the global scheduling of periodic task systems upon multiprocessor platforms. We first show two very general properties which are well-known for uniprocessor platforms and which remain for multiprocessor platforms: (i) under few and not so restrictive assumptions, we show that feasible schedules of periodic task systems are periodic from some point with a period equal to the least common multiple of task periods and (ii) for the specific case of synchronous periodic task systems, we show that feasible schedules repeat from the origin. We then present our main result: we characterize, for task-level fixed-priority schedulers and for asynchronous constrained or arbitrary deadline periodic task models, upper bounds of the first time instant where the schedule repeats. We show that job-level fixed-priority schedulers are predictable upon unrelated multiprocessor platforms. For task-level fixed-priority schedulers, based on the upper bounds and the predictability property, we provide for asy...
Ways of spending free time by alcohol addicts during periods of drinking and rehabilitation
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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
Energy Technology Data Exchange (ETDEWEB)
Skolski, J. Z. P., E-mail: j.z.p.skolski@utwente.nl; Vincenc Obona, J. [Materials innovation institute M2i, Faculty of Engineering Technology, Chair of Applied Laser Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Römer, G. R. B. E.; Huis in ' t Veld, A. J. [Faculty of Engineering Technology, Chair of Applied Laser Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)
2014-03-14
A model predicting the formation of laser-induced periodic surface structures (LIPSSs) is presented. That is, the finite-difference time domain method is used to study the interaction of electromagnetic fields with rough surfaces. In this approach, the rough surface is modified by “ablation after each laser pulse,” according to the absorbed energy profile, in order to account for inter-pulse feedback mechanisms. LIPSSs with a periodicity significantly smaller than the laser wavelength are found to “grow” either parallel or orthogonal to the laser polarization. The change in orientation and periodicity follow from the model. LIPSSs with a periodicity larger than the wavelength of the laser radiation and complex superimposed LIPSS patterns are also predicted by the model.
Skolski, J. Z. P.; Römer, G. R. B. E.; Vincenc Obona, J.; Huis in't Veld, A. J.
2014-03-01
A model predicting the formation of laser-induced periodic surface structures (LIPSSs) is presented. That is, the finite-difference time domain method is used to study the interaction of electromagnetic fields with rough surfaces. In this approach, the rough surface is modified by "ablation after each laser pulse," according to the absorbed energy profile, in order to account for inter-pulse feedback mechanisms. LIPSSs with a periodicity significantly smaller than the laser wavelength are found to "grow" either parallel or orthogonal to the laser polarization. The change in orientation and periodicity follow from the model. LIPSSs with a periodicity larger than the wavelength of the laser radiation and complex superimposed LIPSS patterns are also predicted by the model.
2T-PERIODIC SOLUTION FOR m ORDER NEUTRAL TYPE DIFFERENTIAL EQUATIONS WITH TIME DELAYS
Institute of Scientific and Technical Information of China (English)
张保生; 朱光辉
2002-01-01
Periodic solution of m order linear neutral equations with constant coefficient and time delays was studied. Existence and uniqueness of 2 T-periodic solutions for the equation were discussed by using the method of Fourier series. Some new necessary and sufficient conditions of existence and uniqueness of 2 T-periodic solutions for the equation are obtained. The main result is used widely. It contains results in some correlation paper for its special case, improves and extends the main results in them. Existence of periodic solution for the equation in larger number of particular case can be checked by using the result, but cannot be checked in another paper. In other words, the main result in this paper is most generalized for (1), the better result cannot be found by using the same method.
A Simple Discrete Model of Brownian Motors: Time-periodic Markov Chains
Ge, Hao; Jiang, Da-Quan; Qian, Min
2006-05-01
In this paper, we consider periodically inhomogeneous Markov chains, which can be regarded as a simple version of physical model—Brownian motors. We introduce for them the concepts of periodical reversibility, detailed balance, entropy production rate and circulation distribution. We prove the equivalence of the following statements: The time-periodic Markov chain is periodically reversible; It is in detailed balance; Kolmogorov's cycle condition is satisfied; Its entropy production rate vanishes; Every circuit and its reversed circuit have the same circulation weight. Hence, in our model of Markov chains, the directed transport phenomenon of Brownian motors, i.e. the existence of net circulation, can occur only in nonequilibrium and irreversible systems. Moreover, we verify the large deviation property and the Gallavotti-Cohen fluctuation theorem of sample entropy production rates of the Markov chain.
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.
Kafka, K. R. P.; D. R. Austin; Li, H.; Yi, A; Cheng, J.; Chowdhury, E. A.
2015-01-01
Time-resolved diffraction microscopy technique has been used to observe the formation of laser-induced periodic surface structures (LIPSS) from the interaction of a single femtosecond laser pulse (pump) with a nano-scale groove mechanically formed on a single-crystal Cu substrate. The interaction dynamics (0-1200 ps) was captured by diffracting a time-delayed, frequency-doubled pulse from nascent LIPSS formation induced by the pump with an infinity-conjugate microscopy setup. The LIPSS ripple...
Molecular response properties from a Hermitian eigenvalue equation for a time-periodic Hamiltonian.
Pawłowski, Filip; Olsen, Jeppe; Jørgensen, Poul
2015-03-21
The time-dependent Schrödinger equation for a time-periodic perturbation is recasted into a Hermitian eigenvalue equation, where the quasi-energy is an eigenvalue and the time-periodic regular wave function an eigenstate. From this Hermitian eigenvalue equation, a rigorous and transparent formulation of response function theory is developed where (i) molecular properties are defined as derivatives of the quasi-energy with respect to perturbation strengths, (ii) the quasi-energy can be determined from the time-periodic regular wave function using a variational principle or via projection, and (iii) the parametrization of the unperturbed state can differ from the parametrization of the time evolution of this state. This development brings the definition of molecular properties and their determination on par for static and time-periodic perturbations and removes inaccuracies and inconsistencies of previous response function theory formulations. The development where the parametrization of the unperturbed state and its time evolution may differ also extends the range of the wave function models for which response functions can be determined. The simplicity and universality of the presented formulation is illustrated by applying it to the configuration interaction (CI) and the coupled cluster (CC) wave function models and by introducing a new model-the coupled cluster configuration interaction (CC-CI) model-where a coupled cluster exponential parametrization is used for the unperturbed state and a linear parametrization for its time evolution. For static perturbations, the CC-CI response functions are shown to be the analytical analogues of the static molecular properties obtained from finite field equation-of-motion coupled cluster (EOMCC) energy calculations. The structural similarities and differences between the CI, CC, and CC-CI response functions are also discussed with emphasis on linear versus non-linear parametrizations and the size-extensivity of the obtained
Well-Posedness and averaging of NLS with time-periodic dispersion management
Antonelli, Paolo; Sparber, Christof
2012-01-01
We consider the Cauchy problem for dispersion managed nonlinear Schroedinger equations, where the dispersion map is assumed to be periodic and piecewise constant in time. We establish local and global well-posedness results and the possibility of finite time blow-up. In addition, we shall study the scaling limit of fast dispersion management and establish convergence to an effective model with averaged dispersion.
Directory of Open Access Journals (Sweden)
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.
Periodic Solution to BAM-type Cohen-Grossberg Neural Network with Time-varying Delays
Institute of Scientific and Technical Information of China (English)
An-ping Chen; Qun-hua Gu
2011-01-01
By using the continuation theorem of Mawhin's coincidence degree theory and the Liapunov functional method, some sufficient conditions are obtained to ensure the existence, uniqueness and the global exponential stability of the periodic solution to the BAM-type Cohen-Grossberg neural networks involving time-varying delays.
Directory of Open Access Journals (Sweden)
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.
Mapping the dynamics of adverse drug reactions in subsequent time periods using INDSCAL
Rikken, F.; Kiers, H.A.L.; Vos, R.
1995-01-01
In this study we have focused on the problem of mapping the dynamics of co-word-matrices from subsequent time periods. Methods for mapping dynamics are important for following trends in research. We have explored the possibilities of a three way multidimensional scaling method, INDSCAL. We are espec
Global stabilization of linear periodically time-varying switched systems via matrix inequalities
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
In this paper, we address the stabilization problem for linear periodically time-varying switched systems.Using discretization technique, we derive new conditions for the global stabilizability in terms of the solution of matrix inequalities. An algorithm for finding stabilizing controller and switching strategy is presented.
Institute of Scientific and Technical Information of China (English)
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.
Periodic Solutions for a Class of Singular Hamiltonian Systems on Time Scales
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Xiaofang Meng
2014-01-01
Full Text Available We are concerned with a class of singular Hamiltonian systems on time scales. Some results on the existence of periodic solutions are obtained for the system under consideration by means of the variational methods and the critical point theory.
Almost periodic solution of shunting inhibitory cellular neural networks with time-varying delay
Energy Technology Data Exchange (ETDEWEB)
Huang Xia; Cao Jinde
2003-07-28
Several sufficient conditions are obtained for the existence of almost periodic solution and its attractivity of shunting inhibitory cellular neural networks with time-varying delay based on the fixed point method and Halanay inequality technique. Some previous results are improved and extended in this Letter and two examples are given to illustrate the effectiveness of the new results.
Almost Periodic Solutions to Dynamic Equations on Time Scales and Applications
Directory of Open Access Journals (Sweden)
Yongkun Li
2012-01-01
equations on time scales. Then, as an application, using these concepts and results, we establish sufficient conditions for the existence and exponential stability of almost periodic solution to a class of Hopfield neural networks with delays. Finally, two examples and numerical simulations given to illustrate our results are plausible and meaningful.
THE VARYING LIGHT CURVE AND TIMINGS OF THE ULTRASHORT-PERIOD CONTACT BINARY KIC 9532219
Energy Technology Data Exchange (ETDEWEB)
Lee, Jae Woo; Hong, Kyeongsoo; Koo, Jae-Rim; Park, Jang-Ho, E-mail: jwlee@kasi.re.kr, E-mail: kshong@kasi.re.kr, E-mail: koojr@kasi.re.kr, E-mail: pooh107162@kasi.re.kr [Korea Astronomy and Space Science Institute, Daejeon 34055 (Korea, Republic of)
2016-03-20
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 T{sub 1}–T{sub 2} = 172 K, and a third light of l{sub 3} = 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{sub ⊙} 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.
Estimating Periodic Software Rejuvenation Schedules under Discrete-Time Operation Circumstance
Iwamoto, Kazuki; Dohi, Tadashi; Kaio, Naoto
Software rejuvenation is a preventive and proactive solution that is particularly useful for counteracting the phenomenon of software aging. In this article, we consider periodic software rejuvenation models based on the expected cost per unit time in the steady state under discrete-time operation circumstance. By applying the discrete renewal reward processes, we describe the stochastic behavior of a telecommunication billing application with a degradation mode, and determine the optimal periodic software rejuvenation schedule minimizing the expected cost. Similar to the earlier work by the same authors, we develop a statistically non-parametric algorithm to estimate the optimal software rejuvenation schedule, by applying the discrete total time on test concept. Numerical examples are presented to estimate the optimal software rejuvenation schedules from the simulation data. We discuss the asymptotic behavior of estimators developed in this paper.
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
Energy Technology Data Exchange (ETDEWEB)
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.
Directory of Open Access Journals (Sweden)
J. Rodrigues Dias
2006-11-01
Full Text Available Systems with different lifetime distributions, associated with increasing, decreasing, constant, and bathtub-shaped hazard rates, are examined in this paper. It is assumed that a failure is only detected if systems are inspected. New approximate solutions for the inspection period and for the expected duration of hidden faults are presented, on the basis of the assumption that only periodic and perfect inspections are carried out. By minimizing total expected cost per unit of time, on the basis of numerical results and a range of comparisons, the conclusion is drawn that these new approximate solutions are extremely useful and simple to put into practice.
Hu, Jin; Wang, Jun
2015-06-01
In recent years, complex-valued recurrent neural networks have been developed and analysed in-depth in view of that they have good modelling performance for some applications involving complex-valued elements. In implementing continuous-time dynamical systems for simulation or computational purposes, it is quite necessary to utilize a discrete-time model which is an analogue of the continuous-time system. In this paper, we analyse a discrete-time complex-valued recurrent neural network model and obtain the sufficient conditions on its global exponential periodicity and exponential stability. Simulation results of several numerical examples are delineated to illustrate the theoretical results and an application on associative memory is also given.
Complete Periodic Synchronization of Memristor-Based Neural Networks with Time-Varying Delays
Directory of Open Access Journals (Sweden)
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.
Weijtjens, Wout; Lataire, John; Devriendt, Christof; Guillaume, Patrick
2014-12-01
Periodical loads, such as waves and rotating machinery, form a problem for operational modal analysis (OMA). In OMA only the vibrations of a structure of interest are measured and little to nothing is known about the loads causing these vibrations. Therefore, it is often assumed that all dynamics in the measured data are linked to the system of interest. Periodical loads defy this assumption as their periodical behavior is often visible within the measured vibrations. As a consequence most OMA techniques falsely associate the dynamics of the periodical load with the system of interest. Without additional information about the load, one is not able to correctly differentiate between structural dynamics and the dynamics of the load. In several applications, e.g. turbines and helicopters, it was observed that because of periodical loads one was unable to correctly identify one or multiple modes. Transmissibility based OMA (TOMA) is a completely different approach to OMA. By using transmissibility functions to estimate the structural dynamics of the system of interest, all influence of the load-spectrum can be eliminated. TOMA therefore allows to identify the modal parameters without being influenced by the presence of periodical loads, such as harmonics. One of the difficulties of TOMA is that the analyst is required to find two independent datasets, each associated with a different loading condition of the system of interest. This poses a dilemma for TOMA; how can an analyst identify two different loading conditions when little is known about the loads on the system? This paper tackles that problem by assuming that the loading conditions vary continuously over time, e.g. the changing wind directions. From this assumption TOMA is developed into a time-varying framework. This development allows TOMA to not only cope with the continuously changing loading conditions. The time-varying framework also enables the identification of the modal parameters from a single dataset
Moeeni, Hamid; Bonakdari, Hossein; Fatemi, Seyed Ehsan
2017-04-01
Because time series stationarization has a key role in stochastic modeling results, three methods are analyzed in this study. The methods are seasonal differencing, seasonal standardization and spectral analysis to eliminate the periodic effect on time series stationarity. First, six time series including 4 streamflow series and 2 water temperature series are stationarized. The stochastic term for these series obtained with ARIMA is subsequently modeled. For the analysis, 9228 models are introduced. It is observed that seasonal standardization and spectral analysis eliminate the periodic term completely, while seasonal differencing maintains seasonal correlation structures. The obtained results indicate that all three methods present acceptable performance overall. However, model accuracy in monthly streamflow prediction is higher with seasonal differencing than with the other two methods. Another advantage of seasonal differencing over the other methods is that the monthly streamflow is never estimated as negative. Standardization is the best method for predicting monthly water temperature although it is quite similar to seasonal differencing, while spectral analysis performed the weakest in all cases. It is concluded that for each monthly seasonal series, seasonal differencing is the best stationarization method in terms of periodic effect elimination. Moreover, the monthly water temperature is predicted with more accuracy than monthly streamflow. The criteria of the average stochastic term divided by the amplitude of the periodic term obtained for monthly streamflow and monthly water temperature were 0.19 and 0.30, 0.21 and 0.13, and 0.07 and 0.04 respectively. As a result, the periodic term is more dominant than the stochastic term for water temperature in the monthly water temperature series compared to streamflow series.
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.
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 ...
Energy Technology Data Exchange (ETDEWEB)
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.
An EOQ Model for Phase Inventory with Induced Demand and Periodic Cycle Time
Directory of Open Access Journals (Sweden)
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.
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
2015-08-21
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.
Application of predictive control scheduling method to real-time periodic control tasks overrun
Institute of Scientific and Technical Information of China (English)
SHEN Qing; GUI Wei-hua; YANG Chun-hua; YANG Tie-jun
2007-01-01
Based on the abort strategy of fixed periods, a novel predictive control scheduling methodology was proposed to efficiently solve overrun problems. By applying the latest control value in the prediction sequences to the control objective, the new strategy was expected to optimize the control system for better performance and yet guarantee the schedulability of all tasks under overrun. The schedulability of the real-time systems with p-period overruns was analyzed, and the corresponding stability criteria was given as well. The simulation results show that the new approach can improve the performance of control system compared to that of conventional abort strategy, it can reduce the overshoot and adjust time as well as ensure the schedulability and stability.
Directory of Open Access Journals (Sweden)
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.
Time functions of deep earthquakes from broadband and short-period stacks
Houston, H.; Benz, H.M.; Vidale, J.E.
1998-01-01
To constrain dynamic source properties of deep earthquakes, we have systematically constructed broadband time functions of deep earthquakes by stacking and scaling teleseismic P waves from U.S. National Seismic Network, TERRAscope, and Berkeley Digital Seismic Network broadband stations. We examined 42 earthquakes with depths from 100 to 660 km that occurred between July 1, 1992 and July 31, 1995. To directly compare time functions, or to group them by size, depth, or region, it is essential to scale them to remove the effect of moment, which varies by more than 3 orders of magnitude for these events. For each event we also computed short-period stacks of P waves recorded by west coast regional arrays. The comparison of broadband with short-period stacks yields a considerable advantage, enabling more reliable measurement of event duration. A more accurate estimate of the duration better constrains the scaling procedure to remove the effect of moment, producing scaled time functions with both correct timing and amplitude. We find only subtle differences in the broadband time-function shape with moment, indicating successful scaling and minimal effects of attenuation at the periods considered here. The average shape of the envelopes of the short-period stacks is very similar to the average broadband time function. The main variations seen with depth are (1) a mild decrease in duration with increasing depth, (2) greater asymmetry in the time functions of intermediate events compared to deep ones, and (3) unexpected complexity and late moment release for events between 350 and 550 km, with seven of the eight events in that depth interval displaying markedly more complicated time functions with more moment release late in the rupture than most events above or below. The first two results are broadly consistent with our previous studies, while the third is reported here for the first time. The greater complexity between 350 and 550 km suggests greater heterogeneity in
Effects of weak periodic pressure waves on time to ignition of fuel mixtures
Vainshtein, P.; Gutfinger, C.
2001-09-01
The accumulation of small-amplitude gas dynamic perturbations accelerates the process of self-ignition of a homogeneous explosive mixture. In the present paper the cumulative effect of forced acoustic oscillations is studied when timescales of piston motions in a closed cylinder are comparable with the acoustic timescale. It is shown that the most significant shortening of the time to ignition takes place in a resonant system, where periodic shock waves travel back and forth in the cylinder.
Electron Transport in Graphene-Based Double-Barrier Structure under a Time Periodic Field
Institute of Scientific and Technical Information of China (English)
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.
Carvalho Filho,José Luiz S de; Arie F Blank; Péricles B. Alves; Polyana A.D. Ehlert; Alberto S. de Melo; Sócrates C. H. Cavalcanti; Arrigoni-Blank, Maria de Fátima; Silva-Mann,Renata
2006-01-01
Ocimum basilicum L. essential oil with high concentration of linalool is valuable in international business. O. basilicum essential oil is widely used as seasoning and in cosmetic industry. To assure proper essential oil yield and quality, it is crucial to determine which environmental and processing factors are affecting its composition. The goal of our work is to evaluate the effects of harvesting time, temperature, and drying period on the yield and chemical composition of O. basilicum ess...
A Coupled Far-Field Formulation for Time-Periodic Numerical Problems in Fluid Dynamics
Indian Academy of Sciences (India)
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.
Asymptotic Weighted-Periodicity of the Impulsive Parabolic Equation with Time Delay
Institute of Scientific and Technical Information of China (English)
Jin-liang Wang; Hui-feng Li
2007-01-01
The main aim of this paper is to investigate the effects of the impulse and time delay on a type of parabolic equations. In view of the characteristics of the equation, a particular iteration scheme is adopted.The results show that Under certain conditions on the coefficients of the equation and the impulse, the solution oscillates in a particular manner-called "asymptotic weighted-periodicity".
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.
Modeling the time-periodicity of in-degree distributions in scientific citation networks
Liu, Qi; Xie, Zonglin; Dong, Enming; Li, Jianping
2016-01-01
In a range of citation networks, the in-degree distributions boast time-periodicity---the distributions of citations per article published each year present similar scale-free tails. This phenomenon can be regarded as a consequence of the emergence of hot topics and the existence of the "burst" phenomenon. With this inference considered, a geometric model based on our previous study is established, in which the sizes of the influence zones of nodes follow the same power-law distribution and decrease with their ages. The model successfully reproduces the time-periodicity of the in-degree distributions of the empirical data, and accounts for the presence of citation burst as well. Moreover, a reasonable explanation for the emergence of the scale-free tails by regarding the citation behavior between articles as a "yes/no" experiment is presented. The model can also predict the time-periodicity of the local clustering coefficients, which indicates that the model is a good tool in researches on the evolutionary me...
MULTI BAND INSAR ANALYSIS OF SUBSIDENCE DEVELOPMENT BASED ON THE LONG PERIOD TIME SERIES
2015-01-01
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 t...
EFFECT OF MAGNETIZATION OF WATER ON INDUCTION TIME AND GROWTH PERIOD OF NATURAL GAS HYDRATE
Institute of Scientific and Technical Information of China (English)
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.
Institute of Scientific and Technical Information of China (English)
Du Lu-Chun; Mei Dong-Cheng
2009-01-01
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.
Transfer-matrix approach for finite-difference time-domain simulation of periodic structures.
Deinega, Alexei; Belousov, Sergei; Valuev, Ilya
2013-11-01
Optical properties of periodic structures can be calculated using the transfer-matrix approach, which establishes a relation between amplitudes of the wave incident on a structure with transmitted or reflected waves. The transfer matrix can be used to obtain transmittance and reflectance spectra of finite periodic structures as well as eigenmodes of infinite structures. Traditionally, calculation of the transfer matrix is performed in the frequency domain and involves linear algebra. In this work, we present a technique for calculation of the transfer matrix using the finite-difference time-domain (FDTD) method and show the way of its implementation in FDTD code. To illustrate the performance of our technique we calculate the transmittance spectra for opal photonic crystal slabs consisting of multiple layers of spherical scatterers. Our technique can be used for photonic band structure calculations. It can also be combined with existing FDTD methods for the analysis of periodic structures at an oblique incidence, as well as for modeling point sources in a periodic environment.
Directory of Open Access Journals (Sweden)
Kuang-Jung Chen
2007-01-01
Full Text Available In this study, geomagnetic data of the Lunping observatory from 1993 to 2000 are utilized for computing the amplitude variation of short-period geomagnetic total intensity data, using the complex demodulation method (CD method. In order to compare these time changes with seismicity, earthquakes that occurred within 150 km of Lunping, with magnitude ML greater than 3.0, are located. The total sum of those earthquakes, summed month by month, is correlated with the modulus. After removing seasonal effect, our results show that the modulus of periods 24, 12, and 8 hr reveals a notable change that seems to be related to the total sum of events within the whole study period. One possible precursor is found 6 months prior to the 1999 high seismicity. The modulus for the periods 24, 12, and 8 hr increased gradually from the beginning of 1999 to August 1999. After earthquake occurrence the modulus decreased again to a normal level. We propose that this notable increase might be related to a preparation process for this strong earthquake.
Detection of faults in rotating machinery using periodic time-frequency sparsity
Ding, Yin; He, Wangpeng; Chen, Binqiang; Zi, Yanyang; Selesnick, Ivan W.
2016-11-01
This paper addresses the problem of extracting periodic oscillatory features in vibration signals for detecting faults in rotating machinery. To extract the feature, we propose an approach in the short-time Fourier transform (STFT) domain where the periodic oscillatory feature manifests itself as a relatively sparse grid. To estimate the sparse grid, we formulate an optimization problem using customized binary weights in the regularizer, where the weights are formulated to promote periodicity. In order to solve the proposed optimization problem, we develop an algorithm called augmented Lagrangian majorization-minimization algorithm, which combines the split augmented Lagrangian shrinkage algorithm (SALSA) with majorization-minimization (MM), and is guaranteed to converge for both convex and non-convex formulation. As examples, the proposed approach is applied to simulated data, and used as a tool for diagnosing faults in bearings and gearboxes for real data, and compared to some state-of-the-art methods. The results show that the proposed approach can effectively detect and extract the periodical oscillatory features.
Nezhel'skaya, L. A.
2016-09-01
A flow of physical events (photons, electrons, and other elementary particles) is studied. One of the mathematical models of such flows is the modulated MAP flow of events circulating under conditions of unextendable dead time period. It is assumed that the dead time period is an unknown fixed value. The problem of estimation of the dead time period from observations of arrival times of events is solved by the method of maximum likelihood.
Duan, Gaopeng; Xiao, Feng; Wang, Long
2017-01-23
This paper focuses on the average consensus of double-integrator networked systems based on the asynchronous periodic edge-event triggered control. The asynchronous property lies in the edge event-detecting procedure. For different edges, their event detections are performed at different times and the corresponding events occur independently of each other. When an event is activated, the two adjacent agents connected by the corresponding link sample their relative state information and update their controllers. The application of incidence matrix facilitates the transformation of control objects from the agent-based to the edge-based. Practically, due to the constraints of network bandwidth and communication distance, agents usually cannot receive the instantaneous information of some others, which has an impact on the system performance. Hence, it is necessary to investigate the presence of communication time delays. For double-integrator multiagent systems with and without communication time delays, the average state consensus can be asynchronously achieved by designing appropriate parameters under the proposed event-detecting rules. The presented results specify the relationship among the maximum allowable time delays, interaction topologies, and event-detecting periods. Furthermore, the proposed protocols have the advantages of reduced communication costs and controller-updating costs. Simulation examples are given to illustrate the proposed theoretical results.
Bergeot, Nicolas; Chevalier, Jean-Marie; Bruyninx, Carine
2015-04-01
Several agencies are routinely monitoring the vertical Total Electron Content (vTEC) using GNSS data. Derived maps are available with different latencies, area extents, and grid/time resolutions. However, no high-resolution maps are publically available over Europe in near real-time. In this frame, the Royal Observatory of Belgium (ROB) developed the ROB-IONO software which takes advantage of the dense EUREF Permanent GNSS Network (EPN) to monitor the ionosphere. The main ROB products consist of ionospheric vTEC maps over Europe and their variability estimated in near real-time every 15 min on 0.5° x 0.5° grids using GPS observations. The maps are available online with a latency of ~3 min in the IONEX format at ftp://gnss.oma.be and as interactive web pages at www.gnss.be. During normal ionospheric activity, the ROB-TEC maps show a good agreement with widely used post-processed global products from IGS, CODE and ESA, with mean differences of 1.3 ± 0.9, 0.6 ± 0.7 and 0.4 ± 1.6 TECu respectively for the period 2012 to mid-2013. For a disturbed period, such as the 2003 Halloween ionospheric storm, the mean differences with IGS, CODE and ESA maps are respectively 0.9 ± 2.2, 0.1 ± 2.0 and 0.6 ± 6.8 TECu, with maximum differences (>38 TECu) occurring during the major phase of the storm. These differences are due to the lower resolution of global products in time and space compared to the ROB-TEC maps. A description of two recent events, on March 17, 2013 and February 27, 2014 highlights the capability of the method adopted to detect in near real-time abnormal ionospheric behaviour over Europe. The potential of the variability maps as an indicator of rapid ionospheric variations during the 15 min of observations is also highlighted. More than 30 ionospheric events associated with Space weather were detected during the period 2012-2014. The ionospheric perturbations are associated with Coronal Mass Ejections (CMEs, ~70% of the time), active geomagnetic conditions
Period coded phase shifting strategy for real-time 3-D structured light illumination.
Wang, Yongchang; Liu, Kai; Hao, Qi; Lau, Daniel L; Hassebrook, Laurence G
2011-11-01
Phase shifting structured light illumination for range sensing involves projecting a set of grating patterns where accuracy is determined, in part, by the number of stripes. However, high pattern frequencies introduce ambiguities during phase unwrapping. This paper proposes a process for embedding a period cue into the projected pattern set without reducing the signal-to-noise ratio. As a result, each period of the high frequency signal can be identified. The proposed method can unwrap high frequency phase and achieve high measurement precision without increasing the pattern number. Therefore, the proposed method can significantly benefit real-time applications. The method is verified by theoretical and experimental analysis using prototype system built to achieve 120 fps at 640 × 480 resolution.
Kafka, K R P; Li, H; Yi, A; Cheng, J; Chowdhury, E A
2015-01-01
Time-resolved diffraction microscopy technique has been used to observe the formation of laser-induced periodic surface structures (LIPSS) from the interaction of a single femtosecond laser pulse (pump) with a nano-scale groove mechanically formed on a single-crystal Cu substrate. The interaction dynamics (0-1200 ps) was captured by diffracting a time-delayed, frequency-doubled pulse from nascent LIPSS formation induced by the pump with an infinity-conjugate microscopy setup. The LIPSS ripples are observed to form sequentially outward from the groove edge, with the first one forming after 50 ps. A 1-D analytical model of electron heating and surface plasmon polariton (SPP) excitation induced by the interaction of incoming laser pulse with the groove edge qualitatively explains the time-evloution of LIPSS formation.
Leakage-Aware Reallocation for Periodic Real-Time Tasks on Multicore Processors
Huang, Hongtao; Wang, Jijie; Lei, Siyu; Wu, Guowei
2010-01-01
It is an increasingly important issue to reduce the energy consumption of computing systems. In this paper, we consider partition based energy-aware scheduling of periodic real-time tasks on multicore processors. The scheduling exploits dynamic voltage scaling (DVS) and core sleep scheduling to reduce both dynamic and leakage energy consumption. If the overhead of core state switching is non-negligible, however, the performance of this scheduling strategy in terms of energy efficiency might degrade. To achieve further energy saving, we extend the static task scheduling with run-time task reallocation. The basic idea is to aggregate idle time among cores so that as many cores as possible could be put into sleep in a way that the overall energy consumption is reduced. Simulation results show that the proposed approach results in up to 20% energy saving over traditional leakage-aware DVS.
Dynamical systems analysis of fluid transport in time-periodic vortex ring flows
Shariff, Karim; Leonard, Anthony; Ferziger, Joel H.
2006-04-01
It is known that the stable and unstable manifolds of dynamical systems theory provide a powerful tool for understanding Lagrangian aspects of time-periodic flows. In this work we consider two time-periodic vortex ring flows. The first is a vortex ring with an elliptical core. The manifolds provide information about entrainment and detrainment of irrotational fluid into and out of the volume transported with the ring. The likeness of the manifolds with features observed in flow visualization experiments of turbulent vortex rings suggests that a similar process might be at play. However, what precise modes of unsteadiness are responsible for stirring in a turbulent vortex ring is left as an open question. The second situation is that of two leapfrogging rings. The unstable manifold shows striking agreement with even the fine features of smoke visualization photographs, suggesting that fluid elements in the vicinity of the manifold are drawn out along it and begin to reveal its structure. We suggest that interpretations of these photographs that argue for complex vorticity dynamics ought to be reconsidered. Recently, theoretical and computational tools have been developed to locate structures analogous to stable and unstable manifolds in aperiodic, or finite-time systems. The usefulness of these analogs is demonstrated, using vortex ring flows as an example, in the paper by Shadden, Dabiri, and Marsden [Phys. Fluids 18, 047105 (2006)].
Directory of Open Access Journals (Sweden)
Xiaofeng Gu
2013-09-01
Full Text Available The developmental transition from a vegetative to a reproductive phase (i.e., flowering is timed by the seasonal cue day length or photoperiod in many plant species. Through the photoperiod pathway, inductive day lengths trigger the production of a systemic flowering signal, florigen, to provoke the floral transition. FLOWERING LOCUS T (FT, widely conserved in angiosperms, is a major component of the mobile florigen. In the long-day plant Arabidopsis, FT expression is rhythmically activated by the output of the photoperiod pathway CONSTANS (CO, specifically at the end of long days. How FT expression is modulated at an adequate level in response to the long-day cue to set a proper flowering time remains unknown. Here, we report a periodic histone deacetylation mechanism for the photoperiodic modulation of FT expression. We have identified a plant-unique core structural component of an Arabidopsis histone deacetylase (HDAC complex. In long days, this component accumulates at dusk, and is recruited by a MADS-domain transcription factor to the FT locus specifically at the end of the day, leading to periodic histone deacetylation of FT chromatin at dusk. Furthermore, we found that at the end of long days CO activity not only activates FT expression but also enables HDAC-activity recruitment to FT chromatin to dampen the level of FT expression, and so prevent precocious flowering in response to the inductive long-day cue. These results collectively reveal a periodic histone deacetylation mechanism for the day-length control of flowering time in higher plants.
Gu, Xiaofeng; Wang, Yizhong; He, Yuehui
2013-09-01
The developmental transition from a vegetative to a reproductive phase (i.e., flowering) is timed by the seasonal cue day length or photoperiod in many plant species. Through the photoperiod pathway, inductive day lengths trigger the production of a systemic flowering signal, florigen, to provoke the floral transition. FLOWERING LOCUS T (FT), widely conserved in angiosperms, is a major component of the mobile florigen. In the long-day plant Arabidopsis, FT expression is rhythmically activated by the output of the photoperiod pathway CONSTANS (CO), specifically at the end of long days. How FT expression is modulated at an adequate level in response to the long-day cue to set a proper flowering time remains unknown. Here, we report a periodic histone deacetylation mechanism for the photoperiodic modulation of FT expression. We have identified a plant-unique core structural component of an Arabidopsis histone deacetylase (HDAC) complex. In long days, this component accumulates at dusk, and is recruited by a MADS-domain transcription factor to the FT locus specifically at the end of the day, leading to periodic histone deacetylation of FT chromatin at dusk. Furthermore, we found that at the end of long days CO activity not only activates FT expression but also enables HDAC-activity recruitment to FT chromatin to dampen the level of FT expression, and so prevent precocious flowering in response to the inductive long-day cue. These results collectively reveal a periodic histone deacetylation mechanism for the day-length control of flowering time in higher plants.
Geometric tools for solving the FDI problem for linear periodic discrete-time systems
Longhi, Sauro; Monteriù, Andrea
2013-07-01
This paper studies the problem of detecting and isolating faults in linear periodic discrete-time systems. The aim is to design an observer-based residual generator where each residual is sensitive to one fault, whilst remaining insensitive to the other faults that can affect the system. Making use of the geometric tools, and in particular of the outer observable subspace notion, the Fault Detection and Isolation (FDI) problem is formulated and necessary and solvability conditions are given. An algorithmic procedure is described to determine the solution of the FDI problem.
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.
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.
The time derivative of the kilohertz quasi-periodic oscillations in 4U 1636-53
Sanna, Andrea; Belloni, Tomaso; Altamirano, Diego
2012-01-01
We analysed all archival RXTE observations of the neutron-star low-mass X-ray binary 4U 1636-53 up to May 2010. In 528 out of 1280 observations we detected kilohertz quasi-periodic oscillations (kHz QPOs), with ~ 65% of these detections corresponding to the so-called lower kHz QPO. Using this QPO we measured, for the first time, the rate at which the QPO frequency changes as a function of QPO frequency. For this we used the spread of the QPO frequency over groups of 10 consecutive measurements, sampling timescales between 320 and 1600 s, and the time derivative of the QPO frequency over timescales of 32 to 160 s. We found that: (i) Both the QPO-frequency spread and the QPO time derivative decrease by a factor ~ 3 as the QPO frequency increases. (ii) The average value of the QPO time derivative decreases by a factor of ~ 2 as the timescale over which the derivative is measured increases from less than 64 s to 160 s. (iii) The relation between the absolute value of the QPO time derivative and the QPO frequency ...
On Bifurcating Time-Periodic Flow of a Navier-Stokes Liquid Past a Cylinder
Galdi, Giovanni P.
2016-10-01
We provide general sufficient conditions for the existence and uniqueness of branching out of a time-periodic family of solutions from steady-state solutions to the two-dimensional Navier-Stokes equations in the exterior of a cylinder. By separating the time-independent averaged component of the velocity field from its oscillatory one, we show that the problem can be formulated as a coupled elliptic-parabolic nonlinear system in appropriate and distinct function spaces, with the property that the relevant linearized operators become Fredholm of index 0. In this functional setting, the notorious difficulty of 0 being in the essential spectrum entirely disappears and, in fact, it is even meaningless. Our approach is different and, we believe, more natural and simpler than those proposed by previous authors discussing similar questions. Moreover, the latter all fail, when applied to the problem studied here.
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...
Directory of Open Access Journals (Sweden)
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.
时间序列周期模式挖掘的周期检测方法%Periodicity Detection Method of Periodic Pattern Mining in Time Series
Institute of Scientific and Technical Information of China (English)
王阅; 高学东; 武森; 陈敏
2009-01-01
周期是时间序列的重要特征之一,用于精确描述时间序列并预测其发展趋势.在现有周期模式挖掘算法中,周期长度由用户事先定义,忽略了噪声的存在.在ERP度量和时间弯曲算法的基础上,提出一种新的周期长度检测方法.该方法可以在时间轴上实现弯曲,包括延伸和平移.它受噪声干扰的影响较小,实验结果表明其性能优于原有周期检测算法.%Periodicity is an important feature for time series that can be used for describing time series exactly and predicting its development trends. In existing mining algorithms for periodic patterns, the periodicity length is user-specified in andvanc, and the presence of noise is not taken into account. Based on ERP(Edit distance with Real Penalty) measurement and time warping algorithm, this paper proposes a novel algorithm for periodicity length detection, which can realize warp on the time axis including extending and translation. It is less affected by noise interference. Experimental results show that the performance of this algorithm is better than existing periodicity detection algorithms.
Enhanced Transport of Passive Tracers In A Time Periodic Two-dimensional Flow
Boffetta, G.; Cencini, M.; Espa, S.; Musacchio, S.
, investigating systems in which the second condition is violated is much more inter- esting. With this purpose, some experiments have shown how superdiffusion arises in a two-dimensional quasi-geostrophic (planetary-type) flow, where particles can jump for very long time in the same direction performing a Levy flight (Castiglione et al., 2001 ). Moreover, two recent papers (Vulpiani, 1998; Solomon, 2001) show how, also in very simple two-dimensional, time and space periodic cellular flows,anomalous diffusive behaviours can appear. In this paper we present an experimental study of transport in an electromagnetically forced time periodic two-dimensional flow. The flow is generated by applying an electromagnetic forcing on a thin layer of an elec- trolyte solution and reveals in a square grid of alternating vortices. Time dependence can be easily obtained by changing the time dependence of the electric fields. In par- ticular, considering certain values of the imposed oscillation frequencies, particles can display very long jump. Particle Tracking Velocimetry (PTV) is used to measure the flow field. This technique is the most suitable for studying dispersion phenomena in a Lagrangian framework allowing the direct evaluation of particle displacements and related quantities (Cenedese, Querzoli; 2000). Moreover, due to the characteristics of the analyzed flow and to the improvement of the tracking procedure, we have been able to track a great number of particles for time intervals greater than the charac- teristic time-scales of the flow. In order to characterize the time correlations we will evaluate the so-called jumps probabilities with memory which represent the probabil- ities to jump in a given direction conditioned to having experienced jumps in the same direction at previous times. Such statistics will revealed very useful and suitable for detecting the onset of the aforementioned correlations. 2
Length of Growing Period over Africa: Variability and Trends from 30 Years of NDVI Time Series
Directory of Open Access Journals (Sweden)
Mohammed Y. Said
2013-02-01
Full Text Available The spatial distribution of crops and farming systems in Africa is determined by the duration of the period during which crop and livestock water requirements are met. The length of growing period (LGP is normally assessed from weather station data—scarce in large parts of Africa—or coarse-resolution rainfall estimates derived from weather satellites. In this study, we analyzed LGP and its variability based on the 1981–2011 GIMMS NDVI3g dataset. We applied a variable threshold method in combination with a searching algorithm to determine start- and end-of-season. We obtained reliable LGP estimates for arid, semi-arid and sub-humid climates that are consistent in space and time. This approach effectively mapped bimodality for clearly separated wet seasons in the Horn of Africa. Due to cloud contamination, the identified bimodality along the Guinea coast was judged to be less certain. High LGP variability is dominant in arid and semi-arid areas, and is indicative of crop failure risk. Significant negative trends in LGP were found for the northern part of the Sahel, for parts of Tanzania and northern Mozambique, and for the short rains of eastern Kenya. Positive trends occurred across western Africa, in southern Africa, and in eastern Kenya for the long rains. Our LGP analysis provides useful information for the mapping of farming systems, and to study the effects of climate variability and other drivers of change on vegetation and crop suitability.
Wu, Yanan; Gong, Yubing; Xu, Bo
2013-12-01
Recently, multiple coherence resonance induced by time delay has been observed in neuronal networks with constant coupling strength. In this paper, by employing Newman-Watts Hodgkin-Huxley neuron networks with time-periodic coupling strength, we study how the temporal coherence of spiking behavior and coherence resonance by time delay change when the frequency of periodic coupling strength is varied. It is found that delay induced coherence resonance is dependent on periodic coupling strength and increases when the frequency of periodic coupling strength increases. Periodic coupling strength can also induce multiple coherence resonance, and the coherence resonance occurs when the frequency of periodic coupling strength is approximately multiple of the spiking frequency. These results show that for periodic coupling strength time delay can more frequently optimize the temporal coherence of spiking activity, and periodic coupling strength can repetitively optimize the temporal coherence of spiking activity as well. Frequency locking may be the mechanism for multiple coherence resonance induced by periodic coupling strength. These findings imply that periodic coupling strength is more efficient for enhancing the temporal coherence of spiking activity of neuronal networks, and thus it could play a more important role in improving the time precision of information processing and transmission in neural networks.
Longhi, S
2012-01-01
Recent works [Y.D. Chong {\\it et al.}, Phys. Rev. Lett. {\\bf 105}, 053901 (2010); W. Wan {\\it et al.}, Science {\\bf 331}, 889 (2011)] have shown that the time-reversed process of lasing at threshold realizes a coherent perfect absorber (CPA). In a CPA, a lossy medium in an optical cavity with a specific degree of dissipation, equal in modulus to the gain of the lasing medium, can perfectly absorb coherent optical waves at discrete frequencies that are the time-reversed counterpart of the lasing modes. Here the concepts of time-reversal of lasing and CPA are extended for optical radiation emitted by a laser operated in an arbitrary (and generally highly-nonlinear) regime, i.e. for transient, chaotic or periodic coherent optical fields. We prove that any electromagnetic signal $E(t)$ generated by a laser system \\textbf{S} operated in an arbitrary regime can be perfectly absorbed by a CPA device $\\bf{S'}$ which is simply realized by placing inside \\textbf{S} a broadband linear absorber (attenuator) of appropriat...
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$...
Dynamical generalized Hurst exponent as a tool to monitor unstable periods in financial time series
Morales, Raffaello; Di Matteo, T.; Gramatica, Ruggero; Aste, Tomaso
2012-06-01
We investigate the use of the Hurst exponent, dynamically computed over a weighted moving time-window, to evaluate the level of stability/instability of financial firms. Financial firms bailed-out as a consequence of the 2007-2008 credit crisis show a neat increase with time of the generalized Hurst exponent in the period preceding the unfolding of the crisis. Conversely, firms belonging to other market sectors, which suffered the least throughout the crisis, show opposite behaviors. We find that the multifractality of the bailed-out firms increase at the crisis suggesting that the multi fractal properties of the time series are changing. These findings suggest the possibility of using the scaling behavior as a tool to track the level of stability of a firm. In this paper, we introduce a method to compute the generalized Hurst exponent which assigns larger weights to more recent events with respect to older ones. In this way large fluctuations in the remote past are less likely to influence the recent past. We also investigate the scaling associated with the tails of the log-returns distributions and compare this scaling with the scaling associated with the Hurst exponent, observing that the processes underlying the price dynamics of these firms are truly multi-scaling.
Reference value of long-time exercise test in the diagnosis of primary periodic paralysis
Institute of Scientific and Technical Information of China (English)
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.
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.
MULTI BAND INSAR ANALYSIS OF SUBSIDENCE DEVELOPMENT BASED ON THE LONG PERIOD TIME SERIES
Directory of Open Access Journals (Sweden)
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.
A Partial Backlogging Inventory Model with Time-Varying Demand During Shortage Period
Directory of Open Access Journals (Sweden)
Chen Mang
2010-11-01
Full Text Available Harris’s classic square root economic order quantity (EOQ model forms the basis for many other models that relax one or more of its assumptions. A key assumption of the basic EOQ model is that stockouts are not permitted. Due to the excess demands, stock-out situations may arise occasionally. Sometimes, shortages are permitted and they are backordered and satisfied in the very next replenishment. Therefore the objective of this paper is to develop a partial backlogging inventory model, and proposes a new algorithm to minimize the total cost, at the same time also propose the prediction method and algorithm of ordering period. Finally, a practical example of the numerical analysis is given.
Observations of the April 2002 Storm Period with TIMED-TIDI
Niciejewski, R.; Killeen, T.; Wu, Q.; Skinner, W.; Solomon, S.; Ortland, D.; Kafkalidis, J.; Gell, D.; Gablehouse, D.; Johnson, R.
2002-12-01
TIDI is meeting its basic requirement, which is to measure the global wind field in the mesosphere and lower thermosphere, the core study region. Since February 2002, TIDI has been in a routine science data-taking mode. During April 2002, TIMED was positioned at a high beta angle (angle between the plane of the satellite orbit and the Earth-Sun line) resulting in a series of TIDI measurements near the dusk/dawn terminator. The field of view of TIDI allows it to obtain measurements from pole to pole, while the repetition rate of the sky-scanner allows it to obtain several scans within the auroral oval region on each orbit. This paper will discuss TIDI measurements obtained during the April 2002 storm period, including OI (5577\\x8F) intensity data and neutral wind data sets.
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.
H2 control of discrete-time periodic systems with Markovian jumps and multiplicative noise
Ma, Hongji; Jia, Yingmin
2013-10-01
This paper addresses the problem of optimal and robust H2 control for discrete-time periodic systems with Markov jump parameters and multiplicative noise. To analyse the system performance in the presence of exogenous random disturbance, an H2 norm is firstly established on the basis of Gramian matrices. Further, under the condition of exact observability, a necessary and sufficient condition is presented for the solvability of H2 optimal control problem by means of a generalised Riccati equation. When the transition probabilities of jump parameter are incompletely measurable, an H2-guaranteed cost norm is exploited and the robust H2 controller is designed through a linear matrix inequality (LMI) optimisation approach. An example of a networked control system is supplied to illustrate the proposed results.
Energy Technology Data Exchange (ETDEWEB)
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...
Ordering of small particles in one-dimensional coherent structures by time-periodic flows
Pushkin, Dmitri; Shevtsova, Valentina
2011-01-01
Small particles transported by a fluid medium do not necessarily have to follow the flow. We show that for a wide class of time-periodic incompressible flows inertial particles have a tendency to spontaneously align in one-dimensional dynamic coherent structures. This effect may take place for particles so small that often they would be expected to behave as passive tracers and be used in PIV measurement technique. We link the particle tendency to form one-dimensional structures to the nonlinear phenomenon of phase locking. We propose that this general mechanism is, in particular, responsible for the enigmatic formation of the `particle accumulation structures' discovered experimentally in thermocapillary flows more than a decade ago and unexplained until now.
Zhou, Jun; Lu, Xinbiao; Qian, Huimin
2016-09-01
The paper reports interesting but unnoticed facts about irreducibility (resp., reducibility) of Flouqet factorisations and their harmonic implication in term of controllability in finite-dimensional linear continuous-time periodic (FDLCP) systems. Reducibility and irreducibility are attributed to matrix logarithm algorithms during computing Floquet factorisations in FDLCP systems, which are a pair of essential features but remain unnoticed in the Floquet theory so far. The study reveals that reducible Floquet factorisations may bring in harmonic waves variance into the Fourier analysis of FDLCP systems that in turn may alter our interpretation of controllability when the Floquet factors are used separately during controllability testing; namely, controllability interpretation discrepancy (or simply, controllability discrepancy) may occur and must be examined whenever reducible Floquet factorisations are involved. On the contrary, when irreducible Floquet factorisations are employed, controllability interpretation discrepancy can be avoided. Examples are included to illustrate such observations.
Low-thrust roundtrip trajectories to Mars with one-synodic-period repeat time
Okutsu, Masataka; Landau, Damon F.; Rogers, Blake A.; Longuski, James M.
2015-05-01
Cycler trajectories-both ballistic and powered-are reported in the literature in which there are two-vehicle, three-vehicle, and four-vehicle cases. Such trajectories permit the installation of cycler vehicles which provide safe and comfortable living conditions for human space travel between Earth and Mars during every synodic opportunity. The question the present paper answers is a logical, obvious one: Does a single-vehicle, one-synodic-period cycler exist? The answer is yes: such a trajectory can be flown-but only with a high-power electric propulsion system. In our example, it is found that "stopover" trajectories that spend 30 days in orbit about Earth and 30 days about Mars, and return astronauts to Earth in one synodic period require a 90-t power generator with a power level of 11 MWe. Fortuitously, and in lieu of using chemical propulsion, the high power level of the electric propulsion system would also be effective in hauling the cargo payload via a spiral trajectory about the Earth. But because one synodic period is not enough for the cycler vehicle to fly both the interplanetary trajectories and the Earth-spiral trajectories, we suggest developing two nuclear power generators, which could alternate flying the interplanetary trajectories and the Earth-spiral trajectories. Once these power generators are launched and begin operating in space, the mass requirement in seven subsequent missions (over a period of 15 years beginning in 2022) would be modest at 250-300 metric tons to low-Earth orbit per mission. Thus two cargo launches of NASA's Space Launch System and one crew launch of the Falcon Heavy, for example, would be adequate to maintain support for each consecutive mission. Although we propose developing two sets of electric propulsion systems to account for the Earth-spiral phases, only one vehicle is flown on a heliocentric trajectory at any given time. Thus, our low-thrust stopover cycler with zero encounter velocities falls into a category of a
Borisov, A A; Bruevich, V V; Rozgacheva, I K; Shimanovskaya, E V
2015-01-01
We applied the method of continuous wavelet-transform to high-quality time-frequency analysis to the sets of observations of relative sunspot numbers. Wavelet analysis of these data reveals the following pattern: at the same time there are several activity cycles whose periods vary widely from the quasi biennial up to the centennial period. These relatively low-frequency periodic variations of the solar activity gradually change the values of periods of different cycles in time. This phenomenon can be observed in every cycle of activity.
DEFF Research Database (Denmark)
liu, weiwei; Huangfu, Hao; Xiong, Jing
2014-01-01
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......, under the synergistic feedback effect of the physical and psychological adaption modes. The time period of thermal adaption increased to 13 days, if only the feedback effect of the physical adaption mode was accounted for. The difference between the two values of the time period of thermal adaption...... 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 temperature...
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.
Directory of Open Access Journals (Sweden)
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.
Directory of Open Access Journals (Sweden)
Jennifer Tsui
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
Time-Based Measurement of Personal Mite Allergen Bioaerosol Exposure over 24 Hour Periods.
Directory of Open Access Journals (Sweden)
Euan R Tovey
Full Text Available 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
Directory of Open Access Journals (Sweden)
Kitajima,Takuji
2006-06-01
Full Text Available
To evaluate recent improvements in lung cancer screening, we compared the results of recently conducted lung cancer screening with those of a previous screening. This study compared the survival of lung cancer patients detected by lung cancer screening conducted between 1976 and 1984 (early period with that conducted between 1989 and 1997 (late period. Two hundred seventy-six patients with lung cancer were detected in the early period and 541 patients with lung cancer were detected in the late period. The median survival time (late : 49.8 vs. early : 27.8 months and the 5-year survival rate (late : 47.8 vs. early : 34.8% of the patients with lung cancer detected in the late period were significantly better than those in the early period (p = 0.0054. Among patients undergoing resection, the proportion of pathological stage I patients in the late period was significantly higher than that in the early period (late : 60.8 vs. early : 54.9%, p = 0.005. Multivariate analysis showed that the screening time period was a significant prognostic factor (hazard ratio = 0.685, 95% confidence interval : 0.563-0.832, p = 0.0002. These results were consistent with the findings of case-control studies of lung cancer screening programs in the late period recently conducted in Japan, which also showed a greater efficacy for screening than for previous case-control studies in the early period.
Kitajima, Takuji; Nishii, Kenji; Ueoka, Hiroshi; Shibayama, Takuo; Gemba, Kenichi; Kodani, Tsuyoshi; Kiura, Katsuyuki; Tabata, Masahiro; Hotta, Katsuyuki; Tanimoto, Mitsune; Sobue, Tomotaka
2006-06-01
To evaluate recent improvements in lung cancer screening, we compared the results of recently conducted lung cancer screening with those of a previous screening. This study compared the survival of lung cancer patients detected by lung cancer screening conducted between 1976 and 1984 (early period) with that conducted between 1989 and 1997 (late period). Two hundred seventy-six patients with lung cancer were detected in the early period and 541 patients with lung cancer were detected in the late period. The median survival time (late : 49.8 vs. early : 27.8 months) and the 5-year survival rate (late : 47.8 vs. early : 34.8%) of the patients with lung cancer detected in the late period were significantly better than those in the early period (p = 0.0054). Among patients undergoing resection, the proportion of pathological stage I patients in the late period was significantly higher than that in the early period (late : 60.8 vs. early : 54.9%, p = 0.005). Multivariate analysis showed that the screening time period was a significant prognostic factor (hazard ratio = 0.685, 95% confidence interval : 0.563-0.832, p = 0.0002). These results were consistent with the findings of case-control studies of lung cancer screening programs in the late period recently conducted in Japan, which also showed a greater efficacy for screening than for previous case-control studies in the early period.
Estimating return periods of extreme values from relatively short time series of winds
Jonasson, Kristjan; Agustsson, Halfdan; Rognvaldsson, Olafur; Arfeuille, Gilles
2013-04-01
An important factor for determining the prospect of individual wind farm sites is the frequency of extreme winds at hub height. Here, extreme winds are defined as the value of the highest 10 minutes averaged wind speed with a 50 year return period, i.e. annual exceeding probability of 2% (Rodrigo, 2010). A frequently applied method to estimate winds in the lowest few hundred meters above ground is to extrapolate observed 10-meter winds logarithmically to higher altitudes. Recent study by Drechsel et al. (2012) showed however that this methodology is not as accurate as interpolating simulated results from the global ECMWF numerical weather prediction (NWP) model to the desired height. Observations of persistent low level jets near Colima in SW-Mexico also show that the logarithmic approach can give highly inaccurate results for some regions (Arfeuille et al., 2012). To address these shortcomings of limited, and/or poorly representative, observations and extrapolations of winds one can use NWP models to dynamically scale down relatively coarse resolution atmospheric analysis. In the case of limited computing resources one has typically to make a compromise between spatial resolution and the duration of the simulated period, both of which can limit the quality of the wind farm siting. A common method to estimate maximum winds is to fit an extreme value distribution (e.g. Gumbel, gev or Pareto) to the maximum values of each year of available data, or the tail of these values. If data are only available for a short period, e.g. 10 or 15 years, then this will give a rather inaccurate estimate. It is possible to deal with this problem by utilizing monthly or weekly maxima, but this introduces new problems: seasonal variation, autocorrelation of neighboring values, and increased discrepancy between data and fitted distribution. We introduce a new method to estimate return periods of extreme values of winds at hub height from relatively short time series of winds, simulated
Lee, Dongwook; Kim, JongWon
2003-11-01
Streaming media applications over mobile IP networks suffer from playback disruptions resulting from handoff blackout period as well as bandwidth fluctuation. To overcome buffer shortage, pre-buffering technique can be adopted where the client stores sufficient amount of stream in advance. However, under the mobile IP handoff that may take up to several seconds, it is extremely difficult to sustain seamless playback. Inaccurate and conservative choice on the required buffering size can waste limited latency budget, resulting in quality degradation. In this paper, we are extending--from smooth handoff to fast handoff of mobile IPv6--the transient time analysis recently proposed to approximate transient time durations, STP (silent time period) and UTP (unstable time period). The approximated time periods are utilized to estimate the required buffering buffer size accurately. Network simulation result evaluted under simplified buffering strategies shows that the proposed scheme can provide appropriate guideline on the buffer parameters and thus can improve seamless streaming.
Dodd, Antony N; Dalchau, Neil; Gardner, Michael J; Baek, Seong-Jin; Webb, Alex A R
2014-01-01
A circadian rhythm matched to the phase and period of the day-night cycle has measurable benefits for land plants. We assessed the contribution of circadian period to the phasing of cellular events with the light : dark cycle. We also investigated the plasticity of circadian period within the Arabidopsis circadian oscillator. We monitored the circadian oscillator in wild-type and circadian period mutants under light : dark cycles of varying total duration. We also investigated changes in oscillator dynamics during and after the transition from light : dark cycles to free running conditions. Under light : dark cycles, dawn and dusk were anticipated differently when the circadian period was not resonant with the environmental period ('T cycle'). Entrainment to T cycles differing from the free-running period caused a short-term alteration in oscillator period. The transient plasticity of period was described by existing mathematical models of the Arabidopsis circadian network. We conclude that a circadian period resonant with the period of the environment is particularly important for anticipation of dawn and the timing of nocturnal events; and there is short-term and transient plasticity of period of the Arabidopsis circadian network.
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.
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.
Directory of Open Access Journals (Sweden)
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.
Platelet aggregation responses vary over a period of time in healthy controls.
Refaai, Majed A; Frenkel, Eugene; Sarode, Ravi
2010-01-01
Platelet aggregation study is performed to investigate platelet function abnormality. A normal healthy control sample is usually run with the patient sample as a quality control measure. At our institution, we observed variations in platelet aggregation responses in our normal repeat controls. Therefore, we analysed aggregation parameters in these controls. Whole blood aggregation studies were performed with adenosine diphosphate (ADP), arachidonic acid (AA), collagen and ristocetin. Adenosine triphosphate (ATP) secretion was also measured simultaneously by leuciferin-leuciferase reaction. During a 5-year period, a total of 86 studies were performed on seven controls. Aggregations were within the acceptable range in 67% of the time. Collagen was the most affected agonist in our study. On five occasions, four controls had subnormal aggregations with two agonists. All abnormal responses were hypoaggregation except for two who had hyperaggregation with collagen and AA. Only one out of seven controls was always normal. In the presence of a subnormal control result, a new control was run before releasing the patient's platelet aggregation results. These findings suggest that many physiological factors, other than medications, may affect platelet function even in normal individuals. Therefore, a repeat study at a later date to demonstrate a reproducible abnormality would be prudent before labeling a patient's platelets abnormal.
Time Periodic Electroosmotic Flow of The Generalized Maxwell Fluids in a Semicircular Microchannel
Institute of Scientific and Technical Information of China (English)
BAO Li-Ping; JIAN Yong-Jun; CHANG Long; SU Jie; ZHANG Hai-Yan; LIU Quan-Sheng
2013-01-01
Analytical solutions are presented using method of separation of variables for the time periodic electroosmotic flow (EOF) of linear viscoelastic fluids in semicircular microchannel.The linear viscoelastic fluids used here are described by the general Maxwell model.The solution involves analytically solving the linearized Poisson-Boltzmann (P-B) equation,together with the Cauchy momentum equation and the general Maxwell constitutive equation.By numerical computations,the influences of electric oscillating Reynolds number Re and Deborah number De on velocity amplitude are presented.For small Re,results show that the larger velocity amplitudeis confined to the region near the charged wall when De is small.With the increase of the Deborah number De,the velocity far away the charged wall becomes larger for large Deborah number De.However,for larger Re,the oscillating characteristic of the velocity amplitude occurs and becomes significant with the increase of De,especially for larger Deborah number.
The High Time Resolution Universe Survey - IX: Polarimetry of long-period pulsars
Tiburzi, C; Bailes, M; Bates, S D; Bhat, N D R; Burgay, M; Burke-Spolaor, S; Champion, D; Coster, P; D'Amico, N; Keith, M J; Kramer, M; Levin, L; Milia, S; Ng, C; Possenti, A; Stappers, B W; Thornton, D; van Straten, W
2013-01-01
We present a polarimetric analysis of 49 long-period pulsars discovered as part of the High Time Resolution Universe (HTRU) southern survey. The sources exhibit the typical characteristics of "old" pulsars, with low fractional linear and circular polarisation and narrow, multicomponent profiles. Although the position angle swings are generally complex, for two of the analysed pulsars (J1622-3751 and J1710-2616) we obtained an indication of the geometry via the rotating vector model. We were able to determine a value of the rotation measure (RM) for 34 of the sources which, when combined with their dispersion measures (DM), yields an integrated magnetic field strength along the line of sight. With the data presented here, the total number of values of RM associated to pulsars discovered during the HTRU southern survey sums to 51. The RMs are not consistent with the hypothesis of a counter-clockwise direction of the Galactic magnetic field within an annulus included between 4 and 6 kpc from the Galactic centre....
Chen, J. H.; Wasserburg, G. J.; Ku, T.-L.; Edwards, R. Lawrence
1987-01-01
The development of mass spectrometric techniques for determination of Th-230 abundance has made it possible to reduce analytical errors in (U-238)-(U-234)-(Th-230) dating of corals even with very small samples. Samples of 6 x 10 to the 8th atoms of Th-230 can be measured to an accuracy of + or - 3 percent (2sigma), and 3 x 10 to the 10th atoms of Th-230 can be measured to an accuracy of + or - 0.2 percent. The time range over which useful age data on corals can be obtained now ranges from about 50 to about 500,000 years. For young corals, this approach may be preferable to C-14 dating. The precision with which the age of a coral can now be determined should make it possible to critically test the Milankovitch hypothesis concerning Pleistocene climate fluctuations. Analyses of a number of corals that grew during the last interglacial period yield ages of 122,000 to 130,000 years. The ages coincide with, or slightly post-date, the summer solar insolation high at 65 deg N latitude which occurred 128,000 years ago. This supports the idea that changes in Pleistocene climate can be the result of variations in the distribution of solar insolation caused by changes in the geometry of the earth's orbit and rotation axis.
Resonant cyclotron acceleration of particles by a time periodic singular flux tube
Asch, Joachim; Stovicek, Pavel
2010-01-01
We study the dynamics of a classical nonrelativistic charged particle moving on a punctured plane under the influence of a homogeneous magnetic field and driven by a periodically time-dependent singular flux tube through the hole. We observe an effect of resonance of the flux and cyclotron frequencies. The particle is accelerated to arbitrarily high energies even by a flux of small field strength which is not necessarily encircled by the cyclotron orbit; the cyclotron orbits blow up and the particle oscillates between the hole and infinity. We support this observation by an analytic study of an approximation for small amplitudes of the flux which is obtained with the aid of averaging methods. This way we derive asymptotic formulas that are afterwards shown to represent a good description of the accelerated motion even for fluxes which are not necessarily small. More precisely, we argue that the leading asymptotic terms may be regarded as approximate solutions of the original system in the asymptotic domain as...
Prathap Reddy, K.
2016-11-01
An ‘electrostatic bathtub potential’ is defined and analytical expressions for the time period and amplitude of charged particles in this potential are obtained and compared with simulations. These kinds of potentials are encountered in linear electrostatic ion traps, where the potential along the axis appears like a bathtub. Ion traps are used in basic physics research and mass spectrometry to store ions; these stored ions make oscillatory motion within the confined volume of the trap. Usually these traps are designed and studied using ion optical software, but in this work the bathtub potential is reproduced by making two simple modifications to the harmonic oscillator potential. The addition of a linear ‘k 1|x|’ potential makes the simple harmonic potential curve steeper with a sharper turn at the origin, while the introduction of a finite-length zero potential region at the centre reproduces the flat region of the bathtub curve. This whole exercise of modelling a practical experimental situation in terms of a well-known simple physics problem may generate interest among readers.
DEFF Research Database (Denmark)
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...
PERIODIC SOLUTIONS FOR A DISCRETE TIME RATIO-DEPENDENT TWO PREDATOR-ONE PREY SYSTEM
Institute of Scientific and Technical Information of China (English)
柏灵; 范猛; 王克
2004-01-01
In this paper, we consider a three-species ratio-dependent predator-prey model governed by difference equations with periodic coefficients. By using the method of coincidence degree, we discuss the existence of positive periodic solutions of this system, a set of easily verifiable sufficient conditions are derived.
Directory of Open Access Journals (Sweden)
Xing Yin
2011-01-01
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-dependent asymptotical stability of these systems. Two examples illustrate the exactness of the proposed criteria.
Jhun, Hyung-Joon; Kim, Ho; Cho, Sung-Il
2011-05-01
We examined time trend and age-period-cohort effects on acute myocardial infarction (AMI) mortality in Korean adults from 1988 to 2007. Annual AMI mortality data and population statistics from 1988 to 2007 were obtained from the STATISTICS KOREA website. Age adjusted mortality for four 5-yr calendar periods (1988-1992 to 2003-2007) was calculated by direct standardization using the Year 2000 WHO world standard population. A log-linear Poisson regression model was used to estimate age, period, and cohort effects on AMI mortality. In both genders, age-adjusted AMI mortality increased from period one (1988-1992) to period three (1998-2002) but decreased in period four (2003-2007). An exponential age effect was noted in both genders. The rate ratio of the cohort effect increased up to the 1943 birth cohort and decreased gradually thereafter, and the rate ratio of the period effect increased up to period three (1998-2002) and decreased thereafter. Our results suggest that AMI mortality in Korean adults has decreased since the period 1998-2002 and age, period, and cohort effects have influenced on AMI mortality.
Period-independent novel circadian oscillators revealed by timed exercise and palatable meals
Danilo E. F. L. Flôres; Crystal N. Bettilyon; Shin Yamazaki
2016-01-01
The mammalian circadian system is a hierarchical network of oscillators organized to optimally coordinate behavior and physiology with daily environmental cycles. The suprachiasmatic nucleus (SCN) of the hypothalamus is at the top of this hierarchy, synchronizing to the environmental light-dark cycle, and coordinates the phases of peripheral clocks. The Period genes are critical components of the molecular timekeeping mechanism of these clocks. Circadian clocks are disabled in Period1/2/3 tri...
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 ...
DEFF Research Database (Denmark)
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...
DEFF Research Database (Denmark)
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...
Institute of Scientific and Technical Information of China (English)
Yao-lin Jiang
2003-01-01
In this paper we presented a convergence condition of parallel dynamic iteration methods for a nonlinear system of differential-algebraic equations with a periodic constraint.The convergence criterion is decided by the spectral expression of a linear operator derivedfrom system partitions. Numerical experiments given here confirm the theoretical work ofthe paper.
Cycle slipping in nonlinear circuits under periodic nonlinearities and time delays
Smirnova, Vera; Proskurnikov, Anton; Utina, Natalia V.
2014-01-01
Phase-locked loops (PLL), Costas loops and other synchronizing circuits are featured by the presence of a nonlinear phase detector, described by a periodic nonlinearity. In general, nonlinearities can cause complex behavior of the system such multi-stability and chaos. However, even phase locking ma
Directory of Open Access Journals (Sweden)
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.
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.
Institute of Scientific and Technical Information of China (English)
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.
Li, Bing; Li, Yongkun; Zhang, Xuemei
2016-01-01
In this paper, by using the existence of the exponential dichotomy of linear dynamic equations on time scales and the theory of calculus on time scales, we study the existence and global exponential stability of periodic solutions for a class of n-dimensional neutral dynamic equations on time scales. We also present an example to illustrate the feasibility of our results. The results of this paper are completely new and complementary to the previously known results even in both the case of differential equations (time scale [Formula: see text]) and the case of difference equations (time scale [Formula: see text]).
Formulation of a Combined Transportation and Inventory Optimization Model with Multiple Time Periods
Directory of Open Access Journals (Sweden)
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
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...
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...
PERIODIC SOLUTIONS FOR GENERALIZED PREDATOR-PREY SYSTEMS WITH TIME DELAY AND DIFFUSION
Institute of Scientific and Technical Information of China (English)
李必文
2004-01-01
A set of easily verifiable sufficient conditions are derived for the existence of positive periodic solutions for delayed generalized predator-prey dispersion system x'1 (t) = x1 (t)g1 (t, x1 (t) ) - a1 (t)y(t)p1 (x1 (t) ) + D1 (t)(x2(t) - x1 (t) ),x'2 (t) = x2 (t)g2 (t, x2 (t) ) - a2 (t)y(t)p2 (x2 (t) ) + D2(t)(x1 (t) - x2 (t)),y' (t) = y(t) {-h(t, y(t) ) + b1 (t)p1 (x1 (t - τ1 ) ) + b2(t)p2(x2(t - τ2))],where ai(t), bi(t) and Di(t)(i = 1, 2) are positive continuous T-periodic functions, gi(t, xi)(i = 1,2) and h(t,y) are continuous and T-periodic with respect to t and h(t,y) ＞ 0 for y ＞ 0, t, y ∈ R, pi(x)(i = 1, 2) are continuous and monotonously increasing functions, and pi(xi) ＞ 0 for xi ＞ 0.
Periodic Solution of a Nonautonomous Diffusive Food Chain System of Three Species with Time Delays
Institute of Scientific and Technical Information of China (English)
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.
The time-periodic diffusive competition models with a free boundary and sign-changing growth rates
Wang, Mingxin; Zhang, Yang
2016-10-01
To understand the spreading of invasive and native species, in this paper we consider the diffusive competition models with a free boundary in the heterogeneous time-periodic environments, in which the variable intrinsic growth rates of these two species change signs and may be very negative in some large regions. We study the spreading-vanishing dichotomy, long-time dynamical behavior of solution, sharp criteria for spreading and vanishing, and estimates of the asymptotic spreading speed of the free boundary. Moreover, we establish the existence of positive solutions to a T-periodic boundary value problem of the diffusive competition system with sign-changing growth rates in the half line.
Zu, Penghe; Chen, Long; Xin, Jack
2015-09-01
The minimal speeds (c∗) of the Kolmogorov-Petrovsky-Piskunov (KPP) fronts at small diffusion (ɛ ≪ 1) in a class of time-periodic cellular flows with chaotic streamlines is investigated in this paper. The variational principle of c∗ reduces the computation to that of a principle eigenvalue problem on a periodic domain of a linear advection-diffusion operator with space-time periodic coefficients and small diffusion. To solve the advection dominated time-dependent eigenvalue problem efficiently over large time, a combination of spectral methods and finite element, as well as the associated fast solvers, are utilized to accelerate computation. In contrast to the scaling c∗ = O(ɛ 1 / 4) in steady cellular flows, a new relation c∗ = O(1) as ɛ ≪ 1 is revealed in the time-periodic cellular flows due to the presence of chaotic streamlines. Residual propagation speed emerges from the Lagrangian chaos which is quantified as a sub-diffusion process.
McKay, Michael T.; Cole, Jon C.; Sumnall, Harry R.; Goudie, Andrew J.
2012-01-01
Time perspective is a cognitive-motivational construct, which has been shown to be related to decision-making, motivation and adjustment. The majority of research into time perspective has been conducted in college students and/or general population samples. Focus groups were held as part of a larger investigation into the relationship between…
THE SURVIVAL PROBABILITY IN FINITE TIME PERIOD IN FULLY DISCRETE RISK MODEL
Institute of Scientific and Technical Information of China (English)
ChengShixue; WuBiao
1999-01-01
The probabilities of the following events are first discussed in this paper: the insurance company survives to any fixed time k and the surplus at time k equals x≥1. The formulas for calculating such probabilities are deduced through analytical and probabilistic arguments respectively. Finally, other probability laws relating to risk are determined based on the probabilities mentioned above.
Energy Technology Data Exchange (ETDEWEB)
Kim, Nakwoo, E-mail: nkim@khu.ac.kr
2015-03-06
We consider scalar fields which are coupled to Einstein gravity with a negative cosmological constant, and construct periodic solutions perturbatively. In particular, we study tachyonic scalar fields whose mass is at or above the Breitenlohner–Freedman bound in four, five, and seven spacetime dimensions. The critical amplitude of the leading order perturbation, for which the perturbative expansion breaks down, increases as we consider less massive fields. We present various examples including a model with a self-interacting scalar field which is derived from a consistent truncation of IIB supergravity.
Time-periodic solutions of massive scalar fields in AdS background: perturbative constructions
Kim, Nakwoo
2014-01-01
We consider scalar fields which are coupled to Einstein gravity with a negative cosmological constant, and construct periodic solutions perturbatively. In particular, we study tachyonic scalar fields whose mass is at or above the Breitenlohner-Freedman bound in four, five, and seven spacetime dimensions. The critical amplitude of the leading order perturbation, for which the perturbative expansion breaks down, increases as we consider less massive fields. We present various examples including a model with a self-interacting scalar field which is derived from a consistent truncation of IIB supergravity.
Detection of the Long Period Long Duration (LPLD) Events in Time- and Frequency-Domain
Kwietniak, Anna
2015-02-01
Long Period Long Duration (LPLD) signals are unusual seismic events that can be observed during hydraulic fracturing. These events are very similar in appearance to tectonic tremors sequences, which were first observed in subduction zones. Their nature is not well known. LPLD might be related to the productivity of the reservoir. Different methods of the LPLD events' detection recorded during hydraulic fracturing are presented. The author applied two methods for LPLD detection-Butterworth filtering and Continuous Wavelet Transform (CWT). Additionally, a new approach to LPLD events detection-instantaneous seismic attributes-was used, common in a classical seismic interpretation but not in microseismic monitoring.
Steady-state time-periodic finite element analysis of a brushless DC motor drive considering motion
Directory of Open Access Journals (Sweden)
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.
Directory of Open Access Journals (Sweden)
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
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.
Space Radiation Cancer Risks and Uncertainities for Different Mission Time Periods
Kim,Myung-Hee Y.; Cucinotta, Francis A.
2012-01-01
Space radiation consists of solar particle events (SPEs), comprised largely of medium energy protons (less than several hundred MeV); and galactic cosmic ray (GCR), which includes high energy protons and high charge and energy (HZE) nuclei. For long duration missions, space radiation presents significant health risks including cancer mortality. Probabilistic risk assessment (PRA) is essential for radiation protection of crews on long term space missions outside of the protection of the Earth s magnetic field and for optimization of mission planning and costs. For the assessment of organ dosimetric quantities and cancer risks, the particle spectra at each critical body organs must be characterized. In implementing a PRA approach, a statistical model of SPE fluence was developed, because the individual SPE occurrences themselves are random in nature while the frequency distribution of SPEs depends strongly upon the phase within the solar activity cycle. Spectral variability of SPEs was also examined, because the detailed energy spectra of protons are important especially at high energy levels for assessing the cancer risk associated with energetic particles for large events. An overall cumulative probability of a GCR environment for a specified mission period was estimated for the temporal characterization of the GCR environment represented by the deceleration potential (theta). Finally, this probabilistic approach to space radiation cancer risk was coupled with a model of the radiobiological factors and uncertainties in projecting cancer risks. Probabilities of fatal cancer risk and 95% confidence intervals will be reported for various periods of space missions.
Periodic Solutions for a Semi-Ratio-Dependent Predator-Prey System with Delays on Time Scales
Directory of Open Access Journals (Sweden)
Xiaoquan Ding
2012-01-01
Full Text Available This paper is devoted to the existence of periodic solutions for a semi-ratio-dependent predator-prey system with time delays on time scales. With the help of a continuation theorem based on coincidence degree theory, we establish necessary and sufficient conditions for the existence of periodic solutions. Our results show that for the most monotonic prey growth such as the logistic, the Gilpin, and the Smith growth, and the most celebrated functional responses such as the Holling type, the sigmoidal type, the Ivlev type, the Monod-Haldane type, and the Beddington-DeAngelis type, the system always has at least one periodic solution. Some known results are shown to be special cases of the present paper.
Yasui, Takeshi; Hsieh, Yi-Da; Sakaguchi, Yoshiyuki; Hindle, Francis; Yokoyama, Shuko; Araki, Tsutomu; Hashimoto, Mamoru
2014-01-01
Fourier transform spectroscopy (FTS) has been widely used in a variety of fields in research, industry, and medicine due to its high signal-to-noise ratio, simultaneous acquisition of signals in a broad spectrum, and versatility for different radiation sources. Further improvement of the spectroscopic performance will widen its scope of applications. Here, we demonstrate improved spectral resolution by overcoming the time window limitation using discrete Fourier transform spectroscopy (dFTS) with precisely periodic pulsed terahertz (THz) radiation. Since infinitesimal resolution can be achieved at periodically discrete frequencies when the time window size is exactly matched to the repetition period T, a combination of THz-dFTS with a spectral interleaving technique achieves a spectral resolution only limited by the spectral interleaving interval. Linewidths narrower than 1/(50T) are fully resolved allowing the attribution of rotational-transition absorption lines of low-pressure molecular gases within a 1.25...
Directory of Open Access Journals (Sweden)
Ling Zhang
2012-01-01
Full Text Available We study a multi-period mean-variance portfolio selection problem with an uncertain time horizon and serial correlations. Firstly, we embed the nonseparable multi-period optimization problem into a separable quadratic optimization problem with uncertain exit time by employing the embedding technique of Li and Ng (2000. Then we convert the later into an optimization problem with deterministic exit time. Finally, using the dynamic programming approach, we explicitly derive the optimal strategy and the efficient frontier for the dynamic mean-variance optimization problem. A numerical example with AR(1 return process is also presented, which shows that both the uncertainty of exit time and the serial correlations of returns have significant impacts on the optimal strategy and the efficient frontier.
Existence of the time periodic solution for damped Schroedinger-Boussinesq equation
Institute of Scientific and Technical Information of China (English)
BolingGUO; XianyunDU
2000-01-01
In this paper, we study the time priodic solution for the weakly damped Schroedinger-Boussinesq equation, by Galerkin method, and prove the existence and uniqueness of the equations under some appropriate conditions.
30 CFR 250.1161 - When may I flare or vent gas for extended periods of time?
2010-07-01
... 30 Mineral Resources 2 2010-07-01 2010-07-01 false When may I flare or vent gas for extended... Production Requirements Flaring, Venting, and Burning Hydrocarbons § 250.1161 When may I flare or vent gas... flare or vent gas for an extended period of time. The Regional Supervisor will specify the...
Directory of Open Access Journals (Sweden)
Kwadwo S. Agyepong
2013-01-01
Full Text Available Time-course expression profiles and methods for spectrum analysis have been applied for detecting transcriptional periodicities, which are valuable patterns to unravel genes associated with cell cycle and circadian rhythm regulation. However, most of the proposed methods suffer from restrictions and large false positives to a certain extent. Additionally, in some experiments, arbitrarily irregular sampling times as well as the presence of high noise and small sample sizes make accurate detection a challenging task. A novel scheme for detecting periodicities in time-course expression data is proposed, in which a real-valued iterative adaptive approach (RIAA, originally proposed for signal processing, is applied for periodogram estimation. The inferred spectrum is then analyzed using Fisher’s hypothesis test. With a proper -value threshold, periodic genes can be detected. A periodic signal, two nonperiodic signals, and four sampling strategies were considered in the simulations, including both bursts and drops. In addition, two yeast real datasets were applied for validation. The simulations and real data analysis reveal that RIAA can perform competitively with the existing algorithms. The advantage of RIAA is manifested when the expression data are highly irregularly sampled, and when the number of cycles covered by the sampling time points is very reduced.
Pork meat matured for different periods of time in vacuum-packaging system
Directory of Open Access Journals (Sweden)
Marina Avena Tarsitano
2014-02-01
Full Text Available The objective of this study was to evaluate the quality of pork meat when matured. The treatments evaluated were: meat no maturated; meat matured for 3 days; meat matured for 6 days. The pH, water loss percentage, and liquid lost in thawing displayed a decreasing linear regression while the fluid lost in cooking showed an increasing linear regression. The L*, a*, b* and chroma showed an increasing linear effect while the tone displayed a decreasing linear regression. The mesophilic and psychrotrophic bacteria counts were greater for the treatments that underwent maturation. The shear force decrease linearly with the increase in the maturation period. The MFI, lipid oxidation, and sensory analyses were not affected by treatments. The maturation of the pork meat improved the color, reduced the pH and increased the tenderness. There was no change in the lipid stability of the meat, nor sensory damage.
Wierzcholski, Krzysztof
2014-01-01
The present paper is concerned with the calculation of the human hip joint parameters for periodic, stochastic unsteady, motion with asymmetric probability density function for gap height. The asymmetric density function indicates that the stochastic probabilities of gap height decreasing are different in comparison with the probabilities of the gap height increasing. The models of asymmetric density functions are considered on the grounds of experimental observations. Some methods are proposed for calculation of pressure distributions and load carrying capacities for unsteady stochastic conditions in a super thin layer of biological synovial fluid inside the slide biobearing gap limited by a spherical bone acetabulum. Numerical calculations are performed in Mathcad 12 Professional Program, by using the method of finite differences. This method assures stability of numerical solutions of partial differential equations and gives proper values of pressure and load carrying capacity forces occurring in human hip joints.
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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.
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
Lunar periodicity and the timing of river entry in Atlantic salmon Salmo salar.
Kuparinen, A; O'Hara, R B; Merilä, J
2009-07-01
Historical catch records of Atlantic salmon Salmo salar from three rivers discharging to the Baltic Sea in an area free from tides and from strong effects of the moon on illumination were analysed to investigate whether timing of S. salar river entry was associated with lunar cycles directly. Although a significant effect of lunar phase on river entry was detected, with more fish entering rivers around the full moon than other phases, the effect of the lunar cycle was very small compared with other sources of variation. Hence, the biological role of lunar cycle as a determinant of the timing of S. salar runs in the investigated populations was negligible, suggesting that lunar cycle per se does not play a role in the timing of S. salar river entry.
Gu, Yu; Tran, Trinh; Murase, Sachiko; Borrell, Andrew; Kirkwood, Alfredo; Quinlan, Elizabeth M
2016-10-05
Maturation of excitatory drive onto fast-spiking interneurons (FS INs) in the visual cortex has been implicated in the control of the timing of the critical period for ocular dominance plasticity. However, the mechanisms that regulate the strength of these synapses over cortical development are not understood. Here we use a mouse model to show that neuregulin (NRG) and the receptor tyrosine kinase erbB4 regulate the timing of the critical period. NRG1 enhanced the strength of excitatory synapses onto FS INs, which inhibited ocular dominance plasticity during the critical period but rescued plasticity in transgenics with hypoexcitable FS INs. Blocking the effects of endogenous neuregulin via inhibition of erbBs rescued ocular dominance plasticity in postcritical period adults, allowing recovery from amblyopia induced by chronic monocular deprivation. Thus, the strength of excitation onto FS INs is a key determinant of critical period plasticity and is maintained at high levels by NRG-erbB4 signaling to constrain plasticity in adulthood.
Kruger, A T; Wasserman, I M; Kruger, Adam T.; Loredo, Thomas J.; Wasserman, Ira
2002-01-01
We analyze the Time-Tagged Event (TTE) data from observations of gamma ray bursts (GRBs) and soft gamma repeaters (SGRs) by the Burst and Transient Source Experiment (BATSE). These data provide the best available time resolution for GRBs and SGRs. We have performed an extensive search for weak periodic signals in the frequency range 400 Hz to 2500 Hz using the burst records for 2203 GRBs and 152 SGR flares. The study employs the Rayleigh power as a test statistic to evaluate the evidence for periodic emissions. We find no evidence of periodic emissions from these events at these frequencies. In all but a very few cases the maximum power values obtained are consistent with what would be expected by chance from a non-periodic signal. In those few instances where there is marginal evidence for periodicity there are problems with the data that cast doubt on the reality of the signal. For classical GRBs, the largest Rayleigh power occurs in bursts whose TTE data appear to be corrupted. For SGRs, our largest Raylei...
Advantages and Drawbacks of Applying Periodic Time-Variant Modal Analysis to Spur Gear Dynamics
DEFF Research Database (Denmark)
Pedersen, Rune; Santos, Ilmar; Hede, Ivan Arthur
2010-01-01
A simplified torsional model with a reduced number of degrees-of-freedom is used in order to investigate the potential of the technique. A time-dependent gear mesh stiffness function is introduced and expanded in a Fourier series. The necessary number of Fourier terms is determined in order...
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.
Institute of Scientific and Technical Information of China (English)
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.
Directory of Open Access Journals (Sweden)
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
Directory of Open Access Journals (Sweden)
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.
Morena, Matthew A; Franke, John E
2012-01-01
Periodic environments may either enhance or suppress a population via resonant or attenuant cycles. We derive signature functions for predicting the responses of two competing populations to 2-periodic oscillations in six model parameters. Two of these parameters provide a non-trivial equilibrium and two provide the carrying capacities of each species in the absence of the other, but the remaining two are arbitrary and could be intrinsic growth rates. Each signature function is the sign of a weighted sum of the relative strengths of the oscillations of the perturbed parameters. Periodic environments are favourable for populations when the signature function is positive and are deleterious if the signature function is negative. We compute the signature functions of four classical, discrete-time two-species populations and determine regions in parameter space which are either favourable or detrimental to the populations. The six-parameter models include the Logistic, Ricker, Beverton-Holt, and Hassell models.
Jiang, Tian-Yu; Li, Li-Fang; Han, Zhan-Wen; Jiang, Deng-Kai
2010-04-01
The first complete charge-coupled device (CCD) light curves in B and V passbands of a neglected contact binary system, CW Cassiopeiae (CW Cas), are presented. They were analyzed simultaneously by using the Wilson and Devinney (WD) code (1971, ApJ, 166, 605). The photometric solution indicates that CW Cas is a W-type W UMa system with a mass ratio of m2/m1 2.234, and that it is in a marginal contact state with a contact degree of ˜6.5% and a relatively large temperature difference of ˜327K between its two components. Based on the minimum times collected from the literature, together with the new ones obtained in this study, the orbital period changes of CW Cas were investigated in detail. It was found that a periodical variation overlaps with a secular period decrease in its orbital period. The long-term period decrease with a rate of dP/dt = -3.44 × 10-8d yr-1 can be interpreted either by mass transfer from the more-massive component to the less-massive with a rate of dm2/dt = -3.6 × 10-8M⊙ yr-1, or by mass and angular-momentum losses through magnetic braking due to a magnetic stellar wind. A low-amplitude cyclic variation with a period of T = 63.7 yr might be caused by the light-time effect due to the presence of a third body.
Chaotic particle sedimentation in a rotating flow with time-periodic strength
Angilella, J R
2010-01-01
Particle sedimentation in the vicinity of a fixed horizontal vortex with time-dependent intensity can be chaotic, provided gravity is sufficient to displace the particle cloud while the vortex is off or weak. This "stretch, sediment and fold" mechanism is close to the so-called blinking vortex effect, which is responsible for chaotic transport of perfect tracers, except that in the present case the vortex motion is replaced by gravitational settling. In the present work this phenomenon is analyzed for heavy Stokes particles moving under the sole effect of gravity and of a linear drag. The vortex is taken to be a fixed isolated point vortex the intensity of which varies under the effect of either boundary conditions or volume force. When the unsteadiness of the vortex is weak and the free-fall velocity is of the order of the fluid velocity, and the particle response time is small, the particle motion equation can be written asymptotically as a perturbed hamiltonian system the phase portrait of which displays a...
Yan, Weixian
2017-01-01
The tunneling of the massless and massive Dirac particle through the strained barriers driven by the time-periodic scalar potentials and the static vector potentials is investigated, where the interrelationships among the strain, the incidence angle, the dynamic scalar potential, the magnetic field and the transmission of the Dirac particle have been discussed. In either massless or massive case, the intersection angle between the obliquely incident Dirac particle and strain determines the extent of deviation of the tunneling profiles from the strainless case. The time-periodic scalar potentials can enhance the capability of the Dirac particle to surmount the energy gap induced by the mass, reflecting quantum nature of the photon-assisted tunneling. When the magnetic field is switched on, the transmission overall presents a remarkably different profile, and decreases with the increase of the magnetic fields due to the conservation of the transverse momentum, which reduces the number of the side-band channels for tunneling.
Ferruzzo Correa, Diego P.; Bueno, Átila M.; Castilho Piqueira, José R.
2017-04-01
In this paper we investigate stability conditions for small-amplitude periodic solutions emerging near symmetry-preserving Hopf bifurcations in a time-delayed fully-connected N-node PLL network. The study of this type of systems which includes the time delay between connections has attracted much attention among researchers mainly because the delayed coupling between nodes emerges almost naturally in mathematical modeling in many areas of science such as neurobiology, population dynamics, physiology and engineering. In a previous work it has been shown that symmetry breaking and symmetry preserving Hopf bifurcations can emerge in the parameter space. We analyze the stability along branches of periodic solutions near fully-synchronized Hopf bifurcations in the fixed-point space, based on the reduction of the infinite-dimensional space onto a two-dimensional center manifold in normal form. Numerical results are also presented in order to confirm our analytical results.
Cai, Zuowei; Huang, Lihong; Guo, Zhenyuan; Chen, Xiaoyan
2012-09-01
This paper investigates the periodic dynamics of a general class of time-varying delayed neural networks with discontinuous right-hand sides. By employing the topological degree theory in set-valued analysis, differential inclusions theory and Lyapunov-like approach, we perform a thorough analysis of the existence, uniqueness and global exponential stability of the periodic solution for the neural networks. Especially, some sufficient conditions are derived to guarantee the existence, uniqueness and global exponential stability of the equilibrium point for the autonomous systems corresponding to the non-autonomous neural networks. Furthermore, the global convergence of the output and the convergence in finite time of the state are also discussed. Without assuming the boundedness or monotonicity of the discontinuous neuron activation functions, the obtained results improve and extend previous works on discontinuous or continuous neural network dynamical systems. Finally, two numerical examples are provided to show the applicability and effectiveness of our main results.
Duan, Lian; Huang, Lihong
2014-09-01
In this paper, we investigate a class of memristor-based neural networks with general mixed delays involving both time-varying delays and distributed delays. By using the Mawhin-like coincidence theorem, together with the differential inclusion theory, M-matrix properties and differential inequality techniques, some novel criteria are established for ensuring the periodicity and dissipativity for the addressed neural networks. Finally, two numerical examples with simulations are presented to demonstrate the effectiveness of the theoretical results.
Maintaining high precision of isotope ratio analysis over extended periods of time.
Brand, Willi A
2009-06-01
Stable isotope ratios are reliable and long lasting process tracers. In order to compare data from different locations or different sampling times at a high level of precision, a measurement strategy must include reliable traceability to an international stable isotope scale via a reference material (RM). Since these international RMs are available in low quantities only, we have developed our own analysis schemes involving laboratory working RM. In addition, quality assurance RMs are used to control the long-term performance of the delta-value assignments. The analysis schemes allow the construction of quality assurance performance charts over years of operation. In this contribution, the performance of three typical techniques established in IsoLab at the MPI-BGC in Jena is discussed. The techniques are (1) isotope ratio mass spectrometry with an elemental analyser for delta(15)N and delta(13)C analysis of bulk (organic) material, (2) high precision delta(13)C and delta(18)O analysis of CO(2) in clean-air samples, and (3) stable isotope analysis of water samples using a high-temperature reaction with carbon. In addition, reference strategies on a laser ablation system for high spatial resolution delta(13)C analysis in tree rings is exemplified briefly.
Energy Technology Data Exchange (ETDEWEB)
Kritzenberger, J.; Wokaun, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1997-06-01
Oxidation of CO over palladium/zirconia catalyst obtained from an amorphous Pd{sub 25}Zr{sub 75} precursor was investigated by time resolved FTIR spectroscopy. Sine wave shaped modulation of the reactant concentration, i.e. variation of CO or O{sub 2} partial pressure, was used to induce variations of the IR signals of product (CO{sub 2}) and unconverted reactant (CO), which were detected in a multi-pass absorption cell. The phase shift {phi} between external perturbation and variation of the CO{sub 2} signal was examined in dependence on temperature (100{sup o}C{<=}T{<=}350{sup o}C) and modulation frequency (1.39x10{sup -4}Hz{<=}{omega}{<=}6.67x10{sup -2}Hz). From the phase shift values, a simple Eley-Rideal mechanism is excluded, and the rate limiting step of the Langmuir-Hinshelwood mechanism for the CO oxidation may be identified. Adsorption and possible surface movement of CO to the actual reaction site determine the rate of the CO oxidation on the palladium/zirconia catalyst used in our study. The introduction of an external perturbation is a first step towards the application of two-dimensional infrared spectroscopy to heterogeneous catalyzed reactions. (author) 3 figs., 4 refs.
Identifying Thermally Challenging Landscapes and Time Periods for Wildlife Using Remote Sensing
Albright, T. P.; Pidgeon, A.; Radeloff, V.; Wardlow, B.
2011-12-01
Recent events and climate model outputs indicate an increase in the occurrence and magnitude of heat waves and other high temperature events in many locations. Temperatures at the land surface may be much higher than air temperatures making this a particularly relevant consideration for animals that nest, forage, or seek refuge at or near the ground. Often associated with heat waves are prolonged and/or rapid onset drought events, which can combine to place stress on vegetation and animals. In order to assess the influence of heat waves and drought on communities of birds, we developed statistical models between avian abundance and species richness data collected by volunteer observers as part of the North American Breeding Bird Survey and a suite of precipitation and temperature metrics. We used station data, gridded standardized precipitation indices, and remotely sensed vegetation indices, and developed an index of accumulated temperature exceedance using time series MODIS land surface temperature (LST) products. Mixed effects models accounting for nuisance factors and temporal autocorrelation revealed that LST was among the strongest predictors of same year and following-year avian abundance. In particular, declines in abundance were largest and most common among ground-nesting birds and long-distance migrants in the US Southwest. In cooler regions, high LST exceedances were sometimes associated with increases in abundance. Because these results do not indicate whether dispersal, reproductive effort, or mortality explain the changes, one area of current research focuses on identifying demographic mechanisms and population consequences of such responses. A second area of active research focuses on using LST data in conjunction with digital elevation models and derivatives and dense networks of ground-level observations to produce physiologically-relevant indicators of thermally stressful conditions for birds and other animals.
Ibrahim, Slim
2011-01-01
We investigate large time existence of solutions of the Navier-Stokes-Boussinesq equations with spatially almost periodic large data when the density stratification is sufficiently large. In 1996, Kimura and Herring \\cite{KH} examined numerical simulations to show a stabilizing effect due to the stratification. They observed scattered two-dimensional pancake-shaped vortex patches lying almost in the horizontal plane. Our result is a mathematical justification of the presence of such two-dimensional pancakes. To show the existence of solutions for large times, we use $\\ell^1$-norm of amplitudes. Existence for large times is then proven using techniques of fast singular oscillating limits and bootstrapping argument from a global-in-time unique solution of the system of limit equations.
Sinclair, Amber Hughes; Edgerton, Eric S; Wyzga, Ron; Tolsma, Dennis
2010-02-01
Concentrations of numerous ambient air pollutants have declined in recent years across the United States. Although it can be expected that reductions in air pollutants are associated with reductions in health effects, it is unclear whether this is actually the case. The purpose of this analysis was to compare the levels of and relationships between air pollutants and acute respiratory outpatient visits for two consecutive time periods totaling 53 mo. Air pollution data were collected at a centrally located monitor in Atlanta, GA, and include 24-hr averages of particulate matter (PM) less than 2.5 microm in aerodynamic diameter (PM2.5) and its components; coarse PM (PM10-2.5); PM less than 10 microm in aerodynamic diameter (PM10); oxygenated volatile organic compounds (OVOCs); 8-hr maximum ozone (O3); and 1-hr maximum nitrogen dioxide (NO2), carbon monoxide (CO), and sulfur dioxide (SO2). In addition, several metals and fractions of elemental carbon (EC) and organic carbon (OC) were investigated. Daily outpatient visit data were obtained from the electronic data warehouse of the Atlanta-based region of a nonprofit managed care organization. Poisson general linear modeling determined associations between daily levels of acute visits for four diagnosis groups (adult and child asthma, upper and lower respiratory infection) and air pollution measurements. Overall declining trends were observed in air pollutants and acute visits over the study period. Childhood asthma had the greatest number of significant associations with air pollutants, namely zinc and EC. The significant lag time between pollutant measurement and visit occurrence changed from 3-5 days in the first time period to 6-8 days in the later time period, but there was general consistency in several childhood asthma and pollutant associations over both time periods. The greatest evidence for a reduction in pollution being associated with an improvement in health response was for lower respiratory disease
Tary, J. B.; Herrera, R. H.; van der Baan, M.
2014-01-01
Recent studies show that the frequency content of continuous passive recordings contains useful information for the study of hydraulic fracturing experiments as well as longstanding applications in volcano and global seismology. The short-time Fourier transform (STFT) is usually used to obtain the time-frequency representation of a seismic trace. Yet, this transform has two main disadvantages, namely its fixed time-frequency resolution and spectral leakage. Here, we describe two methods based on autoregressive (AR) models: the short-time autoregressive method (ST-AR) and the Kalman smoother (KS). These two methods allow for the AR coefficients to vary over time in order to follow time-varying frequency contents. The outcome of AR methods depends mainly on the number of AR coefficients. We use a robust approach to estimate the optimum order of the AR methods that best matches the spectral comparison between Fourier and AR spectra. Comparing the outcomes of the three methods on a synthetic signal, a long-period volcanic event, and microseismic data, we show that the STFT and both AR methods are able to track fast changes in frequency content. The STFT provides reasonable results even for noisy data using a simple and effective algorithm. The coefficients of the AR filter are defined at all time in the case of the KS. However, its better time resolution is slightly offset by a lower frequency resolution and its computational complexity. The ST-AR has a high spectral resolution and the lowest sensitivity to background noises, facilitating the identification of the various frequency components. The estimated AR coefficients can also be used to extract parts of the signal. The study of long-term phenomena, such as resonance frequencies, or transient events, such as long-period events, could help to gain further insight on reservoir deformation during hydraulic fracturing experiments as well as global or volcano seismological signals.
Directory of Open Access Journals (Sweden)
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.
Zheng, Y; Escabí, M A
2013-08-01
Temporal sound cues are essential for sound recognition, pitch, rhythm, and timbre perception, yet how auditory neurons encode such cues is subject of ongoing debate. Rate coding theories propose that temporal sound features are represented by rate tuned modulation filters. However, overwhelming evidence also suggests that precise spike timing is an essential attribute of the neural code. Here we demonstrate that single neurons in the auditory midbrain employ a proportional code in which spike-timing precision and firing reliability covary with the sound envelope cues to provide an efficient representation of the stimulus. Spike-timing precision varied systematically with the timescale and shape of the sound envelope and yet was largely independent of the sound modulation frequency, a prominent cue for pitch. In contrast, spike-count reliability was strongly affected by the modulation frequency. Spike-timing precision extends from sub-millisecond for brief transient sounds up to tens of milliseconds for sounds with slow-varying envelope. Information theoretic analysis further confirms that spike-timing precision depends strongly on the sound envelope shape, while firing reliability was strongly affected by the sound modulation frequency. Both the information efficiency and total information were limited by the firing reliability and spike-timing precision in a manner that reflected the sound structure. This result supports a temporal coding strategy in the auditory midbrain where proportional changes in spike-timing precision and firing reliability can efficiently signal shape and periodicity temporal cues.
Twin peak quasi-periodic oscillations and the kinematics of orbital motion in a curved space-time
Germanà, Claudio
2012-01-01
Twin peak high frequency quasi-periodic oscillations (HF QPOs) observed in the power spectra of Low Mass X-ray Binaries (LMXBs), with either a black hole or a neutron star, have central frequencies that are typical of the orbital motion time-scale close to the compact object. Thus, twin HF QPOs might carry the fingerprint of physical effects in a strongly curved space-time. We study the azimuth phase \\phi(t) for orbital motion in the Schwarzschild metric and calculate the power spectra to check whether they display the features seen in the observed ones. We show that the timing of \\phi(t) on non-closed orbits can account for the observed twin peak HF QPOs. The uppermost couple of peaks in frequency has the lower peak that corresponds to the azimuthal frequency \
Crum, Matthew F; Trevaskis, Natalie L; Pouton, Colin W; Porter, Christopher J H
2017-02-06
The current studies sought to explore the impact of drug supersaturation and precipitation during the dispersion and digestion of lipid-based formulations (LBFs), on in vivo absorption using a coupled in vitro digestion-in vivo perfusion absorption model. Fenofibrate absorption was evaluated from a number of LBFs with different solubilization and supersaturation capacities, and conditions at the absorptive membrane manipulated by changing perfusion conditions, intestine segment lengths, and by the conduct of experiments in the presence or absence of suspended/precipitated drug. LBF dispersion and digestion resulted in varying periods of supersaturation across the different formulations. Even fleeting (5-10 min) periods of supersaturation were able to drive flux across a perfused 10 cm intestinal segment for up to 60 min, although over longer infusion periods (60-80 min) flux dropped in the absence of ongoing drug solubilization and supersaturation. In contrast, the presence or absence of precipitated/suspended drug, had little impact on drug flux. When perfused intestinal segment lengths were extended, the role of initial supersaturation was attenuated and ongoing solubilization conditions became the primary driver of absorptive flux. The data suggest that for highly permeable drugs such as fenofibrate, a short period of supersaturation at the absorptive membrane may be sufficient to drive absorptive drug flux in spite of significant drug precipitation on formulation dispersion or digestion in vitro. In contrast, where longer periods of absorption are required, for example, at higher doses, the requirement for ongoing solubilization and supersaturation becomes more apparent.
Maruddani, Di Asih I.; Rosadi, Dedi; Gunardic, Abdurakhman
2015-02-01
The value of a corporate bond is conventionally expressed in terms of zero coupon bond. In practice, the most common form of debt instrument is coupon bond and allows early default before maturity as safety covenant for the bondholder. This paper study valuation for one period coupon bond, a coupon bond that only give one time coupon at the bond period. It assumes that the model give bondholder the right to reorganize a firm if its value falls below a given barrier. Revised first passage time approach is applied for default time rule. As a result, formulas of equity, liability, and probability of default is derived for this specified model. Straightforward integration under risk neutral pricing is used for deriving those formulas. For the application, bond of Bank Rakyat Indonesia (BRI) as one of the largest bank in Indonesia is analyzed. R computing show that value of the equity is IDR 453.724.549.000.000, the liability is IDR 2.657.394.000.000, and the probability if default is 5.645305E-47 %.
Directory of Open Access Journals (Sweden)
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.
DEFF Research Database (Denmark)
Allen, Matthew S.; Sracic, Michael W.; Chauhan, Shashank;
2011-01-01
in the velocity of the wind with height and changes in the aerodynamics of the blades as they pass the tower. These effects may cause parametric resonance or other unexpected phenomena, so it is important to properly characterize them so that these machines can be designed to achieve high reliability, 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...
Directory of Open Access Journals (Sweden)
Hala A. Fergany
2005-01-01
Full Text Available 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 variables by using the geometric programming approach. A special case is deduced and an illustrative numerical example is added.
Hoffmann, Dirk L.; Rogerson, Mike; Spötl, Christoph; Luetscher, Marc; Vance, Derek; Osborne, Anne H.; Fello, Nuri M.; Moseley, Gina E.
2016-11-01
We present the first speleothem-derived central North Africa rainfall record for the last glacial period. The record reveals three main wet periods at 65-61 ka, 52.5-50.5 ka and 37.5-33 ka that lead obliquity maxima and precession minima. We find additional minor wet episodes that are synchronous with Greenland interstadials. Our results demonstrate that sub-tropical hydrology is forced by both orbital cyclicity and North Atlantic moisture sources. The record shows that after the end of a Saharan wet phase around 70 ka ago, North Africa continued to intermittently receive substantially more rainfall than today, resulting in favourable environmental conditions for modern human expansion. The encounter and subsequent mixture of Neanderthals and modern humans – which, on genetic evidence, is considered to have occurred between 60 and 50 ka – occurred synchronously with the wet phase between 52.5 and 50.5 ka. Based on genetic evidence the dispersal of modern humans into Eurasia started less than 55 ka ago. This may have been initiated by dry conditions that prevailed in North Africa after 50.5 ka. The timing of a migration reversal of modern humans from Eurasia into North Africa is suggested to be coincident with the wet period between 37.5 and 33 ka.
The nighttime F-region climatology during magnetically quiet periods seen from TIMED/GUVI and DMSP
Kil, H.; Paxton, L.; Zhang, Y.; Wolven, B.; Morrison, D.
2004-12-01
In this study, we investigate the drivers of the nighttime climatology in the low- and middle-latitude ionosphere during quiet periods using the TIMED/GUVI and DMSP data. The observation results show that the seasonal hemispheric asymmetry in plasma density is primary induced by the summer-to-winter wind circulations while the longitudinal variations of the F-region morphology is produced by the contribution of the zonal winds that depends on the magnetic declination. However, the F-region morphology observed at 625 km from TIMED/GUVI does not precisely conform the morphology observed at 840 km from DMSP. We will discuss the differential neutral wind effect on the F-region morphology depending on the magnetic declination, altitude, and the location of the geomagnetic equator relative to the geographic equator.
Roach, Gregory D; Sargent, Charli; Darwent, David; Dawson, Drew
2012-03-01
Most of the research related to human fatigue in the aviation industry has focussed on long-haul pilots, but short-haul pilots also experience elevated levels of fatigue. The aim of this study was to examine the impact of early start times on the amount of sleep obtained prior to duty and on fatigue levels at the start of duty. Seventy short-haul pilots collected data regarding their duty schedule and sleep/wake behaviour for at least two weeks. Data were collected using self-report duty/sleep diaries and wrist activity monitors. Mixed-effects regression analyses were used to examine the effects of duty start time (04:00-10:00 h) on (i) the total amount of sleep obtained in the 12h prior to the start of duty and (ii) self-rated fatigue level at the start of duty. Both analyses indicated significant main effects of duty start time. In particular, the amount of sleep obtained in the 12h prior to duty was lowest for duty periods that commenced between 04:00 and 05:00 h (i.e. 5.4h), and greatest for duty periods that commenced between 09:00 and 10:00 h (i.e. 6.6h). These data indicate that approximately 15 min of sleep is lost for every hour that the start of duty is advanced prior to 09:00 h. In addition, self-rated fatigue at the start of duty was highest for duty periods that commenced between 04:00 and 05:00 h, and lowest for duty periods that commenced between 09:00 and 10:00 h. Airlines should implement a fatigue risk management system (FRMS) for short-haul pilots required to work early-morning shifts. One component of the FRMS should be focussed on the production of 'fatigue-friendly' rosters. A second component of the FRMS should be focussed on training pilots to optimise sleep opportunities, to identify circumstances where the likelihood of fatigue is elevated, and to manage the risks associated with fatigue-related impairment.
Twenge, Jean M; Carter, Nathan T; Campbell, W Keith
2016-12-08
Orth, Trzesniewski, and Robins (2010) concluded that the nationally representative Americans' Changing Lives (ACL) cohort-sequential study demonstrated moderate to large age differences in self-esteem, and no birth cohort (generational) differences in the age trajectory. In a reanalysis of these data using 2 different statistical techniques, we find significant increases in self-esteem that could be attributed to birth cohort or time period. First, hierarchical linear modeling analyses with birth cohort as a continuous variable (vs. the multiple group formulation used by Orth et al.) find that birth cohort has a measurable influence on self-esteem through its interaction with age. Participants born in later years (e.g., 1960) were higher in self-esteem and were more likely to increase in self-esteem as they aged than participants born in earlier years (e.g., 1920). However, the estimated age trajectory up to age 60 is similar in Orth et al.'s results and in the results from our analyses including cohort. Second, comparing ACL respondents of the same age in 1986 versus 2002 (a time-lag design) yields significant birth cohort differences in self-esteem, with 2002 participants of the same age higher in self-esteem than those in 1986. Combined with some previous studies finding significant increases in self-esteem and positive self-views over time, these results suggest that cultural change in the form of cohort and time period cannot be ignored as influences in cross-sectional and longitudinal studies. (PsycINFO Database Record
Nam, Kwangho
2014-10-14
Development of multiscale ab initio quantum mechanical and molecular mechanical (AI-QM/MM) method for periodic boundary molecular dynamics (MD) simulations and their acceleration by multiple time step approach are described. The developed method achieves accuracy and efficiency by integrating the AI-QM/MM level of theory and the previously developed semiempirical (SE) QM/MM-Ewald sum method [J. Chem. Theory Comput. 2005, 1, 2] extended to the smooth particle-mesh Ewald (PME) summation method. In the developed methods, the total energy of the simulated system is evaluated at the SE-QM/MM-PME level of theory to include long-range QM/MM electrostatic interactions, which is then corrected on the fly using the AI-QM/MM level of theory within the real space cutoff. The resulting energy expression enables decomposition of total forces applied to each atom into forces determined at the low-level SE-QM/MM method and correction forces at the AI-QM/MM level, to integrate the system using the reversible reference system propagator algorithm. The resulting method achieves a substantial speed-up of the entire calculation by minimizing the number of time-consuming energy and gradient evaluations at the AI-QM/MM level. Test calculations show that the developed multiple time step AI-QM/MM method yields MD trajectories and potential of mean force profiles comparable to single time step QM/MM results. The developed method, together with message passing interface (MPI) parallelization, accelerates the present AI-QM/MM MD simulations about 30-fold relative to the speed of single-core AI-QM/MM simulations for the molecular systems tested in the present work, making the method less than one order slower than the SE-QM/MM methods under periodic boundary conditions.
Parra, M. A.; Santiago, J. L.; Martín, F.; Martilli, A.; Santamaría, J. M.
2010-06-01
The representativeness of point measurements in urban areas is limited due to the strong heterogeneity of the atmospheric flows in cities. To get information on air quality in the gaps between measurement points, and have a 3D field of pollutant concentration, Computational Fluid Dynamic (CFD) models can be used. However, unsteady simulations during time periods of the order of months, often required for regulatory purposes, are not possible for computational reasons. The main objective of this study is to develop a methodology to evaluate the air quality in a real urban area during large time periods by means of steady CFD simulations. One steady simulation for each inlet wind direction was performed and factors like the number of cars inside each street, the length of streets and the wind speed and direction were taken into account to compute the pollutant concentration. This approach is only valid in winter time when the pollutant concentrations are less affected by atmospheric chemistry. A model based on the steady-state Reynolds-Averaged Navier-Stokes equations (RANS) and standard k-ɛ turbulence model was used to simulate a set of 16 different inlet wind directions over a real urban area (downtown Pamplona, Spain). The temporal series of NO x and PM 10 and the spatial differences in pollutant concentration of NO 2 and BTEX obtained were in agreement with experimental data. Inside urban canopy, an important influence of urban boundary layer dynamics on the pollutant concentration patterns was observed. Large concentration differences between different zones of the same square were found. This showed that concentration levels measured by an automatic monitoring station depend on its location in the street or square, and a modelling methodology like this is useful to complement the experimental information. On the other hand, this methodology can also be applied to evaluate abatement strategies by redistributing traffic emissions.
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.
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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.
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Kramer, P [Theoretische Physik, University Tuebingen (Germany); Kramer, T [Institute for Theoretical Physics, University Regensburg (Germany); Man' ko, V I [Lebedev Physical Institute, Moscow (Russian Federation)], E-mail: peter.kramer@uni-tuebingen.de
2009-05-15
We consider classical and quantum propagators for two different time intervals. If these propagators follow one another in a Fibonacci sequence we get a discrete quasi-periodic system. A theorem due to Nielsen provides a novel conserved quantity for this system. The Nielsen quantity controls the transition between commutative and non-commutative propagation in time. The quasi-periodically kicked oscillator, moreover, is dominated by quasi-periodic analogues of the Floquet theorem.
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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.
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 ...
TIME DELAYS IN QUASI-PERIODIC PULSATIONS OBSERVED DURING THE X2.2 SOLAR FLARE ON 2011 FEBRUARY 15
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Dolla, L.; Marque, C.; Seaton, D. B.; Dominique, M.; Berghmans, D.; Cabanas, C.; De Groof, A.; Verdini, A.; West, M. J.; Zhukov, A. N. [Solar-Terrestrial Center of Excellence, Royal Observatory of Belgium, Avenue Circulaire 3, B-1180 Brussels (Belgium); Van Doorsselaere, T. [Centrum voor Plasma-Astrofysica, Department of Mathematics, KULeuven, Celestijnenlaan 200B bus 2400, B-3001 Leuven (Belgium); Schmutz, W. [Physikalisch-Meteorologisches Observatorium Davos, World Radiation Center, Davos Dorf (Switzerland); Zender, J., E-mail: dolla@sidc.be [European Space Agency, ESTEC, Keplerlaan 1, 2201 AZ Noordwijk (Netherlands)
2012-04-10
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 timescale 1-30 s and find different time lags between different wavebands. During the impulsive phase, the Reuven Ramaty High Energy Solar Spectroscopic Imager 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-ultraviolet (EUV) channels of the Euv SpectroPhotometer (ESP) on board the Solar Dynamic Observatory. The zirconium and aluminum filter channels of the Large Yield Radiometer on board the Project for On-Board Autonomy satellite and the soft X-ray (SXR) channel of ESP follow. The largest lags occur in observations from the Geostationary Operational Environmental Satellite, where the channel at 1-8 A leads the 0.5-4 A channel by several seconds. The time lags between the first and last channels is up to Almost-Equal-To 9 s. We identified at least two distinct time intervals during the flare impulsive phase, during which the QPPs were associated with two different sources in the Nobeyama RadioHeliograph at 17 GHz. The radio as well as the hard X-ray channels showed different lags during these two intervals. To our knowledge, this is the first time that time lags are reported between EUV and SXR fluctuations on these timescales. We discuss possible emission mechanisms and interpretations, including flare electron trapping.
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Amit kumar Mishra
2015-01-01
Full Text Available In this paper, we have analyzed the effect of time periodic temperature modulation on convective stability in anisotropic porous cavity. The cavity is heated from below and cooled from above. A weakly non-linear stability analysis is done to find Nusselt number governing the heat transport. The infinitely small disturbances are expanded in terms of power series of amplitude of modulation. Analytically the nonautonomous Ginzburg- landau amplitude equation is obtained for the stationary mode of convection. The effects of various parameters like Vadasz number, mechanical and thermal anisotropic parameters, amplitude of oscillations, frequency of modulation and aspect ratio of the cavity on heat transport is studied and plotted graphically. It is observed that the heat transport can also be controlled by suitably adjusting the external and internal parameters of the system.
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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.
Institute of Scientific and Technical Information of China (English)
周利; 郑严; 相建海
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.
Institute of Scientific and Technical Information of China (English)
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.
Chen, Weisheng; Li, Wei; Miao, Qiguang
2010-07-01
An adaptive backstepping tracking scheme is developed for a class of strict-feedback systems with unknown periodically time-varying parameters and unknown control gain functions. High-order neural network (HONN) and Fourier series expansion (FSE) are combined into a new function approximator to model each uncertain term in the system. The dynamic surface control (DSC) approach is used to solve the problem of 'explosion of complexity' in the backstepping design procedure. Nussbaum gain function (NGF) is employed to deal with the unknown control gain functions. The uniform boundedness of all closed-loop signals is guaranteed. The tracking error is proved to converge to a small residual set around the origin. Two simulation examples are provided to demonstrate the effectiveness of the control scheme designed in this paper.
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Naglaa H. El-Sodany
2011-01-01
Full Text Available 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/Recommendations: We can obtain the optimal values of these policy variables by using the geometric programming approach. A special case is deduced and an illustrative numerical example is added.
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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.
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Daniel Gachuiri Njau
2016-09-01
Full Text Available Frequently, forensic entomology is applied in the use of insect maggots for the identification of specimens or remains of humans. Maggot crop analysis could be valuable in criminal investigations when maggots are found at a crime scene and a corpse is absent. Human short tandem repeat (STR has previously been used to support the association of maggots to a specific corpse but not in the period at which the body has been decomposing. The aim of this research was to assess the time period for successful STR analyses of human DNA from third instar maggots (Protophormia terraenovae obtained from decomposing human corpses as well as to investigate the human DNA turnover and degradation in the maggot crop after they are removed from food and/or are fed on a beef (a new/different food source. Results showed that the amount of human DNA recovered from maggots decreased with time in all cases. For maggots fed on beef, the human DNA could only be recovered up to day two and up to day four for the starved maggots. STR analyses of human DNA from maggots’ crop content using 16 loci generated profiles that matched those of reference samples although some of the alleles were not amplifiable therefore generating partial profiles for the samples starved for 4 days and those fed on beef. This may be due to nuclease activity present in the gut of larvae that may have caused degradation of DNA and consequently reduction in DNA yield. It was possible to identify the decomposing body using STRs as markers.
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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.
Espinar, B.; Blanc, P.; Wald, L.; Hoyer-Klick, C.; Schroedter-Homscheidt, M.; Wanderer, T.
2012-04-01
Meteorological data measured by ground stations are often a key element in the development and validation of methods exploiting satellite images. These data are considered as a reference against which satellite-derived estimates are compared. Long-term radiation and meteorological measurements are available from a large number of measuring stations. However, close examination of the data often reveals a lack of quality, often for extended periods of time. This lack of quality has been the reason, in many cases, of the rejection of large amount of available data. The quality data must be checked before their use in order to guarantee the inputs for the methods used in modelling, monitoring, forecast, etc. To control their quality, data should be submitted to several conditions or tests. After this checking, data that are not flagged by any of the test is released as a plausible data. In this work, it has been performed a bibliographical research of quality control tests for the common meteorological variables (ambient temperature, relative humidity and wind speed) and for the usual solar radiometrical variables (horizontal global and diffuse components of the solar radiation and the beam normal component). The different tests have been grouped according to the variable and the average time period (sub-hourly, hourly, daily and monthly averages). The quality test may be classified as follows: • Range checks: test that verify values are within a specific range. There are two types of range checks, those based on extrema and those based on rare observations. • Step check: test aimed at detecting unrealistic jumps or stagnation in the time series. • Consistency checks: test that verify the relationship between two or more time series. The gathered quality tests are applicable for all latitudes as they have not been optimized regionally nor seasonably with the aim of being generic. They have been applied to ground measurements in several geographic locations, what
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Mohanty Paritosh
2011-01-01
Full Text Available Abstract We report the first synthesis of periodic mesoporous silicas templated by bicelles. The obtained materials form novel pillared lamellar structures with a high degree of periodic order, narrow pore size distributions, and exceptionally high surface areas.
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.
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Sjoegren, J.-U.; Andersson, S.; Olofsson, T. [Department of Applied Physics and Electronics, Umeaa University, SE-901 87 Umeaa (Sweden)
2009-07-15
In order to identify buildings that have energy saving potential there is a need for further development of robust methods for evaluation of energy performance as well as reliable key energy indicators. To be able to evaluate a large database of buildings, the evaluation has to be founded on available data, since an in-depth analysis of each building would require large measurement efforts in terms of both parameters and time. In practice, data are usually available for consumed energy, water, and so on, namely consumption that the tenants or property holder has to pay for. In order to evaluate the energy saving potential and energy management, interesting key energy indicators are the total heat loss coefficient K{sub tot} (W/K), the indoor temperature (T{sub i}), and the utilisation of the available heat (solar radiation and electricity primarily used for purposes other than heating). The total heat loss coefficient, K{sub tot}, is a measure of the heat lost through the building's envelope, whereas T{sub i} and the gained energy reflect the user's behaviour and efficiency of the control system. In this study, a linear regression approach (energy signature) has been used to analyse data for 2003-2006 for nine fairly new multifamily buildings located in the Stockholm area, Sweden. The buildings are heated by district heating and the electricity used is for household equipment and the buildings' technical systems. The data consist of monthly energy used for heating and outdoor temperature together with annual water use, and for some buildings data for household electricity are also available. For domestic hot water and electricity, monthly distributions have been assumed based on data from previous studies and energy companies. The impact on K{sub tot} and T{sub i} of the time period and assumed values for the utilised energy are investigated. The results show that the obtained value of K{sub tot} is rather insensitive to the time period and utilised
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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.
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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.
Institute of Scientific and Technical Information of China (English)
Desheng TIAN
2008-01-01
The author considers a three-species ratio-dependent predator-prey model with time delay in a two-patch environments. This model is of periodic coefficients, which incorporates the periodicity of the environment. By means of the coincidence degree theory, sufficient conditions for the existence of at least one positive periodic solution of this model are established. Moreover, The author shows that the system is uniformly persistent under the conditions.
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Christina Murphey
2017-01-01
Full Text Available Psychological distress, defined as depression, anxiety, and insomnia in this study, can occur following the birth of a baby as new mothers, in addition to marked physiological changes, are faced with adapting to new roles and responsibilities. We investigated the cooccurrence of stress, depression, anxiety, and insomnia in mothers during the postpartum period; tested the feasibility of study methods and procedures for use in this population; and identified new mothers interest in using cranial electrotherapy stimulation (CES as an intervention for reducing psychological distress. We recruited healthy, low-risk, English speaking first-time mothers, ages 18–32 years, with healthy babies (N=33, within 12 months of an uncomplicated birth. Participants completed the PSS, HAM-D14, HAM-A17, and PSQI19. No problems were encountered with study procedures. Mothers reported a high interest (4.9 in the potential use of CES to treat or prevent the occurrence of psychological distress. All participants (N=33 reported moderate levels of depression and anxiety, while 75.8% (n=25 reported insomnia. PSS scores were within the norms for healthy women. Further research is recommended to investigate if our findings can be replicated or if different patterns of associations emerge. Implications for clinical practice are addressed.
Carter, Patricia; Price, Larry R.; Champion, Jane Dimmitt; Nichols, Francine
2017-01-01
Psychological distress, defined as depression, anxiety, and insomnia in this study, can occur following the birth of a baby as new mothers, in addition to marked physiological changes, are faced with adapting to new roles and responsibilities. We investigated the cooccurrence of stress, depression, anxiety, and insomnia in mothers during the postpartum period; tested the feasibility of study methods and procedures for use in this population; and identified new mothers interest in using cranial electrotherapy stimulation (CES) as an intervention for reducing psychological distress. We recruited healthy, low-risk, English speaking first-time mothers, ages 18–32 years, with healthy babies (N = 33), within 12 months of an uncomplicated birth. Participants completed the PSS, HAM-D14, HAM-A17, and PSQI19. No problems were encountered with study procedures. Mothers reported a high interest (4.9) in the potential use of CES to treat or prevent the occurrence of psychological distress. All participants (N = 33) reported moderate levels of depression and anxiety, while 75.8% (n = 25) reported insomnia. PSS scores were within the norms for healthy women. Further research is recommended to investigate if our findings can be replicated or if different patterns of associations emerge. Implications for clinical practice are addressed. PMID:28191350
Institute of Scientific and Technical Information of China (English)
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
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…
Nagesh, Deepthi; Ghosh, Shayani
2017-02-11
Forensic Science is the application of science to the criminal and civil laws that are enforced by police agencies in a criminal justice system. It is a science which relies on physical evidence; one of the important physical evidences being blood. The purpose of this research was to determine the efficacy of luminol reagent in detecting bloodstains on different surfaces, concealed by multiple layers of paint, over a period of time and also to compare the intensities of chemiluminescence exhibited by them. In this study, dry wall, wooden planks and metal surfaces were identified as commonly encountered surfaces at crime scenes and hence 25 of each surface were simulated and blood was spattered, which were then concealed by progressive layers of paint specific to each surface. Thereafter, each surface was critically observed for the intensity of chemiluminescence, following the application of luminol and the results were documented as photographs. The research was conducted for duration of 50 days, in order to study the effect of ageing of concealment upon detection of bloodstains using luminol. Varying intensities of chemiluminescence were displayed by all the three simulated surfaces deposited with paint over bloodstains up to three layers of concealment, depending on the nature of the surface which were captured using photography. The highest intensity of chemiluminescence was shown by concealed bloodstains on dry wall and metal surfaces, despite the number of layers of concealment. However, an increase in the number of layers of concealment produced a significant decrease in the intensity of chemiluminescenece displayed by the bloodstains concealed by paint upon reacting with luminol on metal sheets, which was not found to be uniform and consistent on the other surfaces. These findings highlight the fact that bloodstains concealed by paint could be effectively detected by luminol reagent, despite the nature and ageing of concealment and thereby provide a lead to
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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
Rakkiyappan, R; Sivaranjani, R; Velmurugan, G; Cao, Jinde
2016-05-01
In this paper, the problem of the global O(t(-α)) stability and global asymptotic periodicity for a class of fractional-order complex-valued neural networks (FCVNNs) with time varying delays is investigated. By constructing suitable Lyapunov functionals and a Leibniz rule for fractional differentiation, some new sufficient conditions are established to ensure that the addressed FCVNNs are globally O(t(-α)) stable. Moreover, some sufficient conditions for the global asymptotic periodicity of the addressed FCVNNs with time varying delays are derived, showing that all solutions converge to the same periodic function. Finally, numerical examples are given to demonstrate the effectiveness and usefulness of our theoretical results.
Energy Technology Data Exchange (ETDEWEB)
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.
DEFF Research Database (Denmark)
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...
Directory of Open Access Journals (Sweden)
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
Directory of Open Access Journals (Sweden)
Michael P Anastario
Full Text Available Following the declaration that President Mwai Kibaki was the winner of the Kenyan presidential election held on December 27, 2007, a period of post-election violence (PEV took place. In this study, we aimed to identify whether the period of PEV in Kenya was associated with systematic changes in sexual assault case characteristics.Medical records of 1,615 patients diagnosed with sexual assault between 2007 and 2011 at healthcare facilities in Eldoret (n = 569, Naivasha (n = 534, and Nakuru (n = 512 were retrospectively reviewed to examine characteristics of sexual assault cases over time. Time series and linear regression were used to examine temporal variation in case characteristics relative to the period of post-election violence in Kenya. Key informant interviews with healthcare workers at the sites were employed to triangulate findings. The time series of sexual assault case characteristics at these facilities were examined, with a specific focus on the December 2007-February 2008 period of post-election violence. Prais-Winsten estimates indicated that the three-month period of post-election violence was associated with a 22 percentage-point increase in cases where survivors did not know the perpetrator, a 20 percentage-point increase in cases with more than one perpetrator, and a 4 percentage-point increase in cases that had evidence of abdominal injury. The post-election violence period was also associated with an 18 percentage-point increase in survivors waiting >1 month to report to a healthcare facility. Sensitivity analyses confirmed that these characteristics were specific to the post-election violence time period.These results demonstrate systematic patterns in sexual assault characteristics during the PEV period in Kenya.
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...
Ratnaningrum, Diah; Endah, Een Sri; Pudjiraharti, Sri
2017-01-01
Research on extraction method of emprit ginger using ethanol with agitation of 100 rpm at different temperatures (ambient temperature, 40, and 50°C) and various extraction period of times (30, 60, and 90 minutes) was conducted. Analysis of chemicals content i.e. total phenolic and total flavonoid. The objective of this work was to study the effect of temperatures and extraction period of times on the chemicals content of its ethanol extract. Based on the results of the test, the highest content total flavonoid (5.17% w/w) was resulted at 40°C for 90 minutes, while the total phenolic content was not affected by either temperature or extraction period of times used. The content of total phenolic was around 2.39% to 2.65% w/w.
Liu, Huiyu; Xu, Xiaojuan; Lin, Zhenshan; Zhang, Mingyang; Mi, Ying; Huang, Changchun; Yang, Hao
2016-12-01
With the ensemble Empirical Mode Decomposition Method (EEMD) and the non-parametric Mann-Kendall Test, the quasi-periodic and abrupt changes of sedimentation rate at multiple time scales, and their relations to climate changes and human activities from 1951 to 2010 in Meiliang Bay of Lake Taihu (China) were studied. The results showed the following. (1) The change in sedimentation rate can be completely decomposed into three quasi-periodic changes on 3.7, 6.4, and 24-yr time scales, and a long-term trend. (2) The quasi-periodic changes in sedimentation rate are significantly and positively related to changes in annual average temperature at 6.4 and 24-yr time scales and human activities at 3.7-yr time scales, and not significantly related to precipitation at these time scales. The trend of sedimentation rate has a negative relation with temperature, but positive relations with precipitation and human activities. As a whole, the total variance contribution of climate changes to the quasi-periodic changes of sedimentation rate is close to that of human activities; (3) Temperature and precipitation are possibly related to the abrupt change of sedimentation rate as a whole. Floods have significant impacts on abrupt changes in the sedimentation rate at 3.7, 6.4 and 24-yr time scales. Moreover, some abrupt changes of sedimentation rate at 3.7- and 6.4-yr time scales are partly related to the changes of precipitation at 3.1-yr time scale and temperature at 5-yr time scale. The results of this study will help identify the impacts of climate change and human activities on lake sedimentation at different time scales, and will be available for use as a guide for reasonable development and effective protection of lake resources.
Ludwig, Alon; Leviatan, Yehuda
2008-02-01
We introduce a time-domain source-model technique for analysis of two-dimensional, transverse-magnetic, plane-wave scattering by a photonic crystal slab composed of a finite number of identical layers, each comprising a linear periodic array of dielectric cylinders. The proposed technique takes advantage of the periodicity of the slab by solving the problem within a unit cell of the periodic structure. A spectral analysis of the temporal behavior of the fields scattered by the slab shows a clear agreement between frequency bands where the spectral density of the transmitted energy is low and the bandgaps of the corresponding two-dimensionally infinite periodic structure. The effect of the bandwidth of the incident pulse and its center frequency on the manner it is transmitted through and reflected by the slab is studied via numerical examples.
Nitsche, Ludwig C.; Nitsche, Johannes M.; Brenner, Howard
1988-01-01
The sedimentation and diffusion of a nonneutrally buoyant Brownian particle in vertical fluid-filled cylinder of finite length which is instantaneously inverted at regular intervals are investigated analytically. A one-dimensional convective-diffusive equation is derived to describe the temporal and spatial evolution of the probability density; a periodicity condition is formulated; the applicability of Fredholm theory is established; and the parameter-space regions are determined within which the existence and uniqueness of solutions are guaranteed. Numerical results for sample problems are presented graphically and briefly characterized.
Yadav, Pankaj; Choudhury, Deepak; Sadanandappa, Madhumala K; Sharma, Vijay Kumar
2015-08-01
Circadian clocks time developmental stages of fruit flies Drosophila melanogaster, while light/dark (LD) cycles delimit emergence of adults, conceding only during the "allowed gate." Previous studies have revealed that time-to-emergence can be altered by mutations in the core clock gene period (per), or by altering the length of LD cycles. Since this evidence came from studies on genetically manipulated flies, or on flies maintained under LD cycles with limited range of periods, inferences that can be drawn are limited. Moreover, the extent of shortening or lengthening of time-to-emergence remains yet unknown. In order to pursue this further, we assayed time-to-emergence of D. melanogaster under 12 different LD cycles as well as in constant light (LL) and constant dark conditions (DD). Time-to-emergence in flies occurred earlier under LL than in LD cycles and DD. Among the LD cycles, time-to-emergence occurred earlier under T4-T8, followed by T36-T48, and then T12-T32, suggesting that egg-to-emergence duration in flies becomes shorter when the length of LD cycles deviates from 24 h, bearing a strong positive and a marginally negative correlation with day length, for values shorter and longer than 24 h, respectively. These results suggest that the extent of mismatch between the period of circadian clocks and environmental cycles determines the time-to-emergence in Drosophila.
Kafka, K R P; Austin, D R; Li, H; Yi, A Y; Cheng, J; Chowdhury, E A
2015-07-27
Time-resolved diffraction microscopy technique has been used to observe the formation of laser-induced periodic surface structures (LIPSS) from the interaction of a single femtosecond laser pulse (pump) with a nano-scale groove mechanically formed on a single-crystal Cu substrate. The interaction dynamics (0-1200 ps) was captured by diffracting a time-delayed, frequency-doubled pulse (probe) from nascent LIPSS formation induced by the pump with an infinity-conjugate microscopy setup. The LIPSS ripples are observed to form asynchronously, with the first one forming after 50 ps and others forming sequentially outward from the groove edge at larger time delays. A 1-D analytical model of electron heating including both the laser pulse and surface plasmon polariton excitation at the groove edge predicts ripple period, melt spot diameter, and qualitatively explains the asynchronous time-evolution of LIPSS formation.
Wei, Hsien-Hung; Halpern, David; Grotberg, James B
2005-05-15
This paper analyzes the effect of surfactant on the linear stability of an annular film in a capillary undergoing a time-periodic pressure gradient force. The annular film is thin compared to the radius of the tube. An asymptotic analysis yields a coupled set of equations with time-periodic coefficients for the perturbed fluid-fluid interface and the interfacial surfactant concentration. Wei and Rumschitzki (submitted for publication) previously showed that the interaction between a surfactant and a steady base flow could induce a more severe instability than a stationary base state. The present work demonstrates that time-periodic base flows can modify the features of the steady-flow-based instability, depending on surface tension, surfactant activity, and oscillatory frequency. For an oscillatory base flow (with zero mean), the growth rate decreases monotonically as the frequency increases. In the low-frequency limit, the growth rate approaches a maximum corresponding to the growth rate of a steady base flow having the same amplitude. In the high-frequency limit, the growth rate reaches a minimum corresponding to the growth rate in the limit of a stationary base state. The underlying mechanisms are explained in detail, and extension to other time-periodic forms is further exploited.
Energy Technology Data Exchange (ETDEWEB)
Bostan, M. [Institut National de Recherche en Informatique et en Automatique (INRIA), 06 - Sophia-Antipolis (France)
2001-02-01
The topic of this paper is the numerical analysis of time periodic solution for electromagnetic phenomena. The limit Absorption Method (LAM) which forms the basis of our study is presented. Theoretical results have been proved in the linear finite dimensional case. This method is applied to scattering problems and transport of charged particles. (authors)
2010-04-01
... 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 Director... is in compliance with the TERA; (b) The Director may extend the time for determining a...
Spectral self-imaging of time-periodic coherent frequency combs by parabolic cross-phase modulation.
Maram, Reza; Azaña, José
2013-11-18
Integer and fractional spectral self-imaging effects are induced on infinite-duration periodic frequency combs (probe signal) using cross-phase modulation (XPM) with a parabolic pulse train as pump signal. Free-spectral-range tuning (fractional effects) or wavelength-shifting (integer effects) of the frequency comb can be achieved by changing the parabolic pulse peak power or/and repetition rate without affecting the spectral envelope shape and bandwidth of the original comb. For design purposes, we derive the complete family of different pump signals that allow implementing a desired spectral self-imaging process. Numerical simulation results validate our theoretical analysis. We also investigate the detrimental influence of group-delay walk-off and deviations in the nominal temporal shape or power of the pump pulses on the generated output frequency combs.
Directory of Open Access Journals (Sweden)
Rehab F. Khalaf
2011-01-01
Full Text Available We study a queuing system which is equipped with a stand-by server in addition to the main server. The stand-by server provides service to customers only during the period of absence of the main server when either the main server is on a vacation or it is in the state of repairs due to a sudden failure from time to time. The service times, vacation times, and repair times are assumed to follow general arbitrary distributions while the stand-by service times follow exponential distribution. Supplementary variables technique has been used to obtain steady state results in explicit and closed form in terms of the probability generating functions for the number of customers in the queue, the average number of customers, and the average waiting time in the queue while the MathCad software has been used to illustrate the numerical results in this work.
Neff, H.; Laborde, H. M.; Lima, A. M. N.
2016-11-01
An oscillatory molecular adsorption pattern of the protein neutravidin from aqueous solution onto gold, in presence of a pre-deposited self assembled mono-molecular biotin film, is reported. Real time surface Plasmon resonance sensing was utilized for evaluation of the adsorption kinetics. Two different fractions were identified: in the initial phase, protein molecules attach irreversibly onto the Biotin ligands beneath towards the jamming limit, forming a neutravidin-biotin fraction. Afterwards, the growth rate exhibits distinct, albeit damped adsorption-desorption oscillations over an extended time span, assigned to a quasi reversibly bound fraction. These findings agree with, and firstly confirm a previously published model, proposing macro-molecular adsorption with time delay. The non-linear dynamic model is applicable to and also resembles non-damped oscillatory binding features of the hetero-catalytic oxidation of carbon monoxide molecules on platinum in the gas phase. An associated surface residence time can be linked to the dynamics and time scale required for self-organization.
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.
Directory of Open Access Journals (Sweden)
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.
High-frequency limit of non-autonomous gradient flows of functionals with time-periodic forcing
Plazotta, Simon; Zinsl, Jonathan
2016-12-01
We study the high-frequency limit of non-autonomous gradient flows in metric spaces of energy functionals comprising an explicitly time-dependent perturbation term which might oscillate in a rapid way. On grounds of the existence results by Ferreira and Guevara (2015) on non-autonomous gradient flows (which we also extend to a broader range of energy functionals), we prove that the associated solution curves converge to a solution of the time-averaged evolution equation in the limit of infinite frequency. Under additional assumptions on the energy, we obtain an explicit rate of convergence. Furthermore, we specifically investigate nonlinear drift-diffusion equations with time-dependent drift which formally are gradient flows with respect to the L2-Wasserstein distance. We prove that a family of weak solutions obtained as a limit of the Minimizing Movements scheme exhibits the above-mentioned behavior in the high-frequency limit.
Talei, Daryush; Valdiani, Alireza; Maziah, Mahmood; Mohsenkhah, Mohammad
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 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 GP(a3) ranged from 93% to 98%, they failed to reduce the MGT(a3). 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.
Directory of Open Access Journals (Sweden)
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.
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.…
Energy Technology Data Exchange (ETDEWEB)
Garcia Velarde, M.
1977-07-01
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.
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.
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...
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
In this paper,a class of discrete time non-autonomous competing system with feedback controls is considered. With the help of differential equations with piecewise constant arguments,we first propose a discrete model of a continuous non-autonomous competing system with feedback controls. Then,using the coincidence degree and the related continuation theorem as well as some priori estimations,a suficient condition for the existence of positive solutions to difference equations is obtained.
Institute of Scientific and Technical Information of China (English)
CHAN Kung-Sik; TONG Howell; STENSETH Nils Chr
2009-01-01
The study of the rodent fluctuations of the North was initiated in its modern form with Elton's pioneering work. Many scientific studies have been designed to collect yearly rodent abundance data, but the resulting time series are generally subject to at least two "problems": being short and non-linear. We explore the use of the continuous threshold autoregressive (TAR) models for analyzing such data. In the simplest case, the continuous TAR models are additive autoregressive models, being piecewise linear in one lag, and linear in all other lags. The location of the slope change is called the threshold parameter. The continuous TAR models for rodent abundance data can be derived from a general prey-predator model under some simplifying assumptions. The lag in which the threshold is located sheds important insights on the structure of the prey-predator system. We propose to assess the uncertainty on the location of the threshold via a new bootstrap called the nearest block bootstrap (NBB) which combines the methods of moving block bootstrap and the nearest neighbor bootstrap.The NBB assumes an underlying finite-order time-homogeneous Markov process. Essentially, the NBB bootstraps blocks of random block sizes, with each block being drawn from a non-parametric estimate of the future distribution given the realized past bootstrap series. We illustrate the methods by simulations and on a particular rodent abundance time series from Kilpisjarvi, Northern Finland.
Quasi-Periodicity, Chaos and Coexistence in the Time Delay Controlled Two-Cell DC-DC Buck Converter
Koubaâ, Karama; Feki, Moez
In addition to border collision bifurcation, the time delay controlled two-cell DC/DC buck converter is shown to exhibit a chaotic behavior as well. The time delay controller adds new design parameters to the system and therefore the variation of a parameter may lead to different types of bifurcation. In this work, we present a thorough analysis of different scenarios leading to bifurcation and chaos. We show that the time delay controlled two-cell DC/DC buck converter may also exhibit a Neimark-Sacker bifurcation which for some parameter set may lead to a 2D torus that may then break yielding a chaotic behavior. Besides, the saturation of the controller can also lead to the coexistence of a stable focus and a chaotic attractor. The results are presented using numerical simulation of a discrete map of the two-cell DC/DC buck converter obtained by expressing successive crossings of Poincaré section in terms of each other.
Lazar, Alpar S; Santhi, Nayantara; Hasan, Sibah; Lo, June C-Y; Johnston, Jonathan D; Von Schantz, Malcolm; Archer, Simon N; Dijk, Derk-Jan
2013-04-01
Sleep complaints and irregular sleep patterns, such as curtailed sleep during workdays and longer and later sleep during weekends, are common. It is often implied that differences in circadian period and in entrained phase contribute to these patterns, but few data are available. We assessed parameters of the circadian rhythm of melatonin at baseline and in a forced desynchrony protocol in 35 participants (18 women) with no sleep disorders. Circadian period varied between 23 h 50 min and 24 h 31 min, and correlated positively (n = 31, rs = 0.43, P = 0.017) with the timing of the melatonin rhythm relative to habitual bedtime. The phase of the melatonin rhythm correlated with the Insomnia Severity Index (n = 35, rs = 0.47, P = 0.004). Self-reported time in bed during free days also correlated with the timing of the melatonin rhythm (n = 35, rs = 0.43, P = 0.01) as well as with the circadian period (n = 31, rs = 0.47, P = 0.007), such that individuals with a more delayed melatonin rhythm or a longer circadian period reported longer sleep during the weekend. The increase in time in bed during the free days correlated positively with circadian period (n = 31, rs = 0.54, P = 0.002). Polysomnographically assessed latency to persistent sleep (n = 34, rs = 0.48, P = 0.004) correlated with the timing of the melatonin rhythm when participants were sleeping at their habitual bedtimes in the laboratory. This correlation was significantly stronger in women than in men (Z = 2.38, P = 0.017). The findings show that individual differences in circadian period and phase of the melatonin rhythm associate with differences in sleep, and suggest that individuals with a long circadian period may be at risk of developing sleep problems.
Institute of Scientific and Technical Information of China (English)
CHAN; Kung-Sik; TONG; Howell; STENSETH; Nils; Chr
2009-01-01
The study of the rodent fluctuations of the North was initiated in its modern form with Elton’s pioneering work.Many scientific studies have been designed to collect yearly rodent abundance data,but the resulting time series are generally subject to at least two "problems":being short and non-linear.We explore the use of the continuous threshold autoregressive(TAR) models for analyzing such data.In the simplest case,the continuous TAR models are additive autoregressive models,being piecewise linear in one lag,and linear in all other lags.The location of the slope change is called the threshold parameter.The continuous TAR models for rodent abundance data can be derived from a general prey-predator model under some simplifying assumptions.The lag in which the threshold is located sheds important insights on the structure of the prey-predator system.We propose to assess the uncertainty on the location of the threshold via a new bootstrap called the nearest block bootstrap(NBB) which combines the methods of moving block bootstrap and the nearest neighbor bootstrap.The NBB assumes an underlying finite-order time-homogeneous Markov process.Essentially,the NBB bootstraps blocks of random block sizes,with each block being drawn from a non-parametric estimate of the future distribution given the realized past bootstrap series.We illustrate the methods by simulations and on a particular rodent abundance time series from Kilpisjrvi,Northern Finland.
Institute of Scientific and Technical Information of China (English)
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...
Rostworowski, Andrzej
Motivated by the problem of stability of Anti-de Sitter (AdS) spacetime, we discuss nonlinear gravitational perturbations of maximally symmetric solutions of vacuum Einstein equations in general and the case of AdS in particular. We present the evidence that, similarly to the self-gravitating scalar field at spherical symmetry, the negative cosmological constant allows for the existence of globally regular, asymptotically AdS, time-periodic solutions of vacuum Einstein equations whose frequencies bifurcate from linear eigenfrequencies of AdS. Interestingly, our preliminary results indicate that the number of one parameter families of time-periodic solutions bifurcating from a given eigenfrequency equals the multiplicity of this eigenfrequency.
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Vasile Dragan
2015-07-01
Full Text Available We consider a discrete-time periodic generalized Riccati equation. We investigate a few iterative methods for computing the stabilizing solution. The first method is the Kleinman algorithm which is a special case of the classical Newton-Kantorovich procedure, the second one is a method of consistent iterations and two new Stein iterations. The proposed methods are tested and illustrated via some numerical examples.
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Pengfei Lin
Full Text Available The study of uterine gene expression patterns is valuable for understanding the biological and molecular mechanisms that occur during embryo implantation. Real-time quantitative RT-PCR (qRT-PCR is an extremely sensitive technique that allows for the precise quantification of mRNA abundance; however, selecting stable reference genes suitable for the normalization of qRT-PCR data is required to avoid the misinterpretation of experimental results and erroneous analyses. This study employs several mouse models, including an early pregnancy, a pseudopregnancy, a delayed implantation and activation, an artificial decidualization and a hormonal treatment model; ten candidate reference genes (PPIA, RPLP0, HPRT1, GAPDH, ACTB, TBP, B2M, 18S, UBC and TUBA that are found in uterine tissues were assessed for their suitability as internal controls for relative qRT-PCR quantification. GeNorm(PLUS, NormFinder, and BestKeeper were used to evaluate these candidate reference genes, and all of these methods identified RPLP0 and GAPDH as the most stable candidates and B2M and 18S as the least stable candidates. However, when the different models were analyzed separately, the reference genes exhibited some variation in their expression levels.
Maciejewski, G; Seeliger, M; Raetz, St; Bukowiecki, L; Kitze, M; Errmann, R; Nowak, G; Niedzielski, A; Popov, V; Marka, C; Gozdziewski, K; Neuhaeuser, R; Ohlert, J; Hinse, T C; Lee, J W; Lee, C -U; Yoon, J -N; Berndt, A; Gilbert, H; Ginski, Ch; Hohle, M M; Mugrauer, M; Roell, T; Schmidt, T O B; Tetzlaff, N; Mancini, L; Southworth, J; Dall'Ora, M; Ciceri, S; Zambelli, R; Corfini, G; Takahashi, H; Tachihara, K; Benko, J M; Sarneczky, K; Szabo, Gy M; Varga, T N; Vanko, M; Joshi, Y C; Chen, W P
2013-01-01
The transiting planet WASP-12 b was identified as a potential target for transit timing studies because a departure from a linear ephemeris was reported in the literature. Such deviations could be caused by an additional planet in the system. We attempt to confirm the existence of claimed variations in transit timing and interpret its origin. We organised a multi-site campaign to observe transits by WASP-12 b in three observing seasons, using 0.5-2.6-metre telescopes. We obtained 61 transit light curves, many of them with sub-millimagnitude precision. The simultaneous analysis of the best-quality datasets allowed us to obtain refined system parameters, which agree with values reported in previous studies. The residuals versus a linear ephemeris reveal a possible periodic signal that may be approximated by a sinusoid with an amplitude of 0.00068+/-0.00013 d and period of 500+/-20 orbital periods of WASP-12 b. The joint analysis of timing data and published radial velocity measurements results in a two-planet m...
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...
The time narrating of prose in the Seventeen-Year Period%论十七年时期散文的时间叙事
Institute of Scientific and Technical Information of China (English)
颜水生
2014-01-01
十七年时期散文在时间叙事方面具有鲜明特征，主要表现为时间的意识形态化、历史决定论和历史化方法三个方面。在十七年散文中，时间具有强烈的现实指向性，负载了丰富的意识形态内涵，成为社会意识形态的符码；强调过去—现在—未来的紧密关系，遵行过去—现在—未来的线性发展规律，强调社会历史发展的必然性和规律性，忽略了社会历史发展的偶然性和曲折性；把时间放置在历史进程中进行理解和认识，或者把时间与特定历史阶段进行对比，体现出一种历史主义态度。%The Seventeen-Year Period is a brand-new historical period, which reflected a sharp time sense and history ideas. The time narrating of prose in the Seventeen-Year Period has distinctive characteristics, mainly for the time of ideology, historical determinism and historicized, etc. In the prose of the seventeen years, the time has strong practical orientation, loading rich ideological connotation, and thus becoming the social ideological codes. The works emphasize the close relationship between the past, the present and the future, walk along the past-present-future linear developmen law and emphasize the inevitability and regularity of the social historical development, while ignoring the Contingency and twists of the social and historical development. They place the time in the historical process for understanding and awareness, or compare the time with the specific historical stage so as to understand and process time with historical strategy. Marx’s time theory has important guiding significance on the prose research.
Yang, Jun; Laycock, Silas; Christodoulou, Dimitris; Drake, Jeremy J.; Hong, Jaesub; Antoniou, Vallia; Zezas, Andreas; Coe, Malcolm; Ho, Wynn
2017-01-01
We have collected and analyzed 116 {\\itshape XMM-Newton\\/}, 151 {\\itshape Chandra\\/}, and 952 {\\itshape RXTE\\/} observations of the Small Magellanic Cloud (SMC), spanning 1997-2014. The resulting observational library provides a comprehensive view of the physical, temporal and statistical properties of the SMC pulsar population across the luminosity range of $L_X= 10^{31.5}-10^{38}$~erg~s$^{-1}$. We report $\\sim$1600 individual pulsar detections, yielding $\\sim$1300 pulse period measurements. Our pipeline generates a suite of products for each pulsar detection: period, flux, event list, high time-resolution light-curve, pulse-profile, periodogram and X-ray spectrum. Upper-limits are estimated for all non-detections bringing the combined database to $\\sim$37,000 observations of 67 pulsars. Combining all three satellites, we generated complete histories of the spin periods, pulse amplitudes, pulse fractions and X-ray luminosities. Many of the pulsars show variations in pulse period due to the combination of orbital motion and accretion torques. Long-term spin-up/down trends are seen in 27/25 pulsars respectively, pointing to sustained transfer of mass and angular momentum to the neutron star on decadal timescales. The distributions of pulse-detection and flux as functions of spin-period provide interesting findings: mapping boundaries of accretion-driven X-ray luminosity, and showing that fast pulsars ($Prarely detected, yet are more prone to giant outburst. Accompanying this paper is an initial public release of the library so that it can be used by other researchers. We intend the database and pulse profile library to be useful in driving improved models of neutron star magnetospheres and accretion physics.
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.
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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.
de Avellar, Marcio G B; Altamirano, Diego; Sanna, Andrea; Zhang, Guobao
2015-01-01
We present an analysis of the energy and frequency dependence of the Fourier time lags of the hectoHertz quasi-periodic oscillations (QPOs) and of the QPOs at the frequency at which the power density spectrum shows a break in the neutron-star low-mass X-ray binary 4U 1636-53, using a large data set obtained with the Rossi X-ray Timing Explorer. We found that: (i) For the break frequency QPO: for low frequencies, in general the time lag is positive, but it is decreasing with increasing frequency, reaching zero lag at 20 Hz. Between 20 and 35 Hz there is a small fluctuation around zero, from where the time lags become positive again and increase slightly above zero up to 65 Hz. (ii) For the hHz QPO: we see that when the frequency is 100 Hz the time lag is negative, but it increases to zero already at 110 Hz, being consistent with this value up to 130 Hz from where it increases to 0.5 msec at around 140 Hz. From 140 Hz the time lag decreases sharply, being strongly negative for hHz greater than 220 Hz. We compar...
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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
Ganesh, Sri; Brar, Sheetal
2016-01-01
Purpose 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). PMID:26869754
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).
Pangle, L. A.; Cardoso, C.; Kim, M.; Lora, M.; Wang, Y.; Troch, P. A. A.; Harman, C. J.
2014-12-01
Water molecules traverse myriad flow paths and spend different lengths of time on or within the landscape before they are discharged into a stream channel. The transit-time distribution (TTD) is a probability distribution that represents the range and likelihood of transit times for water and conservative solutes within soils and catchments, and is useful for comparative analysis and prediction of solute transport into streams. The TTD has customarily been assumed to be time-invariant in practical applications, but is understood to vary due to unsteady flow rates, changes in water-balance partitioning, and shifting flow pathways. Recent theoretical advances have clarified how the distribution of transit times experienced by water and solutes within a stream channel at any moment in time is conditional on the specific series of precipitation events preceding that time. Observations resolving how TTDs vary during a specific sequence of precipitation events could be obtained by introducing unique and conservative tracers during each event and quantifying their distinct breakthrough curves in the stream. At present, the number of distinct and conservative tracers available for this purpose is insufficient. Harman and Kim [Harman, C.J. and Kim, M., 2014, Geophysical Research Letters, 41, 1567-1575] proposed a new experimental method—based on the establishment of periodic steady-state conditions—that allows multiple overlapping breakthrough curves of non-unique tracers to be decomposed, thus enabling analysis of the distinct TTDs associated with their specific times of introduction through precipitation. We present results from one of the first physical experiments to test this methodology. Our experiment involves a sloping lysimeter (10° slope) that contains one cubic meter of crushed basalt rock (loamy sand texture), an irrigation system adaptable to controlled tracer introductions, and instruments that enable total water balance monitoring. We imposed a repeated
La Parola, V; Cusumano, G; Segreto, A; Masetti, N; Melandri, A
2013-01-01
IGR J11305-6256 is one of the numerous sources discovered through the INTEGRAL scan of the Galactic Plane. Thanks to the Swift-BAT survey, that allows the frequent sampling of any sky region, we have discovered in the hard X-ray emission of this source a modulation with a period of ~120.83 d. The significance of this periodic modulation is ~4 standard deviations in Gaussian statistics. We interpret it as the orbital period of the binary system. We derive an orbital separation between IGR J11305-6256 and its companion star of ~286 R$_{\\odot}$ corresponding to ~19 times the radius of the companion star. The broadband XRT-BAT (0.3-150 keV) spectrum is described either by the sum of a black-body and a cut-off power-law or by a partially absorbed cut-off power-law. The temporal and spectral characteristics of the source indicate its possible association with the class of persistent, but faint, Be X-ray binary systems.
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.
Provost, Christine; Garcia, Omar; GarçOn, VéRonique
1992-11-01
We study the dominant periodic variations of sea surface temperature (SST) in the Brazil-Malvinas Confluence region from a satellite-derived data set compiled by Olson et al. (1988). This data set is composed of 202 sea surface temperature images with a 4 × 4 km resolution and extends over 3 years (from July 1984 to July 1987). Each image is a 5-day composite. The dominant signal, as already observed by Podesta et al. (1991), has a 1-year period. We first fit a single-frequency sinusoidal model of the annual cycle in order to estimate mean temperature, amplitude, and phase at 159 points uniformly distributed over the region. The residuals are generally small (less than 2°C). The largest departures from this cycle are located either in the Brazil-Malvinas frontal region or in the southeastern part of the region. Other periods in SST variations are identified by means of periodograms of the 159 residual time series in which the annual cycle has been substracted. The periodograms show that a semiannual frequency signal is present at almost every location. The ratio of the semiannual amplitude to the annual amplitude increases southward from 0% at 30°S to reach up to 45% at 50°S. In the south the semiannual signal creates an asymmetry, and the resulting (total) annual cycle has a cold period (winter) longer than the warm one (summer). In the frontal region the annual and semiannual signals have an important interannual variation. This semiannual frequency is associated with the semiannual wave present in the atmospheric forcing of the southern hemisphere. Differential heating over the mid-latitude oceans and the high-latitude ice-covered Antarctic Continent has been suggested as the cause of this semiannual wave (Van Loon, 1967).
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.
Nerlich, A G; Rohrbach, H; Zink, A
2002-09-01
The scientific investigation of mummies and skeletons provides considerable data for the reconstruction of the living conditions and diseases of past populations. We describe the data on four completely analyzed tomb complexes from the huge necropolis of Thebes-West in Upper Egypt dating to different time periods. A total of 211 individuals from the so-called "Middle Kingdom" (MK, c. 2050-1750 BC) were compared to 273 individuals from the "New Kingdom" (NK) to "Late Period" (LP, in total 1550-500 BC). The age at death and the sex ratio were comparable between both groups. There was a high rate of early death with a maximum between the 2nd and 3rd decade of life but infant/adolescent burials were comparably rare. This early death is assumed to be due to an elevated prevalence of various infectious diseases. Likewise, a high rate of tuberculosis infections was seen in those individuals regardless of which time period they came from. Metabolic disorders with osseous manifestations, such as scurvy, osteomalacia and chronic anemia (cribra orbitalia, porotic hyperostosis) were found with a high frequency in the MK populations but significantly less in the NK-LP populations. On the other hand signs of trauma were comparably high, and lesions due to degenerative joint and vertebral diseases were significantly higher in LP than in MK or NK individuals suggesting a higher mechanical load in the later populations. Cases of malignant (secondary) bone tumors and various soft tissue/organ diseases indicate that "civilization" disorders were present when the living conditions assured survival into advanced age. In summary, we provide circumstantial evidence that the systematic and concise analysis of mummy and skeletal remains can allow a reconstruction of major aspects of life and disease in historic populations, although a complete reconstruction is not possible.
Mayur, Manik; Amiroudine, Sakir; Lasseux, Didier; Chakraborty, Suman
2014-03-01
Electro-osmotic flows (EOF) have seen remarkable applications in lab-on-a-chip based microdevices owing to their lack of moving components, durability, and nondispersive nature of the flow profiles under specifically designed conditions. However, such flows may typically suffer from classical Faradaic artifacts like electrolysis of the solvent, which affects the flow rate control. Such a problem has been seen to be overcome by employing time periodic EOFs. Electric field induced transport of a conductive liquid is another nontrivial problem that requires careful study of interfacial dynamics in response to such an oscillatory flow actuation. The present study highlights the role of electric field generated Maxwell stress and free surface potential along with the electric double layer thickness and forcing frequency, toward influencing the interfacial transport and fluid flow in free-surface electro-osmosis under a periodically varying external electric field, in a semi-analytical formalism. Our results reveal interesting regimes over which the pertinent interfacial phenomena as well as bulk transport characteristics may be favorably tuned by employing time varying electrical fields.
Durmaz, Gül; Us, Tercan; Aydinli, Aydin; Kiremitci, Abdurrahman; Kiraz, Nuri; Akgün, Yurdanur
2003-01-01
We tracked and documented the time of positivity of blood cultures by using the BACTEC 9120 (Becton Dickinson Diagnostic Instrument Systems) blood culture system over a 5-year study period. A 7-day protocol of the incubation period was selected, and a total of 11,156 blood cultures were evaluated. The clinically significant microorganisms (32.95%) were isolated in 3,676 specimens. Gram-positive and -negative bacterial isolation rates were found to be 41.07 and 44.88%, respectively. Yeasts were found in 14.03% of all pathogens. Both the false-positivity and -negativity rates were very low (0.1 and 0.3%, respectively). The mean detection times for all of the pathogens were determined to be 19.45 h. Yeasts, nonfermentative gram-negative bacteria, and Brucella melitensis strains were isolated within 5 days. By taking these data into account, we decided to establish a 5-day-incubation protocol in our laboratory instead of the 7 days that are commonly used. PMID:12574291
Durmaz, Gül; Us, Tercan; Aydinli, Aydin; Kiremitci, Abdurrahman; Kiraz, Nuri; Akgün, Yurdanur
2003-02-01
We tracked and documented the time of positivity of blood cultures by using the BACTEC 9120 (Becton Dickinson Diagnostic Instrument Systems) blood culture system over a 5-year study period. A 7-day protocol of the incubation period was selected, and a total of 11156 blood cultures were evaluated. The clinically significant microorganisms (32.95%) were isolated in 3676 specimens. Gram-positive and -negative bacterial isolation rates were found to be 41.07 and 44.88%, respectively. Yeasts were found in 14.03% of all pathogens. Both the false-positivity and -negativity rates were very low (0.1 and 0.3%, respectively). The mean detection times for all of the pathogens were determined to be 19.45 h. Yeasts, nonfermentative gram-negative bacteria, and Brucella melitensis strains were isolated within 5 days. By taking these data into account, we decided to establish a 5-day-incubation protocol in our laboratory instead of the 7 days that are commonly used.
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
Hwang, Eui-Ryong; Kim, Tae-Young
2013-12-01
This research mainly dealt with sanitation and hygiene related editorials quoted from educational magazines published in Chosun until the Manchurian Incident during the Japanese colonial period. The study revealed that modern Japan became aware of the importance of public sanitation from the late nineteenth century and established modern programs so that schools can comprehensively teach students about sanitation and hygiene so as to enter modern imperial society. Japan particularly introduced and carried out modern physical(gymnastics) education as a means of "complete sanitation and hygiene" to improve students' health. As a result of having two times of war, the Japanese Empire reaffirmed the significance of modern sanitation and hygiene. After colonization of Chosun, Japan organized official educational groups and enlightened the public about sanitation and hygiene through editorials on the educational magazines which the groups had published. In order for schools to promote complete sanitation and hygiene based on modern medicine, Japan actively engaged in suggesting the necessity of physical(gymnastics) education which was critical to human's growth and development. After Japanese Government-General of Korea legislated on school hygiene in 1913, Japanese governments school started hiring school doctors and nurses. They stressed the need of providing sanitation and hygiene education in school to prepare for war in 1910's in advance; highlighted that physical (gymnastics) education should be enforced to help students grow and improve their physical strength from a modern medical point of view. In April, 1919, the Japanese Empire implemented the same instruction to the schools where Chosun people attended. But it was found that the law was not applied well to those schools in effect. The Japanese Empire was seen to proclaim the second educational decree in 1922; proposed international hygienic achievement of the time and comments; enlightened the public by
Aliani, Stefano; Meloni, Roberto; Dando, Paul R.
2004-05-01
Time-series data sets of total bottom pressure (tidal plus atmospheric), seawater temperature and sediment temperature from a marine shallow hydrothermal vent (Milos, Hellenic Volcanic Arc, Aegean Sea) were studied to determine factors influencing periodicity at the vents. Bottom pressure and vent temperature were mainly opposite in phase, with the main fluctuations of vent temperature occurring at tidal frequencies. Although the fluctuations in atmospheric pressure were of the same order as those due to tidal pressure, the contribution of atmospheric pressure was considerably weaker at diurnal frequencies. Some sudden discontinuities in sediment temperature were recorded, at least one of these may have been caused by seismic events. Seawater temperature changes were not reflected in the sediment temperature record. Transient loadings, such as tidal loadings, barometric pressure and earth tides, may affect the pore pressure in sediments, influencing fluid expulsion and sediment temperature as a consequence. Most of the contribution to the fluctuations in sediment temperature depends on tidal loadings. Gravitational forces, in the form of earth tides, can also be involved and barometric pressure is probably responsible for long period temperature oscillations.
Littlefield, Colin; Cain, Ryan; Mumme, Raymond; Magno, Katrina C; Corpuz, Taylor; Sandefur, Davis; Boyd, David; Cook, Michael; Ulowetz, Joseph
2014-01-01
We report the results of a twenty-five-month photometric campaign studying V1432 Aql, the only known eclipsing, asynchronous polar. Our data show that both the residual eclipse flux and eclipse O-C timings vary strongly as a function of the spin-orbit beat period. Relying upon a new model of the system, we show that cyclical changes in the location of the threading region along the ballistic trajectory of the accretion stream could produce both effects. This model predicts that the threading radius is variable, in contrast to previous studies which have assumed a constant threading radius. Additionally, we identify a very strong photometric maximum which is only visible for half of the beat cycle. The exact cause of this maximum is unclear, but we consider the possibility that it is the optical counterpart of the third accreting polecap proposed by Rana et al. (2005). Finally, the rate of change of the white dwarf's spin period is consistent with it being proportional to the difference between the spin and or...
Miyazaki, Yosuke; Watari, Yasuhiko; Tanaka, Kazuhiro; Goto, Shin G
2016-03-01
Soil temperature cycles are considered to play an important role in the entrainment of circadian clocks of underground insects. However, because of the low conductivity of soil, temperature cycles are gradually dampened and the phase of the temperature cycle is delayed with increasing soil depth. The onion fly, Delia antiqua, pupates at various soil depths, and its eclosion is timed by a circadian clock. This fly is able to compensate for the depth-dependent phase delay of temperature change by advancing the eclosion time with decreasing amplitude of the temperature cycle. Therefore, pupae can eclose at the appropriate time irrespective of their location at any depth. However, the mechanism that regulates eclosion time in response to temperature amplitude is still unknown. To understand whether this mechanism involves the circadian clock or further downstream physiological processes, we examined the expression patterns of period (per), a circadian clock gene, of D. antiqua under temperature cycles that were square wave cycles of 12-h warm phase (W) and 12-h cool phase (C) with the temperature difference of 8 °C (WC 29:21 °C) and 1 °C (WC 25.5:24.5 °C). The phase of oscillation in per expression was found to commence 3.5h earlier under WC 25.5:24.5 °C as compared to WC 29:21 °C. This difference was in close agreement with the eclosion time difference between the two temperature cycles, suggesting that the mechanism that responds to the temperature amplitude involves the circadian clock.
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.
网络化控制系统采样周期的实时优化%Real-time Optimization of Sampling Period for Networked Control Systems
Institute of Scientific and Technical Information of China (English)
车高峰; 郭海智
2012-01-01
With the development of computer science and technology, control theory and communication technology, networked control systems have got more and more attention. Because of limited resources, there exist network-induced delays inevitably in the networked control systems, which can degrade the systems performance at a certain extent. The problem of optimal assignment of sampling period is studied in order to optimize the performance of networked control systems. The cost function of subsystems is elected according to sampling period, network-induced delay and character- istic of noise. Based on these, a real-time feedback scheduler is developed to periodically assign new sampling period based on current plant states of subsystem and noise intensities. At last, the experiment is presented.%随着计算机科学技术、控制理论和网络通信技术的发展，网络化控制系统受到越来越多的关注．由于网络化控制系统的网络带宽的限制使得网络化控制系统不可避免地存在网络诱导时延，网络诱导时延在一定程度上会降低网络化控制系统的性能．为了优化整个控制系统的性能，文章研究了系统采样周期的优化问题，提出了实时反馈调度器．为此，系统目标函数的选取根据采样周期、网络诱导时延以及作用在系统上的噪声，具体做法根据当前各个子系统中被控对象的状态和噪声特性，周期地分配新的采样周期给各个子系统，最后给出实验结果．
Trabelsi, Awatef; Jaworski, Andrzej; Kamler, Ewa; Gardeur, Jean-Noël; Teletchea, Fabrice; Ayadi, Habib; Fontaine, Pascal
2016-04-01
Size, caloric value and chemical composition were measured separately in the progeny of two northern pike (Esox lucius) females at 3-day intervals during the endogenous feeding period from hatching to final yolk resorption. Tissue, yolk and entire larvae were analysed separately in three groups of larvae that hatched at different times (between 88 and 106 degree-days post-fertilization). An integrated approach with the Gompertz model was used to compute the yolk conversion efficiency and time to maximum tissue size in early, mid and late hatched larvae. At hatching, unresorbed yolk of early hatched larvae contained more energy (39.20 J) and more protein (0.99 mg) compared to the yolk of larvae that hatched later (38.13 J and 0.92 mg protein for late hatched larvae, p < 0.05). In contrast, a significant reduction in tissue weight (-0.7 mg DW) and protein content (-0.5 mg) was found in early hatched larvae compared to those which hatched later (p < 0.05). Between days 9 and 12 post-hatching (108 and 144 degree-days post-hatching), close to the final yolk resorption, late hatched larvae stopped growing and their tissue began to be resorbed. This tissue resorption time was delayed in early hatched larvae which presented at the end of the experiment a greater tissue weight than late hatched ones. Yolk conversion efficiency in term of energy from hatching to complete yolk resorption stage was significantly higher for early and mid hatched larvae (51%) compared to late hatched ones (44%) (p = 0.004). Furthermore, the time to maximum tissue size was found to be negatively related to hatching time which implies that early hatched larvae take longer time to switch from one developmental stage to the next. The maximum tissue dry weight and energy content were found to be reached at approximately the same age post-fertilization for both early hatched and late hatched larvae, suggesting that the principal steps in a fish's lifespan are better correlated with time of
Zhu, W
2001-09-01
A new guided wave transducer model, time-delay periodic ring arrays (TDPRAs), is proposed and investigated in this paper for guided cylindrical wave generation and reception in hollow cylinders with application interests focusing on non-destructive testing (NDT) of piping/tubing. A finite element simulation has been performed for axisymmetric guided-mode excitation and reception with TDPRAs. By arranging a proper configuration of the time-delay profile and the electric-connection pattern of a ring array, unidirectional excitation and reception of guided waves can be achieved. The numerical results are obtained for the first three axisymmetrical modes and are compared with respect to generation efficiency and mode selectivity. Parametric influences on the performance of TDPRAs are discussed, combining a 2-D phase velocity-frequency spectrum approach with the mode dispersion and displacement structure analyses. The identification of converted modes in guided cylindrical wave reflections with a flexible TDPRA receiver has also been studied through sample notch reflection.
O'Donoghue, James; Melin, Henrik; Stallard, Tom S.; Provan, G.; Moore, Luke; Badman, Sarah V.; Cowley, Stan W. H.; Baines, Kevin H.; Miller, Steve; Blake, James S. D.
2016-01-01
On 19-21 April 2013, the ground-based 10-m W.M. Keck II telescope was used to simultaneously measure H3+ emissions from four regions of Saturn's auroral ionosphere: (1) the northern noon region of the main auroral oval; (2) the northern midnight main oval; (3) the northern polar cap and (4) the southern noon main oval. The H3+ emission from these regions was captured in the form of high resolution spectral images as the planet rotated. The results herein contain twenty-three H3+ temperatures, column densities and total emissions located in the aforementioned regions - ninety-two data points in total, spread over timescales of both hours and days. Thermospheric temperatures in the spring-time northern main oval are found to be cooler than their autumn-time southern counterparts by tens of K, consistent with the hypothesis that the total thermospheric heating rate is inversely proportional to magnetic field strength. The main oval H3+ density and emission is lower at northern midnight than it is at noon, in agreement with a nearby peak in the electron influx in the post-dawn sector and a minimum flux at midnight. Finally, when arranging the northern main oval H3+ parameters as a function of the oscillation period seen in Saturn's magnetic field - the planetary period oscillation (PPO) phase - we see a large peak in H3+ density and emission at ∼115° northern phase, with a full-width at half-maximum (FWHM) of ∼44°. This seems to indicate that the influx of electrons associated with the PPO phase at 90° is responsible at least in part for the behavior of all H3+ parameters. A combination of the H3+ production and loss timescales and the ±10° uncertainty in the location of a given PPO phase are likely, at least in part, to be responsible for the observed peaks in H3+ density and emission occurring at a later time than the peak precipitation expected at 90° PPO phase.
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.
Directory of Open Access Journals (Sweden)
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.
Directory of Open Access Journals (Sweden)
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
Directory of Open Access Journals (Sweden)
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.
Kaliszan, Michał
2013-09-01
This paper presents a verification of the thermodynamic model allowing an estimation of the time of death (TOD) by calculating the post mortem interval (PMI) based on a single eyeball temperature measurement at the death scene. The study was performed on 30 cases with known PMI, ranging from 1h 35min to 5h 15min, using pin probes connected to a high precision electronic thermometer (Dostmann-electronic). The measured eye temperatures ranged from 20.2 to 33.1°C. Rectal temperature was measured at the same time and ranged from 32.8 to 37.4°C. Ambient temperatures which ranged from -1 to 24°C, environmental conditions (still air to light wind) and the amount of hair on the head were also recorded every time. PMI was calculated using a formula based on Newton's law of cooling, previously derived and successfully tested in comprehensive studies on pigs and a few human cases. Thanks to both the significantly faster post mortem decrease of eye temperature and a residual or nonexistent plateau effect in the eye, as well as practically no influence of body mass, TOD in the human death cases could be estimated with good accuracy. The highest TOD estimation error during the post mortem intervals up to around 5h was 1h 16min, 1h 14min and 1h 03min, respectively in three cases among 30, while for the remaining 27 cases it was not more than 47min. The mean error for all 30 cases was ±31min. All that indicates that the proposed method is of quite good precision in the early post mortem period, with an accuracy of ±1h for a 95% confidence interval. On the basis of the presented method, TOD can be also calculated at the death scene with the use of a proposed portable electronic device (TOD-meter).
Edelman, Theresa L. B.; McCulloch, Katherine A.; Barr, Angela; Frøkjær-Jensen, Christian; Jorgensen, Erik M.; Rougvie, Ann E.
2016-01-01
The Caenorhabditis elegans heterochronic gene pathway regulates the relative timing of events during postembryonic development. lin-42, the worm homolog of the circadian clock gene, period, is a critical element of this pathway. lin-42 function has been defined by a set of hypomorphic alleles that cause precocious phenotypes, in which later developmental events, such as the terminal differentiation of hypodermal cells, occur too early. A subset of alleles also reveals a significant role for lin-42 in molting; larval stages are lengthened and ecdysis often fails in these mutant animals. lin-42 is a complex locus, encoding overlapping and nonoverlapping isoforms. Although existing alleles that affect subsets of isoforms have illuminated important and distinct roles for this gene in developmental timing, molting, and the decision to enter the alternative dauer state, it is essential to have a null allele to understand all of the roles of lin-42 and its individual isoforms. To remedy this problem and discover the null phenotype, we engineered an allele that deletes the entire lin-42 protein-coding region. lin-42 null mutants are homozygously viable, but have more severe phenotypes than observed in previously characterized hypomorphic alleles. We also provide additional evidence for this conclusion by using the null allele as a base for reintroducing different isoforms, showing that each isoform can provide heterochronic and molting pathway activities. Transcript levels of the nonoverlapping isoforms appear to be under coordinate temporal regulation, despite being driven by independent promoters. The lin-42 null allele will continue to be an important tool for dissecting the functions of lin-42 in molting and developmental timing. PMID:27729432
Edelman, Theresa L B; McCulloch, Katherine A; Barr, Angela; Frøkjær-Jensen, Christian; Jorgensen, Erik M; Rougvie, Ann E
2016-12-07
The Caenorhabditis elegans heterochronic gene pathway regulates the relative timing of events during postembryonic development. lin-42, the worm homolog of the circadian clock gene, period, is a critical element of this pathway. lin-42 function has been defined by a set of hypomorphic alleles that cause precocious phenotypes, in which later developmental events, such as the terminal differentiation of hypodermal cells, occur too early. A subset of alleles also reveals a significant role for lin-42 in molting; larval stages are lengthened and ecdysis often fails in these mutant animals. lin-42 is a complex locus, encoding overlapping and nonoverlapping isoforms. Although existing alleles that affect subsets of isoforms have illuminated important and distinct roles for this gene in developmental timing, molting, and the decision to enter the alternative dauer state, it is essential to have a null allele to understand all of the roles of lin-42 and its individual isoforms. To remedy this problem and discover the null phenotype, we engineered an allele that deletes the entire lin-42 protein-coding region. lin-42 null mutants are homozygously viable, but have more severe phenotypes than observed in previously characterized hypomorphic alleles. We also provide additional evidence for this conclusion by using the null allele as a base for reintroducing different isoforms, showing that each isoform can provide heterochronic and molting pathway activities. Transcript levels of the nonoverlapping isoforms appear to be under coordinate temporal regulation, despite being driven by independent promoters. The lin-42 null allele will continue to be an important tool for dissecting the functions of lin-42 in molting and developmental timing.
Institute of Scientific and Technical Information of China (English)
王斌
2011-01-01
Based on the theory of the time scales and topological degree theory, by using continuation theorem of coincidence degree theory and some skills of integral inequalities on time scales, the sufficient condition of the existence of periodic solutions for a non-autonomous predator-prey system with time delays on time scales is obtained. The obtained result has practical significance and application value in ecological management.%在时标理论和拓扑度理论基础之上，通过应用重合度理论的连续定理和一些时标上积分不等式技巧，给出了时标上一类具有可变时滞的非自治捕食者一食饵系统周期解存在性的充分条件。取得的结果在生态管理中具有现实意义和应用价值。
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
A large earthquake (MW=7.6) occurred in Jiji (Chi-Chi), Taiwan, China on September 20, 1999, and was followed by many moderate-size shocks in the following days. Two of the largest aftershocks with the magnitudes of MW=6.1 and MW=6.2, respectively, were used as empirical Green(s functions (EGFs) to obtain the source time functions (STFs) of the main shock from long-period waveform data of the Global Digital Seismograph Network (GDSN) including IRIS, GEOSCOPE and CDSN. For the MW=6.1 aftershock of September 22, there were 97 pairs of phases clear enough from 78 recordings of 26 stations; for the MW=6.2 aftershock of September 25, there were 81 pairs of phases clear enough from 72 recordings of 24 stations. For each station, 2 types of STFs were retrieved, which are called P-STF and S-STF due to being from P and S phases, respectively. Totally, 178 STF individuals were obtained for source-process analysis of the main shock. It was noticed that, in general, STFs from most of the stations had similarities except that those in special azimuths looked different or odd due to the mechanism difference between the main shock and the aftershocks; and in detail, the shapes of the STFs varied with azimuth. Both of them reflected the stability and reliability of the retrieved STFs. The comprehensive analysis of those STFs suggested that this event consisted of two sub-events, the total duration time was about 26 s, and on the average, the second event was about 7 s later than the first one, and the moment-rate amplitude of the first event was about 15% larger than that of the second one.
Energy Technology Data Exchange (ETDEWEB)
Baghban Khojasteh, Nasrin, E-mail: khojasteh.nasrin@gmail.com [Nuclear Engineering Department, Science and Research Branch, Islamic Azad University, Poonak Sq. PO Box 14515-775, Tehran (Iran, Islamic Republic of); Pazirandeh, Ali [Nuclear Engineering Department, Science and Research Branch, Islamic Azad University, Poonak Sq. PO Box 14515-775, Tehran (Iran, Islamic Republic of); Jameie, Behnam [Nuclear Engineering Department, Science and Research Branch, Islamic Azad University, Poonak Sq. PO Box 14515-775, Tehran (Iran, Islamic Republic of); Laboratory of Basic Science and Neuroscience, Basic Science Dept, Faculty of Allied Medicine, Cellular and Molecular Research Center, Tehran University of Medical Science, Pardis-e-Hemmat,Tehran (Iran, Islamic Republic of); Goodarzi, Samereh [Nuclear Engineering Department, Science and Research Branch, Islamic Azad University, Poonak Sq. PO Box 14515-775, Tehran (Iran, Islamic Republic of)
2012-06-15
Distribution of {sup 10}B in different regions of rat normal brain was studied. Two groups were chosen as control and trial. Trial group received 2 ml of neutral boron compound. 2, 4 and 6 h after the injection brain removed, coronal sections of forebrain, midbrain and hindbrain were sandwiched between two pieces of polycarbonate. Autoradiography plots of {sup 10}B distribution showed significant differences in three regions with the highest {sup 10}B concentration in the forebrain during 4 h after injection. - Highlights: Black-Right-Pointing-Pointer Normal tissue tolerance is very important in BNCT. Black-Right-Pointing-Pointer This study has been done to determine {sup 10}B distribution in three anatomical regions of rat normal brain. Black-Right-Pointing-Pointer These specific regions of brain have not been studied in previous BNCT projects. Black-Right-Pointing-Pointer We found significant differences in {sup 10}B distribution between these three regions. Black-Right-Pointing-Pointer In different time periods after neutral boron compound injection, there has been a significant difference in boron absorption.
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...
... You may also have other symptoms, such as lower back pain, nausea, diarrhea, and headaches. Period pain is not ... Taking a hot bath Doing relaxation techniques, including yoga and meditation You might also try taking over- ...
... blood become too low or too high. Some women have irregular periods because their bodies produce too much androgen, which is a hormone that causes increased muscle mass, facial hair, and deepening of the voice in males and ...
Jolivet, Romain; Lasserre, Cecile; Doin, Marie-Pierre; Guillaso, Stéphane; Cavalié, Olivier; Peltzer, Gilles; Sun, Jianbao; Rong, Dailu; Shen, Zheng-Kang; Xu, Xiwei
2010-05-01
We use SAR interferometry to measure the strain accumulation along the left-lateral Haiyuan fault system (HFS), that marks the north-eastern boundary of the tibetan plateau. The last major earthquakes that occured along the HFS are the M~8 1920 Haiyuan earthquake (strike-slip mechanism) and the Ml=8-8.3 1927 Gulang earthquake that ruptured a thrust fault system. No large earthquake is reported on the central section of the HFS, the "Tianzhu seismic gap", since ~1000 years. We first analyze the complete ENVISAT SAR data archive along 4 descending and 2 ascending tracks for the 2003-2009 period and construct an InSAR-based mean Line-Of-Sight (LOS) velocity map around the HFS from the eastern end of the Qilian shan (102° E), to the west, to the Liupan shan (106° E), to the east. Data are processed using a small baseline chain type. For each track, all radar images are coregistrated to a single master and interferograms are produced using a local adaptative range filtering. Residual orbital and atmospheric delays are jointly inverted and corrected for each unwrapped interferogram. Atmospheric corrections are validated using the ERA40 global atmospheric model (ECMWF). The interferograms series on each track are then inverted to obtain the increments of LOS radar delays between acquisition dates, adapting the Lopez-Quiroz et al. 2009 time series analysis. The obtained LOS mean velocity maps show a dominant left-lateral motion across the fault with along-strike variations: some fault sections are locked at shallow depth while others are creeping and local vertical movements are observed (subsidence in the "Jingtai" pull-apart basin). For various fault slip rates imposed below 20 km (4-10 mm/yr), we model the shallow velocity by inverting the mean LOS velocity maps for both strike-slip and dip-slip motion on vertical, 5km x 2.5km discretized patches, using a least-square method with an appropriate degree of smoothing. The fault geometry follows the surface trace of the
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...
Dufour, Elise; Goepfert, Nicolas; Gutiérrez Léon, Belkys; Chauchat, Claude; Jordán, Régulo Franco; Vásquez Sánchez, Segundo
2014-01-01
Llama (Lama glama) and alpaca (Vicugna pacos) are the only large domesticated animals indigenous to the Americas. Pastoralism occupies a fundamental economic, social and religious role in Andean life. Today, camelid livestock are confined to the ecozone of the puna (above 3,500 masl), while their presence on the Pacific coast during pre-Hispanic times is attested by archaeological skeletal remains. This study aims to document herding practices on the northern Peruvian coast during the Early Intermediate Period (200 BC-600 AD) by gaining insights into diet, location of breeding and mobility of archaeological camelids from the funerary and ritual contexts of two Mochica sites, Uhle Platform in Huacas de Moche and El Brujo. The three first early years and the long-term life histories of the animals were documented by the combined bulk analysis of bone collagen (δ(13)C col and δ(15)N col) and bone structural carbonate (δ(13)C bone and δ(18)O bone) and the serial analysis of structural carbonate of molar tooth enamel (δ(13)C enamel and δ(18)O enamel). Mochica camelids were bred in the low and/or middle valleys, unlike their modern counterparts, who are restricted to highland puna C3 pastures. Archaeological camelids had diverse and complex life histories, usually with substantial maize foddering. An ontogenetic switch in diet and possible residential mobility during the course of life were identified for some specimens. Although the inference of geographic origin from δ(18)O bone and δ(18)O enamel values was limited because of the lack of understanding of the influence of environmental and biological factors, tooth enamel analysis has great potential for exploring camelid herding practices and Andean pastoralism. Our study suggested that Mochica herders adapted their practices to the difficult lowland environment and that herding practices were varied and not restricted to breeding at higher altitudes. The role of maize in different aspects of the economic life
Zorn, Telma M T; Soto-Suazo, Mauricio; Pellegrini, Cleusa R; Oliveira, José G; Stumpf, Walter E
2003-07-01
The presence and changes of estradiol nuclear binding and related functions in uterine luminal and glandular epithelium were studied before and after blastocyst implantation using receptor autoradiography with (3)H-estradiol-17beta in association with (3)H-thymidine incorporation and immunocytochemical binding of antibody to estrogen receptor ER-alpha. (3)H-estradiol nuclear binding is present but variable during days 1.5-7.5 of pregnancy. Sites of strong nuclear binding of (3)H-estradiol exhibit strong immunocytochemical staining with ER-alpha antibody. Qualitative and quantitative evaluation of autoradiograms reveal that there is a general increase of nuclear (3)H-estradiol binding during the first 3 days after fertilization in both luminal and glandular epithelium. The binding of estradiol is stronger in glandular epithelium from day 2.5 to day 7.5, paralleled by a rise in (3)H-thymidine incorporation on day 2.5. By comparison, in the epithelium of the uterine lumen (3)H-estradiol nuclear binding is low, but relatively high in epithelial cells at lateral branching of the lumen where the increase in (3)H-estradiol binding corresponds to an increased labeling index with (3)H-thymidine. A highly differentiated binding of (3)H-estradiol to luminal and glandular epithelium was demonstrated with region- and time-specific changes of related effects on cell proliferation, differentiation, and secretion, probably involving involution and remodeling. The strong (3)H-estradiol binding to glandular epithelium suggests that estradiol exerts pronounced effects on glandular activities in the periimplantation period.
Jolivet, R.; Lasserre, C.; Doin, M.; Guillaso, S.; Cavalie, O.; Peltzer, G.; Sun, J.; Shen, Z.
2009-12-01
We use sar interferometry to characterize the present-day behaviour of the left-lateral Haiyuan fault system (HFS), one of the main geological structure at the north-eastern boundary of the tibetan plateau that accomodates the eastward movement of Tibet relative to the Gobi-Ala Shan platform. The last major earthquakes that occured along the HFS are the M~8 1920 Haiyuan earthquake (strike-slip mechanism) and the Ml=8-8.3 1927 Gulang earthquake that ruptured a nearby thrust fault system. A ~260 km-long seismic gap has been identified on the central part of the HFS, along which creep may occur. We propose to further investigate the relationships between the present day deformation processes observed along the HFS and its seismic history and segmentation. We construct an extended InSAR-based map of the deformation around the Haiyuan fault from the eastern end of the Qilian Shan (102° E), to the west, to the junction with the Liupan Shan (106° E), to the east. We use monthly ENVISAT acquisitions along 4 descending and 2 ascending tracks, spanning the 2003-2009 time period. Data are processed using a small baseline chain type. For each track, all radar images are coregistrated to a single master and interferograms are produced using a local adaptative range filtering. Residual orbital and atmospheric effects are jointly inverted and corrected for each unwrapped interferogram. Atmospheric corrections are validated “a posteriori” , using the most recent global atmospheric model. We also investigate the potential improvements of these models for “a priori” atmospheric corrections. The interferograms series on each track are then inverted to obtain the increments of Line Of Sight (LOS) radar delays between acquisition dates, adapting the Lopez-Quiroz et al. 2009 time series analysis. We derive LOS mean velocity maps, that show along-strike variations including local shallow creep and vertical movements (subsidence in the Jingtai pull-apart basin). These features
Teymuri, Ghulam Heidar; Sadeghian, Marzieh; Kangavari, Mehdi; Asghari, Mehdi; Madrese, Elham; Abbasinia, Marzieh; Ahmadnezhad, Iman; Gholizadeh, Yavar
2013-01-01
Background: One of the significant dangers that threaten people’s lives is the increased risk of accidents. Annually, more than 1.3 million people die around the world as a result of accidents, and it has been estimated that approximately 300 deaths occur daily due to traffic accidents in the world with more than 50% of that number being people who were not even passengers in the cars. The aim of this study was to examine traffic accidents in Tehran and forecast the number of future accidents using a time-series model. Methods: The study was a cross-sectional study that was conducted in 2011. The sample population was all traffic accidents that caused death and physical injuries in Tehran in 2010 and 2011, as registered in the Tehran Emergency ward. The present study used Minitab 15 software to provide a description of accidents in Tehran for the specified time period as well as those that occurred during April 2012. Results: The results indicated that the average number of daily traffic accidents in Tehran in 2010 was 187 with a standard deviation of 83.6. In 2011, there was an average of 180 daily traffic accidents with a standard deviation of 39.5. One-way analysis of variance indicated that the average number of accidents in the city was different for different months of the year (P < 0.05). Most of the accidents occurred in March, July, August, and September. Thus, more accidents occurred in the summer than in the other seasons. The number of accidents was predicted based on an auto-regressive, moving average (ARMA) for April 2012. The number of accidents displayed a seasonal trend. The prediction of the number of accidents in the city during April of 2012 indicated that a total of 4,459 accidents would occur with mean of 149 accidents per day during these three months. Conclusion: The number of accidents in Tehran displayed a seasonal trend, and the number of accidents was different for different seasons of the year. PMID:26120405
Napp, Diego; Shankar, Shiva
2010-01-01
This paper studies behaviors that are defined on a torus, or equivalently, behaviors defined in spaces of periodic functions, and establishes their basic properties analogous to classical results of Malgrange, Palamodov, Oberst et al. for behaviors on R^n. These properties - in particular the Nullstellensatz describing the Willems closure - are closely related to integral and rational points on affine algebraic varieties.
Napp, Diego; Put, Marius van der; Shankar, Shiva
2010-01-01
This paper studies behaviors that are defined on a torus, or equivalently, behaviors defined in spaces of periodic functions, and establishes their basic properties analogous to classical results of Malgrange, Palamodov, Oberst et al. for behaviors on R(n). These properties-in particular the Nullste
Energy Technology Data Exchange (ETDEWEB)
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.
Energy Technology Data Exchange (ETDEWEB)
Henderson, Calen B. [Department of Astronomy, Ohio State University, 140 W. 18th Ave., Columbus, OH 43210 (United States); Stassun, Keivan G., E-mail: henderson@astronomy.ohio-state.edu [Department of Physics and Astronomy, Vanderbilt University, VU Station B 1807, Nashville, TN 37235 (United States)
2012-03-01
We have conducted a long-term, wide-field, high-cadence photometric monitoring survey of {approx}50,000 stars in the Lagoon Nebula H II 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 days < P < 10 days; 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{sub X} /L{sub bol} Almost-Equal-To -3.3). However, we find a significant positive correlation between L{sub X} /L{sub bol} and corotation radius, suggesting that the observed X-ray luminosities are regulated by centrifugal stripping of the stellar coronae. The period-mass relationship in NGC 6530 is broadly similar to that of the Orion Nebula Cluster (ONC), but the slope of the relationship among the slowest rotators differs from that in the ONC and other young clusters. We show that the slope of the period-mass relationship for the slowest rotators can be used as a proxy for the age of a young cluster, and we argue that NGC 6530 may be slightly younger than the ONC, making it a particularly important touchstone for models of angular momentum evolution in young, low-mass stars.
Directory of Open Access Journals (Sweden)
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.
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...
Liu, Shu-Zheng; Zhang, Fang; Quan, Pei-Liang; Lu, Jian-Bang; Liu, Zhi-Cai; Sun, Xi-Bin
2012-01-01
In recent decades, decreasing trends in esophageal cancer mortality have been observed across China. We here describe esophageal cancer mortality trends in Linzhou city, a high-incidence region of esophageal cancer in China, during 1988-2010 and make a esophageal cancer mortality projection in the period 2011-2020 using a Bayesian approach. Age standardized mortality rates were estimated by direct standardization to the World population structure in 1985. A Bayesian age-period-cohort (BAPC) analysis was carried out in order to investigate the effect of the age, period and birth cohort on esophageal cancer mortality in Linzhou during 1988-2010 and to estimate future trends for the period 2011-2020. Age-adjusted rates for men and women decreased from 1988 to 2005 and changed little thereafter. Risk increased from 30 years of age until the very elderly. Period effects showed little variation in risk throughout 1988-2010. In contrast, a cohort effect showed risk decreased greatly in later cohorts. Forecasting, based on BAPC modeling, resulted in a increasing burden of mortality and a decreasing age standardized mortality rate of esophageal cancer in Linzhou city. The decrease of esophageal cancer mortality risk since the 1930 cohort could be attributable to the improvements of social- economic environment and lifestyle. The standardized mortality rates of esophageal cancer should decrease continually. The effect of aging on the population could explain the increase in esophageal mortality projected for 2020.
Institute of Scientific and Technical Information of China (English)
殷勤
2014-01-01
电力营销稽查是电力营销环节内控约束机制的主要组成部分，是电力营销风险管理的重要内容和有效途径。介绍在“三集五大”建设背景下，结合江苏苏州地域特色和苏州供电公司工作实际，从现实需求和管理创新角度对营销稽查工作办法进行探索，提出“时序等级排列、时点定置监控、时段动态控制”的措施，切实推动营销稽查精益化管理水平再度提升。%Electric power marketing inspection is the main part of the internal restraint mechanism of electric power market-ing link, is an important content and effective way of electric power marketing risk management. Under the background of"three inte-grations and five large constructions“and combined with regional characteristics of Suzhou and the actual work of Suzhou power sup-ply company, the article explores the marketing inspection work method from the realistic demand and the management innovation, puts forward measuresof”sequential rank order, time point set monitoring, time periods dynamic control", in order to promote mar-keting inspection lean management to further higher level.
Ammar, Boudour; Chérif, Farouk; Alimi, Adel M
2012-01-01
This paper is concerned with the existence and uniqueness of pseudo almost-periodic solutions to recurrent delayed neural networks. Several conditions guaranteeing the existence and uniqueness of such solutions are obtained in a suitable convex domain. Furthermore, several methods are applied to establish sufficient criteria for the globally exponential stability of this system. The approaches are based on constructing suitable Lyapunov functionals and the well-known Banach contraction mapping principle. Moreover, the attractivity and exponential stability of the pseudo almost-periodic solution are also considered for the system. A numerical example is given to illustrate the effectiveness of our results.
Potgieter, M. S.; Le Roux, J. A.
1992-01-01
A time-dependent drift model is used to simulate the heliospheric modulation of galactic cosmic rays, with emphasis on the effects of the wavy heliospheric neutral sheet (HNS) as a function of time during the period 1985-1990. The model predicted a clearly defined time difference between the time when minimum modulation occurred at earth and at radial distances farther away from the sun, indicating that the HNS plays an important part in establishing this observed time delay. The movements of the Voyager 1 and 2 and Pioneer 10 spacecraft were simulated in order to calculate instantaneous radial and latitudinal gradients. The time dependencies of these gradients were found to follow the observations well. The model study indicates that the HNS cannot be ignored, especially during periods of low to moderate solar activity, when the modulation of cosmic rays is described.
Institute of Scientific and Technical Information of China (English)
胡猛; 王健
2013-01-01
A class of Gilpin-Ayalasystem with time delays was studied. By using the properties of almost periodic system and Lyapunov-Razumikhin technique, the sufficient conditions were obtained for the existence of its strictly positive almost periodic solution.%研究一类具有时滞的Gilpin-Ayala系统,运用概周期系统的性质与Lyapunov-Razuminkhin技巧,给出其存在严格正概周期解的充分条件.
Directory of Open Access Journals (Sweden)
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.
Institute of Scientific and Technical Information of China (English)
嵇小辅; 杨泽斌; 孙玉坤; 苏宏业
2008-01-01
The problem of roust stabilization for linear time-varying uncertain periodic descriptor systems is revisited. Based on the concept of robust stability for linear time-varying uncer-tain periodic descriptor systems, a necessary and sufficient con-dition for robust stability is put forward. The robust stabiliza-tion problem is also studied and the corresponding necessary and sufficient condition is given using the notation of dual system.The obtained matrix inequality conditions can be transformed to linear matrix inequality ones with the introduction of some free matrices, which makes the analysis and design procedure simple and reliable.
Jansen, N.W.D.; Roosendaal, G.; Bijlsma, J.W.J.; Groot, J. de; Lafeber, F.P.J.G.
2007-01-01
Objective. Joint bleeding, or hemarthrosis, leads in time to severe joint damage. This study was carried out to test the in vitro thresholds of exposure time and concentration that lead to irreversible joint damage, to add to the discussion on the usefulness of aspiration of the joint after a hemorr
Historically defined autobiographical periods
DEFF Research Database (Denmark)
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...... over time and theoretical implications are discussed, notably by introducing a new approach to autobiographical memory, Transition Theory, which assumes that autobiographical memory is organized by transitional events that can be selfinitiated or externally imposed - historically defined...
Institute of Scientific and Technical Information of China (English)
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.
DEFF Research Database (Denmark)
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...... sensitivity by 13 dB compared to a nonflat-top pulse is reported.......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...
Mann, Andrew W.; Newton, Elisabeth R.; Rizzuto, Aaron C.; Irwin, Jonathan; Feiden, Gregory A.; Gaidos, Eric; Mace, Gregory N.; Kraus, Adam L.; James, David J.; Ansdell, Megan; Charbonneau, David; Covey, Kevin R.; Ireland, Michael J.; Jaffe, Daniel T.; Johnson, Marshall C.; Kidder, Benjamin; Vanderburg, Andrew
2016-09-01
We confirm and characterize a close-in ({P}{{orb}} = 5.425 days), super-Neptune sized ({5.04}-0.37+0.34 {R}\\oplus ) planet transiting K2-33 (2MASS J16101473-1919095), a late-type (M3) pre-main-sequence (11 Myr old) star in the Upper Scorpius subgroup of the Scorpius-Centaurus OB association. The host star has the kinematics of a member of the Upper Scorpius OB association, and its spectrum contains lithium absorption, an unambiguous sign of youth (\\lt 20 Myr) in late-type dwarfs. We combine photometry from K2 and the ground-based MEarth project to refine the planet’s properties and constrain the host star’s density. We determine K2-33’s bolometric flux and effective temperature from moderate-resolution spectra. By utilizing isochrones that include the effects of magnetic fields, we derive a precise radius (6%-7%) and mass (16%) for the host star, and a stellar age consistent with the established value for Upper Scorpius. Follow-up high-resolution imaging and Doppler spectroscopy confirm that the transiting object is not a stellar companion or a background eclipsing binary blended with the target. The shape of the transit, the constancy of the transit depth and periodicity over 1.5 yr, and the independence with wavelength rule out stellar variability or a dust cloud or debris disk partially occulting the star as the source of the signal; we conclude that it must instead be planetary in origin. The existence of K2-33b suggests that close-in planets can form in situ or migrate within ˜10 Myr, e.g., via interactions with a disk, and that long-timescale dynamical migration such as by Lidov-Kozai or planet-planet scattering is not responsible for all short-period planets.
Directory of Open Access Journals (Sweden)
Yunxiang Zhu
Full Text Available Airway mucin secretion studies have focused on goblet cell responses to exogenous agonists almost to the exclusion of baseline mucin secretion (BLMS. In human bronchial epithelial cell cultures (HBECCs, maximal agonist-stimulated secretion exceeds baseline by ~3-fold as measured over hour-long periods, but mucin stores are discharged completely and require 24 h for full restoration. Hence, over 24 h, total baseline exceeds agonist-induced secretion by several-fold. Studies with HBECCs and mouse tracheas showed that BLMS is highly sensitive to mechanical stresses. Harvesting three consecutive 1 h baseline luminal incubations with HBECCs yielded equal rates of BLMS; however, lengthening the middle period to 72 h decreased the respective rate significantly, suggesting a stimulation of BLMS by the gentle washes of HBECC luminal surfaces. BLMS declined exponentially after washing HBECCs (t1/2 = 2.75 h, to rates approaching zero. HBECCs exposed to low perfusion rates exhibited spike-like increases in BLMS when flow was jumped 5-fold: BLMS increased >4 fold, then decreased within 5 min to a stable plateau at 1.5-2-fold over control. Higher flow jumps induced proportionally higher BLMS increases. Inducing mucous hyperplasia in HBECCs increased mucin production, BLMS and agonist-induced secretion. Mouse tracheal BLMS was ~6-fold higher during perfusion, than when flow was stopped. Munc13-2 null mouse tracheas, with their defect of accumulated cellular mucins, exhibited similar BLMS as WT, contrary to predictions of lower values. Graded mucous metaplasia induced in WT and Munc13-2 null tracheas with IL-13, caused proportional increases in BLMS, suggesting that naïve Munc13-2 mouse BLMS is elevated by increased mucin stores. We conclude that BLMS is, [i] a major component of mucin secretion in the lung, [ii] sustained by the mechanical activity of a dynamic lung, [iii] proportional to levels of mucin stores, and [iv] regulated differentially from agonist
Directory of Open Access Journals (Sweden)
Marietta Rottenkolber
Full Text Available Inhaled, long-acting beta-2-adrenoceptor agonists (LABA have well-established roles in asthma and/or COPD treatment. Drug utilisation patterns for LABA have been described, but few studies have directly compared LABA use in different countries. We aimed to compare the prevalence of LABA-containing prescriptions in five European countries using a standardised methodology.A common study protocol was applied to seven European healthcare record databases (Denmark, Germany, Spain, the Netherlands (2, and the UK (2 to calculate crude and age- and sex-standardised annual period prevalence rates (PPRs of LABA-containing prescriptions from 2002-2009. Annual PPRs were stratified by sex, age, and indication (asthma, COPD, asthma and COPD.From 2002-2009, age- and sex-standardised PPRs of patients with LABA-containing medications increased in all databases (58.2%-185.1%. Highest PPRs were found in men ≥ 80 years old and women 70-79 years old. Regarding the three indications, the highest age- and sex-standardised PPRs in all databases were found in patients with "asthma and COPD" but with large inter-country variation. In those with asthma or COPD, lower PPRs and smaller inter-country variations were found. For all three indications, PPRs for LABA-containing prescriptions increased with age.Using a standardised protocol that allowed direct inter-country comparisons, we found highest rates of LABA-containing prescriptions in elderly patients and distinct differences in the increased utilisation of LABA-containing prescriptions within the study period throughout the five European countries.
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
Institute of Scientific and Technical Information of China (English)
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.
Time Narrative and Cultural Symptom of the “Period Series”%“年代剧”中的时间叙事与文化症候∗
Institute of Scientific and Technical Information of China (English)
申朝晖
2014-01-01
Time narrative is a typical feature of “period series”,in which story time shows its duel na-ture,fictional time corresponding to the true historical time.But most of the“period series”show pref-erence to the historical time,especially to evoke patriotism,or direct at no specific historical time.In addition,they also incline to express the continuality of time that internalized in some characters through bleak reminiscence.%年代剧中的时间叙事极富特色，其故事时间具有双重性，虚构的故事时间与真实的历史时间之间形成互文照应关系，而且年代剧大多偏爱以民族主义精神强调或省略特定的历史时刻。另外，通过苍凉的想像式怀旧感伤，年代剧还表现个体生命内在时间的绵延特质。
THE WAVELET TRANSFORM OF PERIODIC FUNCTION AND NONSTATIONARY PERIODIC FUNCTION
Institute of Scientific and Technical Information of China (English)
刘海峰; 周炜星; 王辅臣; 龚欣; 于遵宏
2002-01-01
Some properties of the wavelet transform of trigonometric function, periodic function and nonstationary periodic function have been investigated. The results show that the peak height and width in wavelet energy spectrum of a periodic function are in proportion to its period. At the same time, a new equation, which can truly reconstruct a trigonometric function with only one scale wavelet coefficient, is presented. The reconstructed wave shape of a periodic function with the equation is better than any term of its Fourier series. And the reconstructed wave shape of a class of nonstationary periodic function with this equation agrees well with the function.
Hamdan, Mohamed A.; Brook, George A.
2015-12-01
There is very little dated evidence on wet periods in the Eastern Desert and Sinai Peninsula of Egypt during the Late Pleistocene and Holocene. To obtain such information, we have studied the petrography, isotope geochemistry and AMS radiocarbon ages of mostly relict tufas deposited by springs draining perched ground water bodies in metamorphic and volcanic rocks. The tufas unconformably overly Precambrian basic igneous rocks (basalt, diabase and gabbro). As the ages of tufa carbonate are frequently older than the true ages of the deposits because of the incorporation of old, 14C-dead carbon, we have dated both the carbonate matrix and insoluble organic material of the tufas. These ages show that the tufas were largely formed during two broad time periods, the most recent from 12,058 to 6678 cal yr BP (African Humid Period), and the other from ˜31,200-22,500 cal yr BP, with preferential growth during the coldest times of this period namely during Heinrich Events 2 and 3 (H2 and H3) and the Last Glacial Maximum (LGM). The time span between 19,000-9000 cal yr BP, including the YD and H1, appears to have been relatively more arid than the earlier LGM or H2 periods or the later Holocene. The Late Pleistocene tufas are depleted in 18O relative to the Holocene tufas and were deposited at a lower temperature (˜14.0°-20.8 °C vs. 18.4°-23.4 °C). We believe that the Holocene tufas in the Sinai were formed by rainfall from the Mediterranean and those in the southern part of the Eastern Desert by African monsoon rainfall derived from the Red Sea-Gulf of Aden and Indian Ocean. In contrast, the moisture that fed the Late Pleistocene tufas, which are depleted in 18O relative to Holocene deposits, and progressively depleted from north to south, was probably brought by the Westerlies from the Atlantic-Mediterranean Sea when the Westerly circulation was pushed southwards during the coldest periods of the Late Pleistocene. Periods of tufa deposition correlate with major
Periodic feedback stabilization for linear periodic evolution equations
Wang, Gengsheng
2016-01-01
This book introduces a number of recent advances regarding periodic feedback stabilization for linear and time periodic evolution equations. First, it presents selected connections between linear quadratic optimal control theory and feedback stabilization theory for linear periodic evolution equations. Secondly, it identifies several criteria for the periodic feedback stabilization from the perspective of geometry, algebra and analyses respectively. Next, it describes several ways to design periodic feedback laws. Lastly, the book introduces readers to key methods for designing the control machines. Given its coverage and scope, it offers a helpful guide for graduate students and researchers in the areas of control theory and applied mathematics.
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.
Oscillations following periodic reinforcement.
Monteiro, Tiago; Machado, Armando
2009-06-01
Three experiments examined behavior in extinction following periodic reinforcement. During the first phase of Experiment 1, four groups of pigeons were exposed to fixed interval (FI 16s or FI 48s) or variable interval (VI 16s or VI 48s) reinforcement schedules. Next, during the second phase, each session started with reinforcement trials and ended with an extinction segment. Experiment 2 was similar except that the extinction segment was considerably longer. Experiment 3 replaced the FI schedules with a peak procedure, with FI trials interspersed with non-food peak interval (PI) trials that were four times longer. One group of pigeons was exposed to FI 20s PI 80s trials, and another to FI 40s PI 160s trials. Results showed that, during the extinction segment, most pigeons trained with FI schedules, but not with VI schedules, displayed pause-peck oscillations with a period close to, but slightly greater than the FI parameter. These oscillations did not start immediately after the onset of extinction. Comparing the oscillations from Experiments 1 and 2 suggested that the alternation of reconditioning and re-extinction increases the reliability and earlier onset of the oscillations. In Experiment 3 the pigeons exhibited well-defined pause-peck cycles since the onset of extinction. These cycles had periods close to twice the value of the FI and lasted for long intervals of time. We discuss some hypotheses concerning the processes underlying behavioral oscillations following periodic reinforcement.
Institute of Scientific and Technical Information of China (English)
徐昌进; 廖茂新
2011-01-01
In this paper, we study the existence of positive periodic solutions of a mutual and impulsive system with periodic time delay and periodic coefficients by using the continuation theorem of coincidence degree theory.A verifiable sufficient condition for the existence of at least one positive periodic solution of the system is obtained.An illustrative example is given to demonstrate the feasibility and effectiveness of the obtained results.The results are significant and useful in both theoretical and practical importance in population dynamics, especially in mutual system fields.Our result is a good complement to the earlier study on mutual system with time delay.%运用重合度理论中的连续性定理研究了一类具有周期时滞和周期系数的脉冲互惠系统的正周期解的存在性,得到了该系统至少存在一个正周期解的一个易于检验的充分条件,给出了一个具体例子来说明所得结论的可行性和正确性.所得结果在种群动力学研究领域,特别是互惠系统研究领域中具有理论和现实的应用价值,该结果是对前人研究具有时滞的互惠系统的有益补充.
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朱景修; 熊超; 刘桂兰; 蒲红斌; 严移胜
2011-01-01
According to the homogenization temperature of the brine inclusions generated with hydrocarbon fluid enclosures and integrating with the buried and heat histories of the typical wells, the period & times and time of reservoir formation in Wangji-Xinzhuang region are determined: early petroleum reservoir mainly formed in the sedimentary periods from late period of He No. 1 Interval to Liaozhuang Formation; late one principally happened in the rising period of late period of Liaozhuang Formation-the key reservoir forming period of the current oilfield. The main migration period of the oil and gas should be earlier than the forming period of the key fractures in Wangji-' Xinzhuang region. The fracture generation results in the damage and redistribution of the primary oil reservoirs and furthermore provides the migration channels and enrichment space for the petroleum generated in He No. 3 Upper Interval. At the same time, shallow secondary oil reservoirs are generated in He No. 2 Interval. According to the petroleum trace of nitrogen-bearing compound and the background of regional geology, the migration path is from the mature source rock located in the southern deep sag to Wangji, faults (sandbodies) and Xinzhuang region, finally the petroleum reservoir formed whenever it encountered with the trap.%根据与烃类流体包裹体相伴生的盐水包裹体的均一化温度,结合典型井的埋藏史、热史确定了王集—新庄地区成藏期次和时间:早期油气成藏期主要发生在核一段末期—廖庄组沉积期；晚期油气成藏期主要发生在廖庄末抬升期,是形成现今油田的主要成藏期.油气主要运移期应早于王集—新庄地区主要断裂的形成期.断层的形成导致原生油藏的破坏和再分配,也为核三上段生成的油气提供了运移通道和聚集场所,在核二段形成浅层次生油藏.根据含氮化合物油气示踪及区域地质背景认为,油气运移路径为南侧深凹成熟烃源
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王智诚; 王双明
2013-01-01
利用动力系统方法及持久性理论研究了一类时间周期的时滞非局部反应扩散单种群增长模型，建立了解的全局存在性以及一致持久性。%The paper was concerned with a class of delayed nonlocal reaction-diffusion equation with a time period, which modelled the growth of a single species. By using the monotone dynamical system method and practice persistence theory, the global existence and uniform persistence of solutions were established.
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
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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.
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夏永梅; 叶红晖; 李向云; 厉郡华
2013-01-01
Objective To investigate the effects of time periods and astronomical tides on the onset of intracerebral hemorrhage in Rizhao region. Methods A total of 509 patients with intracerebral hemorrhage in Rizhao region were collected from January 1, 2006 to December 31, 2010. Using a circular distribution method, the concentration (r) of onset time of patients was calculated first, and then the mean ā an-gle and the dispersion angle (s) were calculated. The time and peak period of the onset of intracerebral hemorrhage were predicted at different time periods and different astronomical tidal periods ( new moon, full moon, first quarter, last quarter and other periods) . Rayleigh test was used for significant difference test. Results ①Among the 509 patients with intracerebral hemorrhage, 340 patients were occurred during the daytime (7:00 to 19 :00) and 169 patients during the night (19 :00 to 7:00) . The former was 2. 01 times than the later. The circular distribution analysis showed (-α) =205° ,Z = 32. 803 (P<0.001). When (-α) was at 11:00 to 13:00, it was the centralized time of the onset;s =94. 87°,(-α) ±s = 109.77° to 299.52°, the peak hours of onset were 5:00 to 19:00. ②117 patients had intracerebral hemorrhage during the new moon and full moon periods, 92 had intracerebral hemorrhage during the first quarter and last quarter periods, and 300 had intracerebral hemorrhage at the other times. The results of the circular distribution analysis showed (-α)= 53 ,27° ,Z =8. 0226 (P<0.001).(-α) in the new moon and full moon periods was the centralized time of the onset of intracerebral hemorrhage, s = 80. 16° ,(-α) ± s = -26. 89° to 133.43°, the peak hours were mainly the new moon, full moon, first quarter, and last quarter periods. Conclusion The distribution of intracerebral hemorrhage onset has circadian cycle rhythms. The onset during the daytime is higher than the night time,and associated with the changes of the astronomical tidal rhythms
Institute of Scientific and Technical Information of China (English)
陈伟
2012-01-01
In this article, Collected more than 400 cases of global earthquakes （Global earthquakes greater than 7.5 and China earthquake greater than 7.0） from the year 1201 so far, earthquake cases in the calculation of the time difference between any two data, we found two basic cycles 11 and 30,no matter what the time scale selected, such as year, month or day. This global seismic time distribution model is called ＂11 and 30 global earthquakes time periodic law＂. ARer outlining the content of this law, this article focus on revealing the hidden nature of the physical laws more ＂11/30 time two-dimensional coordinate system＂.%根据收集到的自公元1201年以来全球7．5级／中国7．O级以上强震共400余例，通过计算每个震例之间的年差、月差（如取近期发生的地震亦可计算其日差，结果完全类似），发现在不同时间尺度中均存在着两个基本周期数：11与30；根据这两个基本周期数表达出的地震时间分布规律称为“全球地震11／30周期分布律”；本文在概要介绍“11／30地震周期律”基础上，来重点揭示在这一周期律背后所隐藏的更为本质的物理规律：“11／30二维时间坐标系”。
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林芸; 陈亦旋; 刘运清; 刘才华
2009-01-01
OBJECTIVE To investigate the time to add weaning period diet to infants and young children whether had an effect on chiidren'cavitas otis motor function, pronunciation and dysarthria. METHODS Surveyed children' parents of experimental group (added weaning period diet earlily)and control group(addod weaning period diet as normal) by one to one questionnaire investigation, got the information of weaning period diet, evaluated the children cavitas otis motor function, pronunciation and misartieulation and analysed the dependability between the time and dysarthria. RESULTS There were significant difference between experimental and control group in dysarthria and motor functional disturbance(P<0.01 ). CONCLUSIONS Added weaning period diet eariily during 4 to 6 months old can promote cavitas otis motor function and diminish dysarthria opportunity.%目的 探讨婴幼儿时期添加断乳期饮食的时间对儿童口腔运动功能、儿童发音和构音障碍的影响.方法 通过对实验组及对照组儿童父母进行一对一问卷调查,了解其断乳期饮食添加情况,评价儿童的口腔运动功能、发音及构音情况,从而分析断乳期饮食添加时间与儿童构音障碍的相关性.结果 伴构音障碍的实验组儿童多伴有口腔运动的功能障碍,且未能及时添加断乳期饮食,与对照组比较,两者有显著性差异(P<0.01).结论 4～6月尽早添加断乳期饮食,能促进口腔运动功能,从而减少儿童构音异常的发生机会.
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王金平; 许建平; 徐杨军
2011-01-01
研究了恒定导通时间(constant on-time,COT)控制buck变换器的多开关周期振荡现象,揭示了buck变换器输出电容等效串联电阻(equivalent series resistance,ESR)对COT控制buck变换器控制性能的影响.研究结果表明,输出电容等效串联电阻是buck变换器发生多开关周期振荡现象的关键因素,并给出了COT控制buck变换器发生多开关周期振荡的临界ESR值.当输出电容ESR值小于临界值时,发生多开关周期振荡现象;而当ESR大于临界值时,多开关周期振荡现象消失.最后,仿真结果验证了理论分析的正确性.%In this paper, multi-switching period oscillation phenomenon in constant on-time (COT) controlled buck converter is studied, and the effect of output capacitor equivalent series resistance (ESR) on the control performance of COT controlled buck converter is revealed. The study results indicate that ESR is the critical factor causing multi-switching period oscillation phenomenon in the COT controlled buck converter, and critical value of ESR is obtained. When the value of ESR is less than the critical value, the multi-switching period oscillation phenomenon occurs, and it disappears when the value of ESR is higher than the critical value. Finally, the theoretical results are verified by simulation.
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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
时标上两种群竞争动力系统周期解的存在性%Periodic solutions for two-species competition dynamic system on time scales
Institute of Scientific and Technical Information of China (English)
王斌
2012-01-01
Based on the theory of the time scales and topological degree theory, by using continuation theorem of coincidence degree theory and some skills of integral inequalities on time scales, the sufficient condition of the existence of periodic solutions for a non-autonomous two-species Lotka-Voherra competition system on time scales is obtained. The obtained result has practical significance and application value in ecological management.%在时标理论和拓扑度理论基础之上，通过应用重合度理论的连续定理和一些时标上积分不等式技巧，给出了时标上一类非自治两种群Lotka—Volterra竞争系统正周期解存在性的充分条件．取得的结果在生态管理中具有现实意义和应用价值．
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张少林; 韦明俊
2006-01-01
研究了一类时滞Predator-Prey系统,其中Prey种群是具有两个生命阶段的种群,即幼年阶段和成年阶段.Predator种群只能捕食Prey幼年种群.通过应用Gaines和Mawhin重合度理论的连续函数定理,给出了系统正周期解存在的充分条件.%A Predator-Prey system with time delay is considered. There are, immature and mature, two stage for prey species in the system. By using the continuation theorem of Gaines and Mawhin's coincidence degree theory, a sufficient condition is derived for the existence periodic positive solution.
[Periodic breathing with periodic oxygen variation in infancy].
von Czettritz, G; Bax, R T; Eckardt, T; Springer, S; Emmrich, P
1996-01-01
Oxycardiorespirographies, recording arterial oxygen saturation (SaO2), breathing movements, heart rate and ECG with a mean recording time of 22.3 hours, were performed on 85 preterm (mean postconceptional age: 38 weeks) and 81 term infants (mean postconceptional age 42.4 weeks). 83% of the preterm infants showed periodic breathing (PB), in 97% of them this was accompanied by periodic variations of arterial oxygen saturation (PVO). Periodic breathing occurred in 61% of the term infants, 84% of them showed PVO during periodic breathing. The mean variation of oxygen saturation was between 92.8 and 96.8% (+/- 1.7) for preterm and between 92.9 and 96.0% (+/- 2.2) for term infants. In some infants the peak to peak amplitude of the SaO2 cycles was up to 22%, sometimes a further fall of SaO2 occurred. There was a strong correlation of the PVO both at the beginning and end of the episode as well as with the PB-cycle periodicity itself. The fall of the oxygen saturation occurred 3.1 to 7.8 s after the beginning of the first apnea of an episode of periodic breathing, the minimum SaO2 was reached approximately 4.2 to 8.6 s later. This periodic rapid fall of SaO2 from a high oxygenation level cannot be explained by the apneas of a rather short duration during periodic breathing. It is discussed that PVO during periodic breathing may be caused by an ideopathic right to left shunting across fetal circulation pathways which occurs intermittently and periodically. This mechanism could-via patterns of reaction exhibited during the fetal and neonatal time period-lead to acute hypoxemia, as found in apparently life threatening events (ALTE) and as postulated in sudden infant death (SID).
Directory of Open Access Journals (Sweden)
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
Institute of Scientific and Technical Information of China (English)
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
Hyperkalemic periodic paralysis
Periodic paralysis - hyperkalemic; Familial hyperkalemic periodic paralysis; HyperKPP; HyperPP; Gamstorp disease ... factors include having other family members with periodic paralysis. It affects men more often than women.
A highly specific test for periodicity
Energy Technology Data Exchange (ETDEWEB)
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.
Institute of Scientific and Technical Information of China (English)
张雁
2014-01-01
Objective To investigation and study the impact of standing time in pregnancy period for pregnancy complications. Methods To choose 460 cases of pregnant women who make card and had delivery from January 2010 to May 2013 in maternity and children's health care centers in zhuhai as the research objects, respectively took related questionnaire in pregnancy period of early,middle and late,then collected the results of the survey and statistical analysis. Results (1) The time of pregnant women continued standing and sitting in the early stages of pregnancy time was significantly reduced,the population distribution in different age,culture level and economic income had significant differences (P < 0.05).(2)The high degree of culture for pregnant women was the protection factor in gestational hypertension;The culture degree and the family economic income of pregnant women were the protection factor in gestational anemia;Older was a risk factor for gestational diabetes.(3)The incidence of hypertension and anemia were positively correlated with women sedentary long. Conclusion Standing long time in pregnancy period can increase the danger of high blood pressure,diabetes and anemia of pregnant women.%目的：调查研究孕早期的职业站立时间以及长时间站立对妊娠并发症的影响。方法分别对我市妇幼保健院2010年1月～2013年5月间建卡并分娩的460例妊娠妇女怀孕早期、中期和晚期进行相关问卷调查并进行统计学分析。结果（1）孕妇在孕早期的持续站立和坐着的时间均较孕前显著降低，其人群分布在不同年龄、文化程度和经济收入方面具有明显差异（P＜0.05）。（2）孕妇文化程度高是妊娠期高血压的保护因素；孕妇文化程度和家庭经济收入是妊娠贫血的保护因素；年龄较大是妊娠糖尿病的危险因素。（3）妊娠高血压和贫血的发病率与孕妇久坐久站呈正相关。结论孕前久站久坐可增加孕妇病发
Institute of Scientific and Technical Information of China (English)
王智勇
2014-01-01
Based on the requirement of high-power linear propulsion system, the short-time periodic linear induction motor ( LIM) needs to be designed. Based on thermal network, taking into account the end-winding and the effects of thermal conduction composite materials, the calculation method of the linear induction motor temperature field was proposed. The thermal network model of the temperature field of the periodic transient LIM was deduced. The rule of the LIM coil temperature change was obtained accurately. The simulation model was established based on the mathematical model, and then the performance of the motor thermal dissipation was simulated, which provided an important reference for the design and performance analysis of the linear induction motor.%基于大功率直线推进的要求，设计短时周期工作的直线感应电机。提出了基于热网络法，计及端部绕组热传导、复合材料影响的直线电机温度场计算方法，推导了周期暂态工作的直线电机温度场热网络模型，得到了该直线电机线圈导体准确的温度变化规律。基于数学模型建立了仿真模型，对电机散热性能进行了仿真计算，为该直线感应电动机的设计和性能分析提供了重要参考。
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朱胜; 孙明轩; 何熊熊
2012-01-01
An adaptive controller is designed for a class of periodically time-varying systems with input backlash,when the periodical uncertainties can be parameterized.The unknown periodical parameters are expanded into a Fourier series;the coefficients of which and the unknown parameters of the backlash dynamics are estimated by using differential adaptive algorithms.A robust method is applied to eliminate the influences of truncation errors and bounded errors in the backlash model on the system performance.The sign function is replaced by the hyperbolic function to ensure the differentiability for the controller and to avoid the chattering.The introduction of △ functions ensures the boundedness for the parameter estimates and the asymptotical convergence for the desired trajectory.The theoretical analysis and the numerical experiment show that all the signals in the closed-loop system remain bounded.%针对一类输入含齿隙非线性动态特性的周期时变系统,在周期不确定性可时变参数化的条件下设计自适应控制器.对周期时变参数进行傅里叶级数展开,并采用微分自适应律估计未知傅里叶系数和齿隙动态特性参数,通过鲁棒方法消除截断误差和齿隙模型的有界误差项对系统性能的影响.采用双曲函数替代符号函数确保控制器可微,同时能有效抑制颤振.引入△函数,避免参数估计发散,并保证系统输出渐近跟踪理想轨迹.理论分析与仿真结果表明,闭环系统所有信号有界.
Institute of Scientific and Technical Information of China (English)
张安慧; 陶芳标; 严双琴; 徐叶清
2009-01-01
目的 探讨不同回顾时限对儿童青少年伤害流行病学调查结果的影响.方法 对马鞍山市4523名学生进行1年的伤害主动监测,各学校由校医或健康信息员每天收集学生伤害事件,监测时间为2007年11月1日至2008年10月31日.监测对象分成3组,每组分别采用不同的间隔时限进行伤害自我回顾性报告.结果 4523名学生,全年共发生伤害事件6350人次,总伤害事件年发生率为74.2%,男生发生率(78.6%)高于女生(70.0%),差异有统计学意义(P<0.01).间隔3个月一次的回顾性报告伤害年发生率减低0.02%,伤害次数减少19人次;间隔6个月一次的回顾性报告伤害年发生率减低0.02%,伤害次数减少58人次;12个月回顾性调查过去一年内伤害事件发生情况,伤害年发生率减低8.8%,伤害次数减少505人次,以3～6岁组和轻度及微小伤害减低更为显著.结论 间隔3个月一次和间隔6个月一次回顾性报告的伤害年发生率只有轻微减低,对伤害信息的获得较完整;12个月的回忆期限,低估了伤害的发生风险;儿童青少年伤害的回顾时限以6个月为宜.%Objective To analyze the influence of different recall time periods on epidemiological survey of injuries among children and adolescents. Methods A study on injuries for 12 months follow-up period was actively surveyed among 4523 pupils selected by cluster sampling from 12 kindergartens, 1 elementary school, 1 junior high school, 1 senior high school and 1 college in Maanshan city in November, 2007 to November, 2008. Injury events were actively surveyed by school doctors or class health workers simultaneously. Participants were divided into three groups, the first group including self-reported injuries by 3-months interval, the second group with self-recalled injuries by 6-months interval and the third group with self-reported injuries in the past 12 months. Validity and reliability of injuries between surveillance injuries and
Period-doubling cascades galore
Sander, Evelyn; Yorke, James A.
2009-01-01
The appearance of numerous period-doubling cascades is among the most prominent features of {\\bf parametrized maps}, that is, smooth one-parameter families of maps $F:R \\times {\\mathfrak M} \\to {\\mathfrak M}$, where ${\\mathfrak M}$ is a smooth locally compact manifold without boundary, typically $R^N$. Each cascade has infinitely many period-doubling bifurcations, and it is typical to observe -- such as in all the examples we investigate here -- that whenever there are any cascades, there are...
Institute of Scientific and Technical Information of China (English)
刘大江; 李新民; 祝岩
2016-01-01
目的 探讨风湿性二尖瓣狭窄行瓣膜外科置换手术时机的选择对患者围术期的影响.方法 回顾性分析2012年1月至2013年12月在沈阳军区总医院心血管外科诊断为风湿性二尖瓣狭窄(MS)并行瓣膜置换的住院患者122例.根据术前心脏超声结果,按照二尖瓣瓣口面积(MVA)狭窄程度将患者分为三组,分别为轻度狭窄(＞1.5 cm2)、中度狭窄(1.0～1.5 cm2)和重度狭窄(＜1.0 cm2)组.收集患者的相关临床资料,通过单因素和多因素Logistic回归分析手术时机的选择对各组患者围术期的影响.结果 全组患者均取得理想效果,心功能等级与术前相比有较大的提升,患者生活质量得到改善.住院期间死亡2例,其余患者出院时纽约心功能等级(NYHA)都达到Ⅰ～Ⅱ、Ⅱ级之间,甚至Ⅰ级.单因素分析显示患者的肺动脉压力(PASP)、左室舒张末容积、二尖瓣口面积、心胸比、ICU时间、呼吸机辅助时间、住院时间为风湿性二尖瓣狭窄围术期预后的影响因素,多因素Logistic回归分析显示三组患者的肺动脉压力、二尖瓣口面积为风湿性二尖瓣狭窄围术期预后的独立影响因素.结论 二尖瓣置换术(MVR)是治疗风湿性二尖瓣狭窄的有效方法.适时地手术时机可以提高患者的围术期效果,有助于及早的改善生活质量.患者早期就诊也应当是影响围术期预后的重要因素.适时地手术时机、早期就诊可提高患者的围术期生存优势.%Objective To investigate the effect of operation timing on patients with rheumatic mitral stenosis underwent valve replacement during perioperative period.Methods Retrospective analysis were performed on 122 cases diagnosed as rheumatic mitral stenosis (mitral stenosis,MS) underwent valve replacement,during January 2012 through December 2013 in the Department of Cardiovascular Surgery,General Hospital of Shenyang military region.According to the mitral valve area (mitral
Inverse periodic shadowing properties
Osipov, Alexey V
2011-01-01
We consider inverse periodic shadowing properties of discrete dynamical systems generated by diffeomorphisms of closed smooth manifolds. We show that the $C^1$-interior of the set of all diffeomorphisms having so-called inverse periodic shadowing property coincides with the set of $\\Omega$-stable diffeomorphisms. The equivalence of Lipschitz inverse periodic shadowing property and hyperbolicity of the closure of all periodic points is proved. Besides, we prove that the set of all diffeomorphisms that have Lipschitz inverse periodic shadowing property and whose periodic points are dense in the nonwandering set coincides with the set of Axiom A diffeomorphisms.
Energy Technology Data Exchange (ETDEWEB)
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.
Directory of Open Access Journals (Sweden)
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.
Institute of Scientific and Technical Information of China (English)
LU WENLIAN; CHEN TIANPING
2004-01-01
The authors investigate the existence and the global stability of periodic solution for dynamical systems with periodic interconnections, inputs and self-inhibitions. The model is very general, the conditions are quite weak and the results obtained are universal.
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…
Community College Periodicals.
Pederson, Eldor O.
Drawing from an examination of community college periodicals, their availability and characteristics, the academic affiliations of contributing authors, and the topics of their articles, this paper discusses the minor role which community college periodicals appear to play. A list of 35 periodicals dealing primary with community college education…
Autism: a "critical period" disorder?
LeBlanc, Jocelyn J; Fagiolini, Michela
2011-01-01
Cortical circuits in the brain are refined by experience during critical periods early in postnatal life. Critical periods are regulated by the balance of excitatory and inhibitory (E/I) neurotransmission in the brain during development. There is now increasing evidence of E/I imbalance in autism, a complex genetic neurodevelopmental disorder diagnosed by abnormal socialization, impaired communication, and repetitive behaviors or restricted interests. The underlying cause is still largely unknown and there is no fully effective treatment or cure. We propose that alteration of the expression and/or timing of critical period circuit refinement in primary sensory brain areas may significantly contribute to autistic phenotypes, including cognitive and behavioral impairments. Dissection of the cellular and molecular mechanisms governing well-established critical periods represents a powerful tool to identify new potential therapeutic targets to restore normal plasticity and function in affected neuronal circuits.
Institute of Scientific and Technical Information of China (English)
樊连梅; 王超; 刘更森; 原永兵
2014-01-01
苹果果实着色期基因表达水平的变化对果实品质形成具有重要影响,选择适合的内参基因是提高实时荧光定量PCR分析准确性的首要条件。本试验以‘富士’苹果着色过程中不同取样时间的果皮为材料,通过qRT-PCR分析了常用候选持家基因β-actin、EF-1α、GAPDH和18S rRNA的表达变化,借助geNorm和NormFinder程序筛选出在果实着色期qRT-PCR分析的理想内参基因。结果表明, EF-1α的表达水平高且最稳定,其次是18S rRNA,而β-actin和GAPDH的相对表达水平较低；同时,用筛选的内参基因EF-1α和18S rRNA分析苹果花青苷合成途径的二氢黄酮醇-4-还原酶基因的表达水平,其表达规律比较一致,均呈现正态分布。因此, EF-1α和18S rRNA是研究苹果着色期表达的理想的内参基因。%The change of gene expression level during coloring period is crucial for the formation of apple fruit quality. The selection of a suitable reference gene is an important factor for accurate gene expression analysis by real-time lfuorescence quantitative PCR (qRT-PCR). In this study, peels of apple (Malus domestica cv.‘Fuji’) were taken as materials sampled at different time during coloring stage. The expression level of four commonly used housekeeping genesβ-actin, EF-1α, GAPDH and 18S rRNA were studied by qRT-PCR, and reliable refer-ence gene were screened to use for gene expression during coloring stage of fruit by geNorm and NormFinder software. The results showed that the expression level of EF-1αwas highest and most stable, followed by 18S rRNA. However, the expression level ofβ-actin and GAPDH were relatively low. Meanwhile, the expression of lfavonoid-4-reductase gene (MdDFR) in the pathway of apple anthocyanin biosynthesis was analyzed, and the results indicated that the variation tendency of MdDFR was exactly consistent and presented normal distribu-tion using EF-1αand 18S rRNA as reference gene. Therefore, EF-1αand 18S r
Akbarabadi, M Afsari; Shabankareh, H Karami; Abdolmohammadi, A; Shahsavari, M H
2014-08-01
This study was designed to evaluate the reproductive performance of lactating dairy cows (Holstein Friesian) after the injection of PGF2α analogue on Day 15 postpartum, and GnRH analogue on Day 23 after artificial insemination (AI) with Presynch (two injections of PGF2α, administered 14 days apart starting at 30-35 days postpartum) + Ovsynch-based (GnRH-7 days-PGF2α-2 days-GnRH-16-20 hours-timed artificial insemination) treatments, during the warm and cold periods of the year. All the cows (n = 313) were assigned to one of the four groups including: M1 (n = 72) in which the cows were treated with PGF2α on Day 15 postpartum + Presynch-Ovsynch + GnRH on Day 23 post-AI; M2 (n = 41) in which the cows received PGF2α on Day 15 postpartum + Presynch-Ovsynch; M3 (n = 100) including the cows that got Presynch-Ovsynch; and control group (n = 100) including the cows that were not treated and were inseminated at natural estrus. Pregnancy diagnosis was performed 28 to 35 days post-insemination by means of ultrasound. The results showed that treatment with PGF2α on Day 15 postpartum significantly decreased the days to conception and the number of services per conception (P 0.05). In contrast, administration of GnRH on Day 23 post-AI increased the days to conception and the number of service per conception (P artificial insemination after Presynch-Ovsynch protocol but also reduced that.
Institute of Scientific and Technical Information of China (English)
熊浩; 鄢慧丽; 周和平; 柳伍生
2013-01-01
针对多阶段动态车辆路径单决策和多决策问题,分别提出了平均距离策略和分区分批旅行商策略.前者优先安排不能延迟的顾客,然后根据路径的平均顾客距离选择可延迟顾客；后者根据阶段内决策的时间界限只在最后一次决策才考虑拒绝和延迟,实例仿真结果表明,新策略都具有较好的优化效果.%The multi-period dynamic vehicle routing problem(MPDVRP) belongs to the emerging problem of dynamic vehicle routing problem, which can be divided into single decision-making problem and multi-decision-making problem. Average distance strategy and cutting-and-batch TSP strategy were constructed for these two types of problems. The average distance strategy gives priority to customers those cannot be delayed, and then selects the customers those can be delayed according to the average path distance. In cutting-and-batch TSP strategy, the customers will be delayed or refused only in the last decision according to decision-making time limit. Simulations of the two strategies were carried out, and the numerical results show that the two strategies are both better than the existing strategies.
Energy Technology Data Exchange (ETDEWEB)
Junge, K.; Telljohann, U.
2004-04-15
Dryers of the brick industry are constructed according to empirical findings. Measurements are available only for the first drying period, the rest is speculation. The author investigated the processes going on inside the green brick during drying. This will provide the basis for a simulation program for calculating time-dependent moisture distributions, vibrational states and green brick temperatures, from which the required dryer air conditions and heat transfer processes can be derived. Brick producers and plant constructors will be enabled to design the drying process for high-speed drying without loss of quality and with higher economic efficiency. (orig.) [German] Die Auslegung von Trocknern der Ziegelindustrie und verwandter Branchen basiert bis heute ausschliesslich auf empirischen Erkenntnissen. Diese werden durch wissenschaftliche Arbeiten lediglich zum ersten Trocknungsabschnitt gestuetzt. Eine in Betriebsablaeufe integrierte messtechnische Erfassung des Uebergangs vom ersten zum zweiten Trocknungsabschnitt ist nicht moeglich. Fachleute schaetzen, dass der Uebergang 'etwa zur halben Anfangsfeuchte' stattfindet; diese Annahme ist jedoch aeusserst ungenau. Man unterstellt ferner, dass der erste Trocknungsabschnitt ungefaehr mit dem Zeitraum uebereinstimmt, in dem sich die mit erheblichen Riss- und Verkruemmungsgefaehrdungen einhergehende Rohlingsschwindung abspielt. Im Rahmen dieser Arbeit wird ein mathematisches Modell der Vorgaeng erstellt, die sich im Rohling waehrend der Trocknung abspielen. Es bildet die Grundlage fuer ein Simulationsprogramm zur Berechnung von zeitabhaengigen Feuchteverteilungen, Schwindungszustaenden und Rohlingstemperaturen. Daraus lassen sich dann fuer den Betrieb die notwendigen Trocknerluftzustaende und Waermeuebergaenge ermitteln. Diese Daten versetzen Ziegler und insbesondere Anlagenbauer in die Lage, den Trocknungsprozess verlaesslich so zu gestalten, dass Ziegelrohlinge ohne Qualitaetsmangel mit hoechstmoeglicher
Institute of Scientific and Technical Information of China (English)
汪灏; 李森恺; 杨明勇; 李养群; 李强; 王伊宁; 鲍世威
2012-01-01
Objective To study the changes of muscle being injected with botulinum toxin A in different period of time,helping for chemically denervated muscle transplantation.Methods Sixteen rabbits were divided into 4 groups.The extensor carpi radialis muscle in one side was chosen for experimental group with the opposite muscle for control group.Morphological changes,histological changes and electron microscopic changes of muscle being injected with botulinum toxin A were observed from the first week to the fouth week.Results The quantity of glycogen and mitochondria in the muscles reduced in the first week.But it was obvious in the third week.We also found some necrotic areas in the fouth week with the muscles restoring.Conclusions The effect of metabolism slowing down and the volume of muscle reducing after botulinum toxin A injection is obvious in third weeks.It could help us choose the best time of chemically denervated muscle transplantation.%目的 通过对A型肉毒毒素肌内注射后不同时间段肌肉的改变进行观察,了解肉毒毒素对肌肉的改变过程,并为化学去神经肌肉游离移植提供理论依据.方法 对16只活体兔桡侧腕伸肌进行肉毒毒素注射,分为4组(即1、2、3、4周组),每组4个肌肉,躯体对侧作为对比.分别在注射后1～4周进行大体观察,以及组织学和电镜观察.结果 药物注射后1周,肌内酶、糖原和线粒体都开始减少,体积的减少在3周左右明显,4周后肌酶的减少更加明显,并且内部区域有坏死灶,但体积较前有所恢复.结论 A型肉毒毒素肌内注射后可以减缓肌肉代谢和缩小肌肉体积,其中以第3周最为明显,可以为化学去神经肌肉游离移植的时间选择提供参考.
32 CFR 552.80 - Suspension period.
2010-07-01
... 32 National Defense 3 2010-07-01 2010-07-01 true Suspension period. 552.80 Section 552.80 National... Suspension period. All solicitation privileges suspended by installation commanders will be for a specific time. Normally, it will not exceed 2 years. When the suspension period expires, the agent may...
Periodic solutions of nonlinear vibrating beams
Directory of Open Access Journals (Sweden)
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.
Bott periodicity of inclusions
Mare, Augustin-Liviu
2011-01-01
When looking at Bott's original proof of his periodicity theorem for the stable homotopy groups of the orthogonal and unitary groups, one sees in the background a differential geometric periodicity phenomenon. We show that this geometric phenomenon extends to the standard inclusion of the orthogonal group into the unitary group. This explains the periodicity of the group homomorphisms between stable homotopy groups which are induced by the inclusion map. Standard inclusions between other classical Riemannian symmetric spaces are also discussed.
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.
Morre, D. James; Lawler, Juliana; Wang, Sui; Keenan, Thomas W.; Morre, Dorothy M.
2002-01-01
Entrainment in solution of an oscillating activity with a temperature compensated period of 24 min is described for a NADH oxidase (NOX) activity of the bovine milk fat globule membrane, a derivative of the mammary epithelial cell plasma membrane. The period of 24 min remained unchanged at 17 degrees C, 27 degrees C and 37 degrees C whereas the amplitude approximately doubled with each 10 degree C rise in temperature (Q(10)congruent with 2). The periodicity was observed with both intact milk fat globule membranes and with detergent-solubilized membranes, demonstrating that the oscillations did not require an association with membranes. The periodicity was not the result of instrument variation or of chemical interactions among reactants in solution. Preparations with different periodicities entrained (autosynchronized) when mixed. Upon mixing, the preparations exhibited two oscillatory patterns but eventually a single pattern representing the mean of the farthest separated maxima of the two preparations analyzed separately emerged. The cell surface NOX protein is the first reported example of an entrainable biochemical entity with a temperature-compensated periodicity potentially capable of functioning as an ultradian or circadian clock driver.
Institute of Scientific and Technical Information of China (English)
陈素君; 谢冬梅; 廖丽梅; 黄勇华; 王艳清; 田桂敏; 黎文思; 邓启健; 朱敏捷
2016-01-01
Objective To Analysis of the changes of the effective components of MB-P fresh plasma and fresh plasma in different time in the preservation period ,provides the reference for the clinical infusion .Methods Taken 20 doses of whole blood (400 mL/copy) ,in accordance with standard operating procedures preparation fresh plasma (200 mL/copy);Split them in two parts and di-vided into virus inactivated plasma and fresh plasma group ,and divided this two kinds of plasmar in five equal parts in aseptic pack-aging each;immediately put them into a refrigerator for quick-frozen .Detected their Ⅴ factor ,Ⅷ factor ,Fib ,methylene blue resi-dues ,total protein ,pH value ,the content of K+ ,Na+ and Cl- after 0 (less than 72 h after preparation) ,3 ,6 ,9 and 12 months re-spectively .Results Two kinds of plasma with the extension of the storage period ,Ⅴ factor ,Ⅷ factor ,Fib ,total protein ,K+ ,Na+ , Cl- levels were decreased ,pH showed an upward trend ,the difference was statistically significant (P<0 .05) .Conclusion After vi-rus inactivation treatment ,the level of plasma constituents have been changed ,but to conform to the standard of blood for clinical use .Therefore ,the virus inactivation treatment could be used to improve the safety of the effective components of plasma .%目的 分析亚甲蓝光化学法(MB-P )灭活处理新鲜血浆(简称病毒灭活新鲜血浆)与未经灭活处理的新鲜血浆(简称新鲜血浆)在保存期内不同时间段有效成分的变化 ,为临床输注提供参考依据.方法 取20人份全血(每份400 m L ) ,按照标准操作规程制备成新鲜血浆(每份200 m L )后 ,将其一分为二 ,制备病毒灭活新鲜血浆和新鲜血浆 ,两种血浆每份无菌分装为5等份 ,立即放入速冻冰箱速冻 ,在0(制备后小于72 h)、3、6、9、12个月分别检测Ⅴ因子、Ⅷ因子、纤维蛋白原(Fib)、亚甲蓝残留量、总蛋白、pH值、K+ 、Na+ 、Cl-水平.结果 两种
Directory of Open Access Journals (Sweden)
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
Menstruation - painful; Dysmenorrhea; Periods - painful; Cramps - menstrual; Menstrual cramps ... related activities for a few days during each menstrual cycle. Painful menstruation is the leading cause of ...
Prediction Theory of Periodically Correlated Stochastic Processes
2015-05-12
in order to do a reliable forecasting of periodically correlated sequences with large period (or continuous time processes) the standard method of...aimed at sequences with large periods. It has been known already for years that in order to do a reliable forecasting of periodically correlated...we showed that this technique is very efficient. We successfully used it to study structure, regularity, autoregressive representation, innovation
[Childhood periodic syndromes].
Cuvellier, J-C; Lépine, A
2010-01-01
This review focuses on the so-called "periodic syndromes of childhood that are precursors to migraine", as included in the Second Edition of the International Classification of Headache Disorders. Three periodic syndromes of childhood are included in the Second Edition of the International Classification of Headache Disorders: abdominal migraine, cyclic vomiting syndrome and benign paroxysmal vertigo, and a fourth, benign paroxysmal torticollis is presented in the Appendix. The key clinical features of this group of disorders are the episodic pattern and intervals of complete health. Episodes of benign paroxysmal torticollis begin between 2 and 8 months of age. Attacks are characterized by an abnormal inclination and/or rotation of the head to one side, due to cervical dystonia. They usually resolve by 5 years. Benign paroxysmal vertigo presents as sudden attacks of vertigo, accompanied by inability to stand without support, and lasting seconds to minutes. Age at onset is between 2 and 4 years, and the symptoms disappear by the age of 5. Cyclic vomiting syndrome is characterized in young infants and children by repeated stereotyped episodes of pernicious vomiting, at times to the point of dehydration, and impacting quality of life. Mean age of onset is 5 years. Abdominal migraine remains a controversial issue and presents in childhood with repeated stereotyped episodes of unexplained abdominal pain, nausea and vomiting occurring in the absence of headache. Mean age of onset is 7 years. Both cyclic vomiting syndrome and abdominal migraine are noted for the absence of pathognomonic clinical features but also for the large number of other conditions to be considered in their differential diagnoses. Diagnostic criteria, such as those of the Second Edition of the International Classification of Headache Disorders and the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition, have made diagnostic approach and management easier. Their diagnosis
A new pattern of the periodic table
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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.
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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.
DEFF Research Database (Denmark)
Maisondieu, Christophe; Giebhardt, Jochen; Tetu, Amelie
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....
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…
DEFF Research Database (Denmark)
Sorokin, Sergey V.
2015-01-01
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 o...
Kobayashi, M; Irisawa, H
1961-10-27
The latent period of relaxation of molluscan myocardium due to anodal current is much longer than that of contraction. Although the rate and the grade of relaxation are intimately related to both the stimulus condition and the muscle tension, the latent period of relaxation remains constant, except when the temperature of the bathing fluid is changed.
Huber, Annette
2017-01-01
This book casts the theory of periods of algebraic varieties in the natural setting of Madhav Nori’s abelian category of mixed motives. It develops Nori’s approach to mixed motives from scratch, thereby filling an important gap in the literature, and then explains the connection of mixed motives to periods, including a detailed account of the theory of period numbers in the sense of Kontsevich-Zagier and their structural properties. Period numbers are central to number theory and algebraic geometry, and also play an important role in other fields such as mathematical physics. There are long-standing conjectures about their transcendence properties, best understood in the language of cohomology of algebraic varieties or, more generally, motives. Readers of this book will discover that Nori’s unconditional construction of an abelian category of motives (over fields embeddable into the complex numbers) is particularly well suited for this purpose. Notably, Kontsevich's formal period algebra represents a to...
Periodic Sweep Coverage Scheme Based on Periodic Vehicle Routing Problem
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Li Shu
2014-03-01
Full Text Available We provide a sweep coverage algorithm for routing mobile sensors that communicate with a central data sink. This algorithm improves on its predecessors by reducing the number of unnecessary scans when different points of interest (POIs have different requirements for the time interval within which they must be scanned (sweep period. Most sweep coverage algorithms seek to minimize the number of sensors required to cover a given collection of POIs. When POIs have different sweep period requirements, existing algorithms will produce solutions in which sensors visit some POIs much more frequently than is necessary. We define this as the POI Over-Coverage problem. In order to address this problem we develop a Periodic Sweep Coverage (PSC scheme based on a well-known solution to the Periodic Vehicle Routing Problem (PVRP. Our algorithm seeks a route for the mobile sensors that minimizes the number of unnecessary visits to each POI. To verify and test the proposed scheme we implemented a C++ simulation and ran scenarios with a variety of POI topologies (number and distribution of the POIs and the speed at which sensors could travel. The simulation results show that the PSC algorithm outperforms other sweep coverage algorithms such as CSweep and Vehicle Routing Problem Sweep Coverage (VRPSC on both the average number of sensors in a solution and in the computational time required to find a solution. Our results also demonstrate that the PSC scheme is more suitable for the sweep coverage scenarios in which higher speed mobile sensors are used.
Periodicity, the Canon and Sport
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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.
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Carlos A. Berenstein
1980-01-01
Full Text Available We show that any mean-periodic function f can be represented in terms of exponential-polynomial solutions of the same convolution equation f satisfies, i.e., u∗f=0(μ∈E′(ℝn. This extends to n-variables the work of L. Schwartz on mean-periodicity and also extends L. Ehrenpreis' work on partial differential equations with constant coefficients to arbitrary convolutors. We also answer a number of open questions about mean-periodic functions of one variable. The basic ingredient is our work on interpolation by entire functions in one and several complex variables.
Institute of Scientific and Technical Information of China (English)
秦辛玲; 石青峰
2015-01-01
目的：探讨高泌乳素血症患者泌乳素水平在不同时间段的变化。方法使用电化学发光法、罗氏 E170全自动免疫分析仪测定124例高泌乳素（PRL＞880 uIU／ml），女性患者在7：30AM，10：00AM及4：00PM不同时间段血浆泌乳素（PRL）水平，并根据经聚乙二醇（PEG）6000沉淀巨泌乳素后的 PRL回收率分成巨泌乳素组（回收率≤40％）、单泌乳素组（回收率＞60％）、可疑泌乳素组（40％＜回收率≤60％），同时检测45例正常对照组的PRL水平。结果高泌乳素组巨泌乳素阳性率（33.1％）与正常对照组中巨泌乳素阳性率（0.0％）比较，差异有统计学意义（χ2＝17.8867，P＜0.05），巨泌乳素组及单体泌乳素组经PEG处理前在10：00AM时间段的泌乳素浓度（1160±714 uIU／ml，885±801 uIU／ml）与7：30AM时间段的泌乳素浓度（1521±914 uIU／ml，1497±845 uIU／ml）差异均有统计学意义（t＝1.993，4.46，P＜0.05），巨泌乳素组及单体泌乳素组经PEG处理后在10：00AM时间段的泌乳素浓度（316±231 uIU／ml，766±611 uIU／ml）与7：30AM时间段的泌乳素浓度（488±394 uIU／ml，1235±912 uIU／ml）差异均有统计学意义（t＝2.4114，3.6252，P＜0.05），单泌乳素组4：00PM时间段处理前的泌乳素浓度（1033±911 uIU／ml）与7：30AM时间段处理前的泌乳素浓度（1497±845 uIU／ml）差异也有统计学意义（t＝3.1686，P＜0.05）。结论不同时间段泌乳素水平有变化，确定正确的采血时间，有助于临床对高泌乳素血症的诊断。%Objective To investigate prolactin(PRL)levels in patient with hyperprolactinemia in different period of time. Methods Used electrochemical luminescence method,Roche E170 automatic immune analyzer determination of detect 124 cases female patients of hyperprolactinemia (PRL>880 uIU/ml)at 7:30AM,10:00AM and 4:00PM respectivelye of plas-ma PRL level,and in accordance
Colonius, Fritz
1988-01-01
This research monograph deals with optimal periodic control problems for systems governed by ordinary and functional differential equations of retarded type. Particular attention is given to the problem of local properness, i.e. whether system performance can be improved by introducing periodic motions. Using either Ekeland's Variational Principle or optimization theory in Banach spaces, necessary optimality conditions are proved. In particular, complete proofs of second-order conditions are included and the result is used for various versions of the optimal periodic control problem. Furthermore a scenario for local properness (related to Hopf bifurcation) is drawn up, giving hints as to where to look for optimal periodic solutions. The book provides mathematically rigorous proofs for results which are potentially of importance in chemical engineering and aerospace engineering.
Extremal periodic wave profiles
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E. van Groesen
2007-01-01
Full Text Available As a contribution to deterministic investigations into extreme fluid surface waves, in this paper wave profiles of prescribed period that have maximal crest height will be investigated. As constraints the values of the momentum and energy integrals are used in a simplified description with the KdV model. The result is that at the boundary of the feasible region in the momentum-energy plane, the only possible profiles are the well known cnoidal wave profiles. Inside the feasible region the extremal profiles of maximal crest height are "cornered" cnoidal profiles: cnoidal profiles of larger period, cut-off and periodically continued with the prescribed period so that at the maximal crest height a corner results.
Avram, A C; Jancic, D; Uni, H; Uni, Humboldt
1995-01-01
The periods of the three-form on a Calabi-Yau manifold are found as solutions of the Picard-Fuchs equations; however, the toric varietal method leads to a generalized hypergeometric system of equations which has more solutions than just the periods. This same extended set of equations can be derived from symmetry considerations. Semi-periods are solutions of this extended system. They are obtained by integration of the three-form over chains; these chains can be used to construct cycles which, when integrated over, give periods. In simple examples we are able to obtain the complete set of solutions for the extended system. We also conjecture that a certain modification of the method will generate the full space of solutions in general.
... and less severe than the hypokalemic form. Muscle spasms are common. × Definition Familial periodic paralyses are a ... and less severe than the hypokalemic form. Muscle spasms are common. View Full Definition Treatment Treatment of ...
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)
Exploration of Periodically Varying Graphs
Flocchini, Paola; Santoro, Nicola
2009-01-01
We study the computability and complexity of the exploration problem in a class of highly dynamic graphs: periodically varying (PV) graphs, where the edges exist only at some (unknown) times defined by the periodic movements of carriers. These graphs naturally model highly dynamic infrastructure-less networks such as public transports with fixed timetables, low earth orbiting (LEO) satellite systems, security guards' tours, etc. We establish necessary conditions for the problem to be solved. We also derive lower bounds on the amount of time required in general, as well as for the PV graphs defined by restricted classes of carriers movements: simple routes, and circular routes. We then prove that the limitations on computability and complexity we have established are indeed tight. In fact we prove that all necessary conditions are also sufficient and all lower bounds on costs are tight. We do so constructively presenting two worst case optimal solution algorithms, one for anonymous systems, and one for those w...
Social Research On Renaissance Period
Institute of Scientific and Technical Information of China (English)
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.
Correspondence Between Astronomical Periods and Sedimentary Cycles
Institute of Scientific and Technical Information of China (English)
Cheng Rihui; You Haitao
2000-01-01
It is shown from detailed study that there are some genetic relationships between outer events of celestial bodies and inner geological events of the earth, such as some kinds of correspondences between astronomical periods and sedimentary cycles. The time spans of movement periods of the solar system around the center of the galaxy and cross the plain of the galaxy, the periods of the earth orbit (Milankovitch period) and periods of sunspot are coincided with that of respective sedimentary cycles. It is suggested that the gravity and magnetic changes of the earth leading up to the global climatic and sea level changes are the dynamics of sedimentary cycles.
Directory of Open Access Journals (Sweden)
Rojith Karandode Balakrishnan
2011-01-01
Full Text Available This article aims at highlighting the importance of suspecting thyrotoxicosis in cases of recurrent periodic flaccid paralysis; especially in Asian men to facilitate early diagnosis of the former condition. A case report of a 28 year old male patient with recurrent periodic flaccid paralysis has been presented. Hypokalemia secondary to thyrotoxicosis was diagnosed as the cause of the paralysis. The patient was given oral potassium intervention over 24 hours. The patient showed complete recovery after the medical intervention and was discharged after 24 hours with no residual paralysis. Thyrotoxic periodic paralysis (TPP is a complication of thyrotoxicosis, more common amongst males in Asia. It presents as acute flaccid paralysis in a case of hyperthyroidism with associated hypokalemia. The features of thyrotoxicosis may be subtle or absent. Thus, in cases of recurrent or acute flaccid muscle paralysis, it is important to consider thyrotoxicosis as one of the possible causes, and take measures accordingly.
Hystad, Grethe
2010-01-01
In this paper, we first rework B. Kaufman's 1949 paper, "Crystal Statistics. II. Partition Function Evaluated by Spinor Analysis", by using representation theory. Our approach leads to a simpler and more direct way of deriving the spectrum of the transfer matrix for the finite periodic Ising model. We then determine formulas for the spin correlation functions that depend on the matrix elements of the induced rotation associated with the spin operator in a basis of eigenvectors for the transfer matrix. The representation of the spin matrix elements is obtained by considering the spin operator as an intertwining map. We exhibit the "new" elements V+ and V- in the Bugrij-Lisovyy formula as part of a holomorphic factorization of the periodic and anti-periodic summability kernels on the spectral curve associated with the induced rotation for the transfer matrix.
Soliton Management in Periodic Systems
Malomed, Boris A
2006-01-01
During the past ten years, there has been intensive development in theoretical and experimental research of solitons in periodic media. This book provides a unique and informative account of the state-of-the-art in the field. The volume opens with a review of the existence of robust solitary pulses in systems built as a periodic concatenation of very different elements. Among the most famous examples of this type of systems are the dispersion management in fiber-optic telecommunication links, and (more recently) photonic crystals. A number of other systems belonging to the same broad class of spatially periodic strongly inhomogeneous media (such as the split-step and tandem models) have recently been identified in nonlinear optics, and transmission of solitary pulses in them was investigated in detail. Similar soliton dynamics occurs in temporal-domain counterparts of such systems, where they are subject to strong time-periodic modulation (for instance, the Feshbach-resonance management in Bose-Einstein conde...
Quantifying Periodicity in Omics Data
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Cornelia eAmariei
2014-08-01
Full Text Available Oscillations play a significant role in biological systems, with many examples in the fast, ultradian, circadian, circalunar and yearly time domains. However, determining periodicity in such data can be problematic. There are a number of computational methods to identify the periodic components in large datasets, such as signal-to-noise based Fourier decomposition, Fisher's g-test and autocorrelation. However, the available methods assume a sinusoidal model and do not attempt to quantify the waveform shape and the presence of multiple periodicities, which provide vital clues in determining the underlying dynamics. Here, we developed a Fourier based measure that generates a de-noised waveform from multiple significant frequencies. This waveform is then correlated with the raw data from the respiratory oscillation found in yeast, to provide oscillation statistics including waveform metrics and multi-periods. The method is compared and contrasted to commonly used statistics. Moreover we show the utility of the program in the analysis of noisy datasets and other high-throughput analyses, such as metabolomics and flow cytometry, respectively.
Hon, Nick K.; Tsia, Kevin K.; Solli, Daniel R.; Khurgin, Jacob B.; Jalali, Bahram
2010-02-01
Bulk centrosymmetric silicon lacks second-order optical nonlinearity χ(2) - a foundational component of nonlinear optics. Here, we propose a new class of photonic device which enables χ(2) as well as quasi-phase matching based on periodic stress fields in silicon - periodically-poled silicon (PePSi). This concept adds the periodic poling capability to silicon photonics, and allows the excellent crystal quality and advanced manufacturing capabilities of silicon to be harnessed for devices based on χ(2)) effects. The concept can also be simply achieved by having periodic arrangement of stressed thin films along a silicon waveguide. As an example of the utility, we present simulations showing that mid-wave infrared radiation can be efficiently generated through difference frequency generation from near-infrared with a conversion efficiency of 50% based on χ(2) values measurements for strained silicon reported in the literature [Jacobson et al. Nature 441, 199 (2006)]. The use of PePSi for frequency conversion can also be extended to terahertz generation. With integrated piezoelectric material, dynamically control of χ(2)nonlinearity in PePSi waveguide may also be achieved. The successful realization of PePSi based devices depends on the strength of the stress induced χ(2) in silicon. Presently, there exists a significant discrepancy in the literature between the theoretical and experimentally measured values. We present a simple theoretical model that produces result consistent with prior theoretical works and use this model to identify possible reasons for this discrepancy.
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…
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
Chandramouli, V. V. M. S.; Martens, M.; De Melo, W.; Tresser, C. P.
2009-01-01
The period doubling renormalization operator was introduced by Feigenbaum and by Coullet and Tresser in the 1970s to study the asymptotic small-scale geometry of the attractor of one-dimensional systems that are at the transition from simple to chaotic dynamics. This geometry turns out not to depend
de Avellar, M. G. B.; Méndez, M.; Sanna, A.; Horvath, J. E.
2014-01-01
We studied the time lags and the coherence of the X-ray light curves of the neutron star low mass X-ray binaries 4U 1608-52 and 4U 1636-53. These quantities are frequency-dependent measures of the time or phase delay and of the degree of linear correlation between two X-ray light curves in two diffe
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.
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