Long-time data storage: relevant time scales
Elwenspoek, Miko C.
2011-01-01
Dynamic processes relevant for long-time storage of information about human kind are discussed, ranging from biological and geological processes to the lifecycle of stars and the expansion of the universe. Major results are that life will end ultimately and the remaining time that the earth is habit
Long-Time Data Storage: Relevant Time Scales
Miko C. Elwenspoek
2011-02-01
Full Text Available Dynamic processes relevant for long-time storage of information about human kind are discussed, ranging from biological and geological processes to the lifecycle of stars and the expansion of the universe. Major results are that life will end ultimately and the remaining time that the earth is habitable for complex life is about half a billion years. A system retrieved within the next million years will be read by beings very closely related to Homo sapiens. During this time the surface of the earth will change making it risky to place a small number of large memory systems on earth; the option to place it on the moon might be more favorable. For much longer timescales both options do not seem feasible because of geological processes on the earth and the flux of small meteorites to the moon.
Dynamic Leidenfrost effect: relevant time- and length-scales
Shirota, Minori; Sun, Chao; Prosperetti, Andrea; Lohse, Detlef
2015-01-01
When a liquid droplet impacts a hot solid surface, enough vapor may be generated under it as to prevent its contact with the solid. The minimum solid temperature for this so-called Leidenfrost effect to occur is termed the Leidenfrost temperature, or the dynamic Leidenfrost temperature when the droplet velocity is non-negligible. We observe the wetting/drying and the levitation dynamics of the droplet impacting on an (isothermal) smooth sapphire surface using high speed total internal reflection imaging, which enables us to observe the droplet base up to about 100 nm above the substrate surface. By this method we are able to reveal the processes responsible for the transitional regime between the fully wetting and the fully levitated droplet as the solid temperature increases, thus shedding light on the characteristic time- and length-scales setting the dynamic Leidenfrost temperature for droplet impact on an isothermal substrate.
Time series decomposition methods were applied to meteorological and air quality data and their numerical model estimates. Decomposition techniques express a time series as the sum of a small number of independent modes which hypothetically represent identifiable forcings, thereb...
Philip Coppens
2015-03-01
Full Text Available A number of examples illustrate structural-dynamics studies of picosecond and slower photo-induced processes. They include molecular rearrangements and excitations. The information that can be obtained from such studies is discussed. The results are complementary to the information obtained from femtosecond studies. The point is made that all pertinent time scales should be covered to obtain comprehensive insight in dynamic processes of chemical and biological importance.
Hallock, Michael J; Stone, John E; Roberts, Elijah; Fry, Corey; Luthey-Schulten, Zaida
2014-05-01
Simulation of in vivo cellular processes with the reaction-diffusion master equation (RDME) is a computationally expensive task. Our previous software enabled simulation of inhomogeneous biochemical systems for small bacteria over long time scales using the MPD-RDME method on a single GPU. Simulations of larger eukaryotic systems exceed the on-board memory capacity of individual GPUs, and long time simulations of modest-sized cells such as yeast are impractical on a single GPU. We present a new multi-GPU parallel implementation of the MPD-RDME method based on a spatial decomposition approach that supports dynamic load balancing for workstations containing GPUs of varying performance and memory capacity. We take advantage of high-performance features of CUDA for peer-to-peer GPU memory transfers and evaluate the performance of our algorithms on state-of-the-art GPU devices. We present parallel e ciency and performance results for simulations using multiple GPUs as system size, particle counts, and number of reactions grow. We also demonstrate multi-GPU performance in simulations of the Min protein system in E. coli. Moreover, our multi-GPU decomposition and load balancing approach can be generalized to other lattice-based problems.
Lunkenbein, Thomas; Girgsdies, Frank; Kandemir, Timur; Thomas, Nygil; Behrens, Malte; Schlögl, Robert; Frei, Elias
2016-10-01
Long-term stability of catalysts is an important factor in the chemical industry. This factor is often underestimated in academic testing methods, which may lead to a time gap in the field of catalytic research. The deactivation behavior of an industrially relevant Cu/ZnO/Al2 O3 catalyst for the synthesis of methanol is reported over a period of 148 days time-on-stream (TOS). The process was investigated by a combination of quasi in situ and ex situ analysis techniques. The results show that ZnO is the most dynamic species in the catalyst, whereas only slight changes can be observed in the Cu nanoparticles. Thus, the deactivation of this catalyst is driven by the changes in the ZnO moieties. Our findings indicate that methanol synthesis is an interfacially mediated process between Cu and ZnO.
Integral equations on time scales
Georgiev, Svetlin G
2016-01-01
This book offers the reader an overview of recent developments of integral equations on time scales. It also contains elegant analytical and numerical methods. This book is primarily intended for senior undergraduate students and beginning graduate students of engineering and science courses. The students in mathematical and physical sciences will find many sections of direct relevance. The book contains nine chapters and each chapter is pedagogically organized. This book is specially designed for those who wish to understand integral equations on time scales without having extensive mathematical background.
Cummins, D.J.F.
1985-01-01
This thesis seeks to extend the search for the moral implications inherent in the development, possession, and the threatened use of physical/astrophysical processes and in current understandings of the evolution of the physical universe. The nature of normal/theological discussion will not be a primary concern although clearly some residual position that such discussion is meaningful is presupposed. Neither is the nature of science or the scientific method at issue. It is assumed that both theology and science have long since negotiated the confidence crises of adolescence, and have mustered the requisite self-esteem regarding their respective disciplines. The aim of this work is to present the concept of time scales as a relevant moral category. It investigates the use of this concept and its relationship to the other categories developed in the relevant scientific literature. The question is raised as to the validity of and the future of the concept of time scales as a common moral ground.
Gallavotti, G
2006-06-01
Entropy creation rate is introduced for a system interacting with thermostats (i.e., for a system subject to internal conservative forces interacting with "external" thermostats via conservative forces) and a fluctuation theorem for it is proved. As an application, a time scale is introduced, to be interpreted as the time over which irreversibility becomes manifest in a process leading from an initial to a final stationary state of a mechanical system in a general nonequilibrium context. The time scale is evaluated in a few examples, including the classical Joule-Thompson process (gas expansion in a vacuum).
PHILOSOPHY IN CONTEMPORARY TIME: RELEVANCE VS ...
JONATHAN
philosophy has come to be perceived as having enjoyed its relevance in the past and ... students of philosophy do not understand what philosophy students do in their philosophy ..... interpersonal, inter-ethnic and international relationships.
Jensen's Functionals on Time Scales
Matloob Anwar
2012-01-01
Full Text Available We consider Jensen’s functionals on time scales and discuss its properties and applications. Further, we define weighted generalized and power means on time scales. By applying the properties of Jensen’s functionals on these means, we obtain several refinements and converses of Hölder’s inequality on time scales.
Pireaux, S
2007-01-01
The LISA mission is a space interferometer aiming at the detection of gravitational waves in the [$10^{-4}$,$10^{-1}$] Hz frequency band. In order to reach the gravitational wave detection level, a Time Delay Interferometry (TDI) method must be applied to get rid of (most of) the laser frequency noise and optical bench noise. This TDI analysis is carried out in terms of the coordinate time corresponding to the Barycentric Coordinate Reference System (BCRS), TCB, whereas the data at each of the three LISA stations is recorded in terms of each station proper time. We provide here the required proper time versus BCRS time transformation. We show that the difference in rate of station proper time versus TCB is of the order of $5 10^{-8}$. The difference between station proper times and TCB exhibits an oscillatory trend with a maximum amplitude of about $10^{-3}$ s.
Gradstein, F.M.; Ogg, J.G.; Hilgen, F.J.
2012-01-01
This report summarizes the international divisions and ages in the Geologic Time Scale, published in 2012 (GTS2012). Since 2004, when GTS2004 was detailed, major developments have taken place that directly bear and have considerable impact on the intricate science of geologic time scaling. Precam br
Measuring Biological Parameters in Rivers: Relevance of the Spatial Scale
Romani, A. M.
2009-07-01
The analyses of biological parameters in river ecosystems have been traditionally used as indicative of water quality with the advantage over chemical or physical analyses that they integrate the effects of punctual as well as long term effects. However, analyses of biological parameters (such as biomass and metabolism) performed at different spatial scales (from the microbial communities to the whole river) inform about different key processes. At the finer scale, microbial interactions and the structure of the microbial community (biofilm microbial biomass, three dimensional structure, and relevance of polysaccharide matrix) can be detected. At the reach scale, the different stream bed substrate (sediment, rocks, and particulate organic matter accumulation) are shown to play differential and specific roles on the processing of organic and inorganic materials in the flowing water. (Author)
Time Scale in Least Square Method
Özgür Yeniay
2014-01-01
Full Text Available Study of dynamic equations in time scale is a new area in mathematics. Time scale tries to build a bridge between real numbers and integers. Two derivatives in time scale have been introduced and called as delta and nabla derivative. Delta derivative concept is defined as forward direction, and nabla derivative concept is defined as backward direction. Within the scope of this study, we consider the method of obtaining parameters of regression equation of integer values through time scale. Therefore, we implemented least squares method according to derivative definition of time scale and obtained coefficients related to the model. Here, there exist two coefficients originating from forward and backward jump operators relevant to the same model, which are different from each other. Occurrence of such a situation is equal to total number of values of vertical deviation between regression equations and observation values of forward and backward jump operators divided by two. We also estimated coefficients for the model using ordinary least squares method. As a result, we made an introduction to least squares method on time scale. We think that time scale theory would be a new vision in least square especially when assumptions of linear regression are violated.
A Time scales Noether's theorem
Anerot, Baptiste; Cresson, Jacky; Pierret, Frédéric
2016-01-01
We prove a time scales version of the Noether's theorem relating group of symmetries and conservation laws. Our result extends the continuous version of the Noether's theorem as well as the discrete one and corrects a previous statement of Bartosiewicz and Torres in \\cite{BT}.
Integrable Equations on Time Scales
Gurses, Metin; Guseinov, Gusein Sh.; Silindir, Burcu
2005-01-01
Integrable systems are usually given in terms of functions of continuous variables (on ${\\mathbb R}$), functions of discrete variables (on ${\\mathbb Z}$) and recently in terms of functions of $q$-variables (on ${\\mathbb K}_{q}$). We formulate the Gel'fand-Dikii (GD) formalism on time scales by using the delta differentiation operator and find more general integrable nonlinear evolutionary equations. In particular they yield integrable equations over integers (difference equations) and over $q...
Extracting the relevant delays in time series modelling
Goutte, Cyril
1997-01-01
selection, and more precisely stepwise forward selection. The method is compared to other forward selection schemes, as well as to a nonparametric tests aimed at estimating the embedding dimension of time series. The final application extends these results to the efficient estimation of FIR filters on some......In this contribution, we suggest a convenient way to use generalisation error to extract the relevant delays from a time-varying process, i.e. the delays that lead to the best prediction performance. We design a generalisation-based algorithm that takes its inspiration from traditional variable...
Sørup, Hjalte Jomo Danielsen
Time series of precipitation are necessary for assessment of urban hydrological systems. In a changed climate this is challenging as climate model output is not directly comparable to observations at the scales relevant for urban hydrology. The focus of this PhD thesis is downscaling...... of precipitation to spatio-temporal scales used in urban hydrology. It investigates several observational data products and identifies relevant scales where climate change and precipitation can be assessed for urban use. Precipitation is modelled at different scales using different stochastic techniques. A weather...... generator is used to produce an artificial spatio-temporal precipitation product that can be used both directly in large scale urban hydrological modelling and for derivation of extreme precipitation statistics relevant for urban hydrology. It is discussed why precipitation time series from a changed...
Relevance of context and time-frame in bursty dynamics
Jo, Hang-Hyun; Perotti, Juan I; Kaski, Kimmo
2013-01-01
Inhomogeneous temporal processes in natural and social phenomena have been described by bursts that are rapidly occurring events within short periods alternating with long periods of low activity. Such a temporal process can be decomposed into sub-processes, according to the contexts, i.e. circumstances in which the events occur. Then contextual bursts for each sub-process are related to context-blind bursts for the original process. This requires to study contextual bursts in real time-frame as well as in ordinal time-frame, where the real timings of events are replaced by their orders in the event sequence. By analyzing a model of uncorrelated inter-event times we find that contextual bursts in real time-frame can be dominated by either context-blind bursts or contextual bursts in ordinal time-frame, or be characterized by both. These results on the relevance of context and time-frame give insight into the origin of bursts.
Relevant Spatial Scales of Chemical Variation in Aplysina aerophoba
Oriol Sacristan-Soriano
2011-11-01
Full Text Available Understanding the scale at which natural products vary the most is critical because it sheds light on the type of factors that regulate their production. The sponge Aplysina aerophoba is a common Mediterranean sponge inhabiting shallow waters in the Mediterranean and its area of influence in Atlantic Ocean. This species contains large concentrations of brominated alkaloids (BAs that play a number of ecological roles in nature. Our research investigates the ecological variation in BAs of A. aerophoba from a scale of hundred of meters to thousand kilometers. We used a nested design to sample sponges from two geographically distinct regions (Canary Islands and Mediterranean, over 2500 km, with two zones within each region (less than 50 km, two locations within each zone (less than 5 km, and two sites within each location (less than 500 m. We used high-performance liquid chromatography to quantify multiple BAs and a spectrophotometer to quantify chlorophyll a (Chl a. Our results show a striking degree of variation in both natural products and Chl a content. Significant variation in Chl a content occurred at the largest and smallest geographic scales. The variation patterns of BAs also occurred at the largest and smallest scales, but varied depending on which BA was analyzed. Concentrations of Chl a and isofistularin-3 were negatively correlated, suggesting that symbionts may impact the concentration of some of these compounds. Our results underline the complex control of the production of secondary metabolites, with factors acting at both small and large geographic scales affecting the production of multiple secondary metabolites.
Time scale of stationary decoherence
Polonyi, Janos
2017-07-01
The decoherence of a test particle interacting with an ideal gas is studied by the help of the effective Lagrangian, derived in the leading order of the perturbation expansion and in order O (∂t2) . The stationary decoherence time is found to be comparable to or longer than the diffusion time. The decoherence time reaches its minimal value for classical, completely decohered environment, suggesting that physical decoherence is slowed down as compared with diffusion by the quantum coherence of the environment.
Time scale in quasifission reactions
Back, B.B.; Paul, P.; Nestler, J. [and others
1995-08-01
The quasifission process arises from the hindrance of the complete fusion process when heavy-ion beams are used. The strong dissipation in the system tends to prevent fusion and lead the system towards reseparation into two final products of similar mass reminiscent of a fission process. This dissipation slows down the mass transfer and shape transformation and allows for the emission of high energy {gamma}-rays during the process, albeit with a low probability. Giant Dipole {gamma} rays emitted during this time have a characteristic spectral shape and may thus be discerned in the presence of a background of {gamma} rays emitted from the final fission-like fragments. Since the rate of GDR {gamma} emission is very well established, the strength of this component may therefore be used to measure the timescale of the quasifission process. In this experiment we studied the reaction between 368-MeV {sup 58}Ni and a {sup 165}Ho target, where deep inelastic scattering and quasifission processes are dominant. Coincidences between fission fragments (detected in four position-sensitive avalanche detectors) and high energy {gamma} rays (measured in a 10{close_quotes} x 10{close_quotes} actively shielded NaI detector) were registered. Beams were provided by the Stony Brook Superconducting Linac. The {gamma}-ray spectrum associated with deep inelastic scattering events is well reproduced by statistical cooling of projectile and target-like fragments with close to equal initial excitation energy sharing. The y spectrum associated with quasifission events is well described by statistical emission from the fission fragments alone, with only weak evidence for GDR emission from the mono-nucleus. A 1{sigma} limit of t{sub ss} < 11 x 10{sup -21} s is obtained for the mono-nucleus lifetime, which is consistent with the lifetime obtained from quasifission fragment angular distributions. A manuscript was accepted for publication.
Stochastic dynamic equations on general time scales
Martin Bohner
2013-02-01
Full Text Available In this article, we construct stochastic integral and stochastic differential equations on general time scales. We call these equations stochastic dynamic equations. We provide the existence and uniqueness theorem for solutions of stochastic dynamic equations. The crucial tool of our construction is a result about a connection between the time scales Lebesgue integral and the Lebesgue integral in the common sense.
Some integral inequalities on time scales
Adnan Tuna; Servet Kutukcu
2008-01-01
In this article, we study the reverse Holder type inequality and Holder in-equality in two dimensional case on time scales. We also obtain many integral inequalities by using H(o)lder inequalities on time scales which give Hardy's inequalities as spacial cases.
Kalman plus weights: a time scale algorithm
Greenhall, C. A.
2001-01-01
KPW is a time scale algorithm that combines Kalman filtering with the basic time scale equation (BTSE). A single Kalman filter that estimates all clocks simultaneously is used to generate the BTSE frequency estimates, while the BTSE weights are inversely proportional to the white FM variances of the clocks. Results from simulated clock ensembles are compared to previous simulation results from other algorithms.
Adolescent Time Attitude Scale: Adaptation into Turkish
Çelik, Eyüp; Sahranç, Ümit; Kaya, Mehmet; Turan, Mehmet Emin
2017-01-01
This research is aimed at examining the validity and reliability of the Turkish version of the Time Attitude Scale. Data was collected from 433 adolescents; 206 males and 227 females participated in the study. Confirmatory factor analysis performed to discover the structural validity of the scale. The internal consistency method was used for…
Hardy type inequalities on time scales
Agarwal, Ravi P; Saker, Samir H
2016-01-01
The book is devoted to dynamic inequalities of Hardy type and extensions and generalizations via convexity on a time scale T. In particular, the book contains the time scale versions of classical Hardy type inequalities, Hardy and Littlewood type inequalities, Hardy-Knopp type inequalities via convexity, Copson type inequalities, Copson-Beesack type inequalities, Liendeler type inequalities, Levinson type inequalities and Pachpatte type inequalities, Bennett type inequalities, Chan type inequalities, and Hardy type inequalities with two different weight functions. These dynamic inequalities contain the classical continuous and discrete inequalities as special cases when T = R and T = N and can be extended to different types of inequalities on different time scales such as T = hN, h > 0, T = qN for q > 1, etc.In this book the authors followed the history and development of these inequalities. Each section in self-contained and one can see the relationship between the time scale versions of the inequalities and...
The Second Noether Theorem on Time Scales
Malinowska, Agnieszka B.; Natália Martins
2013-01-01
We extend the second Noether theorem to variational problems on time scales. As corollaries we obtain the classical second Noether theorem, the second Noether theorem for the $h$ -calculus and the second Noether theorem for the $q$ -calculus.
Time invariant scaling in discrete fragmentation models
Giraud, B G; Giraud, B G; Peschanski, R
1994-01-01
Linear rate equations are used to describe the cascading decay of an initial heavy cluster into fragments. We consider moments of arbitrary orders of the mass multiplicity spectrum and derive scaling properties pertaining to their time evolution. We suggest that the mass weighted multiplicity is a suitable observable for the discovery of scaling. Numerical tests validate such properties, even for moderate values of the initial mass (nuclei, percolation clusters, jets of particles etc.). Finite size effects can be simply parametrized.
An evaluation of the hydrologic relevance of lateral flow in snow at hillslope and catchment scales
David Eiriksson; Michael Whitson; Charles H. Luce; Hans Peter Marshall; John Bradford; Shawn G. Benner; Thomas Black; Hank Hetrick; James P. McNamara
2013-01-01
Lateral downslope flow in snow during snowmelt and rain-on-snow (ROS) events is a well-known phenomenon, yet its relevance to water redistribution at hillslope and catchment scales is not well understood. We used dye tracers, geophysical methods, and hydrometric measurements to describe the snow properties that promote lateral flow, assess the relative velocities of...
Reneman, Michiel F.; Geertzen, Jan H. B.; Jorritsma, Wim; Knol-de Vries, Grietje; Dijkstra, Pieter U.
2012-01-01
To investigate relevant change on the Neck Pain and Disability Scale (NPAD) and Neck Disability Index (NDI) and which questionnaire is the most responsive in patients with non-specific chronic neck pain (CNP). Seventy-six patients with non-specific CNP in an outpatient tertiary rehabilitation settin
de Bruin, E.J.; van Kampen, R.K.A.; van Kooten, T.; Meijer, A.M.
2014-01-01
Objective: This study investigated reliability, validity, and clinical relevance of the Adolescent Sleep Hygiene Scale (ASHS) in Dutch adolescents. Methods: The Dutch translation of the ASHS was administered to 186 normal-sleeping adolescents and 112 adolescents with insomnia. Their sleep variables
de Bruin, E.J.; van Kampen, R.K.A.; van Kooten, T.; Meijer, A.M.
2014-01-01
Objective: This study investigated reliability, validity, and clinical relevance of the Adolescent Sleep Hygiene Scale (ASHS) in Dutch adolescents. Methods: The Dutch translation of the ASHS was administered to 186 normal-sleeping adolescents and 112 adolescents with insomnia. Their sleep variables
Multivariable dynamic calculus on time scales
Bohner, Martin
2016-01-01
This book offers the reader an overview of recent developments of multivariable dynamic calculus on time scales, taking readers beyond the traditional calculus texts. Covering topics from parameter-dependent integrals to partial differentiation on time scales, the book’s nine pedagogically oriented chapters provide a pathway to this active area of research that will appeal to students and researchers in mathematics and the physical sciences. The authors present a clear and well-organized treatment of the concept behind the mathematics and solution techniques, including many practical examples and exercises.
Transient time-domain resonances and the time scale for tunneling
García-Calderón, G; Garc\\'{\\i}a-Calder\\'on, Gast\\'on; Villavicencio, Jorge
2003-01-01
Transient {\\it time-domain resonances} found recently in time-dependent solutions to Schr\\"{o}dinger's equation are used to investigate the issue of the tunneling time in rectangular potential barriers. In general, a time frequency analysis shows that these transients have frequencies above the cutoff frequency associated with the barrier height, and hence correspond to non-tunneling processes. We find, however, a regime characterized by the barrier opacity, where the peak maximum $t_{max}$ of the {\\it time-domain resonance} corresponds to under-the-barrier tunneling. We argue that $t_{max}$ represents the relevant tunneling time scale through the classically forbidden region.
Marine Climate Services ‐ Forecasting the state of the ocean at end‐user relevant time‐scale
Payne, Mark
Recent advances in oceanographic modelling mean that today we can forecast the state of the ocean with meaningful skill up to a decade in advance. Such forecasts are potentially of great value to society, as they span the gap between the short (days-to-weeks) time scales of weather forecasts and ......) in the North Atlantic. Further opportunities for forecasting variables, both globally and that are of direct relevance to Danish end-users will also be presented.......Recent advances in oceanographic modelling mean that today we can forecast the state of the ocean with meaningful skill up to a decade in advance. Such forecasts are potentially of great value to society, as they span the gap between the short (days-to-weeks) time scales of weather forecasts...... and the long (century) time-scales of climate projections: importantly, these are the time scales where most users make important decisions. However, a translation step is required to convert the outputs from these models, which are typically physical variables, into variables that are directly relevant to end...
The scaling law of climate change and its relevance to assessing (palaeo)biological responses
Kiessling, Wolfgang; Eichenseer, Kilian
2014-05-01
interglacials, are not monotonic, but punctuated by short-term cooling intervals. The fossil record tells us that biodiversity responded dramatically to ancient intervals of climate warming. We can now see that the apparently slower rates of change in some mass extinctions (Permian-Triassic, Triassic-Jurassic) were greater than today when the scaling law is considered. This reassures us that studying deep time patterns of organismic response to climate change is a worthwhile endeavor that is relevant for predicting the future. References Burrows, M. T., Schoeman, D. S., Buckley, L. B., Moore, P., Poloczanska, E. S., Brander, K. M., Brown, C., Bruno, J. F., Duarte, C. M., Halpern, B. S., Holding, J., Kappel, C. V., Kiessling, W., O'Connor, M. I., Pandolfi, J. M., Parmesan, C., Schwing, F. B., Sydeman, W. J., and Richardson, A. J.: The pace of shifting climate in marine and terrestrial ecosystems, Science, 334, 652-655, 2011. Gingerich, P. D.: Quantification and comparison of evolutionary rates, American Journal of Science, 293A, 453-478, 1993. Sadler, P. M.: Sediment accumulation rates and the completeness of stratigraphic sections, Journal of Geology, 89, 569-584, 1981. Sun, Y., Joachimski, M. M., Wignall, P. B., Yan, C., Chen, Y., Jiang, H., Wang, L., and Lai, X.: Lethally hot temperatures during the Early Triassic greenhouse, Science, 338, 366-370, 2012.
Time Relevance of Convective Weather Forecast for Air Traffic Automation
Chan, William N.
2006-01-01
The Federal Aviation Administration (FAA) is handling nearly 120,000 flights a day through its Air Traffic Management (ATM) system and air traffic congestion is expected to increse substantially over the next 20 years. Weather-induced impacts to throughput and efficiency are the leading cause of flight delays accounting for 70% of all delays with convective weather accounting for 60% of all weather related delays. To support the Next Generation Air Traffic System goal of operating at 3X current capacity in the NAS, ATC decision support tools are being developed to create advisories to assist controllers in all weather constraints. Initial development of these decision support tools did not integrate information regarding weather constraints such as thunderstorms and relied on an additional system to provide that information. Future Decision Support Tools should move towards an integrated system where weather constraints are factored into the advisory of a Decision Support Tool (DST). Several groups such at NASA-Ames, Lincoln Laboratories, and MITRE are integrating convective weather data with DSTs. A survey of current convective weather forecast and observation data show they span a wide range of temporal and spatial resolutions. Short range convective observations can be obtained every 5 mins with longer range forecasts out to several days updated every 6 hrs. Today, the short range forecasts of less than 2 hours have a temporal resolution of 5 mins. Beyond 2 hours, forecasts have much lower temporal. resolution of typically 1 hour. Spatial resolutions vary from 1km for short range to 40km for longer range forecasts. Improving the accuracy of long range convective forecasts is a major challenge. A report published by the National Research Council states improvements for convective forecasts for the 2 to 6 hour time frame will only be achieved for a limited set of convective phenomena in the next 5 to 10 years. Improved longer range forecasts will be probabilistic
Structure of Student Time Management Scale (STMS)
Balamurugan, M.
2013-01-01
With the aim of constructing a Student Time Management Scale (STMS), the initial version was administered and data were collected from 523 standard eleventh students. (Mean age = 15.64). The data obtained were subjected to Reliability and Factor analysis using PASW Statistical software version 18. From 42 items 14 were dropped, resulting in the…
Some Nonlinear Dynamic Inequalities on Time Scales
Wei Nian Li; Weihong Sheng
2007-11-01
The aim of this paper is to investigate some nonlinear dynamic inequalities on time scales, which provide explicit bounds on unknown functions. The inequalities given here unify and extend some inequalities in (B G Pachpatte, On some new inequalities related to a certain inequality arising in the theory of differential equation, J. Math. Anal. Appl. 251 (2000) 736--751).
The Second Noether Theorem on Time Scales
Agnieszka B. Malinowska
2013-01-01
Full Text Available We extend the second Noether theorem to variational problems on time scales. As corollaries we obtain the classical second Noether theorem, the second Noether theorem for the h-calculus and the second Noether theorem for the q-calculus.
The second Noether theorem on time scale
Malinowska, Agnieszka B.; Martins, Natália
2014-01-01
We extend the second Noether theorem to variational problems on time scales. Our result provides as corollaries the classical second Noether theorem, the second Noether theorem for the $h$-calculus and the second Noether theorem for the $q$-calculus.
Some Nonlinear Integral Inequalities on Time Scales
Li Wei Nian
2007-01-01
Full Text Available The purpose of this paper is to investigate some nonlinear integral inequalities on time scales. Our results unify and extend some continuous inequalities and their corresponding discrete analogues. The theoretical results are illustrated by a simple example at the end of this paper.
Scale Invariance in Rain Time Series
Deluca, A.; Corral, A.
2009-09-01
In the last few years there have been pieces of evidence that rain events can be considered analogous to other nonequilibrium relaxation processes in Nature such as earthquakes, solar flares and avalanches. In this work we compare the probability densities of rain event size, duration, and recurrence times (i.e., drought periods) between one Mediterranean site and different sites worldwide. We test the existence of scale invariance in these distributions and the possibility of a universal scaling exponent, despite the different climatic characteristics of the different places.
Controllability of multiplex, multi-time-scale networks
Pósfai, Márton; Gao, Jianxi; Cornelius, Sean P.; Barabási, Albert-László; D'Souza, Raissa M.
2016-09-01
The paradigm of layered networks is used to describe many real-world systems, from biological networks to social organizations and transportation systems. While recently there has been much progress in understanding the general properties of multilayer networks, our understanding of how to control such systems remains limited. One fundamental aspect that makes this endeavor challenging is that each layer can operate at a different time scale; thus, we cannot directly apply standard ideas from structural control theory of individual networks. Here we address the problem of controlling multilayer and multi-time-scale networks focusing on two-layer multiplex networks with one-to-one interlayer coupling. We investigate the practically relevant case when the control signal is applied to the nodes of one layer. We develop a theory based on disjoint path covers to determine the minimum number of inputs (Ni) necessary for full control. We show that if both layers operate on the same time scale, then the network structure of both layers equally affect controllability. In the presence of time-scale separation, controllability is enhanced if the controller interacts with the faster layer: Ni decreases as the time-scale difference increases up to a critical time-scale difference, above which Ni remains constant and is completely determined by the faster layer. We show that the critical time-scale difference is large if layer I is easy and layer II is hard to control in isolation. In contrast, control becomes increasingly difficult if the controller interacts with the layer operating on the slower time scale and increasing time-scale separation leads to increased Ni, again up to a critical value, above which Ni still depends on the structure of both layers. This critical value is largely determined by the longest path in the faster layer that does not involve cycles. By identifying the underlying mechanisms that connect time-scale difference and controllability for a simplified
Significance of time scale differences in psychophysics.
Klonowski, W
2009-02-01
We present modeling of both rational processes (thoughts) and emotional processes (feelings) on a two-dimensional lattice and on extremely simplified two-dimensional phase space of the brain. Our purpose is to analyze influence of differences in time-scales of various types of processes. In particular, we show that no 'central executive structure' between consciousness and unconsciousness, the existence of which was suggested by psychologists, is not needed.
Scaling of light and dark time intervals.
Marinova, J
1978-01-01
Scaling of light and dark time intervals of 0.1 to 1.1 s is performed by the mehtod of magnitude estimation with respect to a given standard. The standards differ in duration and type (light and dark). The light intervals are subjectively estimated as longer than the dark ones. The relation between the mean interval estimations and their magnitude is linear for both light and dark intervals.
Special Issue on Time Scale Algorithms
2008-01-01
unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 IOP PUBLISHING METROLOGIA Metrologia 45 (2008) doi:10.1088/0026-1394/45/6/E01...special issue of Metrologia presents selected papers from the Fifth International Time Scale Algorithm Symposium (VITSAS), including some of the...Paris at the BIPM in 2002 (see Metrologia 40 (3), 2003) • 5th Symposium: in San Fernando, Spain at the ROA in 2008. The early symposia were concerned
Helmuth, Brian; Broitman, Bernardo R; Yamane, Lauren; Gilman, Sarah E; Mach, Katharine; Mislan, K A S; Denny, Mark W
2010-03-15
Predicting when, where and with what magnitude climate change is likely to affect the fitness, abundance and distribution of organisms and the functioning of ecosystems has emerged as a high priority for scientists and resource managers. However, even in cases where we have detailed knowledge of current species' range boundaries, we often do not understand what, if any, aspects of weather and climate act to set these limits. This shortcoming significantly curtails our capacity to predict potential future range shifts in response to climate change, especially since the factors that set range boundaries under those novel conditions may be different from those that set limits today. We quantitatively examine a nine-year time series of temperature records relevant to the body temperatures of intertidal mussels as measured using biomimetic sensors. Specifically, we explore how a 'climatology' of body temperatures, as opposed to long-term records of habitat-level parameters such as air and water temperatures, can be used to extrapolate meaningful spatial and temporal patterns of physiological stress. Using different metrics that correspond to various aspects of physiological stress (seasonal means, cumulative temperature and the return time of extremes) we show that these potential environmental stressors do not always occur in synchrony with one another. Our analysis also shows that patterns of animal temperature are not well correlated with simple, commonly used metrics such as air temperature. Detailed physiological studies can provide guidance to predicting the effects of global climate change on natural ecosystems but only if we concomitantly record, archive and model environmental signals at appropriate scales.
Liquidity crises on different time scales
Corradi, Francesco; Zaccaria, Andrea; Pietronero, Luciano
2015-12-01
We present an empirical analysis of the microstructure of financial markets and, in particular, of the static and dynamic properties of liquidity. We find that on relatively large time scales (15 min) large price fluctuations are connected to the failure of the subtle mechanism of compensation between the flows of market and limit orders: in other words, the missed revelation of the latent order book breaks the dynamical equilibrium between the flows, triggering the large price jumps. On smaller time scales (30 s), instead, the static depletion of the limit order book is an indicator of an intrinsic fragility of the system, which is related to a strongly nonlinear enhancement of the response. In order to quantify this phenomenon we introduce a measure of the liquidity imbalance present in the book and we show that it is correlated to both the sign and the magnitude of the next price movement. These findings provide a quantitative definition of the effective liquidity, which proves to be strongly dependent on the considered time scales.
Freunberger, S. A.
2007-07-01
This dissertation is concerned with the development, experimental diagnostics and mathematical modelling and simulation of polymer electrolyte fuel cells (PEFC). The central themes throughout this thesis are the closely interlinked phenomena of mass and charge transfer. In the face of developing a PEFC system for vehicle propulsion these phenomena are scrutinized on a broad range of relevant scales. Starting from the material related level of the membrane and the gas diffusion layer (GDL) we turn to length scales, where structural features of the cell additionally come into play. These are the scale of flow channels and ribs, the single cell and the cell stack followed by the cell, stack, and system development for an automotive power train. In Chapter 3 selected fundamental material models and properties, respectively, are explored that are crucial for the mathematical modelling and simulation of PEFC, as needed in some succeeding parts of this work. First, established mathematical models for mass and charge transfer in the membrane are compared within the framework of the membrane electrode assembly (MEA), which represents the electrochemical unit. Second, reliable values for effective diffusivities in the GDLs which are vital for the simulation of gaseous mass transport are measured. Therefore, a method is developed that allows measuring this quantity both as a function of compression and direction as this is a prerequisite of sophisticated more-dimensional numerical PEFC-models. Besides the cross section of the catalyst layer (CL) mass transfer under channels and ribs is considered as a major source of losses in particular under high load operation. As up to now there have been solely non-validated theoretical investigations, in Chapter 4 an experimental method is developed that is for the first time capable of resolving the current density distribution on the this scale. For this, the electron conductors in the cell are considered as 2-dimensional shunt
Multidimensional scaling of musical time estimations.
Cocenas-Silva, Raquel; Bueno, José Lino Oliveira; Molin, Paul; Bigand, Emmanuel
2011-06-01
The aim of this study was to identify the psycho-musical factors that govern time evaluation in Western music from baroque, classic, romantic, and modern repertoires. The excerpts were previously found to represent variability in musical properties and to induce four main categories of emotions. 48 participants (musicians and nonmusicians) freely listened to 16 musical excerpts (lasting 20 sec. each) and grouped those that seemed to have the same duration. Then, participants associated each group of excerpts to one of a set of sine wave tones varying in duration from 16 to 24 sec. Multidimensional scaling analysis generated a two-dimensional solution for these time judgments. Musical excerpts with high arousal produced an overestimation of time, and affective valence had little influence on time perception. The duration was also overestimated when tempo and loudness were higher, and to a lesser extent, timbre density. In contrast, musical tension had little influence.
uncertain dynamic systems on time scales
V. Lakshmikantham
1995-01-01
Full Text Available A basic feedback control problem is that of obtaining some desired stability property from a system which contains uncertainties due to unknown inputs into the system. Despite such imperfect knowledge in the selected mathematical model, we often seek to devise controllers that will steer the system in a certain required fashion. Various classes of controllers whose design is based on the method of Lyapunov are known for both discrete [4], [10], [15], and continuous [3–9], [11] models described by difference and differential equations, respectively. Recently, a theory for what is known as dynamic systems on time scales has been built which incorporates both continuous and discrete times, namely, time as an arbitrary closed sets of reals, and allows us to handle both systems simultaneously [1], [2], [12], [13]. This theory permits one to get some insight into and better understanding of the subtle differences between discrete and continuous systems. We shall, in this paper, utilize the framework of the theory of dynamic systems on time scales to investigate the stability properties of conditionally invariant sets which are then applied to discuss controlled systems with uncertain elements. For the notion of conditionally invariant set and its stability properties, see [14]. Our results offer a new approach to the problem in question.
Babcock, E.
2015-12-01
The best environmental education equips people with the know-how and drive to create healthy communities and a healthy planet. While there are many wonderful organizations providing environmental learning, ensuring quality, cultural relevance and equity of access remains an elusive goal--especially if environmental education organizations work in isolation. Organizations across 12 counties in the Bay Area have come together to create a different model. They have founded ChangeScale, a regional collaborative dedicated to providing high quality environmental education to hundreds of thousands of youth---by working together. ChangeScale's work involves setting up school district-level partnerships, providing technical assistance to local environmental education networks, and training environmental educators across the region. In this talk, the presenter, who is a founding member and steering committee chair for ChangeScale, will outline the challenges of working at a regional scale with dozens of organizations. She will share the processes ChangeScale has used to develop a business plan and build membership. She will conclude by sharing the short term and long term potential impacts of working collectively for environmental literacy in the Bay Area.
Freunberger, S. A.
2007-07-01
This dissertation is concerned with the development, experimental diagnostics and mathematical modelling and simulation of polymer electrolyte fuel cells (PEFC). The central themes throughout this thesis are the closely interlinked phenomena of mass and charge transfer. In the face of developing a PEFC system for vehicle propulsion these phenomena are scrutinized on a broad range of relevant scales. Starting from the material related level of the membrane and the gas diffusion layer (GDL) we turn to length scales, where structural features of the cell additionally come into play. These are the scale of flow channels and ribs, the single cell and the cell stack followed by the cell, stack, and system development for an automotive power train. In Chapter 3 selected fundamental material models and properties, respectively, are explored that are crucial for the mathematical modelling and simulation of PEFC, as needed in some succeeding parts of this work. First, established mathematical models for mass and charge transfer in the membrane are compared within the framework of the membrane electrode assembly (MEA), which represents the electrochemical unit. Second, reliable values for effective diffusivities in the GDLs which are vital for the simulation of gaseous mass transport are measured. Therefore, a method is developed that allows measuring this quantity both as a function of compression and direction as this is a prerequisite of sophisticated more-dimensional numerical PEFC-models. Besides the cross section of the catalyst layer (CL) mass transfer under channels and ribs is considered as a major source of losses in particular under high load operation. As up to now there have been solely non-validated theoretical investigations, in Chapter 4 an experimental method is developed that is for the first time capable of resolving the current density distribution on the this scale. For this, the electron conductors in the cell are considered as 2-dimensional shunt
Time-Scale Invariant Audio Data Embedding
Mansour Mohamed F
2003-01-01
Full Text Available We propose a novel algorithm for high-quality data embedding in audio. The algorithm is based on changing the relative length of the middle segment between two successive maximum and minimum peaks to embed data. Spline interpolation is used to change the lengths. To ensure smooth monotonic behavior between peaks, a hybrid orthogonal and nonorthogonal wavelet decomposition is used prior to data embedding. The possible data embedding rates are between 20 and 30 bps. However, for practical purposes, we use repetition codes, and the effective embedding data rate is around 5 bps. The algorithm is invariant after time-scale modification, time shift, and time cropping. It gives high-quality output and is robust to mp3 compression.
Groundwater in the Earth's critical zone: Relevance to large-scale patterns and processes
Fan, Ying
2015-05-01
Although we have an intuitive understanding of the behavior and functions of groundwater in the Earth's critical zone at the scales of a column (atmosphere-plant-soil-bedrock), along a toposequence (ridge to valley), and across a small catchment (up to third-order streams), this paper attempts to assess the relevance of groundwater to understanding large-scale patterns and processes such as represented in global climate and Earth system models. Through observation syntheses and conceptual models, evidence are presented that groundwater influence is globally prevalent, it forms an environmental gradient not fully captured by the climate, and it can profoundly shape critical zone evolution at continental to global scales. Four examples are used to illustrate these ideas: (1) groundwater as a water source for plants in rainless periods, (2) water table depth as a driver of plant rooting depth, (3) the accessibility of groundwater as an ecological niche separator, and (4) groundwater as the lower boundary of land drainage and a global driver of wetlands. The implications to understanding past and future global environmental change are briefly discussed, as well as critical discipline, scale, and data gaps that must be bridged in order for us to translate what we learn in the field at column, hillslope and catchment scales, to what we must predict at regional, continental, and global scales.
Discounting in Games across Time Scales
Krishnendu Chatterjee
2010-06-01
Full Text Available We introduce two-level discounted games played by two players on a perfect-information stochastic game graph. The upper level game is a discounted game and the lower level game is an undiscounted reachability game. Two-level games model hierarchical and sequential decision making under uncertainty across different time scales. We show the existence of pure memoryless optimal strategies for both players and an ordered field property for such games. We show that if there is only one player (Markov decision processes, then the values can be computed in polynomial time. It follows that whether the value of a player is equal to a given rational constant in two-level discounted games can be decided in NP intersected coNP. We also give an alternate strategy improvement algorithm to compute the value.
Discounting in Games across Time Scales
Chatterjee, Krishnendu; 10.4204/EPTCS.25.6
2010-01-01
We introduce two-level discounted games played by two players on a perfect-information stochastic game graph. The upper level game is a discounted game and the lower level game is an undiscounted reachability game. Two-level games model hierarchical and sequential decision making under uncertainty across different time scales. We show the existence of pure memoryless optimal strategies for both players and an ordered field property for such games. We show that if there is only one player (Markov decision processes), then the values can be computed in polynomial time. It follows that whether the value of a player is equal to a given rational constant in two-level discounted games can be decided in NP intersected coNP. We also give an alternate strategy improvement algorithm to compute the value.
Extension of gyrokinetics to transport time scales
Parra, Felix I
2013-01-01
Gyrokinetic simulations have greatly improved our theoretical understanding of turbulent transport in fusion devices. Most gyrokinetic models in use are delta-f simulations in which the slowly varying radial profiles of density and temperature are assumed to be constant for turbulence saturation times, and only the turbulent electromagnetic fluctuations are calculated. New massive simulations are being built to self-consistently determine the radial profiles of density and temperature. However, these new codes have failed to realize that modern gyrokinetic formulations, composed of a gyrokinetic Fokker-Planck equation and a gyrokinetic quasineutrality equation, are only valid for delta-f simulations that do not reach the longer transport time scales necessary to evolve radial profiles. In tokamaks, due to axisymmetry, the evolution of the axisymmetric radial electric field is a challenging problem requiring substantial modifications to gyrokinetic treatments. In this thesis, I study the effect of turbulence o...
Spur in pico-second time scales
Gopinathan, C.; Girija, G. (Bhabha Atomic Research Centre, Bombay (India). Chemistry Div.)
1983-01-01
The spur diffusion model of aqueous radiation chemistry, proposed in 1953, had run into difficulties with the development of pico-second pulse radiolysis in the late 1960s and early seventies. Using the same values for spur parameters, it was impossible to get good agreement with e/sup -/sub(aq) and OH decay in pico and nano second time scales as well as the steady state molecular product yield measurements. This inconsistency was removed by us by assuming that for a given number of dissociations, a number of radii values for the spur are possible, these radii values being related in a gaussian manner. This new approach proved highly successful in getting agreement between the predictions of the spur diffusion model and the pulse radiolysis results as well as the steady state molecular product yield measurements. Our computations have been extended to cover the entire range of spurs from a single dissociation spur to a thirty dissociation spur. Here again agreement with experimental results is good. This approach also gives interesting insights about the spur formation processes in pico and possibly femto second time scales. We have calculated rate constants for the reactions involving the 'precursor' of the hydrated electron with a number of ions.
Scale relativity and fractal space-time: theory and applications
Nottale, Laurent
2008-01-01
In the first part of this contribution, we review the development of the theory of scale relativity and its geometric framework constructed in terms of a fractal and nondifferentiable continuous space-time. This theory leads (i) to a generalization of possible physically relevant fractal laws, written as partial differential equation acting in the space of scales, and (ii) to a new geometric foundation of quantum mechanics and gauge field theories and their possible generalisations. In the second part, we discuss some examples of application of the theory to various sciences, in particular in cases when the theoretical predictions have been validated by new or updated observational and experimental data. This includes predictions in physics and cosmology (value of the QCD coupling and of the cosmological constant), to astrophysics and gravitational structure formation (distances of extrasolar planets to their stars, of Kuiper belt objects, value of solar and solar-like star cycles), to sciences of life (log-p...
Scale-up considerations relevant to experimental studies of nuclear waste-package behavior
Coles, D.G.; Peters, R.D.
1986-04-01
Results from a study that investigated whether testing large-scale nuclear waste-package assemblages was technically warranted are reported. It was recognized that the majority of the investigations for predicting waste-package performance to date have relied primarily on laboratory-scale experimentation. However, methods for the successful extrapolation of the results from such experiments, both geometrically and over time, to actual repository conditions have not been well defined. Because a well-developed scaling technology exists in the chemical-engineering discipline, it was presupposed that much of this technology could be applicable to the prediction of waste-package performance. A review of existing literature documented numerous examples where a consideration of scaling technology was important. It was concluded that much of the existing scale-up technology is applicable to the prediction of waste-package performance for both size and time extrapolations and that conducting scale-up studies may be technically merited. However, the applicability for investigating the complex chemical interactions needs further development. It was recognized that the complexity of the system, and the long time periods involved, renders a completely theoretical approach to performance prediction almost hopeless. However, a theoretical and experimental study was defined for investigating heat and fluid flow. It was concluded that conducting scale-up modeling and experimentation for waste-package performance predictions is possible using existing technology. A sequential series of scaling studies, both theoretical and experimental, will be required to formulate size and time extrapolations of waste-package performance.
EDITORIAL: Special issue on time scale algorithms
Matsakis, Demetrios; Tavella, Patrizia
2008-12-01
This special issue of Metrologia presents selected papers from the Fifth International Time Scale Algorithm Symposium (VITSAS), including some of the tutorials presented on the first day. The symposium was attended by 76 persons, from every continent except Antarctica, by students as well as senior scientists, and hosted by the Real Instituto y Observatorio de la Armada (ROA) in San Fernando, Spain, whose staff further enhanced their nation's high reputation for hospitality. Although a timescale can be simply defined as a weighted average of clocks, whose purpose is to measure time better than any individual clock, timescale theory has long been and continues to be a vibrant field of research that has both followed and helped to create advances in the art of timekeeping. There is no perfect timescale algorithm, because every one embodies a compromise involving user needs. Some users wish to generate a constant frequency, perhaps not necessarily one that is well-defined with respect to the definition of a second. Other users might want a clock which is as close to UTC or a particular reference clock as possible, or perhaps wish to minimize the maximum variation from that standard. In contrast to the steered timescales that would be required by those users, other users may need free-running timescales, which are independent of external information. While no algorithm can meet all these needs, every algorithm can benefit from some form of tuning. The optimal tuning, and even the optimal algorithm, can depend on the noise characteristics of the frequency standards, or of their comparison systems, the most precise and accurate of which are currently Two Way Satellite Time and Frequency Transfer (TWSTFT) and GPS carrier phase time transfer. The interest in time scale algorithms and its associated statistical methodology began around 40 years ago when the Allan variance appeared and when the metrological institutions started realizing ensemble atomic time using more than
Neby, Simon; Sobolowski, Stefan
2017-04-01
How can users and stakeholders be actively involved with providing input to and using output from local-scale climate projections? How can the scientific community better understand the needs of local actors? And how should communication and cooperation efforts be organized? These are critical questions we aim to answer in a climate services project funded by the Norwegian Research Council (R3: Relevant, Reliable and Robust local-scale climate projections for Norway). The project takes into consideration not only the scientific issues in establishing useful local-scale climate projections, but also addresses the "usability gap" between climate information and decision-making. The lack of effective communication between scientists and user communities often result in outputs and products that are not matched with decision-relevant climate information. In the R3 project, the scientific participants actively engage with a range of users that have quite different information needs: municipalities, infrastructure developers, agriculture, energy producers, insurance companies, and more. In this particular presentation, we present our experiences concerning three specific issues that relate to the stakeholder-science interface: 1) Preferences are not clear-cut and pre-defined. In practice, this means that stakeholders often do not have precise information about their needs, nor precise information about how, where and whether their needs can be voiced. Similarly, science communities tend to presuppose that stakeholders are interested and have well-articulated needs, which is hardly the case. Collectively, that means that there is a need for an approach that guides the articulation and prioritization of preferences in a manner that integrates both scientific and stakeholder perspectives and takes the integrity of both perspectives seriously. 2) Technologies are unclear. Although information may be produced and used, past experiences, trial and error processes and pragmatic
Time Horizon and Social Scale in Communication
Krantz, D. H.
2010-12-01
In 2009 our center (CRED) published a first version of The Psychology of Climate Change Communication. In it, we attempted to summarize facts and concepts from psychological research that could help guide communication. While this work focused on climate change, most of the ideas are at least partly applicable for communication about a variety of natural hazards. Of the many examples in this guide, I mention three. Single-action bias is the human tendency to stop considering further actions that might be needed to deal with a given hazard, once a single action has been taken. Another example is the importance of group affiliation in motivating voluntary contributions to joint action. A third concerns the finding that group participation enhances understanding of probabilistic concepts and promotes action in the face of uncertainty. One current research direction, which goes beyond those included in the above publication, focuses on how time horizons arise in the thinking of individuals and groups, and how these time horizons might influence hazard preparedness. On the one hand, individuals sometimes appear impatient, organizations look for immediate results, and officials fail to look beyond the next election cycle. Yet under some laboratory conditions and in some subcultures, a longer time horizon is adopted. We are interested in how time horizon is influenced by group identity and by the very architecture of planning and decision making. Institutional changes, involving long-term contractual relationships among communities, developers, insurers, and governments, could greatly increase resilience in the face of natural hazards. Communication about hazards, in the context of such long-term contractual relationships might look very different from communication that is first initiated by immediate threat. Another new direction concerns the social scale of institutions and of communication about hazards. Traditionally, insurance contracts share risk among a large
Scaling Fire Regimes in Space and Time.
Falk, D. A.
2004-12-01
Spatial and temporal variability are important properties of the forest fire regimes of coniferous forests of southwestern North America. We use a variety of analytical techniques to examine scaling in a surface fire regime in the Jemez Mountains of northern New Mexico, USA, based on an original data set collected from Monument Canyon Research Natural Area (MCN). Spatio-temporal scale dependence in the fire regime can be analyzed quantitatively using statistical descriptors of the fire regime, such as fire frequency and mean fire interval. We describe a theory of the event-area (EA) relationship, an extension of the species-area relationship for events distributed in space and time; the interval-area (IA) relationship, is a related form for fire intervals. We use the EA and IA to demonstrate scale dependence in the MCN fire regime. The slope and intercept of these functions are influenced by fire size, frequency, and spatial distribution, and thus are potentially useful metrics of spatio-temporal synchrony of events in the paleofire record. Second, we outline a theory of fire interval probability, working from first principles in fire ecology and statistics. Fires are conditional events resulting from the interaction of multiple contingent factors that must be satisfied for an event to occur. Outcomes of this kind represent a multiplicative process for which a lognormal model is the limiting distribution. We examine the application of this framework to two probability models, the Weibull and lognormal distributions, which can be used to characterize the distribution of fire intervals over time. Lastly, we present a general model for the collector's curve, with application to the theory and effects of sample size in fire history. Sources of uncertainty in fire history can be partitioned into an error typology; analytical methods used in fire history (particularly the formation of composite fire records) are designed to minimize certain types of error in inference
Valentin Jossen
2016-01-01
Full Text Available The potential of human mesenchymal stem cells (hMSCs for allogeneic cell therapies has created a large amount of interest. However, this presupposes the availability of efficient scale-up procedures. Promising results have been reported for stirred bioreactors that operate with microcarriers. Recent publications focusing on microcarrier-based stirred bioreactors have demonstrated the successful use of Computational Fluid Dynamics (CFD and suspension criteria (NS1u, NS1 for rapidly scaling up hMSC expansions from mL- to pilot scale. Nevertheless, one obstacle may be the formation of large microcarrier-cell-aggregates, which may result in mass transfer limitations and inhomogeneous distributions of stem cells in the culture broth. The dependence of microcarrier-cell-aggregate formation on impeller speed and shear stress levels was investigated for human adipose derived stromal/stem cells (hASCs at the spinner scale by recording the Sauter mean diameter (d32 versus time. Cultivation at the suspension criteria provided d32 values between 0.2 and 0.7 mm, the highest cell densities (1.25 × 106 cells mL−1 hASCs, and the highest expansion factors (117.0 ± 4.7 on day 7, while maintaining the expression of specific surface markers. Furthermore, suitability of the suspension criterion NS1u was investigated for scaling up microcarrier-based processes in wave-mixed bioreactors for the first time.
Tuning Piezo ion channels to detect molecular-scale movements relevant for fine touch.
Poole, Kate; Herget, Regina; Lapatsina, Liudmila; Ngo, Ha-Duong; Lewin, Gary R
2014-03-24
In sensory neurons, mechanotransduction is sensitive, fast and requires mechanosensitive ion channels. Here we develop a new method to directly monitor mechanotransduction at defined regions of the cell-substrate interface. We show that molecular-scale (~13 nm) displacements are sufficient to gate mechanosensitive currents in mouse touch receptors. Using neurons from knockout mice, we show that displacement thresholds increase by one order of magnitude in the absence of stomatin-like protein 3 (STOML3). Piezo1 is the founding member of a class of mammalian stretch-activated ion channels, and we show that STOML3, but not other stomatin-domain proteins, brings the activation threshold for Piezo1 and Piezo2 currents down to ~10 nm. Structure-function experiments localize the Piezo modulatory activity of STOML3 to the stomatin domain, and higher-order scaffolds are a prerequisite for function. STOML3 is the first potent modulator of Piezo channels that tunes the sensitivity of mechanically gated channels to detect molecular-scale stimuli relevant for fine touch.
Elizabeth Margaret Stovold
2017-06-01
Full Text Available A Review of: Hanneke, R., & O’Brien, K. K. (2016. Comparison of three web-scale discovery services for health sciences research. Journal of the Medical Library Association, 104(2, 109-117. http://dx.doi.org/10.3163/1536-5050.104.2.004 Abstract Objective – To compare the results of health sciences search queries in three web-scale discovery (WSD services for relevance, duplicate detection, and retrieval of MEDLINE content. Design – Comparative evaluation and bibliometric study. Setting – Six university libraries in the United States of America. Subjects – Three commercial WSD services: Primo, Summon, and EBSCO Discovery Service (EDS. Methods – The authors collected data at six universities, including their own. They tested each of the three WSDs at two data collection sites. However, since one of the sites was using a legacy version of Summon that was due to be upgraded, data collected for Summon at this site were considered obsolete and excluded from the analysis. The authors generated three questions for each of six major health disciplines, then designed simple keyword searches to mimic typical student search behaviours. They captured the first 20 results from each query run at each test site, to represent the first “page” of results, giving a total of 2,086 total search results. These were independently assessed for relevance to the topic. Authors resolved disagreements by discussion, and calculated a kappa inter-observer score. They retained duplicate records within the results so that the duplicate detection by the WSDs could be compared. They assessed MEDLINE coverage by the WSDs in several ways. Using precise strategies to generate a relevant set of articles, they conducted one search from each of the six disciplines in PubMed so that they could compare retrieval of MEDLINE content. These results were cross-checked against the first 20 results from the corresponding query in the WSDs. To aid investigation of overall
Validation of the Spanish-language version of the Relevant Outcome Scale for Alzheimer's Disease.
Carnero Pardo, C; López Alcalde, S; Espinosa García, M; Sánchez Magro, I
2017-09-01
The Relevant Outcome Scale for Alzheimer's Disease (ROSA) is a useful tool for evaluating and monitoring dementia patients. This study aims to evaluate the validity and reliability of the Spanish version of ROSA. Spanish multicentre study involving 39 researchers and including 237 patients with Alzheimer disease (78 mild, 79 moderate, and 80 severe). The patients were tested with the following: Mini-Mental State Examination (MMSE), Fototest, Neuropsychiatric Inventory (NPI), Blessed dementia scale, and a Spanish-language version of ROSA. A subsample of 40 subjects was retested in the 14 days following the initial evaluation. The construct validity was evaluated with the Spearman correlation coefficient (r), internal consistency with Cronbach's alpha (alpha), and test-retest reliability with the intraclass correlation coefficient (ICC). ROSA requires 13.8±7.4minutes to administer and its results show a significant association with the clinical stage of AD (mild, 116.7±23.1; moderate, 92.9±19.8; and severe, 64.3±22.6), and with results on the MMSE (r=0.68), Fototest (r=0.63), NPI (r=0.53), and Blessed dementia scale (r=-0.80). ROSA shows high internal consistency (alpha=0.90) and excellent test-retest reliability (ICC0.97). The Spanish version of ROSA is a brief, valid, and reliable tool permitting overall evaluation of patients with dementia. Copyright © 2016 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.
Detection of crossover time scales in multifractal detrended fluctuation analysis
Ge, Erjia; Leung, Yee
2013-04-01
Fractal is employed in this paper as a scale-based method for the identification of the scaling behavior of time series. Many spatial and temporal processes exhibiting complex multi(mono)-scaling behaviors are fractals. One of the important concepts in fractals is crossover time scale(s) that separates distinct regimes having different fractal scaling behaviors. A common method is multifractal detrended fluctuation analysis (MF-DFA). The detection of crossover time scale(s) is, however, relatively subjective since it has been made without rigorous statistical procedures and has generally been determined by eye balling or subjective observation. Crossover time scales such determined may be spurious and problematic. It may not reflect the genuine underlying scaling behavior of a time series. The purpose of this paper is to propose a statistical procedure to model complex fractal scaling behaviors and reliably identify the crossover time scales under MF-DFA. The scaling-identification regression model, grounded on a solid statistical foundation, is first proposed to describe multi-scaling behaviors of fractals. Through the regression analysis and statistical inference, we can (1) identify the crossover time scales that cannot be detected by eye-balling observation, (2) determine the number and locations of the genuine crossover time scales, (3) give confidence intervals for the crossover time scales, and (4) establish the statistically significant regression model depicting the underlying scaling behavior of a time series. To substantive our argument, the regression model is applied to analyze the multi-scaling behaviors of avian-influenza outbreaks, water consumption, daily mean temperature, and rainfall of Hong Kong. Through the proposed model, we can have a deeper understanding of fractals in general and a statistical approach to identify multi-scaling behavior under MF-DFA in particular.
Noether theorem for Birkhoffian systems on time scales
Song, Chuan-Jing; Zhang, Yi
2015-10-01
Birkhoff equations on time scales and Noether theorem for Birkhoffian system on time scales are studied. First, some necessary knowledge of calculus on time scales are reviewed. Second, Birkhoff equations on time scales are obtained. Third, the conditions for invariance of Pfaff action and conserved quantities are presented under the special infinitesimal transformations and general infinitesimal transformations, respectively. Fourth, some special cases are given. And finally, an example is given to illustrate the method and results.
A Quaternary Geomagnetic Instability Time Scale
Singer, B. S.
2013-12-01
Reversals and excursions of Earth's geomagnetic field create marker horizons that are readily detected in sedimentary and volcanic rocks worldwide. An accurate and precise chronology of these geomagnetic field instabilities is fundamental to understanding several aspects of Quaternary climate, dynamo processes, and surface processes. For example, stratigraphic correlation between marine sediment and polar ice records of climate change across the cryospheres benefits from a highly resolved record of reversals and excursions. The temporal patterns of dynamo behavior may reflect physical interactions between the molten outer core and the solid inner core or lowermost mantle. These interactions may control reversal frequency and shape the weak magnetic fields that arise during successive dynamo instabilities. Moreover, weakening of the axial dipole during reversals and excursions enhances the production of cosmogenic isotopes that are used in sediment and ice core stratigraphy and surface exposure dating. The Geomagnetic Instability Time Scale (GITS) is based on the direct dating of transitional polarity states recorded by lava flows using the 40Ar/39Ar method, in parallel with astrochronologic age models of marine sediments in which O isotope and magnetic records have been obtained. A review of data from Quaternary lava flows and sediments yields a GITS comprising 10 polarity reversals and 27 excursions during the past 2.6 million years. Nine of the ten reversals bounding chrons and subchrons are associated with 40Ar/39Ar ages of transitionally-magnetized lava flows. The tenth, the Guass-Matuyama chron boundary, is tightly bracketed by 40Ar/39Ar dated ash deposits. Of the 27 well-documented excursions, 14 occurred during the Matuyama chron and 13 during the Brunhes chron; 19 have been dated directly using the 40Ar/39Ar method on transitionally-magnetized volcanic rocks and form the backbone of the GITS. Excursions are clearly not the rare phenomena once thought
Real-time PCR and pyrosequencing for differentiation of medically relevant Bartonella species.
Buss, Sarah N; Gebhardt, Linda L; Musser, Kimberlee A
2012-11-01
Multiple Bartonella species cause disease in humans. Although fast and accurate species differentiation could inform effective treatment interventions, species-level diagnosis of Bartonella infections is not typical. Here we describe a real-time PCR and pyrosequencing based algorithm for rapid differentiation of at least 11 medically relevant Bartonella spp.
Harvey-Thompson, A. J.; Sefkow, A. B.; Wei, M. S.; Nagayama, T.; Campbell, E. M.; Blue, B. E.; Heeter, R. F.; Koning, J. M.; Peterson, K. J.; Schmitt, A.
2016-11-01
We report experimental results and simulations showing efficient laser energy coupling into plasmas at conditions relevant to the magnetized liner inertial fusion (MagLIF) concept. In MagLIF, to limit convergence and increase the hydrodynamic stability of the implosion, the fuel must be efficiently preheated. To determine the efficiency and physics of preheating by a laser, an Ar plasma with ne/nc r i t˜0.04 is irradiated by a multi-ns, multi-kJ, 0.35-μm, phase-plate-smoothed laser at spot-averaged intensities ranging from 1.0 ×1014 to 2.5 ×1014W /c m2 and pulse widths from 2 to 10 ns. Time-resolved x-ray images of the laser-heated plasma are compared to two-dimensional radiation-hydrodynamic simulations that show agreement with the propagating emission front, a comparison that constrains laser energy deposition to the plasma. The experiments show that long-pulse, modest-intensity (I =1.5 ×1014W /c m2 ) beams can efficiently couple energy (˜82 % of the incident energy) to MagLIF-relevant long-length (9.5 mm) underdense plasmas. The demonstrated heating efficiency is significantly higher than is thought to have been achieved in early integrated MagLIF experiments [A. B. Sefkow et al., Phys. Plasmas 21, 072711 (2014), 10.1063/1.4890298].
Digital Library ImageRetrieval usingScale Invariant Feature and Relevance Vector Machine
Hongtao Zhang
2014-10-01
Full Text Available With the advance of digital library, the digital content develops with rich information connotation. Traditional information retrieval methods based on external characteristic and text description are unable to sufficientlyreveal and express the substance and semantic relation of multimedia information, and unable to fully reveal and describe the representative characteristics of information. Because of the abundant connotation of image content and the people’s abstract subjectivity in studying image content, the visual feature of the image is difficult to be described by key words. Therefore, this method not always can meet people’s needs, and the study of digital library image retrieval technique based on content is important to both academic research and application. At present, image retrieval methods are mainly based on the text and content, etc. But these existing algorithms have shortages, such as large errors and slow speeds. Motivated by the above fact, we in this paper propose a new approach based on relevance vector machine (RVM. The proposed approach first extracts the patch-level scale invariant image feature (SIFT, and then constructs the global features for images. The image feature is then delivered into RVM for retrieval. We evaluate the proposed approach on Corel dataset. The experimental result shows that the proposed method in this text has high accuracy when retrieves images.
Improving the local relevance of large scale water demand predictions: the way forward
Bernhard, Jeroen; Reynaud, Arnaud; de Roo, Ad
2016-04-01
Securing adequate availability of fresh water is of vital importance for socio-economic development of present and future Europe. Due to strong heterogeneity in climate conditions, some regions receive an abundant supply of water, where other areas almost completely depend on limited river discharge from upstream catchments. Furthermore, water demand differs greatly between regions due to differences in population density and local presence of intensive water using industries and agriculture. This results in many situations all across Europe where competition between water users translates into relative scarcity and economic damage. Additionally it is expected that inter-related economic and demographic developments, as well as climate change are to only further increase the need for efficient management of our water resources in the future. Successful policy making for such complex problems requires a good understanding of the system and reliable forecasting of conditions. The extent and complexity of the water use system however, stands in high contrast with the poor state of available data and lack of reliable predictions for this multi-disciplinary topic. Although the matching of available water to its demand is a European-wide problem, the amount of data with pan-European coverage is limited and usually with a national resolution at best. This is hindering researchers and policy makers because it usually makes large scale water demand predictions little relevant due to the strong regional heterogenic nature of the problem. We present in our study a first attempt of European-wide water demand predictions based on consistent regional data and econometric methods for the household and industry sector. We gathered data on water consumption, water prices and other relevant variables at the highest spatial detail available from national statistical offices and other organizational bodies. This database provides the most detailed up to date picture of present water
Local Observability of Systems on Time Scales
Zbigniew Bartosiewicz
2013-01-01
unified way using the language of real analytic geometry, ideals of germs of analytic functions, and their real radicals. It is shown that some properties related to observability are preserved under various discretizations of continuous-time systems.
Rosenberg, M. J.; Solodov, A. A.; Seka, W.; Myatt, J. F.; Regan, S. P.; Hohenberger, M.; Epstein, R.; Froula, D. H.; Radha, P. B.; Michel, P. A.; Moody, J. D.; Masse, L.; Goyon, C.; Turnbull, D. P.; Barrios, M. A.; Bates, J. W.; Schmitt, A. J.
2016-10-01
The first experiments at the National Ignition Facility to probe laser-plasma interactions and the hot electron production at scale lengths relevant to direct-drive ignition are reported. The irradiation on one side of planar CH foils generated a plasma at the quarter-critical surface with predicted density scale lengths of Ln 600 μm, measured electron temperatures of Te 3.5 to 4.0 keV, and overlapped laser intensities of I 6 to 15 ×1014W/cm2. Optical emission from stimulated Raman scattering (SRS) and at ω/2 are correlated with the time-dependent hard x-ray signal. The fraction of laser energy converted to hot electrons increased from 0.5 % to 2.3 % as the laser intensity increased from 6 to 15 ×1014W/cm2, while the hot electron temperature was nearly constant around 40 to 50 keV. Only a sharp red-shifted feature is observed around ω/2, and both refracted and sidescattered SRS are detected, suggesting that multibeam SRS contributes to, and may even dominate, hot-electron production. These results imply a diminished presence of two-plasmon decay relative to SRS at these conditions, which has implications for hot-electron preheat mitigation strategies for direct-drive ignition. This work is supported by the DOE NNSA under Award Number DE-NA0001944.
Scale-dependent intrinsic entropies of complex time series.
Yeh, Jia-Rong; Peng, Chung-Kang; Huang, Norden E
2016-04-13
Multi-scale entropy (MSE) was developed as a measure of complexity for complex time series, and it has been applied widely in recent years. The MSE algorithm is based on the assumption that biological systems possess the ability to adapt and function in an ever-changing environment, and these systems need to operate across multiple temporal and spatial scales, such that their complexity is also multi-scale and hierarchical. Here, we present a systematic approach to apply the empirical mode decomposition algorithm, which can detrend time series on various time scales, prior to analysing a signal's complexity by measuring the irregularity of its dynamics on multiple time scales. Simulated time series of fractal Gaussian noise and human heartbeat time series were used to study the performance of this new approach. We show that our method can successfully quantify the fractal properties of the simulated time series and can accurately distinguish modulations in human heartbeat time series in health and disease.
OSCILLATION FOR NONAUTONOMOUS NEUTRAL DYNAMIC DELAY EQUATIONS ON TIME SCALES
无
2006-01-01
The article is concerned with oscillation of nonautonomous neutral dynamic delay equations on time scales. Sufficient conditions are established for the existence of bounded positive solutions and for oscillation of all solutions of this equation. Some results extend known results for difference equations when the time scale is the set Z+ of positive integers and for differential equations when the time scale is the set R of real numbers.
Nuclear disassembly time scales using space time correlations
Durand, D.; Colin, J.; Lecolley, J.F.; Meslin, C.; Aboufirassi, M.; Bougault, R.; Brou, R. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire; Bilwes, B.; Cosmo, F. [Strasbourg-1 Univ., 67 (France); Galin, J. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); and others
1996-09-01
The lifetime, {tau}, with respect to multifragmentation of highly excited nuclei is deduced from the analysis of strongly damped Pb+Au collisions at 29 MeV/u. The method is based on the study of space-time correlations induced by `proximity` effects between fragments emitted by the two primary products of the reaction and gives the time between the re-separation of the two primary products and the subsequent multifragment decay of one partner. (author). 2 refs.
Altmoos, Michael; Henle, Klaus
2010-11-01
Habitat models for animal species are important tools in conservation planning. We assessed the need to consider several scales in a case study for three amphibian and two grasshopper species in the post-mining landscapes near Leipzig (Germany). The two species groups were selected because habitat analyses for grasshoppers are usually conducted on one scale only whereas amphibians are thought to depend on more than one spatial scale. First, we analysed how the preference to single habitat variables changed across nested scales. Most environmental variables were only significant for a habitat model on one or two scales, with the smallest scale being particularly important. On larger scales, other variables became significant, which cannot be recognized on lower scales. Similar preferences across scales occurred in only 13 out of 79 cases and in 3 out of 79 cases the preference and avoidance for the same variable were even reversed among scales. Second, we developed habitat models by using a logistic regression on every scale and for all combinations of scales and analysed how the quality of habitat models changed with the scales considered. To achieve a sufficient accuracy of the habitat models with a minimum number of variables, at least two scales were required for all species except for Bufo viridis, for which a single scale, the microscale, was sufficient. Only for the European tree frog ( Hyla arborea), at least three scales were required. The results indicate that the quality of habitat models increases with the number of surveyed variables and with the number of scales, but costs increase too. Searching for simplifications in multi-scaled habitat models, we suggest that 2 or 3 scales should be a suitable trade-off, when attempting to define a suitable microscale.
Aspects of the optical system relevant for the KM3NeT timing calibration
Kieft Gerard
2016-01-01
Full Text Available KM3NeT is a future research infrastructure in the Mediterranean Sea housing the large Cherenkov telescope arrays of optical modules for neutrino detection. The detector control and data transmission system is based on fibre optical technology. For timing calibration of the detector signals the optical system is used to send and fan-out an onshore clock signal, derived from a GPS receiver, to all optical modules in the deep sea. The optical modules use this clock signal to time stamp the light pulses detected by the photomultipliers inside the modules. The delay time between the GPS clock on shore and the clock in each optical module is measured with sub-nanosecond precision using a White Rabbit based timing calibration system. The aspects of the optical system relevant for the timing calibration and the quantification of their effect will be presented.
Development and Preliminary Validation of the Time Management for Exercise Scale
Hellsten, Laurie-ann M.; Rogers, W. Todd
2009-01-01
The purpose of this study was to collect preliminary validity evidence for a time management scale for exercise. An initial pool of 91 items was developed from existing literature. Ten exercise/health psychologists evaluated each of the items in terms of relevance and representativeness. Forty-nine items met all criteria. Exploratory factor…
Development and Preliminary Validation of the Time Management for Exercise Scale
Hellsten, Laurie-ann M.; Rogers, W. Todd
2009-01-01
The purpose of this study was to collect preliminary validity evidence for a time management scale for exercise. An initial pool of 91 items was developed from existing literature. Ten exercise/health psychologists evaluated each of the items in terms of relevance and representativeness. Forty-nine items met all criteria. Exploratory factor…
Bounds of Certain Dynamic Inequalities on Time Scales
Deepak B. Pachpatte
2014-10-01
Full Text Available In this paper we study explicit bounds of certain dynamic integral inequalities on time scales. These estimates give the bounds on unknown functions which can be used in studying the qualitative aspects of certain dynamic equations. Using these inequalities we prove the uniqueness of some partial integro-differential equations on time scales.
Temperature dependence of fluctuation time scales in spin glasses
Kenning, Gregory G.; Bowen, J.; Sibani, Paolo;
2010-01-01
Using a series of fast cooling protocols we have probed aging effects in the spin glass state as a function of temperature. Analyzing the logarithmic decay found at very long time scales within a simple phenomenological barrier model, leads to the extraction of the fluctuation time scale of the s...
Real-time inference of word relevance from electroencephalogram and eye gaze
Wenzel, M. A.; Bogojeski, M.; Blankertz, B.
2017-10-01
Objective. Brain-computer interfaces can potentially map the subjective relevance of the visual surroundings, based on neural activity and eye movements, in order to infer the interest of a person in real-time. Approach. Readers looked for words belonging to one out of five semantic categories, while a stream of words passed at different locations on the screen. It was estimated in real-time which words and thus which semantic category interested each reader based on the electroencephalogram (EEG) and the eye gaze. Main results. Words that were subjectively relevant could be decoded online from the signals. The estimation resulted in an average rank of 1.62 for the category of interest among the five categories after a hundred words had been read. Significance. It was demonstrated that the interest of a reader can be inferred online from EEG and eye tracking signals, which can potentially be used in novel types of adaptive software, which enrich the interaction by adding implicit information about the interest of the user to the explicit interaction. The study is characterised by the following novelties. Interpretation with respect to the word meaning was necessary in contrast to the usual practice in brain-computer interfacing where stimulus recognition is sufficient. The typical counting task was avoided because it would not be sensible for implicit relevance detection. Several words were displayed at the same time, in contrast to the typical sequences of single stimuli. Neural activity was related with eye tracking to the words, which were scanned without restrictions on the eye movements.
Forecasting Electrical Load Using a Multi-time-scale Approach
RINGWOOD John; Murray, F.T.
1999-01-01
This paper describes the application of a multi-time-scale technique to the modelling and forecasting of short-term electrical load. The multi-time-scale technique is based on adjusting the underlying short sampling period forecast time series with specific target points and possible aggregated demand. This allows not only improvement of the short sampling period forecast, but also focuses on weighting the accuracy of the forecast at certain critical points e.g. the ov...
Liquidity spillover in international stock markets through distinct time scales.
Righi, Marcelo Brutti; Vieira, Kelmara Mendes
2014-01-01
This paper identifies liquidity spillovers through different time scales based on a wavelet multiscaling method. We decompose daily data from U.S., British, Brazilian and Hong Kong stock markets indices in order to calculate the scale correlation between their illiquidities. The sample is divided in order to consider non-crisis, sub-prime crisis and Eurozone crisis. We find that there are changes in correlations of distinct scales and different periods. Association in finest scales is smaller than in coarse scales. There is a rise on associations in periods of crisis. In frequencies, there is predominance for significant distinctions involving the coarsest scale, while for crises periods there is predominance for distinctions on the finest scale.
Extreme reaction times determine fluctuation scaling in human color vision
Medina, José M.; Díaz, José A.
2016-11-01
In modern mental chronometry, human reaction time defines the time elapsed from stimulus presentation until a response occurs and represents a reference paradigm for investigating stochastic latency mechanisms in color vision. Here we examine the statistical properties of extreme reaction times and whether they support fluctuation scaling in the skewness-kurtosis plane. Reaction times were measured for visual stimuli across the cardinal directions of the color space. For all subjects, the results show that very large reaction times deviate from the right tail of reaction time distributions suggesting the existence of dragon-kings events. The results also indicate that extreme reaction times are correlated and shape fluctuation scaling over a wide range of stimulus conditions. The scaling exponent was higher for achromatic than isoluminant stimuli, suggesting distinct generative mechanisms. Our findings open a new perspective for studying failure modes in sensory-motor communications and in complex networks.
Alma-Ata 30 years on: revolutionary, relevant, and time to revitalise.
Lawn, Joy E; Rohde, Jon; Rifkin, Susan; Were, Miriam; Paul, Vinod K; Chopra, Mickey
2008-09-13
In this paper, we revisit the revolutionary principles-equity, social justice, and health for all; community participation; health promotion; appropriate use of resources; and intersectoral action-raised by the 1978 Alma-Ata Declaration, a historic event for health and primary health care. Old health challenges remain and new priorities have emerged (eg, HIV/AIDS, chronic diseases, and mental health), ensuring that the tenets of Alma-Ata remain relevant. We examine 30 years of changes in global policy to identify the lessons learned that are of relevance today, particularly for accelerated scale-up of primary health-care services necessary to achieve the Millennium Development Goals, the modern iteration of the "health for all" goals. Health has moved from under-investment, to single disease focus, and now to increased funding and multiple new initiatives. For primary health care, the debate of the past two decades focused on selective (or vertical) versus comprehensive (horizontal) delivery, but is now shifting towards combining the strengths of both approaches in health systems. Debates of community versus facility-based health care are starting to shift towards building integrated health systems. Achievement of high and equitable coverage of integrated primary health-care services requires consistent political and financial commitment, incremental implementation based on local epidemiology, use of data to direct priorities and assess progress, especially at district level, and effective linkages with communities and non-health sectors. Community participation and intersectoral engagement seem to be the weakest strands in primary health care. Burgeoning task lists for primary health-care workers require long-term human resource planning and better training and supportive supervision. Essential drugs policies have made an important contribution to primary health care, but other appropriate technology lags behind. Revitalisng Alma-Ata and learning from three
The gluino-glue particle and relevant scales for the simulations of supersymmetric Yang-Mills theory
Bergner, Georg; Münster, Gernot; Sandbrink, Dirk; Özugurel, Umut D
2012-01-01
Supersymmetric Yang-Mills theory is in several respects different from QCD and pure Yang-Mills theory. Therefore, a reinvestigation of the scales, at which finite size effects and lattice artifacts become relevant, is necessary. Both, finite size effects and lattice artifacts, induce a breaking of supersymmetry. In view of the unexpected mass gap between bosonic and fermionic particles an estimation of these effects is essential.
Scaling of the Time Dependent SGEMP Boundary Layer.
constant in time or rises like any given power of time a single solution suffices for all fluxes. For a more realistic time history with a finite FWHM, the equations reduce to a single parameter family, the parameter being the ratio of the pulse FWHM to the characteristic plasma period. For the time behavior, the unit of time is taken as the FWHM. Both the scaled Boltzmann Equation and Newton’s Equations are
AFSC/ABL: Ugashik sockeye salmon scale time series
National Oceanic and Atmospheric Administration, Department of Commerce — A time series of scale samples (1956 b?? 2002) collected from adult sockeye salmon returning to Ugashik River were retrieved from the Alaska Department of Fish and...
The limit order book on different time scales
Eisler, Zoltan; Lillo, Fabrizio
2007-01-01
Financial markets can be described on several time scales. We use data from the limit order book of the London Stock Exchange (LSE) to compare how the fluctuation dominated microstructure crosses over to a more systematic global behavior.
The limit order book on different time scales
Eisler, Zoltán; Kertész, János; Lillo, Fabrizio
2007-06-01
Financial markets can be described on several time scales. We use data from the limit order book of the London Stock Exchange (LSE) to compare how the fluctuation dominated microstructure crosses over to a more systematic global behavior.
BOUNDARY VALUE PROBLEM TO DYNAMIC EQUATION ON TIME SCALE
无
2011-01-01
In this paper we consider a nonlinear first-order boundary value problem on a time scale. The existence results of three positive solutions are obtained using fixed point theorems. Finally,examples are presented to illustrate the main results.
AFSC/ABL: Naknek sockeye salmon scale time series
National Oceanic and Atmospheric Administration, Department of Commerce — A time series of scale samples (1956 2002) collected from adult sockeye salmon returning to Naknek River were retrieved from the Alaska Department of Fish and Game....
Signatures of discrete scale invariance in Dst time series
Balasis, Georgios; Papadimitriou, Constantinos; Daglis, Ioannis A.; Anastasiadis, Anastasios; Athanasopoulou, Labrini; Eftaxias, Konstantinos
2011-07-01
Self-similar systems are characterized by continuous scale invariance and, in response, the existence of power laws. However, a significant number of systems exhibits discrete scale invariance (DSI) which in turn leads to log-periodic corrections to scaling that decorate the pure power law. Here, we present the results of a search of log-periodic corrections to scaling in the squares of Dst index increments which are taken as proxies of the energy dissipation rate in the magnetosphere. We show that Dst time series exhibit DSI and discuss the consequence of this feature, as well as the possible implications of Dst DSI on space weather forecasting efforts.
Characteristic Time Scales of Characteristic Magmatic Processes and Systems
Marsh, B. D.
2004-05-01
Every specific magmatic process, regardless of spatial scale, has an associated characteristic time scale. Time scales associated with crystals alone are rates of growth, dissolution, settling, aggregation, annealing, and nucleation, among others. At the other extreme are the time scales associated with the dynamics of the entire magmatic system. These can be separated into two groups: those associated with system genetics (e.g., the production and transport of magma, establishment of the magmatic system) and those due to physical characteristics of the established system (e.g., wall rock failure, solidification front propagation and instability, porous flow). The detailed geometry of a specific magmatic system is particularly important to appreciate; although generic systems are useful, care must be taken to make model systems as absolutely realistic as possible. Fuzzy models produce fuzzy science. Knowledge of specific time scales is not necessarily useful or meaningful unless the hierarchical context of the time scales for a realistic magmatic system is appreciated. The age of a specific phenocryst or ensemble of phenocrysts, as determined from isotopic or CSD studies, is not meaningful unless something can be ascertained of the provenance of the crystals. For example, crystal size multiplied by growth rate gives a meaningful crystal age only if it is from a part of the system that has experienced semi-monotonic cooling prior to chilling; crystals entrained from a long-standing cumulate bed that were mechanically sorted in ascending magma may not reveal this history. Ragged old crystals rolling about in the system for untold numbers of flushing times record specious process times, telling more about the noise in the system than the life of typical, first generation crystallization processes. The most helpful process-related time scales are those that are known well and that bound or define the temporal style of the system. Perhaps the most valuable of these
The relevance of non-generic events in scale space models
Kuijper, Arjan; Florack, L.
2002-01-01
In order to investigate the deep structure of Gaussian scale space images, one needs to understand the behaviour of spatial critical points under the influence of blurring. We show how the mathematical framework of catastrophe theory can be used to describe and model the behaviour of critical point
Exponentials and Laplace transforms on nonuniform time scales
Ortigueira, Manuel D.; Torres, Delfim F. M.; Trujillo, Juan J.
2016-10-01
We formulate a coherent approach to signals and systems theory on time scales. The two derivatives from the time-scale calculus are used, i.e., nabla (forward) and delta (backward), and the corresponding eigenfunctions, the so-called nabla and delta exponentials, computed. With these exponentials, two generalised discrete-time Laplace transforms are deduced and their properties studied. These transforms are compatible with the standard Laplace and Z transforms. They are used to study discrete-time linear systems defined by difference equations. These equations mimic the usual continuous-time equations that are uniformly approximated when the sampling interval becomes small. Impulse response and transfer function notions are introduced. This implies a unified mathematical framework that allows us to approximate the classic continuous-time case when the sampling rate is high or to obtain the standard discrete-time case, based on difference equations, when the time grid becomes uniform.
Inferring Patterns in Network Traffic: Time Scales and Variations
2014-10-21
2014 Carnegie Mellon University Inferring Patterns in Network Traffic : Time Scales and Variation Soumyo Moitra smoitra@sei.cmu.edu...number. 1. REPORT DATE 21 OCT 2014 2. REPORT TYPE N/A 3. DATES COVERED 4. TITLE AND SUBTITLE Inferring Patterns in Network Traffic : Time...method and metrics for Situational Awareness • SA Monitoring trends and changes in traffic • Analysis over time Time series data analysis • Metrics
Time-Scale and Time-Frequency Analyses of Irregularly Sampled Astronomical Time Series
S. Roques
2005-09-01
Full Text Available We evaluate the quality of spectral restoration in the case of irregular sampled signals in astronomy. We study in details a time-scale method leading to a global wavelet spectrum comparable to the Fourier period, and a time-frequency matching pursuit allowing us to identify the frequencies and to control the error propagation. In both cases, the signals are first resampled with a linear interpolation. Both results are compared with those obtained using Lomb's periodogram and using the weighted waveletZ-transform developed in astronomy for unevenly sampled variable stars observations. These approaches are applied to simulations and to light variations of four variable stars. This leads to the conclusion that the matching pursuit is more efficient for recovering the spectral contents of a pulsating star, even with a preliminary resampling. In particular, the results are almost independent of the quality of the initial irregular sampling.
The relevance of cartographic scale in interactive and multimedia cartographic information systems
Mirjanka Lechthaler
2004-09-01
Full Text Available The application of new technologies in the processes of gathering, analysing, transforming, visualizing and communicating of space data and geoinformation offers a great challenge for cartography. Cartographic information provision as described in several cartographic models, which is included in cartographic information systems depend on the graphical presentation/visualization at certain scales. That necessitates a need to define the capacity or content borders (geometry and semantic for cognition and communication. However, currently we need and use maps as a vehicle for transportation of spatial and temporal information. Graphic constructions of geoanalogies, linked with interaction, multimedia sequences and animations, support effective geocommunication, bridging the gaps imposed by having to work at pre-defined scales. This paper illustrates two interactive information systems, which were conceptualised and prototyped at the Institute of Cartography and Geomedia Technique, Vienna University of Technology.
Time scale bias in erosion rates of glaciated landscapes.
Ganti, Vamsi; von Hagke, Christoph; Scherler, Dirk; Lamb, Michael P; Fischer, Woodward W; Avouac, Jean-Philippe
2016-10-01
Deciphering erosion rates over geologic time is fundamental for understanding the interplay between climate, tectonic, and erosional processes. Existing techniques integrate erosion over different time scales, and direct comparison of such rates is routinely done in earth science. On the basis of a global compilation, we show that erosion rate estimates in glaciated landscapes may be affected by a systematic averaging bias that produces higher estimated erosion rates toward the present, which do not reflect straightforward changes in erosion rates through time. This trend can result from a heavy-tailed distribution of erosional hiatuses (that is, time periods where no or relatively slow erosion occurs). We argue that such a distribution can result from the intermittency of erosional processes in glaciated landscapes that are tightly coupled to climate variability from decadal to millennial time scales. In contrast, we find no evidence for a time scale bias in spatially averaged erosion rates of landscapes dominated by river incision. We discuss the implications of our findings in the context of the proposed coupling between climate and tectonics, and interpreting erosion rate estimates with different averaging time scales through geologic time.
Time scales and species coexistence in chaotic flows
Galla, Tobias
2016-01-01
Empirical observations in marine ecosystems have suggested a balance of biological and advection time scales as a possible explanation of species coexistence. To characterise this scenario, we measure the time to fixation in neutrally evolving populations in chaotic flows. Contrary to intuition the variation of time scales does not interpolate straightforwardly between the no-flow and well-mixed limits; instead we find that fixation is the slowest at intermediate Damk\\"ohler numbers, indicating long-lasting coexistence of species. Our analysis shows that this slowdown is due to spatial organisation on an increasingly modularised network. We also find that diffusion can either slow down or speed up fixation, depending on the relative time scales of flow and evolution.
Grasping Deep Time with Scaled Space in Personal Environs
Jacobsen, B. H.
2014-01-01
the history of geology and evolution. The present project differs from these examples in that the scaling of time is fixed, and the scale is defined so that 1 mm represents the life expectancy of a young person, i.e. 100 years. At this scale, written history fits on a credit card, 1 m measures the time...... of modern man, the age of dinosaurs ended at 650 m and the Big Bang is 137 km away. This choice obviously makes mental calculations easy, and all of time fits inside a geographical area of moderate size and so helps the citizen gain ownership to this learning tool and hence to time. The idea was tested...
Auroral Substorm Time Scales: Seasonal and IMF Variations
Chua, D.; Parks, G. K.; Brittnacher, M.; Germany, G. A.; Spann, J. F.; Six, N. Frank (Technical Monitor)
2002-01-01
The time scales and phases of auroral substorm, activity are quantied in this study using the hemispheric power computed from Polar Ultraviolet Imager (UVI) images. We have applied this technique to several hundred substorm events and we are able to quantify how the characterist act, of substorms vary with season and IMF Bz orientation. We show that substorm time scales vary more strongly with season than with IMF Bz orientation. The recovery time for substorm. activity is well ordered by whether or not the nightside oral zone is sunlit. The recovery time scales for substorms occurring in the winter and equinox periods are similar and are both roughly a factor of two longer than in summer when the auroral oval is sunlit. Our results support the hypothesis that the ionosphere plays an active role in governing the dynamics of the aurora.
Tunneling time scale of under-the-barrier forerunners
García-Calderón, G; Garcia-Calderon, Gaston; Villavicencio, Jorge
2002-01-01
Time-dependent analytical solutions to Schr\\"{o}dinger's equation with quantum shutter initial conditions are used to investigate the issue of the tunneling time of forerunners in rectangular potential barriers. By using a time-frequency analysis, we find the existence of a regime characterized by the opacity of the barrier, where the maximum peak of a forerunner in time domain corresponds to a genuine tunneling process. The corresponding time scale represents the tunneling time of the forerunner through the classically forbidden region.
Relevant Norms of Holy Places and Times in Three Sacred Books
Mohsenian, M
2011-01-01
Full Text Available Basically speaking, saintliness is considered as a commented and valued issue allotting to religion realm which without the presence of such a meaning, no religion is worthy of its name.This article aims to consider the normative prepositions related to holy places and times in three sacred books : Quran, Pentateuch, and Gospel with their similarities and differences. A specific software program is used with quantitative and qualitative research method to process and analyze the data by means of a profound content analysis method.As a result of searching in these three sacred books, 10396 normative propositions were found which are categorized in 123 sections. One of these sections includes 295 prepositions with the content of holy places and the other one has 301 prepositions with the content of holy times.Therefore, 5.7 percent of the dos and don'ts of these three books presented in tables of this article is based on the norms of holy places and times. According to these tables, Pentateuch considers do's and don'ts in our relation and holy places as well as us and holy times more than the two other books. In a section of holy places, the share of normative prepositions related to us and sacred objects is more in Pentateuch rather than Quran and Gospel. However Gospel compared to the other books has more relevant norms related to places of worship like churches and synagogues. Additionally, the least normative propositions related to us and holy times could be found in Gospel. The normative prepositions related to religiously prohibited months are just seen in Quran.This article lists 596 normative propositions with their identity numbers by representing the exact address of the source of verses.Eventually, a symmetry model of fivefold contents of places and times norms in three sacred books is computed and designed. Factors to be taken in to accounts in this model are reaching to coefficient correlation of 0.7 between the contents of Eids and
Relevant Norms of Holy Places and Times in Three Sacred Books
Naser Bahonar
2011-08-01
Full Text Available Basically speaking, saintliness is considered as a commented and valued issue allotting to religion realm which without the presence of such a meaning, no religion is worthy of its name. This article aims to consider the normative prepositions related to holy places and times in three sacred books : Quran, Pentateuch, and Gospel with their similarities and differences. A specific software program is used with quantitative and qualitative research method to process and analyze the data by means of a profound content analysis method.As a result of searching in these three sacred books, 10396 normative propositions were found which are categorized in 123 sections. One of these sections includes 295 prepositions with the content of holy places and the other one has 301 prepositions with the content of holy times. Therefore, 5.7 percent of the dos and don'ts of these three books presented in tables of this article is based on the norms of holy places and times. According to these tables, Pentateuch considers do's and don'ts in our relation and holy places as well as us and holy times more than the two other books. In a section of holy places, the share of normative prepositions related to us and sacred objects is more in Pentateuch rather than Quran and Gospel. However Gospel compared to the other books has more relevant norms related to places of worship like churches and synagogues. Additionally, the least normative propositions related to us and holy times could be found in Gospel. The normative prepositions related to religiously prohibited months are just seen in Quran.This article lists 596 normative propositions with their identity numbers by representing the exact address of the source of verses. Eventually, a symmetry model of fivefold contents of places and times norms in three sacred books is computed and designed. Factors to be taken in to accounts in this model are reaching to coefficient correlation of 0.7 between the contents
Relevant Norms of Holy Places and Times in Three Sacred Books
Mahdi Mohsenian
2011-09-01
Full Text Available Basically speaking, saintliness is considered as a commented and valued issue allotting to religion realm which without the presence of such a meaning, no religion is worthy of its name. This article aims to consider the normative prepositions related to holy places and times in three sacred books : Quran, Pentateuch, and Gospel with their similarities and differences. A specific software program is used with quantitative and qualitative research method to process and analyze the data by means of a profound content analysis method.As a result of searching in these three sacred books, 10396 normative propositions were found which are categorized in 123 sections. One of these sections includes 295 prepositions with the content of holy places and the other one has 301 prepositions with the content of holy times. Therefore, 5.7 percent of the dos and don'ts of these three books presented in tables of this article is based on the norms of holy places and times. According to these tables, Pentateuch considers do's and don'ts in our relation and holy places as well as us and holy times more than the two other books. In a section of holy places, the share of normative prepositions related to us and sacred objects is more in Pentateuch rather than Quran and Gospel. However Gospel compared to the other books has more relevant norms related to places of worship like churches and synagogues. Additionally, the least normative propositions related to us and holy times could be found in Gospel. The normative prepositions related to religiously prohibited months are just seen in Quran.This article lists 596 normative propositions with their identity numbers by representing the exact address of the source of verses. Eventually, a symmetry model of fivefold contents of places and times norms in three sacred books is computed and designed. Factors to be taken in to accounts in this model are reaching to coefficient correlation of 0.7 between the
Thermodynamics constrains allometric scaling of optimal development time in insects.
Michael E Dillon
Full Text Available Development time is a critical life-history trait that has profound effects on organism fitness and on population growth rates. For ectotherms, development time is strongly influenced by temperature and is predicted to scale with body mass to the quarter power based on 1 the ontogenetic growth model of the metabolic theory of ecology which describes a bioenergetic balance between tissue maintenance and growth given the scaling relationship between metabolism and body size, and 2 numerous studies, primarily of vertebrate endotherms, that largely support this prediction. However, few studies have investigated the allometry of development time among invertebrates, including insects. Abundant data on development of diverse insects provides an ideal opportunity to better understand the scaling of development time in this ecologically and economically important group. Insects develop more quickly at warmer temperatures until reaching a minimum development time at some optimal temperature, after which development slows. We evaluated the allometry of insect development time by compiling estimates of minimum development time and optimal developmental temperature for 361 insect species from 16 orders with body mass varying over nearly 6 orders of magnitude. Allometric scaling exponents varied with the statistical approach: standardized major axis regression supported the predicted quarter-power scaling relationship, but ordinary and phylogenetic generalized least squares did not. Regardless of the statistical approach, body size alone explained less than 28% of the variation in development time. Models that also included optimal temperature explained over 50% of the variation in development time. Warm-adapted insects developed more quickly, regardless of body size, supporting the "hotter is better" hypothesis that posits that ectotherms have a limited ability to evolutionarily compensate for the depressing effects of low temperatures on rates of
Common scaling patterns in intertrade times of U. S. stocks.
Ivanov, Plamen Ch; Yuen, Ainslie; Podobnik, Boris; Lee, Youngki
2004-05-01
We analyze the sequence of time intervals between consecutive stock trades of thirty companies representing eight sectors of the U.S. economy over a period of 4 yrs. For all companies we find that: (i) the probability density function of intertrade times may be fit by a Weibull distribution, (ii) when appropriately rescaled the probability densities of all companies collapse onto a single curve implying a universal functional form, (iii) the intertrade times exhibit power-law correlated behavior within a trading day and a consistently greater degree of correlation over larger time scales, in agreement with the correlation behavior of the absolute price returns for the corresponding company, and (iv) the magnitude series of intertrade time increments is characterized by long-range power-law correlations suggesting the presence of nonlinear features in the trading dynamics, while the sign series is anticorrelated at small scales. Our results suggest that independent of industry sector, market capitalization and average level of trading activity, the series of intertrade times exhibit possibly universal scaling patterns, which may relate to a common mechanism underlying the trading dynamics of diverse companies. Further, our observation of long-range power-law correlations and a parallel with the crossover in the scaling of absolute price returns for each individual stock, support the hypothesis that the dynamics of transaction times may play a role in the process of price formation.
无
2006-01-01
In this paper, using the theory of topological degree and Liapunov functional methods, the authors study the competitive neural networks with time delays and different time scales and present some criteria of global robust stability for this neural network model.
Validation of time-lagged ensemble forecasts relevant for predicting aircraft wake vortices
Dengler, Klaus; Anger, Johanna [DLR, Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere; Keil, Christian [Ludwig-Maximilians-Univ. Muenchen (Germany). Meteorologisches Inst.
2011-12-15
Time-Lagged Ensemble (TLE) forecasts of the high-resolution model COSMO-FRA with a horizontal resolution of 2.8 km, an hourly update cycle and a lead time of six hours are validated against measurements of a Wind-Temperature Radar (WTR) for three cases representing different weather regimes: a frontal passage, a stormy situation and a high pressure system. Forecasts and measurements are available at high temporal resolution every 10 minutes. The present study focuses on parameters relevant for forecasting aircraft wake vortices, namely wind, virtual potential temperature and Turbulent Kinetic Energy (TKE) for altitudes below 1600 m. When compared with a deterministic run started once a day at 00 UTC with a lead time of 24 h a reduction of forecast error in the first two forecast hours is visible for all wind components. For wind speed at low levels around 400 m this reduction is of order 1.7 ms{sup -1} for the 1-hour forecast member and 0.9 ms{sup -1} for the equally weighted ensemble mean depending on weather situation. TLE forecasts of virtual potential temperature show an improvement of about 1 K except for the high pressure system while forecast errors of TKE are reduced in all cases below 900 m. Since no data assimilation is used presently in COSMO-FRA, the improvements of the forecasts are the result of the hourly update cycle which benefits from most recent initial conditions provided by the COSMO-EU analysis. The results of this study may contribute to improve the quality of wake vortex predictions and encourage the assimilation of temporal high resolution wind data into COSMO-FRA to further improve the very short range forecasts. (orig.)
Physical time scale in kinetic Monte Carlo simulations of continuous-time Markov chains.
Serebrinsky, Santiago A
2011-03-01
We rigorously establish a physical time scale for a general class of kinetic Monte Carlo algorithms for the simulation of continuous-time Markov chains. This class of algorithms encompasses rejection-free (or BKL) and rejection (or "standard") algorithms. For rejection algorithms, it was formerly considered that the availability of a physical time scale (instead of Monte Carlo steps) was empirical, at best. Use of Monte Carlo steps as a time unit now becomes completely unnecessary.
Time-dependent scaling patterns in high frequency financial data
Nava, Noemi; Di Matteo, Tiziana; Aste, Tomaso
2016-10-01
We measure the influence of different time-scales on the intraday dynamics of financial markets. This is obtained by decomposing financial time series into simple oscillations associated with distinct time-scales. We propose two new time-varying measures of complexity: 1) an amplitude scaling exponent and 2) an entropy-like measure. We apply these measures to intraday, 30-second sampled prices of various stock market indices. Our results reveal intraday trends where different time-horizons contribute with variable relative amplitudes over the course of the trading day. Our findings indicate that the time series we analysed have a non-stationary multifractal nature with predominantly persistent behaviour at the middle of the trading session and anti-persistent behaviour at the opening and at the closing of the session. We demonstrate that these patterns are statistically significant, robust, reproducible and characteristic of each stock market. We argue that any modelling, analytics or trading strategy must take into account these non-stationary intraday scaling patterns.
Evaluation of scaling invariance embedded in short time series.
Pan, Xue; Hou, Lei; Stephen, Mutua; Yang, Huijie; Zhu, Chenping
2014-01-01
Scaling invariance of time series has been making great contributions in diverse research fields. But how to evaluate scaling exponent from a real-world series is still an open problem. Finite length of time series may induce unacceptable fluctuation and bias to statistical quantities and consequent invalidation of currently used standard methods. In this paper a new concept called correlation-dependent balanced estimation of diffusion entropy is developed to evaluate scale-invariance in very short time series with length ~10(2). Calculations with specified Hurst exponent values of 0.2,0.3,...,0.9 show that by using the standard central moving average de-trending procedure this method can evaluate the scaling exponents for short time series with ignorable bias (≤0.03) and sharp confidential interval (standard deviation ≤0.05). Considering the stride series from ten volunteers along an approximate oval path of a specified length, we observe that though the averages and deviations of scaling exponents are close, their evolutionary behaviors display rich patterns. It has potential use in analyzing physiological signals, detecting early warning signals, and so on. As an emphasis, the our core contribution is that by means of the proposed method one can estimate precisely shannon entropy from limited records.
Mixing Time Scales in a Supernova-Driven Interstellar Medium
D'Avillez, M A; Avillez, Miguel A. de; Low, Mordecai-Mark Mac
2002-01-01
We study the mixing of chemical species in the interstellar medium (ISM). Recent observations suggest that the distribution of species such as deuterium in the ISM may be far from homogeneous. This raises the question of how long it takes for inhomogeneities to be erased in the ISM, and how this depends on the length scale of the inhomogeneities. We added a tracer field to the three-dimensional, supernova-driven ISM model of Avillez (2000) to study mixing and dispersal in kiloparsec-scale simulations of the ISM with different supernova (SN) rates and different inhomogeneity length scales. We find several surprising results. Classical mixing length theory fails to predict the very weak dependence of mixing time on length scale that we find on scales of 25--500 pc. Derived diffusion coefficients increase exponentially with time, rather than remaining constant. The variance of composition declines exponentially, with a time constant of tens of Myr, so that large differences fade faster than small ones. The time ...
Modelling of UV radiation variations at different time scales
J. L. Borkowski
2008-03-01
Full Text Available Solar UV radiation variability in the period 1976–2006 is discussed with respect to the relative changes in the solar global radiation, ozone content, and cloudiness. All the variables were decomposed into separate components, representing variations of different time scales, using wavelet multi-resolution decomposition. The response of the UV radiation to the changes in the solar global radiation, ozone content, and cloudiness depends on the time scale, therefore, it seems reasonable to model separately the relation between UV and explanatory variables at different time scales. The wavelet components of the UV series are modelled and summed to obtain the fit of observed series. The results show that the coarser time scale components can be modelled with greater accuracy than fine scale components and the fitted values calculated by this method are in better agreement with observed values than values calculated by the regression method, in which variables were not decomposed. The residual standard error in the case of modelling with the use of wavelets is reduced by 14% in comparison to the regression method without decomposition.
Evaluation of scaling invariance embedded in short time series.
Xue Pan
Full Text Available Scaling invariance of time series has been making great contributions in diverse research fields. But how to evaluate scaling exponent from a real-world series is still an open problem. Finite length of time series may induce unacceptable fluctuation and bias to statistical quantities and consequent invalidation of currently used standard methods. In this paper a new concept called correlation-dependent balanced estimation of diffusion entropy is developed to evaluate scale-invariance in very short time series with length ~10(2. Calculations with specified Hurst exponent values of 0.2,0.3,...,0.9 show that by using the standard central moving average de-trending procedure this method can evaluate the scaling exponents for short time series with ignorable bias (≤0.03 and sharp confidential interval (standard deviation ≤0.05. Considering the stride series from ten volunteers along an approximate oval path of a specified length, we observe that though the averages and deviations of scaling exponents are close, their evolutionary behaviors display rich patterns. It has potential use in analyzing physiological signals, detecting early warning signals, and so on. As an emphasis, the our core contribution is that by means of the proposed method one can estimate precisely shannon entropy from limited records.
Synthesis of medicinally relevant terpenes: reducing the cost and time of drug discovery.
Jansen, Daniel J; Shenvi, Ryan A
2014-06-01
Terpenoids constitute a significant fraction of molecules produced by living organisms that have found use in medicine and other industries. Problems associated with their procurement and adaptation for human use can be solved using chemical synthesis, which is an increasingly economical option in the modern era of chemistry. This article documents, by way of individual case studies, strategies for reducing the time and cost of terpene synthesis for drug discovery. A major trend evident in recent syntheses is that complex terpenes are increasingly realistic starting points for both medicinal chemistry campaigns and large-scale syntheses, at least in the context of the academic laboratory, and this trend will likely penetrate the commercial sector in the near future.
Time scales of crystal mixing in magma mushes
Schleicher, Jillian M.; Bergantz, George W.; Breidenthal, Robert E.; Burgisser, Alain
2016-02-01
Magma mixing is widely recognized as a means of producing compositional diversity and preconditioning magmas for eruption. However, the processes and associated time scales that produce the commonly observed expressions of magma mixing are poorly understood, especially under crystal-rich conditions. Here we introduce and exemplify a parameterized method to predict the characteristic mixing time of crystals in a crystal-rich magma mush that is subject to open-system reintrusion events. Our approach includes novel numerical simulations that resolve multiphase particle-fluid interactions. It also quantifies the crystal mixing by calculating both the local and system-wide progressive loss of the spatial correlation of individual crystals throughout the mixing region. Both inertial and viscous time scales for bulk mixing are introduced. Estimated mixing times are compared to natural examples and the time for basaltic mush systems to become well mixed can be on the order of 10 days.
Time scales for molecule formation by ion-molecule reactions
Langer, W. D.; Glassgold, A. E.
1976-01-01
Analytical solutions are obtained for nonlinear differential equations governing the time-dependence of molecular abundances in interstellar clouds. Three gas-phase reaction schemes are considered separately for the regions where each dominates. The particular case of CO, and closely related members of the Oh and CH families of molecules, is studied for given values of temperature, density, and the radiation field. Nonlinear effects and couplings with particular ions are found to be important. The time scales for CO formation range from 100,000 to a few million years, depending on the chemistry and regime. The time required for essentially complete conversion of C(+) to CO in the region where the H3(+) chemistry dominates is several million years. Because this time is longer than or comparable to dynamical time scales for dense interstellar clouds, steady-state abundances may not be observed in such clouds.
Short—Time Scaling of Variable Ordering of OBDDs
龙望宁; 闵应骅; 等
1997-01-01
A short-time scaling criterion of variable ordering of OBDDs is proposed.By this criterion it is easy and fast to determine which one is better when several variable orders are given,especially when they differ 10% or more in resulted BDD size from each other.An adaptive variable order selection method,based on the short-time scaling criterion,is also presented.The experimental results show that this method is efficient and it makes the heuristic variable ordering methods more practical.
Multiple time scales of fluvial processes—theory and applications
无
2011-01-01
Fluvial processes comprise water flow,sediment transport and bed evolution,which normally feature distinct time scales.The time scales of sediment transport and bed deformation relative to the flow essentially measure how fast sediment transport adapts to capacity region in line with local flow scenario and the bed deforms in comparison with the flow,which literally dictates if a capacity based and/or decoupled model is justified.This paper synthesizes the recently developed multiscale theory for sediment-l...
Dynamics symmetries of Hamiltonian system on time scales
Peng, Keke, E-mail: pengkeke88@126.com; Luo, Yiping, E-mail: zjstulyp@126.com [Department of Physics, Zhejiang Sci-Tech University, Hangzhou 310018 (China)
2014-04-15
In this paper, the dynamics symmetries of Hamiltonian system on time scales are studied. We study the symmetries and quantities based on the calculation of variation and Lie transformation group. Particular focus lies in: the Noether symmetry leads to the Noether conserved quantity and the Lie symmetry leads to the Noether conserved quantity if the infinitesimal transformations satisfy the structure equation. As the new application of result, at end of the article, we give a simple example of Noether symmetry and Lie symmetry on time scales.
Nonlinear triple-point problems on time scales
Douglas R. Anderson
2004-04-01
Full Text Available We establish the existence of multiple positive solutions to the nonlinear second-order triple-point boundary-value problem on time scales, $$displaylines{ u^{Delta abla}(t+h(tf(t,u(t=0, cr u(a=alpha u(b+delta u^Delta(a,quad eta u(c+gamma u^Delta(c=0 }$$ for $tin[a,c]subsetmathbb{T}$, where $mathbb{T}$ is a time scale, $eta, gamma, deltage 0$ with $Beta+gamma>0$, $0
Dynamics symmetries of Hamiltonian system on time scales
Peng, Keke; Luo, Yiping
2014-04-01
In this paper, the dynamics symmetries of Hamiltonian system on time scales are studied. We study the symmetries and quantities based on the calculation of variation and Lie transformation group. Particular focus lies in: the Noether symmetry leads to the Noether conserved quantity and the Lie symmetry leads to the Noether conserved quantity if the infinitesimal transformations satisfy the structure equation. As the new application of result, at end of the article, we give a simple example of Noether symmetry and Lie symmetry on time scales.
P. Döll
2010-05-01
Full Text Available River flow regimes, including long-term average flows, seasonality, low flows, high flows and other types of flow variability, play an important role for freshwater ecosystems. Thus, climate change affects freshwater ecosystems not only by increased temperatures but also by altered river flow regimes. However, with one exception, transferable quantitative relations between flow alterations and ecological responses have not yet been derived. While discharge decreases are generally considered to be detrimental for ecosystems, the effect of future discharge increases is unclear. As a first step towards a global-scale analysis of climate change impacts on freshwater ecosystems, we quantified the impact of climate change on five ecologically relevant river flow indicators, using the global water model WaterGAP 2.1g to simulate monthly time series of river discharge with a spatial resolution of 0.5 degrees. Four climate change scenarios based on two global climate models and two greenhouse gas emissions scenarios were evaluated.
We compared the impact of climate change by the 2050s to the impact of water withdrawals and dams on natural flow regimes that had occurred by 2002. Climate change was computed to alter seasonal flow regimes significantly (i.e. by more than 10% on 90% of the global land area (excluding Greenland and Antarctica, as compared to only one quarter of the land area that had suffered from significant seasonal flow regime alterations due to dams and water withdrawals. Due to climate change, the timing of the maximum mean monthly river discharge will be shifted by at least one month on one third on the global land area, more often towards earlier months (mainly due to earlier snowmelt. Dams and withdrawals had caused comparable shifts on less than 5% of the land area only. Long-term average annual river discharge is predicted to significantly increase on one half of the land area, and to significantly decrease on one quarter
P. Döll
2010-02-01
Full Text Available River flow regimes, including long-term average flows, seasonality, low flows, high flows and other types of flow variability, play an important role for freshwater ecosystems. Thus, climate change affects freshwater ecosystems not only by increased temperatures but also by altered river flow regimes. However, with one exception, transferable quantitative relations between flow alterations and ecosystem responses have not yet been derived. While discharge decreases are generally considered to be detrimental for ecosystems, the effect of future discharge increases is unclear. As a first step towards a global-scale analysis of climate change impacts on freshwater ecosystems, we quantified the impact of climate change on five ecologically relevant river flow indicators, using the global water model WaterGAP 2.1g to simulate monthly time series of river discharge with a spatial resolution of 0.5 degrees. Four climate change scenarios based on two global climate models and two greenhouse gas emissions scenarios were evaluated.
We compared the impact of climate change by the 2050s to the impact of water withdrawals and dams on natural flow regimes that had occurred by 2002. Climate change was computed to alter seasonal flow regimes significantly (i.e. by more than 10% on 90% of the global land area (excluding Greenland and Antarctica, as compared to only one quarter of the land area that had suffered from significant seasonal flow regime alterations due to dams and water withdrawals. Due to climate change, the timing of the maximum mean monthly river discharge will be shifted by at least one month on one third on the global land area, more often towards earlier months (mainly due to earlier snowmelt. Dams and withdrawals had caused comparable shifts on less than 5% of the land area only. Long-term average annual river discharge is predicted to significantly increase on one half of the land area, and to significantly decrease on one quarter
Florian Holon
Full Text Available Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m. It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures
Holon, Florian; Mouquet, Nicolas; Boissery, Pierre; Bouchoucha, Marc; Delaruelle, Gwenaelle; Tribot, Anne-Sophie; Deter, Julie
2015-01-01
Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast) or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m). It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica) at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity) are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures at a relevant
Holon, Florian; Mouquet, Nicolas; Boissery, Pierre; Bouchoucha, Marc; Delaruelle, Gwenaelle; Tribot, Anne-Sophie; Deter, Julie
2015-01-01
Ecosystem services provided by oceans and seas support most human needs but are threatened by human activities. Despite existing maps illustrating human impacts on marine ecosystems, information remains either large-scale but rough and insufficient for stakeholders (1 km² grid, lack of data along the coast) or fine-scale but fragmentary and heterogeneous in methodology. The objectives of this study are to map and quantify the main pressures exerted on near-coast marine ecosystems, at a large spatial scale though in fine and relevant resolution for managers (one pixel = 20 x 20 m). It focuses on the French Mediterranean coast (1,700 km of coastline including Corsica) at a depth of 0 to 80 m. After completing and homogenizing data presently available under GIS on the bathymetry and anthropogenic pressures but also on the seabed nature and ecosystem vulnerability, we provide a fine modeling of the extent and impacts of 10 anthropogenic pressures on marine habitats. The considered pressures are man-made coastline, boat anchoring, aquaculture, urban effluents, industrial effluents, urbanization, agriculture, coastline erosion, coastal population and fishing. A 1:10 000 continuous habitat map is provided considering 11 habitat classes. The marine bottom is mostly covered by three habitats: infralittoral soft bottom, Posidonia oceanica meadows and circalittoral soft bottom. Around two thirds of the bottoms are found within medium and medium high cumulative impact categories. Seagrass meadows are the most impacted habitats. The most important pressures (in area and intensity) are urbanization, coastal population, coastal erosion and man-made coastline. We also identified areas in need of a special management interest. This work should contribute to prioritize environmental needs, as well as enhance the development of indicators for the assessment of the ecological status of coastal systems. It could also help better apply and coordinate management measures at a relevant
Midfrontal theta tracks action monitoring over multiple interactive time scales.
Cohen, Michael X
2016-11-01
Quickly detecting and correcting mistakes is a crucial brain function. EEG studies have identified an idiosyncratic electrophysiological signature of online error correction, termed midfrontal theta. Midfrontal theta has so far been investigated over the fast time-scale of a few hundred milliseconds. But several aspects of behavior and brain activity unfold over multiple time scales, displaying "scale-free" dynamics that have been linked to criticality and optimal flexibility when responding to changing environmental demands. Here we used a novel line-tracking task to demonstrate that midfrontal theta is a transient yet non-phase-locked response that is modulated by task performance over at least three time scales: a few hundred milliseconds at the onset of a mistake, task performance over a fixed window of the previous 5s, and scale-free-like fluctuations over many tens of seconds. These findings provide novel evidence for a role of midfrontal theta in online behavioral adaptation, and suggest new approaches for linking EEG signatures of human executive functioning to its neurobiological underpinnings.
Separation of Time Scales in a Quantum Newton's Cradle
van den Berg, R.; Wouters, B.; Eliëns, S.; De Nardis, J.; Konik, R. M.; Caux, J.-S.
2016-06-01
We provide detailed modeling of the Bragg pulse used in quantum Newton's-cradle-like settings or in Bragg spectroscopy experiments for strongly repulsive bosons in one dimension. We reconstruct the postpulse time evolution and study the time-dependent local density profile and momentum distribution by a combination of exact techniques. We further provide a variety of results for finite interaction strengths using a time-dependent Hartree-Fock analysis and bosonization-refermionization techniques. Our results display a clear separation of time scales between rapid and trap-insensitive relaxation immediately after the pulse, followed by slow in-trap periodic behavior.
Satellite attitude prediction by multiple time scales method
Tao, Y. C.; Ramnath, R.
1975-01-01
An investigation is made of the problem of predicting the attitude of satellites under the influence of external disturbing torques. The attitude dynamics are first expressed in a perturbation formulation which is then solved by the multiple scales approach. The independent variable, time, is extended into new scales, fast, slow, etc., and the integration is carried out separately in the new variables. The theory is applied to two different satellite configurations, rigid body and dual spin, each of which may have an asymmetric mass distribution. The disturbing torques considered are gravity gradient and geomagnetic. Finally, as multiple time scales approach separates slow and fast behaviors of satellite attitude motion, this property is used for the design of an attitude control device. A nutation damping control loop, using the geomagnetic torque for an earth pointing dual spin satellite, is designed in terms of the slow equation.
Linear Scaling Real Time TDDFT in the CONQUEST Code
O'Rourke, Conn
2014-01-01
The real time formulation of Time Dependent Density Functional Theory (RT-TDDFT) is implemented in the linear scaling density functional theory code CONQEST. Proceeding through the propagation of the density matrix, as opposed to the Kohn-Sham orbitals, it is possible to reduced the computational workload. Imposing a cut-off on the density matrix the effort can be made to scale linearly with the size of the system under study. Propagation of the reduced density matrix in this manner provides direct access to the optical response of very large systems, which would be otherwise impractical to obtain using the standard formulations of TDDFT. We discuss our implementation and present several benchmark tests illustrating the validity of the method, and the factors affecting its accuracy. Finally we illustrate the effect of density matrix truncation on the optical response, and illustrate that computational load scales linearly with the system size.
MULTISCALE HOMOGENIZATION OF NONLINEAR HYPERBOLIC EQUATIONS WITH SEVERAL TIME SCALES
Jean Louis Woukeng; David Dongo
2011-01-01
We study the multiscale homogenization of a nonlinear hyperbolic equation in a periodic setting. We obtain an accurate homogenization result. We also show that as the nonlinear term depends on the microscopic time variable, the global homogenized problem thus obtained is a system consisting of two hyperbolic equations. It is also shown that in spite of the presence of several time scales, the global homogenized problem is not a reiterated one.
Improved jet noise modeling using a new acoustic time scale
Azarpeyvand, M.; Self, R.H.; Golliard, J.
2006-01-01
To calculate the noise emanating from a turbulent flow (such as a jet flow) using Lighthill's analogy, knowledge concerning the unsteady characteristics of the turbulence is required. Specifically, the form of the turbulent correlation tensor together with various time and length-scales and convecti
Quadratic Lyapunov Function and Exponential Dichotomy on Time Scales
ZHANG JI; LIU ZHEN-XIN
2011-01-01
In this paper, we study the relationship between exponential dichotomy and quadratic Lyapunov function for the linear equation x△ ＝ A(t)x on time scales.Moreover, for the nonlinear perturbed equation x△ ＝ A(t)x + f(t,x) we give the instability of the zero solution when f is sufficiently small.
Gott Time Machines, BTZ Black Hole Formation, and Choptuik Scaling
Birmingham, Daniel; Birmingham, Danny; Sen, Siddhartha
2000-01-01
We study the formation of BTZ black holes by the collision of point particles. It is shown that the Gott time machine, originally constructed for the case of vanishing cosmological constant, provides a precise mechanism for black hole formation. As a result, one obtains an exact analytic understanding of the Choptuik scaling.
Speech Compensation for Time-Scale-Modified Auditory Feedback
Ogane, Rintaro; Honda, Masaaki
2014-01-01
Purpose: The purpose of this study was to examine speech compensation in response to time-scale-modified auditory feedback during the transition of the semivowel for a target utterance of /ija/. Method: Each utterance session consisted of 10 control trials in the normal feedback condition followed by 20 perturbed trials in the modified auditory…
Wind power impacts and electricity storage - a time scale perspective
Hedegaard, Karsten; Meibom, Peter
2012-01-01
technologies – batteries, flow batteries, compressed air energy storage, electrolysis combined with fuel cells, and electric vehicles – are moreover categorised with respect to the time scales at which they are suited to support wind power integration. While all of these technologies are assessed suitable...
Gott time machines, BTZ black hole formation, and choptuik scaling
Birmingham; Sen
2000-02-07
We study the formation of Banados-Teitelboim-Zanelli black holes by the collision of point particles. It is shown that the Gott time machine, originally constructed for the case of vanishing cosmological constant, provides a precise mechanism for black hole formation. As a result, one obtains an exact analytic understanding of the Choptuik scaling.
Exponential stability of dynamic equations on time scales
Raffoul Youssef N
2005-01-01
Full Text Available We investigate the exponential stability of the zero solution to a system of dynamic equations on time scales. We do this by defining appropriate Lyapunov-type functions and then formulate certain inequalities on these functions. Several examples are given.
Identifying genes relevant to specific biological conditions in time course microarray experiments.
Singh, Nitesh Kumar; Repsilber, Dirk; Liebscher, Volkmar; Taher, Leila; Fuellen, Georg
2013-01-01
Microarrays have been useful in understanding various biological processes by allowing the simultaneous study of the expression of thousands of genes. However, the analysis of microarray data is a challenging task. One of the key problems in microarray analysis is the classification of unknown expression profiles. Specifically, the often large number of non-informative genes on the microarray adversely affects the performance and efficiency of classification algorithms. Furthermore, the skewed ratio of sample to variable poses a risk of overfitting. Thus, in this context, feature selection methods become crucial to select relevant genes and, hence, improve classification accuracy. In this study, we investigated feature selection methods based on gene expression profiles and protein interactions. We found that in our setup, the addition of protein interaction information did not contribute to any significant improvement of the classification results. Furthermore, we developed a novel feature selection method that relies exclusively on observed gene expression changes in microarray experiments, which we call "relative Signal-to-Noise ratio" (rSNR). More precisely, the rSNR ranks genes based on their specificity to an experimental condition, by comparing intrinsic variation, i.e. variation in gene expression within an experimental condition, with extrinsic variation, i.e. variation in gene expression across experimental conditions. Genes with low variation within an experimental condition of interest and high variation across experimental conditions are ranked higher, and help in improving classification accuracy. We compared different feature selection methods on two time-series microarray datasets and one static microarray dataset. We found that the rSNR performed generally better than the other methods.
Arbona, A.; Bona, C.; Miñano, B.; Plastino, A.
2014-09-01
The definition of complexity through Statistical Complexity Measures (SCM) has recently seen major improvements. Mostly, the effort is concentrated in measures on time series. We propose a SCM definition for spatial dynamical systems. Our definition is in line with the trend to combine entropy with measures of structure (such as disequilibrium). We study the behaviour of our definition against the vectorial noise model of Collective Motion. From a global perspective, we show how our SCM is minimal at both the microscale and macroscale, while it reaches a maximum at the ranges that define the mesoscale in this model. From a local perspective, the SCM is minimum both in highly ordered and disordered areas, while it reaches a maximum at the edges between such areas. These characteristics suggest this is a good candidate for detecting the mesoscale of arbitrary dynamical systems as well as regions where the complexity is maximal in such systems.
Tägil Magnus
2009-05-01
Full Text Available Abstract Background Rheumatic diseases commonly affect joints and other structures in the hand. Surgery is a traditional way to treat hand problems in inflammatory rheumatic diseases with the purposes of pain relief, restore function and prevent progression. There are numerous measures to choose from, and a combination of outcome measures is recommended. This study evaluated if instruments commonly used in rheumatologic clinical practice are suitable to measure outcome of hand surgery and to identify time points relevant for follow-up. Methods Thirty-one patients (median age 56 years, median disease duration 15 years with inflammatory rheumatic disease and need for post-surgical occupational therapy intervention formed this pilot study group. Hand function was assessed regarding grip strength (Grippit, pain (VAS, range of motion (ROM (Signals of Functional Impairment (SOFI and grip ability (Grip Ability Test (GAT. Activities of daily life (ADL were assessed by means of Disabilities of the Arm, Shoulder and Hand Outcome (DASH and Canadian Occupational Performance Measure (COPM. The instruments were evaluated by responsiveness and feasibility; follow-up points were 0, 3, 6 and 12 months. Results All instruments showed significant change at one or more follow-up points. Satisfaction with activities (COPM showed the best responsiveness (SMR>0.8, while ROM measured with SOFI had low responsiveness at most follow-up time points. The responsiveness of the instruments was stable between 6 and 12 month follow-up which imply that 6 month is an appropriate time for evaluating short-term effect of hand surgery in rheumatic diseases. Conclusion We suggest a core set of instruments measuring pain, grip strength, grip ability, perceived symptoms and self-defined daily activities. This study has shown that VAS pain, the Grippit instrument, GAT, DASH symptom scale and COPM are suitable outcome instruments for hand surgery, while SOFI may be a more insensitive
Human learning: Power laws or multiple characteristic time scales?
Gottfried Mayer-Kress
2006-09-01
Full Text Available The central proposal of A. Newell and Rosenbloom (1981 was that the power law is the ubiquitous law of learning. This proposition is discussed in the context of the key factors that led to the acceptance of the power law as the function of learning. We then outline the principles of an epigenetic landscape framework for considering the role of the characteristic time scales of learning and an approach to system identification of the processes of performance dynamics. In this view, the change of performance over time is the product of a superposition of characteristic exponential time scales that reflect the influence of different processes. This theoretical approach can reproduce the traditional power law of practice within the experimental resolution of performance data sets - but we hypothesize that this function may prove to be a special and perhaps idealized case of learning.
Real-time simulation of large-scale floods
Liu, Q.; Qin, Y.; Li, G. D.; Liu, Z.; Cheng, D. J.; Zhao, Y. H.
2016-08-01
According to the complex real-time water situation, the real-time simulation of large-scale floods is very important for flood prevention practice. Model robustness and running efficiency are two critical factors in successful real-time flood simulation. This paper proposed a robust, two-dimensional, shallow water model based on the unstructured Godunov- type finite volume method. A robust wet/dry front method is used to enhance the numerical stability. An adaptive method is proposed to improve the running efficiency. The proposed model is used for large-scale flood simulation on real topography. Results compared to those of MIKE21 show the strong performance of the proposed model.
Time Scales and Tidal Effects in Minor Mergers
Yu Lu; Jian-Yan Wei
2003-01-01
We use controlled N-body simulation to investigate the dynamical processes (dynamical friction, tidal truncation, etc.) involved in the merging of small satellites into bigger halos. We confirm the validity of some analytic formulae proposed earlier based on simple arguments. For rigid satellites represented by softened point masses, the merging time scale depends on both the orbital shape and concentration of the satellite. The dependence on orbital ellipticity is roughly a power law, as suggested by Lacey & Cole, and the dependence on satellite concentration is similar to that proposed by White. When merging satellites are represented by non-rigid objects, Tidal effects must be considered. We found that material beyond the tidal radius are stripped off. The decrease in the satellite mass might mean an increase in the merging time scale, but in fact, the merging time is decreased,because the stripped-off material carries away a proportionately larger amount of of orbital energy and angular momentum.
Cognitive componets of speech at different time scales
Feng, Ling; Hansen, Lars Kai
2007-01-01
Cognitive component analysis (COCA) is defined as unsupervised grouping of data leading to a group structure well aligned with that resulting from human cognitive activity. We focus here on speech at different time scales looking for possible hidden ‘cognitive structure’. Statistical regularities......, assumed to model the basic representation of the human auditory system. The basic features are aggregated in time to obtain features at longer time scales. Simple energy based filtering is used to achieve a sparse representation. Our hypothesis is now basically ecological: We hypothesize that features...... that are essentially independent in a reasonable ensemble can be efficiently coded using a sparse independent component representation. The representations are indeed shown to be very similar between supervised learning (invoking cognitive activity) and unsupervised learning (statistical regularities), hence lending...
Multiple time scale based reduction scheme for nonlinear chemical dynamics
Das, D.; Ray, D. S.
2013-07-01
A chemical reaction is often characterized by multiple time scales governing the kinetics of reactants, products and intermediates. We eliminate the fast relaxing intermediates in autocatalytic reaction by transforming the original system into a new one in which the linearized part is diagonal. This allows us to reduce the dynamical system by identifying the associated time scales and subsequent adiabatic elimination of the fast modes. It has been shown that the reduced system sustains the robust qualitative signatures of the original system and at times the generic form of the return map for the chaotic system from which complex dynamics stems out in the original system can be identified. We illustrate the scheme for a three-variable cubic autocatalytic reaction and four-variable peroxidase-oxidase reaction.
Nonlinear scale space with spatially varying stopping time.
Gilboa, Guy
2008-12-01
A general scale space algorithm is presented for denoising signals and images with spatially varying dominant scales. The process is formulated as a partial differential equation with spatially varying time. The proposed adaptivity is semi-local and is in conjunction with the classical gradient-based diffusion coefficient, designed to preserve edges. The new algorithm aims at maximizing a local SNR measure of the denoised image. It is based on a generalization of a global stopping time criterion presented recently by the author and colleagues. Most notably, the method works well also for partially textured images and outperforms any selection of a global stopping time. Given an estimate of the noise variance, the procedure is automatic and can be applied well to most natural images.
Terrestrial carbon-nitrogen interactions across time-scales
Zaehle, Sönke; Sickel, Kerstin
2017-04-01
Through its role in forming amino acids, nitrogen (N) plays a fundamental role in terrestrial biogeochemistry, affecting for instance the photosynthetic rate of a leaf, and the amount of leaf area of a plant; with further consequences for quasi instantaneous terrestrial biophysical properties and fluxes. Because of the high energy requirements of transforming atmospheric N2 to biologically available form, N is generally thought to be limiting terrestrial productivity. Experimental evidence and modelling studies suggest that in temperate and boreal ecosystems, this N-"limitation" affects plant production at scales from days to decades, and potentially beyond. Whether these interactions play a role at longer timescales, such as during the transition from the last glacial maximum to the holocene, is currently unclear. To address this question, we present results from a 22000 years long simulation with dynamic global vegetation model including a comprehensive treatment of the terrestrial carbon and nitrogen balance and their interactions (using the OCN-DGVM) driven by monthly, transient climate forcing obtained from the CESM climate model (TRACE). OCN couples carbon and nitrogen processes at the time-scale of hours, but simulates a comprehensive nitrogen balance as well as vegetation dynamics with time-scales of centuries and beyond. We investigate in particular, whether (and at with time scale) carbon-nitrogen interactions cause important lags in the response of the terrestrial biosphere to changed climate, and which processes (such as altered N inputs from fixation or altered losses through leaching and denitrification) contribute to these lags.
Energy and time determine scaling in biological and computer designs.
Moses, Melanie; Bezerra, George; Edwards, Benjamin; Brown, James; Forrest, Stephanie
2016-08-19
Metabolic rate in animals and power consumption in computers are analogous quantities that scale similarly with size. We analyse vascular systems of mammals and on-chip networks of microprocessors, where natural selection and human engineering, respectively, have produced systems that minimize both energy dissipation and delivery times. Using a simple network model that simultaneously minimizes energy and time, our analysis explains empirically observed trends in the scaling of metabolic rate in mammals and power consumption and performance in microprocessors across several orders of magnitude in size. Just as the evolutionary transitions from unicellular to multicellular animals in biology are associated with shifts in metabolic scaling, our model suggests that the scaling of power and performance will change as computer designs transition to decentralized multi-core and distributed cyber-physical systems. More generally, a single energy-time minimization principle may govern the design of many complex systems that process energy, materials and information.This article is part of the themed issue 'The major synthetic evolutionary transitions'.
Sherley, Richard B; Botha, Philna; Underhill, Les G; Ryan, Peter G; van Zyl, Danie; Cockcroft, Andrew C; Crawford, Robert J M; Dyer, Bruce M; Cook, Timothée R
2017-03-01
Human activities are important drivers of marine ecosystem functioning. However, separating the synergistic effects of fishing and environmental variability on the prey base of non-target predators is difficult, often because prey availability estimates on appropriate scales are lacking. Understanding how prey abundance at different spatial scales links to population change can help integrate the needs of non-target predators into fisheries management by defining ecologically-relevant areas for spatial protection. We investigated the local population response (number of breeders) of the bank cormorant Phalacrocorax neglectus, a range-restricted endangered seabird, to the availability of its prey, the heavily-fished west coast rock lobster Jasus lalandii. Using Bayesian state-space modeled cormorant counts at three colonies, 22 years of fisheries-independent data on local lobster abundance and generalized additive modeling, we determined the spatial-scale pertinent to these relationships in areas of differing lobster availability. Cormorant numbers responded positively to lobster availability in the intermediate and high abundance regions, but not where regime shifts and fishing pressure have depleted lobster stocks. The relationships were strongest at 20-30 km, greater than the cormorants' foraging range when breeding, and may have been influence by prey availability for non-breeding birds, prey switching or prey ecology. Our results highlight the importance of considering the scale of ecological relationships in marine spatial planning and suggest that designing spatial protection around focal species can benefit marine predators across their full life cycle. We propose the precautionary implementation of small-scale marine protected areas, followed by robust assessment and adaptive-management, to confirm population-level benefits for the cormorants, their prey and the wider ecosystem, without negative impacts on local fisheries. This article is protected by
An Extensible Timing Infrastructure for Adaptive Large-scale Applications
Stark, Dylan; Goodale, Tom; Radke, Thomas; Schnetter, Erik
2007-01-01
Real-time access to accurate and reliable timing information is necessary to profile scientific applications, and crucial as simulations become increasingly complex, adaptive, and large-scale. The Cactus Framework provides flexible and extensible capabilities for timing information through a well designed infrastructure and timing API. Applications built with Cactus automatically gain access to built-in timers, such as gettimeofday and getrusage, system-specific hardware clocks, and high-level interfaces such as PAPI. We describe the Cactus timer interface, its motivation, and its implementation. We then demonstrate how this timing information can be used by an example scientific application to profile itself, and to dynamically adapt itself to a changing environment at run time.
Anomalous multiphoton photoelectric effect in ultrashort time scales.
Kupersztych, J; Raynaud, M
2005-09-30
In a multiphoton photoelectric process, an electron needs to absorb a given number of photons to escape the surface of a metal. It is shown for the first time that this number is not a constant depending only on the characteristics of the metal and light, but varies with the interaction duration in ultrashort time scales. The phenomenon occurs when electromagnetic energy is transferred, via ultrafast excitation of electron collective modes, to conduction electrons in a duration less than the electron energy damping time. It manifests itself through a dramatic increase of electron production.
Multi-Scale Dissemination of Time Series Data
Guo, Qingsong; Zhou, Yongluan; Su, Li
2013-01-01
In this paper, we consider the problem of continuous dissemination of time series data, such as sensor measurements, to a large number of subscribers. These subscribers fall into multiple subscription levels, where each subscription level is specified by the bandwidth constraint of a subscriber......, which is an abstract indicator for both the physical limits and the amount of data that the subscriber would like to handle. To handle this problem, we propose a system framework for multi-scale time series data dissemination that employs a typical tree-based dissemination network and existing time-series...
The Available Time Scale: Measuring Foster Parents' Available Time to Foster
Cherry, Donna J.; Orme, John G.; Rhodes, Kathryn W.
2009-01-01
This article presents a new measure of available time specific to fostering, the Available Time Scale (ATS). It was tested with a national sample of 304 foster mothers and is designed to measure the amount of time foster parents are able to devote to fostering activities. The ATS has excellent reliability, and good support exists for its validity.…
QUALITATIVE BEHAVIORS OF LINEAR TIME-INVARIANT DYNAMIC EQUATIONS ON TIME SCALES
无
2010-01-01
We investigate the type of singularity and qualitative structure of solutions to a time-invariant linear dynamic system on time scales. The results truly unify the qualitative behaviors of the system on the continuous and discrete times with any step size.
Lecomte, Tania; Corbière, Marc; Laisné, François
2006-06-30
Studies investigating self-esteem in individuals with severe mental illness, either as a treatment goal, outcome or correlate to other variables, have increased over the past few years. One of the main difficulties in assessing self-esteem is the assessment itself, often measuring global and stable self-esteem as in the Rosenberg Self-Esteem Scale, or requiring extensive training and long interviews. The present article aims at demonstrating the relevance of the French and English versions of the Self-Esteem Rating Scale-Short Form with individuals with severe mental illness. The instrument's reliability and validity were investigated in a sample of 250 French Canadian college students, 247 British college students and three samples of English- or French-speaking individuals with severe mental illness (N=254, N=150 and N=171). Confirmatory factor analysis revealed that a shorter version of the instrument (20 items), with a positive and a negative self-esteem factor, had a great validity for all the samples studied. The Self-Esteem Rating Scale-Short Form, with its positive and negative self-esteem subscales, appears to be a valid and reliable self-esteem measure for individuals with mental health problems. Limitations of this study and future directions are discussed.
Miller, S.; Bankert, R.; Forsythe, J.; Mitrescu, C.; Reinke, D.; Austin, R.
2007-12-01
Clouds, representing perhaps the most obvious physical manifestations of atmospheric dynamics at work, remain in many ways an enigmatic and unifying intellectual challenge to researchers of all disciplines within the atmospheric sciences. Given the universally acknowledged importance of cloud systems in determining the state of current and future climate through radiative, chemical, dynamic, and thermodynamic processes tied intimately to the hydrological cycle, it is no wonder that so much recent attention has been given to better understanding the non-linear feedbacks involving clouds and ways to improve their handling in numerical weather prediction (NWP) models. In terms of operational community interests, knowledge of cloud vertical structure, ceiling (cloud base) height, and phase is key to aviation safety assurance in the private, commercial, and defense-agency sectors alike. The launch of the NASA Earth System Science Pathfinder CloudSat (cloud radar; 3 mm wavelength) mission in 2006 changed forever the way we view cloud systems from the space platform--providing vertically-resolved 'cuts' through the cloudy troposphere. The Cloud Profiling Radar (CPR) system resolves nearly all radiatively significant cloud structures present in the column at vertical resolutions sufficient to afford scientists the opportunity to examine new hypotheses on cloud formation (leading potentially to new/improved cloud process parameterizations) and make observationally-based discoveries bordering on the frontiers of our current understanding. At the same time, the non-scanning nature of the CPR (providing so-called 'curtain' observations) represents in some respects a frustrating tease to the potential of a three-dimensional scanning system, relegating its utility to the realms of research as opposed to full spatial environmental characterization and data assimilation. This research examines ways to extend via statistical methods the curtain slices provided by CloudSat into the
Time scale of diffusion in molecular and cellular biology
Holcman, D.; Schuss, Z.
2014-05-01
Diffusion is the driver of critical biological processes in cellular and molecular biology. The diverse temporal scales of cellular function are determined by vastly diverse spatial scales in most biophysical processes. The latter are due, among others, to small binding sites inside or on the cell membrane or to narrow passages between large cellular compartments. The great disparity in scales is at the root of the difficulty in quantifying cell function from molecular dynamics and from simulations. The coarse-grained time scale of cellular function is determined from molecular diffusion by the mean first passage time of molecular Brownian motion to a small targets or through narrow passages. The narrow escape theory (NET) concerns this issue. The NET is ubiquitous in molecular and cellular biology and is manifested, among others, in chemical reactions, in the calculation of the effective diffusion coefficient of receptors diffusing on a neuronal cell membrane strewn with obstacles, in the quantification of the early steps of viral trafficking, in the regulation of diffusion between the mother and daughter cells during cell division, and many other cases. Brownian trajectories can represent the motion of a molecule, a protein, an ion in solution, a receptor in a cell or on its membrane, and many other biochemical processes. The small target can represent a binding site or an ionic channel, a hidden active site embedded in a complex protein structure, a receptor for a neurotransmitter on the membrane of a neuron, and so on. The mean time to attach to a receptor or activator determines diffusion fluxes that are key regulators of cell function. This review describes physical models of various subcellular microdomains, in which the NET coarse-grains the molecular scale to a higher cellular-level, thus clarifying the role of cell geometry in determining subcellular function.
Time-Quality Tradeoff of Waiting Strategies for Tutors to Retrieve Relevant Teaching Methods
Shih, Wen-Chung; Tseng, Shian-Shyong; Yang, Che-Ching; Liang, Tyne
2011-01-01
As more and more undergraduate students act as voluntary tutors to rural pupils after school, there is a growing need for a supporting environment to facilitate adaptive instruction. Among others, a teaching method retrieval system is intended to help tutors find relevant teaching methods for teaching a particular concept. However, teaching…
Time-Quality Tradeoff of Waiting Strategies for Tutors to Retrieve Relevant Teaching Methods
Shih, Wen-Chung; Tseng, Shian-Shyong; Yang, Che-Ching; Liang, Tyne
2011-01-01
As more and more undergraduate students act as voluntary tutors to rural pupils after school, there is a growing need for a supporting environment to facilitate adaptive instruction. Among others, a teaching method retrieval system is intended to help tutors find relevant teaching methods for teaching a particular concept. However, teaching…
Time-sliced perturbation theory for large scale structure I: general formalism
Blas, Diego; Garny, Mathias; Ivanov, Mikhail M.; Sibiryakov, Sergey
2016-07-01
We present a new analytic approach to describe large scale structure formation in the mildly non-linear regime. The central object of the method is the time-dependent probability distribution function generating correlators of the cosmological observables at a given moment of time. Expanding the distribution function around the Gaussian weight we formulate a perturbative technique to calculate non-linear corrections to cosmological correlators, similar to the diagrammatic expansion in a three-dimensional Euclidean quantum field theory, with time playing the role of an external parameter. For the physically relevant case of cold dark matter in an Einstein-de Sitter universe, the time evolution of the distribution function can be found exactly and is encapsulated by a time-dependent coupling constant controlling the perturbative expansion. We show that all building blocks of the expansion are free from spurious infrared enhanced contributions that plague the standard cosmological perturbation theory. This paves the way towards the systematic resummation of infrared effects in large scale structure formation. We also argue that the approach proposed here provides a natural framework to account for the influence of short-scale dynamics on larger scales along the lines of effective field theory.
Realization of a time-scale with an optical clock
Grebing, C; Dörscher, S; Häfner, S; Gerginov, V; Weyers, S; Lipphardt, B; Riehle, F; Sterr, U; Lisdat, C
2015-01-01
Optical clocks are not only powerful tools for prime fundamental research, but are also deemed for the re-definition of the SI base unit second as they surpass the performance of caesium atomic clocks in both accuracy and stability by more than an order of magnitude. However, an important obstacle in this transition has so far been the limited reliability of the optical clocks that made a continuous realization of a time-scale impractical. In this paper, we demonstrate how this dilemma can be resolved and that a time-scale based on an optical clock can be established that is superior to one based on even the best caesium fountain clocks. The paper also gives further proof of the international consistency of strontium lattice clocks on the $10^{-16}$ accuracy level, which is another prerequisite for a change in the definition of the second.
Long-term variation time scales in OJ 287
Jun-Hui Fan; Yi Liu; Bo-Chun Qian; Jun Tao; Zhi-Qiang Shen; Jiang-Shui Zhang; Yong Huang; Jin Wang
2010-01-01
The light curve data from 1894 to 2008 are compiled for the BL Lacertae object OJ 287 from the available literature. Periodicity analysis methods (the Discrete Correlation Function-DCE the Jurkevich method, the power spectral (Fourier) analysis, and the CLEANest method) are performed to search for possible periodicites in the light curve of OJ 287. Significance levels are given for the possible periods. The analysis results confirm the existence of the 12.2 ± 0.6 yr time scale and show a hint of a～53 yr time scale. The 12.2 ± 0.6 yr period is used as the orbital period to investigate the supermassive binary black hole system parameters.
Seismic Interevent Time: A Spatial Scaling and Multifractality
Molchan, G
2005-01-01
The optimal scaling problem for the time t(LxL) between two successive events in a seismogenic cell of size L is considered. The quantity t(LxL) is defined for a random cell of a grid covering a seismic region G. We solve that problem in terms of a multifractal characteristic of epicenters in G known as the tau-function or generalized fractal dimensions; the solution depends on the type of cell randomization. Our theoretical deductions are corroborated by California seismicity with magnitude M>2. In other words, the population of waiting time distributions for L = 10-100 km provides positive information on the multifractal nature of seismicity, which impedes the population to be converted into a unified law by scaling. This study is a follow-up of our analysis of power/unified laws for seismicity (see PAGEOPH 162 (2005), 1135 and GJI 162 (2005), 899).
Oligocene calibration of the magnetic polarity time scale
Prothero, Donald R.; Denham, Charles R.; Farmer, Harlow G.
1982-12-01
Magnetostratigraphic studies of the Oligocene White River Group in Wyoming, Colorado, Nebraska, and the Dakotas yield a radiometrically dated polarity stratigraphy that provides mid-Tertiary calibration points for the magnetic polarity time scale. Anomaly 12 13 reversal is bracketed by dates of 32.4 and 34.6 m.y., in best agreement with the time scale of LaBrecque and colleagues. The magnetostratigraphy also helps calibrate the Oligocene North American land mammal “ages” and allows correlation with the European marine microfossil zonation. This correlation suggests that the age of the Eocene-Oligocene boundary is 37.0 m.y., contrary to younger dates obtained from glauconites and microtektites. *Present address: Department of Geology, Knox College, Galesburg, Illinois 61401
HMC algorithm with multiple time scale integration and mass preconditioning
Urbach, C; Shindler, A; Wenger, U
2006-01-01
We present a variant of the HMC algorithm with mass preconditioning (Hasenbusch acceleration) and multiple time scale integration. We have tested this variant for standard Wilson fermions at beta=5.6 and at pion masses ranging from 380 MeV to 680 MeV. We show that in this situation its performance is comparable to the recently proposed HMC variant with domain decomposition as preconditioner. We give an update of the ``Berlin Wall'' figure, comparing the performance of our variant of the HMC algorithm to other published performance data. Advantages of the HMC algorithm with mass preconditioning and multiple time scale integration are that it is straightforward to implement and can be used in combination with a wide variety of lattice Dirac operators.
HMC algorithm with multiple time scale integration and mass preconditioning
Urbach, C.; Jansen, K.; Shindler, A.; Wenger, U.
2006-01-01
We present a variant of the HMC algorithm with mass preconditioning (Hasenbusch acceleration) and multiple time scale integration. We have tested this variant for standard Wilson fermions at β=5.6 and at pion masses ranging from 380 to 680 MeV. We show that in this situation its performance is comparable to the recently proposed HMC variant with domain decomposition as preconditioner. We give an update of the "Berlin Wall" figure, comparing the performance of our variant of the HMC algorithm to other published performance data. Advantages of the HMC algorithm with mass preconditioning and multiple time scale integration are that it is straightforward to implement and can be used in combination with a wide variety of lattice Dirac operators.
Entropy Production of Nanosystems with Time Scale Separation
Wang, Shou-Wen; Kawaguchi, Kyogo; Sasa, Shin-ichi; Tang, Lei-Han
2016-08-01
Energy flows in biomolecular motors and machines are vital to their function. Yet experimental observations are often limited to a small subset of variables that participate in energy transport and dissipation. Here we show, through a solvable Langevin model, that the seemingly hidden entropy production is measurable through the violation spectrum of the fluctuation-response relation of a slow observable. For general Markov systems with time scale separation, we prove that the violation spectrum exhibits a characteristic plateau in the intermediate frequency region. Despite its vanishing height, the plateau can account for energy dissipation over a broad time scale. Our findings suggest a general possibility to probe hidden entropy production in nanosystems without direct observation of fast variables.
Algorithm of simulation time synchronization over large-scale nodes
ZHAO QinPing; ZHOU Zhong; Lü Fang
2008-01-01
In distributed simulation, there is no uniform physical clock. And delay cannot be estimated because of jitter. So simulation time synchronization is essential for the event consistency among nodes. This paper investigates time synchronization algorithms over large-scale distributed nodes, analyzes LBTS (lower bound time stamp) computation model described in IEEE HLA standard, and then presents a grouped LBTS model. In fact, there is a default premise for existing algorithms that control packets must be delivered via reliable transportation. Although, a theorem of time synchronization message's reliability is proposed, which proves that only those control messages that constrain time advance need reliability. It breaks out the default premise for reliability. Then multicast is introduced into the transmission of control messages, and algorithm MCTS (multi-node coordination time synchronization) is proposed based on multicast. MCTS not only promotes the time advance efficiency, but also reduces the occupied network bandwidth. Experiment results demonstrate that the algorithm is better than others in both time advance speed and occupied network bandwidth. Its time advance speed is about 50 times per second when there are 1000 nodes, approximately equal to that of similar systems when there are 100 nodes.
The fission time scale measured with an atomic clock
Kravchuk, VL; Wilschut, HW; Hunyadi, M; Kopecky, S; Lohner, H; Rogachevskiy, A; Siemssen, RH; Krasznahorkay, A; Hamilton, JH; Ramayya, AV; Carter, HK
2003-01-01
We present a new direct method of measuring the fission absolute time scale using an atomic clock based on the lifetime of a vacancy in the atomic K-shell. We studied the reaction Ne-20 + Th-232 -> O-16 + U-236* at 30 MeV/u. The excitation energy of about 115 MeV in such a reaction is in the range w
Isoperimetric problems on time scales with nabla derivatives
Almeida, Ricardo; Torres, Delfim F. M.
2008-01-01
We prove a necessary optimality condition for isoperimetric problems under nabla-differentiable curves. As a consequence, the recent results of [M.R. Caputo, A unified view of ostensibly disparate isoperimetric variational problems, Appl. Math. Lett. (2008), doi:10.1016/j.aml.2008.04.004], that put together seemingly dissimilar optimal control problems in economics and physics, are extended to a generic time scale. We end with an illustrative example of application of our main result to a dyn...
The distribution of length scales generated by mixing processes in time-p eriodic chaotic flows
Muzzio, Fernando; Alvarez, Mario; Cerbelli, Stefano
1997-11-01
This talk explores in some detail the evolution of the spatial structure and th e statistical properties of partially mixed systems as they evolve on a torus by using a direct numerical simulation of the evolution of continuous material lin es as they are stretched, reoriented, and folded by the flow. In the time scale s of interest to mixing processes, such material lines grow exponentially fast, but much faster than predicted by the Lyapunov exponent. The filament develops into a self-similar structure; frequency distribution of filament densities corr esponding to different times collapses onto an invariant curve by a simple homog eneous scaling. It is shown that this behavior is a direct consequence of a gen eric asymptotic directionality property characteristic of 2D time-periodic flows . Mixture microstructure is also analyzed by computing the evolution of th e distribution of length scales in the flow. Once again, the result is a family of self-similar curves that scale homogeneously by the mean length scale, which collapses in inverse proportion to the rate of growth of the filament. It is s hown that this rate of collapse, which has direct relevance to mixing applicatio ns, can be accurately and straightforwardly predicted from the ergodic average o f the stretching field. Implications for mixing processes in realistic systems are also discussed.
Time scale interactions and the coevolution of humans and water
Sivapalan, Murugesu; Blöschl, Günter
2015-09-01
We present a coevolutionary view of hydrologic systems, revolving around feedbacks between environmental and social processes operating across different time scales. This brings to the fore an emphasis on emergent phenomena in changing water systems, such as the levee effect, adaptation to change, system lock-in, and system collapse due to resource depletion. Changing human values play a key role in the emergence of these phenomena and should therefore be considered as internal to the system. Guidance is provided for the framing and modeling of these phenomena to test alternative hypotheses about how they arose. A plurality of coevolutionary models, from stylized to comprehensive system-of-system models, may assist strategic water management for long time scales through facilitating stakeholder participation, exploring the possibility space of alternative futures, and helping to synthesize the observed dynamics in a wide range of case studies. Future research opportunities lie in exploring emergent phenomena arising from time scale interactions through historical, comparative, and process studies of human-water feedbacks.
A stable Cenozoic geologic time scale is indispensable
Amos Salvador
2006-01-01
@@ A stable, standard geologic time scale is indispensable for the clear and precise communication among geologists; it is a basic tool of geologic work. Considerable progress has been made to achieve such a stable time scale. However, during the last few years several proposals have been made to modify the Cenozoic section of the geologic time scale that threaten to destabilize it.Seven articles published in Episodes since 2000 that could contribute to this destabilization are discussed.They provide excellent examples of the profusion of different terminologies, hierarchies, and stratigraphic relationships that have been proposed: to eliminate the Tertiary and the Quaternary or to raise their rank to suberathems; to extend the Neogene to the present; to make the Quaternary a formal subsystem of the Neogene, or consider it an informal stratigraphic unit; to eliminate the Holocene, and to decouple the base of the Pleistocene from the base of the Quaternary. If adopted,these proposals would cause nothing but great confusion and controversy. They disregard the clear preferences of geologists the world over as reflected by the terminology they have been using for many decades. Common sense would dictate the continued use of this terminology in its current, widely accepted form.
Saker, Odie
2008-01-01
Objectives: The aim of this study was: (1) To determine the relevant processing times for clinical practice. (2) To analyze the flow properties of several elastomeric impression materials depending on these clinically measured times by means of the modified sharkfin test. Methods and materials: (1) Clinical trial: The processing times of 86 clinical cases were measured by the same person. The impressions were taken by 14 different clinicians with the one-step technique (Impregum-Penta as...
Evidence for two time scales in long SNS junctions.
Chiodi, F; Aprili, M; Reulet, B
2009-10-23
We use microwave excitation to elucidate the dynamics of long superconductor-normal metal-superconductor Josephson junctions. By varying the excitation frequency in the range 10 MHz-40 GHz, we observe that the critical and retrapping currents, deduced from the dc voltage versus dc current characteristics of the junction, are set by two different time scales. The critical current increases when the ac frequency is larger than the inverse diffusion time in the normal metal, whereas the retrapping current is strongly modified when the excitation frequency is above the electron-phonon rate in the normal metal. Therefore the critical and retrapping currents are associated with elastic and inelastic scattering, respectively.
Fine Scale Baleen Whale Behavior Observed Via Tagging Over Daily Time Scales
2015-09-30
cetacean behavior at intermediate daily time scales. Recent efforts to assess the impacts of sound on marine mammals and to estimate foraging...new dermal attachment for short-term tagging studies of baleen whales. Methods in Ecology and Evolution 6:289-297. Baumgartner, M.F., N.S.J
Scale and time dependence of serial correlations in word-length time series of written texts
Rodriguez, E.; Aguilar-Cornejo, M.; Femat, R.; Alvarez-Ramirez, J.
2014-11-01
This work considered the quantitative analysis of large written texts. To this end, the text was converted into a time series by taking the sequence of word lengths. The detrended fluctuation analysis (DFA) was used for characterizing long-range serial correlations of the time series. To this end, the DFA was implemented within a rolling window framework for estimating the variations of correlations, quantified in terms of the scaling exponent, strength along the text. Also, a filtering derivative was used to compute the dependence of the scaling exponent relative to the scale. The analysis was applied to three famous English-written literary narrations; namely, Alice in Wonderland (by Lewis Carrol), Dracula (by Bram Stoker) and Sense and Sensibility (by Jane Austen). The results showed that high correlations appear for scales of about 50-200 words, suggesting that at these scales the text contains the stronger coherence. The scaling exponent was not constant along the text, showing important variations with apparent cyclical behavior. An interesting coincidence between the scaling exponent variations and changes in narrative units (e.g., chapters) was found. This suggests that the scaling exponent obtained from the DFA is able to detect changes in narration structure as expressed by the usage of words of different lengths.
Two-time-scale population evolution on a singular landscape
Xu, Song; Jiao, Shuyun; Jiang, Pengyao; Ao, Ping
2014-01-01
Under the effect of strong genetic drift, it is highly probable to observe gene fixation or gene loss in a population, shown by singular peaks on a potential landscape. The genetic drift-induced noise gives rise to two-time-scale diffusion dynamics on the bipeaked landscape. We find that the logarithmically divergent (singular) peaks do not necessarily imply infinite escape times or biological fixations by iterating the Wright-Fisher model and approximating the average escape time. Our analytical results under weak mutation and weak selection extend Kramers's escape time formula to models with B (Beta) function-like equilibrium distributions and overcome constraints in previous methods. The constructed landscape provides a coherent description for the bistable system, supports the quantitative analysis of bipeaked dynamics, and generates mathematical insights for understanding the boundary behaviors of the diffusion model.
Stability theory for dynamic equations on time scales
Martynyuk, Anatoly A
2016-01-01
This monograph is a first in the world to present three approaches for stability analysis of solutions of dynamic equations. The first approach is based on the application of dynamic integral inequalities and the fundamental matrix of solutions of linear approximation of dynamic equations. The second is based on the generalization of the direct Lyapunovs method for equations on time scales, using scalar, vector and matrix-valued auxiliary functions. The third approach is the application of auxiliary functions (scalar, vector, or matrix-valued ones) in combination with differential dynamic inequalities. This is an alternative comparison method, developed for time continuous and time discrete systems. In recent decades, automatic control theory in the study of air- and spacecraft dynamics and in other areas of modern applied mathematics has encountered problems in the analysis of the behavior of solutions of time continuous-discrete linear and/or nonlinear equations of perturbed motion. In the book “Men of Ma...
Time-Sliced Perturbation Theory for Large Scale Structure I: General Formalism
Blas, Diego; Ivanov, Mikhail M; Sibiryakov, Sergey
2016-01-01
We present a new analytic approach to describe large scale structure formation in the mildly non-linear regime. The central object of the method is the time-dependent probability distribution function generating correlators of the cosmological observables at a given moment of time. Expanding the distribution function around the Gaussian weight we formulate a perturbative technique to calculate non-linear corrections to cosmological correlators, similar to the diagrammatic expansion in a three-dimensional Euclidean quantum field theory, with time playing the role of an external parameter. For the physically relevant case of cold dark matter in an Einstein--de Sitter universe, the time evolution of the distribution function can be found exactly and is encapsulated by a time-dependent coupling constant controlling the perturbative expansion. We show that all building blocks of the expansion are free from spurious infrared enhanced contributions that plague the standard cosmological perturbation theory. This pave...
Scaling in non-stationary time series. (I)
Ignaccolo, M.; Allegrini, P.; Grigolini, P.; Hamilton, P.; West, B. J.
2004-05-01
Most data processing techniques, applied to biomedical and sociological time series, are only valid for random fluctuations that are stationary in time. Unfortunately, these data are often non-stationary and the use of techniques of analysis resting on the stationary assumption can produce a wrong information on the scaling, and so on the complexity of the process under study. Herein, we test and compare two techniques for removing the non-stationary influences from computer generated time series, consisting of the superposition of a slow signal and a random fluctuation. The former is based on the method of wavelet decomposition, and the latter is a proposal of this paper, denoted by us as step detrending technique. We focus our attention on two cases, when the slow signal is a periodic function mimicking the influence of seasons, and when it is an aperiodic signal mimicking the influence of a population change (increase or decrease). For the purpose of computational simplicity the random fluctuation is taken to be uncorrelated. However, the detrending techniques here illustrated work also in the case when the random component is correlated. This expectation is fully confirmed by the sociological applications made in the companion paper. We also illustrate a new procedure to assess the existence of a genuine scaling, based on the adoption of diffusion entropy, multiscaling analysis and the direct assessment of scaling. Using artificial sequences, we show that the joint use of all these techniques yield the detection of the real scaling, and that this is independent of the technique used to detrend the original signal.
Multiple time scale behaviors and network dynamics in liquid methanol.
Sharma, Ruchi; Chakravarty, Charusita; Milotti, Edoardo
2008-07-31
Canonical ensemble molecular dynamics simulations of liquid methanol, modeled using a rigid-body, pair-additive potential, are used to compute static distributions and temporal correlations of tagged molecule potential energies as a means of characterizing the liquid state dynamics. The static distribution of tagged molecule potential energies shows a clear multimodal structure with three distinct peaks, similar to those observed previously in water and liquid silica. The multimodality is shown to originate from electrostatic effects, but not from local, hydrogen bond interactions. An interesting outcome of this study is the remarkable similarity in the tagged potential energy power spectra of methanol, water, and silica, despite the differences in the underlying interactions and the dimensionality of the network. All three liquids show a distinct multiple time scale (MTS) regime with a 1/ f (alpha) dependence with a clear positive correlation between the scaling exponent alpha and the diffusivity. The low-frequency limit of the MTS regime is determined by the frequency of crossover to white noise behavior which occurs at approximately 0.1 cm (-1) in the case of methanol under standard temperature and pressure conditions. The power spectral regime above 200 cm (-1) in all three systems is dominated by resonances due to localized vibrations, such as librations. The correlation between alpha and the diffusivity in all three liquids appears to be related to the strength of the coupling between the localized motions and the larger length/time scale network reorganizations. Thus, the time scales associated with network reorganization dynamics appear to be qualitatively similar in these systems, despite the fact that water and silica both display diffusional anomalies but methanol does not.
Hamido, Aliou; Madroñero, Javier; Mota-Furtado, Francisca; O'Mahony, Patrick; Frapiccini, Ana Laura; Piraux, Bernard
2011-01-01
We present an ab initio approach to solve the time-dependent Schr\\"odinger equation to treat electron and photon impact multiple ionization of atoms or molecules. It combines the already known time scaled coordinate method with a new high order time propagator based on a predictor-corrector scheme. In order to exploit in an optimal way the main advantage of the time scaled coordinate method namely that the scaled wave packet stays confined and evolves smoothly towards a stationary state the modulus square of which being directly proportional to the electron energy spectra in each ionization channel, we show that the scaled bound states should be subtracted from the total scaled wave packet. In addition, our detailed investigations suggest that multi-resolution techniques like for instance, wavelets are the most appropriate ones to represent spatially the scaled wave packet. The approach is illustrated in the case of the interaction of an one-dimensional model atom as well as atomic hydrogen with a strong osci...
On the magnetic field evolution time-scale in superconducting neutron star cores
Passamonti, Andrea; Akgün, Taner; Pons, José A.; Miralles, Juan A.
2017-08-01
We revisit the various approximations employed to study the long-term evolution of the magnetic field in neutron star cores and discuss their limitations and possible improvements. A recent controversy on the correct form of the induction equation and the relevant evolution time-scale in superconducting neutron star cores is addressed and clarified. We show that this ambiguity in the estimation of time-scales arises as a consequence of nominally large terms that appear in the induction equation, but which are, in fact, mostly irrotational. This subtlety leads to a discrepancy by many orders of magnitude when velocity fields are absent or ignored. Even when internal velocity fields are accounted for, only the solenoidal part of the electric field contributes to the induction equation, which can be substantially smaller than the irrotational part. We also argue that stationary velocity fields must be incorporated in the slow evolution of the magnetic field as the next level of approximation.
Time scale hierarchies in the functional organization of complex behaviors.
Dionysios Perdikis
2011-09-01
Full Text Available Traditional approaches to cognitive modelling generally portray cognitive events in terms of 'discrete' states (point attractor dynamics rather than in terms of processes, thereby neglecting the time structure of cognition. In contrast, more recent approaches explicitly address this temporal dimension, but typically provide no entry points into cognitive categorization of events and experiences. With the aim to incorporate both these aspects, we propose a framework for functional architectures. Our approach is grounded in the notion that arbitrary complex (human behaviour is decomposable into functional modes (elementary units, which we conceptualize as low-dimensional dynamical objects (structured flows on manifolds. The ensemble of modes at an agent's disposal constitutes his/her functional repertoire. The modes may be subjected to additional dynamics (termed operational signals, in particular, instantaneous inputs, and a mechanism that sequentially selects a mode so that it temporarily dominates the functional dynamics. The inputs and selection mechanisms act on faster and slower time scales then that inherent to the modes, respectively. The dynamics across the three time scales are coupled via feedback, rendering the entire architecture autonomous. We illustrate the functional architecture in the context of serial behaviour, namely cursive handwriting. Subsequently, we investigate the possibility of recovering the contributions of functional modes and operational signals from the output, which appears to be possible only when examining the output phase flow (i.e., not from trajectories in phase space or time.
The Role of Time-Scales in Socio-hydrology
Blöschl, Günter; Sivapalan, Murugesu
2016-04-01
Much of the interest in hydrological modeling in the past decades revolved around resolving spatial variability. With the rapid changes brought about by human impacts on the hydrologic cycle, there is now an increasing need to refocus on time dependency. We present a co-evolutionary view of hydrologic systems, in which every part of the system including human systems, co-evolve, albeit at different rates. The resulting coupled human-nature system is framed as a dynamical system, characterized by interactions of fast and slow time scales and feedbacks between environmental and social processes. This gives rise to emergent phenomena such as the levee effect, adaptation to change and system collapse due to resource depletion. Changing human values play a key role in the emergence of these phenomena and should therefore be considered as internal to the system in a dynamic way. The co-evolutionary approach differs from the traditional view of water resource systems analysis as it allows for path dependence, multiple equilibria, lock-in situations and emergent phenomena. The approach may assist strategic water management for long time scales through facilitating stakeholder participation, exploring the possibility space of alternative futures, and helping to synthesise the observed dynamics of different case studies. Future research opportunities include the study of how changes in human values are connected to human-water interactions, historical analyses of trajectories of system co-evolution in individual places and comparative analyses of contrasting human-water systems in different climate and socio-economic settings. Reference Sivapalan, M. and G. Blöschl (2015) Time scale interactions and the coevolution of humans and water. Water Resour. Res., 51, 6988-7022, doi:10.1002/2015WR017896.
Terrestrial Waters and Sea Level Variations on Interannual Time Scale
Llovel, W.; Becker, M.; Cazenave, A.; Jevrejeva, S.; Alkama, R.; Decharme, B.; Douville, H.; Ablain, M.; Beckley, B.
2011-01-01
On decadal to multi-decadal time scales, thermal expansion of sea waters and land ice loss are the main contributors to sea level variations. However, modification of the terrestrial water cycle due to climate variability and direct anthropogenic forcing may also affect sea level. For the past decades, variations in land water storage and corresponding effects on sea level cannot be directly estimated from observations because these are almost non-existent at global continental scale. However, global hydrological models developed for atmospheric and climatic studies can be used for estimating total water storage. For the recent years (since mid-2002), terrestrial water storage change can be directly estimated from observations of the GRACE space gravimetry mission. In this study, we analyse the interannual variability of total land water storage, and investigate its contribution to mean sea level variability at interannual time scale. We consider three different periods that, each, depend on data availability: (1) GRACE era (2003-2009), (2) 1993-2003 and (3) 1955-1995. For the GRACE era (period 1), change in land water storage is estimated using different GRACE products over the 33 largest river basins worldwide. For periods 2 and 3, we use outputs from the ISBA-TRIP (Interactions between Soil, Biosphere, and Atmosphere-Total Runoff Integrating Pathways) global hydrological model. For each time span, we compare change in land water storage (expressed in sea level equivalent) to observed mean sea level, either from satellite altimetry (periods 1 and 2) or tide gauge records (period 3). For each data set and each time span, a trend has been removed as we focus on the interannual variability. We show that whatever the period considered, interannual variability of the mean sea level is essentially explained by interannual fluctuations in land water storage, with the largest contributions arising from tropical river basins.
Demeere, Nathalie; Stouthuysen, Kristof; Roodhooft, Filip
2009-10-01
Healthcare managers are continuously urged to provide better patient services at a lower cost. To cope with these cost pressures, healthcare management needs to improve its understanding of the relevant cost drivers. Through a case study, we show how to perform a time-driven activity-based costing of five outpatient clinic's departments and provide evidence of the benefits of such an analysis.
Holographic Brownian motion and time scales in strongly coupled plasmas
Atmaja, Ardian Nata [Research Center for Physics, Indonesian Institute of Sciences (LIPI), Kompleks PUSPITEK Serpong, Tangerang 15310 (Indonesia); Indonesia Center for Theoretical and Mathematical Physics (ICTMP), Bandung 40132 (Indonesia); Boer, Jan de [Institute for Theoretical Physics, University of Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands); Shigemori, Masaki [Yukawa Institute for Theoretical Physics (YITP), Kyoto University, Kitashirakawa Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Hakubi Center, Kyoto University, Yoshida-Ushinomiyacho, Sakyo-ku, Kyoto 606-8501 (Japan)
2014-03-15
We study Brownian motion of a heavy quark in field theory plasma in the AdS/CFT setup and discuss the time scales characterizing the interaction between the Brownian particle and plasma constituents. Based on a simple kinetic theory, we first argue that the mean-free-path time is related to the connected 4-point function of the random force felt by the Brownian particle. Then, by holographically computing the 4-point function and regularizing the IR divergence appearing in the computation, we write down a general formula for the mean-free-path time, and apply it to the STU black hole which corresponds to plasma charged under three U(1)R-charges. The result indicates that the Brownian particle collides with many plasma constituents simultaneously.
Stochastic models for structured populations scaling limits and long time behavior
Meleard, Sylvie
2015-01-01
In this contribution, several probabilistic tools to study population dynamics are developed. The focus is on scaling limits of qualitatively different stochastic individual based models and the long time behavior of some classes of limiting processes. Structured population dynamics are modeled by measure-valued processes describing the individual behaviors and taking into account the demographic and mutational parameters, and possible interactions between individuals. Many quantitative parameters appear in these models and several relevant normalizations are considered, leading to infinite-dimensional deterministic or stochastic large-population approximations. Biologically relevant questions are considered, such as extinction criteria, the effect of large birth events, the impact of environmental catastrophes, the mutation-selection trade-off, recovery criteria in parasite infections, genealogical properties of a sample of individuals. These notes originated from a lecture series on Structured P...
The role of time scales in extrinsic noise propagation
Iyer-Biswas, Srividya; Pedraza, Juan Manuel; Jayaprakash, C.
2009-03-01
Cell-to cell variability in the number of proteins has been studied extensively experimentally. There are many sources of this stochastic variability or noise that can be classified as intrinsic, due to the stochasticity of chemical reactions and extrinsic, due to environmental differences. The different stages in the production of proteins in response to a stimulus, the signaling cascade before transcription, transcription, and translation are characterized by different time scales. We analyze how these time scales determine the effect of the reactions at each stage on different sources of noise. For example, even if intrinsic noise dominates the fluctuations in mRNA number, for typical degradation rates, extrinsic noise can dominate corresponding protein number fluctuations. Such results are important in determining the importance of intrinsic noise at earlier stages of a genetic network on the products of subsequent stages. We examine cases in which the dynamics of the extrinsic noise can lead to differences from cases in which extrinsic noise arises from static (in time) cell-to-cell variations. We will interpret the experiments of Pedraza et al*. in the light of these results. *J. M. Pedraza et al, Science 25 March 2005:Vol. 307. no. 5717, pp. 1965 - 1969.
The application of models to find the relevance of residence time in lake and reservoir management
Sven E. JØRGENSEN
2003-09-01
Full Text Available The residence time is among the most important factors that determine the water quality of lakes and reservoirs. Models are useful tools to reveal the relationship between the residence time and the water quality. Three case studies are presented to illustrate the application of models to determine the importance of the residence time for the water quality. It was found that manipulation of the residence time, i.e. ecohydrology, may be a very useful environmental management tool.
A Multiscale Lattice-Boltzmann Model of Macro-to-Micro Scale Transport Relevant to Gut Function
Wang, Yanxing; Brasseur, James; Banco, Gino
2007-11-01
Nutrient and pharmaceutical absorption in the small intestine involve coupled multiscale transport and mixing processes that span several orders of magnitude. We hypothesize that muscle-induced villi motions generate and control a ``micro-mixing layer'' that couples with macro-scale mixing to enhance molecular transport to and from the epithelium. In this work we developed a 2-D numerical method based on a multigrid strategy within the lattice-Boltzmann framework. We model a macro-scale cavity flow with microscale finger-like villi in pendular motion on the lower surface and evaluate the coupling between macro and micro-scale fluid motions, scalar mixing, and uptake of passive scalar at the villi surface. Preliminary results show that the moving villi can be effective mixers at the micro scale, especially when groups of villi move in a coordinated, but out-of-phase fashion. A time-evolving series of flow recirculation eddies are generated within a micro mixing layer that increase transport of passive scalar from the macro eddy to the surface by advection. Flow parameters such as frequency of pendular motion, spacing between villi and villi grouping, have strong influences on the behaviors of the micro-mixing layer and the efficiency of scalar transport. An extensive analysis is in process to quantify correlation between scalar mixing and flux, details of villi motion, and induced flow patterns.
Formation processes and time scales for meteorite parent bodies
Weidenschilling, S. J.
1988-01-01
The transition from small particles suspended in the solar nebula to the planetesimals (asteroids) that became the parent bodies of meteorites is examined. Planetesimals probably grew by coagulation of grain aggregates that collided due to different rates of settling and drag-induced orbital decay. Their growth was accompanied by radial transport of solids, possibly sufficient to deplete the primordial mass in the asteroid zone, but with relatively little mixing. The formation of asteroid-sized planetesimals was probably rapid, on a time scale less than 1 Myr.
Time-Dependent Earthquake Forecasts on a Global Scale
Rundle, J. B.; Holliday, J. R.; Turcotte, D. L.; Graves, W. R.
2014-12-01
We develop and implement a new type of global earthquake forecast. Our forecast is a perturbation on a smoothed seismicity (Relative Intensity) spatial forecast combined with a temporal time-averaged ("Poisson") forecast. A variety of statistical and fault-system models have been discussed for use in computing forecast probabilities. An example is the Working Group on California Earthquake Probabilities, which has been using fault-based models to compute conditional probabilities in California since 1988. An example of a forecast is the Epidemic-Type Aftershock Sequence (ETAS), which is based on the Gutenberg-Richter (GR) magnitude-frequency law, the Omori aftershock law, and Poisson statistics. The method discussed in this talk is based on the observation that GR statistics characterize seismicity for all space and time. Small magnitude event counts (quake counts) are used as "markers" for the approach of large events. More specifically, if the GR b-value = 1, then for every 1000 M>3 earthquakes, one expects 1 M>6 earthquake. So if ~1000 M>3 events have occurred in a spatial region since the last M>6 earthquake, another M>6 earthquake should be expected soon. In physics, event count models have been called natural time models, since counts of small events represent a physical or natural time scale characterizing the system dynamics. In a previous research, we used conditional Weibull statistics to convert event counts into a temporal probability for a given fixed region. In the present paper, we move belyond a fixed region, and develop a method to compute these Natural Time Weibull (NTW) forecasts on a global scale, using an internally consistent method, in regions of arbitrary shape and size. We develop and implement these methods on a modern web-service computing platform, which can be found at www.openhazards.com and www.quakesim.org. We also discuss constraints on the User Interface (UI) that follow from practical considerations of site usability.
Jørgensen, Peter Søgaard; Böhning-Gaese, Katrin; Thorup, Kasper;
2016-01-01
Species attributes are commonly used to infer impacts of environmental change on multiyear species trends, e.g. decadal changes in population size. However, by themselves attributes are of limited value in global change attribution since they do not measure the changing environment. A broader...... foundation for attributing species responses to global change may be achieved by complementing an attributes-based approach by one estimating the relationship between repeated measures of organismal and environmental changes over short time scales. To assess the benefit of this multiscale perspective, we...... on or in the peak of the breeding season with the largest effect sizes observed in cooler parts of species' climatic ranges. Our results document the potential of combining time scales and integrating both species attributes and environmental variables for global change attribution. We suggest such an approach...
A biologically plausible model of time-scale invariant interval timing.
Almeida, Rita; Ledberg, Anders
2010-02-01
The temporal durations between events often exert a strong influence over behavior. The details of this influence have been extensively characterized in behavioral experiments in different animal species. A remarkable feature of the data collected in these experiments is that they are often time-scale invariant. This means that response measurements obtained under intervals of different durations coincide when plotted as functions of relative time. Here we describe a biologically plausible model of an interval timing device and show that it is consistent with time-scale invariant behavior over a substantial range of interval durations. The model consists of a set of bistable units that switch from one state to the other at random times. We first use an abstract formulation of the model to derive exact expressions for some key quantities and to demonstrate time-scale invariance for any range of interval durations. We then show how the model could be implemented in the nervous system through a generic and biologically plausible mechanism. In particular, we show that any system that can display noise-driven transitions from one stable state to another can be used to implement the timing device. Our work demonstrates that a biologically plausible model can qualitatively account for a large body of data and thus provides a link between the biology and behavior of interval timing.
Residential Mobility and Turnout: The Relevance of Social Costs, Timing and Education
Hansen, Jonas Hedegaard
2016-01-01
Residential mobility has substantial negative effects on voter turnout. However, existing studies have been unable to disentangle whether this is due to social costs, informational costs or convenience costs that are related to re-registration. This article analyzes the relevance of the different...... settling down. This illustrates that large events in citizens’ everyday life close to Election Day can distract them from going to the polling station. Finally, residential mobility mostly affects the turnout of less educated citizens. Consequentially, residential mobility increases inequalities in voter...... costs by studying the effect of moving and reassignment to a new polling station in an automatic registration context and using a register-based panel dataset with validated turnout for 2.1 million citizens. The negative effect of moving on turnout does not differ substantially depending on the distance...
A Review of Time-Scale Modification of Music Signals
Jonathan Driedger
2016-02-01
Full Text Available Time-scale modification (TSM is the task of speeding up or slowing down an audio signal’s playback speed without changing its pitch. In digital music production, TSM has become an indispensable tool, which is nowadays integrated in a wide range of music production software. Music signals are diverse—they comprise harmonic, percussive, and transient components, among others. Because of this wide range of acoustic and musical characteristics, there is no single TSM method that can cope with all kinds of audio signals equally well. Our main objective is to foster a better understanding of the capabilities and limitations of TSM procedures. To this end, we review fundamental TSM methods, discuss typical challenges, and indicate potential solutions that combine different strategies. In particular, we discuss a fusion approach that involves recent techniques for harmonic-percussive separation along with time-domain and frequency-domain TSM procedures.
Estimating ventilation time scales using overturning stream functions
Thompson, Bijoy; Nycander, Jonas; Nilsson, Johan; Jakobsson, Martin; Döös, Kristofer
2014-06-01
A simple method for estimating ventilation time scales from overturning stream functions is proposed. The stream function may be computed using either geometric coordinates or a generalized vertical coordinate, such as potential density (salinity in our study). The method is tested with a three-dimensional circulation model describing an idealized semi-enclosed ocean basin ventilated through a narrow strait over a sill, and the result is compared to age estimates obtained from a passive numerical age tracer. The best result is obtained when using the stream function in salinity coordinates. In this case, the reservoir-averaged advection time obtained from the overturning stream function in salinity coordinates agrees rather well with the mean age of the age tracer, and the corresponding maximum ages agree very well.
Generalized dynamic scaling for quantum critical relaxation in imaginary time.
Zhang, Shuyi; Yin, Shuai; Zhong, Fan
2014-10-01
We study the imaginary-time relaxation critical dynamics of a quantum system with a vanishing initial correlation length and an arbitrary initial order parameter M0. We find that in quantum critical dynamics, the behavior of M0 under scale transformations deviates from a simple power law, which was proposed for very small M0 previously. A universal characteristic function is then suggested to describe the rescaled initial magnetization, similar to classical critical dynamics. This characteristic function is shown to be able to describe the quantum critical dynamics in both short- and long-time stages of the evolution. The one-dimensional transverse-field Ising model is employed to numerically determine the specific form of the characteristic function. We demonstrate that it is applicable as long as the system is in the vicinity of the quantum critical point. The universality of the characteristic function is confirmed by numerical simulations of models belonging to the same universality class.
Jørgensen, John Bagterp; Jørgensen, Sten Bay
2007-01-01
model is realized from a continuous-discrete-time linear stochastic system specified using transfer functions with time-delays. It is argued that the prediction-error criterion should be selected such that it is compatible with the objective function of the predictive controller in which the model......A Prediction-error-method tailored for model based predictive control is presented. The prediction-error method studied are based on predictions using the Kalman filter and Kalman predictors for a linear discrete-time stochastic state space model. The linear discrete-time stochastic state space...
MULTI SCALE TIME SERIES PREDICTION FOR INTRUSION DETECTION
G. Palanivel
2014-01-01
Full Text Available We propose an anomaly-based network intrusion detection system, which analyzes traffic features to detect anomalies. The proposed system can be used both in online as well as off-line mode for detecting deviations from the expected behavior. Although our approach uses network packet or flow data, it is general enough to be adaptable for use with any other network variable, which may be used as a signal for anomaly detection. It differs from most existing approaches in its use of wavelet transform for generating different time scales for a signal and using these scales as an input to a two-stage neural network predictor. The predictor predicts the expected signal value and labels considerable deviations from this value as anomalies. The primary contribution of our work would be to empirically evaluate the effectiveness of multi resolution analysis as an input to neural network prediction engine specifically for the purpose of intrusion detection. The role of Intrusion Detection Systems (IDSs, as special-purpose devices to detect anomalies and attacks in a network, is becoming more important. First, anomaly-based methods cannot achieve an outstanding performance without a comprehensive labeled and up-to-date training set with all different attack types, which is very costly and time-consuming to create if not impossible. Second, efficient and effective fusion of several detection technologies becomes a big challenge for building an operational hybrid intrusion detection system.
Reusable Launch Vehicle Control In Multiple Time Scale Sliding Modes
Shtessel, Yuri; Hall, Charles; Jackson, Mark
2000-01-01
A reusable launch vehicle control problem during ascent is addressed via multiple-time scaled continuous sliding mode control. The proposed sliding mode controller utilizes a two-loop structure and provides robust, de-coupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of bounded external disturbances and plant uncertainties. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues placement. Overall stability of a two-loop control system is addressed. An optimal control allocation algorithm is designed that allocates torque commands into end-effector deflection commands, which are executed by the actuators. The dual-time scale sliding mode controller was designed for the X-33 technology demonstration sub-orbital launch vehicle in the launch mode. Simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in presence of external disturbances and vehicle inertia uncertainties. This is a significant advancement in performance over that achieved with linear, gain scheduled control systems currently being used for launch vehicles.
Cell assemblies at multiple time scales with arbitrary lag constellations
Russo, Eleonora; Durstewitz, Daniel
2017-01-01
Hebb's idea of a cell assembly as the fundamental unit of neural information processing has dominated neuroscience like no other theoretical concept within the past 60 years. A range of different physiological phenomena, from precisely synchronized spiking to broadly simultaneous rate increases, has been subsumed under this term. Yet progress in this area is hampered by the lack of statistical tools that would enable to extract assemblies with arbitrary constellations of time lags, and at multiple temporal scales, partly due to the severe computational burden. Here we present such a unifying methodological and conceptual framework which detects assembly structure at many different time scales, levels of precision, and with arbitrary internal organization. Applying this methodology to multiple single unit recordings from various cortical areas, we find that there is no universal cortical coding scheme, but that assembly structure and precision significantly depends on the brain area recorded and ongoing task demands. DOI: http://dx.doi.org/10.7554/eLife.19428.001 PMID:28074777
Designing for development: Across the scales of time.
Cole, Michael
2016-11-01
This essay traces the history of an activity designed to promote the intellectual and social development of elementary-age schoolchildren during the afterschool hours. Following in the footsteps of Urie Bronfenbrenner, I highlight his argument that just as all human development occurs in contexts of varying levels of inclusiveness and mutual interchange, human development occurs at intersecting scales of time that themselves vary in character and duration. The task of exploring Bronfenbrenner's idea confronts scholars interested in person-context coconstitutive processes with a difficult methodological requirement; they must study simultaneously the history of persons (at the microgenetic and ontogenetic time scales) as well the history of "the contexts of development" in which the persons participate. A project implementing such a study focused on the life course of the system of activity is described, followed by a discussion of the lessons to be learned from a temporally extensive study of persons developing in contexts that are themselves changing. (PsycINFO Database Record
Complex processes from dynamical architectures with time-scale hierarchy.
Dionysios Perdikis
Full Text Available The idea that complex motor, perceptual, and cognitive behaviors are composed of smaller units, which are somehow brought into a meaningful relation, permeates the biological and life sciences. However, no principled framework defining the constituent elementary processes has been developed to this date. Consequently, functional configurations (or architectures relating elementary processes and external influences are mostly piecemeal formulations suitable to particular instances only. Here, we develop a general dynamical framework for distinct functional architectures characterized by the time-scale separation of their constituents and evaluate their efficiency. Thereto, we build on the (phase flow of a system, which prescribes the temporal evolution of its state variables. The phase flow topology allows for the unambiguous classification of qualitatively distinct processes, which we consider to represent the functional units or modes within the dynamical architecture. Using the example of a composite movement we illustrate how different architectures can be characterized by their degree of time scale separation between the internal elements of the architecture (i.e. the functional modes and external interventions. We reveal a tradeoff of the interactions between internal and external influences, which offers a theoretical justification for the efficient composition of complex processes out of non-trivial elementary processes or functional modes.
Complex processes from dynamical architectures with time-scale hierarchy.
Perdikis, Dionysios; Huys, Raoul; Jirsa, Viktor
2011-02-10
The idea that complex motor, perceptual, and cognitive behaviors are composed of smaller units, which are somehow brought into a meaningful relation, permeates the biological and life sciences. However, no principled framework defining the constituent elementary processes has been developed to this date. Consequently, functional configurations (or architectures) relating elementary processes and external influences are mostly piecemeal formulations suitable to particular instances only. Here, we develop a general dynamical framework for distinct functional architectures characterized by the time-scale separation of their constituents and evaluate their efficiency. Thereto, we build on the (phase) flow of a system, which prescribes the temporal evolution of its state variables. The phase flow topology allows for the unambiguous classification of qualitatively distinct processes, which we consider to represent the functional units or modes within the dynamical architecture. Using the example of a composite movement we illustrate how different architectures can be characterized by their degree of time scale separation between the internal elements of the architecture (i.e. the functional modes) and external interventions. We reveal a tradeoff of the interactions between internal and external influences, which offers a theoretical justification for the efficient composition of complex processes out of non-trivial elementary processes or functional modes.
Yuan Zhencai; Zhang Xuefeng; Deng Yunqing; Wu Chengkui; Cao Ruiling; Peng Quansheng
2007-01-01
Objective: Study the influence of the stop time in winter, times of plateau on the index in early days for plateau constructors meet; Method: Is it participate in plateau construction of 2002-2004 to choose, enter into the plateau again of 2003-2005 practise clothes finish to mate 326 materials "physical examination in front of the worker", which is passed in Nanshankou Hospital in early days, divided into 3 groups according to the difference of year for the physical examination, examine by leaning towards relevant analytical methods; Result: (1) In the situation of day controlling about the stop time in winter, times of garrison in plateau and blood and oxygen saturation lever ( SaO2 ), the systolic pressure (sBP) is presented and shouldered relevantly winter to control. Present positive correlation with the value of hemoglobin (Hb) ; (2) It is stopped that in case of controlling and is garrisoned in the number of times of plateau in winter day and blood and oxygen saturation lever (SaO2) to present positive correlation. Present and shoulder with the hemoglobin (Hb) relevantly. Conclusion: In order to ensure the health of plateau constructors to the maximum extent, should try one's best to reduce the number of times of returning to the plateau in possible cases. At the same time each one constructs for year and returns to the time that the hinterland concentrates rest should be on above 90 days.
How noise contributes to time-scale invariance of interval timing
Oprisan, Sorinel A.; Buhusi, Catalin V.
2013-05-01
Time perception in the suprasecond range is crucial for fundamental cognitive processes such as decision making, rate calculation, and planning. In the vast majority of species, behavioral manipulations, and neurophysiological manipulations, interval timing is scale invariant: the time-estimation errors are proportional to the estimated duration. The origin and mechanisms of this fundamental property are unknown. We discuss the computational properties of a circuit consisting of a large number of (input) neural oscillators projecting on a small number of (output) coincidence detector neurons, which allows time to be coded by the pattern of coincidental activation of its inputs. We show that time-scale invariance emerges from the neural noise, such as small fluctuations in the firing patterns of its input neurons and in the errors with which information is encoded and retrieved by its output neurons. In this architecture, time-scale invariance is resistant to manipulations as it depends neither on the details of the input population nor on the distribution probability of noise.
Voigt, C.; Denker, H.; Timmen, L.
2016-12-01
The latest generation of optical atomic clocks is approaching the level of one part in 1018 in terms of frequency stability and uncertainty. For clock comparisons and the definition of international time scales, a relativistic redshift effect of the clock frequencies has to be taken into account at a corresponding uncertainty level of about 0.1 m2 s-2 and 0.01 m in terms of gravity potential and height, respectively. Besides the predominant static part of the gravity potential, temporal variations must be considered in order to avoid systematic frequency shifts. Time-variable gravity potential components induced by tides and non-tidal mass redistributions are investigated with regard to the level of one part in 1018. The magnitudes and dominant time periods of the individual gravity potential contributions are investigated globally and for specific laboratory sites together with the related uncertainty estimates. The basics of the computation methods are presented along with the applied models, data sets and software. Solid Earth tides contribute by far the most dominant signal with a global maximum amplitude of 4.2 m2 s-2 for the potential and a range (maximum-to-minimum) of up to 1.3 and 10.0 m2 s-2 in terms of potential differences between specific laboratories over continental and intercontinental scales, respectively. Amplitudes of the ocean tidal loading potential can amount up to 1.25 m2 s-2, while the range of the potential between specific laboratories is 0.3 and 1.1 m2 s-2 over continental and intercontinental scales, respectively. These are the only two contributors being relevant at a 10-17 level. However, several other time-variable potential effects can particularly affect clock comparisons at the 10-18 level. Besides solid Earth pole tides, these are non-tidal mass redistributions in the atmosphere, the oceans and the continental water storage.
Characterization of Microbial Fuel Cells at Microbially and Electrochemically Meaningful Time scales
Ren, Zhiyong
2011-03-15
The variable biocatalyst density in a microbial fuel cell (MFC) anode biofilm is a unique feature of MFCs relative to other electrochemical systems, yet performance characterizations of MFCs typically involve analyses at electrochemically relevant time scales that are insufficient to account for these variable biocatalyst effects. This study investigated the electrochemical performance and the development of anode biofilm architecture under different external loadings, with duplicate acetate-fed singlechamber MFCs stabilized at each resistance for microbially relevant time scales. Power density curves from these steady-state reactors generally showed comparable profiles despite the fact that anode biofilm architectures and communities varied considerably, showing that steady-state biofilm differences had little influence on electrochemical performance until the steady-state external loading was much larger than the reactor internal resistance. Filamentous bacteria were dominant on the anodes under high external resistances (1000 and 5000 Ω), while more diverse rod-shaped cells formed dense biofilms under lower resistances (10, 50, and 265 Ω). Anode charge transfer resistance decreased with decreasing fixed external resistances, but was consistently 2 orders of magnitude higher than the resistance at the cathode. Cell counting showed an inverse exponential correlation between cell numbers and external resistances. This direct link ofMFCanode biofilm evolution with external resistance and electricity production offers several operational strategies for system optimization. © 2011 American Chemical Society.
Albijanic, Boris; Ozdemir, Orhan; Nguyen, Anh V; Bradshaw, Dee
2010-08-11
Bubble-particle attachment in water is critical to the separation of particles by flotation which is widely used in the recovery of valuable minerals, the deinking of wastepaper, the water treatment and the oil recovery from tar sands. It involves the thinning and rupture of wetting thin films, and the expansion and relaxation of the gas-liquid-solid contact lines. The time scale of the first two processes is referred to as the induction time, whereas the time scale of the attachment involving all the processes is called the attachment time. This paper reviews the experimental studies into the induction and attachment times between minerals and air bubbles, and between oil droplets and air bubbles. It also focuses on the experimental investigations and mathematical modelling of elementary processes of the wetting film thinning and rupture, and the three-phase contact line expansion relevant to flotation. It was confirmed that the time parameters, obtained by various authors, are sensitive enough to show changes in both flotation surface chemistry and physical properties of solid surfaces of pure minerals. These findings should be extended to other systems. It is proposed that measurements of the bubble-particle attachment can be used to interpret changes in flotation behaviour or, in conjunction with other factors, such as particle size and gas dispersion, to predict flotation performance.
Modelling Time and Length Scales of Scour Around a Pipeline
Smith, H. D.; Foster, D. L.
2002-12-01
The scour and burial of submarine objects is an area of interest for engineers, oceanographers and military personnel. Given the limited availability of field observations, there exists a need to accurately describe the hydrodynamics and sediment response around an obstacle using numerical models. In this presentation, we will compare observations of submarine pipeline scour with model predictions. The research presented here uses the computational fluid dynamics (CFD) model FLOW-3D. FLOW-3D, developed by Flow Science in Santa Fe, NM, is a 3-dimensional finite-difference model that solves the Navier-Stokes and continuity equations. Using the Volume of Fluid (VOF) technique, FLOW-3D is able to resolve fluid-fluid and fluid-air interfaces. The FAVOR technique allows for complex geometry to be resolved with rectangular grids. FLOW-3D uses a bulk transport method to describe sediment transport and feedback to the hydrodynamic solver is accomplished by morphology evolution and fluid viscosity due to sediment suspension. Previous investigations by the authors have shown FLOW-3D to well-predict the hydrodynamics around five static scoured bed profiles and a stationary pipeline (``Modelling of Flow Around a Cylinder Over a Scoured Bed,'' submit to Journal of Waterway, Port, Coastal, and Ocean Engineering). Following experiments performed by Mao (1986, Dissertation, Technical University of Denmark), we will be performing model-data comparisons of length and time scales for scour around a pipeline. Preliminary investigations with LES and k-ɛ closure schemes have shown that the model predicts shorter time scales in scour hole development than that observed by Mao. Predicted time and length scales of scour hole development are shown to be a function of turbulence closure scheme, grain size, and hydrodynamic forcing. Subsequent investigations consider variable wave-current flow regimes and object burial. This investigation will allow us to identify different regimes for the
Time-Scale Domain Characterization of Time-Varying Ultrawideband Infostation Channel
U.A.K. Chude-Okonkwo
2012-06-01
Full Text Available The time-scale domain geometrical-based method for the characterization of the time varying ultrawideband (UWB channel typical of an infostation channel is presented. Compared to methods that use Doppler shift as a measure of time-variation in the channel this model provides a more reliable measure of frequency dispersion caused by terminal mobility in the UWB infostation channel. Particularly, it offers carrier frequency independent method of computing wideband channel responses and parameters which are important for ultrawideband systems. Results show that the frequency dispersion of the channel depends on the frequency and not on the choice of bandwidth. And time dispersion depends on bandwidth and not on the frequency. It is also shown that for time-varying UWB, frame length defined over the coherence time obtained with reference to the carrier frequency results in an error margin which can be reduced by using the coherence time defined with respect to the maximum frequency in a given frequency band. And the estimation of the frequency offset using the time-scale domain (wideband model presented here (especially in the case of multiband UWB frequency synchronization is more accurate than using frequency offset estimate obtained from narrowband models.
Scaling in Non-stationary time series I
Ignaccolo, M; Grigolini, P; Hamilton, P; West, B J
2003-01-01
Most data processing techniques, applied to biomedical and sociological time series, are only valid for random fluctuations that are stationary in time. Unfortunately, these data are often non stationary and the use of techniques of analysis resting on the stationary assumption can produce a wrong information on the scaling, and so on the complexity of the process under study. Herein, we test and compare two techniques for removing the non-stationary influences from computer generated time series, consisting of the superposition of a slow signal and a random fluctuation. The former is based on the method of wavelet decomposition, and the latter is a proposal of this paper, denoted by us as step detrending technique. We focus our attention on two cases, when the slow signal is a periodic function mimicking the influence of seasons, and when it is an aperiodic signal mimicking the influence of a population change (increase or decrease). For the purpose of computational simplicity the random fluctuation is taken...
Multi-scale gravity field modeling in space and time
Wang, Shuo; Panet, Isabelle; Ramillien, Guillaume; Guilloux, Frédéric
2016-04-01
The Earth constantly deforms as it undergoes dynamic phenomena, such as earthquakes, post-glacial rebound and water displacement in its fluid envelopes. These processes have different spatial and temporal scales and are accompanied by mass displacements, which create temporal variations of the gravity field. Since 2002, the GRACE satellite missions provide an unprecedented view of the gravity field spatial and temporal variations. Gravity models built from these satellite data are essential to study the Earth's dynamic processes (Tapley et al., 2004). Up to present, time variations of the gravity field are often modelled using spatial spherical harmonics functions averaged over a fixed period, as 10 days or 1 month. This approach is well suited for modeling global phenomena. To better estimate gravity related to local and/or transient processes, such as earthquakes or floods, and adapt the temporal resolution of the model to its spatial resolution, we propose to model the gravity field using localized functions in space and time. For that, we build a model of the gravity field in space and time with a four-dimensional wavelet basis, well localized in space and time. First we design the 4D basis, then, we study the inverse problem to model the gravity field from the potential differences between the twin GRACE satellites, and its regularization using prior knowledge on the water cycle. Our demonstration of surface water mass signals decomposition in time and space is based on the use of synthetic along-track gravitational potential data. We test the developed approach on one year of 4D gravity modeling and compare the reconstructed water heights to those of the input hydrological model. Perspectives of this work is to apply the approach on real GRACE data, addressing the challenge of a realistic noise, to better describe and understand physical processus with high temporal resolution/low spatial resolution or the contrary.
Scale-free networks emerging from multifractal time series
Budroni, Marcello A.; Baronchelli, Andrea; Pastor-Satorras, Romualdo
2017-05-01
Methods connecting dynamical systems and graph theory have attracted increasing interest in the past few years, with applications ranging from a detailed comparison of different kinds of dynamics to the characterization of empirical data. Here we investigate the effects of the (multi)fractal properties of a signal, common in time series arising from chaotic dynamics or strange attractors, on the topology of a suitably projected network. Relying on the box-counting formalism, we map boxes into the nodes of a network and establish analytic expressions connecting the natural measure of a box with its degree in the graph representation. We single out the conditions yielding to the emergence of a scale-free topology and validate our findings with extensive numerical simulations. We finally present a numerical analysis on the properties of weighted and directed network projections.
Scale-free networks emerging from multifractal time series.
Budroni, Marcello A; Baronchelli, Andrea; Pastor-Satorras, Romualdo
2017-05-01
Methods connecting dynamical systems and graph theory have attracted increasing interest in the past few years, with applications ranging from a detailed comparison of different kinds of dynamics to the characterization of empirical data. Here we investigate the effects of the (multi)fractal properties of a signal, common in time series arising from chaotic dynamics or strange attractors, on the topology of a suitably projected network. Relying on the box-counting formalism, we map boxes into the nodes of a network and establish analytic expressions connecting the natural measure of a box with its degree in the graph representation. We single out the conditions yielding to the emergence of a scale-free topology and validate our findings with extensive numerical simulations. We finally present a numerical analysis on the properties of weighted and directed network projections.
Empirical mode decomposition using variable filtering with time scale calibrating
无
2008-01-01
A novel and efficient method for decomposing a signal into a set of intrinsic mode functions (IMFs) and a trend is proposed. Unlike the original empirical mode decomposition (EMD), which uses spline fits to extract variations from the signal by separating the local mean from the fluctuations in the decomposing process, this new method being proposed takes advantage of the theory of variable finite impulse response (FIR) filtering where filter coefficients and breakpoint frequencies can be adjusted to track any peak-to-peak time scale changes. The IMFs are results of a multiple variable frequency response FIR filtering when signals pass through the filters. Numerical examples validate that in contrast with the original EMD, the proposed method can fine-tune the frequency resolution and suppress the aliasing effectively.
Nonoscillation for second order sublinear dynamic equations on time scales
Erbe, Lynn; Baoguo, Jia; Peterson, Allan
2009-10-01
Consider the Emden-Fowler sublinear dynamic equation x[Delta][Delta](t)+p(t)f(x([sigma](t)))=0, where , is a time scale, , where ai>0, 0researchers. In this paper, we allow the coefficient function p(t) to be negative for arbitrarily large values of t. We extend a nonoscillation result of Wong for the second order sublinear Emden-Fowler equation in the continuous case to the dynamic equation (0.1). As applications, we show that the sublinear difference equation has a nonoscillatory solution, for b>0, c>[alpha], and the sublinear q-difference equation has a nonoscillatory solution, for , q>1, b>0, c>1+[alpha].
On the superposition of heterogeneous traffic at large time scales
Sidney I. Resnick
2011-01-01
Full Text Available Various empirical and theoretical studies indicate that cumulative network traffic is a Gaussian process. However, depending on whether the intensity at which sessions are initiated is large or small relative to the session duration tail, [25] and [15] have shown that traffic at large time scales can be approximated by either fractional Brownian motion (fBm or stable Lévy motion. We study distributional properties of cumulative traffic that consists of a finite number of independent streams and give an explanation of why Gaussian examples abound in practice but not stable Lévy motion. We offer an explanation of how much vertical aggregation is needed for the Gaussian approximation to hold. Our results are expressed as limit theorems for a sequence of cumulative traffic processes whose session initiation intensities satisfy growth rates similar to those used in [25].
Variation of atmospheric depth profile on different time scales
Wilczynska, B; Homola, P; Pekala, J; Risse, M; Wilczynski, H
2006-01-01
The vertical profile of atmospheric depth is an important element in extensive air shower studies. The depth of shower maximum is one of the most important characteristics of the shower. In the fluorescence technique of shower detection, the geometrical reconstruction provides the altitude of shower maximum, so that an accurate profile of atmospheric depth is needed to convert this altitude to the depth of shower maximum. In this paper the temporal variation of experimentally measured profiles of atmospheric depth at different sites is studied and implications for shower reconstruction are shown. The atmospheric profiles vary on time scales from hours to years. It is shown that the daily variation of the profile is as important as its seasonal variation and should be accounted for in air shower studies. For precise shower reconstruction, the daily profiles determined locally at the site of the air shower detector are recommended.
Large-scale structure of time evolving citation networks
Leicht, E. A.; Clarkson, G.; Shedden, K.; Newman, M. E. J.
2007-09-01
In this paper we examine a number of methods for probing and understanding the large-scale structure of networks that evolve over time. We focus in particular on citation networks, networks of references between documents such as papers, patents, or court cases. We describe three different methods of analysis, one based on an expectation-maximization algorithm, one based on modularity optimization, and one based on eigenvector centrality. Using the network of citations between opinions of the United States Supreme Court as an example, we demonstrate how each of these methods can reveal significant structural divisions in the network and how, ultimately, the combination of all three can help us develop a coherent overall picture of the network's shape.
Relevance of emissions timing in biofuel greenhouse gases and climate impacts.
Schwietzke, Stefan; Griffin, W Michael; Matthews, H Scott
2011-10-01
Employing life cycle greenhouse gas (GHG) emissions as a key performance metric in energy and environmental policy may underestimate actual climate change impacts. Emissions released early in the life cycle cause greater cumulative radiative forcing (CRF) over the next decades than later emissions. Some indicate that ignoring emissions timing in traditional biofuel GHG accounting overestimates the effectiveness of policies supporting corn ethanol by 10-90% due to early land use change (LUC) induced GHGs. We use an IPCC climate model to (1) estimate absolute CRF from U.S. corn ethanol and (2) quantify an emissions timing factor (ETF), which is masked in the traditional GHG accounting. In contrast to earlier analyses, ETF is only 2% (5%) over 100 (50) years of impacts. Emissions uncertainty itself (LUC, fuel production period) is 1-2 orders of magnitude higher, which dwarfs the timing effect. From a GHG accounting perspective, emissions timing adds little to our understanding of the climate impacts of biofuels. However, policy makers should recognize that ETF could significantly decrease corn ethanol's probability of meeting the 20% GHG reduction target in the 2007 Energy Independence and Security Act. The added uncertainty of potentially employing more complex emissions metrics is yet to be quantified.
Livas, Christos; Pandis, Nikolaos; Ren, Yijin
2015-01-01
Introduction: As the importance of systematic review (SR) conclusions relies upon the scientific rigor of methods and the currency of evidence, we aimed to investigate the currency of orthodontic SRs using as proxy the time from the initial search to publication. Additionally, SR information regardi
Livas, Christos; Pandis, Nikolaos; Ren, Yijin
Introduction: As the importance of systematic review (SR) conclusions relies upon the scientific rigor of methods and the currency of evidence, we aimed to investigate the currency of orthodontic SRs using as proxy the time from the initial search to publication. Additionally, SR information
Marine Dispersal Scales Are Congruent over Evolutionary and Ecological Time
Pinsky, Malin L.
2016-12-15
The degree to which offspring remain near their parents or disperse widely is critical for understanding population dynamics, evolution, and biogeography, and for designing conservation actions. In the ocean, most estimates suggesting short-distance dispersal are based on direct ecological observations of dispersing individuals, while indirect evolutionary estimates often suggest substantially greater homogeneity among populations. Reconciling these two approaches and their seemingly competing perspectives on dispersal has been a major challenge. Here we show for the first time that evolutionary and ecological measures of larval dispersal can closely agree by using both to estimate the distribution of dispersal distances. In orange clownfish (Amphiprion percula) populations in Kimbe Bay, Papua New Guinea, we found that evolutionary dispersal kernels were 17 km (95% confidence interval: 12–24 km) wide, while an exhaustive set of direct larval dispersal observations suggested kernel widths of 27 km (19–36 km) or 19 km (15–27 km) across two years. The similarity between these two approaches suggests that ecological and evolutionary dispersal kernels can be equivalent, and that the apparent disagreement between direct and indirect measurements can be overcome. Our results suggest that carefully applied evolutionary methods, which are often less expensive, can be broadly relevant for understanding ecological dispersal across the tree of life.
Decomposition of wind speed fluctuations at different time scales
Qinmin Zheng; S Rehman; Md Mahbub Alam; L M Alhems; A Lashin
2017-04-01
Understanding the inherent features of wind speed (variability on different time scales) has become critical for assured wind power availability, grid stability, and effective power management. The study utilizes the wavelet, autocorrelation, and FFT (fast Fourier transform) techniques to analyze and assimilate the fluctuating nature of wind speed data collected over a period of 29–42 years at different locations in the Kingdom of Saudi Arabia. The analyses extracted the intrinsic features of wind speed, including the long-term mean wind speed and fluctuations at different time scales (periods), which is critical for meteorological purposes including wind power resource assessment and weather forecasting. The longterm mean wind speed varied between 1.45 m/s at Mecca station and 3.73 m/s at Taif. The annual variation is the largest (±0.97 m/s) at Taif and the smallest (±0.25 m/s) at Mecca. Similarly, the wind speed fluctuation with different periods was also discussed in detail. The spectral characteristics obtained using FFT reveal that Al-Baha, Najran, Taif and Wadi-Al-Dawasser having a sharp peak at a frequency f = 0.00269 (1/day) retain a more regular annual repetition of wind speed than Bisha, Khamis-Mushait, Madinah, Mecca, and Sharourah. Based on the autocorrelation analysis and FFT results, the stations are divided into three groups: (i) having strong annual modulations (Al-Baha, Najran, Taif and Wadi-Al-Dawasser), (ii) having comparable annual and half-yearly modulations (Bisha, Khamis-Mushait, and Mecca) and (iii) having annual modulation moderately prominent (Madinah and Sharourah).
D. R.
2016-02-01
Full Text Available The possibility of the designing test-systems for specific detection of corrosive-relevant sulfate-reducing bacteria using real-time PCR assay were investigated. This method of the bacteria identification is based on the detection of the functional genes, encoding key enzymes of dissimilatory sulfate-reduction pathway, i.e. dissimilatory sulfitreductase α subunit dsrA. It was established among the six test-systems specificity reveal only three designed on the base of Desulfotomaculum, Desulfovibrio, Desulfobulbus genera sequences. The most corrosive-relevant strain Desulfovibrio sp. UCM B-11503 dsrA gene detected more effectively (threshold cycle was 20,0, than less corrosive-relevant strains Desulfovibrio sp. UCM B-11504 (threshold cycle was 28,1 and for Desulfotomaculum sp. UCM B-11505 and Desulfomicrobium sp. UCМ B-11506 were 24,9 and 23,1 cycles, respectively. Test-systems allowed identifying corrosive-relevant sulfate-reducing bacteria faster and more effective. This approach will serve as a base for monitoring of these bacteria for estimating corrosion sites on the high-level dangerous man-caused objects.
Towards a stable numerical time scale for the early Paleogene
Hilgen, Frederik; Kuiper, Klaudia; Sierro, Francisco J.; Wotzlaw, Jorn; Schaltegger, Urs; Sahy, Diana; Condon, Daniel
2014-05-01
The construction of an astronomical time scale for the early Paleogene is hampered by ambiguities in the number, correlation and tuning of 405-kyr eccentricity related cycles in deep marine records from ODP cores and land-based sections. The two most competing age models result in astronomical ages for the K/Pg boundary that differ by ~750 kyr (~66.0 Ma of Vandenberghe et al. (2012) versus 65.25 Ma of Westerhold et al. (2012); these ages in turn are consistent with proposed ages for the Fish Canyon sanidine (FCs) that differ by ~300 kyr (28.201 Ma of Kuiper et al. (2008) versus 27.89 Ma of Westerhold et al. (2012)); an even older age of 28.294 Ma is proposed based on a statistical optimization model (Renne et al., 2011). The astronomically calibrated FCs age of 28.201 ± 0.046 Ma of Kuiper et al. (2008), which is consistent with the astronomical age of ~66.0 Ma for the K/Pg boundary, is currently adopted in the standard geological time scale (GTS2012). Here we combine new and published data in an attempt to solve the controversy and arrive at a stable nuemrical time scale for the early Paleogene. Supporting their younger age model, Westerhold et al. (2012) argue that the tuning of Miocene sections in the Mediterranean, which underlie the older FCs age of Kuiper et al. (2008) and, hence, the coupled older early Paleogene age model of Vandenberghe et al. (2012), might be too old by three precession cycles. We thoroughly rechecked this tuning; distinctive cycle patterns related to eccentricity and precession-obliquity interference make a younger tuning that would be consistent with the younger astronomical age of 27.89 Ma for the FCs of Westerhold et al. (2012) challenging. Next we compared youngest U/Pb zircon and astronomical ages for a number of ash beds in the tuned Miocene section of Monte dei Corvi. These ages are indistinguishable, indicating that the two independent dating methods yield the same age when the same event is dated. This is consistent with results
The stochastic background: scaling laws and time to detection for pulsar timing arrays
Siemens, Xavier; Jenet, Fredrick; Romano, Joseph D
2013-01-01
We derive scaling laws for the signal-to-noise ratio of the optimal cross-correlation statistic, and show that the large power-law increase of the signal-to-noise ratio as a function of the the observation time $T$ that is usually assumed holds only at early times. After enough time has elapsed, pulsar timing arrays enter a new regime where the signal to noise only scales as $\\sqrt{T}$. In addition, in this regime the quality of the pulsar timing data and the cadence become relatively un-important. This occurs because the lowest frequencies of the pulsar timing residuals become gravitational-wave dominated. Pulsar timing arrays enter this regime more quickly than one might naively suspect. For T=10 yr observations and typical stochastic background amplitudes, pulsars with residual RMSs of less than about $1\\,\\mu$s are already in that regime. The best strategy to increase the detectability of the background in this regime is to increase the number of pulsars in the array. We also perform realistic simulations ...
Relevant Norms of Holy Places and Times in Three Sacred Books
Mohsenian, M; Bahonar, N
2011-01-01
Basically speaking, saintliness is considered as a commented and valued issue allotting to religion realm which without the presence of such a meaning, no religion is worthy of its name. This article aims to consider the normative prepositions related to holy places and times in three sacred books : Quran, Pentateuch, and Gospel with their similarities and differences. A specific software program is used with quantitative and qualitative research method to process and analyz...
Livas, Christos; Pandis, Nikolaos; Ren, Yijin
2015-04-01
As the importance of systematic review (SR) conclusions relies upon the scientific rigor of methods and the currency of evidence, we aimed to investigate the currency of orthodontic SRs using as proxy the time from the initial search to publication. Additionally, SR information regarding reporting guidelines, registration, and literature searches were recorded when available. A systematic PubMed search was carried out using the Clinical Queries page to identify orthodontic SRs cited between 1 January 2008 and 7 November 2013. Data related to reporting guidelines, review registration, dates of review processing, literature search, and abstract reporting were retrieved and classified by journal type. Survival analysis was used to assess the time to reach predefined manuscript stages for orthodontic and non-orthodontic journals. One hundred twenty seven of the originally identified 585 SRs were considered eligible. The median interval from search until publication was 13.2 months (interquartile range: IQR = 9.7 months) irrespective of the journal type. There was evidence (P = 0.05) that SRs published by non-orthodontic journals appeared in PubMed faster than in orthodontic journals (non-orthodontic: median = 6.5 months; IQR = 5.7 months; orthodontic: median = 10.2 months; IQR = 5.6 months) from submission to publication and from acceptance to publication (non-orthodontic: median = 1.5 months; IQR = 2.4 months; orthodontic: median = 6.0 months; IQR = 6.2 months; P orthodontic and orthodontic periodicals, respectively. This study indicates that SR users should be aware that median time for orthodontic SRs from search to publication is 13.2 months. SRs published in non-orthodontic journals are likely to be more current in terms of submission until time to publication and acceptance until time to publication compared with those published in orthodontic journals. © The Author 2014. Published by Oxford University Press on behalf of the European Orthodontic Society. All
THz time scale structural rearrangements and binding modes in lysozyme-ligand interactions.
Woods, K N
2014-03-01
Predicting the conformational changes in proteins that are relevant for substrate binding is an ongoing challenge in the aim of elucidating the functional states of proteins. The motions that are induced by protein-ligand interactions are governed by the protein global modes. Our measurements indicate that the detected changes in the global backbone motion of the enzyme upon binding reflect a shift from the large-scale collective dominant mode in the unbound state towards a functional twisting deformation that assists in closing the binding cleft. Correlated motion in lysozyme has been implicated in enzyme function in previous studies, but detailed characterization of the internal fluctuations that enable the protein to explore the ensemble of conformations that ultimately foster large-scale conformational change is yet unknown. For this reason, we use THz spectroscopy to investigate the picosecond time scale binding modes and collective structural rearrangements that take place in hen egg white lysozyme (HEWL) when bound by the inhibitor (NAG)3. These protein thermal motions correspond to fluctuations that have a role in both selecting and sampling from the available protein intrinsic conformations that communicate function. Hence, investigation of these fast, collective modes may provide knowledge about the mechanism leading to the preferred binding process in HEWL-(NAG)3. Specifically, in this work we find that the picosecond time scale hydrogen-bonding rearrangements taking place in the protein hydration shell with binding modify the packing density within the hydrophobic core on a local level. These localized, intramolecular contact variations within the protein core appear to facilitate the large cooperative movements within the interfacial region separating the α- and β- domain that mediate binding. The THz time-scale fluctuations identified in the protein-ligand system may also reveal a molecular mechanism for substrate recognition.
Megan Sapp Nelson
2013-03-01
Full Text Available Objective – This study aims to determine if the timing of library in-class presentations makes a difference in the type and quality of resources students use for each of four assignments in an introductory speech class. This comparison of content delivery timing contrasts a single, 50-minute lecture early in the semester with four approximately 12-minute lectures offered just before each assignment.Methods – First-year engineering students taking Fundamentals of Speech Communication provide the study group. Each speech assignment requires students to turn in an outline and list of references. The list of references for each student was given to the librarians, after the assignments were appropriately anonymized, for analysis of resource type, quality of resource, and completeness of citation. Researchers coded arandom sample of bibliographies from the assignments using a framework to identify resource type (book, periodical, Web, facts & figures, unknown and quality, based on intended audience and purpose (scholarly, entertainment, persuasion/bias, and compared them to each other to determine if a difference is evident. The authors coordinated what material would be presented to the students to minimize variation between the sections.Results – The study found a statistically significant difference between groups of students, demonstrating that the frequent, short library instruction sessions produce an increased use of high-quality content. Similarly, the sections with multiple library interactions show more use of periodicals than websites, while completeness of references is not significantly different across teaching methods.Conclusions – More frequent and timely interaction between students and library instruction increases the quality of sources used and the completeness of the citations written. While researchers found statistically significant differences, the use of a citation coding framework developed for specific engineering
Residential Mobility and Turnout: The Relevance of Social Costs, Timing and Education
Hansen, Jonas Hedegaard
2016-01-01
moved from the old neighborhood and it does not matter if citizens change municipality. Thus, the disruption of social ties is the main explanation for the negative effect of moving on turnout. Furthermore, the timing of residential mobility is important as the effect on turnout declines quickly after...... settling down. This illustrates that large events in citizens’ everyday life close to Election Day can distract them from going to the polling station. Finally, residential mobility mostly affects the turnout of less educated citizens. Consequentially, residential mobility increases inequalities in voter...
The pace of aging: Intrinsic time scales in demography
Tomasz Wrycza
2014-05-01
Full Text Available Background: The pace of aging is a concept that captures the time-related aspect of aging. It formalizesthe idea of a characteristic life span or intrinsic population time scale. In the rapidly developing field of comparative biodemography, measures that account for inter-speciesdifferences in life span are needed to compare how species age. Objective: We aim to provide a mathematical foundation for the concept of pace. We derive desiredmathematical properties of pace measures and suggest candidates which satisfy these properties. Subsequently, we introduce the concept of pace-standardization, which reveals differences in demographic quantities that are not due to pace. Examples and consequences are discussed. Conclusions: Mean life span (i.e., life expectancy from birth or from maturity is intuitively appealing,theoretically justified, and the most appropriate measure of pace. Pace-standardizationprovides a serviceable method for comparative aging studies to explore differences indemographic patterns of aging across species, and it may considerably alter conclusionsabout the strength of aging.
Selective attention to temporal features on nested time scales.
Henry, Molly J; Herrmann, Björn; Obleser, Jonas
2015-02-01
Meaningful auditory stimuli such as speech and music often vary simultaneously along multiple time scales. Thus, listeners must selectively attend to, and selectively ignore, separate but intertwined temporal features. The current study aimed to identify and characterize the neural network specifically involved in this feature-selective attention to time. We used a novel paradigm where listeners judged either the duration or modulation rate of auditory stimuli, and in which the stimulation, working memory demands, response requirements, and task difficulty were held constant. A first analysis identified all brain regions where individual brain activation patterns were correlated with individual behavioral performance patterns, which thus supported temporal judgments generically. A second analysis then isolated those brain regions that specifically regulated selective attention to temporal features: Neural responses in a bilateral fronto-parietal network including insular cortex and basal ganglia decreased with degree of change of the attended temporal feature. Critically, response patterns in these regions were inverted when the task required selectively ignoring this feature. The results demonstrate how the neural analysis of complex acoustic stimuli with multiple temporal features depends on a fronto-parietal network that simultaneously regulates the selective gain for attended and ignored temporal features.
Forecasting decadal and shorter time-scale solar cycle features
Dikpati, Mausumi
2016-07-01
Solar energetic particles and magnetic fields reach the Earth through the interplanetary medium and affect it in various ways, producing beautiful aurorae, but also electrical blackouts and damage to our technology-dependent economy. The root of energetic solar outputs is the solar activity cycle, which is most likely caused by dynamo processes inside the Sun. It is a formidable task to accurately predict the amplitude, onset and peak timings of a solar cycle. After reviewing all solar cycle prediction methods, including empirical as well as physical model-based schemes, I will describe what we have learned from both validation and nonvalidation of cycle 24 forecasts, and how to refine the model-based schemes for upcoming cycle 25 forecasts. Recent observations indicate that within a solar cycle there are shorter time-scale 'space weather' features, such as bursts of various forms of activity with approximately one year periodicity. I will demonstrate how global tachocline dynamics could play a crucial role in producing such space weather. The National Center for Atmospheric Research is sponsored by the National Science Foundation.
The quenching time scale and quenching rate of galaxies
Lian, Jianhui; Zhang, Kai; Kong, Xu
2016-01-01
The average star formation rate (SFR) in galaxies has been declining since redshift of 2. A fraction of galaxies quench and become quiescent. We constrain two key properties of the quenching process: the quenching time scale and the quenching rate among galaxies. We achieve this by analyzing the galaxy number density profile in NUV-u color space and the distribution in NUV-u v.s. u-i color-color diagram with a simple toy-model framework. We focus on galaxies in three mass bins between 10 to 10 and 10 to 10.6 solar mass. In the NUV-u v.s. u-i color-color diagram, the red u-i galaxies exhibit a different slope from the slope traced by the star-forming galaxies. This angled distribution and the number density profile of galaxies in NUV-u space strongly suggest that the decline of the SFR in galaxies has to accelerate before they turn quiescent. We model this color-color distribution with a two-phase exponential decline star formation history. The models with an e-folding time in the second phase (the quenching p...
Brask, Jonatan Bohr; Brunner, Nicolas
2015-12-01
A small quantum absorption refrigerator, consisting of three qubits, is discussed in the transient regime. We discuss time scales for coherent dynamics, damping, and approach to the steady state, and we study cooling and entanglement. We observe that cooling can be enhanced in the transient regime, in the sense that lower temperatures can be achieved compared to the steady-state regime. This is a consequence of coherent dynamics but can occur even when this dynamics is strongly damped by the dissipative thermal environment, and we note that precise control over couplings or timing is not needed to achieve enhanced cooling. We also show that the amount of entanglement present in the refrigerator can be much larger in the transient regime compared to the steady state. These results are of relevance to future implementations of quantum thermal machines.
Simulations of neutron background in a time projection chamber relevant to dark matter searches
Carson, M J; Daw, E; Hollingworth, R J; Kirkpatrick, J A; Kudryavtsev, V A; Lawson, T B; Lightfoot, P K; McMillan, J E; Morgan, B; Paling, S M; Robinson, M; Spooner, N J C; Tovey, Daniel R; Tziaferi, E
2005-01-01
Presented here are results of simulations of neutron background performed for a time projection chamber acting as a particle dark matter detector in an underground laboratory. The investigated background includes neutrons from rock and detector components, generated via spontaneous fission and (alpha, n) reactions, as well as those due to cosmic-ray muons. Neutrons were propagated to the sensitive volume of the detector and the nuclear recoil spectra were calculated. Methods of neutron background suppression were also examined and limitations to the sensitivity of a gaseous dark matter detector are discussed. Results indicate that neutrons should not limit sensitivity to WIMP-nucleon interactions down to a level of (1 - 3) x 10^{-8} pb in a 10 kg detector.
Sabrina Page
2013-01-01
Full Text Available Communication during an emergency or crisis event is essential for emergency responders, the community involved, and those watching on television as well as receiving information via social media from family members, friends or other community members. The evolution of communication during an emergency/crisis event now includes utilizing social media. To better understand this evolution the Emerging Media Crisis Value Model (EMCVM is used in comparing two emergency events; Hurricane Irene (2011, a natural disaster, and the theater shooting in Aurora, Colorado (2012, a man-made crisis. The EMCVM provides a foundation for future studies focusing on the use of social media, emergency responders at the local, state and national levels are better prepared to educate a community thus, counteracting public uncertainty, fear, while providing timely, accurate information.
Real-time Terrain Relative Navigation Test Results from a Relevant Environment for Mars Landing
Johnson, Andrew E.; Cheng, Yang; Montgomery, James; Trawny, Nikolas; Tweddle, Brent; Zheng, Jason
2015-01-01
Terrain Relative Navigation (TRN) is an on-board GN&C function that generates a position estimate of a spacecraft relative to a map of a planetary surface. When coupled with a divert, the position estimate enables access to more challenging landing sites through pin-point landing or large hazard avoidance. The Lander Vision System (LVS) is a smart sensor system that performs terrain relative navigation by matching descent camera imagery to a map of the landing site and then fusing this with inertial measurements to obtain high rate map relative position, velocity and attitude estimates. A prototype of the LVS was recently tested in a helicopter field test over Mars analog terrain at altitudes representative of Mars Entry Descent and Landing conditions. TRN ran in real-time on the LVS during the flights without human intervention or tuning. The system was able to compute estimates accurate to 40m (3 sigma) in 10 seconds on a flight like processing system. This paper describes the Mars operational test space definition, how the field test was designed to cover that operational envelope, the resulting TRN performance across the envelope and an assessment of test space coverage.
Keller, Delphine [CEA, LIST Service de Robotique Interactive, BP6 F-92265 Fontenay aux Roses Cedex (France)], E-mail: delphine.keller@cea.fr; Bayetti, P. [Association Euratom-CEA, DSM/IRFM, CEA/Cadarache F-13108 Saint Paul Lez Durance Cedex (France); Bonnemason, J. [CEA, LIST Service de Robotique Interactive, BP6 F-92265 Fontenay aux Roses Cedex (France); Bruno, V. [Association Euratom-CEA, DSM/IRFM, CEA/Cadarache F-13108 Saint Paul Lez Durance Cedex (France); Chambaud, P.; Friconneau, J.P. [CEA, LIST Service de Robotique Interactive, BP6 F-92265 Fontenay aux Roses Cedex (France); Gargiulo, L. [Association Euratom-CEA, DSM/IRFM, CEA/Cadarache F-13108 Saint Paul Lez Durance Cedex (France); Itchah, M.; Lamy, S. [CEA, LIST Service de Robotique Interactive, BP6 F-92265 Fontenay aux Roses Cedex (France); Le, R. [Association Euratom-CEA, DSM/IRFM, CEA/Cadarache F-13108 Saint Paul Lez Durance Cedex (France); Measson, Y.; Perrot, Y.; Ponsort, D. [CEA, LIST Service de Robotique Interactive, BP6 F-92265 Fontenay aux Roses Cedex (France)
2009-06-15
In 2008, the Articulated Inspection Arm (AIA) performed its first deployment in Tore Supra tokamak vessel, under real vacuum and temperature conditions (10{sup -6} Pa and 120 deg. C) after a conditioning phase to avoid pollution of the chamber. This full demonstration is a turning point in the project, allowing a second phase to start toward the objective to make use of the Remote Handling Equipment as an inspection routine tool. This feasibility demonstration will also be performed on Tore Supra. At this stage, the system requires enhancements of overall technologies and also developments of the Remote Handling control system. Lessons learned in the first phase of the project and experience collected for more than 20 years by Robotics Units of CEA-LIST teams on teleoperated systems enable to identify three main fields to explore to reach the objectives: - Development of a reliable control based on a real time generic command control system. - Development of a graphical supervisor for intuitive steering. - Development of a generic flexible model for realistic computations of the robot localization in the environment. This paper is dedicated to the description of the further developments that shall be done for routine Remote Handling operations. It presents the R and D project roadmap for the next years.
Speech perception in the child brain: cortical timing and its relevance to literacy acquisition.
Parviainen, Tiina; Helenius, Päivi; Poskiparta, Elisa; Niemi, Pekka; Salmelin, Riitta
2011-12-01
Speech processing skills go through intensive development during mid-childhood, providing basis also for literacy acquisition. The sequence of auditory cortical processing of speech has been characterized in adults, but very little is known about the neural representation of speech sound perception in the developing brain. We used whole-head magnetoencephalography (MEG) to record neural responses to speech and nonspeech sounds in first-graders (7-8-year-old) and compared the activation sequence to that in adults. In children, the general location of neural activity in the superior temporal cortex was similar to that in adults, but in the time domain the sequence of activation was strikingly different. Cortical differentiation between sound types emerged in a prolonged response pattern at about 250 ms after sound onset, in both hemispheres, clearly later than the corresponding effect at about 100 ms in adults that was detected specifically in the left hemisphere. Better reading skills were linked with shorter-lasting neural activation, speaking for interdependence of the maturing neural processes of auditory perception and developing linguistic skills. This study uniquely utilized the potential of MEG in comparing both spatial and temporal characteristics of neural activation between adults and children. Besides depicting the group-typical features in cortical auditory processing, the results revealed marked interindividual variability in children.
Libbey, N P; Chazan, J A; London, M R; Pono, L; Abuelo, J G
1993-04-01
We examined bone biopsies from 47 patients on chronic hemodialysis, and analyzed the histomorphometric and biochemical findings and histologic quantitation of bone aluminium, looking primarily at mineralization lag time (Mlt) to evaluate its usefulness in categorization of renal osteodystrophy (ROD). The patients were categorized as having either relatively normal Mlt ( 100 days, n = 13 patients). The group with relatively normal Mlt showed significantly higher C-terminal parathyroid hormone (PTHc) levels (26,141 +/- 19,270 vs 7,226 +/- 6,073 and 4,434 +/- 4,000 pg/ml) than the moderately or markedly prolonged Mlt groups (p < .01) and was associated with histologic characteristics of osteitis fibrosa or mild hyperparathyroidism (BFR/BS range 0.146-0.947 mcm3/mcm2/d). The group with markedly prolonged Mlt included one patient with classic and 11 with adynamic osteomalacia (BFR/BS range 0.009-0.099) and had greater bone aluminum (Al.S/OS 35.3 +/- 26.7% vs 7.2 +/- 9.0%) than the normal Mlt group (p < .01). The group with moderately prolonged Mlt included two patients with aplastic bone disease (Mlt 80.0 and 84.6 days, and Al.S/OS 100.0 and 72.3%) and 11 patients with features of hyperparathyroidism and osteomalacia (BFR/BS range 0.068-0.243) with variable but generally intermediate bone aluminum deposition (Al.S/OS 22.5 +/- 19.9%). Like BFR/BS and other dynamic parameters Mlt correlates with morphologic types of ROD which primarily reflect bone turnover, but it may also suggest varying degrees of mineralization impairment in a spectrum ranging from high to low turnover types of ROD. Its usefulness in this respect should not be overlooked.
Vaingankar Janhavi
2011-10-01
Full Text Available Abstract Background Instruments to measure mental health and well-being are largely developed and often used within Western populations and this compromises their validity in other cultures. A previous qualitative study in Singapore demonstrated the relevance of spiritual and religious practices to mental health, a dimension currently not included in exiting multi-dimensional measures. The objective of this study was to develop a self-administered measure that covers all key and culturally appropriate domains of mental health, which can be applied to compare levels of mental health across different age, gender and ethnic groups. We present the item reduction and validation of the Positive Mental Health (PMH instrument in a community-based adult sample in Singapore. Methods Surveys were conducted among adult (21-65 years residents belonging to Chinese, Malay and Indian ethnicities. Exploratory and confirmatory factor analysis (EFA, CFA were conducted and items were reduced using item response theory tests (IRT. The final version of the PMH instrument was tested for internal consistency and criterion validity. Items were tested for differential item functioning (DIF to check if items functioned in the same way across all subgroups. Results: EFA and CFA identified six first-order factor structure (General coping, Personal growth and autonomy, Spirituality, Interpersonal skills, Emotional support, and Global affect under one higher-order dimension of Positive Mental Health (RMSEA = 0.05, CFI = 0.96, TLI = 0.96. A 47-item self-administered multi-dimensional instrument with a six-point Likert response scale was constructed. The slope estimates and strength of the relation to the theta for all items in each six PMH subscales were high (range:1.39 to 5.69, suggesting good discrimination properties. The threshold estimates for the instrument ranged from -3.45 to 1.61 indicating that the instrument covers entire spectrums for the six dimensions. The
On the superimposition of heterogeneous traffic at large time scales
Lopez-Oliveros, Luis
2010-01-01
Various empirical and theoretical studies indicate that cumulative network traffic is a Gaussian process. However, depending on whether the intensity at which sessions are initiated is large or small relative to the session duration tail, Mikosch et a. (Ann Appl Probab, 12:23-68, 2002) and Kaj and Taqqu (Progress Probab, 60:383-427, 2008) have shown that traffic at large time scales can be approximated by either fractional Brownian motion (fBm) or stable Levy motion. We study distributional properties of cumulative traffic that consists of a finite number of independent streams and give an explanation of why Gaussian examples abound in practice but not stable Levy motion. We offer an explanation of how much vertical aggregation is needed for the Gaussian approximation to hold. Our results are expressed as limit theorems for a sequence of cumulative traffic processes whose session initiation intensities satisfy growth rates similar to those used in Mikosch et a. (Ann Appl Probab, 12:23-68, 2002).
Evaluating the uncertainty of predicting future climate time series at the hourly time scale
Caporali, E.; Fatichi, S.; Ivanov, V. Y.
2011-12-01
A stochastic downscaling methodology is developed to generate hourly, point-scale time series for several meteorological variables, such as precipitation, cloud cover, shortwave radiation, air temperature, relative humidity, wind speed, and atmospheric pressure. The methodology uses multi-model General Circulation Model (GCM) realizations and an hourly weather generator, AWE-GEN. Probabilistic descriptions of factors of change (a measure of climate change with respect to historic conditions) are computed for several climate statistics and different aggregation times using a Bayesian approach that weights the individual GCM contributions. The Monte Carlo method is applied to sample the factors of change from their respective distributions thereby permitting the generation of time series in an ensemble fashion, which reflects the uncertainty of climate projections of future as well as the uncertainty of the downscaling procedure. Applications of the methodology and probabilistic expressions of certainty in reproducing future climates for the periods, 2000 - 2009, 2046 - 2065 and 2081 - 2100, using the 1962 - 1992 period as the baseline, are discussed for the location of Firenze (Italy). The climate predictions for the period of 2000 - 2009 are tested against observations permitting to assess the reliability and uncertainties of the methodology in reproducing statistics of meteorological variables at different time scales.
Springer, Jan; Goldenberger, Daniel; Schmidt, Friderike; Weisser, Maja; Wehrle-Wieland, Elisabeth; Einsele, Hermann; Frei, Reno; Löffler, Jürgen
2016-03-01
PCR-based detection of Mucorales species could improve diagnosis of suspected invasive fungal infection, leading to a better patient outcome. This study describes two independent probe-based real-time PCR tests for detection of clinically relevant Mucorales, targeting specific fragments of the 18S and the 28S rRNA genes. Both assays have a short turnaround time, allow fast, specific and very sensitive detection of clinically relevant Mucorales and have the potential to be used as quantitative tests. They were validated on various clinical samples (fresh and formalin-fixed paraffin-embedded specimens, mainly biopsies, n = 17). The assays should be used as add-on tools to complement standard techniques; a combined approach of both real-time PCR assays has 100 % sensitivity. Genus identification by subsequent sequencing is possible for amplicons of the 18S PCR assay. In conclusion, combination of the two independent Mucorales assays described in this study, 18S and 28S, detected all clinical samples associated with proven Mucorales infection (n = 10). Reliable and specific identification of Mucorales is a prerequisite for successful antifungal therapy as these fungi show intrinsic resistance to voriconazole and caspofungin.
Probing Time-Dependent Molecular Dipoles on the Attosecond Time Scale
Neidel, Ch.; Klei, J.; Yang, C.-H.; Rouzée, A.; Vrakking, M. J. J.; Klünder, K.; Miranda, M.; Arnold, C. L.; Fordell, T.; L'Huillier, A.; Gisselbrecht, M.; Johnsson, P.; Dinh, M. P.; Suraud, E.; Reinhard, P.-G.; Despré, V.; Marques, M. A. L.; Lépine, F.
2013-07-01
Photoinduced molecular processes start with the interaction of the instantaneous electric field of the incident light with the electronic degrees of freedom. This early attosecond electronic motion impacts the fate of the photoinduced reactions. We report the first observation of attosecond time scale electron dynamics in a series of small- and medium-sized neutral molecules (N2, CO2, and C2H4), monitoring time-dependent variations of the parent molecular ion yield in the ionization by an attosecond pulse, and thereby probing the time-dependent dipole induced by a moderately strong near-infrared laser field. This approach can be generalized to other molecular species and may be regarded as a first example of molecular attosecond Stark spectroscopy.
EON: software for long time simulations of atomic scale systems
Chill, Samuel T.; Welborn, Matthew; Terrell, Rye; Zhang, Liang; Berthet, Jean-Claude; Pedersen, Andreas; Jónsson, Hannes; Henkelman, Graeme
2014-07-01
The EON software is designed for simulations of the state-to-state evolution of atomic scale systems over timescales greatly exceeding that of direct classical dynamics. States are defined as collections of atomic configurations from which a minimization of the potential energy gives the same inherent structure. The time evolution is assumed to be governed by rare events, where transitions between states are uncorrelated and infrequent compared with the timescale of atomic vibrations. Several methods for calculating the state-to-state evolution have been implemented in EON, including parallel replica dynamics, hyperdynamics and adaptive kinetic Monte Carlo. Global optimization methods, including simulated annealing, basin hopping and minima hopping are also implemented. The software has a client/server architecture where the computationally intensive evaluations of the interatomic interactions are calculated on the client-side and the state-to-state evolution is managed by the server. The client supports optimization for different computer architectures to maximize computational efficiency. The server is written in Python so that developers have access to the high-level functionality without delving into the computationally intensive components. Communication between the server and clients is abstracted so that calculations can be deployed on a single machine, clusters using a queuing system, large parallel computers using a message passing interface, or within a distributed computing environment. A generic interface to the evaluation of the interatomic interactions is defined so that empirical potentials, such as in LAMMPS, and density functional theory as implemented in VASP and GPAW can be used interchangeably. Examples are given to demonstrate the range of systems that can be modeled, including surface diffusion and island ripening of adsorbed atoms on metal surfaces, molecular diffusion on the surface of ice and global structural optimization of nanoparticles.
G. AZHAGUNILA,
2011-02-01
Full Text Available The main aim of this work is to develop a Dynamic Voltage Scaling (DVS algorithm for real- time system with resource constraints and the system thus developed is fault tolerant as well. The system is assumed to contain independent periodic tasks. Earliest Deadline Firstscheduling algorithm is considered in this. The algorithm helps in meeting the deadlines of all the tasks and also ensures that the total power consumption is minimized. The other objective is to develop a fault tolerant system. The proposed system is designed to handle hardware faults. Thus the proposed system is energy efficient and reliable.
Asymptotic self-similar solutions with a characteristic time-scale
Waxman, Eli
2010-01-01
For a wide variety of initial and boundary conditions, adiabatic one dimensional flows of an ideal gas approach self-similar behavior when the characteristic length scale over which the flow takes place, $R$, diverges or tends to zero. It is commonly assumed that self-similarity is approached since in the $R\\to\\infty(0)$ limit the flow becomes independent of any characteristic length or time scales. In this case the flow fields $f(r,t)$ must be of the form $f(r,t)=t^{\\alpha_f}F(r/R)$ with $R\\propto(\\pm t)^\\alpha$. We show that requiring the asymptotic flow to be independent only of characteristic length scales imply a more general form of self-similar solutions, $f(r,t)=R^{\\delta_f}F(r/R)$ with $\\dot{R}\\propto R^\\delta$, which includes the exponential ($\\delta=1$) solutions, $R\\propto e^{t/\\tau}$. We demonstrate that the latter, less restrictive, requirement is the physically relevant one by showing that the asymptotic behavior of accelerating blast-waves, driven by the release of energy at the center of a co...
Effects of demographic stochasticity on biological community assembly on evolutionary time scales
Murase, Yohsuke
2010-04-13
We study the effects of demographic stochasticity on the long-term dynamics of biological coevolution models of community assembly. The noise is induced in order to check the validity of deterministic population dynamics. While mutualistic communities show little dependence on the stochastic population fluctuations, predator-prey models show strong dependence on the stochasticity, indicating the relevance of the finiteness of the populations. For a predator-prey model, the noise causes drastic decreases in diversity and total population size. The communities that emerge under influence of the noise consist of species strongly coupled with each other and have stronger linear stability around the fixed-point populations than the corresponding noiseless model. The dynamics on evolutionary time scales for the predator-prey model are also altered by the noise. Approximate 1/f fluctuations are observed with noise, while 1/ f2 fluctuations are found for the model without demographic noise. © 2010 The American Physical Society.
Meluzín Tomáš
2011-12-01
Full Text Available Abstract In this article, the authors study the relevance of the market timing hypothesis of going public, which tends to explain the lower post-issue operating performance of Czech initial public offerings. The data collected under the conditions of the Czech capital market are compared with the performance of companies selected from the main European stock exchanges, when they decided to adopt the IPO strategy. Achieving the objective required an empirical survey that involved a collection of accounting data in companies that had completed an initial public offer in the Czech capital market. The data were evaluated by financial performance measures. The comparisons were made using descriptive statistical methods. The research results broaden and deepen the present understanding of the market timing hypothesis in companies going public, particularly in the Czech Republic.
A conceptual framework for time and space scale interactions in the climate system
Meehl, G.A. [National Center for Atmospheric Research (United States); Lukas, R. [University of Hawaii (United States); Kiladis, G.N. [NOAA Aeronomy Lab (United States); Weickmann, K.M. [NOAA Climate Diagnostics Center (United States); Matthews, A.J. [University of East Anglia, Norwich (United Kingdom); Wheeler, M. [Bureau of Meteorology Research Centre (Australia)
2001-07-01
Interactions involving various time and space scales, both within the tropics and between the tropics and midlatitudes, are ubiquitous in the climate system. We propose a conceptual framework for understanding such interactions whereby longer time scales and larger space scales set the base state for processes on shorter time scales and smaller space scales, which in turn have an influence back on the longer time scales and larger space scales in a continuum of process-related interactions. Though not intended to be comprehensive, we do cite examples from the literature to provide evidence for the validity of this framework. Decadal time scale base states of the coupled climate system set the context for the manifestation of interannual time scales (El Nino/Southern Oscillation, ENSO and tropospheric biennial oscillation, TBO) which are influenced by and interact with the annual cycle and seasonal time scales. Those base states in turn influence the large-scale coupled processes involved with intraseasonal and submonthly time scales, tied to interactions within the tropics and extratropics, and tropical-midlatitude teleconnections. All of these set the base state for processes on the synoptic and mesoscale and regional/local space scales. Events at those relatively short time scales and small space scales may then affect the longer time scale and larger space scale processes in turn, reaching back out to submonthly, intraseasonal, seasonal, annual, TBO, ENSO and decadal. Global coupled models can capture some elements of the decadal, ENSO, TBO, annual and seasonal time scales with the associated global space scales. However, coupled models are less successful at simulating phenomena at subseasonal and shorter time scales with hemispheric and smaller space scales. In the context of the proposed conceptual framework, the synergistic interactions of the time and space scales suggest that a high priority must be placed on improved simulations of all of the time and
Attractors of relaxation discrete-time systems with chaotic dynamics on a fast time scale
Maslennikov, Oleg V.; Nekorkin, Vladimir I. [Institute of Applied Physics of RAS, Nizhny Novgorod (Russian Federation)
2016-07-15
In this work, a new type of relaxation systems is considered. Their prominent feature is that they comprise two distinct epochs, one is slow regular motion and another is fast chaotic motion. Unlike traditionally studied slow-fast systems that have smooth manifolds of slow motions in the phase space and fast trajectories between them, in this new type one observes, apart the same geometric objects, areas of transient chaos. Alternating periods of slow regular motions and fast chaotic ones as well as transitions between them result in a specific chaotic attractor with chaos on a fast time scale. We formulate basic properties of such attractors in the framework of discrete-time systems and consider several examples. Finally, we provide an important application of such systems, the neuronal electrical activity in the form of chaotic spike-burst oscillations.
Attractors of relaxation discrete-time systems with chaotic dynamics on a fast time scale.
Maslennikov, Oleg V; Nekorkin, Vladimir I
2016-07-01
In this work, a new type of relaxation systems is considered. Their prominent feature is that they comprise two distinct epochs, one is slow regular motion and another is fast chaotic motion. Unlike traditionally studied slow-fast systems that have smooth manifolds of slow motions in the phase space and fast trajectories between them, in this new type one observes, apart the same geometric objects, areas of transient chaos. Alternating periods of slow regular motions and fast chaotic ones as well as transitions between them result in a specific chaotic attractor with chaos on a fast time scale. We formulate basic properties of such attractors in the framework of discrete-time systems and consider several examples. Finally, we provide an important application of such systems, the neuronal electrical activity in the form of chaotic spike-burst oscillations.
Asymptotic Expansions of Backward Equations for Two-time-scale Markov Chains in Continuous Time
G Yin; Dung Tien Nguyen
2009-01-01
This work develops asymptotic expansions for solutions of systems of backward equations of timeinhomogeneons Markov chains in continuous time. Owing to the rapid progress in technology and the increasing complexity in modeling, the underlying Markov chains often have large state spaces, which make the computational tasks infeasible. To reduce the complexity, two-time-scale formulations are used. By introducing a small parameter ε＞ 0 and using suitable decomposition and aggregation procedures, it is formulated as a singular perturbation problem. Both Markov chains having recurrent states only and Markov chains including also transient states are treated. Under certain weak irreducibility and smoothness conditions of the generators, the desired asymptotic expansions are constructed. Then error bounds are obtained.
Time-resolved and time-scale adaptive measures of spike train synchrony
Kreuz, Thomas; Greschner, Martin; Andrzejak, Ralph G
2010-01-01
A wide variety of approaches to estimate the degree of synchrony between two or more spike trains have been proposed. One of the most recent methods is the ISI-distance which extracts information from the interspike intervals (ISIs) by evaluating the ratio of the instantaneous firing rates. In contrast to most previously proposed measures it is parameter free and time-scale independent. However, it is not well suited to track changes in synchrony that are based on spike coincidences. Here we propose the SPIKE-distance, a complementary measure which is sensitive to spike coincidences but still shares the fundamental advantages of the ISI-distance. In particular, it is easy to visualize in a time-resolved manner and can be extended to a method that is also applicable to larger sets of spike trains. We show the merit of the SPIKE-distance using both simulated and real data.
Time-resolved and time-scale adaptive measures of spike train synchrony.
Kreuz, Thomas; Chicharro, Daniel; Greschner, Martin; Andrzejak, Ralph G
2011-01-30
A wide variety of approaches to estimate the degree of synchrony between two or more spike trains have been proposed. One of the most recent methods is the ISI-distance which extracts information from the interspike intervals (ISIs) by evaluating the ratio of the instantaneous firing rates. In contrast to most previously proposed measures it is parameter free and time-scale independent. However, it is not well suited to track changes in synchrony that are based on spike coincidences. Here we propose the SPIKE-distance, a complementary measure which is sensitive to spike coincidences but still shares the fundamental advantages of the ISI-distance. In particular, it is easy to visualize in a time-resolved manner and can be extended to a method that is also applicable to larger sets of spike trains. We show the merit of the SPIKE-distance using both simulated and real data. Copyright © 2010 Elsevier B.V. All rights reserved.
Noether theorem for nonholonomic nonconservative mechanical systems in phase space on time scales
Zu, Qi-hang; Zhu, Jian-qing
2016-08-01
The paper focuses on studying the Noether theorem for nonholonomic nonconservative mechanical systems in phase space on time scales. First, the Hamilton equations of nonholonomic nonconservative systems on time scales are established, which is based on the Lagrange equations for nonholonomic systems on time scales. Then, based upon the quasi-invariance of Hamilton action of systems under the infinitesimal transformations with respect to the time and generalized coordinate on time scale, the Noether identity and the conserved quantity of nonholonomic nonconservative systems on time scales are obtained. Finally, an example is presented to illustrate the application of the results.
Multiple time scales and the lifetime coefficient of variation: engineering applications.
Kordonsky, K B; Gertsbakh, I
1997-01-01
We consider linear combinations of "natural" time scales and choose the "best" one which provides the minimum coefficient of variation of the lifetime. Our time scale is in fact a generalized Miner time scale because the latter is based on an appropriate weighting of the times spent on low and high level loadings. The suggested modus operandi for finding the "best" time scale has many features in common with the approach suggested by Farewell and Cox (1979) and Oakes (1995) which is devoted to multiple time scales in survival analysis.
Two-phase micro- and macro-time scales in particle-laden turbulent channel flows
Bing Wang; Michael Manhart
2012-01-01
The micro- and macro-time scales in two-phase turbulent channel flows are investigated using the direct numerical simulation and the Lagrangian particle trajectory methods for the fluid- and the particle-phases,respectively.Lagrangian and Eulerian time scales of both phases are calculated using velocity correlation functions.Due to flow anisotropy,micro-time scales are not the same with the theoretical estimations in large Reynolds number (isotropic) turbulence.Lagrangian macro-time scales of particle-phase and of fluid-phase seen by particles are both dependent on particle Stokes number.The fluid-phase Lagrangian integral time scales increase with distance from the wall,longer than those time scales seen by particles.The Eulerian integral macro-time scales increase in near-wall regions but decrease in out-layer regions.The moving Eulerian time scales are also investigated and compared with Lagrangian integral time scales,and in good agreement with previous measurements and numerical predictions.For the fluid particles the micro Eulerian time scales are longer than the Lagrangian ones in the near wall regions,while away from the walls the micro Lagrangian time scales are longer.The Lagrangian integral time scales are longer than the Eulerian ones.The results are useful for further understanding two-phase flow physics and especially for constructing accurate prediction models of inertial particle dispersion.
Long Term Time Variability of Cosmic Rays and Possible Relevance to the Development of Life on Earth
Erlykin, A. D.; Wolfendale, A. W.
2010-07-01
An analysis is made of the manner in which the cosmic ray intensity at Earth has varied over its existence and its possible relevance to both the origin and the evolution of life. Much of the analysis relates to the `high energy’ cosmic rays ( E > 1014 eV; =0.1 PeV) and their variability due to the changing proximity of the solar system to supernova remnants which are generally believed to be responsible for most cosmic rays up to PeV energies. It is pointed out that, on a statistical basis, there will have been considerable variations in the likely 100 My between the Earth’s biosphere reaching reasonable stability and the onset of very elementary life. Interestingly, there is the increasingly strong possibility that PeV cosmic rays are responsible for the initiation of terrestrial lightning strokes and the possibility arises of considerable increases in the frequency of lightnings and thereby the formation of some of the complex molecules which are the `building blocks of life’. Attention is also given to the well known generation of the oxides of nitrogen by lightning strokes which are poisonous to animal life but helpful to plant growth; here, too, the violent swings of cosmic ray intensities may have had relevance to evolutionary changes. A particular variant of the cosmic ray acceleration model, put forward by us, predicts an increase in lightning rate in the past and this has been sought in Korean historical records. Finally, the time dependence of the overall cosmic ray intensity, which manifests itself mainly at sub-10 GeV energies, has been examined. The relevance of cosmic rays to the `global electrical circuit’ points to the importance of this concept.
Yang M. Guo
2015-01-01
Full Text Available Health trend prediction is critical to ensure the safe operation of highly reliable systems. However, complex systems often present complex dynamic behaviors and uncertainty, which makes it difficult to develop a precise physical prediction model. Therefore, time series is often used for prediction in this case. In this paper, in order to obtain better prediction accuracy in shorter computation time, we propose a new scheme which utilizes multiple relevant time series to enhance the completeness of the information and adopts a prediction model based on least squares support vector regression (LS-SVR to perform prediction. In the scheme, we apply two innovative ways to overcome the drawbacks of the reported approaches. One is to remove certain support vectors by measuring the linear correlation to increase sparseness of LS-SVR; the other one is to determine the linear combination weights of multiple kernels by calculating the root mean squared error of each basis kernel. The results of prediction experiments indicate preliminarily that the proposed method is an effective approach for its good prediction accuracy and low computation time, and it is a valuable method in applications.
Santos, Eugene, Jr.; Santos, Eunice E.; Santos, Eugene S.
2004-04-01
Given a massive and dynamic space of information (nuggets) and a query to be answered, how can the correct (answer) nuggets be retrieved in an effective and efficient manner? We present a large-scale distributed real-time architecture based on anytime intelligent foraging, gathering, and matching (I-FGM) on massive and dynamic information spaces. Simply put, we envision that when given a search query, large numbers of computational processes are alerted or activated in parallel to begin identifying and retrieving the appro-priate information nuggets. In particular, our approach aims to provide an anytime capa-bility which functions as follows: Given finite computational resources, I-FGM will pro-ceed to explore the information space and, over time, continuously identify and update promising candidate nugget, thus, good candidates will be available at anytime on re-quest. With the computational costs of evaluating the relevance of a candidate nugget, the anytime nature of I-FGM will provide increasing confidence on nugget selections over time by providing admissible partial evaluations. When a new promising candidate is identified, the current set of selected nuggets is re-evaluated and updated appropriately. Essentially, I-FGM will guide its finite computational resources in locating the target in-formation nuggets quickly and iteratively over time. In addition, the goal of I-FGM is to naturally handle new nuggets as they appear. A central element of our framework is to provide a formal computational model of this massive data-intensive problem.
V. Martinez-Quiroga
2014-01-01
Full Text Available System codes along with necessary nodalizations are valuable tools for thermal hydraulic safety analysis. Qualifying both codes and nodalizations is an essential step prior to their use in any significant study involving code calculations. Since most existing experimental data come from tests performed on the small scale, any qualification process must therefore address scale considerations. This paper describes the methodology developed at the Technical University of Catalonia in order to contribute to the qualification of Nuclear Power Plant nodalizations by means of scale disquisitions. The techniques that are presented include the so-called Kv-scaled calculation approach as well as the use of “hybrid nodalizations” and “scaled-up nodalizations.” These methods have revealed themselves to be very helpful in producing the required qualification and in promoting further improvements in nodalization. The paper explains both the concepts and the general guidelines of the method, while an accompanying paper will complete the presentation of the methodology as well as showing the results of the analysis of scaling discrepancies that appeared during the posttest simulations of PKL-LSTF counterpart tests performed on the PKL-III and ROSA-2 OECD/NEA Projects. Both articles together produce the complete description of the methodology that has been developed in the framework of the use of NPP nodalizations in the support to plant operation and control.
Favali, Paolo; Beranzoli, Laura; Best, Mairi; Franceschini, PierLuigi; Materia, Paola; Peppoloni, Silvia; Picard, John
2014-05-01
EMSO (European Multidisciplinary Seafloor and Water Column Observatory) is a large-scale European Research Infrastructure (RI). It is a geographically distributed infrastructure composed of several deep-seafloor and water-column observatories, which will be deployed at key sites in European waters, spanning from the Arctic, through the Atlantic and Mediterranean, to the Black Sea, with the basic scientific objective of real-time, long-term monitoring of environmental processes related to the interaction between the geosphere, biosphere and hydrosphere. EMSO is one of the environmental RIs on the ESFRI roadmap. The ESRFI Roadmap identifies new RIs of pan-European importance that correspond to the long term needs of European research communities. EMSO will be the sub-sea segment of the EU's large-scale Earth Observation program, Copernicus (previously known as GMES - Global Monitoring for Environment and Security) and will significantly enhance the observational capabilities of European member states. An open data policy compliant with the recommendations being developed within the GEOSS initiative (Global Earth Observation System of Systems) will allow for shared use of the infrastructure and the exchange of scientific information and knowledge. The processes that occur in the oceans have a direct impact on human societies, therefore it is crucial to improve our understanding of how they operate and interact. To encompass the breadth of these major processes, sustained and integrated observations are required that appreciate the interconnectedness of atmospheric, surface ocean, biological pump, deep-sea, and solid-Earth dynamics and that can address: • natural and anthropogenic change; • interactions between ecosystem services, biodiversity, biogeochemistry, physics, and climate; • impacts of exploration and extraction of energy, minerals, and living resources; • geo-hazard early warning capability for earthquakes, tsunamis, gas-hydrate release, and slope
Changes in channel morphology over human time scales [Chapter 32
John M. Buffington
2012-01-01
Rivers are exposed to changing environmental conditions over multiple spatial and temporal scales, with the imposed environmental conditions and response potential of the river modulated to varying degrees by human activity and our exploitation of natural resources. Watershed features that control river morphology include topography (valley slope and channel...
Mapping Playgrids for Learning across Space, Time, and Scale
Hollett, Ty; Kalir, Jeremiah H.
2017-01-01
In this article, we analyze the production of learner-generated playgrids. Playgrids are produced when learners knit together social media tools to participate across settings and scales, accomplish their goals, pursue interests, and make their learning more enjoyable and personally meaningful. Through case study methodology we examine how two…
Space-time modeling of catchment scale drought characteristics
Tallaksen, L.; Hisdal, H.; Lanen, van H.A.J.
2009-01-01
Drought may affect all components of the water cycle and covers commonly a large part of the catchment area. This paper examines drought propagation at the catchment scale using spatially aggregated drought characteristics and illustrates the importance of catchment processes in modifying the
Boese, W.T.; Ford, P.C. [Univ. of California, Santa Barbara, CA (United States)
1995-08-16
Intermediates relevant to the carbonylation of metal alkyl complexes have been generated by laser flash photolysis of the manganese acyl complexes RC(O)Mn(CO){sub 5} (R = CH{sub 3}, CD{sub 3}, CH{sub 2}CH{sub 3}, CH{sub 2}F, CF{sub 3}). This results in immediate CO photodissociation to give intermediate acyl complexes which were observed by time resolved infrared (TRIR) and time resolved optical (TRO) spectroscopy. In the presence of added ligands, such intermediates are trapped to form stable cis-substituted octahedral complexes in competition with alkyl migration from the acyl group to give the alkyl pentacarbonyl complexes RMn(CO){sub 5}. The spectra and reactivity of the intermediate (I) derived from CH{sub 3}C(O)Mn(CO){sub 5} (A) indicate that this exists as the chelated acyl complex ({eta}{sup 2}-CH{sub 3}CO)Mn(CO){sub 4} in weakly coordinating solvents such as cyclohexane but as the solvento species cis-CH{sub 3}C(O)Mn(CO){sub 4}(THF) in tetrahydrofuran. Comparisons with thermal reaction kinetics support the assertion that the intermediates generated photochemically are indeed relevant to understanding the mechanism for CH{sub 3}Mn(CO){sub 5} carbonylation. The CF{sub 3} and CH{sub 2}F analogs of I are much more reactive than I in cyclohexane solution, and this has been interpreted in terms of the {eta}{sup 2}-acyl configuration being destabilized by these electron-withdrawing groups. 33 refs., 10 figs., 4 tabs.
Input-output description of linear systems with multiple time-scales
Madriz, R. S.; Sastry, S. S.
1984-01-01
It is pointed out that the study of systems evolving at multiple time-scales is simplified by studying reduced-order models of these systems valid at specific time-scales. The present investigation is concerned with an extension of results on the time-scale decomposition of autonomous systems to that of input-output systems. The results are employed to study conditions under which positive realness of a transfer function is preserved under singular perturbation. Attention is given to the perturbation theory for linear operators, the multiple time-scale structure of autonomous linear systems, the input-output description of two time-scale linear systems, the positive realness of two time-scale systems, and multiple time-scale linear systems.
Investigation of cosmic rays in very short time scales
Peltonen, J.; Valtonen, E.; Torsti, J. J.; Arvela, H.; Lumme, M.; Nieminen, M.; Vainikka, E.
1985-01-01
A fast databuffer system, where cosmic ray events in the Turku hadron spectrometer, including particle arrival times are recorded with time resolution of 100 ns was constructed. The databuffer can be read continuously by a microprocessor, which preanalyzes the data and transfers it to the main computer. The time span, that can be analyzed in every detail, is a few seconds. The high time resolution enables a study of time correlated groups of high energy particles. In addition the operational characteristics of the spectrometer can be monitored in detail.
Grasping Deep Time with Scaled Space in Personal Environs
Jacobsen, B. H.
2014-01-01
Deep time comprises the deep past before written history all the way back to the Big Bang as well as the deep future from the time of our grandchildren and beyond the lifetime of our Sun. Numerous installations called time walks or geology paths have previously been designed to communicate...... of modern man, the age of dinosaurs ended at 650 m and the Big Bang is 137 km away. This choice obviously makes mental calculations easy, and all of time fits inside a geographical area of moderate size and so helps the citizen gain ownership to this learning tool and hence to time. The idea was tested...
Global terrestrial biogeochemistry: Perturbations, interactions, and time scales
Braswell, B.H. Jr.
1996-12-01
Global biogeochemical processes are being perturbed by human activity, principally that which is associated with industrial activity and expansion of urban and agricultural complexes. Perturbations have manifested themselves at least since the beginning of the 19th Century, and include emissions of CO{sub 2} and other pollutants from fossil fuel combustion, agricultural emissions of reactive nitrogen, and direct disruption of ecosystem function through land conversion. These perturbations yield local impacts, but there are also global consequences that are the sum of local-scale influences. Several approaches to understanding the global-scale implications of chemical perturbations to the Earth system are discussed. The lifetime of anthropogenic CO{sub 2} in the atmosphere is an important concept for understanding the current and future commitment to an altered atmospheric heat budget. The importance of the terrestrial biogeochemistry relative to the lifetime of excess CO{sub 2} is demonstrated using dynamic, aggregated models of the global carbon cycle.
Lyulin, Alexey V; Michels, M A J
2007-08-24
Molecular-dynamics simulation is used to explore the influence of thermal and mechanical history of typical glassy polymers on their deformation. Polymer stress-strain and energy-strain developments have been followed for different deformation velocities, also in closed extension-recompression loops. The latter simulate for the first time the experimentally observed mechanical rejuvenation and overaging of polymers, and energy partitioning reveals essential differences between mechanical and thermal rejuvenation. All results can be qualitatively interpreted by considering the ratios of the relevant time scales: for cooling down, for deformation, and for segmental relaxation.
Exploring large scale time-series data using nested timelines
Xie, Zaixian; Ward, Matthew O.; Rundensteiner, Elke A.
2013-01-01
When data analysts study time-series data, an important task is to discover how data patterns change over time. If the dataset is very large, this task becomes challenging. Researchers have developed many visualization techniques to help address this problem. However, little work has been done regarding the changes of multivariate patterns, such as linear trends and clusters, on time-series data. In this paper, we describe a set of history views to fill this gap. This technique works under two modes: merge and non-merge. For the merge mode, merge algorithms were applied to selected time windows to generate a change-based hierarchy. Contiguous time windows having similar patterns are merged first. Users can choose different levels of merging with the tradeoff between more details in the data and less visual clutter in the visualizations. In the non-merge mode, the framework can use natural hierarchical time units or one defined by domain experts to represent timelines. This can help users navigate across long time periods. Gridbased views were designed to provide a compact overview for the history data. In addition, MDS pattern starfields and distance maps were developed to enable users to quickly investigate the degree of pattern similarity among different time periods. The usability evaluation demonstrated that most participants could understand the concepts of the history views correctly and finished assigned tasks with a high accuracy and relatively fast response time.
Characteristic time-scales for macroscopic quantum tunneling
Ranfagni, A. [Istituto di Fisica Applicata ' Nello Carrara' , Consiglio Nazionale delle Ricerche, Via Panciatichi 64, 50127 Florence (Italy); Scuola di Specializzazione in Ottica dell' Universita di Firenze, Florence (Italy); Cacciari, I. [Scuola di Specializzazione in Ottica dell' Universita di Firenze, Florence (Italy); Sandri, P. [Scuola di Specializzazione in Ottica dell' Universita di Firenze, Florence (Italy); Ranfagni, C. [Facolta di Scienze Matematiche, Fisiche e Naturali, Corso di Laurea in Fisica dell' Universita di Firenze, Florence (Italy); Ruggeri, R. [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Sezione di Firenze, Florence (Italy)]. E-mail: r.ruggeri@ifac.cnr.it; Agresti, A. [Dipartimento di Fisica dell' Universita di Firenze, Florence (Italy)
2005-08-22
Tunneling time ({tau}{sub t}), in its real and imaginary parts, can be deduced from measurements of decay time ({tau}{sub d}) in Josephson junctions. It turns out that the real part of {tau}{sub t} is much shorter than the imaginary one, which can be identified with the semiclassical time. A third quantity is the Zeno-time ({tau}{sub Z}) which, in turn, can be estimated from the previous ones, since it is approximately given by their geometrical mean. The possibility of observing the Zeno-effect is then discussed.
Miller, Joshua D.; Price, Joanna; Campbell, W. Keith
2012-01-01
Some scholars have called for the replacement of the Narcissistic Personality Inventory (NPI) with more narrow scales measuring grandiosity and entitlement instead. In the current study, the authors examined the relations among the NPI and measures of grandiosity and entitlement, as well as in relation to a measure of the Five-Factor Model (FFM).…
Ortiz-Iniesta, Maria Jesus; Melian-Cabrera, Ignacio
2015-01-01
A mild template removal of microcrystalline beta zeolite, based on Fenton chemistry, was optimized. Fenton detemplation was studied in terms of applicability conditions window, reaction rate and scale up. TGA and CHN elemental analysis were used to evaluate the detemplation effectiveness, while 'CP,
Monteiro, PMS
2006-09-01
Full Text Available or mortality of rock lobster in the southern Benguela; Medium term (2 month) forecasting of the intensification of the remote forcing of ETSA derived LOW which has a bearing on the Namibian hake fishery These two scales are discussed in detail in the companion...
Miller, Joshua D.; Price, Joanna; Campbell, W. Keith
2012-01-01
Some scholars have called for the replacement of the Narcissistic Personality Inventory (NPI) with more narrow scales measuring grandiosity and entitlement instead. In the current study, the authors examined the relations among the NPI and measures of grandiosity and entitlement, as well as in relation to a measure of the Five-Factor Model (FFM).…
Pant, Jeevan K; Krishnan, Sridhar
2016-07-01
A new signal reconstruction algorithm for compressive sensing based on the minimization of a pseudonorm which promotes block-sparse structure on the first-order difference of the signal is proposed. Involved optimization is carried out by using a sequential version of Fletcher-Reeves' conjugate-gradient algorithm, and the line search is based on Banach's fixed-point theorem. The algorithm is suitable for the reconstruction of foot gait signals which admit block-sparse structure on the first-order difference. An additional algorithm for the estimation of stride-interval, swing-interval, and stance-interval time series from the reconstructed foot gait signals is also proposed. This algorithm is based on finding zero crossing indices of the foot gait signal and using the resulting indices for the computation of time series. Extensive simulation results demonstrate that the proposed signal reconstruction algorithm yields improved signal-to-noise ratio and requires significantly reduced computational effort relative to several competing algorithms over a wide range of compression ratio. For a compression ratio in the range from 88% to 94%, the proposed algorithm is found to offer improved accuracy for the estimation of clinically relevant time-series parameters, namely, the mean value, variance, and spectral index of stride-interval, stance-interval, and swing-interval time series, relative to its nearest competitor algorithm. The improvement in performance for compression ratio as high as 94% indicates that the proposed algorithms would be useful for designing compressive sensing-based systems for long-term telemonitoring of human gait signals.
Time Evolution of Galaxy Scaling Relations in Cosmological Simulations
Taylor, Philip
2016-01-01
We predict the evolution of galaxy scaling relationships from cosmological, hydrodynamical simulations, that reproduce the scaling relations of present-day galaxies. Although we do not assume co-evolution between galaxies and black holes a priori, we are able to reproduce the black hole mass--velocity dispersion relation. This relation does not evolve, and black holes actually grow along the relation from significantly less massive seeds than have previously been used. AGN feedback does not very much affect the chemical evolution of our galaxies. In our predictions, the stellar mass--metallicity relation does not change its shape, but the metallicity significantly increases from $z\\sim2$ to $z\\sim1$, while the gas-phase mass-metallicity relation does change shape, having a steeper slope at higher redshifts ($z\\lesssim3$). Furthermore, AGN feedback is required to reproduce observations of the most massive galaxies at $z\\lesssim1$, specifically their positions on the star formation main sequence and galaxy mass...
Implementation of Time-Scale Transformation Based on Continuous Wavelet Theory
无
2000-01-01
The basic objective of time-scale transformation is to compress or expand the signal in time field while keeping the same spectral properties.This paper presents two methods to derive time-scale transformation formula based on continuous wavelet transform.For an arbitrary given square-integrable function f(t),g(t) = f(t/λ) is derived by continuous wavelet transform and its inverse transform.The result shows that time-scale transformation may be obtained through the modification of the time-scale of wavelet function filter using equivalent substitution. The paper demonstrates the result by theoretic derivations and experimental simulation.
Weak microlensing effect and stability of pulsar time scale
Pshirkov, M S
2006-01-01
An influence of the weak microlensing effect on the pulsar timing is investigated for pulsar B1937+21. Average residuals of Time of Arrival (TOA) due to the effect would be as large as 10 ns in 20 years observation span. These residuals can be much greater (up to 1 ms in 20 years span) if pulsar is located in globular cluster (or behind it).
Time-scale invariance as an emergent property in a perceptron with realistic, noisy neurons
Buhusi, Catalin V.; Oprisan, Sorinel A.
2013-01-01
In most species, interval timing is time-scale invariant: errors in time estimation scale up linearly with the estimated duration. In mammals, time-scale invariance is ubiquitous over behavioral, lesion, and pharmacological manipulations. For example, dopaminergic drugs induce an immediate, whereas cholinergic drugs induce a gradual, scalar change in timing. Behavioral theories posit that time-scale invariance derives from particular computations, rules, or coding schemes. In contrast, we discuss a simple neural circuit, the perceptron, whose output neurons fire in a clockwise fashion (interval timing) based on the pattern of coincidental activation of its input neurons. We show numerically that time-scale invariance emerges spontaneously in a perceptron with realistic neurons, in the presence of noise. Under the assumption that dopaminergic drugs modulate the firing of input neurons, and that cholinergic drugs modulate the memory representation of the criterion time, we show that a perceptron with realistic neurons reproduces the pharmacological clock and memory patterns, and their time-scale invariance, in the presence of noise. These results suggest that rather than being a signature of higher-order cognitive processes or specific computations related to timing, time-scale invariance may spontaneously emerge in a massively-connected brain from the intrinsic noise of neurons and circuits, thus providing the simplest explanation for the ubiquity of scale invariance of interval timing. PMID:23518297
Wohlmuth, Johannes; Andersen, Jørgen Vitting
2006-05-01
We use agent-based models to study the competition among investors who use trading strategies with different amount of information and with different time scales. We find that mixing agents that trade on the same time scale but with different amount of information has a stabilizing impact on the large and extreme fluctuations of the market. Traders with the most information are found to be more likely to arbitrage traders who use less information in the decision making. On the other hand, introducing investors who act on two different time scales has a destabilizing effect on the large and extreme price movements, increasing the volatility of the market. Closeness in time scale used in the decision making is found to facilitate the creation of local trends. The larger the overlap in commonly shared information the more the traders in a mixed system with different time scales are found to profit from the presence of traders acting at another time scale than themselves.
Considering Time-Scale Requirements for the Future
2013-05-01
to correct for the annual seasonal variation in the Earth’s rotational speed and is rarely used today. 4 20 " 15 .. Equation of Time 0 0 I 10 ID...York, 1960. R. Coutrez, ’Transactions of the International Astronomical Union." Ciel et Terre , Vol. 73, 1957, pp. 472. S. Newcomb, Tables of the
Beach morphological variations over micro-time scales
Murty, C.S.; Veerayya, M.; Sastry, J.S.; Varadachari, V.V.R.
and down the beach face with breakers, locations of which alternately shift landward and seaward with the rise and fall of tide are observed. The ground water table shows an oscillation with tide with a time lag of about 1 hr. When the ground water table...
Perception of short time scale intervals in a hypnotic virtuoso
Noreika, Valdas; Falter, Christine M.; Arstila, Valtteri; Wearden, John H.; Kallio, Sakari
2012-01-01
Previous studies showed that hypnotized individuals underestimate temporal intervals in the range of several seconds to tens of minutes. However, no previous work has investigated whether duration perception is equally disorderly when shorter time intervals are probed. In this study, duration percep
Coherent spectroscopies on ultrashort time and length scales
Schneider C.
2013-03-01
Full Text Available Three spectroscopic techniques are presented that provide simultaneous spatial and temporal resolution: modified confocal microscopy with heterodyne detection, space-time-resolved spectroscopy using coherent control concepts, and coherent two-dimensional nano-spectroscopy. Latest experimental results are discussed.
Time Scales in the JPL and CfA Ephemerides
Standish, E. M.
1998-01-01
Over the past decades, the IAU has repeatedly attempted to correct its definition of the basic fundamental argument used in the emphemerides. Finally, they have defined a time system which is physically possible, according to the accepted standard theory of gravitation.
Perception of short time scale intervals in a hypnotic virtuoso
Noreika, Valdas; Falter, Christine M.; Arstila, Valtteri; Wearden, John H.; Kallio, Sakari
2012-01-01
Previous studies showed that hypnotized individuals underestimate temporal intervals in the range of several seconds to tens of minutes. However, no previous work has investigated whether duration perception is equally disorderly when shorter time intervals are probed. In this study, duration
Does expressive timing in music performance scale proportionally with tempo?
Desain, P.; Honing, H.
1994-01-01
Evidence is presented that expressive timing in music is not relationally invariant with global tempo. Our results stem from an analysis of repeated performances of Beethoven's variations on a Paisiello theme. Recordings were made of two pianists playing the pieces at three tempi. In contrast with t
Zouaoui, J; Trunfio-Sfarghiu, A M; Brizuela, L; Piednoir, A; Maniti, O; Munteanu, B; Mebarek, S; Girard-Egrot, A; Landoulsi, A; Granjon, T
2017-09-09
Considering the importance of cellular mechanics in the birth and evolution of cancer towards increasingly aggressive stages, we compared nano-mechanical properties of non-tumoral (WPMY-1) and highly aggressive metastatic (PC-3) prostate cell lines both on cell aggregates, single cells, and membrane lipids. Cell aggregate rheological properties were analyzed during dynamic compression stress performed on a homemade rheometer. Single cell visco-elasticity measurements were performed by Atomic Force Microscopy using a cantilever with round tip on surface-attached cells. At a molecular level, the lateral diffusion coefficient of total extracted lipids deposited as a Langmuir monolayer on an air-water interface was measured by the FRAP technique. At cellular pellet scale, and at single cell scale, PC-3 cells were less stiff, less viscous, and thus more prone to deformation than the WPMY-1 control. Interestingly, stress-relaxation curves indicated a two-step response, which we attributed to a differential response coming from two cell elements, successively stressed. Both responses are faster for PC-3 cells. At a molecular scale, the dynamics of the PC-3 lipid extracts are also faster than that of WPMY-1 lipid extracts. As the evolution of cancer towards increasingly aggressive stages is accompanied by alterations both in membrane composition and in cytoskeleton dynamical properties, we attribute differences in viscoelasticity between PC-3 and WPMY-1 cells to modifications of both elements. A decrease in stiffness and a less viscous behavior may be one of the diverse mechanisms that cancer cells adopt to cope with the various physiological conditions that they encounter. Copyright © 2017 Elsevier B.V. All rights reserved.
Rider, Raamses; Kelley-Baker, Tara; Voas, Robert B; Murphy, Bernard; McKnight, A James; Levings, Charles
2006-05-01
The Preventing Alcohol-Related Convictions (PARC) program is a novel educational curriculum for first-time DUI offenders, with the ultimate goal of reducing DUI recidivism. It differs from traditional DUI education and prevention programs in that it does not suggest to DUI offenders that they must abstain from alcohol entirely or control their drinking to prevent a future DUI; rather, it teaches students to prevent a future DUI by not driving their cars to drinking events. Thus, the emphasis of the curriculum is on controlling driving rather than controlling drinking to avoid future DUI convictions. The implementation of the program is ongoing throughout the state of Florida. The current randomized study focused on intermediate outcomes relevant for DUI recidivism; specifically, individuals' readiness for change regarding drinking and driving, and their endorsement of a PARC planning and action approach (controlling driving) versus a traditional approach (controlling drinking). The current research demonstrated that the PARC program is effective in moving participants toward more readiness for change and toward a strategy of planning ahead to avoid driving to any venue in which drinking may occur. Future research will assess the ultimate effect on DUI recidivism.
Klöckner, Wolf; Gacem, Riad; Anderlei, Tibor; Raven, Nicole; Schillberg, Stefan; Lattermann, Clemens; Büchs, Jochen
2013-12-02
Among disposable bioreactor systems, cylindrical orbitally shaken bioreactors show important advantages. They provide a well-defined hydrodynamic flow combined with excellent mixing and oxygen transfer for mammalian and plant cell cultivations. Since there is no known universal correlation between the volumetric mass transfer coefficient for oxygen kLa and relevant operating parameters in such bioreactor systems, the aim of this current study is to experimentally determine a universal kLa correlation. A Respiration Activity Monitoring System (RAMOS) was used to measure kLa values in cylindrical disposable shaken bioreactors and Buckingham's π-Theorem was applied to define a dimensionless equation for kLa. In this way, a scale- and volume-independent kLa correlation was developed and validated in bioreactors with volumes from 2 L to 200 L. The final correlation was used to calculate cultivation parameters at different scales to allow a sufficient oxygen supply of tobacco BY-2 cell suspension cultures. The resulting equation can be universally applied to calculate the mass transfer coefficient for any of seven relevant cultivation parameters such as the reactor diameter, the shaking frequency, the filling volume, the viscosity, the oxygen diffusion coefficient, the gravitational acceleration or the shaking diameter within an accuracy range of +/- 30%. To our knowledge, this is the first kLa correlation that has been defined and validated for the cited bioreactor system on a bench-to-pilot scale.
Strong light fields coax intramolecular reactions on femtosecond time scales
Krishnamurthy, M; Mathur, D
2004-01-01
Energetic H$_2^+$ ions are formed as a result of intra-molecular rearrangement during fragmentation of linear alcohols (methanol, ethanol, propanol, hexanol, and dodecanol) induced by intense optical fields produced by 100 fs long, infrared, laser pulses of peak intensity 8$\\times10^{15}$ W cm$^{-2}$. Polarization dependent measurements show, counterintuitively, that rearrangement is induced by the strong optical field within a single laser pulse, and that it occurs before Coulomb explosion of the field-ionized multiply charged alcohols.
Simultaneous storm time equatorward and poleward large-scale TIDs on a global scale
Habarulema, John Bosco; Katamzi, Zama Thobeka; Yizengaw, Endawoke; Yamazaki, Yosuke; Seemala, Gopi
2016-07-01
We report on the first simultaneous observations of poleward and equatorward traveling ionospheric disturbances (TIDs) during the same geomagnetic storm period on a global scale. While poleward propagating TIDs originate from the geomagnetic equator region, equatorward propagating TIDs are launched from the auroral regions. On a global scale, we use total electron content observations from the Global Navigation Satellite Systems to show that these TIDs existed over South American, African, and Asian sectors. The American and African sectors exhibited predominantly strong poleward TIDs, while the Asian sector recorded mostly equatorward TIDs which crossed the geomagnetic equator to either hemisphere on 9 March 2012. However, both poleward and equatorward TIDs are simultaneously present in all three sectors. Using a combination of ground-based magnetometer observations and available low-latitude radar (JULIA) data, we have established and confirmed that poleward TIDs of geomagnetic equator origin are due to ionospheric electrodynamics, specifically changes in E × B vertical drift after the storm onset.
Fei Yu
2009-01-01
Full Text Available Based on the theory of calculus on time scales, the homeomorphism theory, Lyapunov functional method, and some analysis techniques, sufficient conditions are obtained for the existence, uniqueness, and global exponential stability of the equilibrium point of Cohen-Grossberg bidirectional associative memory (BAM neural networks with distributed delays and impulses on time scales. This is the first time applying the time-scale calculus theory to unify the discrete-time and continuous-time Cohen-Grossberg BAM neural network with impulses under the same framework.
Statistics of bedload transport over steep slopes: Separation of time scales and collective motion
Heyman, J; Ma, H B; Ancey, C
2016-01-01
Steep slope streams show large fluctuations of sediment discharge across several time scales. These fluctuations may be inherent to the internal dynamics of the sediment transport process. A probabilistic framework thus seems appropriate to analyze such a process. In this letter, we present an experimental study of bedload transport over a steep slope flume for small to moderate Shields numbers. The sampling technique allows the acquisition of high-resolution time series of the solid discharge. The resolved time scales range from $10^{-2}$s up to $10^{5}$s. We show that two distinct time scales can be observed in the probability density function for the waiting time between moving particles. We make the point that the separation of time scales is related to collective dynamics. Proper statistics of a Markov process including collective entrainment are derived. The separation of time scales is recovered theoretically for low entrainment rates.
First-passage times in multi-scale random walks: the impact of movement scales on search efficiency
Campos, Daniel; Bartumeus, Frederic; Raposo, E. P.; Méndez, Vicenç
2015-01-01
An efficient searcher needs to balance properly the tradeoff between the exploration of new spatial areas and the exploitation of nearby resources, an idea which is at the core of scale-free L\\'evy search strategies. Here we study multi-scale random walks as an approximation to the scale- free case and derive the exact expressions for their mean-first passage times in a one-dimensional finite domain. This allows us to provide a complete analytical description of the dynamics driving the asymm...
Global and Local Color Time Scales to Encode Timeline Events in Ion Trajectories for Glassies
J. M. Sharif
2015-02-01
Full Text Available Glassy compounds lead directly to high ionic conductivity. Ionic conductivity generates ion trajectories. However, these trajectories have been represented by two-dimensional graph in order to visualize the timeline events in ion trajectories. This study addresses this problem by encoding the timeline events in ion trajectories with global and local color scales. Two time scales have been introduced namely Global Color Time Scale and Local Color Time Scale. The rainbow color has been chosen to represent global time scale meanwhile solid color has been used to generate local time scale. Based on evaluation, these techniques are successful in representing timeline events in ion trajectories for understanding the complicated heterogeneous movement of ion trajectories.
Continuous-wave laser particle conditioning: Thresholds and time scales
Brown, Andrew; Ogloza, Albert; Olson, Kyle; Talghader, Joseph
2017-03-01
The optical absorption of contaminants on high reflectivity mirrors was measured using photo thermal common-path interferometry before and after exposure to high power continuous-wave laser light. The contaminants were micron-sized graphite flakes on hafnia-silica distributed Bragg reflectors illuminated by a ytterbium-doped fiber laser. After one-second periods of exposure, the mirrors demonstrated reduced absorption for irradiances as low as 11 kW cm-2 and had an obvious threshold near 20 kW cm-2. Final absorption values were reduced by up to 90% of their initial value for irradiances of 92 kW cm-2. For shorter pulses at 34 kW cm-2, a minimum exposure time required to begin absorption reduction was found between 100 μs and 200 μs, with particles reaching their final minimum absorption value within 300 ms. Microscope images of the surface showed agglomerated particles fragmenting with some being removed completely, probably by evaporation for exposures between 200 μs to 10 ms. Exposures of 100 ms and longer left behind a thin semi-transparent residue, covering much of the conditioned area. An order of magnitude estimate of the time necessary to begin altering the surface contaminants (also known as "conditioning") indicates about 200 μs seconds at 34 kW cm-2, based on heating an average carbon particle to its sublimation temperature including energy loss to thermal contact and radiation. This estimation is close to the observed exposure time required to begin absorption reduction.
A Cool Business: Trapping Intermediates on the submillisecond time scale
Yeh, Syun-Ru
2004-03-01
The freeze-quenching technique is extremely useful for trapping meta-stable intermediates populated during fast chemical or biochemical reactions. The application of this technique, however, is limited by the long mixing time of conventional solution mixers and the slow freezing time of cryogenic fluids. To overcome these problems, we have designed and tested a novel microfluidic silicon mixer equipped with a new freeze-quenching device, with which reactions can be followed down to 50 microseconds. In the microfluidic silicon mixer, seven vertical pillars with 10 micrometer diameter are arranged perpendicular to the flow direction and in a staggered fashion in the 450 picoliter mixing chamber to enhance turbulent mixing. The mixed solution jet, with a cross-section of 10 micrometer by 100 micrometer, exits from the microfluidic silicon mixer with a linear flow velocity of 20 m/sec. It instantaneously freezes on one of two rotating copper wheels maintained at 77 K and is subsequently ground into an ultra-fine powder. The ultra-fine frozen powder exhibits excellent spectral quality, high packing factor and can be readily transferred between spectroscopic observation cells. The microfluidic mixer was tested by the reaction between azide and myoglobin at pH 5.0. It was found that complete mixing was achieved within the mixing dead-time of the mixer (20 microseconds) and the first observable point for this coupled device was determined to be 50 microseconds, which is approximately two orders of magnitude faster than commercially available instruments. Several new applications of this device in ultra-fast biological reactions will be presented. Acknowledgements: This work is done in collaboration with Dr. Denis Rousseau and is supported by the NIH Grants HL65465 to S.-R.Y. and GM67814 to D.L.R.
Pugh, C.E.
2001-01-29
Numerous large-scale fracture experiments have been performed over the past thirty years to advance fracture mechanics methodologies applicable to thick-wall pressure vessels. This report first identifies major factors important to nuclear reactor pressure vessel (RPV) integrity under pressurized thermal shock (PTS) conditions. It then covers 20 key experiments that have contributed to identifying fracture behavior of RPVs and to validating applicable assessment methodologies. The experiments are categorized according to four types of specimens: (1) cylindrical specimens, (2) pressurized vessels, (3) large plate specimens, and (4) thick beam specimens. These experiments were performed in laboratories in six different countries. This report serves as a summary of those experiments, and provides a guide to references for detailed information.
Bista, Iliana; Carvalho, Gary R.; Walsh, Kerry; Seymour, Mathew; Hajibabaei, Mehrdad; Lallias, Delphine; Christmas, Martin; Creer, Simon
2017-01-01
The use of environmental DNA (eDNA) in biodiversity assessments offers a step-change in sensitivity, throughput and simultaneous measures of ecosystem diversity and function. There remains, however, a need to examine eDNA persistence in the wild through simultaneous temporal measures of eDNA and biota. Here, we use metabarcoding of two markers of different lengths, derived from an annual time series of aqueous lake eDNA to examine temporal shifts in ecosystem biodiversity and in an ecologically important group of macroinvertebrates (Diptera: Chironomidae). The analyses allow different levels of detection and validation of taxon richness and community composition (β-diversity) through time, with shorter eDNA fragments dominating the eDNA community. Comparisons between eDNA, community DNA, taxonomy and UK species abundance data further show significant relationships between diversity estimates derived across the disparate methodologies. Our results reveal the temporal dynamics of eDNA and validate the utility of eDNA metabarcoding for tracking seasonal diversity at the ecosystem scale.
Toward the Optimal Configuration of Dynamic Voltage Scaling Points in Real-Time Applications
Hui-Zhan Yi; Xue-Jun Yang
2006-01-01
In real-time applications, compiler-directed dynamic voltage scaling (DVS) could reduce energy consumption efficiently, where compiler put voltage scaling points in the proper places, and the supply voltage and clock frequency were adjusted to the relationship between the reduced time and the reduced workload. This paper presents the optimal configuration of dynamic voltage scaling points without voltage scaling overhead, which minimizes energy consumption. The conclusion is proved theoretically. Finally, it is confirmed by simulations with equally-spaced voltage scaling configuration.
Geomagnetic Instability Time Scale 2008 (GITS-08) and dynamo processes
Singer, B. S.; Hoffman, K. A.
2008-12-01
During the past 2.6 million years Earth's outer core geodynamo has produced at least 18 geomagnetic excursions and 5 full polarity reversals. This record has been compiled from terrestrial volcanic rocks, including mainly basaltic lava flow sequences, but also two silicic ash beds, that have been analyzed using modern paleomagnetic techniques and dated using the 40Ar/39Ar method. Several brief periods of field instability associated with excursions correlate with lows in paleointensity or directional changes recorded in marine sediments, for example in the SINT2000 or GLOPIS75 composite records, or the more detailed records found at ODP site 919, that are dated using astronomically-forced oxygen isotope signals or ice layer counting. However, the lack of correlation of several excursions between marine and terrestrial records indicates that neither sediments, nor lava flows, are ideal recording media. Another factor complicating correlation is that some excursions may be geographically localized and not expressed globally. Despite decades of observation, these records remain fragmentary, especially when periods of millions of years are considered. Recent 40Ar/39Ar dating in our laboratory, that includes age determinations for the Mono Lake, Laschamp, Blake, Pringle Falls, Big Lost, West Eifel, and Agua Nova excursions, as well as the Halawa (C2r.2r-1) cryptochron, prompt us to critically review the terrestrial record of geodynamo instability and propose a GITS for the entire Quaternary period. Both the ca. 4:1 ratio of excursions to reversals during the past 2.6 Ma as well as the temporal pattern of occurrence of these events provide fundamental input as to the long-term behavior and, possibly, the structure of the core dynamo. On the one hand, intervals of significant temporal clustering of excursions have highlighted a relatively stable period of high field strength lasting >250 ka in the middle of the Brunhes chron during which time few, or no, excursions took
Loizu, Javier; Álvarez-Mozos, Jesús; Casalí, Javier; Goñi, Mikel
2015-04-01
Nowadays, most hydrological catchment models are designed to allow their use for streamflow simulation at different time-scales. While this permits models to be applied for broader purposes, it can also be a source of error in hydrological processes simulation at catchment scale. Those errors seem not to affect significantly simple conceptual models, but this flexibility may lead to large behavior errors in physically based models. Equations used in processes such as those related to soil moisture time-variation are usually representative at certain time-scales but they may not characterize properly water transfer in soil layers at larger scales. This effect is especially relevant as we move from detailed hourly scale to daily time-step, which are common time scales used at catchment streamflow simulation for different research and management practices purposes. This study aims to provide an objective methodology to identify the degree of similarity of optimal parameter values when hydrological catchment model calibration is developed at different time-scales. Thus, providing information for an informed discussion of physical parameter significance on hydrological models. In this research, we analyze the influence of time scale simulation on: 1) the optimal values of six highly sensitive parameters of the TOPLATS model and 2) the streamflow simulation efficiency, while optimization is carried out at different time scales. TOPLATS (TOPMODEL-based Land-Atmosphere Transfer Scheme) has been applied on its lumped version on three catchments of varying size located in northern Spain. The model has its basis on shallow groundwater gradients (related to local topography) that set up spatial patterns of soil moisture and are assumed to control infiltration and runoff during storm events and evaporation and drainage in between storm events. The model calculates the saturated portion of the catchment at each time step based on Topographical Index (TI) intervals. Surface
Kraucunas, Ian P.; Clarke, Leon E.; Dirks, James A.; Hathaway, John E.; Hejazi, Mohamad I.; Hibbard, Kathleen A.; Huang, Maoyi; Jin, Chunlian; Kintner-Meyer, Michael C.W.; Kleese van Dam, Kerstin; Leung, Lai-Yung R.; Li, Hongyi; Moss, Richard H.; Peterson, Marty J.; Rice, Jennie S.; Scott, Michael J.; Thomson, Allison M.; Voisin, Nathalie; West, Tristram O.
2015-04-01
The Platform for Regional Integrated Modeling and Analysis (PRIMA) is an innovative modeling system developed at Pacific Northwest National Laboratory (PNNL) to simulate interactions among natural and human systems at scales relevant to regional decision making. PRIMA brings together state-of-the-art models of regional climate, hydrology, agriculture, socioeconomics, and energy systems using a flexible coupling approach. The platform can be customized to inform a variety of complex questions and decisions, such as the integrated evaluation of mitigation and adaptation options across a range of sectors. Research into stakeholder decision support needs underpins the platform's application to regional issues, including uncertainty characterization. Ongoing numerical experiments are yielding new insights into the interactions among human and natural systems on regional scales with an initial focus on the energy-land-water nexus in the upper U.S. Midwest. This paper focuses on PRIMA’s functional capabilities and describes some lessons learned to date about integrated regional modeling.
Bryce, Donna; Bratzke, Daniel
2015-04-01
In this study, we investigated whether the method of time estimation plays a role in the apparent limits of introspection in dual-task processing. Previous studies showed that when participants reported introspective reaction times after each trial of a dual task by clicking on a visual analogue scale, they appeared to be unaware of the dual-task costs in their performance. However, visual analogue scales have seldom been used in interval estimation, and they may be inappropriate. In the present study, after each dual-task trial, participants reported their introspective reaction times either via a visual analogue scale or via the method of reproduction. The results replicated the previous findings, irrespective of method. That is, even though responses to the second task slowed down with increasing task overlap, this slowing was only very weakly reflected in the introspective reaction times. Thus, the participants' failure to report the objective dual-task costs in their reaction times is a rather robust finding that cannot be attributed to the method employed. However, introspective reaction times reported via visual analogue scales were more closely related to the objective reaction times, suggesting that visual analogue scales are preferable to reproduction. We conclude that introspective reaction times represent the same information regardless of method, but whether that information is temporal in nature is as yet unsettled.
RECENT GEODYNAMICS OF FAULT ZONES: FAULTING IN REAL TIME SCALE
Yu. O. Kuzmin
2015-09-01
Full Text Available Recent deformation processes taking place in real time are analyzed on the basis of data on fault zones which were collected by long-term detailed geodetic survey studies with application of field methods and satellite monitoring.A new category of recent crustal movements is described and termed as parametrically induced tectonic strain in fault zones. It is shown that in the fault zones located in seismically active and aseismic regions, super intensive displacements of the crust (5 to 7 cm per year, i.e. (5 to 7·10–5 per year occur due to very small external impacts of natural or technogenic / industrial origin.The spatial discreteness of anomalous deformation processes is established along the strike of the regional Rechitsky fault in the Pripyat basin. It is concluded that recent anomalous activity of the fault zones needs to be taken into account in defining regional regularities of geodynamic processes on the basis of real-time measurements.The paper presents results of analyses of data collected by long-term (20 to 50 years geodetic surveys in highly seismically active regions of Kopetdag, Kamchatka and California. It is evidenced by instrumental geodetic measurements of recent vertical and horizontal displacements in fault zones that deformations are ‘paradoxically’ deviating from the inherited movements of the past geological periods.In terms of the recent geodynamics, the ‘paradoxes’ of high and low strain velocities are related to a reliable empirical fact of the presence of extremely high local velocities of deformations in the fault zones (about 10–5 per year and above, which take place at the background of slow regional deformations which velocities are lower by the order of 2 to 3. Very low average annual velocities of horizontal deformation are recorded in the seismic regions of Kopetdag and Kamchatka and in the San Andreas fault zone; they amount to only 3 to 5 amplitudes of the earth tidal deformations per year.A
Modeling geomagnetic storms on prompt and diffusive time scales
Li, Zhao
The discovery of the Van Allen radiation belts in the 1958 was the first major discovery of the Space Age. There are two belts of energetic particles. The inner belt is very stable, but the outer belt is extremely variable, especially during geomagnetic storms. As the energetic particles are hazardous to spacecraft, understanding the source of these particles and their dynamic behavior driven by solar activity has great practical importance. In this thesis, the effects of magnetic storms on the evolution of the electron radiation belts, in particular the outer zone, is studied using two types of numerical simulation: radial diffusion and magnetohydrodynamics (MHD) test-particle simulation. A radial diffusion code has been developed at Dartmouth, applying satellite measurements to model flux as an outer boundary condition, exploring several options for the diffusion coefficient and electron loss time. Electron phase space density is analyzed for July 2004 coronal mass ejection (CME) driven storms and March-April 2008 co-rotating interaction region (CIR) driven storms, and compared with Global Positioning System (GPS) satellite measurements within 5 degrees of the magnetic equator at L=4.16. A case study of a month-long interval in the Van Allen Probes satellite era, March 2013, confirms that electron phase space density is well described by radial diffusion for the whole month at low first invariant 0.6 MeV by an order of magnitude over 24 hours as observed.
On the time scale associated with Monte Carlo simulations.
Bal, Kristof M; Neyts, Erik C
2014-11-28
Uniform-acceptance force-bias Monte Carlo (fbMC) methods have been shown to be a powerful technique to access longer timescales in atomistic simulations allowing, for example, phase transitions and growth. Recently, a new fbMC method, the time-stamped force-bias Monte Carlo (tfMC) method, was derived with inclusion of an estimated effective timescale; this timescale, however, does not seem able to explain some of the successes the method. In this contribution, we therefore explicitly quantify the effective timescale tfMC is able to access for a variety of systems, namely a simple single-particle, one-dimensional model system, the Lennard-Jones liquid, an adatom on the Cu(100) surface, a silicon crystal with point defects and a highly defected graphene sheet, in order to gain new insights into the mechanisms by which tfMC operates. It is found that considerable boosts, up to three orders of magnitude compared to molecular dynamics, can be achieved for solid state systems by lowering of the apparent activation barrier of occurring processes, while not requiring any system-specific input or modifications of the method. We furthermore address the pitfalls of using the method as a replacement or complement of molecular dynamics simulations, its ability to explicitly describe correct dynamics and reaction mechanisms, and the association of timescales to MC simulations in general.
On the time scale associated with Monte Carlo simulations
Bal, Kristof M., E-mail: kristof.bal@uantwerpen.be; Neyts, Erik C. [Department of Chemistry, University of Antwerp, Research Group PLASMANT, Universiteitsplein 1, 2610 Wilrijk, Antwerp (Belgium)
2014-11-28
Uniform-acceptance force-bias Monte Carlo (fbMC) methods have been shown to be a powerful technique to access longer timescales in atomistic simulations allowing, for example, phase transitions and growth. Recently, a new fbMC method, the time-stamped force-bias Monte Carlo (tfMC) method, was derived with inclusion of an estimated effective timescale; this timescale, however, does not seem able to explain some of the successes the method. In this contribution, we therefore explicitly quantify the effective timescale tfMC is able to access for a variety of systems, namely a simple single-particle, one-dimensional model system, the Lennard-Jones liquid, an adatom on the Cu(100) surface, a silicon crystal with point defects and a highly defected graphene sheet, in order to gain new insights into the mechanisms by which tfMC operates. It is found that considerable boosts, up to three orders of magnitude compared to molecular dynamics, can be achieved for solid state systems by lowering of the apparent activation barrier of occurring processes, while not requiring any system-specific input or modifications of the method. We furthermore address the pitfalls of using the method as a replacement or complement of molecular dynamics simulations, its ability to explicitly describe correct dynamics and reaction mechanisms, and the association of timescales to MC simulations in general.
Updating the planetary time scale: focus on Mars
Tanaka, Kenneth L.; Quantin-Nataf, Cathy
2013-01-01
Formal stratigraphic systems have been developed for the surface materials of the Moon, Mars, Mercury, and the Galilean satellite Ganymede. These systems are based on geologic mapping, which establishes relative ages of surfaces delineated by superposition, morphology, impact crater densities, and other relations and features. Referent units selected from the mapping determine time-stratigraphic bases and/or representative materials characteristic of events and periods for definition of chronologic units. Absolute ages of these units in some cases can be estimated using crater size-frequency data. For the Moon, the chronologic units and cratering record are calibrated by radiometric ages measured from samples collected from the lunar surface. Model ages for other cratered planetary surfaces are constructed primarily by estimating cratering rates relative to that of the Moon. Other cratered bodies with estimated surface ages include Venus and the Galilean satellites of Jupiter. New global geologic mapping and crater dating studies of Mars are resulting in more accurate and detailed reconstructions of its geologic history.
Time-scaled scenario of low-energy heavy-ion collisions
Iwata, Yoritaka
2013-01-01
The underlying scenario of low-energy heavy-ion collisions is presented based on time-dependent density-functional calculations. A classification of several types of reaction dynamics is given with respect to their time-scales.
Freshwater flushing time scales of the Vashishti Estuary, west coast of India
DineshKumar, P.K.; Sarma, R.V.; Zingde, M.D.
Results are presented for the Vashishti estuary, Kerala, India to evaluate its freshwater flushing time scales based on 8 sets of observations of longitudinal salinity distributions. The results of the flushing time using the fraction of freshwater...
Time and length scales within a fire and implications for numerical simulation
TIESZEN,SHELDON R.
2000-02-02
A partial non-dimensionalization of the Navier-Stokes equations is used to obtain order of magnitude estimates of the rate-controlling transport processes in the reacting portion of a fire plume as a function of length scale. Over continuum length scales, buoyant times scales vary as the square root of the length scale; advection time scales vary as the length scale, and diffusion time scales vary as the square of the length scale. Due to the variation with length scale, each process is dominant over a given range. The relationship of buoyancy and baroclinc vorticity generation is highlighted. For numerical simulation, first principles solution for fire problems is not possible with foreseeable computational hardware in the near future. Filtered transport equations with subgrid modeling will be required as two to three decades of length scale are captured by solution of discretized conservation equations. By whatever filtering process one employs, one must have humble expectations for the accuracy obtainable by numerical simulation for practical fire problems that contain important multi-physics/multi-length-scale coupling with up to 10 orders of magnitude in length scale.
Detecting abrupt climate changes on different time scales
Matyasovszky, István
2011-10-01
Two concepts are introduced for detecting abrupt climate changes. In the first case, the sampling frequency of climate data is high as compared to the frequency of climate events examined. The method is based on a separation of trend and noise in the data and is applicable to any dataset that satisfies some mild smoothness and statistical dependence conditions for the trend and the noise, respectively. We say that an abrupt change occurs when the first derivative of the trend function has a discontinuity and the task is to identify such points. The technique is applied to Northern Hemisphere temperature data from 1850 to 2009, Northern Hemisphere temperature data from proxy data, a.d. 200-1995 and Holocene δ18O values going back to 11,700 years BP. Several abrupt changes are detected that are, among other things, beneficial for determining the Medieval Warm Period, Little Ice Age and Holocene Climate Optimum. In the second case, the sampling frequency is low relative to the frequency of climate events studied. A typical example includes Dansgaard-Oeschger events. The methodology used here is based on a refinement of autoregressive conditional heteroscedastic models. The key element of this approach is the volatility that characterises the time-varying variance, and abrupt changes are defined by high volatilities. The technique applied to δ18O values going back to 122,950 years BP is suitable for identifying DO events. These two approaches for the two cases are closely related despite the fact that at first glance, they seem quite different.
Holder's and Hardy's Two Dimensional Diamond-alpha Inequalities on Time Scales
Ammi, Moulay Rchid Sidi
2010-01-01
We prove a two dimensional Holder and reverse-Holder inequality on time scales via the diamond-alpha integral. Other integral inequalities are established as well, which have as corollaries some recent proved Hardy-type inequalities on time scales.
Unique Existence Theorem of Solution of Almost Periodic Differential Equations on Time Scales
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.
Error estimates for asymptotic solutions of dynamic equations on time scales
Gro Hovhannisyan
2007-02-01
Full Text Available We establish error estimates for first-order linear systems of equations and linear second-order dynamic equations on time scales by using calculus on a time scales [1,4,5] and Birkhoff-Levinson's method of asymptotic solutions [3,6,8,9].
Zanardo, S.; Basu, N. B.; Rao, P. C.
2009-12-01
complex biogeochemistry of pesticides. We calibrated and validated the model against nitrate and atrazine data collected in the Little Vermillion River basin (~400 km2; Illinois, IN). Comparison with data showed an excellent agreement of the model outputs with the observed hydrographs and chemographs. The model was then used to explore the effect of time constants on biogeochemical signatures. Four time constants were used to characterize the coupling of hydrologic and biogeochemical processes considered in the model: 1) mean rainfall frequency; 2) mean residence time; 3) mass-transfer rate constant; 4) degradation rate constant. The effect of the four temporal constants on the hillslope biogeochemical response was explored through a sesnsitivity analyses. We hypothesize that a single dimensionless number, a combination of all four temporal constants, could explain the observed patterns. Because this dimensionless number embeds all of the relevant time scales, relative significance of the hydrologic and biogeochemical processes can be examined.
Frei, Heinz; Wasylenko, Walter; Frei, Heinz
2008-06-04
Time-resolved FT-IR spectra of carbon monoxide hydrogenation over alumina-supported ruthenium particles were recorded on themillisecond time scale at 700 K using pulsed release of CO and a continuous flow of H2/N2 (ratio 0.067 or 0.15, 1 atm total pressure). Adsorbed carbon monoxide was detected along with gas phase products methane (3016 and 1306 cm-1), water (1900 +- 1300 cm-1), and carbon dioxide (2348 cm-1). Aside from adsorbed CO, no other surface species were observed. The rate of formation of methane is 2.5 +- 0.4 s-1 and coincides with the rate of carbon dioxide growth (3.4 +- 0.6 s-1), thus indicating that CH4 and CO2 originate from a common intermediate. The broad band of adsorbed carbon monoxide has a maximum at 2010 cm-1 at early times (36 ms) that shifts gradually to 1960 cm-1 over a period of 3 s as a result of the decreasing surface concentration of CO. Kinetic analysis of the adsorbed carbon monoxide reveals that surface sites absorbing at the high frequency end of the infrared band are temporally linked to gas phase product growth. Specifically, a (linear) CO site at 2026 cm-1 decays with a rate constant of 2.9 +- 0.1 s-1, which coincides with the rise constant of CH4. This demonstrates that the linear CO site at 2026 cm-1 is the kinetically most relevant one for the rate-determining CO dissociation step under reaction conditions at 700 K.
Empirical study on structural properties in temporal networks under different time scales
Chen, Duanbing
2015-12-01
Many network analyzing methods are usually based on static networks. However, temporal networks should be considered so as to investigate real complex systems deeply since some dynamics on these systems cannot be described by static networks accurately. In this paper, four structural properties in temporal networks are empirically studied, including degree, clustering coefficient, adjacent correlation, and connected component. Three real temporal networks with different time scales are analyzed in this paper, including short message, telephone, and router networks. Moreover, structural properties of these temporal networks are compared with that of corresponding static aggregation networks in the whole time window. Some essential differences of structural properties between temporal and static networks are achieved through empirical analysis. Finally, the effect of structural properties on spreading dynamics under different time scales is investigated. Some interesting results such as turning point of structure evolving time scale corresponding to certain spreading dynamics time scale from the point of view of infected scale are achieved.
Ramkumar, Pavan; Fernandes, Hugo; Kording, Konrad; Segraves, Mark
2015-01-01
Like humans, monkeys make saccades nearly three times a second. To understand the factors guiding this frequent decision, computational models of vision attempt to predict fixation locations using bottom-up visual features and top-down goals. How do the relative influences of these factors evolve over multiple time scales? Here we analyzed visual features at fixations using a retinal transform that provides realistic visual acuity by suitably degrading visual information in the periphery. In a task in which monkeys searched for a Gabor target in natural scenes, we characterized the relative importance of bottom-up and task-relevant influences by decoding fixated from nonfixated image patches based on visual features. At fast time scales, we found that search strategies can vary over the course of a single trial, with locations of higher saliency, target-similarity, edge–energy, and orientedness looked at later on in the trial. At slow time scales, we found that search strategies can be refined over several weeks of practice, and the influence of target orientation was significant only in the latter of two search tasks. Critically, these results were not observed without applying the retinal transform. Our results suggest that saccade-guidance strategies become apparent only when models take into account degraded visual representation in the periphery. PMID:25814545
Linear-scaling computation of excited states in time-domain
YAM ChiYung; CHEN GuanHua
2014-01-01
The applicability of quantum mechanical methods is severely limited by their poor scaling.To circumvent the problem,linearscaling methods for quantum mechanical calculations had been developed.The physical basis of linear-scaling methods is the locality in quantum mechanics where the properties or observables of a system are weakly influenced by factors spatially far apart.Besides the substantial efforts spent on devising linear-scaling methods for ground state,there is also a growing interest in the development of linear-scaling methods for excited states.This review gives an overview of linear-scaling approaches for excited states solved in real time-domain.
Schuna, John M; Peterson, Courtney M; Thomas, Diana M; Heo, Moonseong; Hong, Sangmo; Choi, Woong; Heymsfield, Steven B
2015-01-01
Adult body mass (MB) empirically scales as height (Ht) squared (MB ∝ Ht(2) ), but does regional body mass and body composition as a whole also scale as Ht(2) ? This question is relevant to a wide range of biological topics, including interpretation of body mass index (BMI). Dual-energy X-ray absorptiometry (DXA) was used to quantify regional body mass [head (MH), trunk, arms, and legs] and whole-body composition [fat, lean soft tissue (LST), and bone mineral content (BMC)] in non-Hispanic (NH) white, NH black, Mexican American, and Korean adults participating in the National Health and Nutrition Examination Survey (NHANES; n = 17,126) and Korean NHANES (n = 8,942). Regression models were developed to establish Ht scaling powers for each measured component with adjustments for age and adiposity. Exploratory analyses revealed a consistent scaling pattern across men and women of the four population groups: regional mass powers, head (∼0.8-1) body composition, LST (∼2.0-2.3) body mass scaled uniformly across the eight sex and population groups as Ht(∼2) , tall and short subjects differed in body shape (e.g., MH/MB ∝ Ht(-∼1) ) and composition. Adult human body shape and relative composition are a function of body size as represented by stature, a finding that reveals a previously unrecognized phenotypic heterogeneity as defined by BMI. These observations provide new pathways for exploring mechanisms governing the interrelations between adult stature, body morphology, biomechanics, and metabolism. © 2014 Wiley Periodicals, Inc.
G V R Prasad
2009-11-01
This paper presents a brief review of recent advances in the classification of mammals at higher levels using fossils and molecular clocks. It also discusses latest fossil discoveries from the Cretaceous – Eocene (66–55 m.y.) rocks of India and their relevance to our current understanding of placental mammal origins and diversifications.
From clinically relevant outcome measures to quality of life in epilepsy : A time trade-off study
de Kinderen, Reina J A; Wijnen, Ben F M; van Breukelen, Gerard; Postulart, Debby; Majoie, Marian H J M; Aldenkamp, Albert P; Evers, Silvia M A A
2016-01-01
OBJECTIVES: A proposed method for bridging the gap between clinically relevant epilepsy outcome measures and quality-adjusted life years is to derive utility scores for epilepsy health states. The aim of this study is to develop such a utility-function and to investigate the impact of the epilepsy o
A short-time scale colloidal system reveals early bacterial adhesion dynamics.
Christophe Beloin
2008-07-01
Full Text Available The development of bacteria on abiotic surfaces has important public health and sanitary consequences. However, despite several decades of study of bacterial adhesion to inert surfaces, the biophysical mechanisms governing this process remain poorly understood, due, in particular, to the lack of methodologies covering the appropriate time scale. Using micrometric colloidal surface particles and flow cytometry analysis, we developed a rapid multiparametric approach to studying early events in adhesion of the bacterium Escherichia coli. This approach simultaneously describes the kinetics and amplitude of early steps in adhesion, changes in physicochemical surface properties within the first few seconds of adhesion, and the self-association state of attached and free-floating cells. Examination of the role of three well-characterized E. coli surface adhesion factors upon attachment to colloidal surfaces--curli fimbriae, F-conjugative pilus, and Ag43 adhesin--showed clear-cut differences in the very initial phases of surface colonization for cell-bearing surface structures, all known to promote biofilm development. Our multiparametric analysis revealed a correlation in the adhesion phase with cell-to-cell aggregation properties and demonstrated that this phenomenon amplified surface colonization once initial cell-surface attachment was achieved. Monitoring of real-time physico-chemical particle surface properties showed that surface-active molecules of bacterial origin quickly modified surface properties, providing new insight into the intricate relations connecting abiotic surface physicochemical properties and bacterial adhesion. Hence, the biophysical analytical method described here provides a new and relevant approach to quantitatively and kinetically investigating bacterial adhesion and biofilm development.
Estimating the flood frequency distribution at seasonal and annual time scales
E. Baratti
2012-12-01
Full Text Available We propose an original approach to infer the flood frequency distribution at seasonal and annual time scale. Our purpose is to estimate the peak flow that is expected for an assigned return period T, independently of the season in which it occurs (i.e. annual flood frequency regime, as well as in different selected sub-yearly periods (i.e. seasonal flood frequency regime. While a huge literature exists on annual flood frequency analysis, few studies have focused on the estimation of seasonal flood frequencies despite the relevance of the issue, for instance when scheduling along the months of the year the construction phases of river engineering works directly interacting with the active river bed, like for instance dams. An approximate method for joint frequency analysis is presented here that guarantees consistency between fitted annual and seasonal distributions, i.e. the annual cumulative distribution is the product of the seasonal cumulative distribution functions, under the assumption of independence among floods in different seasons. In our method the parameters of the seasonal frequency distributions are fitted by maximising an objective function that accounts for the likelihoods of both seasonal and annual peaks. In contrast to previous studies, our procedure is conceived to allow the users to introduce subjective weights to the components of the objective function in order to emphasize the fitting of specific seasons or of the annual peak flow distribution. An application to the time series of the Blue Nile daily flows at the Sudan–Ethiopia border is presented.
Multi-time scale analysis of precipitation variation in Guyuan,China:1957-2005
无
2008-01-01
Morlet wavelet transformation is used in this paper to analyze the multi-time scale characteristics of precipitation data series from 1957 to 2005 in Guyuan region.The results showed that (1) the annual precipitation evolution process had obvious multi-time scale variation characteristics of 15-25 years,7-12 years and 3-6 years,and different time scales had different oscillation energy densities;(2) the periods at smaller time scales changed more frequently,which often nested in a biggish quasi periodic oscillations,so the concrete time domain should be analyzed if necessary;(3) the precipitation had three main periods (22-year,9-year and 4-year) and the 22-year period was especially outstanding,and the analysis of this main period reveals that the precipitation would be in a relative high water period until about 2012.
Super-transient scaling in time-delay autonomous Boolean network motifs
D'Huys, Otti; Lohmann, Johannes; Haynes, Nicholas D.; Gauthier, Daniel J.
2016-09-01
Autonomous Boolean networks are commonly used to model the dynamics of gene regulatory networks and allow for the prediction of stable dynamical attractors. However, most models do not account for time delays along the network links and noise, which are crucial features of real biological systems. Concentrating on two paradigmatic motifs, the toggle switch and the repressilator, we develop an experimental testbed that explicitly includes both inter-node time delays and noise using digital logic elements on field-programmable gate arrays. We observe transients that last millions to billions of characteristic time scales and scale exponentially with the amount of time delays between nodes, a phenomenon known as super-transient scaling. We develop a hybrid model that includes time delays along network links and allows for stochastic variation in the delays. Using this model, we explain the observed super-transient scaling of both motifs and recreate the experimentally measured transient distributions.
Scaling Behavior of the First Arrival Time of a Random-Walking Magnetic Domain
Im, M.-Y.; Lee, S.-H.; Kim, D.-H.; Fischer, P.; Shin, S.-C.
2008-02-04
We report a universal scaling behavior of the first arrival time of a traveling magnetic domain wall into a finite space-time observation window of a magneto-optical microscope enabling direct visualization of a Barkhausen avalanche in real time. The first arrival time of the traveling magnetic domain wall exhibits a nontrivial fluctuation and its statistical distribution is described by universal power-law scaling with scaling exponents of 1.34 {+-} 0.07 for CoCr and CoCrPt films, despite their quite different domain evolution patterns. Numerical simulation of the first arrival time with an assumption that the magnetic domain wall traveled as a random walker well matches our experimentally observed scaling behavior, providing an experimental support for the random-walking model of traveling magnetic domain walls.
Super-transient scaling in time-delay autonomous Boolean network motifs.
D'Huys, Otti; Lohmann, Johannes; Haynes, Nicholas D; Gauthier, Daniel J
2016-09-01
Autonomous Boolean networks are commonly used to model the dynamics of gene regulatory networks and allow for the prediction of stable dynamical attractors. However, most models do not account for time delays along the network links and noise, which are crucial features of real biological systems. Concentrating on two paradigmatic motifs, the toggle switch and the repressilator, we develop an experimental testbed that explicitly includes both inter-node time delays and noise using digital logic elements on field-programmable gate arrays. We observe transients that last millions to billions of characteristic time scales and scale exponentially with the amount of time delays between nodes, a phenomenon known as super-transient scaling. We develop a hybrid model that includes time delays along network links and allows for stochastic variation in the delays. Using this model, we explain the observed super-transient scaling of both motifs and recreate the experimentally measured transient distributions.
A wavelet based approach to measure and manage contagion at different time scales
Berger, Theo
2015-10-01
We decompose financial return series of US stocks into different time scales with respect to different market regimes. First, we examine dependence structure of decomposed financial return series and analyze the impact of the current financial crisis on contagion and changing interdependencies as well as upper and lower tail dependence for different time scales. Second, we demonstrate to which extent the information of different time scales can be used in the context of portfolio management. As a result, minimizing the variance of short-run noise outperforms a portfolio that minimizes the variance of the return series.
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.
SHAO Li-wei; LIAO Xiao-zhong; ZHANG Yu-he
2007-01-01
Active disturbance rejection controller (ADRC) has good performance in induction motor (IM) control system, but controller parameter is difficult to tune. A method of tuning ADRC parameter by time scale is analyzed. The IM time scale is obtained by theoretical analysis. Combining the relations between scale time and ADRC parameters, ADRC parameter tuning in IM vector control based stator flux oriented is obtained. This parameter tuning method is validated by simulations and it provides a new technique for tuning of ADRC parameters of IM.
A simple scaling for the minimum instability time-scale of two widely spaced planets
Veras, Dimitri
2013-01-01
Long-term instability in multi-planet exosystems is a crucial consideration when confirming putative candidates, analyzing exoplanet populations, constraining the age of exosystems, and identifying the sources of white dwarf pollution. Two planets which are Hill stable are separated by a wide-enough distance to ensure that they will never collide. However, Hill stable planetary systems may eventually manifest Lagrange instability when the outer planet escapes or the inner planet collides with the star. We show empirically that for two nearly coplanar Hill stable planets with eccentricities less than about 0.3, instability can manifest itself only after a time corresponding to X initial orbits of the inner planet, where log_{10}(X) is of the order of 5.2 mu^{-0.18} and mu is the planet-star mass ratio measured in (Jupiter mass/Solar mass). This relation applies to any type of equal-mass secondaries, and suggests that two low-eccentricity Hill stable terrestrial-mass or smaller-mass planets should be Lagrange s...
A time-scale analysis of systematic risk: wavelet-based approach
Khalfaoui Rabeh, K; Boutahar Mohamed, B
2011-01-01
The paper studies the impact of different time-scales on the market risk of individual stock market returns and of a given portfolio in Paris Stock Market by applying the wavelet analysis. To investigate the scaling properties of stock market returns and the lead/lag relationship between them at different scales, wavelet variance and crosscorrelations analyses are used. According to wavelet variance, stock returns exhibit long memory dynamics. The wavelet cross-correlation analysis shows that...
Separation of time-scales and model reduction for stochastic reaction networks
Kang, Hye-Won
2010-01-01
A stochastic model for a chemical reaction network is embedded in a one-parameter family of models with species numbers and rate constants scaled by powers of the parameter. A systematic approach is developed for determining appropriate choices of the exponents that can be applied to large complex networks. When the scaling implies subnetworks have different time-scales, the subnetworks can be approximated separately providing insight into the behavior of the full network through the analysis of these lower dimensional approximations.
Hangx, Suzanne; Cordonnier, Benoît; Pijnenburg, Ronald; Renard, François; Spiers, Christopher
2017-04-01
Relating macroscopic deformation of granular media to grain-scale processes, such as grain fracturing, has been a focus of many studies. Understanding these processes is key for predicting surface subsidence and induced seismicity caused by hydrocarbon depletion, the hydraulic fracturing response of geothermal reservoirs, and post-seismic crustal deformation. With the development of state-of-the-art techniques, such as time-lapse X-ray tomography imaging during triaxial deformation, new avenues to investigate the operating mechanisms have opened up. As a first step to understanding grain-scale deformation processes, we performed a deformation experiment on highly porous sandstone, obtained from a depleting gas reservoir, using a novel small-scale triaxial deformation apparatus coupled to high-resolution 4D X-ray tomography, available at the European Synchrotron Radiation Facility (ESRF, Grenoble) and Université Grenoble Alpes. This state-of-the-art apparatus allows for 3D time-lapse imaging of samples, while deforming at pressure, temperature and fluid flow conditions relevant for geological reservoirs. We performed our experiment at relevant in-situ reservoir conditions (T = 100˚ C, 10 MPa pore pressure, 40 MPa effective confining pressure). Axial stress was increased step-wise until failure occurred, while continuously imaging deformation. This enables us to monitor progressive grain failure, and strain localisation, during deformation in real-time. Though the vast amount of data obtained from even a single test poses challenges for data analysis, this presentation will address the first results obtained from this experiment.
Estimating the distribution of rest-frame time-scales for blazar jets: a statistical approach
Liodakis, I.; Blinov, D.; Papadakis, I.; Pavlidou, V.
2017-03-01
In any flux-density limited sample of blazars, the distribution of the time-scale modulation factor Δt΄/Δt, which quantifies the change in observed time-scales compared to the rest-frame ones due to redshift and relativistic compression follows an exponential distribution with a mean depending on the flux limit of the sample. In this work, we produce the mathematical formalism that allows us to use this information in order to uncover the underlining rest-frame probability density function of measurable time-scales of blazar jets. We extensively test our proposed methodology using a simulated Flat Spectrum Radio Quasar population with a 1.5 Jy flux-density limit in the simple case (where all blazars share the same intrinsic time-scale), in order to identify limits of applicability and potential biases due to observational systematics and sample selection. We find that for monitoring with time intervals between observations longer than ∼30 per cent of the intrinsic time-scale under investigation the method loses its ability to produce robust results. For time intervals of ∼3 per cent of the intrinsic time-scale, the error of the method is as low as 1 per cent in recovering the intrinsic rest-frame time-scale. We applied our method to rotations of the optical polarization angle of blazars observed by RoboPol. We found that the intrinsic time-scales of the longest duration rotation event in each blazar follows a narrow distribution, well described by a normal distribution with mean 87 d and standard deviation 5 d. We discuss possible interpretations of this result.
Mastering Uncertainty and Risk at Multiple Time Scales in the Future Electrical Grid
Chertkov, Michael [Los Alamos National Laboratory; Bent, Russell W. [Los Alamos National Laboratory; Backhaus, Scott N. [Los Alamos National Laboratory
2012-07-10
Today's electrical grids enjoy a relatively clean separation of spatio-temporal scales yielding a compartmentalization of grid design, optimization, control and risk assessment allowing for the use of conventional mathematical tools within each area. In contrast, the future grid will incorporate time-intermittent renewable generation, operate via faster electrical markets, and tap the latent control capability at finer grid modeling scales; creating a fundamentally new set of couplings across spatiotemporal scales and requiring revolutionary advances in mathematics techniques to bridge these scales. One example is found in decade-scale grid expansion planning in which today's algorithms assume accurate load forecasts and well-controlled generation. Incorporating intermittent renewable generation creates fluctuating network flows at the hourly time scale, inherently linking the ability of a transmission line to deliver electrical power to hourly operational decisions. New operations-based planning algorithms are required, creating new mathematical challenges. Spatio-temporal scales are also crossed when the future grid's minute-scale fluctuations in network flows (due to intermittent generation) create a disordered state upon which second-scale transient grid dynamics propagate effectively invalidating today's on-line dynamic stability analyses. Addressing this challenge requires new on-line algorithms that use large data streams from new grid sensing technologies to physically aggregate across many spatial scales to create responsive, data-driven dynamic models. Here, we sketch the mathematical foundations of these problems and potential solutions.
Principles of 5D modeling, full integration of 3D space, time and scale
Van Oosterom, P.; Stoter, J.
2012-01-01
This paper proposes an approach for data modelling in five dimensions. Apart from three dimensions for geometrical representation and a fourth dimension for time, we identify scale as fifth dimensional characteristic. Considering scale as an extra dimension of geographic information, fully integrate
Multi-Scale Gaussian Processes: a Novel Model for Chaotic Time Series Prediction
ZHOU Ya-Tong; ZHANG Tai-Yi; SUN Jian-Cheng
2007-01-01
@@ Based on the classical Gaussian process (GP) model, we propose a multi-scale Gaussian process (MGP) model to predict the existence of chaotic time series. The MGP employs a covariance function that is constructed by a scaling function with its different dilations and translations, ensuring that the optimal hyperparameter is easy to determine.
Time scales of porphyry Cu deposit formation: insights from titanium diffusion in quartz
Mercer, Celestine N.; Reed, Mark H.; Mercer, Cameron M.
2015-01-01
Porphyry dikes and hydrothermal veins from the porphyry Cu-Mo deposit at Butte, Montana, contain multiple generations of quartz that are distinct in scanning electron microscope-cathodoluminescence (SEM-CL) images and in Ti concentrations. A comparison of microprobe trace element profiles and maps to SEM-CL images shows that the concentration of Ti in quartz correlates positively with CL brightness but Al, K, and Fe do not. After calibrating CL brightness in relation to Ti concentration, we use the brightness gradient between different quartz generations as a proxy for Ti gradients that we model to determine time scales of quartz formation and cooling. Model results indicate that time scales of porphyry magma residence are ~1,000s of years and time scales from porphyry quartz phenocryst rim formation to porphyry dike injection and cooling are ~10s of years. Time scales for the formation and cooling of various generations of hydrothermal vein quartz range from 10s to 10,000s of years. These time scales are considerably shorter than the ~0.6 m.y. overall time frame for each porphyry-style mineralization pulse determined from isotopic studies at Butte, Montana. Simple heat conduction models provide a temporal reference point to compare chemical diffusion time scales, and we find that they support short dike and vein formation time scales. We interpret these relatively short time scales to indicate that the Butte porphyry deposit formed by short-lived episodes of hydrofracturing, dike injection, and vein formation, each with discrete thermal pulses, which repeated over the ~3 m.y. generation of the deposit.
Pütz, Martin; Nielaba, Peter
2016-08-01
We report the influence of the strength of heat bath coupling on the demixing behavior in spinodal decomposing one component liquid-vapor systems. The smoothed particle hydrodynamics (SPH) method with a van der Waals equation of state is used for the simulation. A thermostat for SPH is introduced that is based on the Berendsen thermostat. It controls the strength of heat bath coupling and allows for quenches with exponential temperature decay at a certain thermalization time scale. The present method allows us to bridge several orders of magnitude in the thermalization time scale. The early stage is highly affected by the choice of time scale. A transition from exponential growth to a 1 /2 ordinary power law scaling in the characteristic lengths is observed. At high initial temperatures the growth is logarithmic. The comparison with pure thermal simulations reveals latent heat to raise the mean system temperature. Large thermalization time scales and thermal conductivity are figured out to affect a stagnation of heating, which is explained with convective processes. Furthermore, large thermalization time scales are responsible for a stagnation of growth of domains, which is temporally embedded between early and late stage of phase separation. Therefore, it is considered as an intermediate stage. We present an aspect concerning this stage, namely that choosing larger thermalization time scales increases the duration. Moreover, it is observed that diffuse interfaces are formed during this stage, provided that the stage is apparent. We show that the differences in the evolution between pure thermal simulations and simulations with an instantaneously scaled mean temperature can be explained by the thermalization process, since a variation of the time scale allows for the bridging between these cases of limit.
A Small-Scale, Feasibility Study of Academic Language Time in Primary Grade Language Arts
Roskos, Kathleen A.; Zuzolo, Nicole; Primm, Ashley
2017-01-01
A small-scale feasibility study was conducted to explore the implementation of academic language time (ALT) in primary grade classrooms with and without access to digital devices. Academic language time is a structural change that dedicates a portion of language arts instructional time to direct vocabulary instruction using evidence-based…
Design of turbulent tangential micro-mixers that mix liquids on the nanosecond time scale
Mitic, Sandra; Nieuwkasteele, van Jan W.; Berg, van den Albert; Vries, de Simon
2015-01-01
Unravelling (bio)chemical reaction mechanisms and macromolecular folding pathways on the (sub)microsecond time scale is limited by the time resolution of kinetic instruments for mixing reactants and observation of the progress of the reaction. To improve the mixing time resolution, turbulent four- a
Driving forces of Indian summer monsoon on Milankovitch and sub-Milankovitch time scales: A review
Naidu, P.D.
and deep water circulation changes drive the variability of southwest (SW) monsoon in the Indian subcontinent. Different forcing factors act on different time scales. Arabian Sea sediments consist of distinct fauna that are endemic to areas of upwelling...
A Study on Time-Scales Ratio and Turbulent Prandtl Number in Ducts of Industrial Applications
Rokni, Masoud
2006-01-01
This investigation concerns numerical time-scales ratio and turbulent Prandtl number in fully developed turbulent ﬂows in ducts of various cross-sections. The low Reynolds number version of a non-linear eddy viscosity model is proposed to predict the Reynolds stresses and the temperature ﬁeld...... is solved using a two-equation heat ﬂux model. The computed results compare satisfactory with the available experimental data. The time-scale ratio R is deﬁned as the ratio between the dynamic time-scale (k/ε) and the scalar time-scale(0.5θθ/εθ). Based on existing DNS data and calculations in this work...
Oscillation Criteria for Fourth-Order Nonlinear Dynamic Equations on Time Scales
Xin Wu
2013-01-01
Full Text Available We establish some new oscillation criteria for nonlinear dynamic equation of the form on an arbitrary time scale with , where are positive rd-continuous functions. An example illustrating the importance of our result is included.
Y. Kawada
2007-10-01
Full Text Available We investigate the time-scale invariant changes in electromagnetic and mechanical energy releases prior to a rock failure or a large earthquake. The energy release processes are caused by damage evolutions such as crack propagation, motion of charged dislocation, area-enlargement of sheared asperities and repetitive creep-rate changes. Damage mechanics can be used to represent the time-scale invariant evolutions of both brittle and plastic damages. Irreversible thermodynamics applied to the damage mechanics reveals that the damage evolution produces the variations in charge, dipole and electromagnetic signals in addition to mechanical energy release, and yields the time-scale invariant patterns of Benioff electromagnetic radiation and cumulative Benioff strain-release. The irreversible thermodynamic framework of damage mechanics is also applicable to the seismo-magnetic effect, and the time-scale invariance is recognized in the remanent magnetization change associated with damage evolution prior to a rock failure.
Multiple time scales in modeling the incidence of infections acquired in intensive care units
Martin Wolkewitz
2016-09-01
Full Text Available Abstract Background When patients are admitted to an intensive care unit (ICU their risk of getting an infection will be highly depend on the length of stay at-risk in the ICU. In addition, risk of infection is likely to vary over calendar time as a result of fluctuations in the prevalence of the pathogen on the ward. Hence risk of infection is expected to depend on two time scales (time in ICU and calendar time as well as competing events (discharge or death and their spatial location. The purpose of this paper is to develop and apply appropriate statistical models for the risk of ICU-acquired infection accounting for multiple time scales, competing risks and the spatial clustering of the data. Methods A multi-center data base from a Spanish surveillance network was used to study the occurrence of an infection due to Methicillin-resistant Staphylococcus aureus (MRSA. The analysis included 84,843 patient admissions between January 2006 and December 2011 from 81 ICUs. Stratified Cox models were used to study multiple time scales while accounting for spatial clustering of the data (patients within ICUs and for death or discharge as competing events for MRSA infection. Results Both time scales, time in ICU and calendar time, are highly associated with the MRSA hazard rate and cumulative risk. When using only one basic time scale, the interpretation and magnitude of several patient-individual risk factors differed. Risk factors concerning the severity of illness were more pronounced when using only calendar time. These differences disappeared when using both time scales simultaneously. Conclusions The time-dependent dynamics of infections is complex and should be studied with models allowing for multiple time scales. For patient individual risk-factors we recommend stratified Cox regression models for competing events with ICU time as the basic time scale and calendar time as a covariate. The inclusion of calendar time and stratification by ICU
LI Hong; L(U) Shu; ZHONG Shou-ming
2005-01-01
The global uniform asymptotic stability of competitive neural networks with different time scales and delay is investigated. By the method of variation of parameters and the method of inequality analysis, the condition for global uniformly asymptotically stable are given. A strict Lyapunov function for the flow of a competitive neural system with different time scales and delay is presented. Based on the function, the global uniform asymptotic stability of the equilibrium point can be proved.
Zhu, Ye; Wang, Wen; Singh, Vijay P; Liu, Yi
2016-11-15
Prediction of hydrological drought in the absence of hydrological records is of great significance for water resources management and risk assessment. In this study, two meteorological drought indices, including standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI) calculated at different time scales (1 to 12months), were analyzed for their capabilities in detecting hydrological droughts. The predictive skills of meteorological drought indices were assessed through correlation analysis, and two skill scores, i.e. probability of detection (POD) and false alarm rate (FAR). When used independently, indices of short time scales generally performed better than did those of long time scales. However, at least 31% of hydrological droughts were still missed in view of the peak POD score (0.69) of a single meteorological drought index. Considering the distinguished roles of different time scales in explaining hydrological droughts with disparate features, an optimization approach of blending SPI/SPEI at multiple time scales was proposed. To examine the robustness of the proposed method, data of 1964-1990 was used to establish the multiscalar index, then validate during 2000-2010. Results showed that POD exhibited a significant increase when more than two time scales were used, and the best performances were found when blending 8 time scales of SPI and 9 for SPEI, with the corresponding values of 0.82 and 0.85 for POD, 0.205 and 0.21 for FAR, in the calibration period, and even better performance in the validation period. These results far exceeded the performance of any single meteorological drought index. This suggests that when there is lack of streamflow measurements, blending climatic information of multiple time scales to jointly monitor hydrological droughts could be an alternative solution. Copyright © 2016 Elsevier B.V. All rights reserved.
Oscillation of Second-order Nonlinear Dynamic Equation on Time Scales
YANG Jia-shan
2013-01-01
The oscillation for a class of second order nonlinear variable delay dynamic equation on time scales with nonlinear neutral term and damping term was discussed in this article.By using the generalized Riccati technique,integral averaging technique and the time scales theory,some new sufficient conditions for oscillation of the equation are proposed.These results generalize and extend many known results for second order dynamic equations.Some examples are given to illustrate the main results of this article.
REGION QUALITATIVE ANALYSIS OF PREDATOR-PREY SYSTEMS ON TIME SCALES
无
2008-01-01
We first investigate some basic properties of dynamic equations on time scales,and propose contained curves to describe the jump direction of the discrete points.Then we perform qualitative analysis regarding the planar predator-prey systems on time scales,thereby obtain two theorems of this system.At last,we emulate application examples to discuss the parameters of the system.
Kawada, Y.; H. Nagahama; Nakamura, N.
2007-01-01
International audience; We investigate the time-scale invariant changes in electromagnetic and mechanical energy releases prior to a rock failure or a large earthquake. The energy release processes are caused by damage evolutions such as crack propagation, motion of charged dislocation, area-enlargement of sheared asperities and repetitive creep-rate changes. Damage mechanics can be used to represent the time-scale invariant evolutions of both brittle and plastic damages. Irreversible thermod...
A two-time-scale autopilot for high-performance aircraft
Menon, P. K. A.; Chatterji, G. B.; Cheng, V. H. L.
1991-01-01
A two-time-scale autopilot is proposed for the Aircraft Controls Design Challenge problem. This control law uses a nonlinear aircraft model constructed from the given vehicle simulation. The vehicle model is partitioned into slow translational dynamics and fast rotational dynamics. Feedback linearization is then employed to synthesize control laws for these two-time scales. Due to the nature of the synthesis, the control law is suitable for automatic trajectory following, and also for pilot control.
Wietsma, T. W.; Zhang, C.; Oostrom, M.; Grate, J. W.
2010-12-01
Capture and sequestration of anthropogenic CO2 in depleted oil and gas reservoirs, unminable coal seams and deep saline aquifer are being intensively studied as a promising strategy to mitigate CO2 emission into the atmosphere. Two critical research areas are trapping mechanisms and caprock sealing efficiency, which are controlled by interfacial processes at the fluid-fluid and fluid-rock interfaces. Fundamental understanding of capillary/viscous effects and host rock heterogeneity on trapping mechanisms and sealing efficiency can be gained through micromodel pore-scale displacement experiments. Experimental capabilities are being developed at the Environmental Molecular Sciences Lab (EMSL), Pacific Northwest National Laboratory (PNNL) to study coupled flow and reactive transport processes in complex systems at the pore-scale at relevant storage pressures and temperatures. This presentation highlights our strategies for design and construction of a unique high-pressure system for micromodel experimentation and a capability for visualizing dynamic interfacial processes using a solvatochromic dye under supercritical conditions. Preliminary results on displacement of brine by supercritical CO2 will be presented.
Poiata, N.; Satriano, C.; Vilotte, J. P.; Bernard, P.; Obara, K.
2015-12-01
Seismic radiation associated with transient deformations along the faults and subduction interfaces encompasses a variety of events, i.e., tectonic tremors, low-frequency earthquakes (LFE), very low-frequency earthquakes (VLFs), and slow-slip events (SSE), with a wide range of seismic moment and characteristic durations. Characterizing in space and time the complex sources of these slow earthquakes, and their relationship with background seismicity and large earthquakes generation, is of great importance for understanding the physics and mechanics of the processes of active deformations along the plate interfaces. We present here first developments towards a methodology for: (1) extracting the different frequency and scale components of observed tectonic tremor signal, using advanced time-frequency and time-scale signal representation such as Gabor transform scheme based on, e.g. Wilson bases or Modified Discrete Cosine Transform (MDCT) bases; (2) reconstructing their corresponding potential sources in space and time, using the array method of Poiata et al. (2015). The methodology is assessed using a dataset of tectonic tremor episodes from Shikoku, Japan, recorded by the Hi-net seismic network operated by NIED. We illustrate its performance and potential in providing activity maps - associated to different scale-components of tectonic tremors - that can be analyzed statistically to improve our understanding of tremor sources and scaling, as well as their relation with the background seismicity.
Multiple time-space scale atmosphere-ocean interactions and improvement of Zebiak-Cane model
钱维宏; 王绍武
1997-01-01
In a real climate system there are multiple time-space scale atmosphere-ocean interactions, ranging from the planetary scale and basin scale to local air-sea interactions. The Zebiak-Cane (ZC) model with one-level atmosphere described only local air-sea interaction process. Thus the planetary scale Hadley cell and Walker cell anomalies should be introduced in the model. Including the planetary scale Hadley cell anomaly in the model improved the prediction skill. It showed that the improved model provided satisfactory prediction of the equatorial eastern Pacific SST anomaly with lead time of 9-10 months not only for 1970-1991 but also for 1992-1995.
Small-time Scale Network Traffic Prediction Based on Complex-valued Neural Network
Yang, Bin
2017-07-01
Accurate models play an important role in capturing the significant characteristics of the network traffic, analyzing the network dynamic, and improving the forecasting accuracy for system dynamics. In this study, complex-valued neural network (CVNN) model is proposed to further improve the accuracy of small-time scale network traffic forecasting. Artificial bee colony (ABC) algorithm is proposed to optimize the complex-valued and real-valued parameters of CVNN model. Small-scale traffic measurements data namely the TCP traffic data is used to test the performance of CVNN model. Experimental results reveal that CVNN model forecasts the small-time scale network traffic measurement data very accurately
A hybrid procedure for MSW generation forecasting at multiple time scales in Xiamen City, China
Xu, Lilai, E-mail: llxu@iue.ac.cn [Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021 (China); Xiamen Key Lab of Urban Metabolism, Xiamen 361021 (China); Gao, Peiqing, E-mail: peiqing15@yahoo.com.cn [Xiamen City Appearance and Environmental Sanitation Management Office, 51 Hexiangxi Road, Xiamen 361004 (China); Cui, Shenghui, E-mail: shcui@iue.ac.cn [Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799 Jimei Road, Xiamen 361021 (China); Xiamen Key Lab of Urban Metabolism, Xiamen 361021 (China); Liu, Chun, E-mail: xmhwlc@yahoo.com.cn [Xiamen City Appearance and Environmental Sanitation Management Office, 51 Hexiangxi Road, Xiamen 361004 (China)
2013-06-15
Highlights: ► We propose a hybrid model that combines seasonal SARIMA model and grey system theory. ► The model is robust at multiple time scales with the anticipated accuracy. ► At month-scale, the SARIMA model shows good representation for monthly MSW generation. ► At medium-term time scale, grey relational analysis could yield the MSW generation. ► At long-term time scale, GM (1, 1) provides a basic scenario of MSW generation. - Abstract: Accurate forecasting of municipal solid waste (MSW) generation is crucial and fundamental for the planning, operation and optimization of any MSW management system. Comprehensive information on waste generation for month-scale, medium-term and long-term time scales is especially needed, considering the necessity of MSW management upgrade facing many developing countries. Several existing models are available but of little use in forecasting MSW generation at multiple time scales. The goal of this study is to propose a hybrid model that combines the seasonal autoregressive integrated moving average (SARIMA) model and grey system theory to forecast MSW generation at multiple time scales without needing to consider other variables such as demographics and socioeconomic factors. To demonstrate its applicability, a case study of Xiamen City, China was performed. Results show that the model is robust enough to fit and forecast seasonal and annual dynamics of MSW generation at month-scale, medium- and long-term time scales with the desired accuracy. In the month-scale, MSW generation in Xiamen City will peak at 132.2 thousand tonnes in July 2015 – 1.5 times the volume in July 2010. In the medium term, annual MSW generation will increase to 1518.1 thousand tonnes by 2015 at an average growth rate of 10%. In the long term, a large volume of MSW will be output annually and will increase to 2486.3 thousand tonnes by 2020 – 2.5 times the value for 2010. The hybrid model proposed in this paper can enable decision makers to
Integral Length and Time Scales of Velocity, Heat and Mass At and Near a Turbulent Free Surface
Curtis, G. M.; Zappa, C. J.; Variano, E. A.
2010-12-01
variation in integral length scales enabled the effective identification of periods of heavy turbulent mixing at the surface and revealed the localized nature of such events. Analogous to the integral length scale, the integral time scale analysis revealed the characteristic duration of turbulent events at the surface. Covariance and cospectra quantify the time and length scales that are most relevant to fluxes. The measurements presented here will increase our understanding of turbulent transport across the air-sea interface.
Universality and extremal aging for dynamics of spin glasses on sub-exponential time scales
Arous, G Ben
2010-01-01
We consider Random Hopping Time (RHT) dynamics of the Sherrington - Kirkpatrick (SK) model and p-spin models of spin glasses. For any of these models and for any inverse temperature we prove that, on time scales that are sub-exponential in the dimension, the properly scaled clock process (time-change process) of the dynamics converges to an extremal process. Moreover, on these time scales, the system exhibits aging like behavior which we called extremal aging. In other words, the dynamics of these models ages as the random energy model (REM) does. Hence, by extension, this confirms Bouchaud's REM-like trap model as a universal aging mechanism for a wide range of systems which, for the first time, includes the SK model.
Universal space-time scaling symmetry in the dynamics of bosons across a quantum phase transition
Clark, Logan W; Chin, Cheng
2016-01-01
The dynamics of many-body systems spanning condensed matter, cosmology, and beyond is hypothesized to be universal when the systems cross continuous phase transitions. The universal dynamics is expected to satisfy a scaling symmetry of space and time with the crossing rate, inspired by the Kibble-Zurek mechanism. We test this symmetry based on Bose condensates in a shaken optical lattice. Shaking the lattice drives condensates across an effectively ferromagnetic quantum phase transition. After crossing the critical point, the condensates manifest delayed growth of spin fluctuations and develop anti-ferromagnetic spatial correlations resulting from sub-Poisson generation of topological defects. The characteristic times and lengths scale as power-laws of the crossing rate, yielding the temporal exponent 0.50(2) and the spatial exponent 0.26(2), consistent with theory. Furthermore, the fluctuations and correlations are invariant in scaled space-time coordinates, in support of the scaling symmetry of quantum crit...
Vea, Isabelle M; Grimaldi, David A
2016-03-22
The radiation of flowering plants in the mid-Cretaceous transformed landscapes and is widely believed to have fuelled the radiations of major groups of phytophagous insects. An excellent group to test this assertion is the scale insects (Coccomorpha: Hemiptera), with some 8,000 described Recent species and probably the most diverse fossil record of any phytophagous insect group preserved in amber. We used here a total-evidence approach (by tip-dating) employing 174 morphological characters of 73 Recent and 43 fossil taxa (48 families) and DNA sequences of three gene regions, to obtain divergence time estimates and compare the chronology of the most diverse lineage of scale insects, the neococcoid families, with the timing of the main angiosperm radiation. An estimated origin of the Coccomorpha occurred at the beginning of the Triassic, about 245 Ma [228-273], and of the neococcoids 60 million years later [210-165 Ma]. A total-evidence approach allows the integration of extinct scale insects into a phylogenetic framework, resulting in slightly younger median estimates than analyses using Recent taxa, calibrated with fossil ages only. From these estimates, we hypothesise that most major lineages of coccoids shifted from gymnosperms onto angiosperms when the latter became diverse and abundant in the mid- to Late Cretaceous.
A multi-time scale approach to remaining useful life prediction in rolling bearing
Qian, Yuning; Yan, Ruqiang; Gao, Robert X.
2017-01-01
This paper presents a novel multi-time scale approach to bearing defect tracking and remaining useful life (RUL) prediction, which integrates enhanced phase space warping (PSW) with a modified Paris crack growth model. As a data-driven method, PSW describes the dynamical behavior of the bearing being tested on a fast-time scale, whereas the Paris crack growth model, as a physics-based model, characterizes the bearing's defect propagation on a slow-time scale. Theoretically, PSW constructs a tracking metric by evaluating the phase space trajectory warping of the bearing vibration data, and establishes a correlation between measurement on a fast-time scale and defect growth variables on a slow-time scale. Furthermore, PSW is enhanced by a multi-dimensional auto-regression (AR) model for improved accuracy in defect tracking. Also, the Paris crack growth model is modified by a time-piecewise algorithm for real-time RUL prediction. Case studies performed on two run-to-failure experiments indicate that the developed technique is effective in tracking the evolution of bearing defects and accurately predict the bearing RUL, thus contributing to the literature of bearing prognosis .
Sarlis, N. V.; Christopoulos, S.-R. G.; Bemplidaki, M. M.
2015-01-01
The entropy S in natural time as well as the entropy in natural time under time reversal S- have already found useful applications in the physics of complex systems, e.g., in the analysis of electrocardiograms (ECGs). Here, we focus on the complexity measures Λl which result upon considering how the statistics of the time series Δ S≤ft[\\equiv S- S-\\right] changes upon varying the scale l. These scale-specific measures are ratios of the standard deviations σ(Δ S_l) and hence independent of the mean value and the standard deviation of the data. They focus on the different dynamics that appear on different scales. For this reason, they can be considered complementary to other standard measures of heart rate variability in ECG, like SDNN, as well as other complexity measures already defined in natural time. An application to the analysis of ECG —when solely using NN intervals— is presented: We show how Λl can be used to separate ECG of healthy individuals from those suffering from congestive heart failure and sudden cardiac death.
Martin, Stephanie L.-O.; Carek, Andrew M.; Kim, Chang-Sei; Ashouri, Hazar; Inan, Omer T.; Hahn, Jin-Oh; Mukkamala, Ramakrishna
2016-12-01
Pulse transit time (PTT) is being widely pursued for cuff-less blood pressure (BP) monitoring. Most efforts have employed the time delay between ECG and finger photoplethysmography (PPG) waveforms as a convenient surrogate of PTT. However, these conventional pulse arrival time (PAT) measurements include the pre-ejection period (PEP) and the time delay through small, muscular arteries and may thus be an unreliable marker of BP. We assessed a bathroom weighing scale-like system for convenient measurement of ballistocardiography and foot PPG waveforms – and thus PTT through larger, more elastic arteries – in terms of its ability to improve tracking of BP in individual subjects. We measured “scale PTT”, conventional PAT, and cuff BP in humans during interventions that increased BP but changed PEP and smooth muscle contraction differently. Scale PTT tracked the diastolic BP changes well, with correlation coefficient of ‑0.80 ± 0.02 (mean ± SE) and root-mean-squared-error of 7.6 ± 0.5 mmHg after a best-case calibration. Conventional PAT was significantly inferior in tracking these changes, with correlation coefficient of ‑0.60 ± 0.04 and root-mean-squared-error of 14.6 ± 1.5 mmHg (p < 0.05). Scale PTT also tracked the systolic BP changes better than conventional PAT but not to an acceptable level. With further development, scale PTT may permit reliable, convenient measurement of BP.
Velten, Andreas
2017-05-01
Light scattering is a primary obstacle to optical imaging in a variety of different environments and across many size and time scales. Scattering complicates imaging on large scales when imaging through the atmosphere when imaging from airborne or space borne platforms, through marine fog, or through fog and dust in vehicle navigation, for example in self driving cars. On smaller scales, scattering is the major obstacle when imaging through human tissue in biomedical applications. Despite the large variety of participating materials and size scales, light transport in all these environments is usually described with very similar scattering models that are defined by the same small set of parameters, including scattering and absorption length and phase function. We attempt a study of scattering and methods of imaging through scattering across different scales and media, particularly with respect to the use of time of flight information. We can show that using time of flight, in addition to spatial information, provides distinct advantages in scattering environments. By performing a comparative study of scattering across scales and media, we are able to suggest scale models for scattering environments to aid lab research. We also can transfer knowledge and methodology between different fields.
Ford, R. M.
2010-12-01
Many processes contribute to the transport of microorganisms in groundwater environments. One process of interest is chemotaxis, whereby motile bacteria are able to detect and swim toward increasing concentrations of industrial hydrocarbons that they perceive as food sources. By enabling bacteria to migrate to the sources of pollutants that they degrade, chemotaxis has the potential to enhance bioremediation efforts, especially in less permeable zones where contamination may persist. To determine the field conditions under which chemotaxis might be exploited in a bioremediation scheme requires an understanding of the characteristic time scales in the system. We defined a dimensionless chemotaxis number that compares the time over which a bacterial population is exposed to a chemical gradient to the time required for a bacterial population to migrate a significant distance in response to a chemical gradient. The exposure time and the response time are dependent upon the experimental conditions and properties of the bacteria and chemical attractant. Experimental data was analyzed for a range of groundwater flow rates over a wide scope of experimental systems including a single-pore with NAPL source, a microfluidic channel with and without a porous matrix, a laboratory column, a bench-scale microcosm and a field-scale study. Chemical gradients were created transverse to the flow direction. Distributions of chemotactic and nonchemotactic bacteria were compared to determine the extent of migration due to chemotaxis. Under some conditions at higher flow rates, the effect of chemotaxis was diminished to the point of not being detected. The goal of the study was to determine a critical value for the dimensionless chemotaxis number (which is independent of scale) that can be used as a design criterion to ascertain a priori the conditions under which a chemotactic response will impact bacterial transport relative to other processes such as advection and dispersion.
Micro- and nano- second time scale, high power electrical wire explosions in water.
Grinenko, Alon; Efimov, Sergey; Sayapin, Arkadii; Fedotov, Alexander; Gurovich, Viktor; Krasik, Yakov
2006-10-01
Experimental and magneto-hydro-dynamic simulation results of micro- and nanosecond time scale underwater electrical Al, Cu and W wires explosions are presented. A capacitor bank with stored energy up to 6 kJ (discharge current up to 80 kA with 2.5 μs quarter period) was used in microsecond time scale experiments and water forming line generator with current amplitude up to 100 kA and pulse duration of 100 ns were used in nanosecond time scale experiments. Extremely high energy deposition of up to 60 times the atomization enthalpy was registered in nanosecond time scale explosions. A discharge channel evolution and surface temperature were analyzed by streak shadow imaging and using fast photo-diode with a set of interference filters, respectively. Microsecond time scale electrical explosion of cylindrical wire array showed extremely high pressure of converging shock waves at the axis, up to 0.2 MBar. A 1D and 2D magneto-hydro-dynamic simulation demonstrated good agreement with such experimental parameters as discharge channel current, voltage, radius, and temperature.
Interplay between multiple length and time scales in complex chemical systems
Biman Bagchi; Charusita Chakravarty
2010-07-01
Processes in complex chemical systems, such as macromolecules, electrolytes, interfaces, micelles and enzymes, can span several orders of magnitude in length and time scales. The length and time scales of processes occurring over this broad time and space window are frequently coupled to give rise to the control necessary to ensure specificity and the uniqueness of the chemical phenomena. A combination of experimental, theoretical and computational techniques that can address a multiplicity of length and time scales is required in order to understand and predict structure and dynamics in such complex systems. This review highlights recent experimental developments that allow one to probe structure and dynamics at increasingly smaller length and time scales. The key theoretical approaches and computational strategies for integrating information across time-scales are discussed. The application of these ideas to understand phenomena in various areas, ranging from materials science to biology, is illustrated in the context of current developments in the areas of liquids and solvation, protein folding and aggregation and phase transitions, nucleation and self-assembly.
Shichao Sun
2015-01-01
Full Text Available This paper addressed the vehicle routing problem (VRP in large-scale urban transportation networks with stochastic time-dependent (STD travel times. The subproblem which is how to find the optimal path connecting any pair of customer nodes in a STD network was solved through a robust approach without requiring the probability distributions of link travel times. Based on that, the proposed STD-VRP model can be converted into solving a normal time-dependent VRP (TD-VRP, and algorithms for such TD-VRPs can also be introduced to obtain the solution. Numerical experiments were conducted to address STD-VRPTW of practical sizes on a real world urban network, demonstrated here on the road network of Shenzhen, China. The stochastic time-dependent link travel times of the network were calibrated by historical floating car data. A route construction algorithm was applied to solve the STD problem in 4 delivery scenarios efficiently. The computational results showed that the proposed STD-VRPTW model can improve the level of customer service by satisfying the time-window constraint under any circumstances. The improvement can be very significant especially for large-scale network delivery tasks with no more increase in cost and environmental impacts.
Mixing and flushing time scales in the Azhikode Estuary, southwest coast of India
Revichandran, C.; Pylee, A.
Flushing time scales of the Azhikode Estuary, Kerala, India showed pronounced dry season and wet season signals as well as large inter-annual variation. Cumulative flushing time of the estuary varies from 4.8 tide cycles in April to 1.22 tide cycles...
Time-scale decomposition of an optimal control problem in greenhouse climate management
Henten, van E.; Bontsema, J.
2009-01-01
Based on differences in dynamic response times in the crop production process, a hierarchical decomposition of greenhouse climate management is proposed. To a large extent the proposed decomposition builds on the time-scale decomposition of singularly perturbed systems commonly found in the
TIME SCALES OF FUSION-FISSION REACTIONS CALCULATED FROM PRESCISSION NEUTRON MULTIPLICITIES
SIWEKWILCZYNSKA, K; WILCZYNSKI, J; SIEMSSEN, RH; WILSCHUT, HW
1995-01-01
The time scale of fusion-fission reactions was found to be in the range from tau(f) = 5 . 10(-20) to 5 . 10(-19) s. This result was obtained from the analysis of the prescission neutron multiplicities with a new method combining the time-dependent statistical cascade calculations with the nuclear
Stability and Convergence of Solutions to Volterra Integral Equations on Time Scales
Eleonora Messina
2015-01-01
Full Text Available We consider Volterra integral equations on time scales and present our study about the long time behavior of their solutions. We provide sufficient conditions for the stability and investigate the convergence properties when the kernel of the equations vanishes at infinity.
Time Scale Analysis of Interest Rate Spreads and Output Using Wavelets
Marco Gallegati
2013-04-01
Full Text Available This paper adds to the literature on the information content of different spreads for real activity by explicitly taking into account the time scale relationship between a variety of monetary and financial indicators (real interest rate, term and credit spreads and output growth. By means of wavelet-based exploratory data analysis we obtain richer results relative to the aggregate analysis by identifying the dominant scales of variation in the data and the scales and location at which structural breaks have occurred. Moreover, using the “double residuals” regression analysis on a scale-by-scale basis, we find that changes in the spread in several markets have different information content for output at different time frames. This is consistent with the idea that allowing for different time scales of variation in the data can provide a fruitful understanding of the complex dynamics of economic relationships between variables with non-stationary or transient components, certainly richer than those obtained using standard time domain methods.
Martin, Andrew J.
2010-01-01
Increasingly, school leavers are taking time out from study or formal work after completing high school--often referred to as a "gap year" (involving structured activities such as "volunteer tourism" and unstructured activities such as leisure). Although much opinion exists about the merits--or otherwise--of taking time out after completing…
Martin, Andrew J.
2010-01-01
Increasingly, school leavers are taking time out from study or formal work after completing high school--often referred to as a "gap year" (involving structured activities such as "volunteer tourism" and unstructured activities such as leisure). Although much opinion exists about the merits--or otherwise--of taking time out after completing…
Urien, N; Lebrun, J D; Fechner, L C; Uher, E; François, A; Quéau, H; Coquery, M; Chaumot, A; Geffard, O
2016-05-15
Kinetic models have become established tools for describing trace metal bioaccumulation in aquatic organisms and offer a promising approach for linking water contamination to trace metal bioaccumulation in biota. Nevertheless, models are based on laboratory-derived kinetic parameters, and the question of their relevance to predict trace metal bioaccumulation in the field is poorly addressed. In the present study, we propose to assess the capacity of kinetic models to predict trace metal bioaccumulation in gammarids in the field at a wide spatial scale. The field validation consisted of measuring dissolved Cd, Cu, Ni and Pb concentrations in the water column at 141 sites in France, running the models with laboratory-derived kinetic parameters, and comparing model predictions and measurements of trace metal concentrations in gammarids caged for 7 days to the same sites. We observed that gammarids poorly accumulated Cu showing the limited relevance of that species to monitor Cu contamination. Therefore, Cu was not considered for model predictions. In contrast, gammarids significantly accumulated Pb, Cd, and Ni over a wide range of exposure concentrations. These results highlight the relevance of using gammarids for active biomonitoring to detect spatial trends of bioavailable Pb, Cd, and Ni contamination in freshwaters. The best agreements between model predictions and field measurements were observed for Cd with 71% of good estimations (i.e. field measurements were predicted within a factor of two), which highlighted the potential for kinetic models to link Cd contamination to bioaccumulation in the field. The poorest agreements were observed for Ni and Pb (39% and 48% of good estimations, respectively). However, models developed for Ni, Pb, and to a lesser extent for Cd, globally underestimated bioaccumulation in caged gammarids. These results showed that the link between trace metal concentration in water and in biota remains complex, and underlined the limits of
Long-time scale spectral diffusion in PMMA: Beyond the TLS model?
Müller, J.; Haarer, D.; Khodykin, O. V.; Kharlamov, B. M.
1999-05-01
Spectral diffusion (SD) in PMMA doped with H 2-TPP is investigated at 4.2 K on a time scale of 3 ÷ 10 6 s via optical hole burning. Two contradictory (in frames of the TLS model) results are obtained. The first is the absence of aging effects which put the upper limit for the TLS relaxation times to tens of minutes. The second is an intensive superlogarithmic SD on the whole time scale of the experiment, which evidences the presence of very slow relaxations, independent of the sample history on the time scale of up to 2 months. The presented results provide the clear evidence of the deviation of SD behavior from the TLS model predictions at moderately low temperatures. The concept of structural relaxations is applied for a qualitative interpretation of the experimental data.
Adaptive time splitting method for multi-scale evolutionary partial differential equations
Descombes, Stéphane; Dumont, Thierry; Louvet, Violaine; Massot, Marc
2011-01-01
This paper introduces an adaptive time splitting technique for the solution of stiff evolutionary PDEs that guarantees an effective error control of the simulation, independent of the fastest physical time scale for highly unsteady problems. The strategy considers a second order Strang method and another lower order embedded splitting scheme that takes into account potential loss of order due to the stiffness featured by time-space multi-scale phenomena. The scheme is then built upon a precise numerical analysis of the method and a complementary numerical procedure, conceived to overcome classical restrictions of adaptive time stepping schemes based on lower order embedded methods, whenever asymptotic estimates fail to predict the dynamics of the problem. The performance of the method in terms of control of integration errors is evaluated by numerical simulations of stiff propagating waves coming from nonlinear chemical dynamics models as well as highly multi-scale nanosecond repetitively pulsed gas discharge...
Junhao Hu
2014-01-01
Full Text Available We develop exponential stability of neutral stochastic functional differential equations with two-time-scale Markovian switching modeled by a continuous-time Markov chain which has a large state space. To overcome the computational effort and the complexity, we split the large-scale system into several classes and lump the states in each class into one class by the different states of changes of the subsystems; then, we give a limit system to effectively “replace” the large-scale system. Under suitable conditions, using the stability of the limit system as a bridge, the desired asymptotic properties of the large-scale system with Brownian motion and Poisson jump are obtained by utilizing perturbed Lyapunov function methods and Razumikhin-type criteria. Two examples are provided to demonstrate our results.
Time-scales of close-in exoplanet radio emission variability
See, V.; Jardine, M.; Fares, R.; Donati, J.-F.; Moutou, C.
2015-07-01
We investigate the variability of exoplanetary radio emission using stellar magnetic maps and 3D field extrapolation techniques. We use a sample of hot Jupiter hosting stars, focusing on the HD 179949, HD 189733 and τ Boo systems. Our results indicate two time-scales over which radio emission variability may occur at magnetized hot Jupiters. The first is the synodic period of the star-planet system. The origin of variability on this time-scale is the relative motion between the planet and the interplanetary plasma that is corotating with the host star. The second time-scale is the length of the magnetic cycle. Variability on this time-scale is caused by evolution of the stellar field. At these systems, the magnitude of planetary radio emission is anticorrelated with the angular separation between the subplanetary point and the nearest magnetic pole. For the special case of τ Boo b, whose orbital period is tidally locked to the rotation period of its host star, variability only occurs on the time-scale of the magnetic cycle. The lack of radio variability on the synodic period at τ Boo b is not predicted by previous radio emission models, which do not account for the co-rotation of the interplanetary plasma at small distances from the star.
Time-scales of close-in exoplanet radio emission variability
See, V; Fares, R; Donati, J -F; Moutou, C
2015-01-01
We investigate the variability of exoplanetary radio emission using stellar magnetic maps and 3D field extrapolation techniques. We use a sample of hot Jupiter hosting stars, focusing on the HD 179949, HD 189733 and tau Boo systems. Our results indicate two time-scales over which radio emission variability may occur at magnetised hot Jupiters. The first is the synodic period of the star-planet system. The origin of variability on this time-scale is the relative motion between the planet and the interplanetary plasma that is co-rotating with the host star. The second time-scale is the length of the magnetic cycle. Variability on this time-scale is caused by evolution of the stellar field. At these systems, the magnitude of planetary radio emission is anticorrelated with the angular separation between the subplanetary point and the nearest magnetic pole. For the special case of tau Boo b, whose orbital period is tidally locked to the rotation period of its host star, variability only occurs on the time-scale of...
Long term time variability of cosmic rays and possible relevance to the development of life on Earth
Erlykin, A D
2010-01-01
An analysis is made of the manner in which the cosmic ray intensity at Earth has varied over its existence and its possible relevance to both the origin and the evolution of life. Much of the analysis relates to the 'high energy' cosmic rays ($E>10^{14}eV;=0.1PeV$) and their variability due to the changing proximity of the solar system to supernova remnants which are generally believed to be responsible for most cosmic rays up to PeV energies. It is pointed out that, on a statistical basis, there will have been considerable variations in the likely 100 My between the Earth's biosphere reaching reasonable stability and the onset of very elementary life. Interestingly, there is the increasingly strong possibility that PeV cosmic rays are responsible for the initiation of terrestrial lightning strokes and the possibility arises of considerable increases in the frequency of lightnings and thereby the formation of some of the complex molecules which are the 'building blocks of life'. Attention is also given to the...
Multi-time Scale Coordination of Distributed Energy Resources in Isolated Power Systems
Mayhorn, Ebony; Xie, Le; Butler-Purry, Karen
2016-03-31
In isolated power systems, including microgrids, distributed assets, such as renewable energy resources (e.g. wind, solar) and energy storage, can be actively coordinated to reduce dependency on fossil fuel generation. The key challenge of such coordination arises from significant uncertainty and variability occurring at small time scales associated with increased penetration of renewables. Specifically, the problem is with ensuring economic and efficient utilization of DERs, while also meeting operational objectives such as adequate frequency performance. One possible solution is to reduce the time step at which tertiary controls are implemented and to ensure feedback and look-ahead capability are incorporated to handle variability and uncertainty. However, reducing the time step of tertiary controls necessitates investigating time-scale coupling with primary controls so as not to exacerbate system stability issues. In this paper, an optimal coordination (OC) strategy, which considers multiple time-scales, is proposed for isolated microgrid systems with a mix of DERs. This coordination strategy is based on an online moving horizon optimization approach. The effectiveness of the strategy was evaluated in terms of economics, technical performance, and computation time by varying key parameters that significantly impact performance. The illustrative example with realistic scenarios on a simulated isolated microgrid test system suggests that the proposed approach is generalizable towards designing multi-time scale optimal coordination strategies for isolated power systems.
Buckley, Patrick G; Das, Sudipto; Bryan, Kenneth; Watters, Karen M; Alcock, Leah; Koster, Jan; Versteeg, Rogier; Stallings, Raymond L
2011-05-15
The downregulation of specific genes through DNA hypermethylation is a major hallmark of cancer, although the extent and genomic distribution of hypermethylation occurring within cancer genomes is poorly understood. We report on the first genome-wide analysis of DNA methylation alterations in different neuroblastic tumor subtypes and cell lines, revealing higher order organization and clinically relevant alterations of the epigenome. The methylation status of 33,485 discrete loci representing all annotated CpG islands and RefSeq gene promoters was assessed in primary neuroblastic tumors and cell lines. A comparison of genes that were hypermethylated exclusively in the clinically favorable ganglioneuroma/ganglioneuroblastoma tumors revealed that nine genes were associated with poor clinical outcome when overexpressed in the unfavorable neuroblastoma (NB) tumors. Moreover, an integrated DNA methylation and copy number analysis identified 80 genes that were recurrently concomitantly deleted and hypermethylated in NB, with 37 reactivated by 5-aza-deoxycytidine. Lower expression of four of these genes was correlated with poor clinical outcome, further implicating their inactivation in aggressive disease pathogenesis. Analysis of genome-wide hypermethylation patterns revealed 70 recurrent large-scale blocks of contiguously hypermethylated promoters/CpG islands, up to 590 kb in length, with a distribution bias toward telomeric regions. Genome-wide hypermethylation events in neuroblastic tumors are extensive and frequently occur in large-scale blocks with a significant bias toward telomeric regions, indicating that some methylation alterations have occurred in a coordinated manner. Our results indicate that methylation contributes toward the clinicopathological features of neuroblastic tumors, revealing numerous genes associated with poor patient survival in NB.
Timing of millennial-scale climate change in Antarctica and Greenland during the last glacial period
Blunier, T; Brook, E J
2001-01-01
A precise relative chronology for Greenland and West Antarctic paleotemperature is extended to 90,000 years ago, based on correlation of atmospheric methane records from the Greenland Ice Sheet Project 2 and Byrd ice cores. Over this period, the onset of seven major millennial-scale warmings....... This pattern provides further evidence for the operation of a "bipolar see-saw" in air temperatures and an oceanic teleconnection between the hemispheres on millennial time scales....
Scale relativity and fractal space-time a new approach to unifying relativity and quantum mechanics
Nottale, Laurent
2011-01-01
This book provides a comprehensive survey of the development of the theory of scale relativity and fractal space-time. It suggests an original solution to the disunified nature of the classical-quantum transition in physical systems, enabling the basis of quantum mechanics on the principle of relativity, provided this principle is extended to scale transformations of the reference system. In the framework of such a newly generalized relativity theory (including position, orientation, motion and now scale transformations), the fundamental laws of physics may be given a general form that unifies
Beevers, Lindsay; Tilmant, Amaury; Mwelwa, Elenestina
2010-05-01
In large hydropower-dominated river basins, reservoirs are mainly operated so as to maximize revenues from energy generation regardless of the consequences of reduced flow fluctuation on downstream ecosystems. Revenue from hydropower plants is essential to a country's economy; however the impact on ecosystems downstream can be large-scale. The timing of flow releases does not mimic natural systems, which has impacts over different temporal and physio-spatial scales to the ecosystem. To inform decision making often hydro-economic modeling is used and it is essential that the response of the system is understood and incorporated adequately into assessment design, to allow for trade-offs to be identified. This requires issues of timing and spatial scale to be understood and incorporated over different planning horizons. Nesting these issues of scale into decisions is complex; where decisions are made on timescales from hours to months and spatially within a basin depending on the operation of the system. Up-scaling the most critical interactions between flow, form and ecosystem into the decision making process, for different time horizons or planning scales, is essential. A proposed framework is illustrated with the Zambezi basin.
Farrell, Ross R.; Wellinger, Marco; Gloess, Alexia N.; Nichols, David S.; Breadmore, Michael C.; Shellie, Robert A.; Yeretzian, Chahan
2015-11-01
We introduce a real-time method to monitor the evolution of oak aromas during the oak toasting process. French and American oak wood boards were toasted in an oven at three different temperatures, while the process-gas was continuously transferred to the inlet of a proton-transfer-reaction time-of-flight mass spectrometer for online monitoring. Oak wood aroma compounds important for their sensory contribution to oak-aged wine were tentatively identified based on soft ionization and molecular mass. The time-intensity profiles revealed toasting process dynamics illustrating in real-time how different compounds evolve from the oak wood during toasting. Sufficient sensitivity was achieved to observe spikes in volatile concentrations related to cracking phenomena on the oak wood surface. The polysaccharide-derived compounds exhibited similar profiles; whilst for lignin-derived compounds eugenol formation differed from that of vanillin and guaiacol at lower toasting temperatures. Significant generation of oak lactone from precursors was evident at 225 oC. Statistical processing of the real-time aroma data showed similarities and differences between individual oak boards and oak wood sourced from the different origins. This study enriches our understanding of the oak toasting process and demonstrates a new analytical approach for research on wood volatiles.
Christopher Fischer
2016-01-01
Full Text Available For semicrystalline thermoplastics, aside from pressure and shear, the temperature-time behavior while cooling the melt significantly affects the geometry and degree of ordered structures (e.g., spherulite size, degree of crystallization, and crystal modification and, as a consequence, the resulting global component properties. Previous research has shown that a higher isothermal holding temperature (e.g., mold temperature and chill-roll temperature leads to the formation of more distinct ordered structures and, therefore, can lead to greater stiffness and strength. Nevertheless, isothermal holding time during manufacturing is typically not taken into account. In this paper, fast scanning calorimetry (FSC measurements were taken using polypropylene to analyze the crystallization during idealized temperature-time profiles based on the dynamic temperature process and to investigate the crystallization behavior at different temperatures and isothermal holding times analytically. Furthermore, iPP foils were extruded and tested mechanically to investigate the knowledge gained experimentally. Analytical and mechanical results show that foils produced at the same isothermal holding temperature can obtain significantly different ordered structures and mechanical properties depending primarily on the isothermal holding time.
Beltrame, Ludovica; Carbonin, Daniele; Galelli, Stefano; Castelletti, Andrea
2014-05-01
Population growth, water scarcity and climate change are three major factors making the understanding of variations in water availability increasingly important. Therefore, reliable medium-to-long range forecasts of streamflows are essential to the development of water management policies. To this purpose, recent modelling efforts have been dedicated to seasonal and inter-annual streamflow forecasts based on the teleconnection between "at-site" hydro-meteorological processes and low frequency climate fluctuations, such as El Niño Southern Oscillation (ENSO). This work proposes a novel procedure for first detecting the impact of ENSO on hydro-meteorological processes at the catchment scale, and then assessing the potential of ENSO indicators for building medium-to-long range statistical streamflow prediction models. Core of this procedure is the adoption of the Iterative Input variable Selection (IIS) algorithm that is employed to find the most relevant forcings of streamflow variability and derive predictive models based on the selected inputs. The procedure is tested on the Columbia (USA) and Williams (Australia) Rivers, where ENSO influence has been well-documented, and then adopted on the unexplored Red River basin (Vietnam). Results show that IIS outcomes on the Columbia and Williams Rivers are consistent with the results of previous studies, and that ENSO indicators can be effectively used to enhance the streamflow forecast models capabilities. The experiments on the Red River basin show that the ENSO influence is less pronounced, inducing little effects on the basin hydro-meteorological processes.
Defining a Trend for a Time Series Which Makes Use of the Intrinsic Time-Scale Decomposition
Restrepo, Juan M; Comeau, Darin; Flaschka, Hermann
2014-01-01
We propose criteria that define a trend for time series with inherent multi-scale features. We call this trend the {\\it tendency} of a time series. The tendency is defined empirically by a set of criteria and captures the large-scale temporal variability of the original signal as well as the most frequent events in its histogram. Among other properties, the tendency has a variance no larger than that of the original signal; the histogram of the difference between the original signal and the tendency is as symmetric as possible; and with reduced complexity, the tendency captures essential features of the signal. To find the tendency we first use the Intrinsic Time-Scale Decomposition (ITD) of the signal, introduced in 2007 by Frei and Osorio, to produce a set of candidate tendencies. We then apply the criteria to each of the candidates to single out the one that best agrees with them. While the criteria for the tendency are independent of the signal decomposition scheme, it is found that the ITD is a simple an...
Scaling of Langevin and molecular dynamics persistence times of nonhomogeneous fluids.
Olivares-Rivas, Wilmer; Colmenares, Pedro J
2012-01-01
The existing solution for the Langevin equation of an anisotropic fluid allowed the evaluation of the position-dependent perpendicular and parallel diffusion coefficients, using molecular dynamics data. However, the time scale of the Langevin dynamics and molecular dynamics are different and an ansatz for the persistence probability relaxation time was needed. Here we show how the solution for the average persistence probability obtained from the backward Smoluchowski-Fokker-Planck equation (SE), associated to the Langevin dynamics, scales with the corresponding molecular dynamics quantity. Our SE perpendicular persistence time is evaluated in terms of simple integrals over the equilibrium local density. When properly scaled by the perpendicular diffusion coefficient, it gives a good match with that obtained from molecular dynamics.
Feasibility of measuring the Shapiro time delay over meter-scale distances
Ballmer, S [Syracuse University, Syracuse, NY 13244 (United States); Marka, S [Columbia University in the City of New York, New York, NY 10027 (United States); Shawhan, P, E-mail: sballmer@ligo.caltech.ed, E-mail: smarka@phys.columbia.ed, E-mail: pshawhan@umd.ed [University of Maryland, College Park, MD 20742 (United States)
2010-09-21
The time delay of light as it passes by a massive object, first calculated by Shapiro in 1964, is a hallmark of the curvature of spacetime. To date, all measurements of the Shapiro time delay have been made over solar-system distance scales. We show that the new generation of kilometer-scale laser interferometers being constructed as gravitational wave detectors, in particular Advanced LIGO, will in principle be sensitive enough to measure variations in the Shapiro time delay produced by a suitably designed rotating object placed near the laser beam. We show that such an apparatus is feasible (though not easy) to construct, present an example design, and calculate the signal that would be detectable by Advanced LIGO. This offers the first opportunity to measure spacetime curvature effects on a laboratory distance scale.
Gómez-Uribe, Carlos A; Verghese, George C; Tzafriri, Abraham R
2008-12-28
Widely different time scales are common in systems of chemical reactions and can be exploited to obtain reduced models applicable to the time scales of interest. These reduced models enable more efficient computation and simplify analysis. A classic example is the irreversible enzymatic reaction, for which separation of time scales in a deterministic mass action kinetics model results in approximate rate laws for the slow dynamics, such as that of Michaelis-Menten. Recently, several methods have been developed for separation of slow and fast time scales in chemical master equation (CME) descriptions of stochastic chemical kinetics, yielding separate reduced CMEs for the slow variables and the fast variables. The paper begins by systematizing the preliminary step of identifying slow and fast variables in a chemical system from a specification of the slow and fast reactions in the system. The authors then present an enhanced time-scale-separation method that can extend the validity and improve the accuracy of existing methods by better accounting for slow reactions when equilibrating the fast subsystem. The resulting method is particularly accurate in systems such as enzymatic and protein interaction networks, where the rates of the slow reactions that modify the slow variables are not a function of the slow variables. The authors apply their methodology to the case of an irreversible enzymatic reaction and show that the resulting improvements in accuracy and validity are analogous to those obtained in the deterministic case by using the total quasi-steady-state approximation rather than the classical Michaelis-Menten. The other main contribution of this paper is to show how mass fluctuation kinetics models, which give approximate evolution equations for the means, variances, and covariances of the concentrations in a chemical system, can feed into time-scale-separation methods at a variety of stages.
Response of vegetation to drought time-scales across global land biomes.
Vicente-Serrano, Sergio M; Gouveia, Célia; Camarero, Jesús Julio; Beguería, Santiago; Trigo, Ricardo; López-Moreno, Juan I; Azorín-Molina, César; Pasho, Edmond; Lorenzo-Lacruz, Jorge; Revuelto, Jesús; Morán-Tejeda, Enrique; Sanchez-Lorenzo, Arturo
2013-01-02
We evaluated the response of the Earth land biomes to drought by correlating a drought index with three global indicators of vegetation activity and growth: vegetation indices from satellite imagery, tree-ring growth series, and Aboveground Net Primary Production (ANPP) records. Arid and humid biomes are both affected by drought, and we suggest that the persistence of the water deficit (i.e., the drought time-scale) could be playing a key role in determining the sensitivity of land biomes to drought. We found that arid biomes respond to drought at short time-scales; that is, there is a rapid vegetation reaction as soon as water deficits below normal conditions occur. This may be due to the fact that plant species of arid regions have mechanisms allowing them to rapidly adapt to changing water availability. Humid biomes also respond to drought at short time-scales, but in this case the physiological mechanisms likely differ from those operating in arid biomes, as plants usually have a poor adaptability to water shortage. On the contrary, semiarid and subhumid biomes respond to drought at long time-scales, probably because plants are able to withstand water deficits, but they lack the rapid response of arid biomes to drought. These results are consistent among three vegetation parameters analyzed and across different land biomes, showing that the response of vegetation to drought depends on characteristic drought time-scales for each biome. Understanding the dominant time-scales at which drought most influences vegetation might help assessing the resistance and resilience of vegetation and improving our knowledge of vegetation vulnerability to climate change.
Jesus A Garrido
2013-05-01
Full Text Available The way long-term synaptic plasticity regulates neuronal spike patterns is not completely understood. This issue is especially relevant for the cerebellum, which is endowed with several forms of long-term synaptic plasticity and has been predicted to operate as a timing and a learning machine. Here we have used a computational model to simulate the impact of multiple distributed synaptic weights in the cerebellar granular layer network. In response to mossy fiber bursts, synaptic weights at multiple connections played a crucial role to regulate spike number and positioning in granule cells. The weight at mossy fiber to granule cell synapses regulated the delay of the first spike and the weight at mossy fiber and parallel fiber to Golgi cell synapses regulated the duration of the time-window during which the first-spike could be emitted. Moreover, the weights of synapses controlling Golgi cell activation regulated the intensity of granule cell inhibition and therefore the number of spikes that could be emitted. First spike timing was regulated with millisecond precision and the number of spikes ranged from 0 to 3. Interestingly, different combinations of synaptic weights optimized either first-spike timing precision or spike number, efficiently controlling transmission and filtering properties. These results predict that distributed synaptic plasticity regulates the emission of quasi-digital spike patterns on the millisecond time scale and allows the cerebellar granular layer to flexibly control burst transmission along the mossy fiber pathway.
Computational Fluid Dynamics Study on the Effects of RATO Timing on the Scale Model Acoustic Test
Nielsen, Tanner; Williams, B.; West, Jeff
2015-01-01
The Scale Model Acoustic Test (SMAT) is a 5% scale test of the Space Launch System (SLS), which is currently being designed at Marshall Space Flight Center (MSFC). The purpose of this test is to characterize and understand a variety of acoustic phenomena that occur during the early portions of lift off, one being the overpressure environment that develops shortly after booster ignition. The SLS lift off configuration consists of four RS-25 liquid thrusters on the core stage, with two solid boosters connected to each side. Past experience with scale model testing at MSFC (in ER42), has shown that there is a delay in the ignition of the Rocket Assisted Take Off (RATO) motor, which is used as the 5% scale analog of the solid boosters, after the signal to ignite is given. This delay can range from 0 to 16.5ms. While this small of a delay maybe insignificant in the case of the full scale SLS, it can significantly alter the data obtained during the SMAT due to the much smaller geometry. The speed of sound of the air and combustion gas constituents is not scaled, and therefore the SMAT pressure waves propagate at approximately the same speed as occurs during full scale. However, the SMAT geometry is much smaller allowing the pressure waves to move down the exhaust duct, through the trench, and impact the vehicle model much faster than occurs at full scale. To better understand the effect of the RATO timing simultaneity on the SMAT IOP test data, a computational fluid dynamics (CFD) analysis was performed using the Loci/CHEM CFD software program. Five different timing offsets, based on RATO ignition delay statistics, were simulated. A variety of results and comparisons will be given, assessing the overall effect of RATO timing simultaneity on the SMAT overpressure environment.
Hinderer, J.; Hector, B.; Séguis, L.; Descloitres, M.; Cohard, J.; Boy, J.; Calvo, M.; Rosat, S.; Riccardi, U.; Galle, S.
2013-12-01
Water storage changes (WSC) are investigated by the mean of gravity monitoring in Djougou, northern Benin, in the frame of the GHYRAF (Gravity and Hydrology in Africa) project. In this area, WSC are 1) part of the control system for evapotranspiration (ET) processes, a key variable of the West-African monsoon cycle and 2) the state variable for resource management, a critical issue in storage-poor hard rock basement contexts such as in northern Benin. We show the advantages of gravity monitoring for analyzing different processes in the water cycle involved at various time and space scales, using the main gravity sensors available today (FG5 absolute gravimeter, superconducting gravimeter -SG- and CG5 micro-gravimeter). The study area is also part of the long-term observing system AMMA-Catch, and thus under intense hydro-meteorological monitoring (rain, soil moisture, water table level, ET ...). Gravity-derived WSC are compared at all frequencies to hydrological data and to hydrological models calibrated on these data. Discrepancies are analyzed to discuss the pros and cons of each approach. Fast gravity changes (a few hours) are significant when rain events occur, and involve different contributions: rainfall itself, runoff, fast subsurface water redistribution, screening effect of the gravimeter building and local topography. We investigate these effects and present the statistical results of a set of rain events recorded with the SG installed in Djougou since July 2010. The intermediate time scale of gravity changes (a few days) is caused by ET and both vertical and horizontal water redistribution. The integrative nature of gravity measurements does not allow to separate these different contributions, and the screening from the shelter reduces our ability to retrieve ET values. Also, atmospheric corrections are critical at such frequencies, and deserve some specific attention. However, a quick analysis of gravity changes following rain events shows that the
Digital signal processing techniques for pitch shifting and time scaling of audio signals
Buś, Szymon; Jedrzejewski, Konrad
2016-09-01
In this paper, we present the techniques used for modifying the spectral content (pitch shifting) and for changing the time duration (time scaling) of an audio signal. A short introduction gives a necessary background for understanding the discussed issues and contains explanations of the terms used in the paper. In subsequent sections we present three different techniques appropriate both for pitch shifting and for time scaling. These techniques use three different time-frequency representations of a signal, namely short-time Fourier transform (STFT), continuous wavelet transform (CWT) and constant-Q transform (CQT). The results of simulation studies devoted to comparison of the properties of these methods are presented and discussed in the paper.
Scaling properties of rainfall time-series in the urban area of Rome
Volpi, E.; Napolitano, F.; Lombardo, F.
2009-04-01
The rainfall fields exhibits a high space-time variability which generates a large degree of uncertainty in modelling the process, thus causing lack of accuracy in many key hydrological problems, such as the forecasting of floods and the management of water resources. The large amount of literature produced in the last thirty years about this issue deals with the development of stochastic models able to represent the non-linearity and intermittence of rainfall in order to perform the downscaling process, i.e. transferring to finer scales the information on rainfall observed or forecasted at large scales. Traditionally, these models are based upon point processes in both the time (e.g. Waymire and Gupta, 1981) and the space-time domain (e.g. Rodriguez-Iturbe et al., 1986). Although this approach is cluster-based so as to model the physical structure of rainfall, its application may involve an inconvenient mathematical complexity and a large number of parameters, leading to several problems in parameter estimation. Another approach to this problem is based on the empirical detection of some regularity in hydrological observations, such as the scale-invariance properties of rainfall (e.g. Lovejoy and Schertzer, 1985). Models following this approach are based upon the assumption of a power law dependence of all statistical moments on the scale of aggregation. That means scaling properties can provide simple relationships to link the statistical distribution of the rainfall process at different spatial and temporal scales, in the ranges of which the power-low assumption can be verified (Marani, 2003). This work focuses on the analysis of the scaling properties of rainfall time series from a high density rain gauge network covering the Rome's urban area. The network consists of 24 sites, and the gauge record at each site has 10-minute time resolution and about 16-year length (1992-2007). The aim of the study is the identification of temporal scaling regimes, their ranges
Oscillation Criteria for Second-Order Quasilinear Neutral Delay Dynamic Equations on Time Scales
Guangrong Zhang
2010-01-01
Full Text Available We establish some new oscillation criteria for the second-order quasilinear neutral delay dynamic equations [r(t(zΔ(tγ]Δ+q1(txα(τ1(t+q2(txβ(τ2(t=0 on a time scale 𝕋, where z(t=x(t+p(tx(τ0(t, 0<α<γ<β. Our results generalize and improve some known results for oscillation of second-order nonlinear delay dynamic equations on time scales. Some examples are considered to illustrate our main results.
Gotzig, B. [Laboratoire d`Electrotechnique de Grenoble (France)]|[Schneider Electric S.A., Grenoble (France); Hadjsaid, N.; Feuillet, R. [Laboratoire d`Electrotechnique de Grenoble (France); Jeannot, R. [Schneider Electric S.A., Grenoble (France)
1998-12-31
Optimization of large scale distribution systems on a real time base requires computationally efficient algorithms. In this paper a fast general branch exchange algorithm is proposed. Depending on the objective function which is optimized, both the line loss reduction in the normal state and the restoration of de-energized loads can be carried out. Tests were carried out on a real large scale distribution network. They demonstrate that the method is fast and that it can be used in distribution management systems on real time base. (author)
Characteristic time scales in the American dollar-Mexican peso exchange currency market
Alvarez-Ramirez, Jose
2002-06-01
Daily fluctuations of the American dollar-Mexican peso exchange currency market are studied using multifractal analysis methods. It is found evidence of multiaffinity of daily fluctuations in the sense that the qth-order (roughness) Hurst exponent Hq varies with changes in q. It is also found that there exist several characteristic time scales ranging from week to year. Accordingly, the market exhibits persistence in the sense that instabilities introduced by market events acting around the characteristic time scales (mainly, quarter and year) would propagate through the future market activity. Some implications of our results on the regulation of the dollar-mexpeso market activity are discussed.
Doubly stochastic Poisson process models for precipitation at fine time-scales
Ramesh, Nadarajah I.; Onof, Christian; Xie, Dichao
2012-09-01
This paper considers a class of stochastic point process models, based on doubly stochastic Poisson processes, in the modelling of rainfall. We examine the application of this class of models, a neglected alternative to the widely-known Poisson cluster models, in the analysis of fine time-scale rainfall intensity. These models are mainly used to analyse tipping-bucket raingauge data from a single site but an extension to multiple sites is illustrated which reveals the potential of this class of models to study the temporal and spatial variability of precipitation at fine time-scales.
On Qualitative Analysis of Delay Systems and $x^ = f (t, x, x^)$ on Time Scales
Yajun Ma; Yu Zhang; Jitao Sun
2010-04-01
Here we solve two problems presented in paper [9] (C C Tisdell and A Zaidi, Basic qualitative and quantitative results for solutions to nonlinear, dynamic equations on time scales with an application to economic modelling, Nonlinear Anal. 68 (2008) 3504–3524). We study existence and uniqueness of solutions for delay systems and first-order dynamic equations of the form $x^=f(t,x,x^)$ on time scales by using the Banach’s fixed-point theorem. Some examples are presented to illustrate the efficiency of the proposed results.
Ranasinghe, R.W.M.R.J.B.; Holman, R.; De Schipper, M.A.; Lippmann, T.; Wehof, J.; Duong, T.M.; Roelvink, D.; Stive, M.J.F.
2012-01-01
Time scales of post-storm nearshore morphological recovery and physical processes governing these time scales are poorly understood at present. The ability to predict nearshore morphological recovery time scales based on pre-, during- or post-resetting storm conditions is an essential requirement fo
Relating the large-scale structure of time series and visibility networks.
Rodríguez, Miguel A
2017-06-01
The structure of time series is usually characterized by means of correlations. A new proposal based on visibility networks has been considered recently. Visibility networks are complex networks mapped from surfaces or time series using visibility properties. The structures of time series and visibility networks are closely related, as shown by means of fractional time series in recent works. In these works, a simple relationship between the Hurst exponent H of fractional time series and the exponent of the distribution of edges γ of the corresponding visibility network, which exhibits a power law, is shown. To check and generalize these results, in this paper we delve into this idea of connected structures by defining both structures more properly. In addition to the exponents used before, H and γ, which take into account local properties, we consider two more exponents that, as we will show, characterize global properties. These are the exponent α for time series, which gives the scaling of the variance with the size as var∼T^{2α}, and the exponent κ of their corresponding network, which gives the scaling of the averaged maximum of the number of edges, 〈k_{M}〉∼N^{κ}. With this representation, a more precise connection between the structures of general time series and their associated visibility network is achieved. Similarities and differences are more clearly established, and new scaling forms of complex networks appear in agreement with their respective classes of time series.
Christopher Fischer; Dietmar Drummer
2016-01-01
For semicrystalline thermoplastics, aside from pressure and shear, the temperature-time behavior while cooling the melt significantly affects the geometry and degree of ordered structures (e.g., spherulite size, degree of crystallization, and crystal modification) and, as a consequence, the resulting global component properties. Previous research has shown that a higher isothermal holding temperature (e.g., mold temperature and chill-roll temperature) leads to the formation of more distinct o...
Murari, A., E-mail: andrea.murari@igi.cnr.it [Associazione EURATOM-ENEA per la Fusione, Consorzio RFX, 4-35127 Padova (Italy); Vega, J. [Asociacion EURATOM-CIEMAT para Fusion, CIEMAT, Madrid (Spain); Mazon, D. [Association EURATOM-CEA, CEA Cadarache, 13108 Saint-Paul-lez-Durance (France); Ratta, G.A. [Asociacion EURATOM-CIEMAT para Fusion, CIEMAT, Madrid (Spain); Gelfusa, M. [Associazione EURATOM-ENEA - University of Rome ' Tor Vergata' , Roma (Italy); Debrie, A. [Arts et Metiers ParisTech Engineering College (ENSAM), 75013 Paris (France); Boulbe, C.; Faugeras, B. [Laboratoire J-A Dieudonne (UMR 66 21), Universite de Nice Sophia-Antipolis, CNRS Parc Valrose, 06108 Nice Cedex 02 (France)
2011-10-15
A general trend in the experimental programmes of present day Tokamaks, and of JET in particular, is the constant increase in the number of parameters to be controlled in real time, to satisfy the machine protection requirements on the one hand and to improve performance on the other. Since the amount of data collected is also increasing at least at a rate compatible with the Moore law, significant developments are required in the field of real time algorithms particularly for magnetic reconstructions, disruption prediction and image processing. A new real time equilibrium code called EQUINOX, using internal and external measurements of the magnetic fields, has been qualified on JET. It can provide reconstructed accurate equilibria about every 50 ms on a 2 GHz PC. An advanced disruption predictor, based on machine learning tools, has been deployed using inputs selected with a genetic algorithm. Its success rate remains of the order of 94% for up to 170 ms before the occurrence of the disruption. Nonextensive entropies, which are more sensitive to long range correlations, seem to be useful in detecting vibrations in the videos of JET cameras, both visible and infrared.
Influence of the time scale on the construction of financial networks.
Frank Emmert-Streib
Full Text Available BACKGROUND: In this paper we investigate the definition and formation of financial networks. Specifically, we study the influence of the time scale on their construction. METHODOLOGY/PRINCIPAL FINDINGS: For our analysis we use correlation-based networks obtained from the daily closing prices of stock market data. More precisely, we use the stocks that currently comprise the Dow Jones Industrial Average (DJIA and estimate financial networks where nodes correspond to stocks and edges correspond to none vanishing correlation coefficients. That means only if a correlation coefficient is statistically significant different from zero, we include an edge in the network. This construction procedure results in unweighted, undirected networks. By separating the time series of stock prices in non-overlapping intervals, we obtain one network per interval. The length of these intervals corresponds to the time scale of the data, whose influence on the construction of the networks will be studied in this paper. CONCLUSIONS/SIGNIFICANCE: Numerical analysis of four different measures in dependence on the time scale for the construction of networks allows us to gain insights about the intrinsic time scale of the stock market with respect to a meaningful graph-theoretical analysis.
Scaling analysis of high-frequency time series of gamma-ray counts
Barbosa, Susana; Azevedo, Eduardo
2017-04-01
Gamma radiation is being monitored in a dedicated campaign set-up at the Eastern North Atlantic (ENA) facility located in the Graciosa island (Azores), a fixed site of the Atmospheric Radiation Measurement programme (ARM), established and supported by the Department of Energy (DOE) of the United States of America with the collaboration of the Government of the Autonomous Region of the Azores and University of the Azores. The temporal variability of gamma radiation is mainly determined by the time-varying concentration of radon progeny, which in turn is influenced by meteorological conditions and precipitation scavenging. The resulting time series of high-frequency (1-minute) gamma-ray counts displays therefore a complex temporal structure on multiple time scales, including long-range dependent behavior. This work addresses the scaling properties of the time series of gamma-ray counts from the ENA site (data freely available from the ARM data archive) using both wavelet and model-based methods for the estimation of the scaling exponent. The time series is dominated by sharp peaks associated with events of strong precipitation. The effect of these peaks on the estimation of the scaling exponent, as well as the effect of temporal aggregation (1-minute versus 15-minute aggregated data) is further addressed.
Influence of the time scale on the construction of financial networks.
Emmert-Streib, Frank; Dehmer, Matthias
2010-09-30
In this paper we investigate the definition and formation of financial networks. Specifically, we study the influence of the time scale on their construction. For our analysis we use correlation-based networks obtained from the daily closing prices of stock market data. More precisely, we use the stocks that currently comprise the Dow Jones Industrial Average (DJIA) and estimate financial networks where nodes correspond to stocks and edges correspond to none vanishing correlation coefficients. That means only if a correlation coefficient is statistically significant different from zero, we include an edge in the network. This construction procedure results in unweighted, undirected networks. By separating the time series of stock prices in non-overlapping intervals, we obtain one network per interval. The length of these intervals corresponds to the time scale of the data, whose influence on the construction of the networks will be studied in this paper. Numerical analysis of four different measures in dependence on the time scale for the construction of networks allows us to gain insights about the intrinsic time scale of the stock market with respect to a meaningful graph-theoretical analysis.
Large-scale structure effects on the gravitational lens image positions and time delay
Seljak, Uros
1994-01-01
We compute the fluctuations in gravitational lens image positions and time delay caused by large-scale structure correlations. We show that these fluctuations can be expressed as a simple integral over the density power spectrum. Using the Cosmic Background Explorer (COBE) normalization we find that positions of objects at cosmological distances are expected to deviate from their true positions by few arcminutes. These deflections are not directly observable. The positions of the images relative to one another fluctuate by a few percent of the relative separation, implying that one does not expect multiple images to be produced by large-scale structure. Nevertheless, the fluctuations are larger than the observational errors on the positions and affect reconstructions of the lens potential. The time delay fluctuations have a geometrical and a gravitational contribution. Both are much larger than the expected time delay from the primary lens, but partially cancel each other. We find that large-scale structure weakly affects the time delay and time delay measurements can be used as a probe of the distance scale in the universe.
Streamflow response of a small forested catchment on different time scales
A. Zabaleta
2012-08-01
Full Text Available The hydrological response of a catchment to rainfall on different time scales is result of a complex system involving a range of physical processes which may operate simultaneously and have different spatial and temporal influences. This paper presents the analysis of streamflow response of a small humid-temperate catchment (Aixola, 4.8 km^{2} in the Basque Country on different time scales and discusses the role of the controlling factors. Firstly, daily time series analysis was used to establish a hypothesis on the general functioning of the catchment through the relationship between precipitation and discharge on an annual and multi-annual scale (2003–2008. Second, rainfall-runoff relationships and relationships among several hydrological variables, including catchment antecedent conditions, were explored at the event scale (222 events to check and improve the hypothesis. Finally, the evolution of electrical conductivity (EC during some of the monitored storm events (28 events was examined to identify the time-origin of waters. Quick response of the catchment to almost all the rainfall events as well as a considerable regulation capacity was deduced from the correlation and spectral analyses. These results agree with runoff event scale data analysis; however the event analysis revealed the non-linearity of the system, as antecedent conditions play a significant role in this catchment. Further, analysis at the event scale made possible to clarify factors controlling (precipitation, precipitation intensity and initial discharge the different aspects of the runoff response (runoff coefficient and discharge increase for this catchment. Finally, the evolution of EC of the waters enabled the time origin (event or pre-event waters of the quickflow to be established; specifically, the conductivity showed that pre-event waters usually represent a high percentage of the total discharge during runoff peaks. The importance of soil waters in the
Steele, A. Duncan; Madhi, Shabir A.; Cunliffe, Nigel A.; Vesikari, Timo; Phua, Kong Boo; Lim, Fong Seng; Nelson, E. Anthony S.; Lau, Yu-Lung; Huang, Li-Min; Karkada, Naveen; Debrus, Serge; Han, Htay Htay; Benninghoff, Bernd
2016-01-01
ABSTRACT Variability in rotavirus gastroenteritis (RVGE) epidemiology can influence the optimal vaccination schedule. We evaluated regional trends in the age of RVGE episodes in low- to middle- versus high-income countries in three continents. We undertook a post-hoc analysis based on efficacy trials of a human rotavirus vaccine (HRV; Rotarix™, GSK Vaccines), in which 1348, 1641, and 5250 healthy infants received a placebo in Europe (NCT00140686), Africa (NCT00241644), and Asia (NCT00197210, NCT00329745). Incidence of any/severe RVGE by age at onset was evaluated by active surveillance over the first two years of life. Severity of RVGE episodes was assessed using the Vesikari-scale. The incidence of any RVGE in Africa was higher than in Europe during the first year of life (≤2.78% vs. ≤2.03% per month), but much lower during the second one (≤0.86% versus ≤2.00% per month). The incidence of severe RVGE in Africa was slightly lower than in Europe during the first year of life. Nevertheless, temporal profiles for the incidence of severe RVGE in Africa and Europe during the first (≤1.00% and ≤1.23% per month) and second (≤0.53% and ≤1.13% per month) years of life were similar to those of any RVGE. Any/severe RVGE incidences peaked at younger ages in Africa vs. Europe. In high-income Asian regions, severe RVGE incidence (≤0.31% per month) remained low during the study. The burden of any RVGE was higher earlier in life in children from low- to middle- compared with high-income countries. Differing rotavirus vaccine schedules are likely warranted to maximize protection in different settings. PMID:27260009
Nondriven Polymer Translocation Through a Nanopore:Scaling for Translocation Time with Chain Length
LI Hui; ZHANG Jing; LIU Hong; SUN Chia-chung
2011-01-01
We investigated the dynamics of the passage for a polymer chain through a nanopore in the absence of any external driving force with Weeks-Chandler-Andersen potential in two-dimensional simulations,in particular,focused our attention on the scaling law of the mean translocation time.We found that the effect of hydrodynamic interactions is the major factor in determining the scaling exponents with increasing pore size.The scaling close to N1+2v was observed when the hydrodynamic interactions were screened in the cases of small pore sizes,while the scaling close to N3v was obtained when the hydrodynamic interactions were present in the cases of large pore sizes.
Multi-scale symbolic time reverse analysis of gas-liquid two-phase flow structures
Wang, Hongmei; Zhai, Lusheng; Jin, Ningde; Wang, Youchen
Gas-liquid two-phase flows are widely encountered in production processes of petroleum and chemical industry. Understanding the dynamic characteristics of multi-scale gas-liquid two-phase flow structures is of great significance for the optimization of production process and the measurement of flow parameters. In this paper, we propose a method of multi-scale symbolic time reverse (MSTR) analysis for gas-liquid two-phase flows. First, through extracting four time reverse asymmetry measures (TRAMs), i.e. Euclidean distance, difference entropy, percentage of constant words and percentage of reversible words, the time reverse asymmetry (TRA) behaviors of typical nonlinear systems are investigated from the perspective of multi-scale analysis, and the results show that the TRAMs are sensitive to the changing of dynamic characteristics underlying the complex nonlinear systems. Then, the MSTR analysis is used to study the conductance signals from gas-liquid two-phase flows. It is found that the multi-scale TRA analysis can effectively reveal the multi-scale structure characteristics and nonlinear evolution properties of the flow structures.
Measuring collective behaviour of multicellular ensembles: role of space–time scales
S Rajesh; Somdatta Sinha
2008-06-01
Living systems are spectacular examples of spatiotemporally organized structures. During the development of complex organization there is dynamic equilibrium between the local and global processes acting at the intra- and intercellular levels in multiple space and time scales. Although in modelling studies such spatiotemporal systems can be described by different space–time scales and at many organizational levels, the experimental quantities measured and predictions useful for practical applications are at a macroscopic (coarser or averaged) level/scale; these are limited by the resolution of the measuring method and experimental protocol. In this work, we address whether the spatiotemporal collective dynamics exhibited by a multiscale system can discriminate between, or be borne out by, the coarse-grained and averaged measurements done at different spatial and temporal scales. Using a simple model of a ring of cells, we show that measurements of both spatial and spatiotemporal average behaviour in this multicellular ensemble can mask the variety of collective dynamics observed at other space–time scales, and exhibit completely different behaviours. Such outcomes of measurements can lead to incomplete and incorrect understanding of physiological functions and pathogenesis in multicell ensembles.
2017-02-01
other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/CERL SR-17-2 iii Contents...a respondent. Answers can indicate decision-making criteria when the population does not have water available to them in their homes or home...C35. Scooter parking lot in Rome , Italy (dreamstime.com, 2016). ERDC/CERL SR-17-2 189 Question T2a. What time of day is traffic heaviest on
Zhao, Yue; Fairhurst, Michelle C.; Wingen, Lisa M.; Perraud, Véronique; Ezell, Michael J.; Finlayson-Pitts, Barbara J.
2017-04-01
The application of direct analysis in real-time mass spectrometry (DART-MS), which is finding increasing use in atmospheric chemistry, to two different laboratory model systems for airborne particles is investigated: (1) submicron C3-C7 dicarboxylic acid (diacid) particles reacted with gas-phase trimethylamine (TMA) or butylamine (BA) and (2) secondary organic aerosol (SOA) particles from the ozonolysis of α-cedrene. The diacid particles exhibit a clear odd-even pattern in their chemical reactivity toward TMA and BA, with the odd-carbon diacid particles being substantially more reactive than even ones. The ratio of base to diacid in reacted particles, determined using known diacid-base mixtures, was compared to that measured by high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS), which vaporizes the whole particle. Results show that DART-MS probes ˜ 30 nm of the surface layer, consistent with other studies on different systems. For α-cedrene SOA particles, it is shown that varying the temperature of the particle stream as it enters the DART-MS ionization region can distinguish between specific components with the same molecular mass but different vapor pressures. These results demonstrate the utility of DART-MS for (1) examining reactivity of heterogeneous model systems for atmospheric particles and (2) probing components of SOA particles based on volatility.
Weston, Joseph; Waintal, Xavier
2016-04-01
We report on a "source-sink" algorithm which allows one to calculate time-resolved physical quantities from a general nanoelectronic quantum system (described by an arbitrary time-dependent quadratic Hamiltonian) connected to infinite electrodes. Although mathematically equivalent to the nonequilibrium Green's function formalism, the approach is based on the scattering wave functions of the system. It amounts to solving a set of generalized Schrödinger equations that include an additional "source" term (coming from the time-dependent perturbation) and an absorbing "sink" term (the electrodes). The algorithm execution time scales linearly with both system size and simulation time, allowing one to simulate large systems (currently around 106 degrees of freedom) and/or large times (currently around 105 times the smallest time scale of the system). As an application we calculate the current-voltage characteristics of a Josephson junction for both short and long junctions, and recover the multiple Andreev reflection physics. We also discuss two intrinsically time-dependent situations: the relaxation time of a Josephson junction after a quench of the voltage bias, and the propagation of voltage pulses through a Josephson junction. In the case of a ballistic, long Josephson junction, we predict that a fast voltage pulse creates an oscillatory current whose frequency is controlled by the Thouless energy of the normal part. A similar effect is found for short junctions; a voltage pulse produces an oscillating current which, in the absence of electromagnetic environment, does not relax.
Cosmological special relativity the large scale structure of space, time and velocity
Carmeli, Moshe
2002-01-01
This book presents Einstein's theory of space and time in detail, and describes the large-scale structure of space, time and velocity as a new cosmological special relativity. A cosmological Lorentz-like transformation, which relates events at different cosmic times, is derived and applied. A new law of addition of cosmic times is obtained, and the inflation of the space at the early universe is derived, both from the cosmological transformation. The relationship between cosmic velocity, acceleration and distances is given. In the appendices gravitation is added in the form of a cosmological g
Cosmological special relativity the large scale structure of space, time and velocity
Carmeli, Moshe
1997-01-01
This book deals with special relativity theory and its application to cosmology. It presents Einstein's theory of space and time in detail, and describes the large scale structure of space, time and velocity as a new cosmological special relativity. A cosmological Lorentz-like transformation, which relates events at different cosmic times, is derived and applied. A new law of addition of cosmic times is obtained, and the inflation of the space at the early universe is derived, both from the cosmological transformation. The book will be of interest to cosmologists, astrophysicists, theoretical
Time-scale effects on the gain-loss asymmetry in stock indices
Sándor, Bulcsú
2016-01-01
The gain-loss asymmetry, observed in the inverse statistics of stock indices is present for logarithmic return levels that are over $2\\%$, and it is the result of the non-Pearson type auto-correlations in the index. These non-Pearson type correlations can be viewed also as functionally dependent daily volatilities, extending for a finite time interval. A generalized time-window shuffling method is used to show the existence of such auto-correlations. Their characteristic time-scale proves to be smaller (less than $25$ trading days) than what was previously believed. It is also found that this characteristic time-scale has decreased with the appearance of program trading in the stock market transactions. Connections with the leverage effect are also established.
Time-scale effects on the gain-loss asymmetry in stock indices
Sándor, Bulcsú; Simonsen, Ingve; Nagy, Bálint Zsolt; Néda, Zoltán
2016-08-01
The gain-loss asymmetry, observed in the inverse statistics of stock indices is present for logarithmic return levels that are over 2 % , and it is the result of the non-Pearson-type autocorrelations in the index. These non-Pearson-type correlations can be viewed also as functionally dependent daily volatilities, extending for a finite time interval. A generalized time-window shuffling method is used to show the existence of such autocorrelations. Their characteristic time scale proves to be smaller (less than 25 trading days) than what was previously believed. It is also found that this characteristic time scale has decreased with the appearance of program trading in the stock market transactions. Connections with the leverage effect are also established.
Linking Time and Space Scales in Distributed Hydrological Modelling - a case study for the VIC model
Melsen, Lieke; Teuling, Adriaan; Torfs, Paul; Zappa, Massimiliano; Mizukami, Naoki; Clark, Martyn; Uijlenhoet, Remko
2015-04-01
One of the famous paradoxes of the Greek philosopher Zeno of Elea (~450 BC) is the one with the arrow: If one shoots an arrow, and cuts its motion into such small time steps that at every step the arrow is standing still, the arrow is motionless, because a concatenation of non-moving parts does not create motion. Nowadays, this reasoning can be refuted easily, because we know that motion is a change in space over time, which thus by definition depends on both time and space. If one disregards time by cutting it into infinite small steps, motion is also excluded. This example shows that time and space are linked and therefore hard to evaluate separately. As hydrologists we want to understand and predict the motion of water, which means we have to look both in space and in time. In hydrological models we can account for space by using spatially explicit models. With increasing computational power and increased data availability from e.g. satellites, it has become easier to apply models at a higher spatial resolution. Increasing the resolution of hydrological models is also labelled as one of the 'Grand Challenges' in hydrology by Wood et al. (2011) and Bierkens et al. (2014), who call for global modelling at hyperresolution (~1 km and smaller). A literature survey on 242 peer-viewed articles in which the Variable Infiltration Capacity (VIC) model was used, showed that the spatial resolution at which the model is applied has decreased over the past 17 years: From 0.5 to 2 degrees when the model was just developed, to 1/8 and even 1/32 degree nowadays. On the other hand the literature survey showed that the time step at which the model is calibrated and/or validated remained the same over the last 17 years; mainly daily or monthly. Klemeš (1983) stresses the fact that space and time scales are connected, and therefore downscaling the spatial scale would also imply downscaling of the temporal scale. Is it worth the effort of downscaling your model from 1 degree to 1
Simply and multiply scaled diffusion limits for continuous time random walks
Gorenflo, Rudolf [Erstes Mathematisches Institut, Freie Universitaet Berlin, Arnimallee 3, D-14195 Berlin (Germany); Mainardi, Francesco [Dipartimento di Fisica, Universita di Bologna and INFN, Via Irnerio 46, I-40126 Bologna (Italy)
2005-01-01
First a survey is presented on how space-time fractional diffusion processes can be obtained by well-scaled limiting from continuous time random walks under the sole assumption of asymptotic power laws (with appropriate exponents for the tail behaviour of waiting times and jumps). The spatial operator in the limiting pseudo-differential equation is the inverse of a general Riesz-Feller potential operator. The analysis is carried out via the transforms of Fourier and Laplace. Then mixtures of waiting time distributions, likewise of jump distributions, are considered, and it is shown that correct multiple scaling in the limit yields diffusion equations with distributed order fractional derivatives (fractional operators being replaced by integrals over such ones, with the order of differentiation as variable of integration). It is outlined how in this way super-fast and super-slow diffusion can be modelled.
Scaling relation between earthquake magnitude and the departure time from P wave similar growth
Noda, Shunta; Ellsworth, William L.
2016-01-01
We introduce a new scaling relation between earthquake magnitude (M) and a characteristic of initial P wave displacement. By examining Japanese K-NET data averaged in bins partitioned by Mw and hypocentral distance, we demonstrate that the P wave displacement briefly displays similar growth at the onset of rupture and that the departure time (Tdp), which is defined as the time of departure from similarity of the absolute displacement after applying a band-pass filter, correlates with the final M in a range of 4.5 ≤ Mw ≤ 7. The scaling relation between Mw and Tdp implies that useful information on the final M can be derived while the event is still in progress because Tdp occurs before the completion of rupture. We conclude that the scaling relation is important not only for earthquake early warning but also for the source physics of earthquakes.
Climatic changes on millennial time scales--Evidence from a high-resolution loess record
任剑璋; 丁仲礼; 刘东生; 孙继敏; 周晓权
1996-01-01
Studies on a high resolution loess section in Huining County reveal that the behavior of climate shows high instability during the last glaciation. Results reflect that climate in Loess Plateau oscillates on millennial time scales during the last glacial period. These can be teleconnected with the records of Dansgaard-Oeschger cycles and Heinrich events in high latitudes. Results also demonstrate that variations in the intensity of wind regime on the Loess Plateau have a close correlation with the changes of global ice sheets volume. All these suggest that two-level fordngs may drive climate changes in central Asia. The first level is the volume changes of ice sheets and the second level with short time scales is superimposed upon the first level on a nearly global scale.
A scale dependent black hole in three-dimensional space-time
Koch, Benjamin; Rincón, Ángel
2016-01-01
Scale dependence at the level of the effective action is a generic result of quantum field theory. Allowing for scale dependence of the gravitational couplings leads to a generalization of the corresponding field equations. In this work, those equations are solved by imposing the "null energy condition" in three-dimensional space time with stationary spherical symmetry. The constants of integration are given in terms of the classical BTZ parameters plus one additional constant, that parametrizes the strength of the scale dependence. The properties such as asymptotics, horizon structure, and thermodynamics are discussed. It is found that the black hole entropy shows a remarkable transition from the usual "area~law" to an "area~$\\times$~radius" law.
Multiple dynamical time-scales in networks with hierarchically nested modular organization
Sitabhra Sinha; Swarup Poria
2011-11-01
Many natural and engineered complex networks have intricate mesoscopic organization, e.g., the clustering of the constituent nodes into several communities or modules. Often, such modularity is manifested at several different hierarchical levels, where the clusters deﬁned at one level appear as elementary entities at the next higher level. Using a simple model of a hierarchical modular network, we show that such a topological structure gives rise to characteristic time-scale separation between dynamics occurring at different levels of the hierarchy. This generalizes our earlier result for simple modular networks, where fast intramodular and slow intermodular processes were clearly distinguished. Investigating the process of synchronization of oscillators in a hierarchical modular network, we show the existence of as many distinct time-scales as there are hierarchical levels in the system. This suggests a possible functional role of such mesoscopic organization principle in natural systems, viz., in the dynamical separation of events occurring at different spatial scales.
Venkatachari, Balaji Shankar; Streett, Craig L.; Chang, Chau-Lyan; Friedlander, David J.; Wang, Xiao-Yen; Chang, Sin-Chung
2016-01-01
Despite decades of development of unstructured mesh methods, high-fidelity time-accurate simulations are still predominantly carried out on structured, or unstructured hexahedral meshes by using high-order finite-difference, weighted essentially non-oscillatory (WENO), or hybrid schemes formed by their combinations. In this work, the space-time conservation element solution element (CESE) method is used to simulate several flow problems including supersonic jet/shock interaction and its impact on launch vehicle acoustics, and direct numerical simulations of turbulent flows using tetrahedral meshes. This paper provides a status report for the continuing development of the space-time conservation element solution element (CESE) numerical and software framework under the Revolutionary Computational Aerosciences (RCA) project. Solution accuracy and large-scale parallel performance of the numerical framework is assessed with the goal of providing a viable paradigm for future high-fidelity flow physics simulations.
Minazzoli, Olivier; Chauvineau, Bertrand
2011-04-01
In a recent paper (Minazzoli and Chauvineau 2009 Phys. Rev. D 79 084027), motivated by forthcoming space experiments involving propagation of light in the solar system, we have proposed an extension of the IAU metric equations at the c-4 level in general relativity. However, scalar-tensor theories may induce corrections numerically comparable to the c-4 general relativistic terms. Accordingly, one first proposes in this paper an extension of Minazzoli and Chauvineau (2009) to the scalar-tensor case. The case of a hierarchized system (such as the solar system) is emphasized. In this case, the relevant metric solution is proposed. Then, the corresponding isotropic geodesic solution relevant for distance measurements and time transfers in the inner solar system is given in explicit form.
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]).
Kearney, Brian D; Pell, Rebecca J; Byrne, Phillip G; Reina, Richard D
2014-12-01
Salinity in affected freshwater ecosystems fluctuates with seasonal rainfall, tidal flux, rates of evaporation, chemical runoff and the influence of secondary salinization. Environmental stressors such as salinity can have lasting effects on anuran development, yet little is known about the effects of fluctuating salinity on tadpole ontogeny or the effects of differing magnitudes of salinity exposure, as would occur in natural wetland systems. We examined how salinity fluctuations affected survival, growth and development of Litoria ewingii by exposing tadpoles to a range of salinity concentrations (5.6-10.85 ppt) at three different stages of development (hind limb-bud formation; toe differentiation and forearm development). We also investigated the plasticity of tadpole growth rates in response to non-lethal, transient salinity influxes, specifically examining the capacity for compensatory growth and its relationship to the timing, magnitude or frequency of salinity exposure. Our results show that later-stage tadpoles are more tolerant to elevated salinity than those exposed at a younger age, and that exposure to high salinity later in life suppresses the potential for compensatory growth. Tadpoles exposed to transient low salinity lost less mass during metamorphosis than animals in constant salinity treatments, indicating a possible alternate to compensatory growth. Exposure to near-lethal salinities early in development did not alter tadpole responses to subsequent salinity stress. Our results provide some of the first evidence that both the timing and magnitude of transient environmental stressors can have an effect on anuran development and developmental trade-offs in a stressful environment.
STABILITY ANALYSIS FOR THE LARGE-SCALE SYSTEMS WITH TIME-DELAY
Jingru Qu; Cunchen GAO
2006-01-01
The stability analysis problems were put forward for the large-scale systems with time-delay by using the partial decomposition method. With the stability of the isolated subsystems without time-delay, some sufficient criterions for the asymptotical stability of the whole system were obtained by making a Lyapunov function with the Razumikhin condition and a Lyapunov functional for the retarded type and neutral type, respectively.
Lippiello, Eugenio; Corral, Alvaro; Bottiglieri, Milena; Godano, Cataldo; de Arcangelis, Lucilla
2012-12-01
We present a study of the earthquake intertime distribution D(Δt) for a California catalog in temporal periods of short duration T. We compare experimental results with theoretical predictions and analytical approximate solutions. For the majority of intervals, rescaling intertimes by the average rate leads to collapse of the distributions D(Δt) on a universal curve, whose functional form is well fitted by a Gamma distribution. The remaining intervals, exhibiting a more complex D(Δt), are all characterized by the presence of large shocks. These results can be understood in terms of the relevance of the ratio between the characteristic time c in the Omori law and T: Intervals with Gamma-like behavior are indeed characterized by a vanishing c/T. The above features are also investigated by means of numerical simulations of the Epidemic Type Aftershock Sequence (ETAS) model. This study shows that collapse of D(Δt) is also observed in numerical catalogs; however, the fit with a Gamma distribution is possible only assuming that c depends on the main-shock magnitude m. This result confirms that the dependence of c on m, previously observed for m>6 main shocks, extends also to small m>2.
Short Time-Scale Sensory Coding in S1 during Discrimination of Whisker Vibrotactile Sequences.
McGuire, Leah M; Telian, Gregory; Laboy-Juárez, Keven J; Miyashita, Toshio; Lee, Daniel J; Smith, Katherine A; Feldman, Daniel E
2016-08-01
Rodent whisker input consists of dense microvibration sequences that are often temporally integrated for perceptual discrimination. Whether primary somatosensory cortex (S1) participates in temporal integration is unknown. We trained rats to discriminate whisker impulse sequences that varied in single-impulse kinematics (5-20-ms time scale) and mean speed (150-ms time scale). Rats appeared to use the integrated feature, mean speed, to guide discrimination in this task, consistent with similar prior studies. Despite this, 52% of S1 units, including 73% of units in L4 and L2/3, encoded sequences at fast time scales (≤20 ms, mostly 5-10 ms), accurately reflecting single impulse kinematics. 17% of units, mostly in L5, showed weaker impulse responses and a slow firing rate increase during sequences. However, these units did not effectively integrate whisker impulses, but instead combined weak impulse responses with a distinct, slow signal correlated to behavioral choice. A neural decoder could identify sequences from fast unit spike trains and behavioral choice from slow units. Thus, S1 encoded fast time scale whisker input without substantial temporal integration across whisker impulses.
The time scales of the scattering of energetic protons in interplanetary space
Stevens, G.; Hick, P
1984-01-01
Observations with the directional spectrometer DFH aboard ISEE3 have been used to obtain results on the scattering time scales of energetic protons. Depending on the duration of the scattering process the particle distribution will be subjected to either phase scattering or full scattering. Our analysis of some representative events shows that full scattering is applicable to shock-associated events.
Arctic energy budget in relation to sea ice variability on monthly-to-annual time scales
Krikken, F.; Hazeleger, W.
2015-01-01
The large decrease in Arctic sea ice in recent years has triggered a strong interest in Arctic sea ice predictions on seasonal-to-decadal time scales. Hence, it is important to understand physical processes that provide enhanced predictability beyond persistence of sea ice anomalies. This study
Periodic Solutions for a Class of Singular Hamiltonian Systems on Time Scales
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.
Time scale of scour around a pile in combined waves and current
Petersen, Thor Ugelvig; Sumer, B. Mutlu; Fredsøe, Jørgen
The time scale of the scour process around a circular vertical pile is studied in combined waves and current. A series of tests were carried out in a flume with pile diameters 40 mm and 75 mm, in both steady current, waves and combined waves and current. In the combined wave and current flow regime...
A multiple time-scale model for TCP bandwidth sharing under user heterogeneity
Abendroth, D.; Berg, J.L. van den; Mandjes, M.
2005-01-01
Building on the vast body of existing TCP models, we develop a novel versatile model that explicitly captures user heterogeneity, and takes into consideration dynamics at both the packet level and the flow level. It is described how the resulting multiple time-scale model can be numerically evaluate
Almost Periodic Solutions to Dynamic Equations on Time Scales and Applications
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.
Arctic energy budget in relation to sea ice variability on monthly-to-annual time scales
Krikken, F.; Hazeleger, W.
2015-01-01
The large decrease in Arctic sea ice in recent years has triggered a strong interest in Arctic sea ice predictions on seasonal-to-decadal time scales. Hence, it is important to understand physical processes that provide enhanced predictability beyond persistence of sea ice anomalies. This study anal
Coarse-Grained Modeling of Genetic Circuits as a Function of the Inherent Time Scales
Labavic, Darka; Hildegard, Wolfhard Janke; Meyer-Ortmanns,
2012-01-01
From a coarse-grained perspective the motif of a self-activating species, activating a second species which acts as its own repressor, is widely found in biological systems, in particular in genetic systems with inherent oscillatory behavior. Here we consider a specific realization of this motif as a genetic circuit, in which genes are described as directly producing proteins, leaving out the intermediate step of mRNA production. We focus on the effect that inherent time scales on the underlying fine-grained scale can have on the bifurcation patterns on a coarser scale in time. Time scales are set by the binding and unbinding rates of the transcription factors to the promoter regions of the genes. Depending on the ratio of these rates to the decay times of the proteins, the appropriate averaging procedure for obtaining a coarse-grained description changes and leads to sets of deterministic equations, which differ in their bifurcation structure. In particular the desired intermediate range of regular limit cyc...
Time scales: from Nabla calculus to Delta calculus and vice versa via duality
Caputo, M. Cristina
2009-01-01
In this note we show how one can obtain results from the nabla calculus from results on the delta calculus and vice versa via a duality argument. We provide applications of the main results to the calculus of variations on time scales.
DIRECTIONAL DERIVATIVE OF VECTOR FIELD AND REGULAR CURVES ON TIME SCALES
Emin (O)zyilmaz
2006-01-01
The general idea in this paper is to study curves of the parametric equations where the parameter varies in a so-called time scale, which may be an arbitrary closed subset of the set of all real numbers. We introduce the directional derivative according to the vector fields.
ASYMPTOTIC BEHAVIOR OF SOLUTIONS TO SECOND ORDER IMPULSIVE DIFFERENTIAL EQUATION ON TIME SCALES
无
2011-01-01
In this paper,we investigate a second order impulsive differential equation on time scales.Sufficient conditions are given to guarantee that the solutions tend to zero.The notable effect of impulse upon the asymptotic behavior of solutions is stressed in this paper.At last,we illustrate our results with two examples.
Time scales: from Nabla calculus to Delta calculus and vice versa via duality
Caputo, M. Cristina
2009-01-01
In this note we show how one can obtain results from the nabla calculus from results on the delta calculus and vice versa via a duality argument. We provide applications of the main results to the calculus of variations on time scales.
Labour productivity, economies of scale and opening time in large retail establishments
A.R. Thurik (Roy)
1984-01-01
textabstractDifferences in labour productivity are dealt with for large French retail establishments. Influences of scale, weekly opening time, assortment composition, wage rate and share of counter service are considered. The relationship used is a result of analyses in the field of small retail es
A limit set trichotomy for order-preserving systems on time scales
Christian Poetzsche
2004-04-01
Full Text Available In this paper we derive a limit set trichotomy for abstract order-preserving 2-parameter semiflows in normal cones of strongly ordered Banach spaces. Additionally, to provide an example, Muller's theorem is generalized to dynamic equations on arbitrary time scales and applied to a model from population dynamics.
OSCILLATION FOR NONLINEAR SECOND-ORDER DYNAMIC EQUATIONS ON TIME SCALES
无
2008-01-01
Through the use of generalized Riccati transformation techniques, we establish some oscillation criteria for one type of nonlinear dynamic equation on time scales. Several examples, including a semilinear dynamic equation and a nonlinear Emden-Fowler dynamic equation, are also given to illustrate these criteria and to improve the results obtained in some references.
Hardy inequality on time scales and its application to half-linear dynamic equations
Řehák Pavel
2005-01-01
Full Text Available A time-scale version of the Hardy inequality is presented, which unifies and extends well-known Hardy inequalities in the continuous and in the discrete setting. An application in the oscillation theory of half-linear dynamic equations is given.
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.
Fission time-scale from the measurement of pre-scission light particles and -ray multiplicities
K Ramachandran; A Chatterjee; A Navin; K Mahata; A Shrivastava; V Tripathi; S Kailas; V Nanal; R G Pillay; A Saxena; R G Thomas; D R Chakrabarty; V M Datar; Suresh Kumar; P K Sahu
2015-08-01
An overview of the experimental result on simultaneous measurement of pre-scission neutron, proton, -particle and GDR -ray multiplicities for the reaction 28Si+175Lu at 159 MeV using the BARC–TIFR Pelletron–LINAC accelerator facility is given. The data were analysed using deformation-dependent particle transmission coefficients, binding energies and level densities which are incorporated in the code JOANNE2 to extract fission time-scales and mean deformation of the saddle-to-scission emitter. The neutron, light charged particle and GDR -ray multiplicity data could be explained consistently. The emission of neutrons seems to be favoured towards larger deformation as compared to charged particles. The pre-saddle time-scale is deduced as (0–2) × 10−21 s whereas the saddle-to-scission time-scale is (36–39) × 10−21 s. The total fission time-scale is deduced as (36–41) × 10−21 s.
Improving Building Performance at Urban Scale with a Framework for Real-time Data Sharing
Pang, Xiufeng; Hong, Tianzhen; Piette, Mary Ann
2013-06-03
This paper describes work in progress toward an urban-scale system aiming to reduce energy use in neighboring buildings by providing three components: a database for accessing past and present weather data from high quality weather stations; a network for communicating energy-saving strategies between building owners; and a set of modeling tools for real-time building energy simulation.
POSITIVE SOLUTIONS FOR p-LAPLACIAN DYNAMIC EQUATIONS ON TIME SCALES
Geng Fengjie; Zhu Deming; Li Hongzhi
2007-01-01
The three-point boundary value problems of p-Laplacian dynamic equations on time scales are investigated. By using Krasnosel'skii's fixed-point theorem and fixed-point index theorem, criteria are achieved for the existence of at least one, two or 2n positive solutions.Furthermore, some examples are included to illustrate the main theorems.
Modeling heat dominated electric breakdown in air, with adaptivity to electron or ion time scales
A. Agnihotri (Ashutosh); W. Hundsdorfer (Willem); U. Ebert (Ute)
2017-01-01
textabstractWe model heat dominated electrical breakdown in air in a short planar gap. We couple the discharge dynamics in fluid approximation with the hydrodynamic motion of the air heated by the discharge. To be computationally efficient, we derive a reduced model on the ion time scale, and we
Mass action realizations of reaction kinetic system models on various time scales
Hangos, K M; Szederkenyi, G, E-mail: hangos@scl.sztaki.hu, E-mail: szeder@scl.sztaki.hu [Process Control Research Group, Computer and Automation Reseach Institute, Kende u. 13-17, H-1111 Budapest (Hungary)
2011-01-01
Complex chemical reaction networks often exhibit different dynamic behaviour on different time scales. A combined approach is proposed in this work for determining physically meaningful mass action realizations of complex chemical reaction networks that describe its dynamic behaviour on different time scales. This is achieved by appropriately reducing the detailed overall mass action kinetic scheme using quasi steady state assumptions fit to the particular time scale, and then searching for an optimal realization using mixed integer linear programing. Furthermore, the relationship between the properties (reversibility, deficiency, stability) of the obtained realizations of the same system on different time scales are also investigated and related to the same properties of the detailed overall model. It is shown that the reduced models obtained by quasi steady state assumptions may show exotic nonlinear behaviour, such as oscillations, when the original detailed is globally asymptotically stable. The proposed methods are illustrated by using a simple Michaelis-Menten type reaction kinetic example. The simplified versions of the well known Brusselator model have also been investigated and presented as a case study.
Existence of Solutions for Nonlinear Four-Point -Laplacian Boundary Value Problems on Time Scales
Topal SGulsan
2009-01-01
Full Text Available We are concerned with proving the existence of positive solutions of a nonlinear second-order four-point boundary value problem with a -Laplacian operator on time scales. The proofs are based on the fixed point theorems concerning cones in a Banach space. Existence result for -Laplacian boundary value problem is also given by the monotone method.
Zhang, Jianlei; Weissing, Franz J.; Cao, Ming
2016-09-01
A commonly used assumption in evolutionary game theory is that natural selection acts on individuals in the same time scale; e.g., players use the same frequency to update their strategies. Variation in learning rates within populations suggests that evolutionary game theory may not necessarily be restricted to uniform time scales associated with the game interaction and strategy adaption evolution. In this study, we remove this restricting assumption by dividing the population into fast and slow groups according to the players' strategy updating frequencies and investigate how different strategy compositions of one group influence the evolutionary outcome of the other's fixation probabilities of strategies within its own group. Analytical analysis and numerical calculations are performed to study the evolutionary dynamics of strategies in typical classes of two-player games (prisoner's dilemma game, snowdrift game, and stag-hunt game). The introduction of the heterogeneity in strategy-update time scales leads to substantial changes in the evolution dynamics of strategies. We provide an approximation formula for the fixation probability of mutant types in finite populations and study the outcome of strategy evolution under the weak selection. We find that although heterogeneity in time scales makes the collective evolutionary dynamics more complicated, the possible long-run evolutionary outcome can be effectively predicted under technical assumptions when knowing the population composition and payoff parameters.
Charting the Transient Radio Sky on Sub-Second Time-Scales with LOFAR
Hessels, J.W.T.
2012-01-01
The LOw Frequency ARray (LOFAR) is a radio interferometric telescope that promises to open a largely unexplored window on transient sources in the "radio sky", from time-scales of nanoseconds to years. An important aspect of this will be the study of radio-emitting neutron stars in their various inc
Anti-control of chaos of single time-scale brushless DC motor.
Ge, Zheng-Ming; Chang, Ching-Ming; Chen, Yen-Sheng
2006-09-15
Anti-control of chaos of single time-scale brushless DC motors is studied in this paper. In order to analyse a variety of periodic and chaotic phenomena, we employ several numerical techniques such as phase portraits, bifurcation diagrams and Lyapunov exponents. Anti-control of chaos can be achieved by adding an external constant term or an external periodic term.