Late time solution for interacting scalar in accelerating spaces
Prokopec, Tomislav
2015-01-01
We consider stochastic inflation in an interacting scalar field in spatially homogeneous accelerating space-times with a constant principal slow roll parameter $\\epsilon$. We show that, if the scalar potential is scale invariant (which is the case when scalar contains quartic self-interaction and couples non-minimally to gravity), the late-time solution on accelerating FLRW spaces can be described by a probability distribution function (PDF) $\\rho$ which is a function of $\\varphi/H$ only, where $\\varphi=\\varphi(\\vec x)$ is the scalar field and $H=H(t)$ denotes the Hubble parameter. We give explicit late-time solutions for $\\rho\\rightarrow \\rho_\\infty(\\varphi/H)$, and thereby find the order $\\epsilon$ corrections to the Starobinsky-Yokoyama result. This PDF can then be used to calculate e.g. various $n-$point functions of the (self-interacting) scalar field, which are valid at late times in arbitrary accelerating space-times with $\\epsilon=$ constant.
Electroosmotic fluid motion and late-time solute transport at non-negligible zeta potentials
Energy Technology Data Exchange (ETDEWEB)
S. K. Griffiths; R. H. Nilson
1999-12-01
Analytical and numerical methods are employed to determine the electric potential, fluid velocity and late-time solute distribution for electroosmotic flow in a tube and channel when the zeta potential is not small. The electric potential and fluid velocity are in general obtained by numerical means. In addition, new analytical solutions are presented for the velocity in a tube and channel in the extremes of large and small Debye layer thickness. The electroosmotic fluid velocity is used to analyze late-time transport of a neutral non-reacting solute. Zeroth and first-order solutions describing axial variation of the solute concentration are determined analytically. The resulting expressions contain eigenvalues representing the dispersion and skewness of the axial concentration profiles. These eigenvalues and the functions describing transverse variation of the concentration field are determined numerically using a shooting technique. Results are presented for both tube and channel geometries over a wide range of the normalized Debye layer thickness and zeta potential. Simple analytical approximations to the eigenvalues are also provided for the limiting cases of large and small values of the Debye layer thickness. The methodology developed here for electroosmotic flow is also applied to the Taylor problem of late-time transport and dispersion in pressure-driven flows.
Energy Technology Data Exchange (ETDEWEB)
Shabani, Hamid [University of Sistan and Baluchestan, Physics Department, Faculty of Sciences, Zahedan (Iran, Islamic Republic of); Ziaie, Amir Hadi [Islamic Azad University, Department of Physics, Kahnooj Branch, Kerman (Iran, Islamic Republic of)
2017-05-15
Very recently, Josset and Perez (Phys. Rev. Lett. 118:021102, 2017) have shown that a violation of the energy-momentum tensor (EMT) could result in an accelerated expansion state via the appearance of an effective cosmological constant, in the context of unimodular gravity. Inspired by this outcome, in this paper we investigate cosmological consequences of a violation of the EMT conservation in a particular class of f(R,T) gravity when only the pressure-less fluid is present. In this respect, we focus on the late time solutions of models of the type f(R,T) = R + βΛ(-T). As the first task, we study the solutions when the conservation of EMT is respected, and then we proceed with those in which violation occurs. We have found, provided that the EMT conservation is violated, that there generally exist two accelerated expansion solutions of which the stability properties depend on the underlying model. More exactly, we obtain a dark energy solution for which the effective equation of state depends on the model parameters and a de Sitter solution. We present a method to parametrize the Λ(-T) function, which is useful in a dynamical system approach and has been employed in the model. Also, we discuss the cosmological solutions for models with Λ(-T) = 8πG(-T){sup α} in the presence of ultra-relativistic matter. (orig.)
Shabani, Hamid; Ziaie, Amir Hadi
2017-05-01
Very recently, Josset and Perez (Phys. Rev. Lett. 118:021102, 2017) have shown that a violation of the energy-momentum tensor ( EMT) could result in an accelerated expansion state via the appearance of an effective cosmological constant, in the context of unimodular gravity. Inspired by this outcome, in this paper we investigate cosmological consequences of a violation of the EMT conservation in a particular class of f(R,T) gravity when only the pressure-less fluid is present. In this respect, we focus on the late time solutions of models of the type f(R,T)=R+β Λ (-T). As the first task, we study the solutions when the conservation of EMT is respected, and then we proceed with those in which violation occurs. We have found, provided that the EMT conservation is violated, that there generally exist two accelerated expansion solutions of which the stability properties depend on the underlying model. More exactly, we obtain a dark energy solution for which the effective equation of state depends on the model parameters and a de Sitter solution. We present a method to parametrize the Λ (-T) function, which is useful in a dynamical system approach and has been employed in the model. Also, we discuss the cosmological solutions for models with Λ (-T)=8π G(-T)^{α } in the presence of ultra-relativistic matter.
Late-time cosmological phase transitions
Energy Technology Data Exchange (ETDEWEB)
Schramm, D.N. (Chicago Univ., IL (USA) Fermi National Accelerator Lab., Batavia, IL (USA))
1990-11-01
It is shown that the potential galaxy formation and large-scale structure problems of objects existing at high redshifts (Z {approx gt} 5), structures existing on scales of 100M pc as well as velocity flows on such scales, and minimal microwave anisotropies ({Delta}T/T) {approx lt} 10{sup {minus}5} can be solved if the seeds needed to generate structure form in a vacuum phase transition after decoupling. It is argued that the basic physics of such a phase transition is no more exotic than that utilized in the more traditional GUT scale phase transitions, and that, just as in the GUT case, significant random gaussian fluctuations and/or topological defects can form. Scale lengths of {approximately}100M pc for large-scale structure as well as {approximately}1 M pc for galaxy formation occur naturally. Possible support for new physics that might be associated with such a late-time transition comes from the preliminary results of the SAGE solar neutrino experiment, implying neutrino flavor mixing with values similar to those required for a late-time transition. It is also noted that a see-saw model for the neutrino masses might also imply a tau neutrino mass that is an ideal hot dark matter candidate. However, in general either hot or cold dark matter can be consistent with a late-time transition. 47 refs., 2 figs.
Late time tail of wave propagation on curved spacetime
Ching, E S C; Suen, W M; Young, K; Ching, E S C; Leung, P T; Suen, W M; Young, K
1994-01-01
The late time behavior of waves propagating on a general curved spacetime is studied. The late time tail is not necessarily an inverse power of time. Our work extends, places in context, and provides understanding for the known results for the Schwarzschild spacetime. Analytic and numerical results are in excellent agreement.
Late time behavior of cosmological perturbations in a single brane model
Koyama, K
2004-01-01
We present solutions for the late time evolution of cosmological tensor and scalar perturbations in a single Randall-Sundrum brane world model. Assuming that the bulk is Anti-de Sitter spacetime, the solutions for cosmological perturbations are derived by summing up mode functions in Poincar\\'e coordinate. The junction conditions imposed at the moving brane are solved numerically. The recovery of 4-dimensional Einstein gravity at late times is shown by solving the 5-dimensional perturbations throughout the infinite bulk. We also comment on several possibilities to have deviations from 4-dimensional Einstein gravity.
Late-time spectroscopy of Type Iax Supernovae
Foley, Ryan J.; Jha, Saurabh W.; Pan, Yen-Chen; Zheng, Wei Kang; Bildsten, Lars; Filippenko, Alexei V.; Kasen, Daniel
2016-09-01
We examine the late-time (t ≳ 200 d after peak brightness) spectra of Type Iax supernovae (SNe Iax), a low-luminosity, low-energy class of thermonuclear stellar explosions observationally similar to, but distinct from, Type Ia supernovae. We present new spectra of SN 2014dt, resulting in the most complete late-time spectral sequence of an SN Iax. At late times, SNe Iax have generally similar spectra, all with a similar continuum shape and strong forbidden-line emission. However, there is also significant diversity where some SN Iax spectra display narrow P-Cygni features from permitted lines and a continuum indicative of a photosphere at late times in addition to strong narrow (FWHM 6000 km s-1) forbidden lines, and weak narrow forbidden lines, and some SNe Iax have spectra intermediate to these two varieties. We find that SNe Iax with strong broad forbidden lines are more luminous and have higher velocity ejecta at peak brightness. We estimate blackbody and kinematic radii of the late-time photosphere, finding the latter significantly larger than the former. We propose a two-component model that solves this discrepancy and explains the diversity of the late-time spectra of SNe Iax. In this model, the broad forbidden lines originate from the SN ejecta, while the photosphere, P-Cygni lines, and narrow forbidden lines originate from a wind launched from the remnant of the progenitor white dwarf and is driven by the radioactive decay of newly synthesized material left in the remnant. The relative strength of the two components accounts for the diversity of late-time SN Iax spectra. This model also solves the puzzle of a long-lived photosphere and the slow late-time decline of SNe Iax.
Late time tails in the Kerr spacetime
Gleiser, Reinaldo J; Pullin, Jorge
2008-01-01
Outside a black hole, perturbation fields die off in time as $1/t^n$. For spherical holes $n=2\\ell+3$ where $\\ell$ is the multipole index. In the nonspherical Kerr spacetime there is no coordinate-independent meaning of "multipole," and a common sense viewpoint is to set $\\ell$ to the lowest radiatiable index, although theoretical studies have led to very different claims. Numerical results, to date, have been controversial. Here we show that expansion for small Kerr spin parameter $a$ leads to very definite numerical results confirming previous theoretical analyses.
2D CFT partition functions at late times
Dyer, Ethan; Gur-Ari, Guy
2017-08-01
We consider the late time behavior of the analytically continued partition function Z( β + it) Z( β - it) in holographic 2 d CFTs. This is a probe of information loss in such theories and in their holographic duals. We show that each Virasoro character decays in time, and so information is not restored at the level of individual characters. We identify a universal decaying contribution at late times, and conjecture that it describes the behavior of generic chaotic 2 d CFTs out to times that are exponentially large in the central charge. It was recently suggested that at sufficiently late times one expects a crossover to random matrix behavior. We estimate an upper bound on the crossover time, which suggests that the decay is followed by a parametrically long period of late time growth. Finally, we discuss gravitationally-motivated integrable theories and show how information is restored at late times by a series of characters. This hints at a possible bulk mechanism, where information is restored by an infinite sum over non-perturbative saddles.
2D CFT Partition Functions at Late Times
Dyer, Ethan
2016-01-01
We consider the late time behavior of the analytically continued partition function $Z(\\beta + it) Z(\\beta - it)$ in holographic $2d$ CFTs. This is a probe of information loss in such theories and in their holographic duals. We show that each Virasoro character decays in time, and so information is not restored at the level of individual characters. We identify a universal decaying contribution at late times, and conjecture that it describes the behavior of generic chaotic $2d$ CFTs out to times that are exponentially large in the central charge. It was recently suggested that at sufficiently late times one expects a crossover to random matrix behavior. We estimate an upper bound on the crossover time, which suggests that the decay is followed by a parametrically long period of late time growth. Finally, we discuss integrable theories and show how information is restored at late times by a series of characters. This hints at a possible bulk mechanism, where information is restored by an infinite sum over non-...
Late time accelerated scaling attractors in DGP (Dvali-Gabadadze-Porrati) braneworld
Dutta, Jibitesh; Syiemlieh, Erickson
2016-01-01
In the evolution of late universe, the main source of matter are Dark energy and Dark matter. They are indirectly detected only through their gravitational manifestations. So the possibility of interaction with each other without violating observational restrictions is not ruled out. With this motivation, we investigate the dynamics of DGP braneworld where source of dark energy is a scalar field and it interacts with matter source. Since observation favours phantom case more, we have also studied the dynamics of interacting phantom scalar field. In non interacting DGP braneworld there are no late time accelerated scaling attractors and hence cannot alleviate Coincidence problem. In this paper, we shall show that it is possible to get late time accelerated scaling solutions. The phase space is studied by taking two categories of potentials (Exponential and Non exponential functions). The stability of critical points are examined by taking two specific interactions. The first interaction gives late time acceler...
Late-time Spectroscopy of Type Iax Supernovae
Foley, Ryan J; Pan, Yen-Chen; Zheng, WeiKang; Bildsten, Lars; Filippenko, Alexei V; Kasen, Daniel
2016-01-01
We examine the late-time (t > 200 days after peak brightness) spectra of Type Iax supernovae (SNe Iax), a low-luminosity, low-energy class of thermonuclear stellar explosions observationally similar to, but distinct from, Type Ia supernovae. We present new spectra of SN 2014dt, resulting in the most complete published late-time spectral sequence of a SN Iax. At late times, SNe Iax have generally similar spectra, all with a similar continuum shape and strong forbidden-line emission. However, there is also significant diversity where some late-time SN Iax spectra display narrow P-Cygni features and a continuum indicative of a photosphere in addition to strong narrow forbidden lines, while others have no obvious P-Cygni features, strong broad forbidden lines, and weak narrow forbidden lines. Finally, some SNe Iax have spectra intermediate to these two varieties with weak P-Cygni features and broad/narrow forbidden lines of similar strength. We find that SNe Iax with strong broad forbidden lines also tend to be m...
Amplification of Quantum Meson Modes in the Late Time of the Chiral Phase Transition
Watanabe, K
2007-01-01
We investigate the time evolution of the quantum meson modes in the late time of chiral phase transition. In particular, it is shown that there exists a possible solution to the equation of motion for the quantum meson modes, which reveals a parametric resonance and/or resonance through forced oscillation induced by the small oscillation of the chiral condensate. After that, we demonstrate the unstable regions for the quantum meson modes in both the cases of a uniform and spatially expanding system.
Brane gas cosmology in M-theory late time behavior
Easther, R; Jackson, M G; Kabat, D; Easther, Richard; Greene, Brian R.; Jackson, Mark G.; Kabat, Daniel
2003-01-01
We investigate the late-time behavior of a universe containing a supergravity gas and wrapped 2-branes in the context of M-theory compactified on T^10. The supergravity gas tends to drive uniform expansion, while the branes impede the expansion of the directions about which they are wrapped. Assuming spatial homogeneity, we study the dynamics both numerically and analytically. At late times the radii obey power laws which are determined by the brane wrapping numbers, leading to interesting hierarchies of scale between the wrapped and unwrapped dimensions. The biggest hierarchy that could evolve from an initial thermal fluctuation produces three large unwrapped dimensions. We also study configurations corresponding to string winding, in which the M2-branes are all wrapped around the (small) 11th dimension, and show that this recovers the scenario discussed by Brandenberger and Vafa.
Friedman-Robertson-Walker Models with Late-Time Acceleration
Institute of Scientific and Technical Information of China (English)
Abdussattar; S. R. Prajapati2
2011-01-01
@@ In order to account for the observed cosmic acceleration, a modiGcation of the ansatz for the variation of density in Friedman-Robertson-Walker (FRW) FRW models given by Islam is proposed.The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that of a modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.%In order to account for the observed cosmic acceleration, a modification of the ansatz for the variation of density in Friedman-Robertson-Walker (FRW) FRW models given by Islam is proposed. The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that ora modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.
Hot Dust! Late-Time Infrared Emission From Supernovae
Fox, Ori; Skrutskie, M. F.; Chevalier, R. A.
2010-01-01
Supernovae light curves typically peak and fade in the course of several months. Some supernovae , however, exhibit late-time infrared emission that in some cases can last for several years. These supernovae tend to be of the Type IIn subclass, which is defined by narrow hydrogen and helium emission lines arising from a dense, pre-existing circumstellar medium excited by the supernova radiation. Such a late-time ``IR excess'' with respect to the optical blackbody counterpart typically indicates the presence of warm dust. The origin and heating mechanism of the dust is not, however, always well constrained. In this talk, I will explore several scenarios that explain the observed late-time emission. In particular, I will discuss the case of the Type IIn SN 2005ip, which has displayed an ``IR excess'' for over 3 years. The results allow us to interpret the progenitor system and better understand the late stages of stellar evolution. Much of the data used for this analysis were obtained with TripleSpec, a medium-resolution near-infrared spectrograph located at Apache Point Observatory, NM, and FanCam, a JHK imager located at Fan Mountain Observatory, just outside of Charlottesville, VA. These two instruments were designed, fabricated, built, and commissioned by our instrumentation group at the University of Virginia. I will also spend some time discussing these instruments. I would like to thank the following for financial support of this work throughout my graduate career: NASA GSRP, NSF AAG-0607737, Spitzer PID 50256, Achievement Reward for College Scientists (ARCS), and the Virginia Space Grant Consortium.
Friedman—Robertson—Walker Models with Late-Time Acceleration
Abdussattar; Prajapati, S. R.
2011-02-01
In order to account for the observed cosmic acceleration, a modification of the ansatz for the variation of density in Friedman—Robertson—Walker (FRW) FRW models given by Islam is proposed. The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that of a modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.
Friedmann-Robertson-Walker Models with Late-Time Acceleration
Abdussattar,
2016-01-01
In order to account for the observed cosmic acceleration, a modification of the ansatz for the variation of density in Friedman-Robertson-Walker (FRW) models given by Islam is proposed. The modified ansatz leads to an equation of state which corresponds to that of a variable Chaplygin gas, which in the course of evolution reduces to that of a modified generalized Chaplygin gas (MGCG) and a Chaplygin gas (CG), exhibiting late-time acceleration.
Late time CMB anisotropies constrain mini-charged particles
Energy Technology Data Exchange (ETDEWEB)
Burrage, C.; Redondo, J.; Ringwald, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Jaeckel, J. [Univ. of Durham, Inst. for Particle Physics Phenomenology (United Kingdom)
2009-09-15
Observations of the temperature anisotropies induced as light from the CMB passes through large scale structures in the late universe are a sensitive probe of the interactions of photons in such environments. In extensions of the Standard Model which give rise to mini-charged particles, photons propagating through transverse magnetic fields can be lost to pair production of such particles. Such a decrement in the photon flux would occur as photons from the CMB traverse the magnetic fields of galaxy clusters. Therefore late time CMB anisotropies can be used to constrain the properties of mini- charged particles. We outline how this test is constructed, and present new constraints on mini-charged particles from observations of the Sunyaev-Zel'dovich effect in the Coma cluster. (orig.)
Wave propagation in gravitational systems late time behavior
Ching, E S C; Suen, W M; Young, K
1995-01-01
It is well-known that the dominant late time behavior of waves propagating on a Schwarzschild spacetime is a power-law tail; tails for other spacetimes have also been studied. This paper presents a systematic treatment of the tail phenomenon for a broad class of models via a Green's function formalism and establishes the following. (i) The tail is governed by a cut of the frequency Green's function \\tilde G(\\omega) along the -~Im~\\omega axis, generalizing the Schwarzschild result. (ii) The \\omega dependence of the cut is determined by the asymptotic but not the local structure of space. In particular it is independent of the presence of a horizon, and has the same form for the case of a star as well. (iii) Depending on the spatial asymptotics, the late time decay is not necessarily a power law in time. The Schwarzschild case with a power-law tail is exceptional among the class of the potentials having a logarithmic spatial dependence. (iv) Both the amplitude and the time dependence of the tail for a broad cla...
Unifying inflation with late-time acceleration in BIonic system
Sepehri, Alireza; Setare, Mohammad Reza; Pradhan, Anirudh; Capozziello, Salvatore; Sardar, Iftikar Hossain
2015-01-01
In this research, we propose a new model that allows to unify inflation, deceleration and acceleration phases of expansion history in BIonic system. In this model, in the beginning, there have been $k$ black fundamental strings that transited to the BIon configuration at a corresponding point. At this point, two universe brane and universe antibrane have been created, interacted with each other via one wormhole and inflated. With decreasing temperature, the energy of this wormhole flowed into universe branes and lead to inflation. After a short time, wormhole died, inflation ended and deceleration epoch started. With approaching two universe brane and antibrane together, tachyon was born, grew and caused creation of one new wormhole. At this time, two universe brane and antibrane connected again and late-time acceleration era of the universe began. We compare our model with previous unified phantom model and observational data and obtain some cosmological parameters like temperature in terms of time. We also ...
Nuclear pasta and supernova neutrinos at late times
Horowitz, C J; Caplan, M E; Fischer, T; Lin, Zidu; Newton, W G; O'Connor, E; Roberts, L F
2016-01-01
Nuclear pasta, with nucleons arranged into tubes, sheets, or other complex shapes, is expected in core collapse supernovae (SNe) at just below nuclear density. We calculate the additional opacity from neutrino-pasta coherent scattering using molecular dynamics simulations. We approximately include this opacity in simulations of SNe. We find that pasta slows neutrino diffusion and greatly increases the neutrino signal at late times of 10 or more seconds after stellar core collapse. This signal, for a galactic SN, should be clearly visible in large detectors such as Super-Kamiokande.
Schwarzschild scalar wigs: spectral analysis and late time behavior
Barranco, Juan; Degollado, Juan Carlos; Diez-Tejedor, Alberto; Megevand, Miguel; Alcubierre, Miguel; Nunez, Dario; Sarbach, Olivier
2013-01-01
Using the Green's function representation technique, the late time behavior of localized scalar field distributions on Schwarzschild spacetimes is studied. Assuming arbitrary initial data we perform a spectral analysis, computing the amplitude of each excited quasi-bound mode without the necessity of performing dynamical evolutions. The resulting superposition of modes is compared with a traditional numerical evolution with excellent agreement; therefore, we have an efficient way to determine final black hole wigs. The astrophysical relevance of the quasi-bound modes is discussed in the context of scalar field dark matter models and the axiverse.
A solution to the problem of time
Shlaer, Benjamin
2014-01-01
Despite the severe ultraviolet problems with quantum gravity, infrared phenomena such as eternal inflation and black hole evaporation should enjoy fully quantum mechanical unitary time evolution. Currently this is not possible, the impediment being what is known as the problem of time. Here, we provide a solution by promoting the cosmological constant \\Lambda to a Lagrange multiplier constraining the metric volume element to be manifestly a total derivative. Because \\Lambda appears linearly in the Hamiltonian constraint, it unitarily generates time evolution, yielding a functional Schroedinger equation for gravity. Two pleasant side effects of this construction are that vacuum energy is completely sequestered from the cosmological constant problem, much like in unimodular gravity, and the natural foliation provided by the time variable defines a sensible solution to the measure problem.
Late time cosmic acceleration from natural infrared cutoff?
Gorji, Mohammad Ali
2016-01-01
In this paper, inspired by the ultraviolet deformation of the Friedmann-Lema\\^{\\i}tre-Robertson-Walker geometry in loop quantum cosmology, we formulate an infrared-modified cosmological model. We obtain the associated deformed Friedmann and Raychaudhuri equations and we show that the late time cosmic acceleration can be addressed by the infrared corrections. As a particular example, we applied the setup to the case of matter dominated universe. This model has the same number of parameters as $\\Lambda$CDM, but a dynamical dark energy generates in the matter dominated era at the late time. According to our model, as the universe expands, the energy density of the cold dark matter dilutes and when the Hubble parameter approaches to its minimum, the infrared effects dominate such that the effective equation of state parameter smoothly changes from $w_{_{\\rm eff}}=0$ to $w_{_{\\rm eff}}=-2$. Interestingly and nontrivially, the unstable de Sitter phase with $w_{_{\\rm eff}}=-1$ is corresponding to $\\Omega_m=\\Omega_d ...
Late Time Acceleration From Matter-Curvature Coupling
Zaregonbadi, Raziyeh
2015-01-01
We consider f(R,T) modified theory of gravity, in which, in general, the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar and the trace of the energy-momentum tensor. We mainly focus on a particular model wherein matter is minimally coupled to the geometry in the metric formalism. In this type of the theory, the coupling energy-momentum tensor is not conserved; it determines the appearance of an extra force acting on the particles, and can cause the late time acceleration in the evolution of the universe. To check such a kind of effect, we obtain the corresponding Raychaudhuri dynamical equation that gives the evolution of the kinematic quantities. Then for the chosen model, we derive the behavior of the deceleration parameter, and show that the coupling term can cover the dynamic of the universe in the late time accelerating phase. On the other hand, the curvature of the universe corresponds with the deviation from parallelism in the geodesic motion. Thus, we also scrutinize the...
Time-calibrated Milankovitch cycles for the late Permian.
Wu, Huaichun; Zhang, Shihong; Hinnov, Linda A; Jiang, Ganqing; Feng, Qinglai; Li, Haiyan; Yang, Tianshui
2013-01-01
An important innovation in the geosciences is the astronomical time scale. The astronomical time scale is based on the Milankovitch-forced stratigraphy that has been calibrated to astronomical models of paleoclimate forcing; it is defined for much of Cenozoic-Mesozoic. For the Palaeozoic era, however, astronomical forcing has not been widely explored because of lack of high-precision geochronology or astronomical modelling. Here we report Milankovitch cycles from late Permian (Lopingian) strata at Meishan and Shangsi, South China, time calibrated by recent high-precision U-Pb dating. The evidence extends empirical knowledge of Earth's astronomical parameters before 250 million years ago. Observed obliquity and precession terms support a 22-h length-of-day. The reconstructed astronomical time scale indicates a 7.793-million year duration for the Lopingian epoch, when strong 405-kyr cycles constrain astronomical modelling. This is the first significant advance in defining the Palaeozoic astronomical time scale, anchored to absolute time, bridging the Palaeozoic-Mesozoic transition.
Late time cosmic acceleration from natural infrared cutoff
Directory of Open Access Journals (Sweden)
Mohammad Ali Gorji
2016-09-01
Full Text Available In this paper, inspired by the ultraviolet deformation of the Friedmann–Lemaître–Robertson–Walker geometry in loop quantum cosmology, we formulate an infrared-modified cosmological model. We obtain the associated deformed Friedmann and Raychaudhuri equations and we show that the late time cosmic acceleration can be addressed by the infrared corrections. As a particular example, we applied the setup to the case of matter dominated universe. This model has the same number of parameters as ΛCDM, but a dynamical dark energy generates in the matter dominated era at the late time. According to our model, as the universe expands, the energy density of the cold dark matter dilutes and when the Hubble parameter approaches to its minimum, the infrared effects dominate such that the effective equation of state parameter smoothly changes from weff=0 to weff=−2. Interestingly and nontrivially, the unstable de Sitter phase with weff=−1 is corresponding to Ωm=Ωd=0.5 and the universe crosses the phantom divide from the quintessence phase with weff>−1 and Ωm>Ωd to the phantom phase with weff<−1 and Ωm<Ωd which shows that the model is observationally viable. The results show that the universe finally ends up in a big rip singularity for a finite time proportional to the inverse of the minimum of the Hubble parameter. Moreover, we consider the dynamical stability of the model and we show that the universe starts from the matter dominated era at the past attractor with weff=0 and ends up in a future attractor at the big rip with weff=−2.
Phenomena in late period of seeded precipitation of sodium aluminate solution
Institute of Scientific and Technical Information of China (English)
LI Xiao-bin; FENG Gang-tao; ZHOU Qiu-sheng; PENG Zhi-hong; LIU Gui-hua
2006-01-01
Aiming at seeded precipitation of aluminate solution with high caustic ratio(αk＞2.4), corresponding to the late period of seeded precipitation, the influence of different types of seed on precipitation ratio was explained with respect to solution structure in the interface of seed and the evolution of Al(OH)3 growth units in this layer. The effects of solid content and seed size on agglomeration were determined by calculating the particle number of product. The results imply that the solution structure in the interface of seed imposes a notable significance on the process in the late period of seeded precipitation. Agglomeration still exists in this period. However, the agglomeration bodies break in the case of prolonging precipitation due to the mechanical effect, which results in the increase of particle number.
Late time attractors of some varying Chaplygin gas cosmological models
Khurshudyan, M
2015-01-01
Varying Chaplygin gas is one of the dark fluids actively studied in modern cosmology. It does belong to the group of the fluids which has an explicitly given EoS. From the other hand phase space does contain all possible states of the system. Therefore, phase space analysis of the cosmological models does allow to understand qualitative behavior and estimate required characteristics of the models. Phase space analysis is a convenient approach to study a cosmological model, because we do not need to solve a system of differential equations for a given initial conditions, instead, we need to deal with appropriate algebraic equations. The goal of this paper is to find late time attractors for the cosmological models, where a varying Chaplygin gas is one of the components of the large sale universe. We will pay our attention to some non linear interacting models.
Asphericity in supernova explosions from late-time spectroscopy.
Maeda, Keiichi; Kawabata, Koji; Mazzali, Paolo A; Tanaka, Masaomi; Valenti, Stefano; Nomoto, Ken'ichi; Hattori, Takashi; Deng, Jinsong; Pian, Elena; Taubenberger, Stefan; Iye, Masanori; Matheson, Thomas; Filippenko, Alexei V; Aoki, Kentaro; Kosugi, George; Ohyama, Youichi; Sasaki, Toshiyuki; Takata, Tadafumi
2008-02-29
Core-collapse supernovae (CC-SNe) are the explosions that announce the death of massive stars. Some CC-SNe are linked to long-duration gamma-ray bursts (GRBs) and are highly aspherical. One important question is to what extent asphericity is common to all CC-SNe. Here we present late-time spectra for a number of CC-SNe from stripped-envelope stars and use them to explore any asphericity generated in the inner part of the exploding star, near the site of collapse. A range of oxygen emission-line profiles is observed, including a high incidence of double-peaked profiles, a distinct signature of an aspherical explosion. Our results suggest that all CC-SNe from stripped-envelope stars are aspherical explosions and that SNe accompanied by GRBs exhibit the highest degree of asphericity.
Stellar Mass Assembly of Brightest Cluster Galaxies at Late Times
Inagaki, Takahiro; Huang, Hung-Jin; Hsieh, Bau-Ching; Sugiyama, Naoshi
2014-01-01
Understanding the formation history of brightest cluster galaxies is an important topic in galaxy formation. Utilizing the Planck Sunyaev-Zel'dovich cluster catalog, and applying the Ansatz that the most massive halos at one redshift remain among the most massive ones at a slightly later cosmic epoch, we have constructed cluster samples at redshift z~0.4 and z~0.2 that can be statistically regarded as progenitor-descendant pairs. This allows us to study the stellar mass assembly history of BCGs in these massive clusters at late times, finding the degree of growth between the two epochs is likely at only few percent level, which is far lower compared to the prediction from a state-of-the-art semi-analytic galaxy formation model.
Hot acidic Late Permian seas stifle life in record time
Georgiev, Svetoslav; Stein, Holly J.; Hannah, Judith L.; Bingen, Bernard; Weiss, Hermann M.; Piasecki, Stefan
2011-10-01
The end of Permian time (252-251 Ma) hosts the largest mass extinction in Earth history, yet events heralding this global catastrophe remain intensely disputed. We present a chemostratigraphic marker, the 187Re/ 188Os ratio, which soars to unprecedented levels approaching the Permo-Triassic boundary. These ratios are tied to profound trace element changes and a precise Re-Os time record at 252 Ma preserved in black shales from East Greenland and the mid-Norwegian shelf. Within a 36-meter shale section, an 80-fold increase in Re concentrations (two-fold for Os) signals seawater conditions that became increasingly inhospitable to life. Unwavering initial 187Os/ 188Os ratios of 0.6 preclude mafic volcanism and meteorite impact as the direct cause of Late Permian anoxia. We argue that extraordinarily high 187Re/ 188Os ratios are the hallmark of simultaneously rising ocean temperature and acidity, leading to loss of oxygen and the stifling of life in latest Permian time.
Late time acceleration in a non-commutative model of modified cosmology
Energy Technology Data Exchange (ETDEWEB)
Malekolkalami, B., E-mail: b.malakolkalami@uok.ac.ir [Department of Physics, University of Kurdistan, Pasdaran St., Sanandaj (Iran, Islamic Republic of); Atazadeh, K., E-mail: atazadeh@azaruniv.ac.ir [Department of Physics, Azarbaijan Shahid Madani University, 53714-161, Tabriz (Iran, Islamic Republic of); Vakili, B., E-mail: b-vakili@iauc.ac.ir [Department of Physics, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)
2014-12-12
We investigate the effects of non-commutativity between the position–position, position–momentum and momentum–momentum of a phase space corresponding to a modified cosmological model. We show that the existence of such non-commutativity results in a Moyal Poisson algebra between the phase space variables in which the product law between the functions is of the kind of an α-deformed product. We then transform the variables in such a way that the Poisson brackets between the dynamical variables take the form of a usual Poisson bracket but this time with a noncommutative structure. For a power law expression for the function of the Ricci scalar with which the action of the gravity model is modified, the exact solutions in the commutative and noncommutative cases are presented and compared. In terms of these solutions we address the issue of the late time acceleration in cosmic evolution.
Late time acceleration in a non-commutative model of modified cosmology
Malekolkalami, B.; Atazadeh, K.; Vakili, B.
2014-12-01
We investigate the effects of non-commutativity between the position-position, position-momentum and momentum-momentum of a phase space corresponding to a modified cosmological model. We show that the existence of such non-commutativity results in a Moyal Poisson algebra between the phase space variables in which the product law between the functions is of the kind of an α-deformed product. We then transform the variables in such a way that the Poisson brackets between the dynamical variables take the form of a usual Poisson bracket but this time with a noncommutative structure. For a power law expression for the function of the Ricci scalar with which the action of the gravity model is modified, the exact solutions in the commutative and noncommutative cases are presented and compared. In terms of these solutions we address the issue of the late time acceleration in cosmic evolution.
Late time acceleration in a non-commutative model of modified cosmology
Malekolkalami, B; Vakili, B
2014-01-01
We investigate the effects of noncommutativity between the position-position, position-momentum and momentum-momentum of a phase space corresponding to a modified cosmological model. We show that the existence of such noncommutativity results in a Moyal Poisson algebra between the phase space variables in which the product law between the functions is of the kind of a $\\alpha$-deformed product. We then transform the variables in such a way that the Poisson brackets between the dynamical variables takes the form of a usual Poisson bracket but this time with a noncommutative structure. For a power law expression for the function of the Ricci scalar with which the action of the gravity model is modified, the exact solutions in the commutative and noncommutative cases are presented and compared. In terms of these solutions we address the issue of the late time acceleration in cosmic evolution.
Late time acceleration in a non-commutative model of modified cosmology
Directory of Open Access Journals (Sweden)
B. Malekolkalami
2014-12-01
Full Text Available We investigate the effects of non-commutativity between the position–position, position–momentum and momentum–momentum of a phase space corresponding to a modified cosmological model. We show that the existence of such non-commutativity results in a Moyal Poisson algebra between the phase space variables in which the product law between the functions is of the kind of an α-deformed product. We then transform the variables in such a way that the Poisson brackets between the dynamical variables take the form of a usual Poisson bracket but this time with a noncommutative structure. For a power law expression for the function of the Ricci scalar with which the action of the gravity model is modified, the exact solutions in the commutative and noncommutative cases are presented and compared. In terms of these solutions we address the issue of the late time acceleration in cosmic evolution.
Long-duration superluminous supernovae at late times
Jerkstrand, A; Inserra, C; Nicholl, M; Chen, T -W; Krühler, T; Sollerman, J; Taubenberger, S; Gal-Yam, A; Kankare, E; Maguire, K; Fraser, M; Valenti, S; Sullivan, M; Cartier, R; Young, D R
2016-01-01
We present nebular-phase observations and spectral models of Type Ic superluminous supernovae. LSQ14an and SN 2015bn both display late-time spectra similar to SN 2007bi, and the class shows strong similarity with broad-lined Type Ic SNe such as SN 1998bw. Near-infrared observations of SN 2015bn at +315d show a strong Ca II triplet, O I 9263, O I 1.13 micron and Mg I 1.50 micron, but no strong He, Si, or S emission. The high Ca II NIR/[Ca II] 7291, 7323 ratio of 2 indicates a high electron density of n_e >~ 10^8 cm^{-3}. Spectral models of oxygen-zone emission are investigated to put constraints on the emitting region. Models require M(O) >~ 10 Msun to produce enough [O I] 6300, 6364 luminosity to match observed levels, irrespective of the powering situation and the density. This is an argument against shell collisions from pair-instability pulsations for explaining the powering, as these shells are limited to a few solar masses in published models. The high oxygen-zone mass, supported by high estimated magnes...
The unification of inflation and late-time acceleration in the frame of k-essence
Energy Technology Data Exchange (ETDEWEB)
Saitou, Rio [Nagoya University, Department of Physics, Nagoya (Japan); Nojiri, Shin' ichi [Nagoya University, Department of Physics, Nagoya (Japan); Nagoya University, Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya (Japan)
2011-08-15
By using the formulation of the reconstruction, we explicitly construct models of k-essence, which unify the inflation in the early universe and the late accelerating expansion of the present universe by a single scalar field. Due to the higher derivative terms, the solution describing the unification can be stable in the space of solutions, which makes the restriction for the initial condition relaxed. The higher derivative terms also eliminate tachyon. Therefore we can construct a model describing the time development, which cannot be realized by a usual inflaton or quintessence models of the canonical scalar field due to the instability or the existence of tachyon. We also propose a mechanism of the reheating by the quantum effects coming from the variation of the energy density of the scalar field. (orig.)
Polynomial-time solutions to image segmentation
Energy Technology Data Exchange (ETDEWEB)
Asano, Tetsuo [Osaka Electro-Communication Univ., Neyagawa (Japan); Chen, D.Z. [Notre Dame, South Bend, IN (United States); Katoh, Naoki [Kobe Univ. of Commerce (Japan)
1996-12-31
Separating an object in an image from its background is a central problem (called segmentation) in pattern recognition and computer vision. In this paper, we study the complexity of the segmentation problem, assuming that the object forms a connected region in an intensity image. We show that the optimization problem of separating a connected region in an n-pixel grid is NP-hard under the interclass variance, a criterion that is used in discriminant analysis. More importantly, we consider the basic case in which the object is separated by two x-monotone curves (i.e., the object itself is x-monotone), and present polynomial-time algorithms for computing exact and approximate optimal segmentation. Our main algorithm for exact optimal segmentation by two x-monotone curves runs in O(n{sup 2}) time; this algorithm is based on several techniques such as a parametric optimization formulation, a hand-probing algorithm for the convex hull of an unknown point set, and dynamic programming using fast matrix searching. Our efficient approximation scheme obtains an {epsilon}-approximate solution in O({epsilon}{sup -1} n log L) time, where {epsilon} is any fixed constant with 1 > {epsilon} > 0, and L is the total sum of the absolute values of brightness levels of the image.
The late time structure of high density contrast, single mode Richtmyer-Meshkov flow
Williams, R J R
2016-01-01
We study the late time flow structure of Richtmyer-Meshkov instability. Recent numerical work has suggested a self-similar collapse of the development of this instability at late times, independent of the initial surface profile. Using the form of collapse suggested, we derive an analytic expression for the mass-velocity relation in the spikes, and a global theory for the late time flow structure. We compare these results with fluid dynamical simulation.
Late-time structure of the Bunch-Davies de Sitter wavefunction
Energy Technology Data Exchange (ETDEWEB)
Anninos, Dionysios [Stanford Institute of Theoretical Physics, Stanford University, Stanford (United States); Anous, Tarek [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge (United States); Freedman, Daniel Z. [Stanford Institute of Theoretical Physics, Stanford University, Stanford (United States); Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge (United States); Department of Mathematics, Massachusetts Institute of Technology, Cambridge (United States); Konstantinidis, George [Stanford Institute of Theoretical Physics, Stanford University, Stanford (United States)
2015-11-30
We examine the late time behavior of the Bunch-Davies wavefunction for interacting light fields in a de Sitter background. We use perturbative techniques developed in the framework of AdS/CFT, and analytically continue to compute tree and loop level contributions to the Bunch-Davies wavefunction. We consider self-interacting scalars of general mass, but focus especially on the massless and conformally coupled cases. We show that certain contributions grow logarithmically in conformal time both at tree and loop level. We also consider gauge fields and gravitons. The four-dimensional Fefferman-Graham expansion of classical asymptotically de Sitter solutions is used to show that the wavefunction contains no logarithmic growth in the pure graviton sector at tree level. Finally, assuming a holographic relation between the wavefunction and the partition function of a conformal field theory, we interpret the logarithmic growths in the language of conformal field theory.
Late-time Structure of the Bunch-Davies De Sitter Wavefunction
Anninos, Dionysios; Freedman, Daniel Z; Konstantinidis, George
2014-01-01
We examine the late time behavior of the Bunch-Davies wavefunction for interacting light fields in a de Sitter background. We use perturbative techniques developed in the framework of AdS/CFT, and analytically continue to compute tree and loop level contributions to the Bunch-Davies wavefunction. We consider self-interacting scalars of general mass, but focus especially on the massless and conformally coupled cases. We show that certain contributions grow logarithmically in conformal time both at tree and loop level. We also consider gauge fields and gravitons. The four-dimensional Fefferman-Graham expansion of classical asymptotically de Sitter solutions is used to show that the wavefunction contains no logarithmic growth in the pure graviton sector at tree level. Finally, assuming a holographic relation between the wavefunction and the partition function of a conformal field theory, we interpret the logarithmic growths in the language of conformal field theory.
Late-time quadrupolar gravitational wave power in de Sitter space
Hazboun, Jeffrey
2017-01-01
We have calculated the power emitted by a binary system in a cosmological context modeled by a stress energy source on a de Sitter background. The calculation is based on the quadrupole formula for late-time gravitational waves in de Sitter space put forward by Ashtekar, Bonga and Kesavan. There is little reason to expect, a priori, that the projection operator usually used to find the transverse-traceless components of a tensor in asymptotically flat spaces will accurately characterize the physical degrees of freedom in an asymptotically de Sitter spacetime. Instead we use the differential recipe that is true in general, but cumbersome to solve explicitly. The solution presented is based on a conformally transformed version of the quadrupole moment from a Minkowski spacetime for a stable circular binary. A process for calculating the late time power is presented, which coincides with future null infinity. Progress on time dependent results will also be presented. We will discuss the physicality of these results and compare it to other results for gravitational waves in de Sitter space, including recent results on gravitational wave memory.
Considering Late-Time Acceleration in Some Cosmological Models
Directory of Open Access Journals (Sweden)
S. Davood Sadatian
2013-01-01
Full Text Available We study two cosmological models: a nonminimally coupled scalar field on brane world model and a minimally coupled scalar field on Lorentz invariance violation model. We compare some cosmological results in these scenarios. Also, we consider some types of Rip singularity solution in both models.
Semianalytic Solution of Space-Time Fractional Diffusion Equation
Directory of Open Access Journals (Sweden)
A. Elsaid
2016-01-01
Full Text Available We study the space-time fractional diffusion equation with spatial Riesz-Feller fractional derivative and Caputo fractional time derivative. The continuation of the solution of this fractional equation to the solution of the corresponding integer order equation is proved. The series solution of this problem is obtained via the optimal homotopy analysis method (OHAM. Numerical simulations are presented to validate the method and to show the effect of changing the fractional derivative parameters on the solution behavior.
Sela, Orr
2016-10-01
In this paper, we employ the results of a previous paper on the late-time decay of scalar-field perturbations of an extreme Reissner-Nordstrom black hole, in order to find the late-time decay of coupled electromagnetic and gravitational perturbations of this black hole. We explicitly write the late-time tails of Moncrief's gauge invariant variables and of the perturbations of the metric tensor and the electromagnetic field tensor in the Regge-Wheeler gauge. We discuss some of the consequences of the results and relations to previous works.
Krauss, Lawrence M; Dent, James
2008-05-01
We describe here how the late time behavior of the quantum mechanical decay of unstable states, which is predicted to deviate from an exponential form, may have important cosmological implications. It may increase the likelihood of eternal inflation and may enhance the likelihood of observing a small vacuum energy at late times versus possible late time decay into a large negative energy (anti-de Sitter space) vacuum state. Open questions include the following: How can internal observations made impact upon the wave function of the Universe and hence upon its decay characteristics?
Sela, Orr
2016-01-01
In this paper we employ the results of a previous paper on the late-time decay of scalar-field perturbations of an extreme Reissner-Nordstrom black hole, in order to find the late-time decay of coupled electromagnetic and gravitational perturbations of this black hole. We explicitly write the late-time tails of Moncrief's gauge invariant variables and of the perturbations of the metric tensor and the electromagnetic field tensor in the Regge-Wheeler gauge. We discuss some of the consequences of the results and relations to previous works.
Time-dependent exact solutions of the nonlinear Kompaneets equation
Energy Technology Data Exchange (ETDEWEB)
Ibragimov, N H, E-mail: nib@bth.s [Department of Mathematics and Science, Blekinge Institute of Technology, 371 79 Karlskrona (Sweden)
2010-12-17
Time-dependent exact solutions of the Kompaneets photon diffusion equation are obtained for several approximations of this equation. One of the approximations describes the case when the induced scattering is dominant. In this case, the Kompaneets equation has an additional symmetry which is used for constructing some exact solutions as group invariant solutions. (fast track communication)
Late-time behaviour of the tilted Bianchi type VIh models
Hervik, S.; van den Hoogen, R. J.; Lim, W. C.; Coley, A. A.
2007-08-01
We study tilted perfect fluid cosmological models with a constant equation of state parameter in spatially homogeneous models of Bianchi type VIh using dynamical systems methods and numerical experimentation, with an emphasis on their future asymptotic evolution. We determine all of the equilibrium points of the type VIh state space (which correspond to exact self-similar solutions of the Einstein equations, some of which are new), and their stability is investigated. We find that there are vacuum plane-wave solutions that act as future attractors. In the parameter space, a 'loophole' is shown to exist in which there are no stable equilibrium points. We then show that a Hopf-bifurcation can occur resulting in a stable closed orbit (which we refer to as the Mussel attractor) corresponding to points both inside the loophole and points just outside the loophole; in the former case the closed curves act as late-time attractors while in the latter case these attracting curves will co-exist with attracting equilibrium points. In the special Bianchi type III case, centre manifold theory is required to determine the future attractors. Comprehensive numerical experiments are carried out to complement and confirm the analytical results presented. We note that the Bianchi type VIh case is of particular interest in that it contains many different subcases which exhibit many of the different possible future asymptotic behaviours of Bianchi cosmological models.
Late-time behaviour of the tilted Bianchi type VIh models
Hervik, S; Lim, W C; Coley, A A
2007-01-01
We study tilted perfect fluid cosmological models with a constant equation of state parameter in spatially homogeneous models of Bianchi type VI$_h$ using dynamical systems methods and numerical experimentation, with an emphasis on their future asymptotic evolution. We determine all of the equilibrium points of the type VI$_h$ state space (which correspond to exact self-similar solutions of the Einstein equations, some of which are new), and their stability is investigated. We find that there are vacuum plane-wave solutions that act as future attractors. In the parameter space, a `loophole' is shown to exist in which there are no stable equilibrium points. We then show that a Hopf-bifurcation can occur resulting in a stable closed orbit (which we refer to as the Mussel attractor) corresponding to points both inside the loophole and points just outside the loophole; in the former case the closed curves act as late-time attractors while in the latter case these attracting curves will co-exist with attracting eq...
Part-Time Work: Solution or Trap?
Bolle, Patrick
1997-01-01
Presents some of the benefits and drawbacks of part-time work and describes measures taken to make the most of the former and counteract the latter, taking care to distinguish the individual and national levels. Discusses definitions and methodology, the difficulties involved in making international comparisons, and the relationship between…
Spherically symmetric solution in a space-time with torsion
Farfan, Filemon; Loaiza-Brito, Oscar; Moreno, Claudia; Yakhno, Alexander
2011-01-01
By using the analysis group method, we obtain a new exact evolving and spherically symmetric solution of the Einstein-Cartan equations of motion, corresponding to a space-time threaded with a three-form Kalb-Ramond field strength. The solution describes in its more generic form, a space-time which scalar curvature vanishes for large distances and for large time. In static conditions, it reduces to a classical wormhole solution already reported in literature. In the process we have found evidence towards the construction of more new solutions.
Time and Cosmos: A Zoomorphic Cosmological Monument of Late Antiquity
Directory of Open Access Journals (Sweden)
Nikolay Sivkov
2010-04-01
Full Text Available The protome of the ram from West Bulgaria is a lunisolar calendar ofparapegmatic type from the period of antiquity (2nd–4th century AC, which imparts encoded calendrical, cosmological and cosmogonic information.On the protome there are marked synodic, sidereal, and draconic months; lunar, solar and draconic years, as well as different time periods – seasons and cycles. One of the images on the protome’s body can be interpreted as an image of the Draco constellation around the fixed point of the North Pole in the centre of the ecliptic. The symbols of seven luminaries – the Sun, the Moon and five planets – which were known at the beginning of the first millennium are alsofeatured on the protome.In the context of the monument, the presence of the astronomical concept of the world axis and the centre of the ecliptic means that the creators of the ram’s protome perceived it as an omphalos, the sacred centre of the world, the zoomorphic model of the world mountain and the world tree. The suggestion is confirmed by the structural particularities of the protome, by the images of mythological characters and by scenes of cosmogonic motifs. The given artefact represents the conceptualisation of the world in a generalised, syncretised and interdisciplinary way through the language of astronomy, mythology and calendaristics.In the period of antiquity, time and space were perceived as a united integer and as an endless divine beginning connected with the universe and its divine essence. The calendar is an attempt to comprehend the phenomenon of an infinite and cyclic time and use it in practice during the terrestrial life.
A late time accelerated FRW model with scalar and vector fields via Noether symmetry
Energy Technology Data Exchange (ETDEWEB)
Vakili, Babak, E-mail: b-vakili@iauc.ac.ir
2014-11-10
We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann–Robertson–Walker (FRW) model, a scalar field with potential function V(ϕ) with which the gravity part of the action is minimally coupled and a vector field of its kinetic energy is coupled with the scalar field by a coupling function f(ϕ). Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current, we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology is an accelerated expansion universe for which its expansion is due to the presence of the vector field in the early times, while the scalar field is responsible of its late time expansion.
A late time accelerated FRW model with scalar and vector fields via Noether symmetry
Directory of Open Access Journals (Sweden)
Babak Vakili
2014-11-01
Full Text Available We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann–Robertson–Walker (FRW model, a scalar field with potential function V(ϕ with which the gravity part of the action is minimally coupled and a vector field of its kinetic energy is coupled with the scalar field by a coupling function f(ϕ. Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current, we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology is an accelerated expansion universe for which its expansion is due to the presence of the vector field in the early times, while the scalar field is responsible of its late time expansion.
A late time accelerated FRW model with scalar and vector fields via Noether symmetry
Vakili, Babak
2014-11-01
We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann-Robertson-Walker (FRW) model, a scalar field with potential function V (ϕ) with which the gravity part of the action is minimally coupled and a vector field of its kinetic energy is coupled with the scalar field by a coupling function f (ϕ). Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current, we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology is an accelerated expansion universe for which its expansion is due to the presence of the vector field in the early times, while the scalar field is responsible of its late time expansion.
Late Time Emission of Prompt Fission Gamma Rays
Talou, P; Stetcu, I; Lestone, J P; McKigney, E; Chadwick, M B
2016-01-01
The emission of prompt fission $\\gamma$ rays within a few nanoseconds to a few microseconds following the scission point is studied in the Hauser-Feshbach formalism applied to the deexcitation of primary excited fission fragments. Neutron and $\\gamma$-ray evaporations from fully accelerated fission fragments are calculated in competition at each stage of the decay, and the role of isomers in the fission products, before $\\beta$-decay, is analyzed. The time evolution of the average total $\\gamma$-ray energy, average total $\\gamma$-ray multiplicity, and fragment-specific $\\gamma$-ray spectra, is presented in the case of neutron-induced fission reactions of $^{235}$U and $^{239}$Pu, as well as spontaneous fission of $^{252}$Cf. The production of specific isomeric states is calculated and compared to available experimental data. About 7% of all prompt fission $\\gamma$ rays are predicted to be emitted between 10 nsec and 5 $\\mu$sec following fission, in the case of $^{235}$U and $^{239}$Pu $(n_{\\rm th},f)$ reactio...
Mourelle, Dominique; Prieto, Aldo R.; García-Rodríguez, Felipe
2017-07-01
A detailed palynological record from Laguna Formosa (northeastern campos region, 31°S; 54°W) documents the dynamic balance between grasslands and riparian forests during the late Pleistocene (14,570 to 13,500 cal yr BP) and late Holocene (3280 cal yr BP to the present). Modern pollen-vegetation relationships and the woody pollen dispersal capacity analyses were used to improve the vegetation reconstruction. Grasslands were regionally dominant throughout the record. However, at 14,570 cal yr BP hydrophilous taxa reflect the development of riparian hydrophilous shrublands along freshwater bodies, promoting the fixation of the riverbanks, maintaining shallow, calm and clear water conditions under a relatively wet and not so cool climate. This is the first evidence of woody riparian vegetation development along freshwater bodies for the lowlands of the northern campos during the late glacial period. At 3280 cal yr BP riparian forests consisted of both hydrophilous and mesophilous woody taxa. Since 2270 cal yr BP woody vegetation gradually increased, accompanied by the incorporation of other taxa by 940 cal yr BP, and achieving a composition similar to that of the contemporary time at ca. 540 cal yr BP. The increased woody vegetation since ca. 2270 cal yr BP, and the more frequent and intense flooding events between 1800 and 1200 cal yr BP, could be related to higher precipitation over La Plata Drainage Basin, related with the high ENSO amplitude. In addition, pollen from taxa that currently no longer develops in the study area suggests connections between southern Brazil and Uruguay, and between the campos and the Chaco phytogeographic province.
Central Engine of Late-time X-Ray Flares with Internal Origin
Mu, Hui-Jun; Gu, Wei-Min; Hou, Shu-Jin; Liu, Tong; Lin, Da-Bin; Yi, Tuan; Liang, En-Wei; Lu, Ju-Fu
2016-12-01
This work focuses on a sample of seven extremely late-time X-ray flares with peak time {t}{{p}}\\gt {10}4 {{s}}, among which two flares can be confirmed as the late-time activity of central engine. The main purpose is to investigate the mechanism of such late-time flares based on the internal origin assumption. In the hyper-accreting black hole (BH) scenario, we study the possibility of two well-known mechanisms acting as the central engine to power such X-ray flares, i.e., the neutrino-antineutrino annihilation and the Blandford-Znajek (BZ) process. Our results show that the annihilation luminosity is far below the observational data. Thus, the annihilation mechanism cannot account for such late-time flares. For the BZ process, if the role of outflows is taken into consideration, the inflow mass rate near the horizon will be quite low such that the magnetic field will probably be too weak to power the observed X-ray flares. We therefore argue that, for the late-time flares with internal origin, the central engine is unlikely to be associated with BHs. On the contrary, a fast rotating neutron star with strong bipolar magnetic fields may be responsible for such flares.
Central Engine of Late-Time X-ray Flares with Internal Origin
Mu, Hui-Jun; Hou, Shu-Jin; Liu, Tong; Lin, Da-Bin; Yi, Tuan; Liang, En-Wei; Lu, Ju-Fu
2016-01-01
This work focuses on a sample of seven extremely late-time X-ray flares with peak time $t_{\\rm p} > 10^4 {\\rm s}$, among which two flares can be confirmed as the late-time activity of central engine. The main purpose is to investigate the mechanism of such late-time flares based on the internal origin assumption. In the hyper-accreting black hole (BH) scenario, we study the possibility of two well-known mechanisms as the central engine to power such X-ray flares, i.e., the neutrino-antineutrino annihilation and the Blandford-Znajek (BZ) process. Our results show that the annihilation luminosity is far below the observational data. Thus, the annihilation mechanism cannot account for such late-time flares. For the BZ process, if the role of outflows is taken into consideration, the inflow mass rate near the horizon will be quite low such that the magnetic field will probably be too weak to power the observed X-ray flares. We therefore argue that, for the late-time flares with internal origin, the central engine...
Exact time-localized solutions in Vacuum String Field Theory
Bonora, L; Santos, R J S; Tolla, D D
2004-01-01
We address the problem of finding star algebra projectors that exhibit localized time profiles. We use the double Wick rotation method, starting from an Euclidean (unconventional) lump solution, which is characterized by the Neumann matrix being the conventional one for the continuous spectrum, while the inverse of the conventional one for the discrete spectrum. This is still a solution of the projector equation and we show that, after inverse Wick-rotation, its time profile has the desired localized time dependence. We study it in detail in the low energy regime (field theory limit) and in the extreme high energy regime (tensionless limit) and show its similarities with the rolling tachyon solution.
Aspects of late-time evolution in mimetic F(R) gravity
Oikonomou, V. K.
2016-09-01
We demonstrate how to describe in an unified way early and late-time acceleration in the context of mimetic F(R) gravity. As we show, an exponential F(R) gravity model has appealing features, with regard to unification and we perform an analysis of the late-time evolution. The resulting picture is interesting since in the mimetic case, certain pathologies of some ordinary F(R) models are remedied in a consistent way, owing to the presence of the mimetic potential and the Lagrange multiplier. We quantify the late-time evolution analysis by studying the scaled dark energy density, the dark energy equation of state and the total effective equation of state, and as we show the late-time evolution is crucially affected by the functional form of the F(R) gravity. It is intriguing that the most appealing case corresponds to the exponential F(R) gravity which unifies late- and early-time acceleration. Finally, we study the behavior of the effective gravitational constant and the growth factor, and as we show, significant differences between the mimetic and ordinary F(R) exponential model are spotted in the growth factor.
Aspects of Late-time Evolution in Mimetic $F(R)$ Gravity
Oikonomou, V K
2016-01-01
We demonstrate how to describe in an unified way early and late-time acceleration in the context of mimetic $F(R)$ gravity. As we show, an exponential $F(R)$ gravity model has appealing features, with regard to unification, and we perform an analysis of the late-time evolution. The resulting picture is interesting since in the mimetic case, certain pathologies of some ordinary $F(R)$ models are remedied in a consistent way, owing to the presence of the mimetic potential and the Lagrange multiplier. We quantify the late-time evolution analysis by studying the scaled dark energy density, the dark energy equation of state and the total effective equation of state, and as we show the late-time evolution is crucially affected by the functional form of the $F(R)$ gravity. It is intriguing that the most appealing case corresponds to the exponential $F(R)$ gravity which unifies late and early-time acceleration. Finally, we study the behavior of the effective gravitational constant and the growth factor, and as we sho...
Analytical Solution of the Time Fractional Fokker-Planck Equation
Directory of Open Access Journals (Sweden)
Sutradhar T.
2014-05-01
Full Text Available A nonperturbative approximate analytic solution is derived for the time fractional Fokker-Planck (F-P equation by using Adomian’s Decomposition Method (ADM. The solution is expressed in terms of Mittag- Leffler function. The present method performs extremely well in terms of accuracy, efficiency and simplicity.
Similarity solutions for radiation in time-dependent relativistic flows
Lucy, L B
2004-01-01
Exact analytic solutions are derived for radiation in time-dependent relativistic flows. The flows are spherically-symmetric homologous explosions or implosions of matter with a grey extinction coefficient. The solutions are suitable for testing numerical transfer codes, and this is illustrated for a fully relativistic Monte Carlo code.
2013-01-01
arXiv:1210.8106v2 [gr-qc] 11 Feb 2013 Late Time Acceleration of the 3-Space in a Higher Dimensional Steady State Universe in Dilaton Gravity Özgür Akarsua , b, Tekin Derelia a Department of Physics, Koç University, 34450 Sarıyer, İstanbul, Turkey b Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste, Italy Abstract We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an ar...
Influence of container structures and content solutions on dispensing time of ophthalmic solutions
Directory of Open Access Journals (Sweden)
Keiji Yoshikawa
2010-05-01
Full Text Available Keiji Yoshikawa1, Hiroshi Yamada21Yoshikawa Eye Clinic, Tokyo, Japan; 2Santen Pharmaceutical Co., Ltd., Osaka, JapanPurpose: To investigate the influence of container structures and content solutions on the time of dispensing from eye dropper bottles.Methods: Eye dropper bottle models, solution models (filtrate water/surfactant solution and a dispensing time measuring apparatus were prepared to measure the dispensing time.Results: With filtrate water and pressure thrust load of 0.3 MPa, the dispensing time significantly increased from 1.1 ± 0.5 seconds to 4.6 ± 1.1 seconds depending on the decrease of inner aperture diameters from 0.4 mm to 0.2 mm (P < 0.0001. When using the bottle models with inner aperture diameters of 0.4 mm or larger, the dispensing time became constant. The dispensing time using surfactant solution showed the same tendency as above. When pressure thrust load was large (0.07 MPa, the solution flew out continuously with inner aperture diameters of 0.4 mm or larger and the dispensing time could not be measured. The inner aperture diameter most strongly explained the variation of the dispensing time in both the content solutions in the multiple linear regression analysis (filtrate water: 46%, R2 = 0.462, surfactant solution: 56%, R2 = 0.563.Conclusions: Among content solutions and container structures, the dispensing time was mostly influenced by the diameter of the inner aperture of bottles.Keywords: dispensing time, model eye dropper bottle, model ophthalmic solution, nozzle internal space volume, nozzle inner aperture diameter
Time-periodic solutions of the Benjamin-Ono equation
Energy Technology Data Exchange (ETDEWEB)
Ambrose , D.M.; Wilkening, Jon
2008-04-01
We present a spectrally accurate numerical method for finding non-trivial time-periodic solutions of non-linear partial differential equations. The method is based on minimizing a functional (of the initial condition and the period) that is positive unless the solution is periodic, in which case it is zero. We solve an adjoint PDE to compute the gradient of this functional with respect to the initial condition. We include additional terms in the functional to specify the free parameters, which, in the case of the Benjamin-Ono equation, are the mean, a spatial phase, a temporal phase and the real part of one of the Fourier modes at t = 0. We use our method to study global paths of non-trivial time-periodic solutions connecting stationary and traveling waves of the Benjamin-Ono equation. As a starting guess for each path, we compute periodic solutions of the linearized problem by solving an infinite dimensional eigenvalue problem in closed form. We then use our numerical method to continue these solutions beyond the realm of linear theory until another traveling wave is reached (or until the solution blows up). By experimentation with data fitting, we identify the analytical form of the solutions on the path connecting the one-hump stationary solution to the two-hump traveling wave. We then derive exact formulas for these solutions by explicitly solving the system of ODE's governing the evolution of solitons using the ansatz suggested by the numerical simulations.
Time-Machine Solutions of Einstein's Equations with Electromagnetic Field
Institute of Scientific and Technical Information of China (English)
SHEN Ming; SUN Qing-You
2011-01-01
In this paper we investigate the time-machine problem in the electromagnetic field.Based on a metric which is a more general form of Ori's, we solve the Einstein's equations with the energy-momentum tensors for electromagnetic field, and construct the time-machine solutions, which solve the time machine problem in electromagnetic field.
LEGENDRE SERIES SOLUTIONS FOR TIME-VARIATION DYNAMICS
Institute of Scientific and Technical Information of China (English)
Cao Zhiyuan; Zou Guiping; Tang Shougao
2000-01-01
In this topic, a new approach to the analysis of time-variation dynamics is proposed by use of Legendre series expansion and Legendre integral operator matrix. The theoretical basis for effective solution of time-variation dynamics is therefore established, which is beneficial to further research of time-variation science.
After the Fall: Late-Time Spectroscopy of Type IIP Supernovae
Silverman, Jeffrey M.; Pickett, Stephanie; Craig Wheeler, J.; Filippenko, Alexei V.; Vinkó, József; Marion, G. H.; Bradley Cenko, S.; Chornock, Ryan; Clubb, Kelsey I.; Foley, Ryan J.; Graham, Melissa L.; Kelly, Patrick L.; Matheson, Thomas; Shields, Joseph C.
2017-01-01
Herein we analyse late-time (post-plateau; 103 stars have ejecta with a more physically extended oxygen layer that is well-mixed with the hydrogen layer. In addition, we find a subset of objects with evidence for asymmetric 56Ni ejection, likely bipolar in shape. We also compare our observations to theoretical late-time spectral models of SNe IIP from two separate groups and find moderate-to-good agreement with both sets of models. Our SNe IIP spectra are consistent with models of 12-15 M⊙ progenitor stars having relatively low metallicity (Z ≤ 0.01).
Time Domain Reflectometric and spectroscopic studies on toluene + butyronitrile solution
Karthick, N. K.; Arivazhagan, G.; Kumbharkhane, A. C.; Joshi, Y. S.; Kannan, P. P.
2016-03-01
The dielectric parameters of toluene + butyronitrile solution have been obtained by time domain reflectometry (TDR) technique in the frequency range from 10 MHz to 30 GHz at 298 K. Spectroscopic (FTIR and 13C NMR) studies have also been carried out on the solution and the results of the studies show that neat butyronitrile is self-associative through C-H⋯N contacts and weak intermolecular forces of C-H⋯N and C-H⋯π type are operative in the solution. The obtained dielectric parameters such as Kirkwood correlation factor g, relaxation time τ etc. have been analyzed in view of these weak intermolecular forces. The weak non-covalent interactions between heteromolecules appear to have no influence on the ideality of ɛm vs X2 curve of the solution. Heteromolecular entities with weak intermolecular forces experience larger hindrance leading to longer relaxation time τ.
Translation invariant time-dependent solutions to massive gravity
Energy Technology Data Exchange (ETDEWEB)
Mourad, J.; Steer, D.A., E-mail: mourad@apc.univ-paris7.fr, E-mail: steer@apc.univ-paris7.fr [AstroParticule and Cosmologie (UMR 7164 - APC, Univ Paris Diderot, CNRS/IN2P3, CEA/lrfu, Obs de Paris, Sorbonne Paris Cité, France), 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France)
2013-12-01
Homogeneous time-dependent solutions of massive gravity generalise the plane wave solutions of the linearised Fierz-Pauli equations for a massive spin-two particle, as well as the Kasner solutions of General Relativity. We show that they also allow a clear counting of the degrees of freedom and represent a simplified framework to work out the constraints, the equations of motion and the initial value formulation. We work in the vielbein formulation of massive gravity, find the phase space resulting from the constraints and show that several disconnected sectors of solutions exist some of which are unstable. The initial values determine the sector to which a solution belongs. Classically, the theory is not pathological but quantum mechanically the theory may suffer from instabilities. The latter are not due to an extra ghost-like degree of freedom.
Translation invariant time-dependent solutions to massive gravity
Mourad, J
2013-01-01
Homogeneous time-dependent solutions of massive gravity generalise the plane wave solutions of the linearised Fierz-Pauli equations for a massive spin-two particle, as well as the Kasner solutions of General Relativity. We show that they also allow a clear counting of the degrees of freedom and represent a simplified framework to work out the constraints, the equations of motion and the initial value formulation. We work in the vielbein formulation of massive gravity, find the phase space resulting from the constraints and show that several disconnected sectors of solutions exist some of which are unstable. The initial values determine the sector to which a solution belongs. Classically, the theory is not pathological but quantum mechanically the theory may suffer from instabilities. The latter are not due to an extra ghost-like degree of freedom.
Generating time dependent conformally coupled Einstein-scalar solutions
Sultana, Joseph
2015-07-01
Using the correspondence between a minimally coupled scalar field and an effective stiff perfect fluid with or without a cosmological constant, we present a simple method for generating time dependent Einstein-scalar solutions with a conformally coupled scalar field that has vanishing or non-vanishing potential. This is done by using Bekenstein's transformation on Einstein-scalar solutions with minimally coupled massless scalar fields, and its later generalization by Abreu et al. to massive fields. In particular we obtain two new spherically symmetric time dependent solutions to the coupled system of Einstein's and the conformal scalar field equations, with one of the solutions having a Higgs' type potential for the scalar field, and we study their properties.
Part-Time Faculty and Gerontology Programs: Dilemmas and Solutions
Parrott, Tonya M.; Grabinski, C. Joanne; Silverstein, Nina M.; Spencer, Marian; Takayanagi, Paul W.; Yee-Melichar, Darlene
2007-01-01
This article presents an overview of the use of adjunct faculty generally and within gerontology programs and discusses the benefits, drawbacks and possible solutions for both adjunct faculty and gerontology programs to utilize part-time teaching staff. The benefits reported for being a part-time faculty member include wanting to be in academia…
A parametric LTR solution for discrete-time systems
DEFF Research Database (Denmark)
Niemann, Hans Henrik; Jannerup, Ole Erik
1989-01-01
and the full loop transfer function, is manipulated into a general form involving the target loop transfer matrix and the fundamental recovery matrix. A parametric LTR solution based on the recovery matrix is developed. It is shown that the LQR/LTR (linear quadratic Gaussian/loop transfer recovery) solution......A parametric LTR (loop transfer recovery) solution for discrete-time compensators incorporating filtering observers which achieve exact recovery is presented for both minimum- and non-minimum-phase systems. First the recovery error, which defines the difference between the target loop transfer...
Open EFTs, IR Effects and Late-Time Resummations: Systematic Corrections in Stochastic Inflation
Burgess, C P; Tasinato, G
2015-01-01
Though simple inflationary models describe the CMB well, their corrections are often plagued by infrared effects that obstruct a reliable calculation of late-time behaviour. We adapt to cosmology tools designed to address similar issues in other physical systems with the goal of making reliable late-time inflationary predictions. The main such tool is Open EFTs which reduce in the inflationary case to Stochastic Inflation plus calculable corrections. We apply this to a simple inflationary model that is complicated enough to have dangerous IR behaviour yet simple enough to allow the inference of late-time behaviour. We find corrections to standard Stochastic Inflationary predictions for the noise and drift, and we find these corrections ensure the IR finiteness of both these quantities. The late-time probability distribution, ${\\cal P}(\\phi)$, for super-Hubble field fluctuations are obtained as functions of the noise and drift and so these too are IR finite. We compare our results to other methods (such as lar...
Glavan, D.; Prokopec, T.; van der Woude, D. C.
2015-01-01
We consider the late-time one-loop quantum backreaction from inflationary fluctuations of a non-minimally coupled, massless scalar field. The scalar is assumed to be a spectator field in an inflationary model with a constant principal slow-roll. parameter. We regulate the infrared by matching onto a
After the Fall: Late-Time Spectroscopy of Type IIP Supernovae
Silverman, Jeffrey M; Wheeler, J Craig; Filippenko, Alexei V; Vinko, Jozsef; Marion, G H; Cenko, S Bradley; Chornock, Ryan; Clubb, Kelsey I; Foley, Ryan J; Graham, Melissa L; Kelly, Patrick L; Matheson, Thomas; Shields, Joseph C
2016-01-01
Herein we analyse late-time (post-plateau; 103 < t < 1229 d) optical spectra of low-redshift (z < 0.016), hydrogen-rich Type IIP supernovae (SNe IIP). Our newly constructed sample contains 91 nebular spectra of 38 SNe IIP, which is the largest dataset of its kind ever analysed in one study, and many of the objects have complementary photometric data. We determined the peak and total luminosity, velocity of the peak, HWHM intensity, and profile shape for many emission lines. Temporal evolution of these values and various flux ratios are studied. We also investigate the correlations between these measurements and photometric observables, such as the peak and plateau absolute magnitudes and the late-time light curve decline rates in various optical bands. The strongest and most robust result we find is that the luminosities of all spectral features (except those of helium) tend to be higher in objects with steeper late-time V-band decline rates. A steep late-time V-band slope likely arises from less eff...
SUPERLUMINOUS SUPERNOVAE POWERED BY MAGNETARS: LATE-TIME LIGHT CURVES AND HARD EMISSION LEAKAGE
Energy Technology Data Exchange (ETDEWEB)
Wang, S. Q.; Wang, L. J.; Dai, Z. G. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wu, X. F., E-mail: dzg@nju.edu.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)
2015-01-20
Recently, research performed by two groups has revealed that the magnetar spin-down energy injection model with full energy trapping can explain the early-time light curves of SN 2010gx, SN 2013dg, LSQ12dlf, SSS120810, and CSS121015 but fails to fit the late-time light curves of these superluminous supernovae (SLSNe). These results imply that the original magnetar-powered model is challenged in explaining these SLSNe. Our paper aims to simultaneously explain both the early- and late-time data/upper limits by considering the leakage of hard emissions. We incorporate quantitatively the leakage effect into the original magnetar-powered model and derive a new semianalytical equation. Comparing the light curves reproduced by our revised magnetar-powered model with the observed data and/or upper limits of these five SLSNe, we found that the late-time light curves reproduced by our semianalytical equation are in good agreement with the late-time observed data and/or upper limits of SN 2010gx, CSS121015, SN 2013dg, and LSQ12dlf and the late-time excess of SSS120810, indicating that the magnetar-powered model might be responsible for these SLSNe and that the gamma-ray and X-ray leakages are unavoidable when the hard photons were down-Comptonized to softer photons. To determine the details of the leakage effect and unveil the nature of SLSNe, more high-quality bolometric light curves and spectra of SLSNe are required.
Improved scatterometry time-to-solution using virtual reference
Vaid, Alok; Iddawela, Givantha; Tsai, Jamie; Wainreb, Gilad; Isbester, Paul; Kang, Byung Cheol (Charles); Klots, Michael; Katz, Yinon; Bozdog, Cornel; Sendelbach, Matt
2015-03-01
Advanced nodes require precise detection and control of intricate profile details - scatterometry is tool of choice for such requirements. Scatterometry is a model-based technique, and needs extensive reference metrology for qualification. Such reference measurements are costly, time-consuming and often destructive causing delays in deployment. With increasing number of scatterometry steps in flow, and the requirement to collect more reference data points to statistically qualify shrinking metrology specifications, the cost and time for reference metrology is exponentially increasing. This work is aimed to significantly reduce this need. We developed a novel methodology whereby scatterometry spectral information itself is used to predict "virtual" reference data. We qualify this methodology on several key applications from 20nm and 14nm node. We find that performance of solution developed using proposed methodology is indeed similar to performance of solution obtained using real reference data, thereby significantly reducing the lead time to develop scatterometry solutions.
Timing of fluoride intake and dental fluorosis on late-erupting permanent teeth.
Bhagavatula, Pradeep; Levy, Steven M; Broffitt, Barbara; Weber-Gasparoni, Karin; Warren, John J
2016-02-01
Very few studies have examined the relationship between timing of fluoride intake and development of dental fluorosis on late-erupting permanent teeth using period-specific fluoride intake information. This study examined this relationship using longitudinal fluoride intake information from the Iowa Fluoride Study. Participants' fluoride exposure and intake (birth to 10 years of age) from water, beverages, selected food products, dietary fluoride supplements, and fluoride toothpaste was collected using questionnaires sent to parents at 3- and 4- month intervals from birth to 48 months of age and every 6 months thereafter. Three trained and calibrated examiners used the Fluorosis Risk Index (FRI) categories to assess 16 late-erupting teeth among 465 study participants. A tooth was defined as having definitive fluorosis if any of the zones on that tooth had an FRI score of 2 or 3. Participants with questionable fluorosis were excluded from analyses. Descriptive and logistic regression analyses were performed to assess the importance of fluoride intake during different time periods. Most dental fluorosis in the study population was mild, with only four subjects (1%) having severe fluorosis (FRI Score 3). The overall prevalence of dental fluorosis was 27.8%. Logistic regression analyses showed that fluoride intake from each of the individual years from age 2 to 8 plays an important role in determining the risk of dental fluorosis for most late-erupting permanent teeth. The strongest association for fluorosis on the late-erupting permanent teeth was with fluoride intake during the sixth year of life. Late-erupting teeth may be susceptible to fluorosis for an extended period from about age 2 to 8. Although not as visually prominent as the maxillary central incisors, some of the late-erupting teeth are esthetically important and this should be taken into consideration when making recommendations about dosing of fluoride intake. © 2015 John Wiley & Sons A/S. Published by
Clues to the nature of SN 2009ip from photometric and spectroscopic evolution to late times
Energy Technology Data Exchange (ETDEWEB)
Graham, M. L. [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Sand, D. J. [Physics Department, Texas Tech University, Lubbock, TX 79409 (United States); Valenti, S.; Howell, D. A.; Parrent, J. [Las Cumbres Observatory Global Telescope Network, Goleta, CA 93117 (United States); Halford, M.; Zaritsky, D. [Astronomy Department, University of Arizona, Tucson, AZ 85721 (United States); Bianco, F. [Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Rest, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Dilday, B., E-mail: melissagraham@berkeley.edu [North Idaho College, 1000 W. Garden Avenue, Coeur d' Alene, ID 83814 (United States)
2014-06-01
We present time series photometric and spectroscopic data for the transient SN 2009ip from the start of its outburst in 2012 September until 2013 November. These data were collected primarily with the new robotic capabilities of the Las Cumbres Observatory Global Telescope Network, a specialized facility for time domain astrophysics, and includes supporting high-resolution spectroscopy from the Southern Astrophysical Research Telescope, Kitt Peak National Observatory, and Gemini Observatory. Based on our nightly photometric monitoring, we interpret the strength and timing of fluctuations in the light curve as interactions between fast-moving ejecta and an inhomogeneous circumstellar material (CSM) produced by past eruptions of this massive luminous blue variable (LBV) star. Our time series of spectroscopy in 2012 reveals that, as the continuum and narrow Hα flux from CSM interactions declines, the broad component of Hα persists with supernova (SN)-like velocities that are not typically seen in LBVs or SN impostor events. At late times, we find that SN 2009ip continues to decline slowly, at ≲ 0.01 mag day{sup –1}, with small fluctuations in slope similar to Type IIn supernovae (SNe IIn) or SN impostors but no further LBV-like activity. The late-time spectrum features broad calcium lines similar to both late-time SNe and SN impostors. In general, we find that the photometric and spectroscopic evolution of SN 2009ip is more similar to SNe IIn than either continued eruptions of an LBV star or SN impostors but we cannot rule out a nonterminal explosion. In this context, we discuss the implications for episodic mass loss during the late stages of massive star evolution.
Climate effects on late-season flight times of Massachusetts butterflies
Zipf, L.; Williams, E. H.; Primack, R. B.; Stichter, S.
2017-09-01
Although the responses of living organisms to climate change are being widely investigated, little attention has been given to such effects late in the growing season. We studied the late-season flight times of 20 species of butterflies in a geographically limited region, the state of Massachusetts in the USA, by examining change in dates of flight over a 22-year period and in response to average monthly temperature and precipitation. By analyzing the last 10% of each year's observations reported by observers of the Massachusetts Butterfly Club, we found that seven species remain in flight significantly later into the fall than they did two decades earlier, while two species show reduced late-season flight. Life history characteristics of the species, particularly voltinism and average fall flight dates, influenced whether warmer fall months led to increases or decreases in fall flight. Warmer Novembers often led to later fall flight, and wetter Augusts usually extended fall flight. These results document the effects of climate on late-season flight times of butterflies, add to an understanding of how warmer autumn conditions alter the phenology of different butterfly species, and show the usefulness of citizen science data.
Climate effects on late-season flight times of Massachusetts butterflies
Zipf, L.; Williams, E. H.; Primack, R. B.; Stichter, S.
2017-04-01
Although the responses of living organisms to climate change are being widely investigated, little attention has been given to such effects late in the growing season. We studied the late-season flight times of 20 species of butterflies in a geographically limited region, the state of Massachusetts in the USA, by examining change in dates of flight over a 22-year period and in response to average monthly temperature and precipitation. By analyzing the last 10% of each year's observations reported by observers of the Massachusetts Butterfly Club, we found that seven species remain in flight significantly later into the fall than they did two decades earlier, while two species show reduced late-season flight. Life history characteristics of the species, particularly voltinism and average fall flight dates, influenced whether warmer fall months led to increases or decreases in fall flight. Warmer Novembers often led to later fall flight, and wetter Augusts usually extended fall flight. These results document the effects of climate on late-season flight times of butterflies, add to an understanding of how warmer autumn conditions alter the phenology of different butterfly species, and show the usefulness of citizen science data.
Late Time Observations of the Afterglow and Environment of GRB 030329
Taylor, G B; Pihlström, Y M; Ghosh, T; Salter, C
2004-01-01
We present Very Long Baseline Interferometry (VLBI) observations 217 days after the gamma-ray burst of 2003 March 29. These observations provide further measurements of the size and position of GRB 030329 that are used to constrain the expansion rate and proper motion of this nearby GRB. The expansion rate appears to be slowing down with time, favoring expansion into a constant density interstellar medium, rather than a circumstellar wind with an r^-2 density profile. We also present late time Arecibo observations of the redshifted HI and OH absorption spectra towards GRB 030329. No absorption (or emission) is seen allowing us to place limits on the atomic neutral hydrogen of N_H < 8.5 x 10^20 cm^-2, and molecular hydrogen of N_H_2 < 1.4 x 10^22 cm^-2. Finally, we present VLA limits on the radio polarization from the afterglow of <2% at late times.
Unification of the inflation with late-time acceleration in Born-Infeld-$f(R)$ gravity
Makarenko, Andrey N
2014-01-01
We study accelerating dynamics from Born-Infeld-$f(R)$ gravity in a simplified conformal approach without matter. In our work (A.N. Makarenko, S. Odintsov, G.J. Olmo, Phys.Lett. B734 (2014) 36, [arXiv:1403.2850]) it was derived eventually any Dark Energy cosmology from above theory. In this Letter we apply the technique of (arXiv:1403.2850) to show that Born-Infeld-$f(R)$ gravity may describe very realistic universe admitting the unification of early-time inflation with late-time acceleration. Specifically, the evolution with periodic as well as non-periodic behavior is considered with possibility to cross the phantom-divide at early or late-times.
Directory of Open Access Journals (Sweden)
William C. Clyde
2013-07-01
Full Text Available Analysis of lithofacies, paleoflow directions, and sandstone petrography of upper Paleocene-lower Eocene paralic and continental sediments exposed along the transpressional suture zone of the western margin of the Indian plate indicate that the process of deformation and uplift of the carbonate shelf in this area had started by late Paleocene time. This tectonic uplift and deformation is documented by: (1 an overall shallowing upward synorogenic sequence of sediments, (2 proximal conglomerate facies (consisting of lower Paleocene and Mesozoic clasts dominating in the western part of the study area and distal facies of sandstone and shale dominating in the eastern part of the study area, (3 the existence of an unconformity of late Paleocene-early Eocene age in the Quetta and Kalat regions, (4 paleocurrent directions in deltaic and fluvial deposits indicating southeastward flowing sediment dispersal paths during late Paleocene-early Eocene time, which is opposite to that found in the late Cretaceous, suggesting a reversal in the depositional slope of the Cretaceous shelf, and (5 petrographic study of sandstones indicating a collision suture/fold thrust belt provenance. This episode of uplift and deformation could be the result of India-Arabian transpression with associated ophiolite obduction or, more likely, to represent the local response to initial India-Asia contact. The unroofing pattern and uplift geometry of the western Indian shelf suggests that this tectonism first started in the southern part of the study area (Kalat-Khuzdar area during the late Paleocene-early Eocene and proceeded northward in a time-transgressive fashion.
A Practical Solution for Time Synchronization in Wireless Sensor Networks
Directory of Open Access Journals (Sweden)
COCA, E.
2012-11-01
Full Text Available Time synchronization in wireless sensor node networks is a hot topic. Many papers present various software algorithms and hardware solutions to keep accurate time information on mobile nodes. In terms of real life applications wireless sensor nodes are preferred in many domains, starting with simple room monitoring and finishing with pipeline surveillance projects. Positioning applications are far more restrictive on timekeeping accuracy, as for the velocity of nodes calculations precise time or time difference values are needed. The accuracy of time information on nodes has to be always correlated with the application requirements. In this paper, we present some considerations regarding time synchronization linked with specific needs for individual practical applications. A practical low energy method of time keeping at node level is proposed and tested. The performances of the proposed solution in terms of short and long term stability and energy requirements are analyzed and compared with existing solutions. Simulation and experimental results, some advantages and disadvantages of the method are presented at the end of the paper.
Time dependent solution for acceleration of tau-leaping
Energy Technology Data Exchange (ETDEWEB)
Fu, Jin, E-mail: iamfujin@hotmail.com [Department of Computer Science, University of California, Santa Barbara (United States); Wu, Sheng, E-mail: sheng@cs.ucsb.edu [Department of Computer Science, University of California, Santa Barbara (United States); Petzold, Linda R., E-mail: petzold@cs.ucsb.edu [Department of Computer Science, University of California, Santa Barbara (United States)
2013-02-15
The tau-leaping method is often effective for speeding up discrete stochastic simulation of chemically reacting systems. However, when fast reactions are involved, the speed-up for this method can be quite limited. One way to address this is to apply a stochastic quasi-steady state assumption. However we must be careful when using this assumption. If the fast subsystem cannot reach a steady distribution fast enough, the quasi-steady-state assumption will propagate error into the simulation. To avoid these errors, we propose to use the time dependent solution rather than the quasi-steady-state. Generally speaking, the time dependent solution is not easy to derive for an arbitrary network. However, for some common motifs we do have time dependent solutions. We derive the time dependent solutions for these motifs, and then show how they can be used with tau-leaping to achieve substantial speed-ups, including for a realistic model of blood coagulation. Although the method is complicated, we have automated it.
Time dependent solution for acceleration of tau-leaping
Fu, Jin; Wu, Sheng; Petzold, Linda R.
2013-02-01
The tau-leaping method is often effective for speeding up discrete stochastic simulation of chemically reacting systems. However, when fast reactions are involved, the speed-up for this method can be quite limited. One way to address this is to apply a stochastic quasi-steady state assumption. However we must be careful when using this assumption. If the fast subsystem cannot reach a steady distribution fast enough, the quasi-steady-state assumption will propagate error into the simulation. To avoid these errors, we propose to use the time dependent solution rather than the quasi-steady-state. Generally speaking, the time dependent solution is not easy to derive for an arbitrary network. However, for some common motifs we do have time dependent solutions. We derive the time dependent solutions for these motifs, and then show how they can be used with tau-leaping to achieve substantial speed-ups, including for a realistic model of blood coagulation. Although the method is complicated, we have automated it.
Analysis of Late--time Light Curves of Type IIb, Ib and Ic Supernovae
Wheeler, J Craig; Clocchiatti, A
2014-01-01
The shape of the light curve peak of radioactive-powered core-collapse "stripped-envelope," supernovae constrains the ejecta mass, nickel mass, and kinetic energy by the brightness and diffusion time for a given opacity and observed expansion velocity. Late-time light curves give constraints on the same parameters, given the gamma-ray opacity. Previous work has shown that the principal light curve peaks for SN IIb with small amounts of hydrogen and for hydrogen/helium-deficient SN Ib/c are often rather similar near maximum light, suggesting similar ejecta masses and kinetic energies, but that late-time light curves show a wide dispersion, suggesting a dispersion in ejecta masses and kinetic energies. It was also shown that SN IIb and SN Ib/c can have very similar late-time light curves, but different ejecta velocities demanding significantly different ejecta masses and kinetic energies. We revisit these topics by collecting and analyzing well-sampled single color and quasi-bolometric light curves from the lit...
Why are they late? Timing abilities and executive control among students with learning disabilities.
Grinblat, Nufar; Rosenblum, Sara
2016-12-01
While a deficient ability to perform daily tasks on time has been reported among students with learning disabilities (LD), the underlying mechanism behind their 'being late' is still unclear. This study aimed to evaluate the organization in time, time estimation abilities, actual performance time pertaining to specific daily activities, as well as the executive functions of students with LD in comparison to those of controls, and to assess the relationships between these domains among each group. The participants were 27 students with LD, aged 20-30, and 32 gender and age-matched controls who completed the Time Organization and Participation Scale (TOPS) and the Behavioral Rating Inventory of Executive Function-Adult version (BRIEF-A). In addition, their ability to estimate the time needed to complete the task of preparing a cup of coffee as well as their actual performance time were evaluated. The results indicated that in comparison to controls, students with LD showed significantly inferior organization in time (TOPS) and executive function abilities (BRIEF-A). Furthermore, their time estimation abilities were significantly inferior and they required significantly more time to prepare a cup of coffee. Regression analysis identified the variables that predicted organization in time and task performance time among each group. The significance of the results for both theoretical and clinical implications are discussed. What this paper adds? This study examines the underlying mechanism of the phenomena of being late among students with LD. Following a recent call for using ecologically valid assessments, the functional daily ability of students with LD to prepare a cup of coffee and to organize time were investigated. Furthermore, their time estimation and executive control abilities were examined as a possible underlying mechanism for their lateness. Although previous studies have indicated executive control deficits among students with LD, to our knowledge, this
The influence of climate on species distribution over time and space during the late Quaternary
Carotenuto, F.; Di Febbraro, M.; Melchionna, M.; Castiglione, S.; Saggese, F.; Serio, C.; Mondanaro, A.; Passaro, F.; Loy, A.; Raia, P.
2016-10-01
Understanding the effect of climate on the composition of communities and its change over time and space is one of the major aims in ecology and paleoecology. Herein, we tackled on this issue by studying late Quaternary large mammal paleocommunities of Eurasia. The late Quaternary was a period of strong environmental instability, especially characterized by the occurrence of the last glacial maximum (LGM). We used community phylogenetics and joint species distribution models in order to understand the factors determining paleocommunity composition in the late Quaternary. Our results support the existence of strong climatic selection operating on the LGM fauna, both through the disappearance of warm-adapted species such as Elephas antiquus, Hippopothamus amphibious, and Stephanorhinus hemitoechus, and by setting the stage for the existence of a community characterized by cold-adapted large mammals. Patterns of abundance in the fossil record, co-occurrence between species pairs, and the extent of climatic forcing on faunal composition, differ between paleocommunities, but not between extinct and extant species, which is consistent with the idea that climate change, rather than the presence of humans, exerted a major effect on the survival of the late Quaternary megafauna.
Gauss-Bonnet Cosmology Unifying Late and Early-time Acceleration Eras with Intermediate Eras
Oikonomou, V K
2016-01-01
In this paper we demonstrate that with vacuum $F(G)$ gravity it is possible to describe the unification of late and early-time acceleration eras with the radiation and matter domination era. The Hubble rate of the unified evolution contains two mild singularities, so called Type IV singularities, and the evolution itself has some appealing features, such as the existence of a deceleration-acceleration transition at late times. We also address quantitatively a fundamental question related to modified gravity models description of cosmological evolution: Is it possible for all modified gravity descriptions of our Universe evolution, to produce a nearly scale invariant spectrum of primordial curvature perturbations? As we demonstrate, the answer for the $F(G)$ description is no, since the resulting power spectrum is not scale invariant, in contrast to the $F(R)$ description studied in the literature. Therefore, although the cosmological evolution can be realized in the context of vacuum $F(G)$ gravity, the evolu...
Time series hyperspectral chemical imaging data: challenges, solutions and applications.
Gowen, A A; Marini, F; Esquerre, C; O'Donnell, C; Downey, G; Burger, J
2011-10-31
Hyperspectral chemical imaging (HCI) integrates imaging and spectroscopy resulting in three-dimensional data structures, hypercubes, with two spatial and one wavelength dimension. Each spatial image pixel in a hypercube contains a spectrum with >100 datapoints. While HCI facilitates enhanced monitoring of multi-component systems; time series HCI offers the possibility of a more comprehensive understanding of the dynamics of such systems and processes. This implies a need for modeling strategies that can cope with the large multivariate data structures generated in time series HCI experiments. The challenges posed by such data include dimensionality reduction, temporal morphological variation of samples and instrumental drift. This article presents potential solutions to these challenges, including multiway analysis, object tracking, multivariate curve resolution and non-linear regression. Several real world examples of time series HCI data are presented to illustrate the proposed solutions. Copyright © 2011 Elsevier B.V. All rights reserved.
Time and "angular" dependent backgrounds from stationary axisymmetric solutions
Obregón, O; Ryan, M P; Obregon, Octavio; Quevedo, Hernando; Ryan, Michael P.
2004-01-01
Backgrounds depending on time and on "angular" variable, namely polarized and unpolarized $S^1 \\times S^2$ Gowdy models, are generated as the sector inside the horizons of the manifold corresponding to axisymmetric solutions. As is known, an analytical continuation of ordinary $D$-branes, $iD$-branes allows one to find $S$-brane solutions. Simple models have been constructed by means of analytic continuation of the Schwarzchild and the Kerr metrics. The possibility of studying the $i$-Gowdy models obtained here is outlined with an eye toward seeing if they could represent some kind of generalized $S$-branes depending not only on time but also on an ``angular'' variable.
Late-time tails in a stationary axisymmetric EMDA black hole geometry
Institute of Scientific and Technical Information of China (English)
Pan Qi-Yuan; Jing Ji-Liang
2005-01-01
The late-time tails of massless and self-interacting (SI) (massive) scalar fields are investigated analytically in a stationary axisymmetric Einstein-Maxwell dilaton-axion (EMDA) black hole geometry. It is shown that the asymptotic behaviour of massless perturbations is dominated by an inverse power-law decaying tail and the intermediate asymptotic behaviour of SI (massive) perturbations is dominated by an oscillatory one.
Viability of Arctan Model of f(R) Gravity for Late-time Cosmology
Dutta, Koushik; Patel, Avani
2016-01-01
$f(R)$ modifications of Einstein's gravity is an interesting possibility to explain the late time acceleration of the Universe. In this work we explore the cosmological viability of one such $f(R)$ modification proposed in (Kruglov:2013). We show that the model violates fifth-force constraints. The model is also plagued with the issue of curvature singularity in a spherically collapsing object, where the effective scalar field reaches to the point of diverging scalar curvature.
Orbital control on the timing of oceanic anoxia in the Late Cretaceous
Batenburg, Sietske J.; De Vleeschouwer, David; Sprovieri, Mario; Hilgen, Frederik J.; Gale, Andrew S.; Singer, Brad S.; Koeberl, Christian; Coccioni, Rodolfo; Claeys, Philippe; Montanari, Alessandro
2016-10-01
The oceans at the time of the Cenomanian-Turonian transition were abruptly perturbed by a period of bottom-water anoxia. This led to the brief but widespread deposition of black organic-rich shales, such as the Livello Bonarelli in the Umbria-Marche Basin (Italy). Despite intensive studies, the origin and exact timing of this event are still debated. In this study, we assess leading hypotheses about the inception of oceanic anoxia in the Late Cretaceous greenhouse world by providing a 6 Myr long astronomically tuned timescale across the Cenomanian-Turonian boundary. We procure insights into the relationship between orbital forcing and the Late Cretaceous carbon cycle by deciphering the imprint of astronomical cycles on lithologic, physical properties, and stable isotope records, obtained from the Bottaccione, Contessa and Furlo sections in the Umbria-Marche Basin. The deposition of black shales and cherts, as well as the onset of oceanic anoxia, is related to maxima in the 405 kyr cycle of eccentricity-modulated precession. Correlation to radioisotopic ages from the Western Interior (USA) provides unprecedented age control for the studied Italian successions. The most likely tuned age for the base of the Livello Bonarelli is 94.17 ± 0.15 Ma (tuning 1); however, a 405 kyr older age cannot be excluded (tuning 2) due to uncertainties in stratigraphic correlation, radioisotopic dating, and orbital configuration. Our cyclostratigraphic framework suggests that the exact timing of major carbon cycle perturbations during the Cretaceous may be linked to increased variability in seasonality (i.e. a 405 kyr eccentricity maximum) after the prolonged avoidance of seasonal extremes (i.e. a 2.4 Myr eccentricity minimum). Volcanism is probably the ultimate driver of oceanic anoxia, but orbital periodicities determine the exact timing of carbon cycle perturbations in the Late Cretaceous. This unites two leading hypotheses about the inception of oceanic anoxia in the Late
Associations between time spent in green areas and physical activity among late middle-aged adults
Directory of Open Access Journals (Sweden)
Bart Dewulf
2016-11-01
Full Text Available Physical activity is an important facilitator for health and wellbeing, especially for late middle-aged adults, who are more susceptible to cardiovascular diseases. Physical activity performed in green areas is supposed to be particularly beneficial, so we studied whether late middle- aged adults are more active in green areas than in non-green areas and how this is influenced by individual characteristics and the level of neighbourhood greenness. We tracked 180 late middle-aged (58 to 65 years adults using global positioning system and accelerometer data to know whether and where they were sedentary or active. These data were combined with information on land use to obtain information on the greenness of sedentary and active hotspots. We found that late middle-aged adults are more physically active when spending more time in green areas than in non-green areas. Spending more time at home and in non-green areas was found to be associated with more sedentary behaviour. Time spent in non-green areas was found to be related to more moderate-to-vigorous physical activity (MVPA for males and to less MVPA for females. The positive association between time spent in green areas and MVPA was the strongest for highly educated people and for those living in a green neighbourhood. This study shows that the combined use of global positioning system and accelerometer data facilitates understanding of where people are sedentary or physically active, which can help policy makers encourage activity in this age cohort.
Implicit versus explicit momentum relaxation time solution for semiconductor nanowires
Energy Technology Data Exchange (ETDEWEB)
Marin, E. G., E-mail: egmarin@ugr.es; Ruiz, F. G., E-mail: franruiz@ugr.es; Godoy, A., E-mail: agodoy@ugr.es; Tienda-Luna, I. M.; Gámiz, F. [Departamento de Electrónica, Universidad de Granada, Av. Fuentenueva S/N, 18071–Granada (Spain)
2015-07-14
We discuss the necessity of the exact implicit Momentum Relaxation Time (MRT) solution of the Boltzmann transport equation in order to achieve reliable carrier mobility results in semiconductor nanowires. Firstly, the implicit solution for a 1D electron gas with a isotropic bandstructure is presented resulting in the formulation of a simple matrix system. Using this solution as a reference, the explicit approach is demonstrated to be inaccurate for the calculation of inelastic anisotropic mechanisms such as polar optical phonons, characteristic of III-V materials. Its validity for elastic and isotropic mechanisms is also evaluated. Finally, the implications of the MRT explicit approach inaccuracies on the total mobility of Si and III-V NWs are studied.
Early-time solution of the horizontal unconfined aquifer in the build-up phase
Gravanis, Elias; Akylas, Evangelos
2017-04-01
The Boussinesq equation is a dynamical equation for the free surface of saturated subsurface flows over an impervious bed. Boussinesq equation is non-linear. The non-linearity comes from the reduction of the dimensionality of the problem: The flow is assumed to be vertically homogeneous, therefore the flow rate through a cross section of the flow is proportional to the free surface height times the hydraulic gradient, which is assumed to be equal to the slope of the free surface (Dupuit approximation). In general, 'vertically' means normally on the bed; combining the Dupuit approximation with the continuity equation leads to the Boussinesq equation. There are very few transient exact solutions. Self- similar solutions have been constructed in the past by various authors. A power series type of solution was derived for a self-similar Boussinesq equation by Barenblatt in 1990. That type of solution has generated a certain amount of literature. For the unconfined flow case for zero recharge rate Boussinesq derived for the horizontal aquifer an exact solution assuming separation of variables. This is actually an exact asymptotic solution of the horizontal aquifer recession phase for late times. The kinematic wave is an interesting solution obtained by dropping the non-linear term in the Boussinesq equation. Although it is an approximate solution, and holds well only for small values of the Henderson and Wooding λ parameter (that is, for steep slopes, high conductivity or small recharge rate), it becomes less and less approximate for smaller values of the parameter, that is, it is asymptotically exact with respect to that parameter. In the present work we consider the case of the unconfined subsurface flow over horizontal bed in the build-up phase under constant recharge rate. This is a case with an infinite Henderson and Wooding parameter, that is, it is the limiting case where the non-linear term is present in the Boussinesq while the linear spatial derivative term
Late-time evolution of cosmological models with fluids obeying a Shan-Chen-like equation of state
Bini, Donato; Geralico, Andrea
2016-01-01
Classical as well as quantum features of the late-time evolution of cosmological models with fluids obeying a Shan-Chen-like equation of state are studied. The latter is of the type $p=w_{\\rm eff}(\\rho)\\,\\rho$, and has been used in previous works to describe, e.g., a possible scenario for the growth of the dark-energy content of the present Universe. At the classical level the fluid dynamics in a spatially flat Friedmann-Robertson-Walker background implies the existence of two possible equilibrium solutions depending on the model parameters, associated with (asymptotic) finite pressure and energy density. We show that no future cosmological singularity is developed during the evolution for this specific model. The corresponding quantum effects in the late-time behavior of the system are also investigated within the framework of quantum geometrodynamics, i.e., by solving the (minisuperspace) Wheeler-DeWitt equation in the Born-Oppenheimer approximation, constructing wave-packets and analyzing their behavior.
Progressive Red Shifts in the Late-Time Spectra of Type Ia Supernovae
Black, C S; Parrent, J T
2016-01-01
We examine the evolution of late-time, optical nebular features of Type Ia supernovae (SNe Ia) using a sample consisting of 160 spectra of 27 normal SNe Ia taken from the literature as well as unpublished spectra of SN 2008Q and ASASSN-14lp. Particular attention was given to nebular features between 4000$-$6000 \\AA\\ in terms of temporal changes in width and central wavelength. Analysis of the prominent late-time 4700 \\AA\\ feature shows a progressive central wavelength shift from $\\sim$4600 \\AA\\ to longer wavelengths out to at least day +300 for our entire sample. We find no evidence for the feature's red-ward shift slowing or halting at an [Fe III] blend centroid of 4701 \\AA\\ as has been proposed. The width of the feature also steadily increases with a FWHM $\\sim$170 \\AA\\ at day +100 growing to 200 \\AA\\ or more by day +350. Two weaker adjacent features around 4850 and 5000 \\AA\\ exhibit very similar red shifts to that of the 4700 \\AA\\ feature but show no change in width until very late times. We discuss possib...
Why are you late? Investigating the role of time management in time-based prospective memory.
Waldum, Emily R; McDaniel, Mark A
2016-08-01
Time-based prospective memory tasks (TBPM) are those that are to be performed at a specific future time. Contrary to typical laboratory TBPM tasks (e.g., hit the Z key every 5 min), many real-world TBPM tasks require more complex time-management processes. For instance, to attend an appointment on time, one must estimate the duration of the drive to the appointment and then use this estimate to create and execute a secondary TBPM intention (e.g., "I need to start driving by 1:30 to make my 2:00 appointment on time"). Future under- and overestimates of drive time can lead to inefficient TBPM performance with the former lending to missed appointments and the latter to long stints in the waiting room. Despite the common occurrence of complex TBPM tasks in everyday life, to date, no studies have investigated how components of time management, including time estimation, affect behavior in such complex TBPM tasks. Therefore, the current study aimed to investigate timing biases in both older and younger adults and, further, to determine how such biases along with additional time management components including planning and plan fidelity influence complex TBPM performance. Results suggest for the first time that younger and older adults do not always utilize similar timing strategies, and as a result, can produce differential timing biases under the exact same environmental conditions. These timing biases, in turn, play a vital role in how efficiently both younger and older adults perform a later TBPM task that requires them to utilize their earlier time estimate. (PsycINFO Database Record
Analytic solutions of tunneling time through smooth barriers
Xiao, Zhi; Huang, Hai
2016-03-01
In the discussion of temporary behaviors of quantum tunneling, people usually like to focus their attention on rectangular barrier with steep edges, or to deal with smooth barrier with semi-classical or even numerical calculations. Very few discussions on analytic solutions of tunneling through smooth barrier appear in the literature. In this paper, we provide two such examples, a semi-infinite long barrier V ( x ) = /A 2 [ 1 + tanh ( x / a ) ] and a finite barrier V(x) = A sech2(x/a). To each barrier, we calculate the associated phase time and dwell time after obtaining the analytic solution. The results show that, different from rectangular barrier, phase time or dwell time does increase with the length parameter a controlling the effective extension of the barrier. More interestingly, for the finite barrier, phase time or dwell time exhibits a peak in k-space. A detailed analysis shows that this interesting behavior can be attributed to the strange tunneling probability Ts(k), i.e., Ts(k) displays a unit step function-like profile Θ(k - k0), especially when a is large, say, a ≫ 1/κ, 1/k. And k 0 ≡ √{ m A } / ħ is exactly where the peak appears in phase or dwell time k-spectrum. Thus only those particles with k in a very narrow interval around k0 are capable to dwell in the central region of the barrier sufficiently long.
Shabani, Hamid; Ziaie, Amir Hadi
2017-08-01
In this work, we study the late-time cosmological solutions of f(R,T)=g(R)+h(-T) models assuming that the conservation of the energy-momentum tensor ( EMT) is violated. We perform our analysis through constructing an autonomous dynamical system for the equations of motion. We study the stability properties of solutions via considering linear perturbations about the related equilibrium points. Moreover, we parameterize the Lagrangian by introducing the parameters m( r) and n( s). These parameters which are constructed out of the functions g(R) and h(-T) play the main role in finding the late-time behavior of the solutions. We find that there exist, in general, three classes of solutions; all models with n>0 include a proper transition from a prolonged matter era to a de Sitter solution. Models with -0.51, for at least a root of equation n(s)=s-1, include an unphysical dark energy solution preceding an improper matter era. Finally, for nlaw dependency i.e., f(R,T)=R^{β }+(-T)^{α } can be observationally motivating for m→ 0+ and -0.024<α <0.02 and therefore could provide a suitable setting for later investigations.
Explicit solution of Calderon preconditioned time domain integral equations
Ulku, Huseyin Arda
2013-07-01
An explicit marching on-in-time (MOT) scheme for solving Calderon-preconditioned time domain integral equations is proposed. The scheme uses Rao-Wilton-Glisson and Buffa-Christiansen functions to discretize the domain and range of the integral operators and a PE(CE)m type linear multistep to march on in time. Unlike its implicit counterpart, the proposed explicit solver requires the solution of an MOT system with a Gram matrix that is sparse and well-conditioned independent of the time step size. Numerical results demonstrate that the explicit solver maintains its accuracy and stability even when the time step size is chosen as large as that typically used by an implicit solver. © 2013 IEEE.
Modeling the Quiet Time Outflow Solution in the Polar Cap
Glocer, Alex
2011-01-01
We use the Polar Wind Outflow Model (PWOM) to study the geomagnetically quiet conditions in the polar cap during solar maximum, The PWOM solves the gyrotropic transport equations for O(+), H(+), and He(+) along several magnetic field lines in the polar region in order to reconstruct the full 3D solution. We directly compare our simulation results to the data based empirical model of Kitamura et al. [2011] of electron density, which is based on 63 months of Akebono satellite observations. The modeled ion and electron temperatures are also compared with a statistical compilation of quiet time data obtained by the EISCAT Svalbard Radar (ESR) and Intercosmos Satellites (Kitamura et al. [2011]). The data and model agree reasonably well. This study shows that photoelectrons play an important role in explaining the differences between sunlit and dark results, ion composition, as well as ion and electron temperatures of the quiet time polar wind solution. Moreover, these results provide validation of the PWOM's ability to model the quiet time ((background" solution.
Clues To The Nature of SN 2009ip from Photometric and Spectroscopic Evolution to Late Times
Graham, M L; Valenti, S; Howell, D A; Parrent, J; Halford, M; Zaritsky, D; Bianco, F; Rest, A; Dilday, B
2014-01-01
We present time series photometric and spectroscopic data for the transient SN 2009ip from the start of its outburst in September 2012 until November 2013. This data was collected primarily with the new robotic capabilities of the Las Cumbres Observatory Global Telescope Network, a specialized facility for time domain astrophysics, and includes supporting high-resolution spectroscopy from the Southern Astrophysical Research Telescope, Kitt Peak National Observatory, and Gemini Observatory. Based on our nightly photometric monitoring, we interpret the strength and timing of fluctuations in the light curve as interactions between fast-moving ejecta and an inhomogeneous CSM produced by past eruptions of this massive luminous blue variable (LBV) star. Our time series of spectroscopy in 2012 reveals that, as the continuum and narrow H-alpha flux from CSM interactions declines, the broad component of H-alpha persists with SN-like velocities that are not typically seen in LBVs or SN Impostor events. At late times we...
Unifying inflation with late-time acceleration by a BIonic system
Energy Technology Data Exchange (ETDEWEB)
Sepehri, Alireza, E-mail: alireza.sepehri@uk.ac.ir [Faculty of Physics, Shahid Bahonar University, P.O. Box 76175, Kerman (Iran, Islamic Republic of); Rahaman, Farook, E-mail: rahaman@iucaa.ernet.in [Department of Mathematics, Jadavpur University, Kolkata 700032, West Bengal (India); Setare, Mohammad Reza, E-mail: rezakord@ipm.ir [Department of Science, Campus of Bijar, University of Kurdistan, Bijar (Iran, Islamic Republic of); Pradhan, Anirudh, E-mail: pradhan@iucaa.ernet.in [Department of Mathematics, Institute of Applied Sciences & Humanities, GLA University, Mathura-281 406, U.P. (India); Capozziello, Salvatore, E-mail: capozziello@na.infn.it [Dipartimento di Fisica, Universitá di Napoli “Federico II”, I-80126 Napoli (Italy); INFN Sezione di Napoli, Complesso Universitario di Monte S. Angelo, Edificio G, I-80126 Napoli (Italy); Gran Sasso Science Institute (INFN), Viale F. Crispi, 7, I-67100 L' Aquila (Italy); Sardar, Iftikar Hossain, E-mail: iftikar.spm@gmail.com [Department of Mathematics, Jadavpur University, Kolkata 700032, West Bengal (India)
2015-07-30
We propose a cosmological model that unifies inflation, deceleration and acceleration phases of expansion history by a BIonic system. At the beginning, there are k black fundamental strings that transited to the BIon configuration at a given corresponding point. Here, two coupled universes, brane and antibrane, are created interacting each other through a wormhole and inflate. With decreasing temperature, the energy of this wormhole flows into the universe branes and leads to inflation. After a short time, the wormhole evaporates, the inflation ends and a deceleration epoch starts. By approaching the brane and antibrane universes together, a tachyon is born, grows and causes the creation of a new wormhole. At this time, the brane and antibrane universes result connected again and the late-time acceleration era of the universe begins. We compare our model with previous unified phantom models and observational data obtaining some cosmological parameters like temperature in terms of time. We also find that deceleration parameter is negative during inflation and late-time acceleration epochs, while it is positive during the deceleration era. This means that the model is consistent, in principle, with cosmological observations.
Unifying inflation with late-time acceleration by a BIonic system
Directory of Open Access Journals (Sweden)
Alireza Sepehri
2015-07-01
Full Text Available We propose a cosmological model that unifies inflation, deceleration and acceleration phases of expansion history by a BIonic system. At the beginning, there are k black fundamental strings that transited to the BIon configuration at a given corresponding point. Here, two coupled universes, brane and antibrane, are created interacting each other through a wormhole and inflate. With decreasing temperature, the energy of this wormhole flows into the universe branes and leads to inflation. After a short time, the wormhole evaporates, the inflation ends and a deceleration epoch starts. By approaching the brane and antibrane universes together, a tachyon is born, grows and causes the creation of a new wormhole. At this time, the brane and antibrane universes result connected again and the late-time acceleration era of the universe begins. We compare our model with previous unified phantom models and observational data obtaining some cosmological parameters like temperature in terms of time. We also find that deceleration parameter is negative during inflation and late-time acceleration epochs, while it is positive during the deceleration era. This means that the model is consistent, in principle, with cosmological observations.
Unifying inflation with late-time acceleration by a BIonic system
Sepehri, Alireza; Rahaman, Farook; Setare, Mohammad Reza; Pradhan, Anirudh; Capozziello, Salvatore; Sardar, Iftikar Hossain
2015-07-01
We propose a cosmological model that unifies inflation, deceleration and acceleration phases of expansion history by a BIonic system. At the beginning, there are k black fundamental strings that transited to the BIon configuration at a given corresponding point. Here, two coupled universes, brane and antibrane, are created interacting each other through a wormhole and inflate. With decreasing temperature, the energy of this wormhole flows into the universe branes and leads to inflation. After a short time, the wormhole evaporates, the inflation ends and a deceleration epoch starts. By approaching the brane and antibrane universes together, a tachyon is born, grows and causes the creation of a new wormhole. At this time, the brane and antibrane universes result connected again and the late-time acceleration era of the universe begins. We compare our model with previous unified phantom models and observational data obtaining some cosmological parameters like temperature in terms of time. We also find that deceleration parameter is negative during inflation and late-time acceleration epochs, while it is positive during the deceleration era. This means that the model is consistent, in principle, with cosmological observations.
Translation invariant time-dependent solutions to massive gravity II
Energy Technology Data Exchange (ETDEWEB)
Mourad, J.; Steer, D.A., E-mail: mourad@apc.univ-paris7.fr, E-mail: steer@apc.univ-paris7.fr [AstroParticule and Cosmologie, UMR 7164-CNRS, Université Denis Diderot-Paris 7, CEA, Observatoire de Paris, F-75205 Paris Cedex 13 (France)
2014-06-01
This paper is a sequel to JCAP 12 (2013) 004 and is also devoted to translation-invariant solutions of ghost-free massive gravity in its moving frame formulation. Here we consider a mass term which is linear in the vielbein (corresponding to a β{sub 3} term in the 4D metric formulation) in addition to the cosmological constant. We determine explicitly the constraints, and from the initial value formulation show that the time-dependent solutions can have singularities at a finite time. Although the constraints give, as in the β{sub 1} case, the correct number of degrees of freedom for a massive spin two field, we show that the lapse function can change sign at a finite time causing a singular time evolution. This is very different to the β{sub 1} case where time evolution is always well defined. We conclude that the β{sub 3} mass term can be pathological and should be treated with care.
Translation invariant time-dependent solutions to massive gravity II
Mourad, J
2014-01-01
This paper is a sequel to arXiv:1310.6560 [hep-th] and is also devoted to translation-invariant solutions of ghost-free massive gravity in its moving frame formulation. Here we consider a mass term which is linear in the vielbein (corresponding to a $\\beta_3$ term in the 4D metric formulation) in addition to the cosmological constant. We determine explicitly the constraints, and from the initial value formulation show that the time-dependent solutions can have singularities at a finite time. Although the constraints give, as in the $\\beta_1$ case, the correct number of degrees of freedom for a massive spin two field, we show that the lapse function can change sign at a finite time causing a singular time evolution. This is very different to the $\\beta_1$ case where time evolution is always well defined. We conclude that the $\\beta_3$ mass term can be pathological and should be treated with care.
Directory of Open Access Journals (Sweden)
Syed Asif Ali Shah
2012-01-01
Full Text Available Flow time analysis is a powerful concept to analyze the flow time of any arriving customer in any system at any instant. A load management mechanism can be employed very effectively in any queueing system by utilizing a system which provides probability of dual service rate. In this paper, we develop and demonstrate the flow and service processes transition diagram to determine the flow time of a customer in a load management late arrival state dependent finite discrete time queueing system with dual service rate where customers are hypogeometrically distributed. We compute the probability mass function of each starting state and total probability mass function. The obtained analytical results are validated with simulation results for varying values of arrival and service probabilities.
Timing, duration, and causes for Late Jurassic-Early Cretaceous anoxia in the Barents Sea
Georgiev, Svetoslav V.; Stein, Holly J.; Hannah, Judith L.; Xu, Guangping; Bingen, Bernard; Weiss, Hermann M.
2017-03-01
Re-Os isochron ages for black shales of the Hekkingen Formation in the Barents Sea constrain the onset (157.7 ± 1.3 Ma) and termination (138.8 ± 1.0 Ma), and thereby indicate a long duration (∼19 Myr) of widespread Jurassic-Cretaceous anoxia in the Arctic. Integration of these new Re-Os ages with published radiometric ages, ammonite biostratigraphy and geomagnetic polarity chrons shows shorter late Oxfordian-late Kimmeridgian and longer Berriasian stages relative to estimates in the 2012 and 2016 Geological Time Scales. Late Jurassic anoxia was likely the result of warming climate due to high atmospheric CO2 levels from increased oceanic crust production. Rising temperatures enhanced weathering and nutrient supply, increased productivity, and slowed ocean circulation before a sea-level rise brought anoxic waters onto continental shelves. Assessment of new and published Os- and Sr-isotopic data suggests that prolonged oceanic anoxia required a sustained CO2 source from fast spreading rates and/or longer subduction zones and spreading ridges to balance large burial of carbon in voluminous Upper Jurassic and Lower Cretaceous black shales.
Timing of indicated late-preterm and early-term birth.
Spong, Catherine Y; Mercer, Brian M; D'alton, Mary; Kilpatrick, Sarah; Blackwell, Sean; Saade, George
2011-08-01
The growing public health awareness of prematurity and its complications has prompted careful evaluation of the timing of deliveries by clinicians and hospitals. Preterm birth is associated with significant morbidity and mortality, and affects more than half a million births in the United States each year. In some situations, however, a late-preterm or early-term birth is the optimal outcome for the mother, child, or both owing to conditions that can result in worse outcomes if pregnancy is allowed to continue. These conditions may be categorized as placental, maternal, or fetal, including conditions such as placenta previa, preeclampsia, and multiple gestations. Some risks associated with early delivery are common to all conditions, including prematurity-related morbidities (eg, respiratory distress syndrome and intraventricular hemorrhage) as well as maternal intrapartum morbidities such as failed induction and cesarean delivery. However, when continuation of the pregnancy is associated with more risks such as hemorrhage, uterine rupture, and stillbirth, preterm delivery maybe indicated. In February 2011, the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the Society for Maternal-Fetal Medicine held a workshop titled "Timing of Indicated Late Preterm and Early Term Births." The goal of the workshop was to synthesize the available information regarding conditions that may result in medically indicated late-preterm and early-term births to determine the potential risks and benefits of delivery compared with continued pregnancy, determine the optimal gestational age for delivery of affected pregnancies when possible, and inform future research regarding these issues. Based on available data and expert opinion, optimal timing for delivery for specific conditions was determined by consensus.
Late time cosmological phase transitions 1: Particle physics models and cosmic evolution
Frieman, Joshua A.; Hill, Christopher T.; Watkins, Richard
1991-01-01
We described a natural particle physics basis for late-time phase transitions in the universe. Such a transition can seed the formation of large-scale structure while leaving a minimal imprint upon the microwave background anisotropy. The key ingredient is an ultra-light pseudo-Nambu-Goldstone boson with an astronomically large (O(kpc-Mpc)) Compton wavelength. We analyze the cosmological signatures of and constraints upon a wide class of scenarios which do not involve domain walls. In addition to seeding structure, coherent ultra-light bosons may also provide unclustered dark matter in a spatially flat universe, omega sub phi approx. = 1.
Charges and currents in quantum spin chains: late-time dynamics and spontaneous currents
Fagotti, Maurizio
2017-01-01
We review the structure of the conservation laws in noninteracting spin chains and unveil a formal expression for the corresponding currents. We briefly discuss how interactions affect the picture. In the second part, we explore the effects of a localized defect. We show that the emergence of spontaneous currents near the defect undermines any description of the late-time dynamics by means of a stationary state in a finite chain. In particular, the diagonal ensemble does not work. Finally, we provide numerical evidence that simple generic localized defects are not sufficient to induce thermalization.
Directory of Open Access Journals (Sweden)
L. Toledo Sesma
2016-01-01
Full Text Available We construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. This approach is applied to anisotropic cosmological Bianchi type I model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Under this approach, we present an isotropization mechanism for the Bianchi I cosmological model through the analysis of the ratio between the anisotropic parameters and the volume of the Universe which in general keeps constant or runs into zero for late times. We also find that the presence of extra dimensions in this model can accelerate the isotropization process depending on the momenta moduli values. Finally, we present some solutions to the corresponding Wheeler-DeWitt (WDW equation in the context of standard quantum cosmology.
BEM Solution in the Time Domain for a Moving Time-Dependent Force
DEFF Research Database (Denmark)
Rasmussen, K. M.; Nielsen, Søren R. K.; Kirkegaard, Poul Henning
The problem of a moving time dependent concentrated force on the surface of an elastic halfspace is of interest in the analysis of traffic generated noise. The BEM is superior to the FEM in solving such problems due to its inherent ability so satisfy the radiation conditions exactly. In this paper...... a model based on the BEM is formulated for the solution of the mentioned problem. A numerical solution is obtained for the 2D plane strain case, and comparison is made with the results obtained from a corresponding FEM solution with an impedance absorbing boundary condition....
Extracting the late-time kinetic Sunyaev-Zel'dovich effect
Munshi, D; Dixon, K L; Coles, P
2015-01-01
We propose a novel technique to separate the late-time, post-reionization component of the kinetic Sunyaev-Zeldovich (kSZ) effect from the contribution to it from a (poorly understood and probably patchy) reionization history. The kSZ effect is one of the most promising probe of the {\\em missing baryons} in the Universe. We study the possibility of reconstructing it in three dimensions (3D), using future spectroscopic surveys such as the Euclid survey. By reconstructing a 3D template from galaxy density and peculiar velocity fields from spectroscopic surveys we cross-correlate the estimator against CMB maps. The resulting cross-correlation can help us to map out the kSZ contribution to CMB in 3D as a function of redshift thereby extending previous results which use tomographic reconstruction. This allows the separation of the late time effect from the contribution owing to reionization. By construction, it avoids contamination from foregrounds, primary CMB, tSZ effect as well as from star forming galaxies. Du...
Late time cooling of neutron star transients and the physics of the inner crust
Deibel, Alex; Brown, Edward F; Reddy, Sanjay
2016-01-01
An accretion outburst onto a neutron star transient heats the neutron star's crust out of thermal equilibrium with the core. After the outburst the crust thermally relaxes toward equilibrium with the neutron star core and the surface thermal emission powers the quiescent X-ray light curve. Crust cooling models predict that thermal equilibrium of the crust will be established $\\approx 1000 \\, \\mathrm{d}$ into quiescence. Recent observations of the cooling neutron star transient MXB 1659-29, however, suggest that the crust did not reach thermal equilibrium with the core on the predicted timescale and continued to cool after $\\approx 2500 \\, \\mathrm{d}$ into quiescence. Because the quiescent light curve reveals successively deeper layers of the crust, the observed late time cooling of MXB 1659-29 depends on the thermal transport in the inner crust. In particular, the observed late time cooling is consistent with a low thermal conductivity layer near the depth predicted for nuclear pasta that maintains a temperat...
Late time observations of GRB080319B: jet break, host galaxy and accompanying supernova
Tanvir, Nial R; Levan, Andrew; Fruchter, Andrew; Granot, Jonathan; Svensson, Karl M; O'Brien, Paul T; Wiersema, Klaas; Starling, Rhaana L C; Jakobsson, Pall; Fynbo, Johan; Hjorth, Jens; Curran, Peter; van der Horst, Alexander J; Kouveliotou, Chryssa; Racusin, Judith L; Burrows, David N; Genet, Frank
2008-01-01
The Swift-discovered GRB080319B was by far the most distant source ever observed at naked eye brightness, reaching a peak magnitude of 5.3 at a redshift of z=0.937. We present our late time optical and X-ray observations, which confirm that an achromatic break occurred in the power-law afterglow light curve at ~10^6 s post-burst. This most likely indicates that the gamma-ray burst (GRB) outflow was collimated, which for a uniform jet would imply a total energy in the jet E_{jet} \\gsim 10^{52.5} erg. Our observations also show a late-time excess of red light, which is well explained if the GRB was accompanied by a supernova, similar to those seen in some other long-duration GRBs. The latest observations are dominated by light from the host and show that the GRB took place in a faint dwarf galaxy (r(AB) = 27.2, rest-frame M_B = -17.3). This galaxy is small even by the standards of other GRB hosts, which is suggestive of a low metallicity environment.
Late-time quantum backreaction of a very light nonminimally coupled scalar
Glavan, Dražen; Prokopec, Tomislav; Takahashi, Tomo
2016-10-01
We investigate the backreaction of the quantum fluctuations of a very light (m ≲Htoday) nonminimally coupled spectator scalar field on the expansion dynamics of the Universe. The one-loop expectation value of the energy-momentum tensor of these fluctuations, as a measure of the backreaction, is computed throughout the expansion history from the early inflationary universe until the onset of recent acceleration today. We show that, when the nonminimal coupling ξ to Ricci curvature is negative (ξc=1 /6 corresponding to conformal coupling), the quantum backreaction grows exponentially during inflation, such that it can grow large enough rather quickly (within a few hundred e -foldings) to survive until late time and constitute a contribution of the cosmological constant type of the right magnitude to appreciably alter the expansion dynamics. The unique feature of this model is in that, under rather generic assumptions, inflation provides a natural explanation for the initial conditions needed to explain the late-time accelerated expansion of the Universe, making it a particularly attractive model of dark energy.
On the Late-Time Behavior of Virasoro Blocks and a Classification of Semiclassical Saddles
Fitzpatrick, A Liam
2016-01-01
Recent work has demonstrated that black hole thermodynamics and information loss/restoration in AdS$_3$/CFT$_2$ can be derived almost entirely from the behavior of the Virasoro conformal blocks at large central charge, with relatively little dependence on the precise details of the CFT spectrum or OPE coefficients. Here, we elaborate on the non-perturbative behavior of Virasoro blocks by classifying all `saddles' that can contribute for arbitrary values of external and internal operator dimensions in the semiclassical large central charge limit. The leading saddles, which determine the naive semiclassical behavior of the Virasoro blocks, all decay exponentially at late times, and at a rate that is independent of internal operator dimensions. Consequently, the semiclassical contribution of high-energy states does not resolve a well-known version of the information loss problem in AdS$_3$. However, we identify two infinite classes of sub-leading saddles, and one of these classes does not decay at late times.
Pseudo analytical solution to time periodic stiffness systems
Institute of Scientific and Technical Information of China (English)
Wang Yan-Zhong; Zhou Yuan-Zi
2011-01-01
An analytical form of state transition matrix for a system of equations with time periodic stiffness is derived in order to solve the free response and also allow for the determination of system stability and bifurcation. A pseudoclosed form complete solution for parametrically excited systems subjected to inhomogeneous generalized forcing is developed, based on the Fourier expansion of periodic matrices and the substitution of matrix exponential terms via Lagrange-Sylvester theorem. A Mathieu type of equation with large amplitude is presented to demonstrate the method of formulating state transition matrix and Floquet multipliers. A two-degree-of-freedom system with irregular time periodic stiffness characterized by spiral bevel gear mesh vibration is presented to find forced response in stability and instability. The obtained results are presented and discussed.
Cast iron deterioration with time in various aqueous salt solutions
Indian Academy of Sciences (India)
Rita Mehra; Aditi Soni
2002-02-01
The changes with time in the corrosion rate and corrosion current density on a cast iron electrode in various aqueous salt solutions have been carried out using total immersion test and potentiostatic polarization curves. The concentration of salts taken is expected to be present in potable water. The relative behaviour of these salts towards corrosion has also been studied, which is found to be different from previous studies. The total immersion test parameters viz. weight loss, corrosion rate as well as potentiostatic parameters, open circuit potential, corr, Tafel slopes, corrosion rate, have been calculated by standard methods. Besides these the relative increase in corrosion rate with time as well as the percentage to which corrosion rate should be decreased so as to provide protection towards corrosion have also been calculated. It was found that KCl and NaCl are major contributors than MnSO4, Pb(NO3)2, KI and KBr. The relative increase in corrosion is high in KBr, KI, NaNO3, CaCl2, and less in Pb(NO3)2, NaHCO3 and CaCO3 test solutions. For the reliability of results the data has been statistically analysed.
Late-time behaviour of Israel particles in a FLRW spacetime with Λ > 0
Lee, Ho; Nungesser, Ernesto
2017-07-01
In this paper we study the space-homogeneous Boltzmann equation in a spatially flat FLRW spacetime. We consider Israel particles, which are the relativistic counterpart of the Maxwellian particles, and obtain global-in-time existence and the asymptotic behaviour of solutions. The main argument of the paper is to use the energy method of Guo, and we observe that the method can be applied to study small solutions in a cosmological case. It is the first result of this type where a physically well-motivated scattering kernel is considered for the general relativistic Boltzmann equation.
Exact solutions of the time-fractional Fisher equation by using modified trial equation method
Tandogan, Yusuf Ali; Bildik, Necdet
2016-06-01
In this study, modified trial equation method has been proposed to obtain precise solutions of nonlinear fractional differential equation. Using the modified test equation method, we obtained some new exact solutions of the time fractional nonlinear Fisher equation. The obtained results are classified as a soliton solution, singular solutions, rational function solutions and periodic solutions.
Experimental investigation of late time Rayleigh-Taylor mixing at high Atwood number
Suchandra, Prasoon; Mikhaeil, Mark; Ranjan, Devesh
2016-11-01
Dynamics of late time, high Reynolds number (Re >20000) Rayleigh-Taylor (RT) mixing is studied using statistically steady experiments performed in a multi-layer gas tunnel. The density ratio of air and air-Helium mixture used in the present experiment results in an Atwood number 0.73. Three types of diagnostics - back-lit visualization, hot-wire anemometry and stereo particle image velocimetry (S-PIV) - are employed to obtain mixing width, velocity and density fields, with S-PIV employed for the first time for such experimental conditions. Velocity and density statistics, and their correlations (u', v', w',ρ' ,ρ'v') are presented. Calculations of probability density functions (p.d.f.s) and energy spectra are made to provide further insight into the flow physics. Energy budget of the flow is also discussed.
Energy Technology Data Exchange (ETDEWEB)
Setare, M.R. [Department of Science, Campus of Bijar, University of Kurdistan,Bijar (Iran, Islamic Republic of); Sepehri, A. [Faculty of Physics, Shahid Bahonar University,P.O. Box 76175, Kerman (Iran, Islamic Republic of)
2015-03-16
In this paper, we consider the stability of cylindrical wormholes during evolution of universe from inflation to late time acceleration epochs. We show that there are two types of cylindrical wormholes. The first type is produced at the corresponding point where k black F-strings are transited to BIon configuration. This wormhole transfers energy from extra dimensions into our universe, causes inflation, loses it’s energy and vanishes. The second type of cylindrical wormhole is created by a tachyonic potential and causes a new phase of acceleration. We show that wormhole parameters grow faster than the scale factor in this era, overtake it at ripping time and lead to the destruction of universe at big rip singularity.
String solutions in $AdS_3\\times S^3\\times S^3\\times S^1$ with $B$-field
Bozhilov, Plamen
2016-01-01
We consider strings living in $AdS_3\\times S^3\\times S^3\\times S^1$ with nonzero $B$-field. By using specific ansatz for the string embedding, we obtain a class of solutions corresponding to strings moving in the whole ten dimensional space-time. For the $AdS_3$ subspace, these solutions are given in terms of incomplete elliptic integrals. For the two three-spheres, they are expressed in terms of Lauricella hypergeometric functions of many variables. The conserved charges, i.e. the string energy, spin and angular momenta, are also found.
Time Resolved X-Ray Scattering of molecules in Solution
DEFF Research Database (Denmark)
Brandt van Driel, Tim
The dissertation describes the use of Time-Resolved X-ray Diffuse Scattering (TR-XDS) to study photo-induced structural changes in molecules in solution. The application of the technique is exemplified with experiments on two bimetallic molecules. The main focus is on the data-flow and process...... of bringing the data from measurement to analysis. Bridging the experimental design and challenges of the experiments from X-ray synchrotrons to the newly available X-ray Free Electron Laser sources (XFEL).LCLS in California is the first XFEL to come online and delivers intense 30fs X-ray pulses, orders...... of magnitude shorter than the 100ps X-ray pulses available from synchroton sources. This increase in time-resolution allows for the use of X-ray techniques in a completely new time-domain, where coherent photo-induced changes in structure can be studied on their intrinsic time-scale. Measurements on Rh2(dimen...
Detailed Analysis of Early to Late-Time Spectra of Supernova 1993J
Matheson, T; Ho, L C; Barth, A J; Leonard, D C; Matheson, Thomas; Filippenko, Alexei V.; Ho, Luis C.; Barth, Aaron J.; Leonard, Douglas C.
2000-01-01
We present a detailed study of line structure in early to late-time spectra of Supernova (SN) 1993J. Spectra during the nebular phase, but within the first two years after explosion, exhibit small-scale structure in the emission lines of some species, notably oxygen and magnesium, showing that the ejecta of SN 1993J are clumpy. On the other hand, a lack of structure in emission lines of calcium implies that the source of calcium emission is uniformly distributed throughout the ejecta. These results are interpreted as evidence that oxygen emission originates in clumpy, newly synthesized material, while calcium emission arises from material pre-existing in the atmosphere of the progenitor. Spectra spanning the range 433-2454 days after the explosion show box-like profiles for the emission lines, clearly indicating circumstellar interaction in a roughly spherical shell. This is interpreted within the Chevalier & Fransson (1994) model for SNe interacting with mass lost during prior stellar winds. At very late...
Rif1 regulates initiation timing of late replication origins throughout the S. cerevisiae genome.
Directory of Open Access Journals (Sweden)
Jared M Peace
Full Text Available Chromosomal DNA replication involves the coordinated activity of hundreds to thousands of replication origins. Individual replication origins are subject to epigenetic regulation of their activity during S-phase, resulting in differential efficiencies and timings of replication initiation during S-phase. This regulation is thought to involve chromatin structure and organization into timing domains with differential ability to recruit limiting replication factors. Rif1 has recently been identified as a genome-wide regulator of replication timing in fission yeast and in mammalian cells. However, previous studies in budding yeast have suggested that Rif1's role in controlling replication timing may be limited to subtelomeric domains and derives from its established role in telomere length regulation. We have analyzed replication timing by analyzing BrdU incorporation genome-wide, and report that Rif1 regulates the timing of late/dormant replication origins throughout the S. cerevisiae genome. Analysis of pfa4Δ cells, which are defective in palmitoylation and membrane association of Rif1, suggests that replication timing regulation by Rif1 is independent of its role in localizing telomeres to the nuclear periphery. Intra-S checkpoint signaling is intact in rif1Δ cells, and checkpoint-defective mec1Δ cells do not comparably deregulate replication timing, together indicating that Rif1 regulates replication timing through a mechanism independent of this checkpoint. Our results indicate that the Rif1 mechanism regulates origin timing irrespective of proximity to a chromosome end, and suggest instead that telomere sequences merely provide abundant binding sites for proteins that recruit Rif1. Still, the abundance of Rif1 binding in telomeric domains may facilitate Rif1-mediated repression of non-telomeric origins that are more distal from centromeres.
Gao, Min-Rui; Jiang, Jun; Yu, Shu-Hong
2012-01-09
Late transition metal chalcogenide (LTMC) nanomaterials have been introduced as a promising Pt-free oxygen reduction reaction (ORR) electrocatalysts because of their low cost, good ORR activity, high methanol tolerance, and facile synthesis. Herein, an overview on the design and synthesis of LTMC nanomaterials by solution-based strategies is presented along with their ORR performances. Current solution-based synthetic approaches towards LTMC nanomaterials include a hydrothermal/solvothermal approach, single-source precursor approach, hot-injection approach, template-directed soft synthesis, and Kirkendall-effect-induced soft synthesis. Although the ORR activity and stability of LTMC nanomaterials are still far from what is needed for practical fuel-cell applications, much enhanced electrocatalytic performance can be expected. Recent advances have emphasized that decorating the surface of the LTMC nanostructures with other functional nanoparticles can lead to much better ORR catalytic activity. It is believed that new synthesis approaches to LTMCs, modification techniques of LTMCs, and LTMCs with desirable morphology, size, composition, and structures are expected to be developed in the future to satisfy the requirements of commercial fuel cells.
Wormholes versus black holes: quasinormal ringing at early and late times
Konoplya, R A
2016-01-01
Recently it has been argued that a special type of the thin-shell wormholes matched with the Schwarzschild space-time near the Schwarzschild radius produces quasinormal ringing, which coincides with the Schwarzschild one's at early times, but different at late times (arXiv:1602.07309). Here we consider perturbations of the wormhole configuration in General Relativity, constructed without thin-shells (the Bronnikov-Ellis wormhole supported by the phantom dust and electromagnetic field) and its generalizations, in order to show that if one does not use the above, particular thin-shell "tailoring", the wormhole, depending on values of its parameters, either rings as the black hole at all times or rings differently also at all times. The wormhole's spectrum, investigated here, posses a number of distinctive features. The s-mode of the Bronnikov-Ellis wormhole, corresponding to the phantom dust perturbation, rings effectively like a massive field. We have also studied properties of the scattering around generic ax...
Optical and ultraviolet spectroscopic analysis of SN 2011fe at late times
Friesen, Brian; Parrent, Jerod T; Thomas, R C; Branch, David; Nugent, Peter; Hauschildt, Peter H; Foley, Ryan J; Wright, Darryl E; Pan, Yen-Chen; Filippenko, Alexei V; Clubb, Kelsey I; Silverman, Jeffrey M; Maeda, Keiichi; Shivvers, Isaac; Kelly, Patrick L; Cohen, Daniel P; Rest, Armin; Kasen, Daniel
2016-01-01
We present optical spectra of the nearby Type Ia supernova SN 2011fe at 100, 205, 311, 349, and 578 days post-maximum light, as well as an ultraviolet spectrum obtained with Hubble Space Telescope at 360 days post-maximum light. We compare these observations with synthetic spectra produced with the radiative transfer code PHOENIX. The day +100 spectrum can be well fit with models which neglect collisional and radiative data for forbidden lines. Curiously, including this data and recomputing the fit yields a quite similar spectrum, but with different combinations of lines forming some of the stronger features. At day +205 and later epochs, forbidden lines dominate much of the optical spectrum formation; however, our results indicate that recombination, not collisional excitation, is the most influential physical process driving spectrum formation at these late times. Consequently, our synthetic optical and UV spectra at all epochs presented here are formed almost exclusively through recombination-driven fluore...
Avants, Brian B; Hackman, Daniel A; Betancourt, Laura M; Lawson, Gwendolyn M; Hurt, Hallam; Farah, Martha J
2015-01-01
What are the long-term effects of childhood experience on brain development? Research with animals shows that the quality of environmental stimulation and parental nurturance both play important roles in shaping lifelong brain structure and function. Human research has so far been limited to the effects of abnormal experience and pathological development. Using a unique longitudinal dataset of in-home measures of childhood experience at ages 4 and 8 and MRI acquired in late adolescence, we were able to relate normal variation in childhood experience to later life cortical thickness. Environmental stimulation at age 4 predicted cortical thickness in a set of automatically derived regions in temporal and prefrontal cortex. In contrast, age 8 experience was not predictive. Parental nurturance was not predictive at either age. This work reveals an association between childhood experience and later brain structure that is specific relative to aspects of experience, regions of brain, and timing.
Limits in late time conversion of cold dark matter into hot dark matter
Motta, M; de Holanda, P C
2013-01-01
Structure formation creates high temperature and density regions in the Universe that allow the conversion of matter into more stable states, with a corresponding emission of relativistic matter and radiation. An example of such a mechanism is the supernova event, that releases relativistic neutrinos corresponding to 99% of the binding energy of remnant neutron star. We take this phenomena as a starting point for an assumption that similar processes could occur in the dark sector, where structure formation would generate a late time conversion of cold dark matter into a relativistic form of dark matter. We performed a phenomenological study about the limits of this conversion, where we assumed a transition profile that is a generalized version of the process responsible for the neutrino production in supernovae events. With this assumption, we obtained interesting modifications for the constraints over some parameters such as the dark energy equation of state and the cold dark matter density. We show that whe...
Generalized $f(R,\\phi,X)$ gravity and the late-time cosmic acceleration
Beltran, Sebastian Bahamonde; Lobo, Francisco S N; Saez-Gomez, Diego
2015-01-01
High-precision observational data have confirmed with startling evidence that the Universe is currently undergoing a phase of accelerated expansion. This phase, one of the most important and challenging current problems in cosmology, represents a new imbalance in the governing gravitational equations. Historically, physics has addressed such imbalances by either identifying sources that were previously unaccounted for, or by altering the gravitational theory. Several candidates, responsible for this expansion, have been proposed in the literature, in particular, dark energy models and modified gravity models, amongst others. Outstanding questions are related to the nature of this so-called "dark energy" that is driving this acceleration, and whether it is due to the vacuum energy or a dynamical field. On the other hand, the late-time cosmic acceleration may be due to modifications of General Relativity. In this work we explore a generalised modified gravity theory, namely $f(R,\\phi,X)$ gravity, where $R$ is t...
Late-time quantum backreaction of a very light nonminimally coupled scalar
Glavan, Dražen; Takahashi, Tomo
2015-01-01
We investigate the backreaction of the quantum fluctuations of a very light ($m \\!\\lesssim\\! H_{\\text{today}}$) nonminimally coupled spectator scalar field on the expansion dynamics of the Universe. The one-loop expectation value of the energy momentum tensor of these fluctuations, as a measure of the backreaction, is computed throughout the expansion history from the early inflationary universe until the onset of recent acceleration today. We show that, when the nonminimal coupling $\\xi$ to Ricci curvature is negative ($\\xi_c \\!=\\! 1/6$ corresponding to conformal coupling), the quantum backreaction grows exponentially during inflation, such that it can grow large enough rather quickly (within a few hundred e-foldings) to survive until late time and constitute a contribution of the cosmological constant type of the right magnitude to appreciably alter the expansion dynamics. The unique feature of this model is in that, under rather generic assumptions, inflation provides natural explanation for the initial co...
Looking for activity cycles in late-type Kepler stars using time-frequency analysis
Vida, K; Szabó, R
2014-01-01
We analyse light curves covering four years of 39 fast-rotating ($P_\\mathrm{rot}< 1d$) late-type active stars from the Kepler database. Using time-frequency analysis (Short-Term Fourier-Transform), we find hints for activity cycles of 300-900 days at 9 targets from the changing typical latitude of the starspots, which, with the differential rotation of the stellar surface change the observed rotation period over the activity cycle. We also give a lowest estimation for the shear parameter of the differential rotation, which is ~0.001 for the cycling targets. These results populate the less studied, short period end of the rotation-cycle length relation.
Extracting the late-time kinetic Sunyaev-Zel'dovich effect
Munshi, D.; Iliev, I. T.; Dixon, K. L.; Coles, P.
2016-12-01
We propose a novel technique to separate the late-time, post-reionization component of the kinetic Sunyaev-Zeldovich (kSZ) effect from the contribution to it from a (poorly understood and probably patchy) reionization history. The kSZ effect is one of the most promising probe of the missing baryons in the Universe. We study the possibility of reconstructing it in three dimensions (3D), using future spectroscopic surveys such as the Euclid survey. By reconstructing a 3D template from galaxy density and peculiar velocity fields from spectroscopic surveys we cross-correlate the estimator against CMB maps. The resulting cross-correlation can help us to map out the kSZ contribution to CMB in 3D as a function of redshift thereby extending previous results which use tomographic reconstruction. This allows the separation of the late-time effect from the contribution owing to reionization. By construction, it avoids contamination from foregrounds, primary CMB, tSZ effect as well as from star-forming galaxies. Due to a high number density of galaxies the signal-to-noise ratio (S/N) for such cross-correlational studies is higher, compared to the studies involving CMB power-spectrum analysis. Using a spherical Bessel-Fourier (sFB) transform we introduce a pair of 3D power spectra: C^{allel }_ℓ (k) and C^{perp }_ℓ (k) that can be used for this purpose. We find that in a future spectroscopic survey with near all-sky coverage and a survey depth of z ≈ 1, reconstruction of C^{perp }_ℓ (k) can be achieved in a few radial wave bands k ≈ (0.01-0.5 h- 1 Mpc) with a S/N ratio of up to O(10) for angular harmonics in the range ℓ = (200-2000).
The early and late-time spectral and temporal evolution of GRB 050716
Rol, E; Page, K L; McGowan, K E; Beardmore, A P; O'Brien, P T; Levan, A J; Bersier, D; Guidorzi, C; Marshall, F; Fruchter, A S; Tanvir, N R; Monfardini, A; Gomboc, A; Barthelmy, S; Bannister, N P
2006-01-01
We report on a comprehensive set of observations of Gamma Ray Burst 050716, detected by the Swift satellite and subsequently followed-up rapidly in X-ray, optical and near infra-red wavebands. The prompt emission is typical of long-duration bursts, with two peaks in a time interval of T90 = 68 seconds (15 - 350 keV). The prompt emission continues at lower flux levels in the X-ray band, where several smaller flares can be seen, on top of a decaying light curve that exhibits an apparent break around 220 seconds post trigger. This temporal break is roughly coincident with a spectral break. The latter can be related to the extrapolated evolution of the break energy in the prompt gamma-ray emission, and is possibly the manifestation of the peak flux break frequency of the internal shock passing through the observing band. A possible 3 sigma change in the X-ray absorption column is also seen during this time. The late-time afterglow behaviour is relatively standard, with an electron distribution power-law index of ...
Zhang, Jianmin; Taylor, Russell J; La Torre, Anna; Wilken, Matthew S; Cox, Kristen E; Reh, Thomas A; Vetter, Monica L
2015-07-15
Epigenetic regulation, including histone modification, is a critical component of gene regulation, although precisely how this contributes to the development of complex tissues such as the neural retina is still being explored. We show that during retinal development in mouse, there are dynamic patterns of expression of the polycomb repressive complex 2 (PRC2) catalytic subunit EZH2 in retinal progenitors and some differentiated cells, as well as dynamic changes in the histone modification H3K27me3. Using conditional knockout of Ezh2 using either Pax6-αCre or Six3-Cre, we find selective reduction in postnatal retinal progenitor proliferation, disruption of retinal lamination, and enhanced differentiation of several late born cell types in the early postnatal retina, including photoreceptors and Müller glia, which are ultimately increased in number and become reactive. RNA-seq identifies many non-retinal genes upregulated with loss of Ezh2, including multiple Hox genes and the cell cycle regulator Cdkn2a, which are established targets of EZH2-mediated repression. ChIP analysis confirms loss of the H3K27me3 modification at these loci. Similar gene upregulation is observed in retinal explants treated with an EZH2 chemical inhibitor. There is considerable overlap with EZH2-regulated genes reported in non-neural tissues, suggesting that EZH2 can regulate similar genes in multiple lineages. Our findings reveal a conserved role for EZH2 in constraining the expression of potent developmental regulators to maintain lineage integrity and retinal progenitor proliferation, as well as regulating the timing of late differentiation. Copyright © 2015 Elsevier Inc. All rights reserved.
Late-time near-infrared observations of SN 2005df
Diamond, Tiara; Gerardy, Christopher L
2014-01-01
We present late-time ($200-400$ days) near-infrared spectral evolution for the Type Ia supernova SN 2005df. The spectra show numerous strong emission features of [CoII], [CoIII], and [FeII] throughout the $0.8-1.8$\\mu m region. As the spectrum ages, the cobalt features fade as would be expected from the decay of $^{56}$Co to $^{56}$Fe. We show that the strong and isolated [FeII] emission line at $1.644$\\mu m provides a unique tool to analyze near-infrared spectra of Type Ia supernovae. Normalization of spectra to this line allows separation of features produced by stable versus unstable isotopes of iron group elements. We develop a new method of determining the initial central density, $\\rho_c$, and the magnetic field, $B$, of the white dwarf using the width of the $1.644$\\mu m line. The line width is sensitive because of electron capture in the early stages of burning, which increases as a function of density. The sensitivity of the line width to $B$ increase with time and the effects of the magnetic field s...
Long time-scale variability of X-ray binaries with late type giant companions
Filippova, E; Parkin, E R
2013-01-01
In this paper we propose and examine a physical mechanism which can lead to the generation of noise in the mass accretion rate of low mass X-ray binaries on time-scales comparable to the orbital period of the system. We consider modulations of mass captured by the compact object from the companion star's stellar wind in binaries with late type giants, systems which usually have long orbital periods. We show that a hydrodynamical interaction of the wind matter within a binary system even without eccentricity results in variability of the mass accretion rate with characteristic time-scales close to the orbital period. The cause of the variability is an undeveloped turbulent motion (perturbed motion without significant vorticity) of wind matter near the compact object. Our conclusions are supported by 3D simulations with two different hydrodynamic codes based on Lagrangian and Eulerian approaches -- the SPH code GADGET and the Eulerian code PLUTO. In this work we assume that the wind mass loss rate of the second...
The timing of Late Pleistocene glaciation at Mount Wilhelm, Papua New Guinea
Mills, Stephanie; Barrows, Timothy; Hope, Geoff; Pillans, Brad; Fifield, Keith
2016-04-01
The highlands of New Guinea were the most extensively glaciated area in the Asian tropical region during the Late Pleistocene. Evidence for glaciation is widespread on most of the mountain peaks above ~3500 m. Glacial landforms include both valley and ice cap forms, but the timing of glaciation remains constrained to only a few local areas. This paper focuses on Mount Wilhelm, which is situated in the central southern region of Papua New Guinea at 5.78°S and is the highest peak (4510 m a.s.l.) We focus on a south easterly valley (Pindaunde Valley) emanating from the peak, where large moraines indicate the maximum ice extent of a valley glacier ~5 km long. Within this extensive moraine complex, recessional moraines document the retreat of the glacier towards the summit region. In order to determine the timing of deglaciation, we collected samples for surface exposure dating using 36Cl and 10Be from diorite boulders positioned on moraine crests. The ages indicate that maximum ice extent was attained during the last glacial maximum (LGM) and that ice remained near its maximum extent until after 15 ka but persisted at higher elevations almost until the Holocene. These results are similar to those described from Mt Giluwe to the northwest of Mount Wilhelm, where an ice cap reached its maximum extent at the LGM and remained there for around 3-4,000 years. This indicates that full glacial conditions were only brief in this region of the tropics.
ScalPy: A Python Package For Late Time Scalar Field Cosmology
Kumar, Sumit; Sen, Anjan A
2015-01-01
We present a python package "ScalPy" for studying the late time scalar field cosmology for a wide variety of scalar field models, namely the quintessence, tachyon and Galileon model. The package solves the autonomous system of equations for power law and exponential potential. But it can be easily generalized to add more complicated potential. For completeness, we also include the standard parameterization for dark energy models, e.g. the $\\Lambda$CDM, $w$CDM, $w_{0}w_{a}$CDM as well as the GCG parameterization. The package also solves the linear growth equation for matter perturbations on sub-horizon scales. All the important observables related to background universe as well as to the perturbed universe, e.g. luminosity distance ($D_{L}(z)$), angular diameter distance ($D_{A}(z)$), normalized Hubble parameter ($h(z)$), lookback time ($t_{L}$), equation of state for the dark energy ($w(z)$), growth rate ($f=\\frac{d \\ln\\delta}{d \\ln a}$), linear matter power spectra ($P(k)$), and its normalization $\\sigma_{8}...
Late-time Domain Growth in the Compressible Triangular Ising Net
Meng, Meng; Landau, David
2012-02-01
We perform large scale Monte Carlo simulations of the long-tme domain growth behavior in a compressible, triangular Ising net. Unlike previous work,ootnotetextMitchell and DP Landau, PRL 97, 025701 (2006) our model has no bond angle interactions or lattice mismatch. The system is quenched below the critical temperature from a homogenous disordered state to an ordered phase where multiple domains coexist. We include an elastic energy part in the Hamiltonian to adjust the rigidity of the model. Theory expects the domain size R(t) grows as a power law R(t)=A+Bt^n, where t is the time after the quench. For the rigid model we find the late-time domain size growth factor n has Lifshitz-Slozov value of 13. For weak flexible models, we get slight reduction from 13. For the strongly flexible model, we get a bimodal distribution of bond lengths and a dramatically reduced value of n, which has similar behavior as the mismatch model.ootnotetextIbid.
Are Some Asteroid Families From The Time Of The Late Heavy Bombardment?
Morbidelli, Alessandro; Brasser, R.; Nesvorny, D.; Vokrouhlicky, D.; Bottke, W. F.
2010-10-01
The Late Heavy Bombardment (LHB) of the Moon 3.8 Gy ago was presumably a global event that affected the main belt asteroids as well. We do see indeed a spike in meteorite shock ages 3.8Gy ago (Kring and Swindle, 2008). Thus, we would expect that several asteroid families formed at that time. Our work on the evolution of the giant planets at the LHB-time implies that the asteroid orbits were affected less than previously thought (Morbidelli et al., DPS2009). Thus, while families that formed before or during the LHB would have been significantly dispersed in eccentricity (e) and inclination (i), they should still be recognizable today. From an analysis of the color distribution, Parker et al. (2008) showed that some asteroid families are much more dispersed in e and i than the "core" families identified from proper elements clustering. We propose here that at least some of these families formed during the LHB. As an example, we focus on the Eos family. Vokrouhlicky et al. (2006) showed that the confinement of this family within mean motion resonances requires an initial velocity dispersion <80m/s. Yet, using this initial dispersion, the subsequent evolution in the current solar system produces an (e,i) dispersion that is only half of that observed in the "core" family. In addition, the SDSS colors suggest that the real dispersion of the family is 2-3 times larger than the "core". So, there is definitely a problem in understanding the (e,i) dispersion of the Eos family. We show that a break-up event with a velocity dispersion <80m/s at the time of the LHB can easily result in a family with an identifiable core and a full dispersion comparable to that observed for objects matching Eos' color.
Late-time quadratic growth in single-mode Rayleigh-Taylor instability.
Wei, Tie; Livescu, Daniel
2012-10-01
The growth of the two-dimensional single-mode Rayleigh-Taylor instability (RTI) at low Atwood number (A=0.04) is investigated using Direct Numerical Simulations. The main result of the paper is that, at long times and sufficiently high Reynolds numbers, the bubble acceleration becomes stationary, indicating mean quadratic growth. This is contrary to the general belief that single-mode Rayleigh-Taylor instability reaches a constant bubble velocity at long times. At unity Schmidt number, the development of the instability is strongly influenced by the perturbation Reynolds number, defined as Rep≡λsqrt[Agλ/(1+A)]/ν. Thus, the instability undergoes different growth stages at low and high Rep. A new stage, chaotic development, was found at sufficiently high Rep values, after the reacceleration stage. During the chaotic stage, the instability experiences seemingly random acceleration and deceleration phases, as a result of complex vortical motions, with strong dependence on the initial perturbation shape (i.e., wavelength, amplitude, and diffusion thickness). Nevertheless, our results show that the mean acceleration of the bubble front becomes constant at late times, with little influence from the initial shape of the interface. As Rep is lowered to small values, the later instability stages, chaotic development, reacceleration, potential flow growth, and even the exponential growth described by linear stability theory, are subsequently no longer reached. Therefore, the results suggest a minimum Reynolds number and a minimum development time necessary to achieve all stages of single-mode RTI development, requirements which were not satisfied in the previous studies of single-mode RTI.
Time-periodic Solution to a Nonlinear Parabolic Type Equation of Higher Order
Institute of Scientific and Technical Information of China (English)
Yan-ping Wang; You-lin Zhang
2008-01-01
In this paper, the existence and uniqueness of time-periodic generalized solutions and time-periodic classical solutions to a class of parabolic type equation of higher order are proved by Gaierkin method.
Time-Periodic Solution of a 2D Fourth-Order Nonlinear Parabolic Equation
Indian Academy of Sciences (India)
Xiaopeng Zhao; Changchun Liu
2014-08-01
By using the Galerkin method, we study the existence and uniqueness of time-periodic generalized solutions and time-periodic classical solutions to a fourth-order nonlinear parabolic equation in 2D case.
Chen, Wen-Yi
2016-09-01
This study investigates the casual linkage between economic conditions around the time of birth and late life cognitive abilities. The zero-inflated negative binomial and multivariate logistic regression models were used to evaluate the direct and indirect effect of economic conditions around the time of birth on late life cognitive abilities, respectively. Both direct and indirect effects of economic conditions around the time of birth on late life cognitive abilities were identified. The relative risk ratio in adjusted mean scores of the Short Portable Mental Status Questionnaire (a means to measure cognitive impairment) indicates that being born in an economic recession year (experiencing economic recession during the year prior to birth) increases the risk of difficulties with cognition by 17.40% (11.70%). Being born in an economic recession year decreases the likelihood of high educational attainment in later life by an odds ratio of 0.962. Copyright © 2016 Elsevier B.V. All rights reserved.
Limits in late time conversion of cold dark matter into dark radiation
Energy Technology Data Exchange (ETDEWEB)
Boriero, D.; Holanda, P. C. de; Motta, M., E-mail: danielb@ifi.unicamp.br, E-mail: holanda@ifi.unicamp.br, E-mail: mmota@ifi.unicamp.br [Instituto de Física Gleb Wataghin – UNICAMP, 13083-859, Campinas SP (Brazil)
2013-06-01
Structure formation creates high temperature and density regions in the Universe that allow the conversion of matter into more stable states, with a corresponding emission of relativistic matter and radiation. An example of such a mechanism is the supernova event, that releases relativistic neutrinos corresponding to 99% of the binding energy of remnant neutron star. We take this phenomena as a starting point for an assumption that similar processes could occur in the dark sector, where structure formation would generate a late time conversion of cold dark matter into a relativistic form of dark matter. We performed a phenomenological study about the limits of this conversion, where we assumed a transition profile that is a generalized version of the neutrino production in supernovae events. With this assumption, we obtained an interesting modification for the constraint over the cold dark matter density. We show that when comparing with the standard ΛCDM cosmology, there is no preference for conversion, although the best fit is within 1σ from the standard model best fit. The methodology and the results obtained qualify this conversion hypothesis, from the large scale structure point of view, as a viable and interesting model to be tested in the future with small scale data, and mitigate discrepancies between observations at this scale and the pure cold dark matter model.
Thermonuclear Supernovae: Probing Magnetic Fields by Late-Time IR Line Profiles
Penney, R
2014-01-01
We study the imprint of magnetic fields B on late-time IR line profiles and light curves of Type Ia Supernovae. As a benchmark, we use the explosion of a Chandrasekhar mass M_{Ch White Dwarf (WD) and, specifically, a delayed detonation model. We assume WDs with initial magnetic surface fields between 1 and 1E9G. We discuss large-scale dipole and small-scale magnetic fields. We find that the [Fe II] line at 1.644 mu can be used to analyze the overall chemical and density structure of the exploding WD up to day 200 without considering B. Subsequently, positron transport and magnetic field effects become important. By day 500, the profile becomes sensitive to the morphology of B and directional dependent for dipole fields. Small or no directional dependence of the spectra is found for small-scale B. After about 200 days, persistent broad-line, flat-topped or stumpy profiles require high density burning which is the signature of a WD close to M_Ch. Narrow peaked profiles are a signature of chemical mixing or sub-...
Directory of Open Access Journals (Sweden)
Simeon Metallidis
2012-10-01
Full Text Available Background: The aim of our study was to assess the extent of late presentation for HIV care in Northern Greece during the period 2000 to 2010 and to explore correlations aiming to provide guidance for future interventions. Methods: HIV-positive patients with no prior history of HIV care at presentation and with a CD4 T cell count within three months from the first confirmatory Western blot result were eligible for this study. Late presentation and advanced HIV disease were defined in concordance with the recommendations of the European Late Presenter Consensus working group. Time trends in presentation status and risk factors linked to late presentation and advanced HIV disease were identified in multivariable logistic regression models. Additional analyses after multiple imputation of missing values were performed to assess the robustness of our findings. Results: The status at presentation was evaluated for 631 eligible HIV-positive individuals. Overall, 52.5% (95% CI: 48.6% to 56.4% of patients presented late for HIV care and 31.2% (95% CI: 27.6% to 34.8% presented with advanced HIV disease. Time trends were consistent with an improvement in the presentation status of our study population (p<0.001. Risk factors associated with late presentation in multivariable logistic regression were intravenous drug use, heterosexual HIV transmission, immigrant status and age at diagnosis. Conclusions: Despite the trend for improvement, a significant proportion of newly diagnosed HIV-positive patients present late for care. Targeted interventions with focus on social groups such as the elderly, persons who inject drugs, immigrants and individuals at risk for heterosexual HIV transmission are mandated.
EXISTENCE OF TIME PERIODIC SOLUTIONS FOR A DAMPED GENERALIZED COUPLED NONLINEAR WAVE EQUATIONS
Institute of Scientific and Technical Information of China (English)
房少梅; 郭柏灵
2003-01-01
The time periodic solution problem of damped generalized coupled nonlinear wave equations with periodic boundary condition was studied. By using the Galerkin method to construct the approximating sequence of time periodic solutions, a priori estimate and Laray-Schauder fixed point theorem to prove the convergence of the approximate solutions, the existence of time periodic solutions for a damped generalized coupled nonlinear wave equations can be obtained.
Time-periodic solutions of the Einstein’s field equations Ⅰ:general framework
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In this paper,we develop a new algorithm to find the exact solutions of the Einstein’s field equations.Time-periodic solutions are constructed by using the new algorithm.The singularities of the time-periodic solutions are investigated and some new physical phenomena,such as degenerate event horizon and time-periodic event horizon,are found.The applications of these solutions in modern cosmology and general relativity are expected.
Travelling wave solutions for some time-delayed equations through factorizations
Energy Technology Data Exchange (ETDEWEB)
Fahmy, E.S. [King Saud University, Women Students Medical Studies and Sciences Sections, Mathematics Department, P.O. Box 22452, Riyadh 11495 (Saudi Arabia)], E-mail: esfahmy@operamail.com
2008-11-15
In this work, we use factorization method to find explicit particular travelling wave solutions for the following important nonlinear second-order partial differential equations: The generalized time-delayed Burgers-Huxley, time-delayed convective Fishers, and the generalized time-delayed Burgers-Fisher. Using the particular solutions for these equations we find the general solutions, two-parameter solution, as special cases.
Periodic Solutions of a Discrete Time Predator-Prey System
Institute of Scientific and Technical Information of China (English)
Yong-li Song; Mao-an Han
2006-01-01
In this paper, we discuss a discrete predator-prey system with a non-monotonic functional response,which models the dynamics of the prey and the predator having non-overlapping generations. By using the coincidence degree theory, sufficient conditions are obtained for the existence of positive periodic solutions.
DEFF Research Database (Denmark)
Kromann, Peter; Taipe, Arturo; Perez, Willmer G.
2009-01-01
Accumulated rainfall thresholds were studied in seven field experiments conducted in Ecuador and Peru for their value in timing applications of fungicide to control potato late blight, caused by Phytophthora infestans. Fungicide regimes based on accumulated rainfall thresholds ranging from 10 to ...
Effects of Video-Modeling on the Interaction Skills of First-Time Fathers of Late Preterm Infants
Benzies, Karen Marie; Magill-Evans, Joyce; Kurilova, Jana; Nettel-Aguirre, Alberto; Blahitka, Laurie; Lacaze-Masmonteil, Thierry
2013-01-01
This study evaluated the effects of an innovative educational--behavioral intervention for first-time fathers of late preterm (34-36 weeks' gestation) infants, with the aim of enhancing the infant's environment through strengthening fathers' skills in interaction with their young infant. Using a randomized controlled trial, fathers of 111 late…
Pavlova, Maria K.; Haase, Claudia M.; Silbereisen, Rainer K.
2011-01-01
Drawing on two nationally representative German studies (N[subscript 1] = 1744, N[subscript 2] = 759), we examined correlates of early, on-time, and late curfew autonomy, a retrospective indicator of behavioural autonomy, in young and middle adulthood (19-37 years of age). Adjustment in four domains was considered: educational attainment,…
ISPC effect is not observed when the word comes too late: A time course analysis
Directory of Open Access Journals (Sweden)
Nart Bedin Atalay
2014-12-01
Full Text Available The item-specific proportion congruency (ISPC effect is demonstrated by a smaller Stroop effect observed for mostly incongruent items compared to mostly congruent items. Currently, there is a continuing debate on whether conflict driven item-specific control processes or stimulus-response contingency learning account for the ISPC effect. In the present study, we conducted two experiments to investigate the time course of the ISPC effect with a stimulus onset asynchrony (SOA manipulation. Both negative and positive SOAs were used in order to manipulate the contingency learning between the word and the color dimensions. We also combined this SOA manipulation with a set size manipulation (Bugg & Hutchison, 2013 to moderate the contribution of contingency learning and item-specific processes to the observed ISPC effect. We expected that the change in the magnitude of the ISPC effect as a result of SOA would follow different patterns for the 2-item and 4-item set conditions. Results showed that the SOA manipulation influenced the ISPC effect. Specifically, when the word followed the color with a 200 ms delay, the observed ISPC effect was smaller, if at all present, than the ISPC effects in other negative and positive SOA conditions, regardless of set size. In conclusion, our results showed that the ISPC effect was not observed if the word arrived too late. We also conducted additional awareness and RT distribution analyses (delta plots to further investigate the ISPC effect. These analyses showed that a higher percentage of participants were aware of the ISPC manipulation in the 2-item set condition compared to the 4-item set condition. Delta plots revealed that the ISPC effect was smaller for fastest responses and increased as the responses got slower.
Bielski, Conrad; Lemoine, Guido; Syryczynski, Jacek
2009-09-01
High Performance Computing (HPC) hardware solutions such as grid computing and General Processing on a Graphics Processing Unit (GPGPU) are now accessible to users with general computing needs. Grid computing infrastructures in the form of computing clusters or blades are becoming common place and GPGPU solutions that leverage the processing power of the video card are quickly being integrated into personal workstations. Our interest in these HPC technologies stems from the need to produce near real-time maps from a combination of pre- and post-event satellite imagery in support of post-disaster management. Faster processing provides a twofold gain in this situation: 1. critical information can be provided faster and 2. more elaborate automated processing can be performed prior to providing the critical information. In our particular case, we test the use of the PANTEX index which is based on analysis of image textural measures extracted using anisotropic, rotation-invariant GLCM statistics. The use of this index, applied in a moving window, has been shown to successfully identify built-up areas in remotely sensed imagery. Built-up index image masks are important input to the structuring of damage assessment interpretation because they help optimise the workload. The performance of computing the PANTEX workflow is compared on two different HPC hardware architectures: (1) a blade server with 4 blades, each having dual quad-core CPUs and (2) a CUDA enabled GPU workstation. The reference platform is a dual CPU-quad core workstation and the PANTEX workflow total computing time is measured. Furthermore, as part of a qualitative evaluation, the differences in setting up and configuring various hardware solutions and the related software coding effort is presented.
Climate change relaxes the time constraints for late-born offspring in a long-distance migrant.
Tomotani, Barbara M; Gienapp, Phillip; Beersma, Domien G M; Visser, Marcel E
2016-09-28
Animals in seasonal environments need to fit their annual-cycle stages, such as moult and migration, in a tight schedule. Climate change affects the phenology of organisms and causes advancements in timing of these annual-cycle stages but not necessarily at the same rates. For migratory birds, this can lead to more severe or more relaxed time constraints in the time from fledging to migration, depending on the relative shifts of the different stages. We tested how a shift in hatch date, which has advanced due to climate change, impacts the organization of the birds' whole annual cycle. We experimentally advanced and delayed the hatch date of pied flycatcher chicks in the field and then measured the timing of their annual-cycle stages in a controlled laboratory environment. Hatch date affected the timing of moult and pre-migratory fattening, but not migration. Early-born birds hence had a longer time to fatten up than late-born ones; the latter reduced their interval between onset of fattening and migration to be able to migrate at the same time as the early-born birds. This difference in time constraints for early- and late-born individuals may explain why early-born offspring have a higher probability to recruit as a breeding bird. Climate change-associated advancements of avian egg-lay dates, which in turn advances hatch dates, can thus reduce the negative fitness consequences of reproducing late, thereby reducing the selection for early egg-laying migratory birds.
Prevosti, Francisco; Santiago, Fernando; Prates, Luciano; Salemme, Mónica; Martin, Fabiana
2010-05-01
The mass extinction at the end of the Pleistocene affected South America during the Late Pleistocene and the Early Holocene, when megamammals and large mammals disappeared. Several carnivores became extinct, like the sabretooth Smilodon, the short face bear (Arctotherium) and some large canids (i.e. Protocyon, Canis dirus). After this mass event virtually no carnivores became extinct in South America. The only exception is the fox Dusicyon avus, a middle sized canid (estimated body mass between 10-15 kg) with a more carnivore diet than the living South American foxes (i.e. Lycalopex culpaeus). The last record of the species comes from middle-late Holocene archaeological sites in the Pampean Region (Argentina) and Patagonia (Argentina and Chile). During the Late Pleistocene D. avus had a wide distribution, that covered part of Uruguay, Argentina (Buenos Aires province) and the southernmost Chile. Albeit some remains from late Holocene sites have been published, these remains lack of isotopic dates that could (allow?) constraint (to determine) the date of extinction of this fox. In this contribution we present several new records from the Pampean Region and Patagonia, and several taxon dates. The new records indicate that D. avus disappeared in the late Holocene at least ≈ 3000 years BP in the island of Tierra del Fuego (Patagonia) and ≈ 1600 BP in the continent. Since at this time humans were occupying most of the Pampas and Patagonia a revision of the causes behind the extinction of this fox is required.
Solution Estimates for Semilinear Difference-Delay Equations with Continuous Time
Directory of Open Access Journals (Sweden)
Michael Gil'
2007-01-01
Full Text Available We consider semilinear difference-delay equations with continuous time in a Euclidean space. Estimates are found for the solutions. Such estimates are then applied to obtain the stability and boundedness criteria for solutions.
Nojiri, S; Nojiri, Shin'ichi; Odintsov, Sergei D.
2005-01-01
The unifying approach to early-time and late-time universe based on phantom cosmology is proposed. We consider gravity-scalar system which contains usual potential and scalar coupling function in front of kinetic term. As a result, the possibility of phantom-non-phantom transition appears in such a way that universe could have effectively phantom equation of state at early time as well as at late time. In fact, the oscillating universe may have several phantom and non-phantom phases. As a second model we suggest generalized holographic dark energy where infrared cutoff is identified with combination of FRW parameters: Hubble constant, particle and future horizons, cosmological constant and universe life-time (if finite). Depending on the specific choice of the model the number of interesting effects occur: the possibility to solve the coincidence problem, crossing of phantom divide and unification of early-time inflationary and late-time accelerating phantom universe. The bound for holographic entropy which d...
Global in time solutions to Kolmogorov-Feller pseudodifferential equations with small parameter
Albeverio, S.; Danilov, V. G.
2011-03-01
The goal in this paper is to demonstrate a new method for constructing globalin-time approximate (asymptotic) solutions of (pseudodifferential) parabolic equations with a small parameter. We show that, in the leading term, such a solution can be constructed by using characteristics, more precisely, by using solutions of the corresponding Hamiltonian system and without using any integral representation. For completeness, we also briefly describe the well-known scheme developed by V. P. Maslov for constructing global-in-time solutions.
Solution of Moving Boundary Space-Time Fractional Burger’s Equation
Directory of Open Access Journals (Sweden)
E. A.-B. Abdel-Salam
2014-01-01
Full Text Available The fractional Riccati expansion method is used to solve fractional differential equations with variable coefficients. To illustrate the effectiveness of the method, the moving boundary space-time fractional Burger’s equation is studied. The obtained solutions include generalized trigonometric and hyperbolic function solutions. Among these solutions, some are found for the first time. The linear and periodic moving boundaries for the kink solution of the Burger’s equation are presented graphically and discussed.
Online Learning Solutions for Freeway Travel Time Prediction
Van Lint, J.W.C.
2008-01-01
Providing travel time information to travelers on available route alternatives in traffic networks is widely believed to yield positive effects on individual drive behavior and (route/departure time) choice behavior, as well as on collective traffic operations in terms of, for example, overall time
Online Learning Solutions for Freeway Travel Time Prediction
Van Lint, J.W.C.
2008-01-01
Providing travel time information to travelers on available route alternatives in traffic networks is widely believed to yield positive effects on individual drive behavior and (route/departure time) choice behavior, as well as on collective traffic operations in terms of, for example, overall time
Larger miliolids of the Late Cretaceous and Paleogene seen through space and time
Directory of Open Access Journals (Sweden)
Vlasta Ćosović
2002-12-01
Full Text Available Spatial and temporal occurrences of the larger (complex miliolids are discussed to give more light on biostratigraphy and paleobiogeographic provinces distribution. Seven generaand 47 species from the Late Cretaceous to Oligocene inhabited shallow marine settings in the Indo-Pacific, Tethyan and Caribbean regions. Of all genera only four (Idalina, Periloculina, Pseudolacazina, Lacazina widespread throughout Tethys in theLate Cretaceous and Paleogene. Single occurrence of Lacazina was recorded further to east (Moluccas. By now the Late Cretaceous genus Adrahentina is known only from the Spain. The newcomer’s Eocene genera were Fabularia and Lacazinella. Fabularia reachedhigh diversity in species term in the Central and Western Tethys and occured as unique genus in Caribbean realm, too. Conversely, during the same period, Lacazinella spread over the southern border of Neo-Tethys reaching New Guinea.On the Adriatic – Dinaric Carbonate Platform, larger miliolids occurred from the Late Cretaceous to Cuisian, having the same biostratigraphically trends and distribution as contemporaneous larger miliolids from the Tethys.
Time to diagnosis in young-onset dementia as compared with late-onset dementia
Vliet, D. van; Vugt, M.E. de; Bakker, C.; Pijnenburg, Y.A.; Vernooij-Dassen, M.J.F.J.; Koopmans, R.T.C.M.; Verhey, F.R.J.
2013-01-01
BACKGROUND: The extent to which specific factors influence diagnostic delays in dementia is unclear. Therefore, the aim of the present study was to compare duration from symptom onset to diagnosis for young-onset dementia (YOD) and late-onset dementia (LOD) and to assess the effect of age at onset,
Two Catacombs of Late Sarmatian Time From Pashkovsky Burial Mound no. 2
Directory of Open Access Journals (Sweden)
Limberis Natalya Yuryevna
2015-12-01
Full Text Available The article deals with two burials from the Kuban basin region excavated in Pashkovsky burial mound no. 2 belonging to Maeotian Pashkovskoe ancient settlement. The burials were made in catacombs of similar construction and orientation. The narrow grave entrances and grave chambers are situated in-line. The grave chambers of the catacombs adjoin one other that probably was the reason for plunder of a little earlier burial no. 2. There were the complete horse skeleton, the cow skull and the sheep chap in the grave entrance ofthe catacomb no. 2. A skeleton of a man (about 50 years old was in extended supine position diagonally across the grave chamber, his scull had SSW orientation. Grave goods found near the buried man include the gray-clay bowl and the mug-jar, the iron spearhead, the long sword and the dagger, the bit with wheel-shaped cheek-pieces, the sickle, the knives and the shoe buckles, the glass bead, the chalk rock bead, the bronze buckle and fibula. The catacomb no. 2 plundered in ancient times situated north-ward of the first one, the southern border of the grave chamber is partially cutted by catacomb no. 1. In the grave entrance of the catacomb no. 1 there were the remains of the horse skeleton and the sheep skull. Grave goods scattered in grave chamber included the gray-clay bowl, pieces of chalk, the bronze ring, fragments of the iron buckle, rod, hasp, silver temple ring, bronze escutcheon for the box lock, the iron snap-up loop and fragments of silver flacon with a cover. Late Sarmatian burial rites and grave goods give evidence of the belonging these burials to spokesmen of the equestrian order. The chronological range of the burials stays within terms from the second half of 2nd to the middle of 3rd century A.D. The lower date of the catacomb no. 1 turns toward the end of the 2nd century A.D., the upper date is limited by the first half of the 3rd century A.D. The catacomb no. 2 is stratigraphically older. The eques status of
The unification of the inflation with late-time acceleration in Born-Infeld- f( R) gravity
Makarenko, Andrey N.
2014-08-01
We study accelerating dynamics from Born-Infeld- f( R) gravity in a simplified conformal approach without matter. In Makarenko et al. (arXiv:1404.2850 [gr-qc], 2011b) it was derived eventually any Dark Energy cosmology from above theory. In this Letter we apply the technique of Makarenko et al. (arXiv:1404.2850 [gr-qc], 2011b) to show that Born-Infeld- f( R) gravity may describe very realistic universe admitting the unification of early-time inflation with late-time acceleration. Specifically, the evolution with periodic as well as non-periodic behavior is considered with possibility to cross the phantom-divide at early or late-times.
Energy Technology Data Exchange (ETDEWEB)
Georg, P.; Georg, D.; Poetter, R.; Doerr, W. [Medical University Vienna/ AKH Wien (Austria). Dept. of Radiooncology; Medical University Vienna (Austria). Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology; Medical University Vienna/ AKH Wien (Austria). Comprehensive Cancer Centre; Boni, A.; Ghabuous, A. [Medical University Vienna/ AKH Wien (Austria). Dept. of Radiooncology; Goldner, G.; Schmid, M.P. [Medical University Vienna/ AKH Wien (Austria). Dept. of Radiooncology; Medical University Vienna/ AKH Wien (Austria). Comprehensive Cancer Centre
2013-07-15
Background and purpose: To analyze the time course of late rectal- and urinary bladder complications after brachytherapy for cervical cancer and to compare the incidence- and prevalence rates thereof. Patients and methods: A total of 225 patients were treated with external-beam radiotherapy (EBRT) and magnetic resonance imaging (MRI)-guided brachytherapy with or without chemotherapy. Late side effects were assessed prospectively using the Late Effects in Normal Tissue - Subjective, Objective, Management and Analytic (LENT/SOMA) scale. The parameters analyzed were time to onset, duration, actuarial incidence- (occurrence of new side effects during a defined time period) and prevalence rates (side effects existing at a defined time point). Results: Median follow-up was 44 months. Side effects (grade 1-4) in rectum and bladder were present in 31 and 49 patients, 14 and 27 months (mean time to onset) after treatment, respectively. All rectal and 76 % of bladder side effects occurred within 3 years after radiotherapy. Mean duration of rectal events was 19 months; 81 % resolved within 3 years of their initial diagnosis. Mean duration of bladder side effects was 20 months; 61 % resolved within 3 years. The 3- and 5-year actuarial complication rates were 16 and 19 % in rectum and 18 and 28 % in bladder, respectively. The corresponding prevalence rates were 9 and 2 % (rectum) and 18 and 21 % (bladder), respectively. Conclusion: Late side effects after cervical cancer radiotherapy are partially reversible, but their time course is organ-dependent. The combined presentation of incidence- and prevalence rates provides the most comprehensive information. (orig.)
Rapid Time Response: A solution for Manufacturing Issue
Directory of Open Access Journals (Sweden)
Norazlin N.
2017-01-01
Full Text Available Respond time in manufacturing give the major impact that able to contribute too many manufacturing issues. Based on two worst case scenario occurred where Toyota in 2009 made a massive vehicles call due to car complexity of 11 major models and over 9 million vehicles. The recalls cost at least $2 billion in cost of repair, lost deals and result in lost 5% of its market share in United State of America, while A380 was reported on missing target in new production and leads to delayed market entry due to their weak product life cycle management (PLM. These cases give a sign to all industries to possess and optimize the facilities for better traceability in shortest time period. In Industry 4.0, the traceability and time respond become the factors for high performance manufacturing and rapid time respond able to expedite the traceability process and strengthen the communication level between man, machine and management. The round trip time (RTT experiment gives variant time respond between two difference operating system for intra and inter-platform signal. If this rapid time respond is adopted in any manufacturing process, the delay in traceability on every issue that lead to losses can be successfully avoided.
Boundary Element Method Solution in the Time Domain For a Moving Time-Dependent Force
DEFF Research Database (Denmark)
Nielsen, Søren R.K.; Kirkegaard, Poul Henning; Rasmussen, K. M.
2001-01-01
satisfy the radiation conditions exactly. In this paper a model based on the BEM is formulated for the solution of the mentioned problem. A numerical solution is obtained for the 2D plane strain case, and comparison is made with the results obtained from a corresponding FEM solution with an impedance...... absorbing boundary condition....
Indian Academy of Sciences (India)
Wenjun Liu; Kewang Chen
2013-09-01
In this paper, we implemented the functional variable method and the modified Riemann–Liouville derivative for the exact solitary wave solutions and periodic wave solutions of the time-fractional Klein–Gordon equation, and the time-fractional Hirota–Satsuma coupled KdV system. This method is extremely simple but effective for handling nonlinear time-fractional differential equations.
Time-periodic solutions of the Einstein’s field equations II:geometric singularities
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In this paper,we construct several kinds of new time-periodic solutions of the vacuum Einstein’s field equations whose Riemann curvature tensors vanish,keep finite or take the infinity at some points in these space-times,respectively.The singularities of these new time-periodic solutions are investigated and some new physical phenomena are discovered.
Jaillard, Etienne; Ordoñez, Martha; Berrones, Gerardo; Bengtson, Peter; Bonhomme, Michel; Jimenez, Nelson; Zambrano, Italo
1996-03-01
) They are eroded by an angular unconformity and capped by early Miocene volcanics and sediments, which express an early Miocene deformation phase. The apparent sedimentary hiatus including most of Eocene-Oligocene times is interpreted as a result of the late Paleocene and late Eocene Incaic tectonic phases.
Target Recognition Using Late-Time Returns from Ultra-Wideband, Short-Pulse Radar
2004-06-01
WIDEBAND, SHORT-PULSE RADAR DISSERTATION Kenneth J. Pascoe, B.S.E.E., M.S. Major, USAF Approved: Dr. Michael J. Havrilla Dissertation Advisor Date Dr...Acknowledgments Thanks to all the people who helped to make this research happen. Thanks to my committee: Dr. Michael Havrilla , the late Major Bill Wood...Singularity Expansion Method 16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON Michael J. Havrilla , Ph.D. (ENG) a. REPORT U b
Odintsov, S D
2016-01-01
We present some cosmological models which unify the late and early-time acceleration eras with the radiation and the matter domination era, and we realize the cosmological models by using the theoretical framework of $F(R)$ gravity. Particularly, the first model unifies the late and early-time acceleration with the matter domination era, and the second model unifies all the evolution eras of our Universe. The two models are described in the same way at early and late times, and only the intermediate stages of the evolution have some differences. Each cosmological model contains two Type IV singularities which are chosen to occur one at the end of the inflationary era and one at the end of the matter domination era. The cosmological models at early times are approximately identical to the $R^2$ inflation model, so these describe a slow-roll inflationary era which ends when the slow-roll parameters become of order one. The inflationary era is followed by the radiation era and after that the matter domination er...
Energy Technology Data Exchange (ETDEWEB)
Belmonte-Beitia, Juan [Departamento de Matematicas, E.T.S. de Ingenieros Industriales and Instituto de Matematica Aplicada a la Ciencia y la Ingenieria (IMACI), Avda. Camilo Jose Cela 3, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain)], E-mail: juan.belmonte@uclm.es; Calvo, Gabriel F. [Departamento de Matematicas, E.T.S. de Ingenieros Industriales and Instituto de Matematica Aplicada a la Ciencia y la Ingenieria (IMACI), Avda. Camilo Jose Cela 3, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain)], E-mail: gabriel.fernandez@uclm.es
2009-01-19
In this Letter, by means of similarity transformations, we construct explicit solutions to the quintic nonlinear Schroedinger equation with potentials and nonlinearities depending both on time and on the spatial coordinates. We present the general approach and use it to study some examples and find nontrivial explicit solutions such as periodic (breathers), quasiperiodic and bright and dark soliton solutions.
Local time-decay of solutions to Schroedinger equations with time-periodic potentials
Galtbayar, A; Yajima, K
2002-01-01
Let $H(t)=-\\Delta+V(t,x)$ be a time-dependent Schr\\"{o}dinger operator on $L^2(\\R^3)$. We assume that $V(t,x)$ is $2\\pi$--periodic in time and decays sufficiently rapidly in space. Let $U(t,0)$ be the associated propagator. For $u_0$ belonging to the continuous spectral subspace of $L^2(\\R^3)$ for the Floquet operator $U(2\\pi, 0)$, we study the behavior of $U(t,0)u_0$ as $t\\to\\infty$ in the topology of $x$-weighted spaces, in the form of asymptotic expansions. Generically the leading term is $t^{-3/2}B_1u_0$. Here $B_1$ is a finite rank operator mapping functions of $x$ to functions of $t$ and $x$, periodic in $t$. If $n\\in\\Z$ is an eigenvalue, or a threshold resonance of the corresponding Floquet Hamiltonian $-i\\pa_t + H(t)$, the leading behavior is $t^{-1/2}B_0u_0$. The point spectral subspace for $U(2\\pi, 0)$ is finite dimensional. If $U(2\\pi, 0)\\phi_j = e^{-i2\\pi\\l_j }\\phi_j$, then $U(t, 0)\\phi_j$ represents a quasi-periodic solution.
Determination of late-time Gamma-Ray (60Co) sensitivity of single diffusion Lot 2N2222A transistors.
Energy Technology Data Exchange (ETDEWEB)
DePriest, Kendall Russell; Kajder, Karen C.; Peters, Curtis D. (American Staff Augmentation Providers, LLC, Albuquerque, NM)
2008-08-01
Sandia National Laboratories (SNL) has embarked on a program to develop a methodology to use damage relations techniques (alternative experimental facilities, modeling, and simulation) to understand the time-dependent effects in transistors (and integrated circuits) caused by neutron irradiations in the Sandia Pulse Reactor-III (SPR-III) facility. The development of these damage equivalence techniques is necessary since SPR-III was shutdown in late 2006. As part of this effort, the late time {gamma}-ray sensitivity of a single diffusion lot of 2N2222A transistors has been characterized using one of the {sup 60}Co irradiation cells at the SNL Gamma Irradiation Facility (GIF). This report summarizes the results of the experiments performed at the GIF.
De Vleeschouwer, David; Da Silva, Anne-Christine; Day, James E.; Whalen, Michael; Claeys, Philippe
2016-04-01
Milankovitch cycles (obliquity, eccentricity and precession) result in changes in the distribution of solar energy over seasons, as well as over latitudes, on time scales of ten thousands of years to millions of years. These changing patterns in insolation have induced significant variations in Earth's past climate over the last 4.5 billion years. Cyclostratigraphy and astrochronology utilize the geologic imprint of such quasi-cyclic climatic variations to measure geologic time. In recent years, major improvements of the Geologic Time Scale have been proposed through the application of cyclostratigraphy, mostly for the Mesozoic and Cenozoic (Gradstein et al., 2012). However, the field of Paleozoic cyclostratigraphy and astrochronology is still in its infancy and the application of cyclostratigraphic techniques in the Paleozoic allows for a whole new range of research questions. For example, unraveling the timing and pacing of environmental changes over the Late Devonian mass extinction on a 105-year time-scale concerns such a novel research question. Here, we present a global cyclostratigraphic framework for late Frasnian to early Famennian climatic and environmental change, through the integration of globally distributed sections. The backbone of this relative time scale consists of previously published cyclostratigraphies for western Canada and Poland (De Vleeschouwer et al., 2012; De Vleeschouwer et al., 2013). We elaborate this Euramerican base by integrating new proxy data -interpreted in terms of astronomical climate forcing- from the Iowa basin (USA, magnetic susceptibility and carbon isotope data) and Belgium (XRF and carbon isotope data). Next, we expand this well-established cyclostratigraphic framework towards the Paleo-Tethys Ocean, using magnetic susceptibility and carbon isotope records from the Fuhe section in South China (Whalen et al., 2015). The resulting global cyclostratigraphic framework implies an important refinement of the late Frasnian to
Directory of Open Access Journals (Sweden)
Emad A.-B. Abdel-Salam
2013-01-01
Full Text Available The fractional Riccati expansion method is proposed to solve fractional differential equations. To illustrate the effectiveness of the method, space-time fractional Korteweg-de Vries equation, regularized long-wave equation, Boussinesq equation, and Klein-Gordon equation are considered. As a result, abundant types of exact analytical solutions are obtained. These solutions include generalized trigonometric and hyperbolic functions solutions which may be useful for further understanding of the mechanisms of the complicated nonlinear physical phenomena and fractional differential equations. Among these solutions, some are found for the first time. The periodic and kink solutions are founded as special case.
Classical and quantum time dependent solutions in string theory
Mart'inez-Prieto, C; Socorro, J
2004-01-01
Using the ontological interpretation of quantum mechanics in a particular sense, we obtain the classical behaviour of the scale factor and two scalar fields, derived from a string effective action for the FRW time dependent model. Besides, the Wheeler-DeWitt equation is solved exactly. We speculate that the same procedure could also be applied to S-branes.
New Quantum Effect: Emission of Cosmic X- or γ-rays by Moving Unstable Particles at Late Times
Urbanowski, K.
2016-11-01
A quantum effect induced by the late time properties of decaying states is discussed and its possible observational consequences are analyzed. It is shown that charged unstable particles as well as neutral unstable particles with non-zero magnetic moment which were able to survive sufficiently long may emit electromagnetic radiation. The nonclassical behavior of unstable particles at late times when deviations of the decay law from the exponential form begin to dominate is a source of the mechanism responsible for this effect. Analyzing the transition times region between exponential and non-exponential form of the survival amplitude it is found that at this time region the instantaneous energy of the unstable particle can take very large values, much larger than the energy of this state at times from the exponential time region. Results obtained for the model considered suggest that this new purely quantum mechanical effect may be responsible for causing unstable particles produced by astrophysical sources and moving with relativistic velocities to emit electromagnetic-, X- or γ-rays at some time intervals from the transition time regions.
Quantum Solution to the Arrow-of-Time Dilemma
Maccone, Lorenzo
2009-08-01
The arrow-of-time dilemma states that the laws of physics are invariant for time inversion, whereas the familiar phenomena we see everyday are not (i.e., entropy increases). I show that, within a quantum mechanical framework, all phenomena which leave a trail of information behind (and hence can be studied by physics) are those where entropy necessarily increases or remains constant. All phenomena where the entropy decreases must not leave any information of their having happened. This situation is completely indistinguishable from their not having happened at all. In the light of this observation, the second law of thermodynamics is reduced to a mere tautology: physics cannot study those processes where entropy has decreased, even if they were commonplace.
Ram, Nilam; Gerstorf, Denis; Fauth, Elizabeth; Zarit, Steven; Malmberg, Bo
2010-01-01
Time is a vehicle that can be used to represent aging-related processes and to index the amount of aging-related resources or burdens individuals have accumulated. Using data on cognitive (memory) performance from two Swedish studies of the elderly (OCTO and OCTO-TWIN), we illustrate how time-as-process and time-as-resources/burdens time metrics can be articulated and incorporated within a growth curve modeling framework. Our results highlight the possibilities for representing the contributions of primary, secondary, and tertiary aspects of aging to late-life changes in cognitive and other domains of functioning.
Pattern and timing of late Cenozoic rapid exhumation and uplift of the Helan Mountain,China
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The Helan Mountain, an intraplate deformation belt in the North China Craton, is located in the northern portion of the China North-South seismic belt, and at the northwestern margin of the Ordos Block. The Cenozoic deformation history of the Helan Mountain is characterized by extension along the eastern Helan Mountain fault (EHSF), resulting in the exhumation and uplift of the Helan Mountain, relative to the rifting of the adjacent Yinchuan Basin. Here we present new apatite fission track (AFT) data from several transects adjacent to the EHSF in the central and northern Helan Mountain. AFT ages from the northern Helan Mountain (Dawukou and Zhengyiguan transects) range from 10 Ma to 89 Ma, whereas AFT ages from the southern Helan Mountain (Suyukou transect) are greater than 71 Ma. The AFT data analysis reveals initiation of rapid uplift and exhumation of the Helan Mountain at 10–12 Ma. Additionally, a plot of the AFT ages versus their mean track length shows a distinctive "boomerang" pattern indicating that the Helan Mountain experienced a discrete phase of accelerated exhumation beginning at 10-12 Ma. Spatially, AFT samples systematically increase in age away from the EHSF and are consistent with late Cenozoic exhumation that was slow in the southwestern Helan Mountain and rapid in the northeastern Helan Mountain, as well more rapid adjacent to the EHSF and slower away from the EHSF. Obviously, the spatial distribution of late Cenozoic exhumation indicates that normal faulting of the EHSF is related to southwestward tilting and rapid exhumation of the Helan Mountain beginning at 10–12 Ma. The uplift and exhumation of the Helan Mountain was a response to the intensive extension of the northwestern margin of the Ordos Block in the late Cenozoic; this occurred under a regional extensional stress field oriented NW-SE along the Yinchuan-Jilantai-Hetao and the Weihe-Shanxi graben systems adjacent to the Ordos Block.
Approximate solutions to infinite dimensional LQ problems over infinite time horizon
Institute of Scientific and Technical Information of China (English)
PAN; Liping; ZHANG; Xu; CHEN; Qihong
2006-01-01
This paper is addressed to develop an approximate method to solve a class of infinite dimensional LQ optimal regulator problems over infinite time horizon. Our algorithm is based on a construction of approximate solutions which solve some finite dimensional LQ optimal regulator problems over finite time horizon, and it is shown that these approximate solutions converge strongly to the desired solution in the double limit sense.
Exact solutions of the (3+1)-dimensional space-time fractional Jimbo-Miwa equation
Aksoy, Esin; Guner, Ozkan; Bekir, Ahmet; Cevikel, Adem C.
2016-06-01
Exact solutions of the (3+1)-dimensional space-time fractional Jimbo-Miwa equation are studied by the generalized Kudryashov method, the exp-function method and the (G'/G)-expansion method. The solutions obtained include the form of hyperbolic functions, trigonometric and rational functions. These methods are effective, simple, and many types of solutions can be obtained at the same time.
Sesma, L Toledo; Loaiza, O
2015-01-01
In this work we construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. This approach is applied to anisotropic cosmological Bianchi type I model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Under this approach, we present an isotropization mechanism for the Bianchi I cosmological model through the analysis of the ratio between the anisotropic parameters and the volume of the Universe which in general keeps constant or runs into zero for late times. Finally, we present some solutions to the corresponding Wheeler-DeWitt (WDW) equation in the context of Standard Quantum Cosmology.
Exact Solution to the One-Dimensional Dirac Equation with Time Varying Mass
Institute of Scientific and Technical Information of China (English)
YANG Jin; XIANG An-Ping; YU Wan-Lun
2003-01-01
We directly use the quantum-invariant operator method to obtain the closed-form solution to the one-dimensional Dirac equation with a time-changing mass with a little manipulation. The solution got is also applicable forthe case with time-independence mass.
Exact Solution to the One-Dimensional Dirac Equation with Time Varying Mass
Institute of Scientific and Technical Information of China (English)
YANGJin; XIANGAn-Ping; YUWan-Lun
2003-01-01
We directly use the quantum-invariant operator method to obtain the closed-form solution to the one-dimensional Dirac equation with a time-changing mass with a little manipulation. The solution got is also applicable for the case with time-independence mass.
Time-dependent solutions of the spatially implicit neutral model of biodiversity.
Chisholm, Ryan A
2011-09-01
Previous research into the neutral theory of biodiversity has focused mainly on equilibrium solutions rather than time-dependent solutions. Understanding the time-dependent solutions is essential for applying neutral theory to ecosystems in which time-dependent processes, such as succession and invasion, are driving the dynamics. Time-dependent solutions also facilitate tests against data that are stronger than those based on static equilibrium patterns. Here I investigate the time-dependent solutions of the classic spatially implicit neutral model, in which a small local community is coupled to a much larger metacommunity through immigration. I present explicit general formulas for the eigenvalues, left eigenvectors and right eigenvectors of the models's transition matrix. The time-dependent solutions can then be expressed in terms of these eigenvalues and eigenvectors. Some of these results are translated directly from existing results for the classic Moran model of population genetics (the Moran model is equivalent to the spatially implicit neutral model after a reparameterization); others of the results are new. I demonstrate that the asymptotic time-dependent solution corresponding to just these first two eigenvectors can be a good approximation to the full time-dependent solution. I also demonstrate the feasibility of a partial eigendecomposition of the transition matrix, which facilitates direct application of the results to a biologically relevant example in which a newly invading species is initially present in the metacommunity but absent from the local community.
Directory of Open Access Journals (Sweden)
Mridula Garg
2011-12-01
Full Text Available In the present paper, we use generalized differential transform method (GDTM to derive solutions of some linear and nonlinear space-time fractional Fokker–Planck equations (FPE in closed form. The space and time fractional derivatives are considered in Caputo sense and the solutions are obtained in terms of Mittag-Leffler functions.
Magnetic Cycles and Rotation Periods of Late Type Stars from photometric time series
Mascareño, A Suárez; Hernández, J I González
2016-01-01
We investigate the photometric modulation induced by magnetic activity cycles and study the relationship between rotation period and activity cycle(s) in late-type (FGKM) stars. We analyse light-curves spanning up to 9 years of 125 nearby stars provided by the ASAS survey. The sample is mainly conformed by low-activity main sequence late A to mid M-type stars. A search is performed for short (days) and long-term (years) periodic variations in the photometry. We modelled with combinations of sinusoids the light-curves to measure the properties of these periodic signals. To provide a better statistical interpretation of our results we complement them with the results from previous similar works. We have been able to measure long-term photometric cycles of 47 stars. Rotational modulation was also detected and rotational periods measured in 36 stars. For 28 stars we have simultaneous measurements of both, activity cycles and rotational periods, being 17 of them M-type stars. From sinusoidal fits we measured both ...
Time consistent Pareto solutions in common access resource gameswith asymmetric players
De-Paz, Albert; Marín Solano, Jesús; Navas, Jorge
2011-01-01
In the analysis of equilibrium policies in a di erential game, if agents have different time preference rates, the cooperative (Pareto optimum) solution obtained by applying the Pontryagin's Maximum Principle becomes time inconsistent. In this work we derive a set of dynamic programming equations (in discrete and continuous time) whose solutions are time consistent equilibrium rules for N-player cooperative di erential games in which agents di er in their instantaneous utility functions and a...
LARGE-TIME BEHAVIOR OF SOLUTIONS OF QUANTUM HYDRODYNAMIC MODEL FOR SEMICONDUCTORS
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A one-dimensional quantum hydrodynamic model (or quantum Euler-Poisson system) for semiconductors with initial boundary conditions is considered for general pressure-density function. The existence and uniqueness of the classical solution of the corresponding steady-state quantum hydrodynamic equations is proved. Furthermore, the global existence of classical solution, when the initial datum is a perturbation of the steadystate solution, is obtained. This solution tends to the corresponding steady-state solution exponentially fast as the time tends to infinity.
Advanced in Visualization of 3D Time-Dependent CFD Solutions
Lane, David A.; Lasinski, T. A. (Technical Monitor)
1995-01-01
Numerical simulations of complex 3D time-dependent (unsteady) flows are becoming increasingly feasible because of the progress in computing systems. Unfortunately, many existing flow visualization systems were developed for time-independent (steady) solutions and do not adequately depict solutions from unsteady flow simulations. Furthermore, most systems only handle one time step of the solutions individually and do not consider the time-dependent nature of the solutions. For example, instantaneous streamlines are computed by tracking the particles using one time step of the solution. However, for streaklines and timelines, particles need to be tracked through all time steps. Streaklines can reveal quite different information about the flow than those revealed by instantaneous streamlines. Comparisons of instantaneous streamlines with dynamic streaklines are shown. For a complex 3D flow simulation, it is common to generate a grid system with several millions of grid points and to have tens of thousands of time steps. The disk requirement for storing the flow data can easily be tens of gigabytes. Visualizing solutions of this magnitude is a challenging problem with today's computer hardware technology. Even interactive visualization of one time step of the flow data can be a problem for some existing flow visualization systems because of the size of the grid. Current approaches for visualizing complex 3D time-dependent CFD solutions are described. The flow visualization system developed at NASA Ames Research Center to compute time-dependent particle traces from unsteady CFD solutions is described. The system computes particle traces (streaklines) by integrating through the time steps. This system has been used by several NASA scientists to visualize their CFD time-dependent solutions. The flow visualization capabilities of this system are described, and visualization results are shown.
Patton, H. J.; Larmat, C. S.; Rougier, E.
2016-12-01
Seismic moments for chemical shots making up Phase I of the Source Physics Experiments (SPE) are estimated from 6 Hz Rg waves under the assumption that the shots are pure explosions. These apparent explosion moments are compared to moments determined using the Reduced Displacement Potential (RDP) method applied to free field data. LIDAR/photogrammetry observations, strong ground motions on the free surface near ground zero, and moment tensor inversion results are evidence in support of the fourth shot SPE-4P being essentially a pure explosion. The apparent moment for SPE-4P is 9 × 1010 Nm in good agreement with the RDP moment 8 × 1010 Nm. In stark contrast, apparent moments for the first three shots are three to four times smaller than RDP moments. Data show that spallation occurred on these shots, as well as permanent deformations detected with ground-based LIDAR. As such, the source medium suffered late-time damage. The late-time damage source model predicts destructive interference between Rg waves radiated by explosion and damage sources, which reduces amplitudes and explains why apparent moments are smaller than RDP moments based on compressional energy emitted directly from the source. SPE-5 was conducted at roughly the same yield-scaled burial depth as SPE-2 and -3, but with five times the yield. As such, the damage source model predicts less reduction of apparent moment. At this writing, preliminary results from Rg interferometry and RDP moments confirm this prediction. SPE-6 is scheduled for the fall of 2016, and it should have the strongest damage source of all SPE shots. The damage model predicts that the polarity of Rg waves could be reversed. Realization of this prediction will be strong confirmation of the late-time damage source model. This abstract has a Los Alamos National Laboratory Unlimited Release Number LA-UR-16-25709.
Late cretaceous precessional cycles in double time: a warm-Earth milankovitch response.
Park, J; D'Hondt, S L; King, J W; Gibson, C
1993-09-10
Late Cretaceous climatic cycles are reflected in lithological and magnetic variations in carbonate sediments from South Atlantic Deep-Sea Drilling Project site 516F at a paleolatitude of roughly 30 degrees S. Magnetic susceptibility cycles 20 to 60 centimeters in length appear to be controlled by the precession of the equinoxes. Cyclicity is particularly robust within a 24-meter interval in the lower Campanian, where overtone spectral peaks are observed as well as secondary susceptibility maxima within individual precession cycles. One model for this behavior is that sedimentation in the narrow Cretaceous South Atlantic was controlled by equatorial climate dynamics, with the precessional insolation signal rectified by the large land masses surrounding the ocean basin.
Abdel-Salam, Emad A-B; Hassan, Gmal F
2015-01-01
In this paper, the fractional projective Riccati expansion method is proposed to solve fractional differential equations. To illustrate the effectiveness of the method, we discuss the space-time fractional Burgers equation, the space-time fractional mKdV equation and time fractional biological population model. The solutions are expressed in terms of fractional hyperbolic functions. These solutions are useful to understand the mechanisms of the complicated nonlinear physical phenomena and fractional differential equations. Among these solutions, some are found for the first time. The fractal index for the obtained results is equal to one. Counter examples to compute the fractal index are introduced in appendix.
The Evolutionary Algorithm to Find Robust Pareto-Optimal Solutions over Time
Directory of Open Access Journals (Sweden)
Meirong Chen
2015-01-01
Full Text Available In dynamic multiobjective optimization problems, the environmental parameters change over time, which makes the true pareto fronts shifted. So far, most works of research on dynamic multiobjective optimization methods have concentrated on detecting the changed environment and triggering the population based optimization methods so as to track the moving pareto fronts over time. Yet, in many real-world applications, it is not necessary to find the optimal nondominant solutions in each dynamic environment. To solve this weakness, a novel method called robust pareto-optimal solution over time is proposed. It is in fact to replace the optimal pareto front at each time-varying moment with the series of robust pareto-optimal solutions. This means that each robust solution can fit for more than one time-varying moment. Two metrics, including the average survival time and average robust generational distance, are present to measure the robustness of the robust pareto solution set. Another contribution is to construct the algorithm framework searching for robust pareto-optimal solutions over time based on the survival time. Experimental results indicate that this definition is a more practical and time-saving method of addressing dynamic multiobjective optimization problems changing over time.
Institute of Scientific and Technical Information of China (English)
Li Hua-Mei
2005-01-01
By using the mapping method and an appropriate transformation, we find new exact solutions of nonlinear Gross-Pitaevskii equation with weak bias magnetic and time-dependent laser fields. The solutions obtained in this paper include Jacobian elliptic function solutions, combined Jacobian elliptic function solutions , triangular function solutions, bright and dark solitons, and soliton-like solutions.
An infinite branching hierarchy of time-periodic solutions of the Benjamin-Ono equation
Energy Technology Data Exchange (ETDEWEB)
Wilkening, Jon
2008-07-01
We present a new representation of solutions of the Benjamin-Ono equation that are periodic in space and time. Up to an additive constant and a Galilean transformation, each of these solutions is a previously known, multi-periodic solution; however, the new representation unifies the subset of such solutions with a fixed spatial period and a continuously varying temporal period into a single network of smooth manifolds connected together by an infinite hierarchy of bifurcations. Our representation explicitly describes the evolution of the Fourier modes of the solution as well as the particle trajectories in a meromorphic representation of these solutions; therefore, we have also solved the problem of finding periodic solutions of the ordinary differential equation governing these particles, including a description of a bifurcation mechanism for adding or removing particles without destroying periodicity. We illustrate the types of bifurcation that occur with several examples, including degenerate bifurcations not predicted by linearization about traveling waves.
Late-time Light Curves of Type II Supernovae: Physical Properties of SNe and Their Environment
Otsuka, Masaaki; Panagia, Nino; Fabbri, Joanna; Barlow, Michael J; Clayton, Geoffrey C; Gallagher, Joseph S; Sugerman, Ben E K; Wesson, Roger; Andrews, Jennifer E; Ercolano, Barbara; Welch, Douglas
2011-01-01
We present BVRIJHK band photometry of 6 core-collapse supernovae, SNe 1999bw, 2002hh, 2003gd, 2004et, 2005cs, and 2006bc measured at late epochs (>2 yrs) based on Hubble Space Telescope (HST), Gemini north, and WIYN telescopes. We also show the JHK lightcurves of a supernova impostor SN 2008S up to day 575. Of our 43 HST observations in total, 36 observations are successful in detecting the light from the SNe alone and measuring magnitudes of all the targets. HST observations show a resolved scattered light echo around SN 2003gd at day 1520 and around SN 2002hh at day 1717. Our Gemini and WIYN observations detected SNe 2002hh and 2004et, as well. Combining our data with previously published data, we show VRIJHK-band lightcurves and estimate decline magnitude rates at each band in 4 different phases. Our prior work on these lightcurves and other data indicate that dust is forming in our targets from day ~300-400, supporting SN dust formation theory. In this paper we focus on other physical properties derived f...
SN 2009ip at late times - an interacting transient at +2 years
Fraser, Morgan; Pastorello, Andrea; Jerkstrand, Anders; Smartt, Stephen J; Chen, Ting-Wan; Childress, Michael; Gilmore, Gerard; Inserra, Cosimo; Kankare, Erkki; Margheim, Steve; Mattila, Seppo; Valenti, Stefano; Ashall, Christopher; Benetti, Stefano; Botticella, Maria Teresa; Bauer, Franz Erik; Campbell, Heather; Elias-Rosa, Nancy; Fleury, Mathilde; Gal-Yam, Avishay; Hachinger, Stephan; Howell, D Andrew; Guillou, Laurent Le; Léget, Pierre-François; Morales-Garoffolo, Antonia; Polshaw, Joe; Spiro, Susanna; Sullivan, Mark; Taubenberger, Stefan; Turatto, Massimo; Walker, Emma S; Young, David R; Zhang, Bonnie
2015-01-01
We present photometric and spectroscopic observations of the interacting transient SN 2009ip taken during the 2013 and 2014 observing seasons. We characterise the photometric evolution as a steady and smooth decline in all bands, with a decline rate that is slower than expected for a solely $^{56}$Co-powered supernova at late phases. No further outbursts or eruptions were seen over a two year period from 2012 December until 2014 December. SN 2009ip remains brighter than its historic minimum from pre-discovery images. Spectroscopically, SN 2009ip continues to be dominated by strong, narrow ($\\lesssim$2000 km~s$^{-1}$) emission lines of H, He, Ca, and Fe. While we make tenuous detections of [Fe~{\\sc ii}] $\\lambda$7155 and [O~{\\sc i}] $\\lambda\\lambda$6300,6364 lines at the end of 2013 June and the start of 2013 October respectively, we see no strong broad nebular emission lines that could point to a core-collapse origin. In general, the lines appear relatively symmetric, with the exception of our final spectrum ...
Short-time existence of solutions for mean-field games with congestion
Gomes, Diogo A.
2015-11-20
We consider time-dependent mean-field games with congestion that are given by a Hamilton–Jacobi equation coupled with a Fokker–Planck equation. These models are motivated by crowd dynamics in which agents have difficulty moving in high-density areas. The congestion effects make the Hamilton–Jacobi equation singular. The uniqueness of solutions for this problem is well understood; however, the existence of classical solutions was only known in very special cases, stationary problems with quadratic Hamiltonians and some time-dependent explicit examples. Here, we demonstrate the short-time existence of C∞ solutions for sub-quadratic Hamiltonians.
Stokes, Peter W; Read, Wayne; White, Ronald D
2014-01-01
The solution of a Caputo time fractional diffusion equation of order $0<\\alpha<1$ is found in terms of the solution of a corresponding integer order diffusion equation. We demonstrate a linear time mapping between these solutions that allows for accelerated computation of the solution of the fractional order problem. In the context of an $N$-point finite difference time discretisation, the mapping allows for an improvement in time computational complexity from $O\\left(N^{2}\\right)$ to $O\\left(N^{\\alpha}\\right)$, given a precomputation of $O\\left(N^{1+\\alpha}\\ln N\\right)$. The mapping is applied successfully to the least-squares fitting of a fractional advection diffusion model for the current in a time-of-flight experiment, resulting in a computational speed up in the range of one to three orders of magnitude for realistic problem sizes.
Energy Technology Data Exchange (ETDEWEB)
Yan, Lin; Masci, F. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Quimby, R. [Department of Astronomy, San Diego State University, San Diego, CA 92182 (United States); Ofek, E.; Gal-Yam, A.; Vreeswijk, P. M.; Leloudas, G.; Cia, A. de; Yaron, O. [Department of Particle Physics and Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Mazzali, P. [Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Perley, D. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Cao, Y.; Kulkarni, S. R. [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Nugent, P. E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Rebbapragada, Umaa D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Woźniak, P. R., E-mail: lyan@ipac.caltech.edu [Space and Remote Sensing, ISR-2, MS-B244 Los Alamos National Laboratory Los Alamos, NM 87545 (United States)
2015-12-01
iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z = 0.3434, with a slow-evolving light curve and spectral features similar to SN2007bi. It rises in 83–148 days to reach a peak bolometric luminosity of ∼1.3 × 10{sup 44} erg s{sup −1}, then decays slowly at 0.015 mag day{sup −1}. The measured ejecta velocity is ∼ 13,000 km s{sup −1}. The inferred explosion characteristics, such as the ejecta mass (70–220 M{sub ⊙}), and the total radiative and kinetic energy (E{sub rad} ∼ 10{sup 51} erg, E{sub kin} ∼ 2 × 10{sup 53} erg), are typical of slow-evolving H-poor SLSN events. However, the late-time spectrum taken at +251 days (rest, post-peak) reveals a Balmer Hα emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ∼4500 km s{sup −1} and a ∼300 km s{sup −1} blueward shift relative to the narrow component. We interpret this broad Hα emission with a luminosity of ∼2 × 10{sup 41} erg s{sup −1} as resulting from the interaction between the supernova ejecta and a discrete H-rich shell, located at a distance of ∼4 × 10{sup 16} cm from the explosion site. This interaction causes the rest-frame r-band LC to brighten at late times. The fact that the late-time spectra are not completely absorbed by the shock-ionized H-shell implies that its Thomson scattering optical depth is likely ≤1, thus setting upper limits on the shell mass ≤30 M{sub ⊙}. Of the existing models, a Pulsational Pair Instability supernova model can naturally explain the observed 30 M{sub ⊙} H-shell, ejected from a progenitor star with an initial mass of (95–150) M{sub ⊙} about 40 years ago. We estimate that at least ∼15% of all SLSNe-I may have late-time Balmer emission lines.
Pérez-Torres, M A; Colina, L; Torrelles, J M; Panagia, N; Wilson, A; Kankare, E; Mattila, S
2009-01-01
We present the results of an eight-year long monitoring of the radio emission from the Luminous Infrared Galaxy (LIRG) NGC 7469, using 8.4 GHz Very Large Array (VLA) observations at 0.3'' resolution. Our monitoring shows that the late time evolution of the radio supernova SN 2000ft follows a decline very similar to that displayed at earlier times of its optically thin phase. The late time radio emission of SN 2000ft is therefore still being powered by its interaction with the presupernova stellar wind, and not with the interstellar medium (ISM). Indeed, the ram pressure of the presupernova wind is \\rho_w v_w^2 \\approx 7.6E-9 dyn/cm^2, at a supernova age of approximately 2127 days, which is significantly larger than the expected pressure of the ISM around SN 2000ft. At this age, the SN shock has reached a distance r_{sh \\approx 0.06 pc, and our observations are probing the interaction of the SN with dense material that was ejected by the presupernova star about 5820 years prior to its explosion. From our VLA m...
Late-time photometry of two nearby type Ⅱ-P supernovae: 2004dj and 2004et
Institute of Scientific and Technical Information of China (English)
Tian-Meng Zhang; Xiao-Feng Wang; Xu Zhou; Jun Ma; Zhao-Ji Jiang; Jiang-Hua Wu; Zhen-Yu Wu; Stéphane Basa
2009-01-01
We present late-time photometry for two bright type Ⅱ-P supernovae (SNe) 2004dj and 2004et, extending over 400 d after the explosion, which are measured with a set of intermediate-band filters that have the advantage of tracing the strength variations of some spectral features. Although these two SNe Ⅱ-P exhibit similar photometric evolution at earlier times, they diverge during the nebular phase. SN 2004dj shows a slow late-time decline rate with ～0.7±0.1 mag (100d)-1 during the period ranging from t≈200-300 d after the explosion, while SN 2004et shows a much faster decline rate at a comparable phase, e.g., 1.3±0.1 mag (100d)-1. The steeper decay rate seen in SN 2004et is likely due to dust formation in the explosion ejecta. Based on intermediate-band photometry, we derived the evolution of the feature lines [e.g., Hα] of SNe 2004dj and 2004et which are similar in flux at comparable phases but perhaps with significantly different decay rates. The origin of the observed variations in the continuum and the feature lines is briefly discussed.
The precise time-dependent solution of the Fokker–Planck equation with anomalous diffusion
Energy Technology Data Exchange (ETDEWEB)
Guo, Ran; Du, Jiulin, E-mail: jiulindu@aliyun.com
2015-08-15
We study the time behavior of the Fokker–Planck equation in Zwanzig’s rule (the backward-Ito’s rule) based on the Langevin equation of Brownian motion with an anomalous diffusion in a complex medium. The diffusion coefficient is a function in momentum space and follows a generalized fluctuation–dissipation relation. We obtain the precise time-dependent analytical solution of the Fokker–Planck equation and at long time the solution approaches to a stationary power-law distribution in nonextensive statistics. As a test, numerically we have demonstrated the accuracy and validity of the time-dependent solution. - Highlights: • The precise time-dependent solution of the Fokker–Planck equation with anomalous diffusion is found. • The anomalous diffusion satisfies a generalized fluctuation–dissipation relation. • At long time the time-dependent solution approaches to a power-law distribution in nonextensive statistics. • Numerically we have demonstrated the accuracy and validity of the time-dependent solution.
EXISTENCE OF PERIODIC SOLUTIONS FOR A DISCRETE-TIME MODEL OF TWO-CELL CNNS
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
We investigate a class of discrete-time model of two-cell cellular neural networks with symmetric template. By using the Lyapunov direct method, La-Salle's invariance principle, we discuss the existence and the stability of periodic solutions. The model considered has attractive 2-periodic and unstable 2-periodic solutions.
Effect of solution heat treatment time on a rheocast Al-Zn-Mg-Cu alloy
CSIR Research Space (South Africa)
Mazibuko, NE
2011-06-01
Full Text Available During rheo-high pressure die casting (R-HPDC) of Al-Zn-Mg-Cu alloys a coarse eutectic phase is formed. This eutectic phase is difficult to take into solution because of its size and it would require longer solution heat treatment times...
ASYMPTOTIC BEHAVIOR OF SOLUTIONS TO SECOND ORDER IMPULSIVE DIFFERENTIAL EQUATION ON TIME SCALES
Institute of Scientific and Technical Information of China (English)
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.
On Nonnegative Solutions of Fractional q-Linear Time-Varying Dynamic Systems with Delayed Dynamics
Directory of Open Access Journals (Sweden)
M. De la Sen
2014-01-01
Full Text Available This paper is devoted to the investigation of nonnegative solutions and the stability and asymptotic properties of the solutions of fractional differential dynamic linear time-varying systems involving delayed dynamics with delays. The dynamic systems are described based on q-calculus and Caputo fractional derivatives on any order.
A time dependent solution for the operation of ion chambers in a high ionization background
Velissaris, C
2005-01-01
We have derived a time dependent solution describing the development of space charge inside an ion chamber subjected to an externally caused ionization rate N. The solution enables the derivation of a formula that the operational parameters of the chamber must satisfy for saturation free operation. This formula contains a correction factor to account for the finite duration of the ionization rate N.
Yuan, Rong
2007-06-01
In this paper, we study almost periodic logistic delay differential equations. The existence and module of almost periodic solutions are investigated. In particular, we extend some results of Seifert in [G. Seifert, Almost periodic solutions of certain differential equations with piecewise constant delays and almost periodic time dependence, J. Differential Equations 164 (2000) 451-458].
Sahadevan, R.; Prakash, P.
2017-01-01
We show how invariant subspace method can be extended to time fractional coupled nonlinear partial differential equations and construct their exact solutions. Effectiveness of the method has been illustrated through time fractional Hunter-Saxton equation, time fractional coupled nonlinear diffusion system, time fractional coupled Boussinesq equation and time fractional Whitman-Broer-Kaup system. Also we explain how maximal dimension of the time fractional coupled nonlinear partial differential equations can be estimated.
Modeling solute transport in distribution networks with variable demand and time step sizes.
Energy Technology Data Exchange (ETDEWEB)
Peyton, Chad E.; Bilisoly, Roger Lee; Buchberger, Steven G. (University of Cincinnati, Cincinnati, OH); McKenna, Sean Andrew; Yarrington, Lane
2004-06-01
The effect of variable demands at short time scales on the transport of a solute through a water distribution network has not previously been studied. We simulate flow and transport in a small water distribution network using EPANET to explore the effect of variable demand on solute transport across a range of hydraulic time step scales from 1 minute to 2 hours. We show that variable demands at short time scales can have the following effects: smoothing of a pulse of tracer injected into a distribution network and increasing the variability of both the transport pathway and transport timing through the network. Variable demands are simulated for these different time step sizes using a previously developed Poisson rectangular pulse (PRP) demand generator that considers demand at a node to be a combination of exponentially distributed arrival times with log-normally distributed intensities and durations. Solute is introduced at a tank and at three different network nodes and concentrations are modeled through the system using the Lagrangian transport scheme within EPANET. The transport equations within EPANET assume perfect mixing of the solute within a parcel of water and therefore physical dispersion cannot occur. However, variation in demands along the solute transport path contribute to both removal and distortion of the injected pulse. The model performance measures examined are the distribution of the Reynolds number, the variation in the center of mass of the solute across time, and the transport path and timing of the solute through the network. Variation in all three performance measures is greatest at the shortest time step sizes. As the scale of the time step increases, the variability in these performance measures decreases. The largest time steps produce results that are inconsistent with the results produced by the smaller time steps.
Setting the Time Frame - Investigating Culture-Environment Interactions in the Late Quaternary
Klasen, N.; Just, J.; Rethemeyer, J.
2015-12-01
We present a status update of luminescence age estimates of sediments from Ethiopia and the Iberian Peninsula that are related to human occupation and are currently being investigated in the interdisciplinary Collaborative Research Center "Our way to Europe - Culture-Environment Interaction and Human Mobility in the Late Quaternary" (CRC806). The aim of the project is to investigate the dispersal of anatomically modern humans from Africa to Europe, and a robust chronology is essential. In the CRC806, dating is provided by luminescence, palaeomagnetic and radiocarbon techniques. A key site of the CRC806 is Chew Bahir in Ethiopia. This lake basin is located in the source area of the emergence of anatomically modern humans. Radiocarbon, luminescence and palaeomagnetic dating have been used to develop an age-depth model for drill core sediments that date back to 115 ka over 42 m depth. The model is independent of palaeoclimatic proxy interpretation. On the Iberian Peninsula cave deposits have been dated with luminescence techniques and compared to radiocarbon ages wherever applicable. Recently, existing radiocarbon chronologies on the Iberian Peninsula have been revised in light of methodological developments. Robust luminescence dating is therefore especially important in this region, where the stratigraphy is difficult to constrain. We aim to improve the precision of luminescence age estimates by comparing different measurement techniques for equivalent dose and dose-rate determinations, and by using Bayesian statistics to develop age-depth models. Combining different chronological techniques has enabled the development of accurate and precise chronologies, which will allow a better understanding of the emergence of modern humans.
Frisina, Pasquale G; Sclafani, Anthony
2002-12-01
Opioid antagonists suppress the intake of sweet solutions, but typically have little effect on the initial rate of drinking. The lack of an early drug response was investigated in the present study because it questions the general idea that opioid antagonists reduce the hedonic response to sweets. The first experiment, which measured the rat's licking response to a sucrose+saccharin (S+s) solution, revealed that naltrexone suppressed S+s intake but not initial lick rates. Experiment 2A indicated that the drug's delayed behavioral effect was not due to the 10-min injection-test interval used. Increasing the interval to 20 min did not reduce the latency of drug action. Experiment 2B tested the idea that rats require several minutes to detect that naltrexone has reduced the hedonic value of the S+s solution. The S+s solution was presented either for 30 min without interruption or for 3 min followed, after a 6-min delay, by another 27-min access. In both test conditions, naltrexone did not suppress S+s licking until 7-9 min of drinking had occurred. However, the drug blocked an "appetizer effect"; a post-delay increase in licking rate produced by the split-session test procedure. Microstructure analysis indicated that in all cases, naltrexone reduced S+s licking by reducing the number of lick clusters rather than lick cluster size. In contrast to these drug effects, Experiment 2C showed that reducing the concentration of the S+s solution decreased initial lick rates. Together, these findings suggest that opioid antagonists do not affect all aspects of flavor hedonics, but may primarily alter the intake-maintaining action of palatable flavors.
Existence of the time periodic solution for damped Schroedinger-Boussinesq equation
Institute of Scientific and Technical Information of China (English)
BolingGUO; XianyunDU
2000-01-01
In this paper, we study the time priodic solution for the weakly damped Schroedinger-Boussinesq equation, by Galerkin method, and prove the existence and uniqueness of the equations under some appropriate conditions.
Positive Almost Periodic Solutions for a Time-Varying Fishing Model with Delay
Directory of Open Access Journals (Sweden)
Xia Li
2011-01-01
Full Text Available This paper is concerned with a time-varying fishing model with delay. By means of the continuation theorem of coincidence degree theory, we prove that it has at least one positive almost periodic solution.
Solution of Semi-Boundless Mixed Problem for Time-fractional Telegraph Equation
Institute of Scientific and Technical Information of China (English)
2007-01-01
In this paper, we study the semi-boundless mixed problem for time-fractional telegraph equation. We are able to use the integral transform method (the Fourier sin and cos transforms) to obtain the solution.
Late time cosmic acceleration from vacuum Brans-Dicke theory in 5D
de Leon, J Ponce
2009-01-01
We show that the scalar-vacuum Brans-Dicke equations in 5D are equivalent to Brans-Dicke theory in 4D with a self interacting potential and an effective matter field. The cosmological implication, in the context of FRW models, is that the observed accelerated expansion of the universe comes naturally from the condition that the scalar field is not a ghost, i.e., $\\omega > - 3/2$. We find an effective matter-dominated 4D universe which shows accelerated expansion if $- 3/2 < \\omega < - 1$. We study the question of whether accelerated expansion can be made compatible with large values of $\\omega$, within the framework of a 5D scalar-vacuum Brans-Dicke theory with variable, instead of constant, parameter $\\omega$. In this framework, and based on a general class of solutions of the field equations, we demonstrate that accelerated expansion is incompatible with large values of $\\omega$.
Almost Periodic Solution for Memristive Neural Networks with Time-Varying Delays
Directory of Open Access Journals (Sweden)
Huaiqin Wu
2013-01-01
Full Text Available This paper is concerned with the dynamical stability analysis for almost periodic solution of memristive neural networks with time-varying delays. Under the framework of Filippov solutions, by applying the inequality analysis techniques, the existence and asymptotically almost periodic behavior of solutions are discussed. Based on the differential inclusions theory and Lyapunov functional approach, the stability issues of almost periodic solution are investigated, and a sufficient condition for the existence, uniqueness, and global exponential stability of the almost periodic solution is established. Moreover, as a special case, the condition which ensures the global exponential stability of a unique periodic solution is also presented for the considered memristive neural networks. Two examples are given to illustrate the validity of the theoretical results.
Construction of exact Ermakov-Pinney solutions and time-dependent quantum oscillators
Kim, Sang Pyo; Kim, Won
2016-11-01
The harmonic oscillator with a time-dependent frequency has a family of linear quantum invariants for the time-dependent Schrödinger equation, which are determined by any two independent solutions to the classical equation of motion. Ermakov and Pinney have shown that a general solution to the time-dependent oscillator with an inverse cubic term can be expressed in terms of two independent solutions to the time-dependent oscillator. We explore the connection between linear quantum invariants and the Ermakov-Pinney solution for the time-dependent harmonic oscillator. We advance a novel method to construct Ermakov-Pinney solutions to a class of time-dependent oscillators and the wave functions for the time-dependent Schrödinger equation. We further show that the first and the second Pöschl-Teller potentials belong to a special class of exact time-dependent oscillators. A perturbation method is proposed for any slowly-varying time-dependent frequency.
Directory of Open Access Journals (Sweden)
Birol İbiş
2014-01-01
Full Text Available This paper aims to obtain the approximate solution of time-fractional advection-dispersion equation (FADE involving Jumarie’s modification of Riemann-Liouville derivative by the fractional variational iteration method (FVIM. FVIM provides an analytical approximate solution in the form of a convergent series. Some examples are given and the results indicate that the FVIM is of high accuracy, more efficient, and more convenient for solving time FADEs.
Late-time spectroscopy of SN 2002hh: A continued visible light echo with no shock interaction yet
Andrews, Jennifer E; Mauerhan, Jon C
2015-01-01
Supernova (SN) 2002hh was unusual among core-collapse SNe because it was highly reddened, and displayed a bright infrared (IR) excess due to radiatively heated dust in its circumstellar medium (CSM). Estimates for the mass of dust responsible for the IR echo suggested the presence of a massive shell within 0.26 pc of the star. For a velocity of 5000 - 10000 km/s, this material should be hit by the SN blast wave at late times, starting at roughly 12 years post-explosion. We have obtained deep late-time spectra with the MMT Blue Channel spectrograph to search for any spectral signatures of ongoing shock interaction. Interaction with a strength comparable to SN 1987A's collision with the equatorial ring would be detected in our data. However, in the spectra reported here, we do not detect clear signs of strong CSM interaction, contrary to expectations based on the reported radii of the dust shell. We do, however, detect emission associated with the old SN, and we find that the broad lines in the spectrum indicat...
Late-time spectroscopy of SN 2002hh: a continued visible light echo with no shock interaction yet
Andrews, J. E.; Smith, Nathan; Mauerhan, Jon C.
2015-08-01
Supernova (SN) 2002hh was unusual among core-collapse SNe because it was highly reddened, and displayed a bright infrared (IR) excess due to radiatively heated dust in its circumstellar medium (CSM). Estimates for the mass of dust responsible for the IR echo suggested the presence of a massive shell within 0.26 pc of the star. For a velocity of 5000-10 000 km s-1, this material should be hit by the SN blast wave at late times, starting at roughly 12 years post-explosion. We have obtained deep late-time spectra with the Multiple Mirror Telescope (MMT) Blue Channel spectrograph to search for any spectral signatures of ongoing shock interaction. Interaction with a strength comparable to SN 1987A's collision with the equatorial ring would be detected in our data. However, in the spectra reported here, we do not detect clear signs of strong CSM interaction, contrary to expectations based on the reported radii of the dust shell. We do, however, detect emission associated with the old SN, and we find that the broad lines in the spectrum indicate a continuation of an ongoing reflected light echo, which appears similar to the spectrum at peak luminosity for this Type II-P event.
Searching for swept-up Hydrogen and Helium in the late-time spectra of 11 nearby Type Ia supernovae
Maguire, Kate; Sullivan, Mark; Mazzali, Paolo A
2015-01-01
The direct detection of a stellar system that explodes as a Type Ia supernova (SN Ia) has not yet been successful. Various indirect methods have been used to investigate SN Ia progenitor systems but none have produced conclusive results. A prediction of single-degenerate models is that H- (or He-) rich material from the envelope of the companion star should be swept up by the SN ejecta in the explosion. Seven SNe Ia have been analysed to date looking for signs of H-rich material in their late-time spectra and none were detected. We present results from new late-time spectra of 11 SNe Ia obtained at the VLT using XShooter and FORS2. We present the tentative detection of H-alpha emission for SN 2013ct, corresponding to ~0.007 Msun of stripped/ablated companion star material (under the assumptions of the spectral modelling). This mass is significantly lower than expected for single-degenerate scenarios, suggesting that >0.1 Msun of H-rich is present but not observed. We do not detect H-alpha emission in the othe...
Persistent junk solutions in time-domain modeling of extreme mass ratio binaries
Field, Scott E; Lau, Stephen R
2010-01-01
In the context of metric perturbation theory for non-spinning black holes, extreme mass ratio binary (EMRB) systems are described by distributionally forced master wave equations. Numerical solution of a master wave equation as an initial boundary value problem requires initial data. However, because the correct initial data for generic-orbit systems is unknown, specification of trivial initial data is a common choice, despite being inconsistent and resulting in a solution which is initially discontinuous in time. As is well known, this choice leads to a "burst" of junk radiation which eventually propagates off the computational domain. We observe another unintended consequence of trivial initial data: development of a persistent spurious solution, here referred to as the Jost junk solution, which contaminates the physical solution for long times. This work studies the influence of both types of junk on metric perturbations, waveforms, and self-force measurements, and it demonstrates that smooth modified sour...
Exact solution of a quantum forced time-dependent harmonic oscillator
Yeon, Kyu Hwang; George, Thomas F.; Um, Chung IN
1992-01-01
The Schrodinger equation is used to exactly evaluate the propagator, wave function, energy expectation values, uncertainty values, and coherent state for a harmonic oscillator with a time dependent frequency and an external driving time dependent force. These quantities represent the solution of the classical equation of motion for the time dependent harmonic oscillator.
An Exact Solution of the Gamma Ray Burst Arrival Time Analysis Problem
Indian Academy of Sciences (India)
S. Sinha
2002-03-01
An analytical solution of the GRB arrival time analysis is presented. The errors in the position of the GRB resulting from timing and position errors of different satellites are calculated. A simple method of cross-correlating gamma ray burst time-histories is discussed.
Exact solutions of Feinberg–Horodecki equation for time-dependent anharmonic oscillator
Indian Academy of Sciences (India)
P K Bera; Tapas Sil
2013-01-01
In this work, an alternative treatment known as Nikiforov–Uvarov (NU) method is proposed to find the exact solutions of the Feinberg–Horodecki equation for the time-dependent potentials. The present procedure is illustrated with two examples: (1) time-dependent Wei Hua oscillator, (2) time-dependent Manning–Rosen potential.
Timing of examinations affects school performance differently in early and late chronotypes
van der Vinne, Vincent; Zerbini, Giulia; Siersema, Anne; Pieper, Amy; Merrow, Martha; Hut, Roelof A.; Roenneberg, Till; Kantermann, Thomas
Circadian clocks of adolescents typically run lateincluding sleep timesyet adolescents generally are expected at school early in the morning. Due to this mismatch between internal (circadian) and external (social) times, adolescents suffer from chronic sleep deficiency, which, in turn, affects
Rif1 Regulates Initiation Timing of Late Replication Origins throughout the S. cerevisiae Genome
Peace, Jared M.; Anna Ter-Zakarian; Aparicio, Oscar M
2014-01-01
Chromosomal DNA replication involves the coordinated activity of hundreds to thousands of replication origins. Individual replication origins are subject to epigenetic regulation of their activity during S-phase, resulting in differential efficiencies and timings of replication initiation during S-phase. This regulation is thought to involve chromatin structure and organization into timing domains with differential ability to recruit limiting replication factors. Rif1 has recently been identi...
Coping Strategies in Late Adolescence: Relationships to Parental Attachment and Time Perspective.
Blomgren, Anna-Sara; Svahn, Kajsa; Åström, Elisabeth; Rönnlund, Michael
2016-01-01
The authors investigated adolescents' use of coping strategies in relation to attachment to parents and time perspective. Adolescents in Grade 3 upper secondary school (M age = 18.3 years, SD = 0.6 years; n = 160) completed the Inventory of Parent and Peer Attachment, the Zimbardo Time Perspective Inventory, and the Brief COPE. Correlational analyses showed that attachment to parents was associated with a more favorable view of the past (higher past positive and lower past negative), a less fatalistic view of the present, and a more favorable view of the future (higher future positive and lower future negative). Parental attachment accounted for significant variance in composite coping scores (adaptive and maladaptive) when entered before, but not after, time perspective subscales in hierarchical regression analyses. However, time perspective (mainly present hedonistic and positive or negative future) predicted adaptive or maladaptive coping over and beyond attachment. The results are consistent with the hypothesis that most of the relationship between adolescents' attachment to parents and coping is mediated by individual differences in time perspective. By contrast, factors other than attachment to parents (e.g., temperament) must be considered to fully account for the relationship between time perspective and coping.
Time-periodic and stationary solutions to the compressible Hall-magnetohydrodynamic system
Cheng, Ming
2017-04-01
We are concerned with the 3-D compressible Hall-magnetohydrodynamic system with a time-periodic external force in a periodic domain, and establish the existence of a strong time-periodic solution under some smallness and symmetry assumptions by adapting a new approach. The basic idea of the proof is the following. First, we prove the existence of a time-periodic solution to the linearized system by applying the Tychonoff fixed point theorem combined with the energy method and the decay estimates. From the details of the proof, we see that the initial data of the time-periodic solution to the linearized system lies in some convex hull. Then, we construct a set-value function, such that the fixed point of this function is a time-periodic solution of the compressible Hall-magnetohydrodynamic system. The existence of the fixed point is obtained by the Kakutani fixed point theorem. Moreover, we establish the uniqueness of the time-periodic solution and the existence of the stationary solution.
A late time accelerated FRW model with scalar and vector fields via Noether symmetry
Vakili, Babak
2014-01-01
We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann-Robertson-Walker (FRW) model, a scalar field with potential function $V(\\phi)$ with which the gravity part of the action is minimally coupled and a vector field its kinetic energy is coupled with the scalar field by a coupling function $f(\\phi)$. Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology i...
Singular boundary method using time-dependent fundamental solution for scalar wave equations
Chen, Wen; Li, Junpu; Fu, Zhuojia
2016-11-01
This study makes the first attempt to extend the meshless boundary-discretization singular boundary method (SBM) with time-dependent fundamental solution to two-dimensional and three-dimensional scalar wave equation upon Dirichlet boundary condition. The two empirical formulas are also proposed to determine the source intensity factors. In 2D problems, the fundamental solution integrating along with time is applied. In 3D problems, a time-successive evaluation approach without complicated mathematical transform is proposed. Numerical investigations show that the present SBM methodology produces the accurate results for 2D and 3D time-dependent wave problems with varied velocities c and wave numbers k.
Timing of examinations affects school performance differently in early and late chronotypes
van der Vinne, Vincent; Zerbini, Giulia; Siersema, Anne; Pieper, Amy; Merrow, Martha; Hut, Roelof A.; Roenneberg, Till; Kantermann, Thomas
2015-01-01
Circadian clocks of adolescents typically run lateincluding sleep timesyet adolescents generally are expected at school early in the morning. Due to this mismatch between internal (circadian) and external (social) times, adolescents suffer from chronic sleep deficiency, which, in turn, affects acade
Representation of solutions and large-time behavior for fully nonlocal diffusion equations
Kemppainen, Jukka; Siljander, Juhana; Zacher, Rico
2017-07-01
We study the Cauchy problem for a nonlocal heat equation, which is of fractional order both in space and time. We prove four main theorems: a representation formula for classical solutions a quantitative decay rate at which the solution tends to the fundamental solution optimal L2-decay of mild solutions in all dimensions L2-decay of weak solutions via energy methods. The first result relies on a delicate analysis of the definition of classical solutions. After proving the representation formula we carefully analyze the integral representation to obtain the quantitative decay rates of (ii). Next we use Fourier analysis techniques to obtain the optimal decay rate for mild solutions. Here we encounter the critical dimension phenomenon where the decay rate attains the decay rate of that in a bounded domain for large enough dimensions. Consequently, the decay rate does not anymore improve when the dimension increases. The theory is markedly different from that of the standard caloric functions and this substantially complicates the analysis. Finally, we use energy estimates and a comparison principle to prove a quantitative decay rate for weak solutions defined via a variational formulation. Our main idea is to show that the L2-norm is actually a subsolution to a purely time-fractional problem which allows us to use the known theory to obtain the result.
Exact solution of the space-time fractional coupled EW and coupled MEW equations
Raslan, K. R.; S. EL-Danaf, Talaat; K. Ali, Khalid
2017-07-01
In this paper, we obtained a traveling wave solution by using the Kudryashov method for the space-time fractional nonlinear partial differential equations. The method is used to obtain the exact solutions for different types of the space-time fractional nonlinear partial differential equations, such as the space-time fractional coupled equal width wave equation (CEWE) and the space-time fractional coupled modified equal width wave equation (CMEWE), which are the important soliton equations. Both equations are reduced to ordinary differential equations by use of the fractional complex transform and of the properties of the modified Riemann-Liouville derivative. We plot the exact solutions for these equations at different time levels.
Graviton Mass Might Reduce Tension between Early and Late Time Cosmological Data
De Felice, Antonio; Mukohyama, Shinji
2017-03-01
The standard cold dark matter model with a cosmological constant (Λ -CDM) predicts a growth of structures which tends to be higher than the values of redshift space distortion (RSD) measurements if the cosmological parameters are fixed by the cosmic microwave background data. In this Letter, we point out that this discrepancy can be resolved or understood if we assume that the graviton has a small but nonzero mass. In the context of the minimal theory of massive gravity (MTMG), due to infrared Lorentz violations measurable only at present cosmological scales, the graviton acquires a mass without being haunted by unwanted extra degrees of freedom. While the so-called self-accelerating branch of cosmological solutions in the MTMG has the same phenomenology for the background as well as the scalar- and vector-type linear perturbations as the Λ CDM in general relativity (GR), it is possible to choose another branch so that the background is the same as that in GR, but the evolution of matter perturbations gets modified by the graviton mass. In studying the fit of such modified dynamics to the above-mentioned RSD measurements, we find that the Λ CDM model is less probable than the MTMG by 2 orders of magnitude. With the help of the cross-correlation between the integrated Sachs-Wolfe effect and the large-scale structure, the data also pin down the graviton mass squared around μ2≈-(3 ×10-33 eV )2, which is consistent with the latest bound |μ2|<(1.2 ×10-22 eV )2 set by the recent LIGO observation.
Graviton Mass Might Reduce Tension between Early and Late Time Cosmological Data.
De Felice, Antonio; Mukohyama, Shinji
2017-03-03
The standard cold dark matter model with a cosmological constant (Λ-CDM) predicts a growth of structures which tends to be higher than the values of redshift space distortion (RSD) measurements if the cosmological parameters are fixed by the cosmic microwave background data. In this Letter, we point out that this discrepancy can be resolved or understood if we assume that the graviton has a small but nonzero mass. In the context of the minimal theory of massive gravity (MTMG), due to infrared Lorentz violations measurable only at present cosmological scales, the graviton acquires a mass without being haunted by unwanted extra degrees of freedom. While the so-called self-accelerating branch of cosmological solutions in the MTMG has the same phenomenology for the background as well as the scalar- and vector-type linear perturbations as the ΛCDM in general relativity (GR), it is possible to choose another branch so that the background is the same as that in GR, but the evolution of matter perturbations gets modified by the graviton mass. In studying the fit of such modified dynamics to the above-mentioned RSD measurements, we find that the ΛCDM model is less probable than the MTMG by 2 orders of magnitude. With the help of the cross-correlation between the integrated Sachs-Wolfe effect and the large-scale structure, the data also pin down the graviton mass squared around μ^{2}≈-(3×10^{-33} eV)^{2}, which is consistent with the latest bound |μ^{2}|<(1.2×10^{-22} eV)^{2} set by the recent LIGO observation.
DEFF Research Database (Denmark)
Andersen, Asger Lau; Lassen, David Dreyer; Nielsen, Lasse Holbøll Westh
The budget forms the legal basis of government spending. If a budget is not in place at the beginning of the fiscal year, planning as well as current spending are jeopardized and government shutdown may result. This paper develops a continuous-time war-of-attrition model of budgeting...... in a presidential style-democracy to explain the duration of budget negotiations. We build our model around budget baselines as reference points for loss averse negotiators. We derive three testable hypotheses: there are more late budgets, and they are more late, when fiscal circumstances change; when such changes...... are negative rather than positive; and when there is divided government. We test the hypotheses of the model using a unique data set of late budgets for US state governments, based on dates of budget approval collected from news reports and a survey of state budget o¢ cers for the period 1988...
DEFF Research Database (Denmark)
Andersen, Asger Lau; Lassen, David Dreyer; Nielsen, Lasse Holbøll Westh
are negative rather than positive; and when there is divided government. We test the hypotheses of the model using a unique data set of late budgets for US state governments, based on dates of budget approval collected from news reports and a survey of state budget o¢ cers for the period 1988......The budget forms the legal basis of government spending. If a budget is not in place at the beginning of the fiscal year, planning as well as current spending are jeopardized and government shutdown may result. This paper develops a continuous-time war-of-attrition model of budgeting...... in a presidential style-democracy to explain the duration of budget negotiations. We build our model around budget baselines as reference points for loss averse negotiators. We derive three testable hypotheses: there are more late budgets, and they are more late, when fiscal circumstances change; when such changes...
Yao, Qiwei; Zheng, Rong; Xie, Guozhu; Liao, Guixiang; Du, Shasha; Ren, Chen; Li, Rong; Lin, Xiaoshan; Hu, Daokun; Yuan, Yawei
2015-01-01
High-precision radiotherapy (HPR) has established its important role in the treatment of tumors due to its precise dose distribution. Given its more complicated delivery process, HPR commonly requires more fraction delivery time (FDT). However, it is unknown whether it has an identical response of prolonged FDT on different normal tissues. Our results showed that fractionated irradiation with prolonged FDTs (15, 36, and 50 minutes) enhanced cell surviving fractions for normal tissue cells compared with irradiation with an FDT of 2 minutes. However, the late-responding normal cell line HEI-OC1 was more responsive to prolonged FDTs and demonstrated higher surviving fractions and significantly decreased apoptosis and DNA damage compared to the acute-responding normal cell line HaCaT. Increased autophagy mediated via the ATM-AMPK pathway was observed in HEI-OC1 cells compared with HaCaT cells when irradiated with prolonged FDTs. Furthermore, treatment with the autophagy inhibitor 3-MA or ATM inhibitor KU55933 resulted in enhanced ROS accumulation and attenuation of the effect of prolonged FDT-mediated protection on irradiated HEI-OC1 cells. Our results indicated that late-responding normal tissue cells benefitted more from prolonged FDTs compared with acute-responding tissue cells, which was mainly attributed to enhanced cytoprotective autophagy mediated via the ATM/AMPK signaling pathway. PMID:25766900
Timing System Solution for MedAustron; Real-time Event and Data Distribution Network
Štefanič, R; Dedič, J; Gutleber, J; Moser, R
2011-01-01
MedAustron is an ion beam research and therapy centre under construction in Wiener Neustadt, Austria. The facility features a synchrotron particle accelerator for light ions. The timing system for this class of accelerators has been developed in close collaboration between MedAustron and Cosylab. Mitigating economical and technological risks, we have chosen a proven, widely used Micro Research Finland (MRF) timing equipment and redesigned its FPGA firmware, extending its high-logic services above transport layer, as required by machine specifics. We obtained a generic real-time broadcast network for coordinating actions of a compact, pulse-to-pulse modulation based particle accelerator. High-level services include support for virtual accelerators and a rich selection of event response mechanisms. The system uses a combination of a real-time link for downstream events and a non-real-time link for upstream messaging and non time-critical communication. It comes with National Instruments LabVI...
Energy Technology Data Exchange (ETDEWEB)
Doeblin, Patrick, E-mail: Patrick.doeblin@charite.de [Department of Cardiology, Charité – Universitätsmedizin Berlin, Charité Campus Benjamin Franklin, Berlin (Germany); Schilling, Rene, E-mail: rene.schilling@charite.de [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); Wagner, Moritz, E-mail: moritz.wagner@charite.de [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); Luhur, Reny, E-mail: renyluhur@yahoo.com [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); Huppertz, Alexander, E-mail: alexander.huppertz@charite.de [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); Imaging Science Institute, Charité, Berlin (Germany); Hamm, Bernd, E-mail: bernd.hamm@charite.de [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); Taupitz, Matthias, E-mail: matthias.taupitz@harite.de [Department of Radiology, Charité – Universitätsmedizin Berlin, Charité Campus Mitte, Berlin (Germany); and others
2014-04-15
Purpose: To evaluate T1-relaxation times of chronic myocardial infarction (CMI) using gadobutrol and gadopentetate dimeglumine (Gd-DTPA) over time and to determine the optimal imaging window for late enhancement imaging with both contrast agents. Material and methods: Twelve patients with CMI were prospectively included and examined on a 1.5 T magnetic resonance (MR) system using relaxivity-adjusted doses of gadobutrol (0.15 mmol/kg) and Gd-DTPA (0.2 mmol/kg) in random order. T1-relaxation times of remote myocardium (RM), infarcted myocardium (IM), and left ventricular cavity (LVC) were assessed from short-axis TI scout imaging using the Look–Locker approach and compared intraindividually using a Wilcoxon paired signed-rank test (α < 0.05). Results: Within 3 min of contrast agent administration (CA), IM showed significantly lower T1-relaxation times than RM with both contrast agents, indicating beginning cardiac late enhancement. Differences between gadobutrol and Gd-DTPA in T1-relaxation times of IM and RM were statistically not significant through all time points. However, gadobutrol led to significantly higher T1-relaxation times of LVC than Gd-DTPA from 6 to 9 min (220 ± 15 ms vs. 195 ± 30 ms p < 0.01) onwards, resulting in a significantly greater ΔT1 of IM to LVC at 9–12 min (−20 ± 35 ms vs. 0 ± 35 ms, p < 0.05) and 12–15 min (−25 ± 45 ms vs. −10 ± 60 ms, p < 0.05). Using Gd-DTPA, comparable ΔT1 values were reached only after 25–35 min. Conclusion: This study indicates good delineation of IM to RM with both contrast agents as early as 3 min after administration. However, we found significant differences in T1 relaxation times with greater ΔT1 IM–LVC using 0.15 mmol/kg gadobutrol compared to 0.20 mmol/kg Gd-DTPA after 9–15 min post-CA suggesting earlier differentiability of IM and LVC using gadobutrol.
Socorro, J.; Toledo Sesma, L.
2016-03-01
In this work we construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus without the contributions of fluxes as first approximation. This approach is applied to anisotropic cosmological Bianchi type II model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Also, we present some solutions to the corresponding Wheeler-DeWitt (WDW) equation in the context of Standard Quantum Cosmology and we claim that these quantum solution are generic in the moduli scalar field for all Bianchi Class A models. Also we give the relation to these solutions for asymptotic behavior to large argument in the corresponding quantum solution in the gravitational variables and compare with Bohm's solutions, finding that this corresponds to the lowest-order WKB approximation.
Socorro, J
2015-01-01
In this work we construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus without the contributions of fluxes as first approximation. This approach is applied to anisotropic cosmological Bianchi type II model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Also, we present some solutions to the corresponding Wheeler-DeWitt (WDW) equation in the context of Standard Quantum Cosmology and we claim that these quantum solution are generic in the moduli scalar field for all Bianchi Class A models. Also we gives the relation to these solutions for asymptotic behavior to large argument in the corresponding quantum solution in the gravitational variables and is compared with the Bohm's solutions, finding that this corresponds to lowest-order WKB approximation.
Avitia, Roberto L; Reyna, Marco A; Bravo-Zanoguera, Miguel E; Cetto, Lucio A
2013-04-01
Ventricular late potentials (VLPs) are small-amplitude waves with a short duration that appear at the end part of the QRS complex, making a QRS complex duration larger. The signal-averaged electrocardiography (ECG) technique enhances VLPs and beats, assuming noise as the only random variable. However, ECG signals are not completely stationary and different elongations appear in both time and amplitude in each beat. This research proposes to use piecewise linear approximation to segment each beat and performs the alignment of the beats using the technique known as derivative dynamic time-warping to have beats better aligned and consequently enhance the presence of VLPs. We recorded high-resolution ECGs (HRECGs) from 50 subjects in supine position with no heart-stroke antecedents. VLPs were created synthetically and added to the HRECGs. Two cases were evaluated: (i) duration of the QRS complexes with VLPs without beats alignment, and (ii) duration of QRS complexes with VLPs using beats alignment in time and amplitude. Considering QRS duration as an indicative of VLP presence, results show that when using beats alignment in time and amplitude it is possible to reach a sensitivity of 0.96 and a specificity of 0.52, as opposed to 0.72 and 0.40, respectively, when using only averaging without beats alignment in time and amplitude.
Directory of Open Access Journals (Sweden)
Yongkun Li
2011-01-01
Full Text Available Firstly, we propose a concept of uniformly almost periodic functions on almost periodic time scales and investigate some basic properties of them. When time scale T=ℝ or ℤ, our definition of the uniformly almost periodic functions is equivalent to the classical definitions of uniformly almost periodic functions and the uniformly almost periodic sequences, respectively. Then, based on these, we study the existence and uniqueness of almost periodic solutions and derive some fundamental conditions of admitting an exponential dichotomy to linear dynamic equations. Finally, as an application of our results, we study the existence of almost periodic solutions for an almost periodic nonlinear dynamic equations on time scales.
Epidural top-up solutions for emergency caesarean section: a comparison of preparation times.
Lucas, D N; Borra, P J; Yentis, S M
2000-04-01
We compared the preparation times of three solutions commonly used for epidural top-up for emergency Caesarean section. Twenty-two anaesthetists were asked to prepare fresh solutions in random order as quickly as possible: 0.5% bupivacaine 20 ml (B); 2% lidocaine 20 ml with 1:200,000 epinephrine (LE); and 0.5% bupivacaine 10 ml and 2% lidocaine 10 ml with 1:200,000 epinephrine and 8.4% sodium bicarbonate 2 ml (BLEB). Preparation times for B were approximately half of those for LE, which in turn were approximately half of those for BLEB (P = 0.0001). If local anaesthetic solutions with additives such as epinephrine or bicarbonate are prepared just before emergency Caesarean section, any possible reduction in onset time that they might afford may be offset by the additional preparation time required.
Hackmann, Eva
2015-01-01
The complete set of analytic solutions of the geodesic equation in a Schwarzschild--(anti-)de Sitter space--time is presented. The solutions are derived from the Jacobi inversion problem restricted to the set of zeros of the theta function, called the theta divisor. In its final form the solutions can be expressed in terms of derivatives of Kleinian sigma functions. The different types of the resulting orbits are characterized in terms of the conserved energy and angular momentum as well as the cosmological constant. Using the analytical solution, the question whether the cosmological constant could be a cause of the Pioneer Anomaly is addressed. The periastron shift and its post--Schwarzschild limit is derived. The developed method can also be applied to the geodesic equation in higher dimensional Schwarzschild space--times.
Arqub, Omar Abu; El-Ajou, Ahmad; Momani, Shaher
2015-07-01
Building fractional mathematical models for specific phenomena and developing numerical or analytical solutions for these fractional mathematical models are crucial issues in mathematics, physics, and engineering. In this work, a new analytical technique for constructing and predicting solitary pattern solutions of time-fractional dispersive partial differential equations is proposed based on the generalized Taylor series formula and residual error function. The new approach provides solutions in the form of a rapidly convergent series with easily computable components using symbolic computation software. For method evaluation and validation, the proposed technique was applied to three different models and compared with some of the well-known methods. The resultant simulations clearly demonstrate the superiority and potentiality of the proposed technique in terms of the quality performance and accuracy of substructure preservation in the construct, as well as the prediction of solitary pattern solutions for time-fractional dispersive partial differential equations.
Late-time Structure of the Bunch-Davies FRW Wavefunction
Konstantinidis, George; Shaghoulian, Edgar
2016-01-01
In this short note we organize a perturbation theory for the Bunch-Davies wavefunction in flat, accelerating cosmologies. The calculational technique avoids the in-in formalism and instead uses an analytic continuation from Euclidean signature. We will consider both massless and conformally coupled self-interacting scalars. These calculations explicitly illustrate two facts. The first is that IR divergences get sharper as the acceleration slows. The second is that UV-divergent contact terms in the Euclidean computation can contribute to the absolute value of the wavefunction in Lorentzian signature. Here UV divergent refers to terms involving inverse powers of the radial cutoff in the Euclidean computation. In Lorentzian signature such terms encode physical time dependence of the wavefunction.
Late-time structure of the Bunch-Davies FRW wavefunction
Energy Technology Data Exchange (ETDEWEB)
Konstantinidis, George; Mahajan, Raghu [Stanford Institute for Theoretical Physics, Stanford University,382 via Pueblo, Stanford CA (United States); Shaghoulian, Edgar [Department of Physics, University of California Santa Barbara,Santa Barbara CA (United States)
2016-10-19
In this short note we organize a perturbation theory for the Bunch-Davies wavefunction in flat, accelerating cosmologies. The calculational technique avoids the in-in formalism and instead uses an analytic continuation from Euclidean signature. We will consider both massless and conformally coupled self-interacting scalars. These calculations explicitly illustrate two facts. The first is that IR divergences get sharper as the acceleration slows. The second is that UV-divergent contact terms in the Euclidean computation can contribute to the absolute value of the wavefunction in Lorentzian signature. Here UV divergent refers to terms involving inverse powers of the radial cutoff in the Euclidean computation. In Lorentzian signature such terms encode physical time dependence of the wavefunction.
Bean, R; Bean, Rachel; Magueijo, Joao
2001-01-01
Quintessence scenarios provide a simple explanation for the observed acceleration of the Universe. Yet, explaining why acceleration did not start a long time ago remains a challenge. The idea that the transition from radiation to matter domination played a dynamical role in triggering acceleration has been put forward in various guises. We propose a simple dilaton-derived quintessence model in which temporary vacuum domination is naturally triggered by the radiation to matter transition. In this model Einstein's gravity is preserved but quintessence couples non-minimally to the cold dark matter, but not to ``visible'' matter. Such couplings have been attributed to the dilaton in the low-energy limit of string theory beyond tree level. We also show how a cosmological constant in the string frame translates into a quintessence-type of potential in the atomic frame.
Mitchell, Niall A.; Frawley, Patrick J.; Ó'Ciardhá, Clifford T.
2011-04-01
A study of the nucleation kinetics for cooling crystallisation of paracetamol-ethanol solutions in a batch reactor is described in this paper. Induction time experiments were conducted in order to estimate the nucleation kinetics of the system. Measured induction times can be affected by numerous process parameters, such as concentration, agitation rate and solution hydrodynamics. The theoretical approach of Kubota (2008) [14] was employed to estimate the nucleation kinetics, where the induction time is assumed to correspond to the time required for the number density of grown crystals to reach a fixed value. The induction time was observed to be independent of the solution temperature. This is suggested from Kubota's theory, in agreement with previous work and serves to further validate the induction time theory of Kubota. In this investigation, induction times were observed to decrease significantly with increased levels of agitation. Furthermore, the presence of wall baffles in the reaction vessel was also found to significantly reduce the measured induction times for the solution system.
Unique Existence Theorem of Solution of Almost Periodic Differential Equations on Time Scales
Directory of Open Access Journals (Sweden)
Meng Hu
2012-01-01
Full Text Available By using the theory of calculus on time scales and M-matrix theory, the unique existence theorem of solution of almost periodic differential equations on almost periodic time scales is established. The result can be used to a large of dynamic systems.
Unique Existence Theorem of Solution of Almost Periodic Differential Equations on Time Scales
Meng Hu; Lili Wang
2012-01-01
By using the theory of calculus on time scales and M-matrix theory, the unique existence theorem of solution of almost periodic differential equations on almost periodic time scales is established. The result can be used to a large of dynamic systems.
Error estimates for asymptotic solutions of dynamic equations on time scales
Directory of Open Access Journals (Sweden)
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].
GLOBAL SOLUTION AND ITS LONG TIME BEHAVIOR FOR THE GENERALIZED LONG-SHORT WAVE EQUATIONS
Institute of Scientific and Technical Information of China (English)
Zhang Ruifeng; Guo Boling
2005-01-01
The long time behavior of the solutions of the generalized long-short wave equations with dissipation term is studied. The existence of global attractor of the initial periodic boundary value is proved by means of a uniform a priori estimate for time. And also the dimensions of the global attractor are estimated.
Stability and Convergence of Solutions to Volterra Integral Equations on Time Scales
Directory of Open Access Journals (Sweden)
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.
Schmidt, Moritz; Heck, Stephanie; Bosbach, Dirk; Ganschow, Steffen; Walther, Clemens; Stumpf, Thorsten
2013-01-01
We present a comprehensive study of the solid solution system Ca-2(MoO4)(2)-NaGd(MoO4)(2) on the molecular scale, by means of site-selective time resolved laser fluorescence spectroscopy (TRLFS). Eu3+ is used as a trace fluorescent probe, homogeneously substituting for Gd3+ in the solid solution crystal structure. Site-selective TRLFS of a series of polycrystalline samples covering the whole composition range of the solid solution series from 10% substitution of Ca2+ to the NaGd end-member re...
Stability and periodicity of solutions for delay dynamic systems on time scales
Directory of Open Access Journals (Sweden)
Zhi-Qiang Zhu
2014-04-01
Full Text Available This article concerns the stability and periodicity of solutions to the delay dynamic system $$ x^{\\triangle}(t=A(t x(t + F(t, x(t, x(g(t+C(t $$ on a time scale. By the inequality technique for vectors, we obtain some stability criteria for the above system. Then, by using the Horn fixed point theorem, we present some conditions under which our system is asymptotically periodic and its periodic solution is unique. In particular, the periodic solution is positive under proper assumptions.
Directory of Open Access Journals (Sweden)
S. Das
2013-12-01
Full Text Available In this article, optimal homotopy-analysis method is used to obtain approximate analytic solution of the time-fractional diffusion equation with a given initial condition. The fractional derivatives are considered in the Caputo sense. Unlike usual Homotopy analysis method, this method contains at the most three convergence control parameters which describe the faster convergence of the solution. Effects of parameters on the convergence of the approximate series solution by minimizing the averaged residual error with the proper choices of parameters are calculated numerically and presented through graphs and tables for different particular cases.
Spherical Wave Propagation in a Poroelastic Medium with Infinite Permeability: Time Domain Solution
Directory of Open Access Journals (Sweden)
Mehmet Ozyazicioglu
2014-01-01
Full Text Available Exact time domain solutions for displacement and porepressure are derived for waves emanating from a pressurized spherical cavity, in an infinitely permeable poroelastic medium with a permeable boundary. Cases for blast and exponentially decaying step pulse loadings are considered; letter case, in the limit as decay constant goes to zero, also covers the step (uniform pressure. Solutions clearly show the propagation of the second (slow p-wave. Furthermore, Biot modulus Q is shown to have a pronounced influence on wave propagation characteristics in poroelastic media. Results are compared with solutions in classical elasticity theory.
Ravi Kanth, A. S. V.; Aruna, K.
2016-12-01
In this paper, we present fractional differential transform method (FDTM) and modified fractional differential transform method (MFDTM) for the solution of time fractional Black-Scholes European option pricing equation. The method finds the solution without any discretization, transformation, or restrictive assumptions with the use of appropriate initial or boundary conditions. The efficiency and exactitude of the proposed methods are tested by means of three examples.
Exact Analytical Solutions in Bose-Einstein Condensates with Time-Dependent Atomic Scattering Length
Institute of Scientific and Technical Information of China (English)
CHEN Yong; LI Biao; ZHENG Yu
2007-01-01
In the paper, the generalized Riccati equation rational expansion method is presented. Making use of the method and symbolic computation, we present three families of exact analytical solutions of Bose-Einstein condensates with the time-dependent interatomic interaction in an expulsive parabolic potential. Then the dynamics of two anlytical solutions are demonstrated by computer simulations under some selectable parameters including the Feshbach-managed nonlinear coefficient and the hyperbolic secant function coefficient.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In this paper, global exponential stability of almost periodic solution of cellular neural networks with time-varing delays (CNNVDs) is considered. By using the methods of the topological degree theory and generalized Halanay inequality, a few new applicable criteria are established for the existence and global exponential stability of almost periodic solution. Some previous results are improved and extended in this letter and one example is given to illustrate the effectiveness of the new results.
Existence of Almost-Periodic Solutions for Lotka-Volterra Cooperative Systems with Time Delay
Directory of Open Access Journals (Sweden)
Kaihong Zhao
2012-01-01
Full Text Available This paper considers the existence of positive almost-periodic solutions for almost-periodic Lotka-Volterra cooperative system with time delay. By using Mawhin’s continuation theorem of coincidence degree theory, sufficient conditions for the existence of positive almost-periodic solutions are obtained. An example and its simulation figure are given to illustrate the effectiveness of our results.
Soliton solutions of some nonlinear evolution equations with time-dependent coefficients
Indian Academy of Sciences (India)
Hitender Kumar; Anand Malik; Fakir Chand
2013-02-01
In this paper, we obtain exact soliton solutions of the modified KdV equation, inho-mogeneous nonlinear Schrödinger equation and (, ) equation with variable coefficients using solitary wave ansatz. The constraint conditions among the time-dependent coefficients turn out as necessary conditions for the solitons to exist. Numerical simulations for dark and bright soliton solutions for the mKdV equation are also given.
Li,Quan-Lin; Lui, John C. S.
2010-01-01
In this paper, we provide a novel matrix-analytic approach for studying doubly exponential solutions of randomized load balancing models (also known as supermarket models) with Markovian arrival processes (MAPs) and phase-type (PH) service times. We describe the supermarket model as a system of differential vector equations by means of density dependent jump Markov processes, and obtain a closed-form solution with a doubly exponential structure to the fixed point of the system of differential...
Li, Quan-Lin; Lui, John C. S.
2010-01-01
In this paper, we provide a novel matrix-analytic approach for studying doubly exponential solutions of randomized load balancing models (also known as supermarket models) with Markovian arrival processes (MAPs) and phase-type (PH) service times. We describe the supermarket model as a system of differential vector equations by means of density dependent jump Markov processes, and obtain a closed-form solution with a doubly exponential structure to the fixed point of the system of differential...
Existence of Weak Solutions for Nonlinear Time-Fractional p-Laplace Problems
Directory of Open Access Journals (Sweden)
Meilan Qiu
2014-01-01
Full Text Available The existence of weak solution for p-Laplace problem is studied in the paper. By exploiting the relationship between the Nehari manifold and fibering maps and combining the compact imbedding theorem and the behavior of Palais-Smale sequences in the Nehari manifold, the existence of weak solutions is established. By means of the Arzela-Ascoli fixed point theorem, some existence results of the corresponding time-fractional equations of the p-Laplace problem are obtained.
Directory of Open Access Journals (Sweden)
Koonin Eugene V
2011-05-01
Full Text Available Abstract Background Accurate estimation of the divergence time of the extant eukaryotes is a fundamentally important but extremely difficult problem owing primarily to gross violations of the molecular clock at long evolutionary distances and the lack of appropriate calibration points close to the date of interest. These difficulties are intrinsic to the dating of ancient divergence events and are reflected in the large discrepancies between estimates obtained with different approaches. Estimates of the age of Last Eukaryotic Common Ancestor (LECA vary approximately twofold, from ~1,100 million years ago (Mya to ~2,300 Mya. Results We applied the genome-wide analysis of rare genomic changes associated with conserved amino acids (RGC_CAs and used several independent techniques to obtain date estimates for the divergence of the major lineages of eukaryotes with calibration intervals for insects, land plants and vertebrates. The results suggest an early divergence of monocot and dicot plants, approximately 340 Mya, raising the possibility of plant-insect coevolution. The divergence of bilaterian animal phyla is estimated at ~400-700 Mya, a range of dates that is consistent with cladogenesis immediately preceding the Cambrian explosion. The origin of opisthokonts (the supergroup of eukaryotes that includes metazoa and fungi is estimated at ~700-1,000 Mya, and the age of LECA at ~1,000-1,300 Mya. We separately analyzed the red algal calibration interval which is based on single fossil. This analysis produced time estimates that were systematically older compared to the other estimates. Nevertheless, the majority of the estimates for the age of the LECA using the red algal data fell within the 1,200-1,400 Mya interval. Conclusion The inference of a "young LECA" is compatible with the latest of previously estimated dates and has substantial biological implications. If these estimates are valid, the approximately 1 to 1.4 billion years of evolution of
Timing and Awareness of Movement Decisions: Does Consciousness Really Come Too Late?
Directory of Open Access Journals (Sweden)
Adrian G Guggisberg
2013-07-01
Full Text Available Since Libet’s seminal observation that a brain potential related to movement preparation occurs before participants report to be aware of their movement intention, it has been debated whether consciousness has causal influence on movement decisions. Here we review recent advances that provide new insights into the dynamics of human decision-making and question the validity of different markers used for determining the onset of neural and conscious events. Motor decisions involve multiple stages of goal evaluation, intention formation, and action execution. While the validity of the Bereitschaftspotential as index of neural movement preparation is controversial, improved neural markers are able to predict decision outcome even at early stages. Participants report being conscious of their decisions only at the time of final intention formation, just before the primary motor cortex starts executing the chosen action. However, accumulating evidence suggests that this is an artifact of Libet’s clock method used for assessing consciousness. More refined methods suggest that intention consciousness does not appear instantaneously but builds up progressively. In this view, early neural markers of decision outcome are not unconscious but simply reflect conscious goal evaluation stages which are not final yet and therefore not reported with the clock method. Alternatives to the Libet clock are discussed that might allow for assessment of consciousness during decision making with improved sensitivity to early decision stages and with less influence from meta-conscious and perceptual inferences.
Testing the Magnetar Model via Late Time Radio Observations of Two Macronova Candidates
Horesh, Assaf; Piran, Tsvi; Nakar, Ehud; Hancock, Paul
2016-01-01
Compact binary mergers may have already been observed as they are the leading model for short gamma-ray bursts (sGRBs). Radioactive decay within the ejecta from these mergers is expected to produce an infra-red flare, dubbed macronova (or kilonova), on a time scale of a week. Recently two such macronova candidates were identified in followup observations of sGRBs, strengthening the possibility that those indeed arise from mergers. The same ejecta will also produce a long term (months to years) radio emission due to its interaction with the surrounding ISM. In search for this emission, we observed the two macronova candidates, GRB 130603B and GRB 060614 with the Jansky very large array (VLA) and the Australia Telescope Compact Array (ATCA). Our observations resulted in null-detections, putting strong upper limits on the kinetic energy and mass of the ejecta. A possible outcome of a merger is a highly magnetized neutron star (a magnetar), which has been suggested as the central engine for GRBs. Such a magnetar ...
Energy Technology Data Exchange (ETDEWEB)
Dimitriu-Leen, Aukelien C.; Veltman, Caroline E.; Bax, Jeroen J.; Scholte, Arthur J.H.A. [Leiden University Medical Center, Department of Cardiology, Leiden (Netherlands); Gimelli, Alessia [Fondazione Toscana/CNR Gabriele Monasterio, Pisa (Italy); Al Younis, Imad [VieCuri, Department of Nuclear Medicine, Venlo (Netherlands); Verberne, Hein J. [Academic Medical Center, Department of Nuclear Medicine, Amsterdam (Netherlands); Wolterbeek, Ron [Leiden University Medical Center, Department of Medical Statistics and Bio-informatics, Leiden (Netherlands); Zandbergen-Harlaar, Silvia [Leiden University Medical Center, Department of Nuclear Medicine, Leiden (Netherlands)
2016-02-15
The aim of this study was to investigate whether performing the late cardiac {sup 123}I-metaiodobenzylguanidine (MIBG) scan earlier than 4 h post-injection (p.i.) has relevant impact on the late heart to mediastinum ratio (H/M ratio) in patients with heart failure (HF). Forty-nine patients with HF (median left ventricular ejection fraction of 31 %, 51 % ischaemic HF) referred for cardiac {sup 123}I-MIBG scintigraphy were scanned at 15 min (early) p.i. and at 1, 2, 3 and 4 h (late) p.i. of {sup 123}I-MIBG. Late H/M ratios were calculated and evaluated using a linear mixed model with the mean late H/M ratio at 4 h p.i. as a reference. A difference in late H/M ratios of more than 0.10 between the different acquisition times in comparison with the late H/M ratio at 4 h p.i. was considered as clinically relevant. Statistically significant mean differences were observed between the late H/M ratios at 1, 2 and 3 h p.i. compared with the late H/M ratio at 4 h p.i. (0.09, 0.05 and 0.02, respectively). However, the mean differences did not exceed the cut-off value of 0.10. On an individual patient level, compared to the late H/M ratio at 4 h p.i., the late H/M ratios at 1, 2 and 3 h p.i. differed more than 0.10 in 24 (50 %), 9 (19 %) and 2 (4 %) patients, respectively. Variation in acquisition time of {sup 123}I-MIBG between 2 and 4 h p.i. does not lead to a clinically significant change in the late H/M ratio. An earlier acquisition time seems to be justified and may warrant a more time-efficient cardiac {sup 123}I-MIBG imaging protocol. (orig.)
Analytic solutions for seismic travel time and ray path geometry through simple velocity models.
Energy Technology Data Exchange (ETDEWEB)
Ballard, Sanford
2007-12-01
The geometry of ray paths through realistic Earth models can be extremely complex due to the vertical and lateral heterogeneity of the velocity distribution within the models. Calculation of high fidelity ray paths and travel times through these models generally involves sophisticated algorithms that require significant assumptions and approximations. To test such algorithms it is desirable to have available analytic solutions for the geometry and travel time of rays through simpler velocity distributions against which the more complex algorithms can be compared. Also, in situations where computational performance requirements prohibit implementation of full 3D algorithms, it may be necessary to accept the accuracy limitations of analytic solutions in order to compute solutions that satisfy those requirements. Analytic solutions are described for the geometry and travel time of infinite frequency rays through radially symmetric 1D Earth models characterized by an inner sphere where the velocity distribution is given by the function V (r) = A-Br{sup 2}, optionally surrounded by some number of spherical shells of constant velocity. The mathematical basis of the calculations is described, sample calculations are presented, and results are compared to the Taup Toolkit of Crotwell et al. (1999). These solutions are useful for evaluating the fidelity of sophisticated 3D travel time calculators and in situations where performance requirements preclude the use of more computationally intensive calculators. It should be noted that most of the solutions presented are only quasi-analytic. Exact, closed form equations are derived but computation of solutions to specific problems generally require application of numerical integration or root finding techniques, which, while approximations, can be calculated to very high accuracy. Tolerances are set in the numerical algorithms such that computed travel time accuracies are better than 1 microsecond.
Energy Technology Data Exchange (ETDEWEB)
Huang Zhenkun [Department of Mathematics, School of Sciences, Zhejiang University, Hangzhou, Zhejiang 310027 (China) and School of Sciences, Jimei University, Xiamen, Fujian 361021 (China)]. E-mail: huangdoc@tom.com; Wang Xinghua [Department of Mathematics, School of Sciences, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Gao Feng [School of Sciences, Jimei University, Xiamen, Fujian 361021 (China)
2006-02-06
In this Letter, we discuss discrete-time analogue of a continuous-time cellular neural network. Sufficient conditions are obtained for the existence of a unique almost periodic sequence solution which is globally attractive. Our results demonstrate dynamics of the formulated discrete-time analogue as mathematical models for the continuous-time cellular neural network in almost periodic case. Finally, a computer simulation illustrates the suitability of our discrete-time analogue as numerical algorithms in simulating the continuous-time cellular neural network conveniently.
Chen, Han
2016-01-01
Many control applications can be formulated as optimization constrained by conservation laws. Such optimization can be efficiently solved by gradient-based methods, where the gradient is obtained through the adjoint method. Traditionally, the adjoint method has not been able to be implemented in "gray-box" conservation law simulations. In gray-box simulations, the analytical and numerical form of the conservation law is unknown, but the space-time solution of relevant flow quantities is available. Without the adjoint gradient, optimization can be challenging for problems with many control variables. However, much information about the gray-box simulation is contained in its space-time solution, which motivates us to estimate the adjoint gradient by leveraging the space-time solution. This article considers a type of gray-box simulations where the flux function is partially unknown. A method is introduced to estimate the adjoint gradient at a cost independent of the number of control variables. The method firs...
On the DC loop modes in the MOT solution of the time domain EFIE
Shi, Yifei
2014-07-01
When marching-on-in-time (MOT) method is applied to solve the time domain electric field integral equation (TD-EFIE), DC loop modes are always observed in the solution. In theory these modes should not be observed since they do not satisfy the relaxed initial conditions. Their appearance is attributed to numerical errors. It is shown here that when Rao-Wilton-Glisson basis and Lagrange interpolation functions are used to discretize the TD-EFIE, errors due to this space-time discretization have zero impact on the DC loop modes. Numerical experiments demonstrate that the numerical errors due to approximate solution of the MOT matrix system have more dominant impact on DC loop modes in the MOT solution.
A theory of time-dependent compaction by fracturing and pressure solution
Keszthelyi, Daniel; Dysthe, Dag Kristian; Jamtveit, Bjørn
2016-04-01
Porous rocks under compressional stress conditions are subject to compaction creep. A previous micromechanical model, dealing with (partially) water-filled carbonates was able to predict strain rates of the compaction at macroscopic level by combining microscopic fracturing and pressure solution at microscopic level and using a statistical upscaling. Building on this model we investigated the time-dependence of the pressure solution and the overall compaction and created a new theory of compaction by developing a statistical theory of time-dependence of pressure solution. Long-term creep experiments on carbonate samples were used to test the model which was able to predict the rate of compaction and its time-dependence in largely different effective stress, temperature and fluid chemistry conditions.
Directory of Open Access Journals (Sweden)
Mohammad Hossein Zarei
2016-01-01
Full Text Available Job selection and scheduling are among the most important decisions for production planning in today’s manufacturing systems. However, the studies that take into account both problems together are scarce. Given that such problems are strongly NP-hard, this paper presents an approach based on two heuristic algorithms for simultaneous job selection and scheduling. The objective is to select a subset of candidate jobs and schedule them in such a way that the total net profit is maximized. The cost components considered here include jobs' processing costs and weighted earliness/tardiness penalties. Two heuristic algorithms; namely scatter search (SS and simulated annealing (SA, were employed to solve the problem for single machine environments. The algorithms were applied to several examples of different sizes with sequence-dependent setup times. Computational results were compared in terms of quality of solutions and convergence speed. Both algorithms were found to be efficient in solving the problem. While SS could provide solutions with slightly higher quality for large size problems, SA could achieve solutions in a more reasonable computational time.
van den Brand, Marre; Peters, Remco P H; Catsburg, Arnold; Rubenjan, Anna; Broeke, Ferdi J; van den Dungen, Frank A M; van Weissenbruch, Mirjam M; van Furth, A Marceline; Kõressaar, Triinu; Remm, Maido; Savelkoul, Paul H M; Bos, Martine P
2014-11-01
The diagnosis of late onset sepsis (LOS), a severe condition with high prevalence in preterm infants, is hampered by the suboptimal sensitivity and long turnaround time of blood culture. Detection of the infecting pathogen directly in blood by PCR would provide a much more timely result. Unfortunately, PCR-based assays reported so far are labor intensive and often lack direct species identification. Therefore we developed a real-time multiplex PCR assay tailored to LOS diagnosis which is easy-to-use, is applicable on small blood volumes and provides species-specific results within 4h. Species-specific PCR assays were selected from literature or developed using bioinformatic tools for the detection of the most prevalent etiologic pathogens: Enterococcus faecalis, Staphylococcus aureus, Staphylococcus spp., Streptococcus agalactiae, Escherichia coli, Pseudomonas aeruginosa, Klebsiella spp. and Serratia marcescens. The PCR assays showed 100% specificity, full coverage of the target pathogens and a limit of detection (LOD) of ≤10CFUeq./reaction. These LOD values were maintained in the multiplex format or when bacterial DNA was isolated from blood. Clinical evaluation showed high concordance between the multiplex PCR and blood culture. In conclusion, we developed a multiplex PCR that allows the direct detection of the most important bacterial pathogens causing LOS in preterm infants.
Short Time Uniqueness Results for Solutions of Nonlocal and Non-monotone Geometric Equations
Barles, Guy; Mitake, Hiroyoshi
2010-01-01
We describe a method to show short time uniqueness results for viscosity solutions of general nonlocal and non-monotone second-order geometric equations arising in front propagation problems. Our method is based on some lower gradient bounds for the solution. These estimates are crucial to obtain regularity properties of the front, which allow to deal with nonlocal terms in the equations. Applications to short time uniqueness results for the initial value problems for dislocation type equations, asymptotic equations of a FitzHugh-Nagumo type system and equations depending on the Lebesgue measure of the fronts are presented.
Time dependent quantum harmonic oscillator subject to a sudden change of mass: continuous solution
Energy Technology Data Exchange (ETDEWEB)
Moya C, H. [INAOE, Coordinacion de Optica, AP 51 y 216, 72000 Puebla (Mexico); Fernandez G, M. [Depto. de Fisica, CBI, Universidad Autonoma Metropolitana - Iztapalapa, 09340, Mexico, D.F. AP 55-534 (Mexico)
2007-07-01
We show that a harmonic oscillator subject to a sudden change of mass produces squeezed states. Our study is based on an approximate analytic solution to the time-dependent harmonic oscillator equation with a sub period function parameter. This continuous treatment differs from former studies that involve the matching of two time-independent solutions at the discontinuity. This formalism requires an ad hoc transformation of the original differential equation and is also applicable for rapid, although not necessarily instantaneous, mass variations. (Author)
Asymptotic Expansion of the Solutions to Time-Space Fractional Kuramoto-Sivashinsky Equations
Directory of Open Access Journals (Sweden)
Weishi Yin
2016-01-01
Full Text Available This paper is devoted to finding the asymptotic expansion of solutions to fractional partial differential equations with initial conditions. A new method, the residual power series method, is proposed for time-space fractional partial differential equations, where the fractional integral and derivative are described in the sense of Riemann-Liouville integral and Caputo derivative. We apply the method to the linear and nonlinear time-space fractional Kuramoto-Sivashinsky equation with initial value and obtain asymptotic expansion of the solutions, which demonstrates the accuracy and efficiency of the method.
Directory of Open Access Journals (Sweden)
Valmir Martins Monteiro
2014-12-01
Full Text Available This work studies the microstructural characteristics and mechanical properties for different aluminium alloys (1100, 3104 and 8011 hot rolled sheets that were subjected to a solution heat treatment with distinct soaking times, in order to promote microstructural and mechanical changes on these alloys with solute fractions slightly above the maximum solubility limit. Scanning Electronic Microscopy (SEM / Energy Dispersive Spectroscopy X-Ray (EDS, X-Ray Diffraction (XRD and Hardness Tests were employed to observe the microstructural / compositional and mechanical evaluation. For the 1100 and 8011 alloys the more suitable soaking time occur between 1 and 2 hours, and for the 3104 alloy occurs between 2 and 3 hours.
Directory of Open Access Journals (Sweden)
Kimihiro Okubo
1998-01-01
Full Text Available The definition of late-phase response (LPR associated with nasal allergy is not as clear as that associated with asthma. Furthermore, LPR and immediate-phase response often act in concert to produce confounding symptoms due to repeated attacks over a short period of time. We examined the nasal airway resistance (NAR, allergic symptoms, eosinophil cationic protein and histamine concentration in nasal surface tissue 30 min before, and 10 min, 1, 3, 5, 7 and 9 h after a house dust (HD nasal challenge test was performed twice on 10 patients with HD perennial nasal allergy. Nasal airway resistance readings after the HD nasal challenge test were classified into three types based on changes in NAR: type I (short-lasting, five cases; type II (prolonged, eight cases; and type III (biphasic, six cases. Delayed increases in NAR were not observed in type I patients with weak responses to nasal challenge. In type II patients, baseline NAR was elevated and numerous basophilic metachromatic cells (BC were present in the epithelial layer. In type III patients, baseline NAR was not as elevated as it was in type II patients, but marked responses to challenge were noted. In all three types of changes in NAR, eosinophil leukocyte increased at late phase. Moreover, there was no correlation of change in NAR with an increase in the number of eosinophil leukocyte and BC at the epithelial layer in all three types, which suggests that further study is required to confirm the exact role of eosinophils and basophilic cells in LPR.
2T-PERIODIC SOLUTION FOR m ORDER NEUTRAL TYPE DIFFERENTIAL EQUATIONS WITH TIME DELAYS
Institute of Scientific and Technical Information of China (English)
张保生; 朱光辉
2002-01-01
Periodic solution of m order linear neutral equations with constant coefficient and time delays was studied. Existence and uniqueness of 2 T-periodic solutions for the equation were discussed by using the method of Fourier series. Some new necessary and sufficient conditions of existence and uniqueness of 2 T-periodic solutions for the equation are obtained. The main result is used widely. It contains results in some correlation paper for its special case, improves and extends the main results in them. Existence of periodic solution for the equation in larger number of particular case can be checked by using the result, but cannot be checked in another paper. In other words, the main result in this paper is most generalized for (1), the better result cannot be found by using the same method.
Wang, Xiao-Yen; Chow, Chuen-Yen; Chang, Sin-Chung
1996-01-01
The I-D, quasi I-D and 2-D Euler solvers based on the method of space-time conservation element and solution element are used to simulate various flow phenomena including shock waves, Mach stem, contact surface, expansion waves, and their intersections and reflections. Seven test problems are solved to demonstrate the capability of this method for handling unsteady compressible flows in various configurations. Numerical results so obtained are compared with exact solutions and/or numerical solutions obtained by schemes based on other established computational techniques. Comparisons show that the present Euler solvers can generate highly accurate numerical solutions to complex flow problems in a straightforward manner without using any ad hoc techniques in the scheme.
Novel insights on the stabilising solution to the continuous-time algebraic Riccati equation
Rojas, A. J.
2014-11-01
In the present paper we present a closed-form solution, as a function of the closed-loop poles, for the continuous-time algebraic Riccati equations (CAREs) related to single-input single-output systems with non-repeated poles. The proposed solution trades the standard numerical algorithm approach for one based on a spectral factorisation argument, offering potential insight into any control technique based on a CARE and its solution. As an example, we present the equivalence of two fairly recent control over network results. Furthermore we apply the proposed result to the formula for the optimal regulator gain matrix k (or equivalently the Luenberger's observer gain l) and present an example. Finally, we conclude by discussing the possible extension of the proposed closed-form solution to the repeated eigenvalues case and to the case when the CARE is related to multiple-input multiple-output systems.
Reducing Time for the Product Development Process by Evaluation in the Phase of Solution Searching
Directory of Open Access Journals (Sweden)
B. Jokele
2003-01-01
Full Text Available Less and less time is available for product development process. To prevent product failures and the resulting time intensive and cost intensive iteration steps, some preventive measures must be taken. Within the scope of quality management, FMEA anticipates possible problems concerning product and process properties. Nevertheless, in industrial practice designed products can have failures which were not considered within FMEA. The time pressure is immense, and efforts which do not make a contribution to a successful solution are regarded as lost time.This paper introduces a systematic approach to troubleshooting, with the aim of reducing the time for solution searching by considering the feasibility of ideas at an early stage.
New analytical exact solutions of time fractional KdV-KZK equation by Kudryashov methods
S Saha, Ray
2016-04-01
In this paper, new exact solutions of the time fractional KdV-Khokhlov-Zabolotskaya-Kuznetsov (KdV-KZK) equation are obtained by the classical Kudryashov method and modified Kudryashov method respectively. For this purpose, the modified Riemann-Liouville derivative is used to convert the nonlinear time fractional KdV-KZK equation into the nonlinear ordinary differential equation. In the present analysis, the classical Kudryashov method and modified Kudryashov method are both used successively to compute the analytical solutions of the time fractional KdV-KZK equation. As a result, new exact solutions involving the symmetrical Fibonacci function, hyperbolic function and exponential function are obtained for the first time. The methods under consideration are reliable and efficient, and can be used as an alternative to establish new exact solutions of different types of fractional differential equations arising from mathematical physics. The obtained results are exhibited graphically in order to demonstrate the efficiencies and applicabilities of these proposed methods of solving the nonlinear time fractional KdV-KZK equation.
Shi, Yifei
2013-08-01
Internal resonant modes are always observed in the marching-on-in-time (MOT) solution of the time domain electric field integral equation (EFIE), although \\'relaxed initial conditions,\\' which are enforced at the beginning of time marching, should in theory prevent these spurious modes from appearing. It has been conjectured that, numerical errors built up during time marching establish the necessary initial conditions and induce the internal resonant modes. However, this conjecture has never been proved by systematic numerical experiments. Our numerical results in this communication demonstrate that, the internal resonant modes\\' amplitudes are indeed dictated by the numerical errors. Additionally, it is shown that in a few cases, the internal resonant modes can be made \\'invisible\\' by significantly suppressing the numerical errors. These tests prove the conjecture that the internal resonant modes are induced by numerical errors when the time domain EFIE is solved by the MOT method. © 2013 IEEE.
Large time behavior for solutions of nonlinear parabolic problems with sign-changing measure data
Directory of Open Access Journals (Sweden)
Francesco Petitta
2008-09-01
Full Text Available Let $Omegasubseteq mathbb{R}^N$ a bounded open set, $Ngeq 2$, and let $p>1$; in this paper we study the asymptotic behavior with respect to the time variable $t$ of the entropy solution of nonlinear parabolic problems whose model is $$displaylines{ u_{t}(x,t-Delta_{p} u(x,t=mu quad hbox{in } Omegaimes(0,infty,cr u(x,0=u_{0}(x quad hbox{in } Omega, }$$ where $u_0 in L^{1}(Omega$, and $muin mathcal{M}_{0}(Q$ is a measure with bounded variation over $Q=Omegaimes(0,infty$ which does not charge the sets of zero $p$-capacity; moreover we consider $mu$ that does not depend on time. In particular, we prove that solutions of such problems converge to stationary solutions.
Li, Quan-Lin
2010-01-01
In this paper, we provide a novel matrix-analytic approach for studying doubly exponential solution of randomized load balancing models (also known as the supermarket models) with Markovian arrival processes (MAPs) and PH service times. We describe the supermarket model as a system of differential vector equations, and obtain a close-form solution: doubly exponential structure, for the fixed point of the system of differential vector equations. Based on this, we show that the fixed point is decomposited into two groups of information under a product form: the arrival information and the service information, and indicate that the doubly exponential solution to the fixed point is not always unique for more general supermarket models. Furthermore, we analyze the exponential convergence of the current location of the supermarket model to its fixed point, and study the Lipschitz condition in the Kurtz Theorem under MAP arrivals and PH service times. This paper gains a new understanding how the workload probing can...
Mlpnp - a Real-Time Maximum Likelihood Solution to the Perspective-N Problem
Urban, S.; Leitloff, J.; Hinz, S.
2016-06-01
In this paper, a statistically optimal solution to the Perspective-n-Point (PnP) problem is presented. Many solutions to the PnP problem are geometrically optimal, but do not consider the uncertainties of the observations. In addition, it would be desirable to have an internal estimation of the accuracy of the estimated rotation and translation parameters of the camera pose. Thus, we propose a novel maximum likelihood solution to the PnP problem, that incorporates image observation uncertainties and remains real-time capable at the same time. Further, the presented method is general, as is works with 3D direction vectors instead of 2D image points and is thus able to cope with arbitrary central camera models. This is achieved by projecting (and thus reducing) the covariance matrices of the observations to the corresponding vector tangent space.
Rödig, C; Chizhov, I; Weidlich, O; Siebert, F
1999-01-01
In this report, from time-resolved step-scan Fourier transform infrared investigations from 15 ns to 160 ms, we provide evidence for the subsequent rise of three different M states that differ in their structures. The first state rises with approximately 3 microseconds to only a small percentage. Its structure as judged from amide I/II bands differs in small but well-defined aspects from the L state. The next M state, which appears in approximately 40 microseconds, has almost all of the characteristics of the "late" M state, i.e., it differs considerably from the first one. Here, the L left arrow over right arrow M equilibrium is shifted toward M, although some percentage of L still persists. In the last M state (rise time approximately 130 microseconds), the equilibrium is shifted toward full deprotonation of the Schiff base, and only small additional structural changes take place. In addition to these results obtained for unbuffered conditions or at pH 7, experiments performed at lower and higher pH are presented. These results are discussed in terms of the molecular changes postulated to occur in the M intermediate to allow the shift of the L/M equilibrium toward M and possibly to regulate the change of the accessibility of the Schiff base necessary for effective proton pumping. PMID:10233083
Directory of Open Access Journals (Sweden)
Omprakash Kaiwartya
2015-01-01
Full Text Available A multiobjective dynamic vehicle routing problem (M-DVRP has been identified and a time seed based solution using particle swarm optimization (TS-PSO for M-DVRP has been proposed. M-DVRP considers five objectives, namely, geographical ranking of the request, customer ranking, service time, expected reachability time, and satisfaction level of the customers. The multiobjective function of M-DVRP has four components, namely, number of vehicles, expected reachability time, and profit and satisfaction level. Three constraints of the objective function are vehicle, capacity, and reachability. In TS-PSO, first of all, the problem is partitioned into smaller size DVRPs. Secondly, the time horizon of each smaller size DVRP is divided into time seeds and the problem is solved in each time seed using particle swarm optimization. The proposed solution has been simulated in ns-2 considering real road network of New Delhi, India, and results are compared with those obtained from genetic algorithm (GA simulations. The comparison confirms that TS-PSO optimizes the multiobjective function of the identified problem better than what is offered by GA solution.
Stein, H. J.; Zimmerman, A.; Hannah, J. L.; Markey, R. J.
2003-04-01
Eight Re-Os ages from six molybdenite samples representative of Cu-Mo mineralization in a highly deformed quartz reef and granite host rock comprising the large Malanjkhand deposit were obtained using ID-NTIMS. These data provide a clear Late Archean-Early Proterozoic age for this recently discovered deposit and by implication a minimum age for its hosting terrane, the Central Indian Tectonic Zone (CITZ), a continental scale structure separating peninsular India from northern India. The CITZ was previously inferred to be Middle Proterozoic or younger. Molybdenite dating indicates that stringer mineralization in the quartz reef and disseminated mineralization in the granite were contemporaneous at 2493 ± 8 Ma (2493.1 ± 1.4 Ma based on regression without uncertainty in the 187Re decay constant, MSWD = 0.5, n = 5). Additional molybdenite was precipitated during at least two pulses of reworking (ěrb1 12480 and ěrb1 12450 Ma) that we suggest configured the elongate quartz reef as the CITZ developed in response to NW-directed oblique convergence of a landmass from the south. Previously unrecognized petrographic evidence coupled with high Re concentrations for molybdenites (400-650 ppm) suggest that Malanjkhand is a porphyry Cu-Mo deposit of classic Andean-type, forming in a subduction-accretionary setting that includes involvement of mantle. We suggest that the CITZ may provide a median segment of an extensive and continuous Late Archean-Early Proterozoic orogenic belt that may include portions of the Moyar, Bhavani, Palghat, and Cauvery shear zones in southern India, the Eastern Ghats orogenic belt along the eastern side of India, and connecting to the Aravalli-Delhi belt extending through northwest India. This now folded orogenic belt could be related to the assembly of a Late Archean supercontinent whose eastward margin included East Antartica (Napier complex) at 2.5 Ga. In addition, we suggest that the Vestfold Hills complex (East Antartica) was part of this
Directory of Open Access Journals (Sweden)
Koonin Eugene V
2006-08-01
Full Text Available Abstract Background Ever since the discovery of 'genes in pieces' and mRNA splicing in eukaryotes, origin and evolution of spliceosomal introns have been considered within the conceptual framework of the 'introns early' versus 'introns late' debate. The 'introns early' hypothesis, which is closely linked to the so-called exon theory of gene evolution, posits that protein-coding genes were interrupted by numerous introns even at the earliest stages of life's evolution and that introns played a major role in the origin of proteins by facilitating recombination of sequences coding for small protein/peptide modules. Under this scenario, the absence of spliceosomal introns in prokaryotes is considered to be a result of "genome streamlining". The 'introns late' hypothesis counters that spliceosomal introns emerged only in eukaryotes, and moreover, have been inserted into protein-coding genes continuously throughout the evolution of eukaryotes. Beyond the formal dilemma, the more substantial side of this debate has to do with possible roles of introns in the evolution of eukaryotes. Results I argue that several lines of evidence now suggest a coherent solution to the introns-early versus introns-late debate, and the emerging picture of intron evolution integrates aspects of both views although, formally, there seems to be no support for the original version of introns-early. Firstly, there is growing evidence that spliceosomal introns evolved from group II self-splicing introns which are present, usually, in small numbers, in many bacteria, and probably, moved into the evolving eukaryotic genome from the α-proteobacterial progenitor of the mitochondria. Secondly, the concept of a primordial pool of 'virus-like' genetic elements implies that self-splicing introns are among the most ancient genetic entities. Thirdly, reconstructions of the ancestral state of eukaryotic genes suggest that the last common ancestor of extant eukaryotes had an intron
Directory of Open Access Journals (Sweden)
Emad A-B. Abdel-Salam
2015-06-01
Full Text Available In this paper, the improved fractional Riccati expansion method is proposed to solve fractional differential equations. The method is applied to solve space–time fractional modified Korteweg–de Vries equation, space–time fractional modified regularized long-wave equation, time fractional biological population model, and space–time fractional Klein–Gordon equation. The obtained solutions include generalized trigonometric and hyperbolic functions solutions. Among these solutions, some are found for the first time.
Exact solutions to the supply chain equations for arbitrary, time-dependent demands
DEFF Research Database (Denmark)
Warburton, Roger D.H.; Hodgson, J.P.E.; Nielsen, Erland Hejn
2014-01-01
We study the impact on inventory of an unexpected, non-linear, time-dependent demand and present the exact solutions over time to the supply chain equations without requiring any approximations. We begin by imposing a boundary condition of stability at infinity, from which we derive expressions...... for the estimated demand and the target work in progress when the demand is time-dependent. The resulting inventory equation is solved in terms of the Lambert modes with all of the demand non-linearities confined to the pre-shape function. The series solution is exact, and all terms are reasonably easy to calculate......, so users can determine the inventory behavior to any desired precision. To illustrate, we solve the equations for a non-linear, quadratic time-dependence in the demand. For practical use, only a few terms in the series are required, a proposition illustrated by the For All Practical Purposes (FAPP...
Exact solutions to the supply chain equations for arbitrary, time-dependent demands
DEFF Research Database (Denmark)
Warburton, Roger D.H.; Hodgson, J.P.E.; Nielsen, Erland Hejn
2014-01-01
, so users can determine the inventory behavior to any desired precision. To illustrate, we solve the equations for a non-linear, quadratic time-dependence in the demand. For practical use, only a few terms in the series are required, a proposition illustrated by the For All Practical Purposes (FAPP......We study the impact on inventory of an unexpected, non-linear, time-dependent demand and present the exact solutions over time to the supply chain equations without requiring any approximations. We begin by imposing a boundary condition of stability at infinity, from which we derive expressions...... for the estimated demand and the target work in progress when the demand is time-dependent. The resulting inventory equation is solved in terms of the Lambert modes with all of the demand non-linearities confined to the pre-shape function. The series solution is exact, and all terms are reasonably easy to calculate...
Lie Group Classifications and Non-differentiable Solutions for Time-Fractional Burgers Equation
Institute of Scientific and Technical Information of China (English)
WU Guo-Cheng
2011-01-01
Lie group method provides an efficient tool to solve nonlinear partial differential equations.This paper suggests Lie group method for fractional partial differential equations.A time-fractional Burgers equation is used as an example to illustrate the effectiveness of the Lie group method and some classes of exact solutions are obtained.
Periodic Solutions for a Class of Singular Hamiltonian Systems on Time Scales
Directory of Open Access Journals (Sweden)
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.
Exact solutions to three-dimensional time-dependent Schrödinger equation
Indian Academy of Sciences (India)
Fakir Chand; S C Mishra
2007-06-01
With a view to obtain exact analytic solutions to the time-dependent Schrödinger equation for a few potentials of physical interest in three dimensions, transformation-group method is used. Interestingly, the integrals of motion in the new coordinates turn out to be the desired invariants of the systems.
Almost Periodic Solutions to Dynamic Equations on Time Scales and Applications
Directory of Open Access Journals (Sweden)
Yongkun Li
2012-01-01
equations on time scales. Then, as an application, using these concepts and results, we establish sufficient conditions for the existence and exponential stability of almost periodic solution to a class of Hopfield neural networks with delays. Finally, two examples and numerical simulations given to illustrate our results are plausible and meaningful.
Generalized Nehari functionals and finite time blow up of the solutions to Boussinesq equation
Kolkovska, N.; Dimova, M.; Kutev, N.
2015-10-01
We study the Cauchy problem to generalized Boussinesq equation with linear restoring force and combined power type nonlinearities. Generalized Nehari functionals are introduced and their monotonicity and sign preserving properties are established. By means of an extension of the concavity method of Levine and generalized Nehari functionals finite time blow up of the solutions with arbitrary high positive initial energy is proved.
Stability and attractivity of solutions of differential equations with impulses at fixed times
Directory of Open Access Journals (Sweden)
S. Sivasundaram
2000-01-01
Full Text Available In this paper we consider the dynamics of solutions of impulsive differential equations with fixed time moments of impulsive effects on the basis of comparison methods and vector Lyapunov functions. We propose sufficient conditions on the following dynamic properties: stability, attractivity, and some combinations of them.
Almost periodic solution of shunting inhibitory cellular neural networks with time-varying delay
Energy Technology Data Exchange (ETDEWEB)
Huang Xia; Cao Jinde
2003-07-28
Several sufficient conditions are obtained for the existence of almost periodic solution and its attractivity of shunting inhibitory cellular neural networks with time-varying delay based on the fixed point method and Halanay inequality technique. Some previous results are improved and extended in this Letter and two examples are given to illustrate the effectiveness of the new results.
Periodic Solution to BAM-type Cohen-Grossberg Neural Network with Time-varying Delays
Institute of Scientific and Technical Information of China (English)
An-ping Chen; Qun-hua Gu
2011-01-01
By using the continuation theorem of Mawhin's coincidence degree theory and the Liapunov functional method, some sufficient conditions are obtained to ensure the existence, uniqueness and the global exponential stability of the periodic solution to the BAM-type Cohen-Grossberg neural networks involving time-varying delays.
Directory of Open Access Journals (Sweden)
Xinggui Liu
2011-01-01
Full Text Available In this paper, by using Mawhin's continuation theorem of coincidence degree theory, we establish the existence of at least four positive periodic solutions for a discrete time Lotka-Volterra competitive system with harvesting terms. An example is given to illustrate the effectiveness of our results.
POSITIVE SOLUTIONS FOR p-LAPLACIAN DYNAMIC EQUATIONS ON TIME SCALES
Institute of Scientific and Technical Information of China (English)
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.
GLOBAL SOLUTIONS AND FINITE TIME BLOW UP FOR DAMPED KLEIN-GORDON EQUATION
Institute of Scientific and Technical Information of China (English)
Runzhang XU; Yunhua DING
2013-01-01
We study the Cauchy problem of strongly damped Klein-Gordon equation.Global existence and asymptotic behavior of solutions with initial data in the potential well are derived.Moreover,not only does finite time blow up with initial data in the unstable set is proved,but also blow up results with arbitrary positive initial energy are obtained.
Existence of Solutions for Nonlinear Four-Point -Laplacian Boundary Value Problems on Time Scales
Directory of Open Access Journals (Sweden)
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.
Energy Technology Data Exchange (ETDEWEB)
Sun Wen [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China); Chen Shihua [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China)]. E-mail: shcheng@whu.edu.cn; Hong Zhiming [School of Mathematics and Statistics, Wuhan University, Wuhan 430072 (China); Wang Changping [Department of Mathematics and Statistics, Dalhousie University, Halifax, NS, B3H 3J5 (Canada)
2007-08-15
A two-species periodic competition Lotka-Volterra system with time delay and diffusion is investigated. Some sufficient conditions of the existence of positive periodic solution are established for the system by using the continuation theorem of coincidence degree theory.
The comparison of OPC performance and run time for dense versus sparse solutions
Abdo, Amr; Stobert, Ian; Viswanathan, Ramya; Burns, Ryan; Herold, Klaus; Kallingal, Chidam; Meiring, Jason; Oberschmidt, James; Mansfield, Scott
2008-03-01
The lithographic processes and resolution enhancement techniques (RET) needed to achieve pattern fidelity are becoming more complicated as the required critical dimensions (CDs) shrink. For technology nodes with smaller devices and tolerances, more complex models and proximity corrections are needed and these significantly increase the computational requirements. New simulation techniques are required to address these computational challenges. The new simulation technique we focus on in this work is dense optical proximity correction (OPC). Sparse OPC tools typically require a laborious, manual and time consuming OPC optimization approach. In contrast, dense OPC uses pixel-based simulation that does not need as much manual setup. Dense OPC was introduced because sparse simulation methodology causes run times to explode as the pattern density increases, since the number of simulation sites in a given optical radius increases. In this work, we completed a comparison of the OPC modeling performance and run time for the dense and the sparse solutions. The analysis found the computational run time to be highly design dependant. The result should lead to the improvement of the quality and performance of the OPC solution and shed light on the pros and cons of using dense versus sparse solution. This will help OPC engineers to decide which solution to apply to their particular situation.
Lie symmetry analysis and soliton solutions of time-fractional $K(m, n)$ equation
Indian Academy of Sciences (India)
G W WANG; M S HASHEMI
2017-01-01
In this note, method of Lie symmetries is applied to investigate symmetry properties of timefractional $K(m, n)$ equation with the Riemann–Liouville derivatives. Reduction of time-fractional $K(m, n)$ equation is done by virtue of the Erdélyi–Kober fractional derivative which depends on a parameter α. Thensoliton solutions are extracted by means of a transformation.
A note on the time decay of solutions for the linearized Wigner-Poisson system
Gamba, Irene
2009-01-01
We consider the one-dimensional Wigner-Poisson system of plasma physics, linearized around a (spatially homogeneous) Lorentzian distribution and prove that the solution of the corresponding linearized problem decays to zero in time. We also give an explicit algebraic decay rate.
Interpolating solution from AdS$_5$ to hyperscaling violating Lifshitz space-time
Dey, Parijat
2014-01-01
We construct two interpolating solutions in type II string theory which interpolate between an AdS$_5$ in the UV and a hyperscaling violating three (spatial) dimensional Lifshitz space-time in the IR. The first solution is non-supersymmetric and is obtained from a known intersecting non-supersymmetric D3-brane with chargeless D0-brane solution of type IIB string theory, by restricting some parameters characterizing the solution and going to a new coordinate. In the IR the dilaton is non-constant in general and the metric is three (spatial) dimensional hyperscaling violating Lifshitz with dynamical critical exponent $z=(3+3\\gamma)/(3-\\gamma)$ and hyperscaling violation exponent $\\theta = 12/(3-\\gamma)$, where $\\gamma$ is a real parameter and can take continuous values from $-1$ to $+1$. At the two extreme values, i.e., for $\\gamma = \\pm 1$, the dilaton is constant. The second solution is supersymmetric and is obtained from the known F-D2 bound state solution of type IIA string theory by zooming into a particul...
Energy Technology Data Exchange (ETDEWEB)
Wang, Hailing [Institute of Applied Mathematics, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Department of Mathematics, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong); Chung, Kwok-wai, E-mail: makchung@cityu.edu.hk [Department of Mathematics, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)
2012-02-27
The analytical solutions of nonlinear oscillators obtained from most perturbation or approximate methods usually have poor accuracy near homoclinic/heteroclinic (HH) orbits. In this Letter, we propose a nonlinear time transformation method to overcome such difficulty. In particular, we apply such method with Padé approximation to find analytical solutions of a generalized Duffing-harmonic oscillator having a rational form for the potential energy. For some parametric ranges, HH orbits exist in such an oscillator. For analytical approximation of periodic solution obtained from the present method, it is shown that the relative error of period with respect to the exact period tends to zero when the amplitude of periodic solution tends to either zero or infinity. The relative error is still very small even near to HH orbits. Furthermore, analytical approximate of HH orbits can also be obtained. From the illustrative examples, the phase portraits are in excellent agreement with the exact HH orbits. The results from the present method are compared with the exact solutions and that from the cubication method. -- Highlights: ► A nonlinear transformation is proposed for a generalized Duffing-harmonic oscillator. ► The relative error of period with respect to the exact one is always very small. ► Approximate solution of homoclinic/heteroclinic orbits can be obtained. ► Phase portraits are in excellent agreement even at homoclinic/heteroclinic orbits.
Analytical Solutions of Time Periodic Electroosmotic Flow in a Semicircular Microchannel
Directory of Open Access Journals (Sweden)
Shaowei Wang
2015-01-01
Full Text Available The time periodic electroosmotic flow of Newtonian fluids through a semicircular microchannel is studied under the Debye–Hückel approximation. Analytical series of solutions are found, and they consist of a time-dependent oscillating part and a time-dependent generating or transient part. Some new physical phenomena are found. The electroosmotic flow driven by an alternating electric field is not periodic in time, but quasi-periodic. There is a phase shift between voltage and flow, which is only dependent on the frequency of external electric field.
Rudenko, Sergei; Gruber, Christian
2016-04-01
This study makes use of current GFZ monthly and daily gravity field products from 2002 to 2014 based on radial basis functions (RBF) instead of time variable gravity field modeling for precise orbit determination of altimetry satellites. Since some monthly solutions are missing in the GFZ GRACE RL05a solution and in order to reach a better quality for the precise orbit determination, daily generated RBF solutions obtained from Kalman filtered GRACE data processing and interpolated in case of gaps have been used. Moreover, since the geopotential coefficients of low degrees are better determined using SLR observations to geodetic satellites like Lageos, Stella, Starlette and Ajisai than from GRACE observations, these terms are co-estimated in the RBF solutions by using apriori SLR-derived values up to degree and order 4. Precise orbits for altimetry satellites Envisat (2002-2012), Jason-1 (2002-2013) and Jason-2 (2008-2014) are then computed over the given time intervals using this approach and compared with the orbits obtained when using other models such as EIGEN-6S4. An analysis of the root-mean-square values of the observation fits of SLR and DORIS observations and the orbit arcs overlaps will allow us to draw a conclusion on the quality of the RBF solution and to use these new trajectories for sea level trend estimates and geophysical application.
GRACE RL03-v2 monthly time series of solutions from CNES/GRGS
Lemoine, Jean-Michel; Bourgogne, Stéphane; Bruinsma, Sean; Gégout, Pascal; Reinquin, Franck; Biancale, Richard
2015-04-01
Based on GRACE GPS and KBR Level-1B.v2 data, as well as on LAGEOS-1/2 SLR data, CNES/GRGS has published in 2014 the third full re-iteration of its GRACE gravity field solutions. This monthly time series of solutions, named RL03-v1, complete to spherical harmonics degree/order 80, has displayed interesting performances in terms of spatial resolution and signal amplitude compared to JPL/GFZ/CSR RL05. This is due to a careful selection of the background models (FES2014 ocean tides, ECMWF ERA-interim (atmosphere) and TUGO (non IB-ocean) "dealiasing" models every 3 hours) and to the choice of an original method for gravity field inversion : truncated SVD. Identically to the previous CNES/GRGS releases, no additional filtering of the solutions is necessary before using them. Some problems have however been identified in CNES/GRGS RL03-v1: - an erroneous mass signal located in two small circular rings close to the Earth's poles, leading to the recommendation not to use RL03-v1 above 82° latitudes North and South; - a weakness in the sectorials due to an excessive downweighting of the GRACE GPS observations. These two problems have been understood and addressed, leading to the computation of a corrected time series of solutions, RL03-v2. The corrective steps have been: - to strengthen the determination of the very low degrees by adding Starlette and Stella SLR data to the normal equations; - to increase the weight of the GRACE GPS observations; - to adopt a two steps approach for the computation of the solutions: first a Choleski inversion for the low degrees, followed by a truncated SVD solution. The identification of these problems will be discussed and the performance of the new time series evaluated.
Large-time behavior of solutions to a thermo-diffusion system with Smoluchowski interactions
Aiki, Toyohiko; Muntean, Adrian
2017-09-01
We prove the large time behavior of solutions to a coupled thermo-diffusion arising in the modeling of the motion of hot colloidal particles in porous media. Additionally, we also ensure the uniqueness of solutions of the target problem. The main mathematical difficulty is due to the presence in the right-hand side of the equations of products between temperature and concentration gradients. Such terms mimic the so-called thermodynamic Soret and Dufour effects. These are cross-coupling terms emphasizing in this context a strong interplay between heat conduction and molecular diffusion.
Seidi, M.; Behnia, S.; Khodabakhsh, R.
2014-09-01
Point reactor kinetics equations with one group of delayed neutrons in the presence of the time-dependent external neutron source are solved analytically during the start-up of a nuclear reactor. Our model incorporates the random nature of the source and linear reactivity variation. We establish a general relationship between the expectation values of source intensity and the expectation values of neutron density of the sub-critical reactor by ignoring the term of the second derivative for neutron density in neutron point kinetics equations. The results of the analytical solution are in good agreement with the results obtained with numerical solution.
Directory of Open Access Journals (Sweden)
J. Rodrigues Dias
2006-11-01
Full Text Available Systems with different lifetime distributions, associated with increasing, decreasing, constant, and bathtub-shaped hazard rates, are examined in this paper. It is assumed that a failure is only detected if systems are inspected. New approximate solutions for the inspection period and for the expected duration of hidden faults are presented, on the basis of the assumption that only periodic and perfect inspections are carried out. By minimizing total expected cost per unit of time, on the basis of numerical results and a range of comparisons, the conclusion is drawn that these new approximate solutions are extremely useful and simple to put into practice.
Protopopescu, V; Barhen, J
2003-01-01
A constant-time solution of the continuous global optimization problem (GOP) is obtained by using an ensemble algorithm. We show that under certain assumptions, the solution can be guaranteed by mapping the GOP onto a discrete unsorted search problem, whereupon Brueschweiler's ensemble search algorithm is applied. For adequate sensitivities of the measurement technique, the query complexity of the ensemble search algorithm depends linearly on the size of the function's domain. Advantages and limitations of an eventual NMR implementation are discussed. (letter to the editor)
Bosch, Jessica
2014-04-01
We consider the efficient solution of the Cahn-Hilliard variational inequality using an implicit time discretization, which is formulated as an optimal control problem with pointwise constraints on the control. By applying a semi-smooth Newton method combined with a Moreau-Yosida regularization technique for handling the control constraints we show superlinear convergence in function space. At the heart of this method lies the solution of large and sparse linear systems for which we propose the use of preconditioned Krylov subspace solvers using an effective Schur complement approximation. Numerical results illustrate the competitiveness of this approach. © 2014 Elsevier Inc.
Topological and non-topological soliton solutions to some time-fractional differential equations
Indian Academy of Sciences (India)
M Mirzazadeh
2015-07-01
This paper investigates, for the first time, the applicability and effectiveness of He’s semi-inverse variational principle method and the ansatz method on systems of nonlinear fractional partial differential equations. He’s semi-inverse variational principle method and the ansatz method are used to construct exact solutions of nonlinear fractional Klein–Gordon equation and generalized Hirota–Satsuma coupled KdV system. These equations have been widely applied in many branches of nonlinear sciences such as nonlinear optics, plasma physics, superconductivity and quantum mechanics. So, finding exact solutions of such equations are very helpful in the theoretical and numerical studies.
Exponential stability of solutions to nonlinear time-delay systems of neutral type
Directory of Open Access Journals (Sweden)
Gennadii V. Demidenko
2016-01-01
Full Text Available We consider a nonlinear time-delay system of neutral equations with constant coefficients in the linear terms $$ \\frac{d}{dt}\\big(y(t + D y(t-\\tau\\big = A y(t + B y(t-\\tau + F(t, y(t, y(t-\\tau, $$ where $$ \\|F(t,u,v\\| \\le q_1\\|u\\|^{1+\\omega_1} + q_2\\|v\\|^{1+\\omega_2}, \\quad q_1, q_2, \\omega_1, \\omega_2 > 0. $$ We obtain estimates characterizing the exponential decay of solutions at infinity and estimates for attraction sets of the zero solution.
Large Time Behavior for Weak Solutions of the 3D Globally Modified Navier-Stokes Equations
Directory of Open Access Journals (Sweden)
Junbai Ren
2014-01-01
Full Text Available This paper is concerned with the large time behavior of the weak solutions for three-dimensional globally modified Navier-Stokes equations. With the aid of energy methods and auxiliary decay estimates together with Lp-Lq estimates of heat semigroup, we derive the optimal upper and lower decay estimates of the weak solutions for the globally modified Navier-Stokes equations as C1(1+t-3/4≤uL2≤C2(1+t-3/4, t>1. The decay rate is optimal since it coincides with that of heat equation.
Comments on multiple oscillatory solutions in systems with time-delay feedback
Directory of Open Access Journals (Sweden)
Michael Stich
2015-11-01
Full Text Available A complex Ginzburg-Landau equation subjected to local and global time-delay feedback terms is considered. In particular, multiple oscillatory solutions and their properties are studied. We present novel results regarding the disappearance of limit cycle solutions, derive analytical criteria for frequency degeneration, amplitude degeneration, and frequency extrema. Furthermore, we discuss the influence of the phase shift parameter and show analytically that the stabilization of the steady state and the decay of all oscillations (amplitude death cannot happen for global feedback only. Finally, we explain the onset of traveling wave patterns close to the regime of amplitude death.
Kalman Filtered Daily GRACE Gravity Field Solutions in Near Real-Time- First Steps
Kvas, Andreas; Mayer-Gurr, Torsten
2016-08-01
As part of the EGSIEM (European Gravity Service for Improved Emergency Management) project, a technology demonstrator for a near real-time (NRT) gravity field service will be established. In preparation of the operational phase, several aspects of the daily gravity field processing chain at Graz University of Technology have been inspected in order to improve the gravity field solutions and move towards NRT. The effect of these adaptions is investigated by comparison with post-processing and forward-only filtered solutions and evaluated using in-situ data.
ASYMPTOTIC PROPERTY OF THE TIME-DEPENDENT SOLUTION OF A RELIABILITY MODEL
Institute of Scientific and Technical Information of China (English)
Geni Gupur; GUO Baozhu
2005-01-01
We discuss a transfer line consisting of a reliable machine, an unreliable machine and a storage buffer. This transfer line can be described by a group of partial differential equations with integral boundary conditions. First we show that the operator corresponding to these equations generates a positive contraction C0-semigroup T(t), and prove that T(t) is a quasi-compact operator. Next we verify that 0 is an eigenvalue of this operator and its adjoint operator with geometric multiplicity one. Last, by using the above results we obtain that the time-dependent solution of these equations converges strongly to their steady-state solution.
Stabilizing Solution for a Discrete-Time Modified Algebraic Riccati Equation in Infinite Dimensions
Directory of Open Access Journals (Sweden)
Viorica Mariela Ungureanu
2015-01-01
Full Text Available We provide necessary and sufficient conditions for the existence of stabilizing solutions for a class of modified algebraic discrete-time Riccati equations (MAREs defined on ordered Banach spaces of sequences of linear and bounded operators. These MAREs arise in the study of linear quadratic (LQ optimal control problems for infinite-dimensional discrete-time linear systems (DTLSs affected simultaneously by multiplicative white noise (MN and Markovian jumps (MJs. Unlike most of the previous works, where the detectability and observability notions are key tools for studying the global solvability of MAREs, in this paper the conditions of existence of mean-square stabilizing solutions are given directly in terms of system parameters. The methods we have used are based on the spectral theory of positive operators and the properties of trace class and compact operators. Our results generalise similar ones obtained for finite-dimensional MAREs associated with stochastic DTLSs without MJs. Also they complete and extend (in the autonomous case former investigations concerning the existence of certain global solutions (as minimal, maximal, and stabilizing solutions for generalized discrete-time Riccati type equations defined on infinite-dimensional ordered Banach spaces.
Saxena, R. K.; Mathai, A. M.; Haubold, H. J.
2015-10-01
This paper deals with the investigation of the computational solutions of an unified fractional reaction-diffusion equation, which is obtained from the standard diffusion equation by replacing the time derivative of first order by the generalized fractional time-derivative defined by Hilfer (2000), the space derivative of second order by the Riesz-Feller fractional derivative and adding the function ϕ (x, t) which is a nonlinear function governing reaction. The solution is derived by the application of the Laplace and Fourier transforms in a compact and closed form in terms of the H-function. The main result obtained in this paper provides an elegant extension of the fundamental solution for the space-time fractional diffusion equation obtained earlier by Mainardi et al. (2001, 2005) and a result very recently given by Tomovski et al. (2011). Computational representation of the fundamental solution is also obtained explicitly. Fractional order moments of the distribution are deduced. At the end, mild extensions of the derived results associated with a finite number of Riesz-Feller space fractional derivatives are also discussed.
Head, James
2017-04-01
Formation of Late Noachian-Early Hesperian (LN-EH) valley network systems (VNS) signaled the presence of warm/wet conditions generating several hypotheses for climates permissive of these conditions. To constrain options for the ambient Noachian climate, we examine estimates for time required to carve channels/deltas and total duration implied by plausible intermittencies. Formation Times for VN, OBL, Deltas, Fans: A synthesis of required timescales show that even with the longest estimated continuous duration of VN formation/intermittencies, total time to carve the VN does not exceed 106 years, 273 K, hydrological system vertically integrated, and rainfall occurs to recharge the aquifer. Two subtypes: a) "Rainfall/Fluvial Erosion-Dominated Warm and Wet Model": "Rainfall and surface runoff" persist throughout Noachian to explain crater degradation, and a LN-EH short rapidly ending terminal epoch. b) "Recharge Evaporation/Evaporite Dominated Warm and Wet Model": Sustained period of equatorial/mid-latitude precipitation and a vertically integrated hydrological system driven by evaporative upwelling and fluctuating shallow water table playa environments account for sulfate evaporate environments at Meridiani Planum. Sustained temperatures >273 K are required for extended periods (107-108 years). 2) Cold and icy climate: Sustained background temperatures extremely low (MAT ˜225 K), cryosphere is globally continuous, hydrological system is horizontally stratified, separating groundwater system from surface; no combination of spin-axis/orbital perturbations can raise MAT to 273 K. Adiabatic cooling effects transfer water to high altitudes, leading to "Late Noachian Icy Highlands Model". VNS cannot form in this nominal climate environment without special circumstances (e.g., impacts or volcanic eruptions elevate of temperatures by >˜50 K to induce melting and fluvial/lacustrine activity). 3) Cold and Icy climate warmed by greenhouse gases: The climate is sustained cold
Directory of Open Access Journals (Sweden)
Henry F. Duncan
2015-09-01
Full Text Available Dental pulp tissue can be damaged by a range of irritants, however, if the irritation is removed and/or the tooth is adequately restored, pulp regeneration is possible (Mjör and Tronstad, 1974 [1]. At present, dental restorative materials limit healing by impairing mineralization and repair processes and as a result new biologically-based materials are being developed (Ferracane et al., 2010 [2]. Previous studies have highlighted the benefit of epigenetic modification by histone deacetylase inhibitor (HDACi application to dental pulp cells (DPCs, which induces changes to chromatin architecture, promoting gene expression and cellular-reparative events (Duncan et al., 2013 [3]; Paino et al., 2014 [4]. In this study a genome-wide transcription profiling in epigenetically-modified mineralizing primary DPC cultures was performed, at relatively early and late time-points, to identify differentially regulated transcripts that may provide novel therapeutic targets for use in restorative dentistry. Here we provide detailed methods and analysis on these microarray data which has been deposited in Gene Expression Omnibus (GEO: GSE67175.
Palencia-Ortas, A.; Osete, M. L.; Campuzano, S. A.; McIntosh, G.; Larrazabal, J.; Sastre, J.; Rodriguez-Aranda, J.
2017-09-01
This study presents new archaeomagnetic results from 33 combustion structures (kilns and hearths) from the archaeological sites of Castelinho, Crestelos, Olival Poço da Barca and Fonte do Milho in NE Portugal. The age of the investigated structures ranges from 1210 BC to 200 AD according to calibrated radiocarbon dating, thermoluminescence dating and archaeological constraints. Stepwise thermal and alternating field demagnetization isolate a single, stable, characteristic remanence component with very well defined directions. Rock magnetic analyses suggest low-Ti titanomagnetite/maghemite as the main magnetic carrier of the remanence. Mean directions are well grouped in most structures. The effect of thermoremanent anisotropy on mean directions has been evaluated and was found to be important. Inclination increases of between 2° and 13° after applying the anisotropy correction at specimen level. This highlights the requirement of evaluating this effect on the directions of small and flattened thin kilns and hearths. The 31 new directional data improve both the temporal and spatial distribution of the Iberian archaeomagnetic dataset from Late Bronze Age to Roman Times. Finally, a new directional palaeosecular variation curve for Iberia for the last twelve centuries BC is proposed. The curve has been computed using the bootstrap method and includes data coming from sites within 900 km of Madrid. The new palaeodirectional secular variation curve for Iberia is consistent with the Western European palaeosecular variation curve and with the prediction of regional European models.
A Multiwavelength Study of the Relativistic Tidal Disruption Candidate Sw J2058+05 at Late Times
Pasham, Dheeraj R; Levan, Andrew J; Bower, Geoffrey C; Horesh, Assaf; Brown, Gregory C; Dolan, Stephen; Wiersema, Klaas; Filippenko, Alexei V; Fruchter, Andrew S; Greiner, Jochen; Hounsell, Rebekah A; O'Brien, Paul T; Page, Kim L; Rau, Arne; Tanvir, Nial R
2015-01-01
${\\it Swift}$ J2058.4+0516 (Sw J2058+05, hereafter) has been suggested as the second member (after Sw J1644+57) of the rare class of tidal disruption events accompanied by relativistic ejecta. Here we report a multiwavelength (X-ray, ultraviolet/optical/infrared, radio) analysis of Sw J2058+05 from 3 months to 3 yr post-discovery in order to study its properties and compare its behavior with that of Sw J1644+57. Our main results are as follows. (1) The long-term X-ray light curve of Sw J2058+05 shows a remarkably similar trend to that of Sw J1644+57. After a prolonged power-law decay, the X-ray flux drops off rapidly by a factor of $\\gtrsim 160$ within a span of $\\Delta$$t$/$t$ $\\le$ 0.95. Associating this sudden decline with the transition from super-Eddington to sub-Eddington accretion, we estimate the black hole mass to be in the range of $10^{4-6}$ M$_{\\odot}$. (2) We detect rapid ($\\lesssim 500$ s) X-ray variability before the dropoff, suggesting that, even at late times, the X-rays originate from close ...
Thigpen, Nina N; Keil, Andreas; Freund, Alexandra M
2016-12-06
Processing the motivational relevance of a visual scene and reacting accordingly is crucial for survival. Previous work suggests the emotional content of naturalistic scenes affects response speed, such that unpleasant content slows responses whereas pleasant content accelerates responses. It is unclear whether these effects reflect motor-cognitive processes, such as attentional orienting, or vary with the function/outcome of the motor response itself. Four experiments manipulated participants' ability to terminate the picture (offset control) and, thereby, the response's function and motivational value. Attentive orienting was manipulated via picture repetition, which diminishes orienting. A total of N = 81 participants completed versions of a go/no-go task, discriminating between distorted versus intact pictures drawn from six content categories varying in positive, negative, or neutral valence. While all participants responded faster with repetition, only participants without offset control exhibited slower responses to unpleasant and accelerated responses to pleasant content. Emotional engagement, measured by the late positive potential, was not modulated by attentional orienting (repetition), suggesting that the interaction between repetition and offset control is not due to altered emotional engagement. Together, results suggest that response time changes as a function of emotional content and sensitivity to attention orienting depends on the motivational function of the motor response.
Goličnik, Marko
2011-04-15
Various explicit reformulations of time-dependent solutions for the classical two-step irreversible Michaelis-Menten enzyme reaction model have been described recently. In the current study, I present further improvements in terms of a generalized integrated form of the Michaelis-Menten equation for computation of substrate or product concentrations as functions of time for more real-world, enzyme-catalyzed reactions affected by the product. The explicit equations presented here can be considered as a simpler and useful alternative to the exact solution for the generalized integrated Michaelis-Menten equation when fitted to time course data using standard curve-fitting software. Copyright © 2011 Elsevier Inc. All rights reserved.
Fundamental solutions to time-fractional heat conduction equations in two joint half-lines
Povstenko, Yuriy
2013-10-01
Heat conduction in two joint half-lines is considered under the condition of perfect contact, i.e. when the temperatures at the contact point and the heat fluxes through the contact point are the same for both regions. The heat conduction in one half-line is described by the equation with the Caputo time-fractional derivative of order α, whereas heat conduction in another half-line is described by the equation with the time derivative of order β. The fundamental solutions to the first and second Cauchy problems as well as to the source problem are obtained using the Laplace transform with respect to time and the cos-Fourier transform with respect to the spatial coordinate. The fundamental solutions are expressed in terms of the Mittag-Leffler function and the Mainardi function.
On spurious resonant modes in the MOT solution of time domain EFIE
Shi, Yifei
2013-07-01
Theoretically, internal resonant modes should not be induced in the marching-on-in-time (MOT) solution of the time domain electric field integral equation since zero initial conditions are enforced at the beginning of time marching and the internal resonant modes do not satisfy these initial conditions. However, these spurious modes are always observed in the MOT solution. It has been conjectured in the past that numerical errors might establish the necessary initial conditions and allow the incident field to induce the internal resonant modes. Systematic numerical experiments carried out in this work prove this conjecture by demonstrating that the internal resonant modes\\' amplitudes are indeed dictated by the numerical errors and the spectrum of the incident field. © 2013 IEEE.
Continuous Time Random Walks for Non-Local Radial Solute Transport
Dentz, Marco; Borgne, Tanguy le
2016-01-01
This paper derives and analyzes continuous time random walk (CTRW) models in radial flow geometries for the quantification of non-local solute transport induced by heterogeneous flow distributions and by mobile-immobile mass transfer processes. To this end we derive a general CTRW framework in radial coordinates starting from the random walk equations for radial particle positions and times. The particle density, or solute concentration is governed by a non-local radial advection-dispersion equation (ADE). Unlike in CTRWs for uniform flow scenarios, particle transition times here depend on the radial particle position, which renders the CTRW non-stationary. As a consequence, the memory kernel characterizing the non-local ADE, is radially dependent. Based on this general formulation, we derive radial CTRW implementations that (i) emulate non-local radial transport due to heterogeneous advection, (ii) model multirate mass transfer (MRMT) between mobile and immobile continua, and (iii) quantify both heterogeneou...
Exact solutions of unsteady Korteweg-de Vries and time regularized long wave equations.
Islam, S M Rayhanul; Khan, Kamruzzaman; Akbar, M Ali
2015-01-01
In this paper, we implement the exp(-Φ(ξ))-expansion method to construct the exact traveling wave solutions for nonlinear evolution equations (NLEEs). Here we consider two model equations, namely the Korteweg-de Vries (KdV) equation and the time regularized long wave (TRLW) equation. These equations play significant role in nonlinear sciences. We obtained four types of explicit function solutions, namely hyperbolic, trigonometric, exponential and rational function solutions of the variables in the considered equations. It has shown that the applied method is quite efficient and is practically well suited for the aforementioned problems and so for the other NLEEs those arise in mathematical physics and engineering fields. PACS numbers: 02.30.Jr, 02.70.Wz, 05.45.Yv, 94.05.Fq.
Series Solution for the Time-Fractional Coupled mKdV Equation Using the Homotopy Analysis Method
Directory of Open Access Journals (Sweden)
J. F. Gómez-Aguilar
2016-01-01
Full Text Available We present new analytical approximated solutions for the space-time fractional nonlinear partial differential coupled mKdV equation. A homotopy analysis method is considered to obtain an infinite series solution. The effectiveness of this method is demonstrated by finding exact solutions of the fractional equation proposed, for the special case when the limit of the integral order of the time derivative is considered. The comparison shows a precise agreement between these solutions.
Directory of Open Access Journals (Sweden)
Maria de Hoyos Guajardo, Ph.D. Candidate, M.Sc., B.Eng.
2004-11-01
Full Text Available The theory that is presented below aims to conceptualise how a group of undergraduate students tackle non-routine mathematical problems during a problem-solving course. The aim of the course is to allow students to experience mathematics as a creative process and to reflect on their own experience. During the course, students are required to produce a written ‘rubric’ of their work, i.e., to document their thoughts as they occur as well as their emotionsduring the process. These ‘rubrics’ were used as the main source of data.Students’ problem-solving processes can be explained as a three-stage process that has been called ‘solutioning’. This process is presented in the six sections below. The first three refer to a common area of concern that can be called‘generating knowledge’. In this way, generating knowledge also includes issues related to ‘key ideas’ and ‘gaining understanding’. The third and the fourth sections refer to ‘generating’ and ‘validating a solution’, respectively. Finally, once solutions are generated and validated, students usually try to improve them further before presenting them as final results. Thus, the last section deals with‘improving a solution’. Although not all students go through all of the stages, it may be said that ‘solutioning’ considers students’ main concerns as they tackle non-routine mathematical problems.
Leray, Sarah; Engdahl, Nicholas B.; Massoudieh, Arash; Bresciani, Etienne; McCallum, James
2016-12-01
This review presents the physical mechanisms generating residence time distributions (RTDs) in hydrologic systems with a focus on steady-state analytical solutions. Steady-state approximations of the RTD in hydrologic systems have seen widespread use over the last half-century because they provide a convenient, simplified modeling framework for a wide range of problems. The concept of an RTD is useful anytime that characterization of the timescales of flow and transport in hydrologic systems is important, which includes topics like water quality, water resource management, contaminant transport, and ecosystem preservation. Analytical solutions are often adopted as a model of the RTD and a broad spectrum of models from many disciplines has been applied. Although these solutions are typically reduced in dimensionality and limited in complexity, their ease of use makes them preferred tools, specifically for the interpretation of tracer data. Our review begins with the mechanistic basis for the governing equations, highlighting the physics for generating a RTD, and a catalog of analytical solutions follows. This catalog explains the geometry, boundary conditions and physical aspects of the hydrologic systems, as well as the sampling conditions, that altogether give rise to specific RTDs. The similarities between models are noted, as are the appropriate conditions for their applicability. The presentation of simple solutions is followed by a presentation of more complicated analytical models for RTDs, including serial and parallel combinations, lagged systems, and non-Fickian models. The conditions for the appropriate use of analytical solutions are discussed, and we close with some thoughts on potential applications, alternative approaches, and future directions for modeling hydrologic residence time.
Analytical approximate solution for nonlinear space-time fractional Klein-Gordon equation
Institute of Scientific and Technical Information of China (English)
Khaled A.Gepreel; Mohamed S.Mohamed
2013-01-01
The fractional derivatives in the sense of Caputo and the homotopy analysis method are used to construct an approximate solution for the nonlinear space-time fractional derivatives Klein-Gordon equation.The numerical results show that the approaches are easy to implement and accurate when applied to the nonlinear space-time fractional derivatives KleinGordon equation.This method introduces a promising tool for solving many space-time fractional partial differential equations.This method is efficient and powerful in solving wide classes of nonlinear evolution fractional order equations.
Discrete-time dynamic graphical games:model-free reinforcement learning solution
Institute of Scientific and Technical Information of China (English)
Mohammed I ABOUHEAF; Frank L LEWIS; Magdi S MAHMOUD; Dariusz G MIKULSKI
2015-01-01
This paper introduces a model-free reinforcement learning technique that is used to solve a class of dynamic games known as dynamic graphical games. The graphical game results from multi-agent dynamical systems, where pinning control is used to make all the agents synchronize to the state of a command generator or a leader agent. Novel coupled Bellman equations and Hamiltonian functions are developed for the dynamic graphical games. The Hamiltonian mechanics are used to derive the necessary conditions for optimality. The solution for the dynamic graphical game is given in terms of the solution to a set of coupled Hamilton-Jacobi-Bellman equations developed herein. Nash equilibrium solution for the graphical game is given in terms of the solution to the underlying coupled Hamilton-Jacobi-Bellman equations. An online model-free policy iteration algorithm is developed to learn the Nash solution for the dynamic graphical game. This algorithm does not require any knowledge of the agents’ dynamics. A proof of convergence for this multi-agent learning algorithm is given under mild assumption about the inter-connectivity properties of the graph. A gradient descent technique with critic network structures is used to implement the policy iteration algorithm to solve the graphical game online in real-time.
Meghraoui, M.; Gomez, F.; Sbeinati, R.; Van der Woerd, J.; Mouty, M.; Hijazi, F.; Darkal, A.; Darawcheh, R.; Radwan, Y.; Al-Najjar, H.; Layous, I.; Al-Ghazzi, R.; Barazangi, M.
2001-12-01
We investigate the timing of Holocene earthquakes and related slip rate along the main segment of the Dead Sea fault south of the Ghab pull-apart basin in western Syria. The 60-70 km long Missyaf segment consists of a single fault branch of the north-south trending left-lateral fault at the plate boundary between Africa and Arabia. The late Quaternary tectonic activity along the fault is characterized by (1) deflected streams with consistent left-lateral displacements of different sizes (50 to 300 m), and (2) evidence of large shutter-ridge structures and small pull-apart basins. Microtopographic surveys and trenching across the fault at two sites document the size and timing of paleoseismic events and the related faulting behavior. Near El Harif village, the fault cut across a Roman aqueduct (younger than 22 AD) and induces 10.5 ±0.1 m of left-lateral displacement. Nearby trench-excavations and test pits exhibit the fault with the shear zone affecting a succession of young alluvial deposits of a terrace meander. Radiocarbon dating of the faulting events with vertical displacements reveal the occurrence of a large seismic event prior to 408-380 BC, a penultimate event between 22 - 979 AD and the most recent event between 979 - 1255 AD. The two most recent events being most likely responsible for the Roman aqueduct total displacement, it implies an average coseismic left-lateral movement of 5 m and a slip rate of about 5 mm/yr. The correlation with the historical seismicity catalogue suggests that the most recent faulting event may correspond to the well documented large earthquake of 1170 AD.
Meghraoui, M.; Gomez, F.; Sbeinati, R.; van der Woerd, J.; Mouty, M.; Darkal, A.; Darawcheh, R.; Radwan, Y.; Al-Ghazzi, R.; Barazangi, M.
We investigate the timing of Holocene earthquakes and related slip rate along the main segment of the Dead Sea fault south of the Ghab pull-apart basin in western Syria. The 60-70 km long Missyaf segment consists of a single fault branch of the north-south trending left-lateral fault at the plate boundary between Africa and Arabia. The late Quaternary tectonic activity along the fault is characterized by (1) deflected streams with consistent left-lateral displacements of different sizes (50 to 300 m), and (2) ev- idence of large shutter-ridge structures and small pull-apart basins. Microtopographic surveys and trenching across the fault at two sites document the size and timing of paleoseismic events and the related faulting behaviour. Near El Harif village, the fault cut across a Roman aqueduct (younger than 22 AD) and induces 13.6 s0.1 m of left-´ lateral displacement. Nearby trench-excavations and test pits exhibit the fault with the shear zone affecting a succession of young alluvial deposits of a terrace meander. First radiocarbon dating of the faulting events with vertical displacements reveal the occur- rence of a large seismic event prior to 348 BC - 810 BC, a penultimate event between 650 - 1152 AD and the most recent event between 979 - 1255 AD. The two most re- cent events being most likely responsible for the Roman aqueduct total displacement, it implies a coseismic left-lateral movement of 6.8 m per event at this location and a slip rate of about 6 - 7 mm/yr for the last 2000 years. The correlation with the histor- ical seismicity catalogue suggests that the most recent faulting event may correspond to the well documented large earthquake of 1170 AD for which we estimate Mw = 7.3 - 7.5.
Warped $AdS_6\\times S^2$ in Type IIB supergravity I: Local solutions
D'Hoker, Eric; Karch, Andreas; Uhlemann, Christoph F
2016-01-01
We investigate the existence of solutions with 16 residual supersymmetries to Type IIB supergravity on a space-time of the form $AdS_6 \\times S^2$ warped over a two-dimensional Riemann surface $\\Sigma$. The $SO(2,5) \\times SO(3)$ isometry extends to invariance under the exceptional Lie superalgebra $F(4)$. In the present paper, we construct the general Ansatz compatible with these symmetries, derive the corresponding reduced BPS equations, and obtain their complete local solution in terms of two locally holomorphic functions ${\\cal A}_\\pm$ on $\\Sigma$, subject to certain positivity and regularity conditions. Globally, $({\\cal A}_+, {\\cal A}_-)$ are allowed to be multiple-valued on $\\Sigma$ and be holomorphic sections of a holomorphic bundle over $\\Sigma$ with structure group contained in $SU(1,1) \\times { C}$. Globally regular solutions are expected to provide the near-horizon geometry of $(p,q)$ 5-brane and 7-brane webs which are holographic duals to five-dimensional conformal field theories. A preliminary a...
A hepatitis C virus infection model with time-varying drug effectiveness: solution and analysis.
Directory of Open Access Journals (Sweden)
Jessica M Conway
2014-08-01
Full Text Available Simple models of therapy for viral diseases such as hepatitis C virus (HCV or human immunodeficiency virus assume that, once therapy is started, the drug has a constant effectiveness. More realistic models have assumed either that the drug effectiveness depends on the drug concentration or that the effectiveness varies over time. Here a previously introduced varying-effectiveness (VE model is studied mathematically in the context of HCV infection. We show that while the model is linear, it has no closed-form solution due to the time-varying nature of the effectiveness. We then show that the model can be transformed into a Bessel equation and derive an analytic solution in terms of modified Bessel functions, which are defined as infinite series, with time-varying arguments. Fitting the solution to data from HCV infected patients under therapy has yielded values for the parameters in the model. We show that for biologically realistic parameters, the predicted viral decay on therapy is generally biphasic and resembles that predicted by constant-effectiveness (CE models. We introduce a general method for determining the time at which the transition between decay phases occurs based on calculating the point of maximum curvature of the viral decay curve. For the parameter regimes of interest, we also find approximate solutions for the VE model and establish the asymptotic behavior of the system. We show that the rate of second phase decay is determined by the death rate of infected cells multiplied by the maximum effectiveness of therapy, whereas the rate of first phase decline depends on multiple parameters including the rate of increase of drug effectiveness with time.
Hamiltonian formulation and exact solutions of the Bianchi type I space-time in conformal gravity
Demaret, J; Scheen, C
1999-01-01
We develop a Hamiltonian formulation of the Bianchi type I space-time in conformal gravity, i.e. the theory described by a Lagrangian that is defined by the contracted quadratic product of the Weyl tensor, in a four-dimensional space-time. We derive the explicit forms of the super-Hamiltonian and of the constraint expressing the conformal invariance of the theory and we write down the system of canonical equations. To seek out exact solutions of this system we add extra constraints on the canonical variables and we go through a global involution algorithm which eventually leads to the closure of the constraint algebra. The Painleve approach provides us with a proof of non-integrability, as a consequence of the presence of movable logarithms in the general solution of the problem. We extract all possible particular solutions that may be written in closed analytical form. This enables us to demonstrate that the global involution algorithm has brought forth the complete list of exact solutions that may be writte...
Directory of Open Access Journals (Sweden)
Česenek Jan
2016-01-01
Full Text Available In this article we deal with numerical simulation of the non-stationary compressible turbulent flow. Compressible turbulent flow is described by the Reynolds-Averaged Navier-Stokes (RANS equations. This RANS system is equipped with two-equation k-omega turbulence model. These two systems of equations are solved separately. Discretization of the RANS system is carried out by the space-time discontinuous Galerkin method which is based on piecewise polynomial discontinuous approximation of the sought solution in space and in time. Discretization of the two-equation k-omega turbulence model is carried out by the implicit finite volume method, which is based on piecewise constant approximation of the sought solution. We present some numerical experiments to demonstrate the applicability of the method using own-developed code.
Hybrid resonance and long-time asymptotic of the solution to Maxwell's equations
Després, Bruno
2015-01-01
We study the long-time asymptotic of the solutions to Maxwell's equation in the case of a hybrid resonance in the cold plasma model. We base our analysis in the transfer to the time domain of the recent results of B. Despr\\'es, L.M. Imbert-G\\'erard and R. Weder, J. Math. Pures Appl. {\\bf 101} ( 2014) 623-659, where the singular solutions to Maxwell's equations in the frequency domain where constructed by means of a limiting absorption principle and a formula for the heating of the plasma in the limit of vanishing collision frequency was obtained. Currently there is considerable interest in these problems because hybrid resonances are a possible scenario for the heating of plasmas in the future ITER Tokamak.
Hybrid resonance and long-time asymptotic of the solution to Maxwell's equations
Després, Bruno; Weder, Ricardo
2016-03-01
We study the long-time asymptotic of the solutions to Maxwell's equation in the case of an upper-hybrid resonance in the cold plasma model. We base our analysis in the transfer to the time domain of the recent results of B. Després, L.M. Imbert-Gérard and R. Weder (2014) [15], where the singular solutions to Maxwell's equations in the frequency domain were constructed by means of a limiting absorption principle and a formula for the heating of the plasma in the limit of vanishing collision frequency was obtained. Currently there is considerable interest in these problems, in particular, because upper-hybrid resonances are a possible scenario for the heating of plasmas, and since they can be a model for the diagnostics involving wave scattering in plasmas.
Approximate self-similar solutions to a nonlinear diffusion equation with time-fractional derivative
Płociniczak, Łukasz; Okrasińska, Hanna
2013-10-01
In this paper, we consider a fractional nonlinear problem for anomalous diffusion. The diffusion coefficient we use is of power type, and hence the investigated problem generalizes the porous-medium equation. A generalization is made by introducing a fractional time derivative. We look for self-similar solutions for which the fractional setting introduces other than classical space-time scaling. The resulting similarity equations are of nonlinear integro-differential type. We approximate these equations by an expansion of the integral operator and by looking for solutions in a power function form. Our method can be easily adapted to solve various problems in self-similar diffusion. The approximations obtained give very good results in numerical analysis. Their simplicity allows for easy use in applications, as our fitting with experimental data shows. Moreover, our derivation justifies theoretically some previously used empirical models for anomalous diffusion.
LARGE TIME BEHAVIOR OF SOLUTIONS TO NONLINEAR VISCOELASTIC MODEL WITH FADING MEMORY
Institute of Scientific and Technical Information of China (English)
Yanni Zeng
2012-01-01
We study the Cauchy problem of a one-dimensional nonlinear viscoelastic model with fading memory. By introducing appropriate new variables we convert the integro-partial differential equations into a hyperbolic system of balance laws.When it is a perturbation of a constant state,the solution is shown time asymptotically approaching to predetermined diffusion waves.Pointwise estimates on the convergence details are obtained.
Said-Houari, Belkacem
2012-03-01
In this paper, we consider a viscoelastic wave equation with an absorbing term and space-time dependent damping term. Based on the weighted energy method, and by assuming that the kernel decaying exponentially, we obtain the L2 decay rates of the solutions. More precisely, we show that the decay rates are the same as those obtained in Lin et al. (2010) [15] for the semilinear wave equation with absorption term. © 2011 Elsevier Inc.
A comparison of numerical methods for the solution of continuous-time DSGE models
DEFF Research Database (Denmark)
Parra-Alvarez, Juan Carlos
This paper evaluates the accuracy of a set of techniques that approximate the solution of continuous-time DSGE models. Using the neoclassical growth model I compare linear-quadratic, perturbation and projection methods. All techniques are applied to the HJB equation and the optimality conditions...... parameters of the model and suggest the use of projection methods when a high degree of accuracy is required....
Institute of Scientific and Technical Information of China (English)
Fa-yong Zhang; Shu-juan Lu
2001-01-01
A weakly demped Schrodinger equation possessing a global attractor are considered.The dynamical properties of a class of finite difference scheme are analysed. The exsitence of global attractor is proved for the discrete system. The stability of the difference scheme and the error estimate of the difference solution are obtained in the autonomous system case. Finally, long-time stability and convergence of the class of finite difference scheme also are analysed in the nonautonomous system case.
Estimates for solutions to a class of nonlinear time-delay systems of neutral type
Directory of Open Access Journals (Sweden)
Gennadii V. Demidenko
2015-02-01
Full Text Available We consider nonlinear time-delay systems of neutral type with constant coefficients in the linear terms, $$ \\frac{d}{dt}\\big(y(t + D y(t-\\tau\\big = A y(t + B y(t-\\tau + F(t, y(t, y(t-\\tau. $$ We obtain estimates characterizing the exponential decay of solutions at infinity, and dependending on the norms of the powers of D.
Directory of Open Access Journals (Sweden)
Veysel Hatipoglu
2015-09-01
Full Text Available In this study, we present a practical matrix method to find an approximate solution of higher order linear difference equation with constant coefficients under the initial-boundary conditions in terms of Taylor polynomials. To obtain this goal, we first present time scale extension of previous polynomial approach, then restrict the formula to the Integers with h step. This method converts the difference equation to a matrix equation, which may be considered as a system of linear algebraic equations.
Lie algebra solution of population models based on time-inhomogeneous Markov chains
House, Thomas
2011-01-01
Many natural populations are well modelled through time-inhomogeneous stochastic processes. Such processes have been analysed in the physical sciences using a method based on Lie algebras, but this methodology is not widely used for models with ecological, medical and social applications. This paper presents the Lie algebraic method, and applies it to three biologically well motivated examples. The result of this is a solution form that is often highly computationally advantageous.
Existence of Positive Solutions for Higher Order Boundary Value Problem on Time Scales
Institute of Scientific and Technical Information of China (English)
XIE DA-PENG; LIU YANG; SUN MING-ZHE; Li Yong
2013-01-01
In this paper,we investigate the existence of positive solutions of a class higher order boundary value problems on time scales.The class of boundary value problems educes a four-point (or three-point or two-point) boundary value problems,for which some similar results are established.Our approach relies on the Krasnosel'skii fixed point theorem.The result of this paper is new and extends previously known results.
Relativistic star solutions in higher-dimensional pseudospheroidal space-time
Indian Academy of Sciences (India)
P K Chattopadhyay; B C Paul
2010-04-01
We obtain relativistic solutions of a class of compact stars in hydrostatic equilibrium in higher dimensions by assuming a pseudospheroidal geometry for the space-time. The space-time geometry is assumed to be ( - 1) pseudospheroid immersed in a -dimensional Euclidean space. The spheroidicity parameter () plays an important role in determining the equation of state of the matter content and the maximum radius of such stars. It is found that the core density of compact objects is approximately proportional to the square of the space-time dimensions (), i.e., core of the star is denser in higher dimensions than that in conventional four dimensions. The central density of a compact star is also found to depend on the parameter . One obtains a physically interesting solution satisfying the acoustic condition when lies in the range > ( + 1)/( − 3) for the space-time dimensions ranging from = 4 to 8 and ( + 1)/( − 3) < < (2 - 4 + 3)/(2 - 8 - 1) for space-time dimensions ≥ 9. The non-negativity of the energy density () constrains the parameter with a lower limit (> 1). We note that in the case of a superdense compact object the number of space-time dimensions cannot be taken infinitely large, which is a different result from the braneworld model.
Effects of deposition time in chemically deposited ZnS films in acidic solution
Energy Technology Data Exchange (ETDEWEB)
Haddad, H.; Chelouche, A., E-mail: azeddinechelouche@gmail.com; Talantikite, D.; Merzouk, H.; Boudjouan, F.; Djouadi, D.
2015-08-31
We report an experimental study on the synthesis and characterization of zinc sulfide (ZnS) single layer thin films deposited on glass substrates by chemical bath deposition technique in acidic solution. The effect of deposition time on the microstructure, surface morphology, optical absorption, transmittance, and photoluminescence (PL) was investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM), UV-Vis–NIR spectrophotometry and photoluminescence (PL) spectroscopy. The results showed that the samples exhibit wurtzite structure and their crystal quality is improved by increasing deposition time. The latter, was found to affect the morphology of the thin films as showed by SEM micrographs. The optical measurements revealed a high transparency in the visible range and a dependence of absorption edge and band gap on deposition time. The room temperature PL spectra indicated that all ZnS grown thin films emit a UV and blue light, while the band intensities are found to be dependent on deposition times. - Highlights: • Single layer ZnS thin films were deposited by CBD in acidic solution at 95 °C. • The effect of deposition time was investigated. • Coexistence of ZnS and ZnO hexagonal structures for time deposition below 2 h • Thicker ZnS films were achieved after monolayer deposition for 5 h. • The highest UV-blue emission observed in thin film deposited at 5 h.
Hybrid resonance and long-time asymptotic of the solution to Maxwell's equations
Energy Technology Data Exchange (ETDEWEB)
Després, Bruno, E-mail: despres@ann.jussieu.fr [Laboratory Jacques Louis Lions, University Pierre et Marie Curie, Paris VI, Boîte courrier 187, 75252 Paris Cedex 05 (France); Weder, Ricardo, E-mail: weder@unam.mx [Departamento de Física Matemática, Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad Nacional Autónoma de México, Apartado Postal 20-126, DF 01000 (Mexico)
2016-03-22
We study the long-time asymptotic of the solutions to Maxwell's equation in the case of an upper-hybrid resonance in the cold plasma model. We base our analysis in the transfer to the time domain of the recent results of B. Després, L.M. Imbert-Gérard and R. Weder (2014) [15], where the singular solutions to Maxwell's equations in the frequency domain were constructed by means of a limiting absorption principle and a formula for the heating of the plasma in the limit of vanishing collision frequency was obtained. Currently there is considerable interest in these problems, in particular, because upper-hybrid resonances are a possible scenario for the heating of plasmas, and since they can be a model for the diagnostics involving wave scattering in plasmas. - Highlights: • The upper-hybrid resonance in the cold plasma model is considered. • The long-time asymptotic of the solutions to Maxwell's equations is studied. • A method based in a singular limiting absorption principle is proposed.
An explicit time domain solution for ground stratum response to harmonic moving loan
Institute of Scientific and Technical Information of China (English)
Xuecheng Bian; Yunmin Chen
2006-01-01
Based on the thin 1ayer method originally proposed in frequency domain, an explicit time domain semi-analytical solution has been developed for simulating three-dimensional layered ground responses to harmonic moving loads. The Fourier-Laplace transforms were applied to derive the transformed solution that satisfied the boundary conditions of horizontal infinities. The eigenvalue decomposition was performed with respect to Laplace parameter to express the ground motion corresponding to the eigenmodes. The formulation for each eigenmode incorporating the moving load expression was transformed back into time domain analytically, and the global system responses were given by means of the general mode superposition method. The proposed explicit time domain solution is suitable for studying various types of moving load acting on or inside the ground. In this paper a moving harmonic load with rectangular distribution was adopted to demonstrate the ground response simulation. Two illustrative examples for moving load with speeds below or above the ground Rayleigh wave velocity were presented to test the computational accuracy and efficiency of the proposed approach. A parametric study was also performed to investigate the influences of soil properties on the ground responses.
Directory of Open Access Journals (Sweden)
Luciana Trigueiro de Andrade
2015-03-01
Full Text Available Sodium metabisulfite is the main additive used in the prevention of melanosis in shrimp; however, it has currently been employed with great variation in concentration by producers. Thus, the aim of the present study was to determine the correlation between the concentration of the sodium metabisulfite solution and immersion time of the whole shrimp to obtain the concentration of sulfur dioxide (SO2 in the edible muscle of farmed shrimp (Litopenaeus vannamei in accordance with the limit established by law. For this, solutions of sodium metabisulfite at different concentrations (1%, 2 %, 3 %, 4% and 5% were prepared and samples of L. vannamei shrimp (100g were immersed during 10, 20 or 30 minutes at temperature of 7°C. For all treatment assayed the concentration of SO2 was determined in the edible muscle of farmed shrimp (L. vannamei. The results show that for the conditions used in this study, the correlations were linear, with significant increase (P<0.05 in the SO2 concentration in the edible muscle of shrimps both increasing sodium metabisulfite concentration as increasing immersion times, suggesting the immersion of shrimps in a 3% solution for a time of 13 minutes in order to obtain SO2 concentration of 100ppm in its edible muscle in accordance with Brazilian legislation
Near real-time GRACE gravity field solutions for hydrological monitoring applications
Kvas, Andreas; Gouweleeuw, Ben; Mayer-Gürr, Torsten; Güntner, Andreas
2016-04-01
Within the EGSIEM (European Gravity Service for Improved Emergency Management) project, a demonstrator for a near real-time (NRT) gravity field service which provides daily GRACE gravity field solutions will be established. Compared to the official GRACE gravity products, these NRT solutions will increase the temporal resolution from one month to one day and reduce the latency from currently two months to five days. This fast availability allows the monitoring of total water storage variations and of hydrological extreme events as they occur, in contrast to a 'confirmation after occurrence' as is the situation today. The service will be jointly run by GFZ (German Research Centre for Geosciences) and Graz University of Technology, with each analysis center providing an independent solution. A Kalman filter framework, in which GRACE data is combined with prior information, serves as basis for the gravity field recovery in order to increase the redundancy of the gravity field estimates. The on-line nature of the NRT service necessitates a tailored smoothing algorithm as opposed to post-processing applications, where forward-backward smoothing can be applied. This contribution gives an overview on the near real-time processing chain and highlights differences between the computed NRT solutions and the standard GRACE products. We discuss the special characteristics of the Kalman filtered gravity field models as well as derived products and give an estimate of the expected error levels. Additionally, we show the added value of the NRT solutions through comparison of the first results of the pre-operational phase with in-situ data and monthly GRACE gravity field models.
DEFF Research Database (Denmark)
Sørensen, Jette Led; Thranov, I; Hoff, G
1994-01-01
in order to detect an early- and late-onset pelvic inflammatory disease (PID). For statistical analysis survival analysis by Kaplan-Meir estimates and Mantel-Cox test were carried out. Untreated women with C. trachomatis infection at the time of abortion had a cumulative risk of 72% of developing early and...
Directory of Open Access Journals (Sweden)
Majid Eshaghi
Full Text Available BACKGROUND: During S. pombe S-phase, initiation of DNA replication occurs at multiple sites (origins that are enriched with AT-rich sequences, at various times. Current studies of genome-wide DNA replication profiles have focused on the DNA replication timing and origin location. However, the replication and/or firing efficiency of the individual origins on the genomic scale remain unclear. METHODOLOGY/PRINCIPAL FINDINGS: Using the genome-wide ORF-specific DNA microarray analysis, we show that in S. pombe, individual origins fire with varying efficiencies and at different times during S-phase. The increase in DNA copy number plotted as a function of time is approximated to the near-sigmoidal model, when considering the replication start and end timings at individual loci in cells released from HU-arrest. Replication efficiencies differ from origin to origin, depending on the origin's firing efficiency. We have found that DNA replication is inefficient early in S-phase, due to inefficient firing at origins. Efficient replication occurs later, attributed to efficient but late-firing origins. Furthermore, profiles of replication timing in cds1Delta cells are abnormal, due to the failure in resuming replication at the collapsed forks. The majority of the inefficient origins, but not the efficient ones, are found to fire in cds1Delta cells after HU removal, owing to the firing at the remaining unused (inefficient origins during HU treatment. CONCLUSIONS/SIGNIFICANCE: Taken together, our results indicate that efficient DNA replication/firing occurs late in S-phase progression in cells after HU removal, due to efficient late-firing origins. Additionally, checkpoint kinase Cds1p is required for maintaining the efficient replication/firing late in S-phase. We further propose that efficient late-firing origins are essential for ensuring completion of DNA duplication by the end of S-phase.
Xie, Hui; Song, Kang; He, Yu
2014-07-01
A novel solution for electro-hydraulic variable valve timing (VVT) system of gasoline engines is proposed, based on the concept of active disturbance rejection control (ADRC). Disturbances, such as oil pressure and engine speed variations, are all estimated and mitigated in real-time. A feed-forward controller was added to enhance the performance of the system based on a simple and static first principle model, forming a hybrid disturbance rejection control (HDRC) strategy. HDRC was validated by experimentation and compared with an existing manually tuned proportional-integral (PI) controller. The results show that HDRC provided a faster response and better tolerance of engine speed and oil pressure variations.
Time-dependent solution for the manufacturing line with unreliable machine and batched arrivals
Kempa, W. M.; Paprocka, I.; Grabowik, C.; Kalinowski, K.
2015-11-01
Time-dependent queue-size distribution in a finite-buffer manufacturing line with unreliable machine is investigated. Successive jobs arrive in batches (groups) with sizes being generally distributed random variables, and are being processed individually with exponential service times. Applying the approach based on the memory less property of exponential distribution and the total probability law, a system of integral equations for the transient queue- size distribution conditioned by the initial level of buffer saturation is derived. The solution of the corresponding system written for Laplace transforms is found via linear-algebraic approach.
Csörgö, T; Csanad, M
2007-01-01
A new class of accelerating, exact, explicit and simple solutions of relativistic hydrodynamics is presented. Since these new solutions yield a finite rapidity distribution, they lead to an advanced estimate of the initial energy density and life-time of high energy heavy ion reactions. Accelerating solutions are also given for spherical expansions in arbitrary number of spatial dimensions.
Martín Furones, Angel; Anquela Julián, Ana Belén; Dimas-Pages, Alejandro; Cos-Gayón, Fernando
2017-08-01
Precise point positioning (PPP) is a well established Global Navigation Satellite System (GNSS) technique that only requires information from the receiver (or rover) to obtain high-precision position coordinates. This is a very interesting and promising technique because eliminates the need for a reference station near the rover receiver or a network of reference stations, thus reducing the cost of a GNSS survey. From a computational perspective, there are two ways to solve the system of observation equations produced by static PPP either in a single step (so-called batch adjustment) or with a sequential adjustment/filter. The results of each should be the same if they are both well implemented. However, if a sequential solution (that is, not only the final coordinates, but also those observed in previous GNSS epochs), is needed, as for convergence studies, finding a batch solution becomes a very time consuming task owing to the need for matrix inversion that accumulates with each consecutive epoch. This is not a problem for the filter solution, which uses information computed in the previous epoch for the solution of the current epoch. Thus filter implementations need extra considerations of user dynamics and parameter state variations between observation epochs with appropriate stochastic update parameter variances from epoch to epoch. These filtering considerations are not needed in batch adjustment, which makes it attractive. The main objective of this research is to significantly reduce the computation time required to obtain sequential results using batch adjustment. The new method we implemented in the adjustment process led to a mean reduction in computational time by 45%.
Hrabe, J.; Lewis, D. P.
2004-03-01
A fairly general theoretical model for pulsed arterial spin labeling perfusion methods has been available for some time but analytical solutions were derived for only a small number of arterial blood input functions. These mostly assumed a sudden and simultaneous arrival of the tagged blood into the imaged region. More general cases had to be handled numerically. We present analytical solutions for two more realistic arterial input functions. They both allow the arrival times of the molecules of tagged arterial blood to be statistically distributed. We consider cases of (1) a uniform distribution on a finite time interval and (2) a normal distribution characterized by its mean and standard deviation. These models are physiologically meaningful because the statistical nature of the arrival times reflects the distribution of velocities and path lengths that the blood water molecules undertake from the tagging region to the imaged region. The model parameters can be estimated from the measured dependency of the perfusion signal on the tag inversion time.
Sanchez, J. Aquiles; Pierce, Kenneth E.; Rice, John E.; Wangh, Lawrence J.
2004-01-01
Conventional asymmetric PCR is inefficient and difficult to optimize because limiting the concentration of one primer lowers its melting temperature below the reaction annealing temperature. Linear-After-The-Exponential (LATE)–PCR describes a new paradigm for primer design that renders assays as efficient as symmetric PCR assays, regardless of primer ratio. LATE-PCR generates single-stranded products with predictable kinetics for many cycles beyond the exponential phase. LATE-PCR also introduces new probe design criteria that uncouple hybridization probe detection from primer annealing and extension, increase probe reliability, improve allele discrimination, and increase signal strength by 80–250% relative to symmetric PCR. These improvements in PCR are particularly useful for real-time quantitative analysis of target numbers in small samples. LATE-PCR is adaptable to high throughput applications in fields such as clinical diagnostics, biodefense, forensics, and DNA sequencing. We showcase LATE-PCR via amplification of the cystic fibrosis CFΔ508 allele and the Tay-Sachs disease TSD 1278 allele from single heterozygous cells. PMID:14769930
Protein structural dynamics revealed by time-resolved X-ray solution scattering.
Kim, Jong Goo; Kim, Tae Wu; Kim, Jeongho; Ihee, Hyotcherl
2015-08-18
One of the most important questions in biological science is how a protein functions. When a protein performs its function, it undergoes regulated structural transitions. In this regard, to better understand the underlying principle of a protein function, it is desirable to monitor the dynamic evolution of the protein structure in real time. To probe fast and subtle motions of a protein in physiological conditions demands an experimental tool that is not only equipped with superb spatiotemporal resolution but also applicable to samples in solution phase. Time-resolved X-ray solution scattering (TRXSS), discussed in this Account, fits all of those requirements needed for probing the movements of proteins in aqueous solution. The technique utilizes a pump-probe scheme employing an optical pump pulse to initiate photoreactions of proteins and an X-ray probe pulse to monitor ensuing structural changes. The technical advances in ultrafast lasers and X-ray sources allow us to achieve superb temporal resolution down to femtoseconds. Because X-rays scatter off all atomic pairs in a protein, an X-ray scattering pattern provides information on the global structure of the protein with subangstrom spatial resolution. Importantly, TRXSS is readily applicable to aqueous solution samples of proteins with the aid of theoretical models and therefore is well suited for investigating structural dynamics of protein transitions in physiological conditions. In this Account, we demonstrate that TRXSS can be used to probe real-time structural dynamics of proteins in solution ranging from subtle helix movement to global conformational change. Specifically, we discuss the photoreactions of photoactive yellow protein (PYP) and homodimeric hemoglobin (HbI). For PYP, we revealed the kinetics of structural transitions among four transient intermediates comprising a photocycle and, by applying structural analysis based on ab initio shape reconstruction, showed that the signaling of PYP involves
RDTM solution of Caputo time fractional-order hyperbolic telegraph equation
Directory of Open Access Journals (Sweden)
Vineet K. Srivastava
2013-03-01
Full Text Available In this study, a mathematical model has been developed for the second order hyperbolic one-dimensional time fractional Telegraph equation (TFTE. The fractional derivative has been described in the Caputo sense. The governing equations have been solved by a recent reliable semi-analytic method known as the reduced differential transformation method (RDTM. The method is a powerful mathematical technique for solving wide range of problems. Using RDTM method, it is possible to find exact solution as well as closed approximate solution of any ordinary or partial differential equation. Three numerical examples of TFTE have been provided in order to check the effectiveness, accuracy and convergence of the method. The computed results are also depicted graphically.
Explicit reformulations of time-dependent solution for a Michaelis-Menten enzyme reaction model.
Golicnik, Marko
2010-11-01
The exact closed-form solution to the Michaelis-Menten equation is expressed in terms of the Lambert W(x) function. However, the utility of this solution is limited because the W(x) function is not widely available in curve-fitting software. Based on various approximations to the W(x) function, different explicit equations expressed in terms of the elementary functions are proposed here as useful shortcuts to fit time depletion of substrate concentration directly to progress curves using commonly available nonlinear regression computer programs. The results are compared with those obtained by fitting other algebraic equations that have been proposed previously in the literature. 2010 Elsevier Inc. All rights reserved.
Time resolved fluorescence anisotropy of basic dyes bound to poly(methacrylic acid in solution
Directory of Open Access Journals (Sweden)
Oliveira Hueder Paulo M. de
2003-01-01
Full Text Available Solutions of atactic poly(methacrylic acid, PMAA, with molecular weights in the range of (1.6 to 3.4 x 10(5 g mol-1, and labeled with the fluorescent dyes 9-aminoacridine or Nile blue were studied by photophysical measurements as a function of solvent viscosity and polarity. The conformational behavior of the PMAA chain segments around the fluorescent probe was reported by the change in the rotational diffusion of the dyes. Ethylene glycol swells the polymer chain compared with the more contracted conformation of PMAA in 50% water/ethylene glycol. The change in the rotational relaxation time of the dye bound to PMAA with the decrease of water content in the solvent mixture indicates a progressive expansion of polymer chain to a more open coil form in solution.
On the Numerical Solutions for the Time-Fractional Telegraph Equation
Directory of Open Access Journals (Sweden)
Kobra Karimi
2013-02-01
Full Text Available Fractional differential equations have recently been applied in various area of engineering, science, finance, applied mathematics, bio-engineering and others.In this paper, an efficient numerical method for solving telegraph equation with fractional time derivative , is proposed. The fractional derivative is described in the Caputo sense. This technique is derived by expanding the required approximate solution as the elements of shifted Legendre polynomials. Using the operational matrix of the fractional derivative the problem can be reduced to a set of algebraic equations. From the computational point of view, the solution obtained by this method is in excellent agreement with those obtained by previous work in the literature and also it is efficient to use
DEFF Research Database (Denmark)
Kalinska-Nartisa, Edyta; Nartiss, Maris; Thiel, Christine;
2015-01-01
The Late-glacial and Holocene aeolian inland dune complex at Iisaku (NE Estonia) has been investigated using an accurate and detailed compilation of the sedimentary properties and chronological framework. The quartz grains forming the dunes are very variable, reflecting aeolian, weathering, and p...
Energy Technology Data Exchange (ETDEWEB)
Sand, David J.; Graham, Melissa L. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Bildfell, Chris; Pritchet, Chris [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, STN CSC, Victoria BC V8W 3P6 (Canada); Zaritsky, Dennis; Just, Dennis W.; Herbert-Fort, Stephane [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Hoekstra, Henk [Leiden Observatory, Leiden University, Niels Bohrweg 2, NL-2333 CA Leiden (Netherlands); Sivanandam, Suresh [Dunlap Institute for Astronomy and Astrophysics, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Foley, Ryan J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Mahdavi, Andisheh, E-mail: dsand@lcogt.net [Department of Physics and Astronomy, San Francisco State University, San Francisco, CA 94132 (United States)
2012-02-20
We describe the Multi-Epoch Nearby Cluster Survey, designed to measure the cluster Type Ia supernova (SN Ia) rate in a sample of 57 X-ray selected galaxy clusters, with redshifts of 0.05 < z < 0.15. Utilizing our real-time analysis pipeline, we spectroscopically confirmed twenty-three cluster SNe Ia, four of which were intracluster events. Using our deep Canada-France-Hawaii Telescope/MegaCam imaging, we measured total stellar luminosities in each of our galaxy clusters, and we performed detailed supernova (SN) detection efficiency simulations. Bringing these ingredients together, we measure an overall cluster SN Ia rate within R{sub 200} (1 Mpc) of 0.042{sup +0.012}{sub -0.010}{sup +0.010}{sub -0.008} SNuM (0.049{sup +0.016}{sub -0.014}{sup +0.005}{sub -0.004} SNuM) and an SN Ia rate within red-sequence galaxies of 0.041{sup +0.015}{sub -0.015}{sup +0.005}{sub -0.010} SNuM (0.041{sup +0.019}{sub -0.015}{sup +0.005}{sub -0.004} SNuM). The red-sequence SN Ia rate is consistent with published rates in early-type/elliptical galaxies in the 'field'. Using our red-sequence SN Ia rate, and other cluster SN measurements in early-type galaxies up to z {approx} 1, we derive the late-time (>2 Gyr) delay time distribution (DTD) of SN Ia assuming a cluster early-type galaxy star formation epoch of z{sub f} = 3. Assuming a power-law form for the DTD, {Psi}(t){proportional_to}t{sup s} , we find s = -1.62 {+-} 0.54. This result is consistent with predictions for the double degenerate SN Ia progenitor scenario (s {approx} -1) and is also in line with recent calculations for the double detonation explosion mechanism (s {approx} -2). The most recent calculations of the single degenerate scenario DTD predicts an order-of-magnitude drop-off in SN Ia rate {approx}6-7 Gyr after stellar formation, and the observed cluster rates cannot rule this out.
The reliable solution and computation time of variable parameters Logistic model
Pengfei, Wang
2016-01-01
The reliable computation time (RCT, marked as Tc) when applying a double precision computation of a variable parameters logistic map (VPLM) is studied. First, using the method proposed, the reliable solutions for the logistic map are obtained. Second, for a time-dependent non-stationary parameters VPLM, 10000 samples of reliable experiments are constructed, and the mean Tc is then computed. The results indicate that for each different initial value, the Tcs of the VPLM are generally different. However, the mean Tc trends to a constant value once the sample number is large enough. The maximum, minimum and probable distribution function of Tc is also obtained, which can help us to identify the robustness of applying a nonlinear time series theory to forecasting while using the VPLM output. In addition, the Tc of the fixed parameter experiments of the logistic map was obtained, and the results suggested that this Tc matches the theoretical formula predicted value.
TIME-ASYMPTOTIC BEHAVIOR OF SOLUTIONS FOR GENERAL NAVIER-STOKES EQUATIONS IN EVEN SPACE-DIMENSION
Institute of Scientific and Technical Information of China (English)
Xu Hongmei
2001-01-01
We study the time-asymptotic behavior of solutions to general NavierStokes equations in even and higher than two space-dimensions. Through the pointwise estimates of the Green function of the linearized system, we obtain explicit expressions of the time-asymptotic behavior of the solutions. The result coincides with weak Huygan's principle.
Fan, Gong-duan; Chen, Li-ru; Lin, Ru-jing; Lin, Qian; Su, Zhao-yue; Lin, Xiu-yong
2016-02-15
Titanate nanomaterials (TNs) were synthesized via a simple hydrothermal method using TiO2 (ST-01) and NaOH as the raw materials, and presented different morphologies by adjusting the reaction time. The physico-chemical properties of the as-prepared TNs, such as morphology, structure, surface area, and chemical composition were characterized by XRD, SEM and BET. The adsorption capability and rules of Pb(II) in aqueous solutions were tested in the static system. The results showed that the TNs prepared with 12-72 h reaction time were pure monoclinic phase titanate and their specific surface areas were in the range from 243.05 m2 x g(-1) to 286.20 m2 x g(-1). TNs with reaction time between 12-36 h mainly showed sheet structure, and those with reaction time higher than 48 h showed linear structure. The adsorption capacity of Pb(II) by TNs-12, TNs-24, TNs-36, TNs-48, TNs-60 and TNs-72 was 479.40, 504.12, 482.00, 388.10, 364.60 and 399.00 mg x g(-1), respectively. The sheet TNs had a better adsorption capacity than the linear TNs. TNs-24 had the highest adsorbing capacity. The adsorption kinetics of Pb(II) by TNs-24 followed the pseudo-second-order model, and the equilibrium data was best fitted with the Langmuir isotherm model. The equilibrium adsorption time of TNs-24 was 120 min, and the adsorption was an exothermic process, with a high adsorption capacity at low temperature or room temperature; the optimal adsorption pH was 5.0. When pH was 1.0, the desorption rate of TNs-24 could reach 99.00%, and the removal efficiency of Pb(II) by regenerated TNs was still more than 97% after six times of usage. Therefore, TNs could efficiently remove Pb(II) in aqueous solutions, and the optimal reaction time should be controlled to 12-24 h. When Cd(II) or Ni(II) existed in the solution, the equilibrium adsorption capacity and removal rate of TNs-24 were decreased. The adsorption mechanism was mainly ion-exchanged between Pb(II) and H+/Na+ in TNs.
a Solution to Low Rfm Fitting Precision of Planetary Orbiter Images Caused by Exposure Time Changing
Liu, B.; Xu, B.; Di, K.; Jia, M.
2016-06-01
In this paper, we propose a new solution to the low RFM fitting precision caused by exposure time changing using sensor correction. First, we establish a new rigorous geometric model, with the same ephemerides, attitudes and sensor design parameters of Chang'E-2 and HRSC images, using an equal exposure time of each scan line. The original rigorous geometric model is also established. With a given height, we can establish the correspondence between the two rigorous models. Then we generate a sensor corrected image by resampling the original image using an average elevation or a digital elevation model. We found that the sensor corrected images can be used for topographic mapping which maintains almost the same precision of the original images under certain conditions. And RFM can fit rigorous geometric model of the sensor corrected image very well. Preliminary experimental results show that the RMS residual error of the RFM fitting can reach to 1/100 pixel level too. Using the proposed solution, sensors with changing exposure time can be precisely modelled by the generic RFM.
Biofilm growth in gravel bed streams controls solute residence time distributions
Aubeneau, A. F.; Hanrahan, Brittany; Bolster, Diogo; Tank, Jennifer
2016-07-01
Streambed substrates harbor a rich biome responsible for biogeochemical processing in riverine waters. Beyond their biological role, the presence of benthic and hyporheic biofilms can play an important role in influencing large-scale transport of solutes, even for conservative tracers. As biofilms grow and accumulate biomass, they actively interact with and influence surface and subsurface flow patterns. To explore this effect, we conducted experiments at the Notre Dame Linked Ecosystems Experimental Facility in four outdoor streams, each with different gravel beds. Over the course of 20 weeks we conducted transport experiments in each of these streams and observed different patterns in breakthrough curves as biofilms grew on the substrate. Biofilms played a major role in shaping the observed conservative transport patterns. Overall, while the presence of biofilms led to a decreased exchange rate between the fast (mobile) and slow (immobile) parts of the flow domain, water that was exchanged tended to be stored in the slow regions for longer times once biofilms had established. More specifically, we observed enhanced longitudinal dispersion in breakthrough curves as well as broader residence time distributions when biofilms were present. Biofilm colonization over time homogenized transport patterns across the four streams that were originally very distinct. These results indicate that stream biofilms exert a strong control on conservative solute transport in streams, a role that to date has not received enough attention.
Variable time-stepping in the pathwise numerical solution of the chemical Langevin equation.
Ilie, Silvana
2012-12-21
Stochastic modeling is essential for an accurate description of the biochemical network dynamics at the level of a single cell. Biochemically reacting systems often evolve on multiple time-scales, thus their stochastic mathematical models manifest stiffness. Stochastic models which, in addition, are stiff and computationally very challenging, therefore the need for developing effective and accurate numerical methods for approximating their solution. An important stochastic model of well-stirred biochemical systems is the chemical Langevin Equation. The chemical Langevin equation is a system of stochastic differential equation with multidimensional non-commutative noise. This model is valid in the regime of large molecular populations, far from the thermodynamic limit. In this paper, we propose a variable time-stepping strategy for the numerical solution of a general chemical Langevin equation, which applies for any level of randomness in the system. Our variable stepsize method allows arbitrary values of the time-step. Numerical results on several models arising in applications show significant improvement in accuracy and efficiency of the proposed adaptive scheme over the existing methods, the strategies based on halving/doubling of the stepsize and the fixed step-size ones.
Analytic solutions for colloid transport with time- and depth-dependent retention in porous media
Leij, Feike J.; Bradford, Scott A.; Sciortino, Antonella
2016-12-01
Elucidating and quantifying the transport of industrial nanoparticles (e.g. silver, carbon nanotubes, and graphene oxide) and other colloid-size particles such as viruses and bacteria is important to safeguard and manage the quality of the subsurface environment. Analytic solutions were derived for aqueous and solid phase colloid concentrations in a porous medium where colloids were subject to advective transport and reversible time and/or depth-dependent retention. Time-dependent blocking and ripening retention were described using a Langmuir-type equation with a rate coefficient that respectively decreased and increased linearly with the retained concentration. Depth-dependent retention was described using a rate coefficient that is a power-law function of distance. The stream tube modeling concept was employed to extend these analytic solutions to transport scenarios with two different partitioning processes (i.e., two types of retention sites). The sensitivity of concentrations was illustrated for the various time- and/or depth-dependent retention model parameters. The developed analytical models were subsequently used to describe breakthrough curves and, in some cases, retention profiles from several published column studies that employed nanoparticle or pathogenic microorganisms. Simulations results provided valuable insights on causes for many observed complexities associated with colloid transport and retention, including: increasing or decreasing effluent concentrations with continued colloid application, delayed breakthrough, low concentration tailing, and retention profiles that are hyper-exponential, exponential, linear, or non-monotonic with distance.
Cho, Kyu-Hyang; Do, Jun-Young; Park, Jong-Won; Yoon, Kyung-Woo
2010-02-01
The purpose of this study was to analyse the changes of body composition and the effects of icodextrin dialysis solution over time on peritoneal dialysis (PD) in continuous ambulatory peritoneal dialysis (CAPD) patients. Among 183 incident patients, 75 patients finished a complete 36-month protocol. Clinical indices including daily glucose absorption and body composition, by bioelectrical impedance analysis (BIA), were measured in both groups (icodextrin group: 36 patients, non-icodextrin group: 39 patients) at the 1st (baseline), 12th, 24th and 36th months. There were significant increases in body weight and fat mass during the 36 months after initiation of CAPD. It was found that 78% of 3 years of weight gain occurred during the first year and 88% of weight gain at the end of the first year was fat mass gain. The icodextrin group showed a significantly lower percent of fat mass during the first 36 months (P icodextrin group. There were no significant changes in total body water (TBW), extra cellular fluid (ECF), oedema index and lean body mass (LBM) through comparable daily and ultrafiltration volume (UFV) between the two groups during the initial 3 years. Factors associated with the higher percent of fat mass gain over time on peritoneal dialysis were age, diabetes, gender (female) and non-icodextrin group (all, P icodextrin solution may be a better option to alleviate excessive fat gain over time for patients on PD.
The Ricci flow part IV : long-time solutions and related topics
Chow, Bennett; Glickenstein, David; Isenberg, James
2015-01-01
Ricci flow is a powerful technique using a heat-type equation to deform Riemannian metrics on manifolds to better metrics in the search for geometric decompositions. With the fourth part of their volume on techniques and applications of the theory, the authors discuss long-time solutions of the Ricci flow and related topics. In dimension 3, Perelman completed Hamilton's program to prove Thurston's geometrization conjecture. In higher dimensions the Ricci flow has remarkable properties, which indicates its usefulness to understand relations between the geometry and topology of manifolds. This b
Dandapat, Manika; Mandal, Debabrata
2015-05-01
Alginates are water-soluble polysaccharides that bind metal cations like Ca2+, producing hydrogels. Here, we have determined time-dependent fluorescence Stokes shift of a guest fluorophore to elucidate molecular length-scale local dynamics within alginate-based solutions and hydrogels. We find a major bulk water-like fast response emanating from large water pools interspersed between the polysaccharide chains, together with a minor but significant slow response. The possible origin of the latter is discussed in terms of either water molecules constituting the polysaccharide hydration shells or ion distribution and diffusion around the fluorophore dipole, or microscopic structural inhomogeneity inside the alginate-based media.
Local times for solutions of the complex Ginzburg-Landau equation and the inviscid limit
Shirikyan, Armen
2010-01-01
We consider the behaviour of the distribution for stationary solutions of the complex Ginzburg-Landau equation perturbed by a random force. It was proved earlier that if the random force is proportional to the square root of the viscosity, then the family of stationary measures possesses an accumulation point as the viscosity goes to zero. We show that if $\\mu$ is such point, then the distributions of the L^2 norm and of the energy possess a density with respect to the Lebesgue measure. The proofs are based on It\\^o's formula and some properties of local time for semimartingales.
Linear Scaling Solution of the Time-Dependent Self-Consistent-Field Equations
Directory of Open Access Journals (Sweden)
Matt Challacombe
2014-03-01
Full Text Available A new approach to solving the Time-Dependent Self-Consistent-Field equations is developed based on the double quotient formulation of Tsiper 2001 (J. Phys. B. Dual channel, quasi-independent non-linear optimization of these quotients is found to yield convergence rates approaching those of the best case (single channel Tamm-Dancoff approximation. This formulation is variational with respect to matrix truncation, admitting linear scaling solution of the matrix-eigenvalue problem, which is demonstrated for bulk excitons in the polyphenylene vinylene oligomer and the (4,3 carbon nanotube segment.
Numerical solution of continuous-time DSGE models under Poisson uncertainty
DEFF Research Database (Denmark)
Posch, Olaf; Trimborn, Timo
We propose a simple and powerful method for determining the transition process in continuous-time DSGE models under Poisson uncertainty numerically. The idea is to transform the system of stochastic differential equations into a system of functional differential equations of the retarded type. We...... then use the Waveform Relaxation algorithm to provide a guess of the policy function and solve the resulting system of ordinary differential equations by standard methods and fix-point iteration. Analytical solutions are provided as a benchmark from which our numerical method can be used to explore broader...
Are Time-Domain Self-Force Calculations Contaminated by Jost Solutions?
Jaramillo, Jose Luis; Canizares, Priscilla
2011-01-01
The modeling of the gravitational-wave emission from extreme-mass-ratio inspirals is crucial for their detection and analysis with the future space-based observatory LISA. The inspiral can be described as the action of a local force, the self-force, determined by the gravitational perturbations created by the small object, described as a point mass, on the background geometry. The calculation of the self-force is a challenging task that requires the control of sources of error such as spurious modes or numerical noise. Here we address the question of the possible emergence of a persistent spurious solution in time-domain schemes, referred to as a Jost junk solution in the literature, that may contaminate self-force calculations. Previous studies suggested that Jost solutions are due to the use of zero initial data, which is inconsistent with the singular sources associated with the point mass. However, in this work we show that the specific origin is an inconsistency in the translation of the singular sources...
Real-time Solution via Dynamic Simulation for the Six Degree of Freedom Platform
Directory of Open Access Journals (Sweden)
Lin Lizong
2017-01-01
Full Text Available In order to provide a new way for dynamic simulation experiments, a real-time solution for the six degree of freedom platform was developed. The mathematical model of an improved Six-DOF Stewart platform was used to study positive solutions and inverse solutions. According to the parameters of different platforms, different function signals were selected to generate motion control data by using Visual C++ programming. Motion control card was embedded into industrial computer, data was sent automatically to the control card by the program when the platform ran. The output of the control card was analog voltage, and it was amplified to send to the proportional valve, then the flows of six hydraulic cylinders were controlled by the six proportional valves. So a closed-loop control CNC system was formed. The expected action could be realized by the platform. Experiments have proved that the method is simple, efficient and easy to operate. It can not only accompany the implementation moving of relevant actions in the 3D movie theater, but also provide the signal source for the road spectrum of simulated driving test of the automobile.
Carrault, Guy; Beuchée, Alain; Pladys, Patrick; Senhadji, Lotfi; Hernandez, Alfredo
2009-01-01
International audience; The diagnosis of late onset sepsis in premature infants remains difficult because clinical signs are subtle and non-specific and none of the laboratory tests, including CRP and blood culture, have high predictive accuracy. Heart rate variability (HRV) analysis emerges as a promising diagnostic tool. Entropy and long-range fractal correlation are decreased in premature infants with proven sepsis. Besides this, respiration and its relations to HRV appear to be less. The ...
Time-resolved synchrotron radiation X-ray solution scattering study of DNA melting.
Puigdomenech, J; Perez-Grau, L; Porta, J; Vega, M C; Sicre, P; Koch, M H
1989-09-01
Time resolved x-ray solution scattering measurements were made during thermal denaturation of DNA from various sources in the temperature range of 20-90 degrees C. Preliminary results on the influence of fragment length, ionic strength, and origin of the DNA on the time course of the scattering are described. Interpretation is based on model calculations of the scattering patterns. The results indicate that, for long DNA fragments at very low ionic strength, the melting process is a continuous phenomenon over the whole temperature range. It is accompanied by a progressive decrease of the radius of gyration of the cross section and of the mass per unit length. For short fragments of 146 base pair nucleosomal core DNA, stiffening of the DNA appears to precede a sharp melting transition.
Virtual instrumentation and real-time executive dashboards. Solutions for health care systems.
Rosow, Eric; Adam, Joseph; Coulombe, Kathleen; Race, Kathleen; Anderson, Rhonda
2003-01-01
Successful organizations have the ability to measure and act on key indicators and events in real time. By leveraging the power of virtual instrumentation and open architecture standards, multidimensional executive dashboards can empower health care organizations to make better and faster data-driven decisions. This article will highlight how user-defined virtual instruments and dashboards can connect to hospital information systems (e.g., admissions/discharge/transfer systems, patient monitoring networks) and use statistical process control to "visualize" information and make timely, data-driven decisions. The case studies described will illustrate enterprisewide solutions for: bed management and census control, operational management, data mining and business intelligence applications, and clinical applications (physiological data acquisition and wound measurement and analysis).
Directory of Open Access Journals (Sweden)
Kurt Weissgerber
2011-01-01
Full Text Available The underlying goal of a competing agent in a discrete real-time strategy (RTS game is to defeat an adversary. Strategic agents or participants must define an a priori plan to maneuver their resources in order to destroy the adversary and the adversary's resources as well as secure physical regions of the environment. This a priori plan can be generated by leveraging collected historical knowledge about the environment. This knowledge is then employed in the generation of a classification model for real-time decision-making in the RTS domain. The best way to generate a classification model for a complex problem domain depends on the characteristics of the solution space. An experimental method to determine solution space (search landscape characteristics is through analysis of historical algorithm performance for solving the specific problem. We select a deterministic search technique and a stochastic search method for a priori classification model generation. These approaches are designed, implemented, and tested for a specific complex RTS game, Bos Wars. Their performance allows us to draw various conclusions about applying a competing agent in complex search landscapes associated with RTS games.
Real-time in situ probing of high-temperature quantum dots solution synthesis.
Abécassis, Benjamin; Bouet, Cécile; Garnero, Cyril; Constantin, Doru; Lequeux, Nicolas; Ithurria, Sandrine; Dubertret, Benoit; Pauw, Brian Richard; Pontoni, Diego
2015-04-08
Understanding the formation mechanism of colloidal nanocrystals is of paramount importance in order to design new nanostructures and synthesize them in a predictive fashion. However, reliable data on the pathways leading from molecular precursors to nanocrystals are not available yet. We used synchrotron-based time-resolved in situ small and wide-angle X-ray scattering to experimentally monitor the formation of CdSe quantum dots synthesized in solution through the heating up of precursors in octadecene at 240 °C. Our experiment yields a complete movie of the structure of the solution from the self-assembly of the precursors to the formation of the quantum dots. We show that the initial cadmium precursor lamellar structure melts into small micelles at 100 °C and that the first CdSe nuclei appear at 218.7 °C. The size distributions and concentration in nanocrystals are measured in a quantitative fashion as a function of time. We show that a short nucleation burst lasting 30 s is followed by a slow decrease of nanoparticle concentration. The rate-limiting process of the quantum dot formation is found to be the thermal activation of selenium.
Analytical solution for beam with time-dependent boundary conditions versus response spectrum
Energy Technology Data Exchange (ETDEWEB)
Gou, P.F.; Panahi, K.K. [GE Nuclear Energy, San Jose, CA (United States)
2001-07-01
This paper studies the responses of a uniform simple beam for which the supports are subjected to time-dependent conditions. Analytical solution in terms of series was presented for two cases: (1) Two supports of a simple beam are subjected to a harmonic motion, and (2) One of the two supports is stationary while the other is subjected to a harmonic motion. The results of the analytical solution were investigated and compared with the results of conventional response spectrum method using the beam finite element model. One of the applications of the results presented in this paper can be used to assess the adequacy and accuracy of the engineering approaches such as response spectra methods. It has been found that, when the excitation frequency equals the fundamental frequency of the beam, the results from response spectrum method are in good agreement with the exact calculation. The effects of initial conditions on the responses are also examined. It seems that the non-zero initial velocity has pronounced effects on the displacement time histories but it has no effect on the maximum accelerations. (author)
Doubly Exponential Solution for Randomized Load Balancing Models with General Service Times
Li, Quan-Lin
2010-01-01
In this paper, we provide a novel and simple approach to study the supermarket model with general service times. This approach is based on the supplementary variable method used in analyzing stochastic models extensively. We organize an infinite-size system of integral-differential equations by means of the density dependent jump Markov process, and obtain a close-form solution: doubly exponential structure, for the fixed point satisfying the system of nonlinear equations, which is always a key in the study of supermarket models. The fixed point is decomposited into two groups of information under a product form: the arrival information and the service information. based on this, we indicate two important observations: the fixed point for the supermarket model is different from the tail of stationary queue length distribution for the ordinary M/G/1 queue, and the doubly exponential solution to the fixed point can extensively exist even if the service time distribution is heavy-tailed. Furthermore, we analyze ...
Cost-Effective Video Filtering Solution for Real-Time Vision Systems
Directory of Open Access Journals (Sweden)
Karl Martin
2005-08-01
Full Text Available This paper presents an efficient video filtering scheme and its implementation in a field-programmable logic device (FPLD. Since the proposed nonlinear, spatiotemporal filtering scheme is based on order statistics, its efficient implementation benefits from a bit-serial realization. The utilization of both the spatial and temporal correlation characteristics of the processed video significantly increases the computational demands on this solution, and thus, implementation becomes a significant challenge. Simulation studies reported in this paper indicate that the proposed pipelined bit-serial FPLD filtering solution can achieve speeds of up to 97.6 Mpixels/s and consumes 1700 to 2700 logic cells for the speed-optimized and area-optimized versions, respectively. Thus, the filter area represents only 6.6 to 10.5% of the Altera STRATIX EP1S25 device available on the Altera Stratix DSP evaluation board, which has been used to implement a prototype of the entire real-time vision system. As such, the proposed adaptive video filtering scheme is both practical and attractive for real-time machine vision and surveillance systems as well as conventional video and multimedia applications.
Cui, Yi-an; Liu, Lanbo; Zhu, Xiaoxiong
2017-08-01
Monitoring the extent and evolution of contaminant plumes in local and regional groundwater systems from existing landfills is critical in contamination control and remediation. The self-potential survey is an efficient and economical nondestructive geophysical technique that can be used to investigate underground contaminant plumes. Based on the unscented transform, we have built a Kalman filtering cycle to conduct time-lapse data assimilation for monitoring the transport of solute based on the solute transport experiment using a bench-scale physical model. The data assimilation was formed by modeling the evolution based on the random walk model and observation correcting based on the self-potential forward. Thus, monitoring self-potential data can be inverted by the data assimilation technique. As a result, we can reconstruct the dynamic process of the contaminant plume instead of using traditional frame-to-frame static inversion, which may cause inversion artifacts. The data assimilation inversion algorithm was evaluated through noise-added synthetic time-lapse self-potential data. The result of the numerical experiment shows validity, accuracy and tolerance to the noise of the dynamic inversion. To validate the proposed algorithm, we conducted a scaled-down sandbox self-potential observation experiment to generate time-lapse data that closely mimics the real-world contaminant monitoring setup. The results of physical experiments support the idea that the data assimilation method is a potentially useful approach for characterizing the transport of contamination plumes using the unscented Kalman filter (UKF) data assimilation technique applied to field time-lapse self-potential data.
Ohyanagi, Toshio; Sengoku, Yasuhito
2010-02-01
This article presents a new solution for measuring accurate reaction time (SMART) to visual stimuli. The SMART is a USB device realized with a Cypress Programmable System-on-Chip (PSoC) mixed-signal array programmable microcontroller. A brief overview of the hardware and firmware of the PSoC is provided, together with the results of three experiments. In Experiment 1, we investigated the timing accuracy of the SMART in measuring reaction time (RT) under different conditions of operating systems (OSs; Windows XP or Vista) and monitor displays (a CRT or an LCD). The results indicated that the timing error in measuring RT by the SMART was less than 2 msec, on average, under all combinations of OS and display and that the SMART was tolerant to jitter and noise. In Experiment 2, we tested the SMART with 8 participants. The results indicated that there was no significant difference among RTs obtained with the SMART under the different conditions of OS and display. In Experiment 3, we used Microsoft (MS) PowerPoint to present visual stimuli on the display. We found no significant difference in RTs obtained using MS DirectX technology versus using the PowerPoint file with the SMART. We are certain that the SMART is a simple and practical solution for measuring RTs accurately. Although there are some restrictions in using the SMART with RT paradigms, the SMART is capable of providing both researchers and health professionals working in clinical settings with new ways of using RT paradigms in their work.
The short-time intramolecular dynamics of solutes in liquids. II. Vibrational population relaxation
Goodyear, Grant; Stratt, Richard M.
1997-08-01
Events such as the vibrational relaxation of a solute are often well described by writing an effective equation of motion—a generalized Langevin equation—which expresses the surrounding medium's influence on the intramolecular dynamics in terms of a friction and a fluctuating force acting on the solute. These quantities, though, can be obtained from the instantaneous normal modes (INMs) of the system when the relaxation takes place in a fluid, suggesting that we should be able to analyze in some detail the solvent motions driving the relaxation, at least for short times. In this paper we show that this promise can indeed be realized for the specific case of a vibrating diatomic molecule dissolved in an atomic solvent. Despite the relatively long times typical of vibrational population relaxation, it turns out that understanding the behavior of the vibrational friction at the short times appropriate to INMs (a few hundred femtoseconds) often suffices to predict T1 times. We use this observation to probe the dependence of these relaxation rates on thermodynamic conditions and to look at the molecular mechanisms underlying the process. We find that raising the temperature at any given density or raising the density at any given temperature will invariably increase the rate of energy relaxation. However, since these two trends may be in conflict in a typical constant-pressure laboratory experiment, we also find that it is possible to make sense of the "anomalous" inverted temperature dependence recently seen experimentally. We find, as well, that the INM theory—which has no explicit collisions built into it—predicts exactly the same density dependence as the venerable independent-binary-collision (IBC) theory (an intriguing result in view of recent claims that experimental observations of this kind of dependence provide support for the IBC theory). The actual mechanisms behind vibrational population relaxation are revealed by looking in detail at the
A software solution for recording circadian oscillator features in time-lapse live cell microscopy
Directory of Open Access Journals (Sweden)
Salmon Patrick
2010-07-01
Full Text Available Abstract Background Fluorescent and bioluminescent time-lapse microscopy approaches have been successfully used to investigate molecular mechanisms underlying the mammalian circadian oscillator at the single cell level. However, most of the available software and common methods based on intensity-threshold segmentation and frame-to-frame tracking are not applicable in these experiments. This is due to cell movement and dramatic changes in the fluorescent/bioluminescent reporter protein during the circadian cycle, with the lowest expression level very close to the background intensity. At present, the standard approach to analyze data sets obtained from time lapse microscopy is either manual tracking or application of generic image-processing software/dedicated tracking software. To our knowledge, these existing software solutions for manual and automatic tracking have strong limitations in tracking individual cells if their plane shifts. Results In an attempt to improve existing methodology of time-lapse tracking of a large number of moving cells, we have developed a semi-automatic software package. It extracts the trajectory of the cells by tracking theirs displacements, makes the delineation of cell nucleus or whole cell, and finally yields measurements of various features, like reporter protein expression level or cell displacement. As an example, we present here single cell circadian pattern and motility analysis of NIH3T3 mouse fibroblasts expressing a fluorescent circadian reporter protein. Using Circadian Gene Express plugin, we performed fast and nonbiased analysis of large fluorescent time lapse microscopy datasets. Conclusions Our software solution, Circadian Gene Express (CGE, is easy to use and allows precise and semi-automatic tracking of moving cells over longer period of time. In spite of significant circadian variations in protein expression with extremely low expression levels at the valley phase, CGE allows accurate and
Finite Difference Solution of Response Time Delay of Magneto-rhelological Damper
Institute of Scientific and Technical Information of China (English)
ZOU Mingsong; HOU Baolin
2009-01-01
Magneto-rhelological(MR) dampers are devices that employ rheological fluids to modify their mechanical properties. Their mechanical simplicity, high dynamic range, lower power requirements, large force capacity, robustness and safe manner of operation in cases of failure have made them attractive devices for semi-active real-time control in civil, aerospace and automotive applications. Time response characteristic is one of the most important technical performances of MR dampers, and response time directly affects the control frequency, application range and the actual effect of MR dampers. In this study, one kind of finite difference solution for predicting the response time of magneto-rheological dampers from "off-state" to "on-state" is put forward. A laminar flow model is used to describe the flow in the MR valve, and a bi-viscous fluid flow model is utilized to describe the relationship of shear stress and shear rate of MR fluid. An explicit difference format is used to discretize the Novior-Stoks equation, and stability condition of this algorithm is built by Von-Neumann stability criterion. The pressure gradient along the flow duct is solved by a dichotomy algorithm with iteration, and the changing curve of the damping force versus time of MR damper is obtained as well. According to the abovementioned numerical algorithm, the damping forces versus time curves from "off-state" to "on-state" of a cylindrical piston type MR damper are computed. Moreover, the MR damper is installed in a material test system(MTS), the magnetic field in the wire circles of the MR damper is "triggered" when the MR damper is imposed to do a constant speed motion, and the damping force curves are recorded. The comparison between numerical results and experimental results indicates that this finite difference algorithm can be used to estimate the response time delay of MR dampers.
Traversa, Fabio L; Di Ventra, Massimiliano
2017-02-01
We introduce a class of digital machines, we name Digital Memcomputing Machines, (DMMs) able to solve a wide range of problems including Non-deterministic Polynomial (NP) ones with polynomial resources (in time, space, and energy). An abstract DMM with this power must satisfy a set of compatible mathematical constraints underlying its practical realization. We prove this by making a connection with the dynamical systems theory. This leads us to a set of physical constraints for poly-resource resolvability. Once the mathematical requirements have been assessed, we propose a practical scheme to solve the above class of problems based on the novel concept of self-organizing logic gates and circuits (SOLCs). These are logic gates and circuits able to accept input signals from any terminal, without distinction between conventional input and output terminals. They can solve boolean problems by self-organizing into their solution. They can be fabricated either with circuit elements with memory (such as memristors) and/or standard MOS technology. Using tools of functional analysis, we prove mathematically the following constraints for the poly-resource resolvability: (i) SOLCs possess a global attractor; (ii) their only equilibrium points are the solutions of the problems to solve; (iii) the system converges exponentially fast to the solutions; (iv) the equilibrium convergence rate scales at most polynomially with input size. We finally provide arguments that periodic orbits and strange attractors cannot coexist with equilibria. As examples, we show how to solve the prime factorization and the search version of the NP-complete subset-sum problem. Since DMMs map integers into integers, they are robust against noise and hence scalable. We finally discuss the implications of the DMM realization through SOLCs to the NP = P question related to constraints of poly-resources resolvability.
Traversa, Fabio L.; Di Ventra, Massimiliano
2017-02-01
We introduce a class of digital machines, we name Digital Memcomputing Machines, (DMMs) able to solve a wide range of problems including Non-deterministic Polynomial (NP) ones with polynomial resources (in time, space, and energy). An abstract DMM with this power must satisfy a set of compatible mathematical constraints underlying its practical realization. We prove this by making a connection with the dynamical systems theory. This leads us to a set of physical constraints for poly-resource resolvability. Once the mathematical requirements have been assessed, we propose a practical scheme to solve the above class of problems based on the novel concept of self-organizing logic gates and circuits (SOLCs). These are logic gates and circuits able to accept input signals from any terminal, without distinction between conventional input and output terminals. They can solve boolean problems by self-organizing into their solution. They can be fabricated either with circuit elements with memory (such as memristors) and/or standard MOS technology. Using tools of functional analysis, we prove mathematically the following constraints for the poly-resource resolvability: (i) SOLCs possess a global attractor; (ii) their only equilibrium points are the solutions of the problems to solve; (iii) the system converges exponentially fast to the solutions; (iv) the equilibrium convergence rate scales at most polynomially with input size. We finally provide arguments that periodic orbits and strange attractors cannot coexist with equilibria. As examples, we show how to solve the prime factorization and the search version of the NP-complete subset-sum problem. Since DMMs map integers into integers, they are robust against noise and hence scalable. We finally discuss the implications of the DMM realization through SOLCs to the NP = P question related to constraints of poly-resources resolvability.
Fring, Andreas
2016-01-01
We propose a procedure to obtain exact analytical solutions to the time-dependent Schr\\"{o}dinger equations involving explicit time-dependent Hermitian Hamitonians from solutions to time-independent non-Hermitian Hamiltonian systems and the time-dependent Dyson relation together with the time-dependent quasi-Hermiticity relation. We illustrate the working of this method for a simple Hermitian Rabi-type model by relating it to a non-Hermitian time-independent system corresponding to the one-site lattice Yang-Lee model.
Fring, Andreas; Frith, Thomas
2017-01-01
We propose a procedure to obtain exact analytical solutions to the time-dependent Schrödinger equations involving explicit time-dependent Hermitian Hamiltonians from solutions to time-independent non-Hermitian Hamiltonian systems and the time-dependent Dyson relation, together with the time-dependent quasi-Hermiticity relation. We illustrate the working of this method for a simple Hermitian Rabi-type model by relating it to a non-Hermitian time-independent system corresponding to the one-site lattice Yang-Lee model.
The Existence and Long-Time Behavior of Weak Solution to Bipolar Quantum Drift-Diffusion Model
Institute of Scientific and Technical Information of China (English)
Xiuqing CHEN; Li CHEN; Huaiyu JIAN
2007-01-01
The authors study the existence and long-time behavior of weak solutions to the bipolar transient quantum drift-diffusion model, a fourth order parabolic system. Using semi-discretization in time and entropy estimate, the authors get the global existence of nonnegative weak solutions to the one-dimensional model with nonnegative initial and homogenous Neumann (or periodic) boundary conditions. Furthermore, by a logarithmic Sobolev inequality, it is proved that the periodic weak solution exponentially approaches its mean value as time increases to infinity.
DEFF Research Database (Denmark)
For solving partial differential equations (or distributed dynamic systems), the method of lines (MOL) and the space-time conservation element and solution element (CE/SE) method are compared in terms of computational efficiency, solution accuracy and stability. Several representative examples...... including convection-difmsion-reaction PDEs are numerically solved using the two methods on the same spatial grid. Even though the CE/SE method uses a simple stencil structure and is developed on a simple mathematical basis (i.e., Gauss' divergence theorem), accurate and computationally-efficient solutions....... It is concluded that the CE/SE method is adequate to capturing shocks in PDEs but for diffusion-dominated stiff PDEs, the MOL with an ODE time integrator is complementary to the CE/SE method....
Directory of Open Access Journals (Sweden)
Yong-Jin Yoon
2015-03-01
Full Text Available Global Positioning System and Inertial Navigation System can be used to determine position and velocity. A Global Positioning System module is able to accurately determine position without sensor drift, but its usage is limited in heavily urbanized environments and heavy vegetation. While high-cost tactical-grade Inertial Navigation System can determine position accurately, low-cost micro-electro-mechanical system Inertial Navigation System sensors are plagued by significant errors. Global Positioning System is coupled with Inertial Navigation System to correct the errors, while Inertial Navigation System itself can be used to provide navigation solution during a Global Positioning System outage. Data from Global Positioning System and Inertial Navigation System can be integrated by extensive Kalman filtering, using loosely coupled integration architecture to provide navigation solutions. In this study, real-time low-cost loosely coupled micro-electro-mechanical system Inertial Navigation System/Global Positioning System sensors have been used for pedestrian navigation. Trial runs of Global Positioning System outages have been conducted to determine the accuracy of the system described. The micro-electro-mechanical system Inertial Navigation System/Global Positioning System can successfully project a trajectory during a Global Positioning System outage and produces a root mean square error of 9.35 m in latitude direction and 10.8 m in longitude direction. This technology is very suitable for visually impaired pedestrians.
Becker, P A; Le, T
2006-01-01
Stochastic acceleration of charged particles due to interactions with magnetohydrodynamic (MHD) plasma waves is the dominant process leading to the formation of the high-energy electron and ion distributions in a variety of astrophysical systems. Collisions with the waves influence both the energization and the spatial transport of the particles, and therefore it is important to treat these two aspects of the problem in a self-consistent manner. We solve the representative Fokker-Planck equation to obtain a new, closed-form solution for the time-dependent Green's function describing the acceleration and escape of relativistic ions interacting with Alfven or fast-mode waves characterized by momentum diffusion coefficient $D(p)\\propto p^q$ and mean particle escape timescale $t_esc(p) \\propto p^{q-2}$, where $p$ is the particle momentum and $q$ is the power-law index of the MHD wave spectrum. In particular, we obtain solutions for the momentum distribution of the ions in the plasma and also for the momentum dist...
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...
Wani, Naveel; Maqbool, Bari; Iqbal, Naseer; Misra, Ranjeev
2016-07-01
X-ray binaries and AGNs are powered by accretion discs around compact objects, where the x-rays are emitted from the inner regions and uv emission arise from the relatively cooler outer parts. There has been an increasing evidence that the variability of the x-rays in different timescales is caused by stochastic fluctuations in the accretion disc at different radii. These fluctuations although arise in the outer parts of the disc but propagate inwards to give rise to x-ray variability and hence provides a natural connection between the x-ray and uv variability. There are analytical expressions to qualitatively understand the effect of these stochastic variabilities, but quantitative predictions are only possible by a detailed hydrodynamical study of the global time dependent solution of standard accretion disc. We have developed numerical efficient code (to incorporate all these effects), which considers gas pressure dominated solutions and stochastic fluctuations with the inclusion of boundary effect of the last stable orbit.
Kulaksız, Tuğba Nilay; Koşar, Şükran Nazan; Bulut, Suleyman; Güzel, Yasemin; Willems, Marcus Elisabeth Theodorus; Hazir, Tahir; Turnagöl, Hüseyin Hüsrev
2016-05-09
The carbohydrate (CHO) concentration of a mouth rinsing solution might influence the CHO sensing receptors in the mouth, with consequent activation of brain regions involved in reward, motivation and regulation of motor activity. The purpose of the present study was to examine the effects of maltodextrin mouth rinsing with different concentrations (3%, 6% and 12%) after an overnight fast on a 20 km cycling time trial performance. Nine recreationally active, healthy males (age: 24 ± 2 years; V ˙ O 2 m a x : 47 ± 5 mL·kg(-1)·min(-1)) participated in this study. A double-blind, placebo-controlled randomized study was conducted. Participants mouth-rinsed every 2.5 km for 5 s. Maltodextrin mouth rinse with concentrations of 3%, 6% or 12% did not change time to complete the time trial and power output compared to placebo (p > 0.05). Time trial completion times were 40.2 ± 4.0, 40.1 ± 3.9, 40.1 ± 4.4, and 39.3 ± 4.2 min and power output 205 ± 22, 206 ± 25, 210 ± 24, and 205 ± 23 W for placebo, 3%, 6%, and 12% maltodextrin conditions, respectively. Heart rate, lactate, glucose, and rating of perceived exertion did not differ between trials (p > 0.05). In conclusion, mouth rinsing with different maltodextrin concentrations after an overnight fast did not affect the physiological responses and performance during a 20 km cycling time trial in recreationally active males.
Kulaksız, Tuğba Nilay; Koşar, Şükran Nazan; Bulut, Suleyman; Güzel, Yasemin; Willems, Marcus Elisabeth Theodorus; Hazir, Tahir; Turnagöl, Hüseyin Hüsrev
2016-01-01
The carbohydrate (CHO) concentration of a mouth rinsing solution might influence the CHO sensing receptors in the mouth, with consequent activation of brain regions involved in reward, motivation and regulation of motor activity. The purpose of the present study was to examine the effects of maltodextrin mouth rinsing with different concentrations (3%, 6% and 12%) after an overnight fast on a 20 km cycling time trial performance. Nine recreationally active, healthy males (age: 24 ± 2 years; V˙O2max: 47 ± 5 mL·kg−1·min−1) participated in this study. A double-blind, placebo-controlled randomized study was conducted. Participants mouth-rinsed every 2.5 km for 5 s. Maltodextrin mouth rinse with concentrations of 3%, 6% or 12% did not change time to complete the time trial and power output compared to placebo (p > 0.05). Time trial completion times were 40.2 ± 4.0, 40.1 ± 3.9, 40.1 ± 4.4, and 39.3 ± 4.2 min and power output 205 ± 22, 206 ± 25, 210 ± 24, and 205 ± 23 W for placebo, 3%, 6%, and 12% maltodextrin conditions, respectively. Heart rate, lactate, glucose, and rating of perceived exertion did not differ between trials (p > 0.05). In conclusion, mouth rinsing with different maltodextrin concentrations after an overnight fast did not affect the physiological responses and performance during a 20 km cycling time trial in recreationally active males. PMID:27171108
Directory of Open Access Journals (Sweden)
Tuğba Nilay Kulaksız
2016-05-01
Full Text Available The carbohydrate (CHO concentration of a mouth rinsing solution might influence the CHO sensing receptors in the mouth, with consequent activation of brain regions involved in reward, motivation and regulation of motor activity. The purpose of the present study was to examine the effects of maltodextrin mouth rinsing with different concentrations (3%, 6% and 12% after an overnight fast on a 20 km cycling time trial performance. Nine recreationally active, healthy males (age: 24 ± 2 years; V ˙ O 2 m a x : 47 ± 5 mL·kg−1·min−1 participated in this study. A double-blind, placebo-controlled randomized study was conducted. Participants mouth-rinsed every 2.5 km for 5 s. Maltodextrin mouth rinse with concentrations of 3%, 6% or 12% did not change time to complete the time trial and power output compared to placebo (p > 0.05. Time trial completion times were 40.2 ± 4.0, 40.1 ± 3.9, 40.1 ± 4.4, and 39.3 ± 4.2 min and power output 205 ± 22, 206 ± 25, 210 ± 24, and 205 ± 23 W for placebo, 3%, 6%, and 12% maltodextrin conditions, respectively. Heart rate, lactate, glucose, and rating of perceived exertion did not differ between trials (p > 0.05. In conclusion, mouth rinsing with different maltodextrin concentrations after an overnight fast did not affect the physiological responses and performance during a 20 km cycling time trial in recreationally active males.
Directory of Open Access Journals (Sweden)
J.-S. Chen
2011-04-01
Full Text Available This study presents a generalized analytical solution for one-dimensional solute transport in finite spatial domain subject to arbitrary time-dependent inlet boundary condition. The governing equation includes terms accounting for advection, hydrodynamic dispersion, linear equilibrium sorption and first order decay processes. The generalized analytical solution is derived by using the Laplace transform with respect to time and the generalized integral transform technique with respect to the spatial coordinate. Several special cases are presented and compared to illustrate the robustness of the derived generalized analytical solution. Result shows an excellent agreement. The analytical solutions of the special cases derived in this study have practical applications. Moreover, the derived generalized solution which consists an integral representation is evaluated by the numerical integration to extend its usage. The developed generalized solution offers a convenient tool for further development of analytical solution of specified time-dependent inlet boundary conditions or numerical evaluation of the concentration field for arbitrary time-dependent inlet boundary problem.
Chruściel, Piotr T.; Delay, Erwann
2017-08-01
We construct infinite-dimensional families of non-singular static space-times, solutions of the vacuum Einstein-Maxwell equations with a negative cosmological constant. The families include an infinite-dimensional family of solutions with the usual AdS conformal structure at conformal infinity.
Analytical Solutions of the Space-Time Fractional Derivative of Advection Dispersion Equation
Directory of Open Access Journals (Sweden)
Abdon Atangana
2013-01-01
Full Text Available Fractional advection-dispersion equations are used in groundwater hydrology to model the transport of passive tracers carried by fluid flow in porous medium. A space-time fractional advection-dispersion equation (FADE is a generalization of the classical ADE in which the first-order space derivative is replaced with Caputo or Riemann-Liouville derivative of order , and the second-order space derivative is replaced with the Caputo or the Riemann-Liouville fractional derivative of order . We derive the solution of the new equation in terms of Mittag-Leffler functions using Laplace transfrom. Some examples are given. The results from comparison let no doubt that the FADE is better in prediction than ADE.
Extensional Relaxation Times and Pinch-off Dynamics of Dilute Polymer Solutions
Dinic, Jelena; Zhang, Yiran; Jimenez, Leidy; Sharma, Vivek
2015-11-01
We show that visualization and analysis of capillary-driven thinning and pinch-off dynamics of the columnar neck in an asymmetric liquid bridge created by dripping-onto-substrate can be used for characterizing the extensional rheology of complex fluids. Using a particular example of dilute, aqueous PEO solutions, we show the measurement of both the extensional relaxation time and extensional viscosity of weakly elastic, polymeric complex fluids with low shear viscosity ηsessile drop to a nozzle is detected optically, and the extensional response for viscoelastic fluids is characterized by analyzing their elastocapillary self-thinning, we refer to this technique as optically-detected elastocapillary self-thinning dripping-onto-substrate (ODES-DOS) extensional rheometry.
Real-time solution of nonlinear potential flow equations for lifting rotors
Directory of Open Access Journals (Sweden)
Jianzhe HUANG
2017-06-01
Full Text Available Analysis of rotorcraft dynamics requires solution of the rotor induced flow field. Often, the appropriate model to be used for induced flow is nonlinear potential flow theory (which is the basis of vortex-lattice methods. These nonlinear potential flow equations sometimes must be solved in real time––such as for real-time flight simulation, when observers are needed for controllers, or in preliminary design computations. In this paper, the major effects of nonlinearities on induced flow are studied for lifting rotors in low-speed flight and hover. The approach is to use a nonlinear state-space model of the induced flow based on a Galerkin treatment of the potential flow equations.
MARKOV: A methodology for the solution of infinite time horizon MARKOV decision processes
Williams, B.K.
1988-01-01
Algorithms are described for determining optimal policies for finite state, finite action, infinite discrete time horizon Markov decision processes. Both value-improvement and policy-improvement techniques are used in the algorithms. Computing procedures are also described. The algorithms are appropriate for processes that are either finite or infinite, deterministic or stochastic, discounted or undiscounted, in any meaningful combination of these features. Computing procedures are described in terms of initial data processing, bound improvements, process reduction, and testing and solution. Application of the methodology is illustrated with an example involving natural resource management. Management implications of certain hypothesized relationships between mallard survival and harvest rates are addressed by applying the optimality procedures to mallard population models.
Multiple periodic solutions for a discrete time model of plankton allelopathy
Zhang Jianbao; Fang Hui
2006-01-01
We study a discrete time model of the growth of two species of plankton with competitive and allelopathic effects on each other N1(k+1) = N1(k)exp{r1(k)-a11(k)N1(k)-a12(k)N2(k)-b1(k)N1(k)N2(k)}, N2(k+1) = N2(k)exp{r2(k)-a21(k)N2(k)-b2(k)N1(k)N1(k)N2(k)}. A set of sufficient conditions is obtained for the existence of multiple positive periodic solutions for this model. The approach is based on Mawhin's continuation theorem of coincidence degree theory as well as some a priori estimates. Some...
A coupled $2\\times2$D Babcock-Leighton solar dynamo model. II. Reference dynamo solutions
Lemerle, Alexandre
2016-01-01
In this paper we complete the presentation of a new hybrid $2\\times2$D flux transport dynamo (FTD) model of the solar cycle based on the Babcock-Leighton mechanism of poloidal magnetic field regeneration via the surface decay of bipolar magnetic regions (BMRs). This hybrid model is constructed by allowing the surface flux transport (SFT) simulation described in Lemerle et al. 2015 to provide the poloidal source term to an axisymmetric FTD simulation defined in a meridional plane, which in turn generates the BMRs required by the SFT. A key aspect of this coupling is the definition of an emergence function describing the probability of BMR emergence as a function of the spatial distribution of the internal axisymmetric magnetic field. We use a genetic algorithm to calibrate this function, together with other model parameters, against observed cycle 21 emergence data. We present a reference dynamo solution reproducing many solar cycle characteristics, including good hemispheric coupling, phase relationship betwe...
Lie Symmetries, Conservation Laws and Explicit Solutions for Time Fractional Rosenau–Haynam Equation
Qin, Chun-Yan; Tian, Shou-Fu; Wang, Xiu-Bin; Zhang, Tian-Tian
2017-02-01
Under investigation in this paper is the invariance properties of the time fractional Rosenau-Haynam equation, which can be used to describe the formation of patterns in liquid drops. By using the Lie group analysis method, the vector fields and symmetry reductions of the equation are derived, respectively. Moreover, based on the power series theory, a kind of explicit power series solutions for the equation are well constructed with a detailed derivation. Finally, by using the new conservation theorem, two kinds of conservation laws of the equation are well constructed with a detailed derivation. Supported by the Fundamental Research Fund for Talents Cultivation Project of the China University of Mining and Technology under Grant No. YC150003
CORSA: An Open Solution for Social Oriented Real-time Ride Sharing
Directory of Open Access Journals (Sweden)
Bonarrigo Simone
2015-01-01
Full Text Available The combination of the interest in environmental questions on one hand and the massive use of web based social networks on the other recently led to a revival of carpooling. In particular, the exploitation of social networks promotes the information spreading for an effective service (e.g. reducing the lack of confidence among users and endorses carpooling companies via viral marketing, finally acting as a basis for trust based users recommendation system In this work we outline CORSA, an open source solution for a real time ride sharing (RTRS carpooling service that endorses the role of social networks by using them as a conveying scenario for the virtual credits reward mechanism CORSA is based on.
Multiple periodic solutions for a discrete time model of plankton allelopathy
Zhang Jianbao; Fang Hui
2006-01-01
We study a discrete time model of the growth of two species of plankton with competitive and allelopathic effects on each other N1(k+1) = N1(k)exp{r1(k)-a11(k)N1(k)-a12(k)N2(k)-b1(k)N1(k)N2(k)}, N2(k+1) = N2(k)exp{r2(k)-a21(k)N2(k)-b2(k)N1(k)N1(k)N2(k)}. A set of sufficient conditions is obtained for the existence of multiple positive periodic solutions for this model. The approach is based on Mawhin's continuation theorem of coincidence degree theory as well as some a priori estimates. Some...
Sergey, S. Golik; Alexey, A. Ilyin; Michael, Yu. Babiy; Yulia, S. Biryukova; Vladimir, V. Lisitsa; Oleg, A. Bukin
2015-11-01
The influence of the energy of femtosecond laser pulses on the intensity of Fe I (371.99 nm) emission line and the continuous spectrum of the plasma generated on the surface of Fe3+ water solution by a Ti: sapphire laser radiation with pulse duration laser pulse energy. It is found that an increase of laser pulse energy insignificantly affects on LOD in the time-resolved LIBS and leads to a slight improvement of the limit of detection. supported by the Russian Science Foundation (agreement #14-50-00034) (measurements of limit of detection), Russian Foundation for Basic Research (NK 15-32-20878/15) obtained in the frame of “Organization of Scientific Research” in the Far Eastern Federal University supported by Ministry of Education and Science of Russian Federation
Existence of positive solutions for semipositone dynamic system on time scales
Directory of Open Access Journals (Sweden)
You-Wei Zhang
2008-08-01
Full Text Available In this paper, we study the following semipositone dynamic system on time scales $$displaylines{ -x^{DeltaDelta}(t=f(t,y+p(t, quad tin(0,T_{mathbb{T}},cr -y^{DeltaDelta}(t=g(t,x, quad tin(0,T_{mathbb{T}},cr x(0=x(sigma^{2}(T=0, cr alpha{y(0}-eta{y^{Delta}{(0}}= gamma{y(sigma(T}+delta{y^{Delta}(sigma(T}=0. }$$ Using fixed point index theory, we show the existence of at least one positive solution. The interesting point is the that nonlinear term is allowed to change sign and may tend to negative infinity.
On solute residence time in the storage zones of small streams - experimental study and scaling law
Schmid, Bernhard
2013-04-01
Transient storage has a major influence on solute transport in streams, on biogeochemical cycling, water quality and on the functioning of aquatic ecosystems. The first part of the research reported here focuses on surface transient storage (STS) zones between groins along small streams. Such groins are used to protect banks, but also to increase habitat diversity and are, thus, not restricted to large rivers. Repeated tracer dilution experiments on the Mödlingbach, a small stream in Austria some 30 km south of Vienna, have been analyzed to determine the solute residence time between groins and to characterize the exchange processes between dead zones and main stream. Pairs of related breakthrough curves were measured in main stream and storage zones, resp., and used subsequently to estimate the solute residence time in the surface dead zones under study. Following previous work (Weitbrecht et al., 2008; Jackson et al., 2012) these residence times were, in turn, expressed as T = -W-.hD- k ?u hE (1) with W denoting groin length, u main stream flow velocity, hD mean water depth between the groins and hE depth at the interface dead zone - main stream. Coefficient k, finally, is thought to depend on a type of hydraulic radius, RD = W.L/(W+L), with L denoting the distance between the groins, measured in main flow direction. Using both the Mödlingbach STS zone data and the results of the aforementioned study (Weitbrecht et al., 2008) the following regression equation was derived (hS denotes main stream water depth): k = 0.00282? RD + 0.00802 hS (2) The second part of this research focuses on the dependency of solute residence time on flow rate, which is important for an improved understanding of longitudinal solute transport in streams and for the application of mathematical models. The scaling law proposed here is based on a physics-related theory combined with extensive data sets available form a decade of stream tracer experiments on the Mödlingbach stream
Gouweleeuw, B.; Kvas, A.; Gruber, C.; Schumacher, M.; Mayer-Gürr, T.; Flechtner, F.; Kusche, J.; Guntner, A.
2016-12-01
Water storage anomalies from the Gravity Recovery and Climate Experiment (GRACE) satellite mission (2002-present) have been shown to be a unique descriptor of large-scale hydrological extreme events. However, possibly due to its coarse temporal (weekly to monthly), spatial (> 150.000 km2) resolution and the latency of standard products of about 2 months, the comprehensive information from GRACE on total water storage variations has rarely been evaluated for near-real time flood or drought monitoring or forecasting so far. The Horizon 2020 funded EGSIEM (European Gravity Service for Improved Emergency Management) project is scheduled to launch a near-real time test run of GRACE gravity field data, which will provide daily solutions with a latency of 5 days. This fast availability allows the monitoring of total water storage variations related to hydrological extreme events as they occur, as opposed to a 'confirmation after occurrence', which is the current situation. A first hydrological evaluation of daily GRACE gravity field solutions for floods in the Ganges-Brahmaputra Delta in 2004 and 2007 confirms their potential for gravity-based large-scale flood monitoring. This particularly applies to short-lived, high-volume floods, as they occur in Bangladesh with a 4-5 year return period. The subsequent assimilation of daily GRACE data into a (global) hydrological model - carried out jointly within the framework of the Belmont Forum funded BanD-AID project - decomposes total water storage into its individual components (e.g., surface water), increases the spatial resolution and opens up the possibility of flood early warning and forecasting.
The reliable solution and computation time of variable parameters logistic model
Wang, Pengfei; Pan, Xinnong
2017-04-01
The study investigates the reliable computation time (RCT, termed as T c) by applying a double-precision computation of a variable parameters logistic map (VPLM). Firstly, by using the proposed method, we obtain the reliable solutions for the logistic map. Secondly, we construct 10,000 samples of reliable experiments from a time-dependent non-stationary parameters VPLM and then calculate the mean T c. The results indicate that, for each different initial value, the T cs of the VPLM are generally different. However, the mean T c trends to a constant value when the sample number is large enough. The maximum, minimum, and probable distribution functions of T c are also obtained, which can help us to identify the robustness of applying a nonlinear time series theory to forecasting by using the VPLM output. In addition, the T c of the fixed parameter experiments of the logistic map is obtained, and the results suggest that this T c matches the theoretical formula-predicted value.
Real-time Numerical Solution for the Plasma Response Matrix for Disruption Avoidance in ITER
Glasser, Alexander; Kolemen, Egemen; Glasser, A. H.
2016-10-01
Real-time analysis of plasma stability is essential to any active feedback control system that performs ideal MHD disruption avoidance. Due to singularities and poor numerical conditioning endemic to ideal MHD models of tokamak plasmas, current state-of-the-art codes require serial operation, and are as yet inoperable on the sub- O (1s) timescale required by ITER's MHD evolution time. In this work, low-toroidal-n ideal MHD modes are found in near real-time as solutions to a well-posed boundary value problem. Using a modified parallel shooting technique and linear methods to subdue numerical instability, such modes are integrated with parallelization across spatial and ``temporal'' parts, via a Riccati approach. The resulting state transition matrix is shown to yield the desired plasma response matrix, which describes how magnetic perturbations may be employed to maintain plasma stability. Such an algorithm may be helpful in designing a control system to achieve ITER's high-performance operational objectives. Sponsored by US DOE under DE-SC0015878 and DE-FC02-04ER54698.
Time of travel of solutes in the Sabine River basin, Texas, August-November 1996
Raines, Timothy H.
1997-01-01
The U.S. Geological Survey (USGS), in cooperation with the Sabine River Authority, did a time-of-travel study in the Sabine River Basin during low flow from August to November 1996. The study was done to provide accurate estimates of the time-of-travel and dispersion characteristics for solutes during low flow in a 1.8-mile (mi) reach of Grace Creek, a 23.9-mi reach of the mainstem Sabine River, a 3.4-mi reach of Hawkins Creek, and a 1.9-mi reach of Rocky Creek. This report explains the approach and documents the results of the study. The results of the study will be used by the Texas Natural Resource Conservation Commission in a water-quality model to determine waste-load allocation in Segment 0505 of the Sabine River Basin. The time-of-travel and dispersion characteristics also provide useful information on the probable behavior of soluble contaminants that might be introduced into the streams measured in this study.
Protein structural dynamics in solution unveiled via 100-ps time-resolved x-ray scattering
Energy Technology Data Exchange (ETDEWEB)
Cho, Hyun Sun; Dashdorj, Naranbaatar; Schotte, Friedrich; Graber, Timothy; Henning, Robert; Anfinruda, Philip (NIH); (UC)
2010-04-21
We have developed a time-resolved x-ray scattering diffractometer capable of probing structural dynamics of proteins in solution with 100-ps time resolution. This diffractometer, developed on the ID14B BioCARS (Consortium for Advanced Radiation Sources) beamline at the Advanced Photon Source, records x-ray scattering snapshots over a broad range of q spanning 0.02-2.5 {angstrom}{sup -1}, thereby providing simultaneous coverage of the small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) regions. To demonstrate its capabilities, we have tracked structural changes in myoglobin as it undergoes a photolysis-induced transition from its carbon monoxy form (MbCO) to its deoxy form (Mb). Though the differences between the MbCO and Mb crystal structures are small (rmsd < 0.2 {angstrom}), time-resolved x-ray scattering differences recorded over 8 decades of time from 100 ps to 10 ms are rich in structure, illustrating the sensitivity of this technique. A strong, negative-going feature in the SAXS region appears promptly and corresponds to a sudden > 22 {angstrom}{sup 3} volume expansion of the protein. The ensuing conformational relaxation causes the protein to contract to a volume {approx}2 {angstrom}{sup 3} larger than MbCO within {approx}10 ns. On the timescale for CO escape from the primary docking site, another change in the SAXS/WAXS fingerprint appears, demonstrating sensitivity to the location of the dissociated CO. Global analysis of the SAXS/WAXS patterns recovered time-independent scattering fingerprints for four intermediate states of Mb. These SAXS/WAXS fingerprints provide stringent constraints for putative models of conformational states and structural transitions between them.
Reduction in the ionospheric error for a single-frequency GPS timing solution using tomography
Directory of Open Access Journals (Sweden)
Cathryn N. Mitchell
2009-06-01
Full Text Available
Times;">Abstract
Times;">Single-frequency Global Positioning System (GPS receivers do not accurately compensate for the ionospheric delay imposed upon a GPS signal. They rely upon models to compensate for the ionosphere. This delay compensation can be improved by measuring it directly with a dual-frequency receiver, or by monitoring the ionosphere using real-time maps. This investigation uses a 4D tomographic algorithm, Multi Instrument Data Analysis System (MIDAS, to correct for the ionospheric delay and compares the results to existing single and dualfrequency techniques. Maps of the ionospheric electron density, across Europe, are produced by using data collected from a fixed network of dual-frequency GPS receivers. Single-frequency pseudorange observations are corrected by using the maps to find the excess propagation delay on the GPS L1 signals. Days during the solar maximum year 2002 and the October 2003 storm have been chosen to display results when the ionospheric delays are large and variable. Results that improve upon the use of existing ionospheric models are achieved by applying MIDAS to fixed and mobile single-frequency GPS timing solutions. The approach offers the potential for corrections to be broadcast over a local region, or provided via the internet and allows timing accuracies to within 10 ns to be achieved.
Timing Solution and Single-pulse Properties for Eight Rotating Radio Transients
Cui, B.-Y.; Boyles, J.; McLaughlin, M. A.; Palliyaguru, N.
2017-05-01
Rotating radio transients (RRATs), loosely defined as objects that are discovered through only their single pulses, are sporadic pulsars that have a wide range of emission properties. For many of them, we must measure their periods and determine timing solutions relying on the timing of their individual pulses, while some of the less sporadic RRATs can be timed by using folding techniques as we do for other pulsars. Here, based on Parkes and Green Bank Telescope (GBT) observations, we introduce our results on eight RRATs including their timing-derived rotation parameters, positions, and dispersion measures (DMs), along with a comparison of the spin-down properties of RRATs and normal pulsars. Using data for 24 RRATs, we find that their period derivatives are generally larger than those of normal pulsars, independent of any intrinsic correlation with period, indicating that RRATs’ highly sporadic emission may be associated with intrinsically larger magnetic fields. We carry out Lomb-Scargle tests to search for periodicities in RRATs’ pulse detection times with long timescales. Periodicities are detected for all targets, with significant candidates of roughly 3.4 hr for PSR J1623-0841 and 0.7 hr for PSR J1839-0141. We also analyze their single-pulse amplitude distributions, finding that log-normal distributions provide the best fits, as is the case for most pulsars. However, several RRATs exhibit power-law tails, as seen for pulsars emitting giant pulses. This, along with consideration of the selection effects against the detection of weak pulses, imply that RRAT pulses generally represent the tail of a normal intensity distribution.
Directory of Open Access Journals (Sweden)
Yingwei Li
2013-01-01
Full Text Available The global exponential stability issues are considered for almost periodic solution of the neural networks with mixed time-varying delays and discontinuous neuron activations. Some sufficient conditions for the existence, uniqueness, and global exponential stability of almost periodic solution are achieved in terms of certain linear matrix inequalities (LMIs, by applying differential inclusions theory, matrix inequality analysis technique, and generalized Lyapunov functional approach. In addition, the existence and asymptotically almost periodic behavior of the solution of the neural networks are also investigated under the framework of the solution in the sense of Filippov. Two simulation examples are given to illustrate the validity of the theoretical results.
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
By different fixed point theorems in cones, sufficient conditions for the existence and multiple existence of positive solutions to a class of second-order multi-point boundary value problem for dynamic equation on time scales are obtained.
Exact solutions of the Bianchi types V and IX via time-dependent quasi-Maxwell equations
Yavari, Morteza
2014-02-01
The exact solutions of the Einstein field equations for the Bianchi types V and IX in presence of a perfect fluid via the time-dependent quasi-Maxwell (TQM) equations are investigated by using the threading formalism.
The classical limit of the time dependent Hartree-Fock equation. I. The Weyl symbol of the solution
Amour, Laurent; Nourrigat, Jean
2011-01-01
We study the time evolution of the Weyl symbol of a solution of the time dependent Hartree Fock equation, assuming that for t=0, it has a Weyl symbol which is integrable in the phase space, such as all its derivatives. We prove that the solution has the same property for all t, and we give an asymptotic expansion, in L1 sense, of this Weyl symbol.
Directory of Open Access Journals (Sweden)
Te-Wen Tu
2015-01-01
Full Text Available An analytical solution for the heat transfer in hollow cylinders with time-dependent boundary condition and time-dependent heat transfer coefficient at different surfaces is developed for the first time. The methodology is an extension of the shifting function method. By dividing the Biot function into a constant plus a function and introducing two specially chosen shifting functions, the system is transformed into a partial differential equation with homogenous boundary conditions only. The transformed system is thus solved by series expansion theorem. Limiting cases of the solution are studied and numerical results are compared with those in the literature. The convergence rate of the present solution is fast and the analytical solution is simple and accurate. Also, the influence of physical parameters on the temperature distribution of a hollow cylinder along the radial direction is investigated.
Zanardo, S.; Basu, N. B.; Rao, P. C.
2009-12-01
Catchment biogeochemical responses are the result of superposition of diverse dynamic components, which can be related to climate forcing, water flow, and biogeochemical reactions. The interactions among these components are highly non-linear and contribute to the generation of emergent patterns at multiple spatial and temporal scales. The aim of this work is to explore the following biogeochemical signatures arising from such interactions: (1) the relationship between contaminant loads (L) and discharge (Q) at the annual timescale, leading to an apparent chemostatic relationship (i.e., linear L-Q plots) for different contaminants and at different spatial scales; (2) spatial patterns in the slope and the scatter of the L-Q relationships; and (3) correlation between the intra-annual flow duration curves (FDC) and the load duration curves (LDC). Exploring this relationship necessitates the use of a parsimonious model, with few spatially uniform time constants, that can generate synthetic time series of load and flow at the outlet of river basins. The Mass Response Functions (MRF) approach (Rinaldo et al., 2006), lends itself suitable for the purpose since it relies on the assumption that the evolution of solute concentration in the water pulses depends only on the residence time, and not on its trajectory - thus space is replaced by time. The model simulates the episodic delivery of water and contaminant pulses from the hillslopes to the stream network in response to temporally random but spatially uniform effective rainfall patterns. The domain is described by an immobile source zone in which first order biogeochemical reactions (degradation rate constant ke) alter the solute mass, while multiple mobile rainfall pulses exchange mass with the source zone following linear kinetics (mass transfer rate constant α). The biogeochemical module of MRF, that was originally written to simulate non-reactive tracer and nitrate transport, was modified to include the more
Mädler, Thomas
2012-01-01
Perturbations of the linearized vacuum Einstein equations on a null cone in the Bondi-Sachs formulation of General Relativity can be derived from a single master function with spin weight two which is determined by a simple wave equation. Utilizing a standard spin representation of the tensors on a sphere and two different approaches to solve the master equation, we are able to determine two simple and explicitly time-dependent solutions. Both solutions, of which one is asymptotically flat, comply with the regularity conditions at the vertex of the null cone. For the asymptotically flat solution we calculate the corresponding linearized perturbations, describing all multipoles of spin-2 waves that propagate on a Minkowskian background space-time. We also analyze the asymptotic behavior of this solution at null infinity using a Penrose compactification, and calculate the Weyl scalar \\Psi_4. Because of its simplicity, the asymptotically flat solution presented here is ideally suited for testbed calculations in ...
Energy Technology Data Exchange (ETDEWEB)
Chen, Jun, E-mail: chenjun.sun@gmail.com; Liu, Yun-xian, E-mail: liuyx@cjlu.edu.cn
2014-09-05
We construct explicit multisoliton complex solutions for multicomponent Bose–Einstein condensate systems with time- and spatial-coordinate-dependent atomic potentials and interactions. The exact solutions are used to analyze the important solitary matter wave properties such as the profiles of temporal and spatial multimode beams as well as focusing effects. Results demonstrate that soliton complexes can be controlled nonlinearly during the interaction by modulating the external potentials and nonlinearities. - Highlights: • An algebraic approach is proposed for the dynamics of multicomponent BECs. • External potentials and nonlinearities are time and space-dependent. • Analytical solutions are constructed. • Multisoliton complexes are predicted.
Routing Flow-Shop with Buffers and Ready Times – Comparison of Selected Solution Algorithms
Directory of Open Access Journals (Sweden)
Józefczyk Jerzy
2014-12-01
Full Text Available This article extends the former results concerning the routing flow-shop problem to minimize the makespan on the case with buffers, non-zero ready times and different speeds of machines. The corresponding combinatorial optimization problem is formulated. The exact as well as four heuristic solution algorithms are presented. The branch and bound approach is applied for the former one. The heuristic algorithms employ known constructive idea proposed for the former version of the problem as well as the Tabu Search metaheuristics. Moreover, the improvement procedure is proposed to enhance the quality of both heuristic algorithms. The conducted simulation experiments allow evaluating all algorithms. Firstly, the heuristic algorithms are compared with the exact one for small instances of the problem in terms of the criterion and execution times. Then, for larger instances, the heuristic algorithms are mutually compared. The case study regarding the maintenance of software products, given in the final part of the paper, illustrates the possibility to apply the results for real-world manufacturing systems.
Real-time monitoring and manipulation of single bio-molecules in free solution
Energy Technology Data Exchange (ETDEWEB)
Li, Hung-Wing [Iowa State Univ., Ames, IA (United States)
2005-01-01
The observation and manipulation of single biomolecules allow their dynamic behaviors to be studied to provide insight into molecular genetics, biochip assembly, biosensor design, DNA biophysics. In a PDMS/glass microchannel, a nonuniform electroosmotic flow (EOF) was created. By using a scanning confocal fluorescence microscope and total internal-reflection fluorescence microscope (TIRFM), we demonstrated that negatively charged DNA molecules were focused by the nonuniform EOF into a thin layer at the glass surface. This phenomenon was applied to selectively detect target DNA molecules without requiring the separation of excessive probes and can be applied continuously to achieve high throughput. A variable-angle-TIRFM was constructed for imaging single DNA molecule dynamics at a solid/liquid interface. Implications we have are that the measured intensities cannot be used directly to determine the distances of molecules from the surface and the experimental counting results depict the distance-dependent dynamics of molecules near the surface; Molecules at low ionic strengths experience electrostatic repulsion at distances much further away from the surface than the calculated thickness of the electrical double layer. {delta}-DNA was employed as a nanoprobe for different functionalized surfaces to elucidate adsorption in chromatography. The 12-base unpaired ends of this DNA provide exposed purine and pyrimidine groups for adsorption. Patterns of self-assembled monolayers (SAMs) and patterns of metal oxides are generated. By recording the real-time dynamic motion of DNA molecules at the SAMs/aqueous interface, the various parameters governing the retention of an analyte during chromatographic separation can be studied. Even subtle differences among adsorptive forces can be revealed. Dynamic conformational changes of the prosthetic group, flavin adenine dinucleotide (FAD), in flavoprotein NADH peroxidase, in thioredoxin reductase, and in free solution were monitored
Cardona, A.; Montes, C.; Bayona, G.; Jaramillo, S.; Lopez-Martinez, M.; Silva, J.; Valencia, V.; Vanegas, J.; Zapata, S.
2013-05-01
Large scale plate tectonic scale models of the Caribbean-South American interactions have suggest the existence of different Late Cretaceous to Eocene collisional and subduction events associated to the Caribbean and South American plates interactions. We integrate field, petrological and geochronological results from igneous, metamorphic and sedimentary rocks from northeastern Colombia Guajira and Santa Margin in order to accurately discriminate the timing and understand with more details the processes associated to the evolution from collision to subduction and oblique convergence between the Caribbean and South America. Geochronological data from metamorphic units in the Santa Marta and Guajira regions document Late Cretaceous and Early Paleocene deformational events link to the collision of the Caribbean plate margin and the subsequent inversion of the upper plate during subduction initiation. Contemporaneous with these metamorphic events, inland basins experienced two major peaks of subsidence that can be related to the advance and overthrusting of the continental plate within the same tectonic scenario of collision and renewed subductions. This was followed by the construction of an Early Eocene magmatic arc located within the upper plate in a near trench position. Shallow and "fore arc" melting was related to the early astenospheric influx under the upper plate during the early stages of subduction. Another Late Eocene-Oligocene deformation is related to thrusting of the arc, exhumation and inland migration of deformation. This event may be related to major changes in the rates and directions of plate convergence between the Caribbean and South American plates.
Investigation of Noises in GPS Time Series: Case Study on Epn Weekly Solutions
Klos, Anna; Bogusz, Janusz; Figurski, Mariusz; Kosek, Wieslaw; Gruszczynski, Maciej
2014-05-01
The noises in GPS time series are stated to be described the best by the combination of white (Gaussian) and power-law processes. They are mainly the effect of mismodelled satellite orbits, Earth orientation parameters, atmospheric effects, antennae phase centre effects, or of monument instability. Due to the fact, that velocities of permanent stations define the kinematic reference frame, they have to fulfil the requirement of being stable at 0.1 mm/yr. The previously performed researches showed, that the wrong assumption of noise model leads to the underestimation of velocities and their uncertainties from 2 up to even 11, especially in the Up direction. This presentation focuses on more than 200 EPN (EUREF Permanent Network) stations from the area of Europe with various monument types (concrete pillars, buildings, metal masts, with or without domes, placed on the ground or on the rock) and coordinates of weekly changes (GPS weeks 0834-1459). The topocentric components (North, East, Up) in ITRF2005 which come from the EPN Re-Processing made by the Military University of Technology Local Analysis Centre (MUT LAC) were processed with Maximum Likelihood Estimation (MLE) using CATS software. We have assumed the existence of few combinations of noise models (these are: white, flicker and random walk noise with integer spectral indices and power-law noise models with fractional spectral indices) and investigated which of them EPN weekly time series are likely to follow. The results show, that noises in GPS time series are described the best by the combination of white and flicker noise model. It is strictly related to the so-called common mode error (CME) that is spatially correlated error being one of the dominant error source in GPS solutions. We have assumed CME as spatially uniform, what was a good approximation for stations located hundreds of kilometres one to another. Its removal with spatial filtering reduces the amplitudes of white and flicker noise by a
Manna, M A
1997-01-01
We study solitary-wave and kink-wave solutions of a modified Boussinesq equation through a multiple-time reductive perturbation method. We use appropriated modified Korteweg-de Vries hierarchies to eliminate secular producing terms in each order of the perturbative scheme. We show that the multiple-time variables needed to obtain a regular perturbative series are completely determined by the associated linear theory in the case of a solitary-wave solution, but requires the knowledge of each order of the perturbative series in the case of a kink-wave solution. These appropriate multiple-time variables allow us to show that the solitary-wave as well as the kink-wave solutions of the modified Botussinesq equation are actually respectively a solitary-wave and a kink-wave satisfying all the equations of suitable modified Korteweg-de Vries hierarchies.
Zhang, Xiaolong; Li, Liang; Pan, Deng; Cao, Chengmao; Song, Jian
2014-03-01
The current research of real-time observation for vehicle roll steer angle and compliance steer angle(both of them comprehensively referred as the additional steer angle in this paper) mainly employs the linear vehicle dynamic model, in which only the lateral acceleration of vehicle body is considered. The observation accuracy resorting to this method cannot meet the requirements of vehicle real-time stability control, especially under extreme driving conditions. The paper explores the solution resorting to experimental method. Firstly, a multi-body dynamic model of a passenger car is built based on the ADAMS/Car software, whose dynamic accuracy is verified by the same vehicle's roadway test data of steady static circular test. Based on this simulation platform, several influencing factors of additional steer angle under different driving conditions are quantitatively analyzed. Then ɛ-SVR algorithm is employed to build the additional steer angle prediction model, whose input vectors mainly include the sensor information of standard electronic stability control system(ESC). The method of typical slalom tests and FMVSS 126 tests are adopted to make simulation, train model and test model's generalization performance. The test result shows that the influence of lateral acceleration on additional steer angle is maximal (the magnitude up to 1°), followed by the longitudinal acceleration-deceleration and the road wave amplitude (the magnitude up to 0.3°). Moreover, both the prediction accuracy and the calculation real-time of the model can meet the control requirements of ESC. This research expands the accurate observation methods of the additional steer angle under extreme driving conditions.
Raslan, K. R.; EL-Danaf, Talaat S.; Ali, Khalid K.
2017-07-01
In the present paper, we established a traveling wave solution by using modified Kudryashov method for the space-time fractional nonlinear partial differential equations. The method is used to obtain the exact solutions for different types of the space-time fractional nonlinear partial differential equations such as, the space-time fractional coupled equal width wave equation (CEWE) and the space-time fractional coupled modified equal width wave equation (CMEW), which are the important soliton equations. Both equations are reduced to ordinary differential equations by the use of fractional complex transform and properties of modified Riemann-Liouville derivative. We plot the exact solutions for these equations at different time levels.
Rivals, Florent; Schulz, Ellen; Kaiser, Thomas M.
2009-12-01
Mesowear and microwear on enamel from 763 teeth of middle and late Pleistocene ungulates were analysed to infer the potential of dental wear analysis of faunal remains as a paleoenvironmental and paleoclimatic proxy in relation to climatic changes and diversity of vegetation available in the environment. Fossil localities including levels belonging to two glacial and two interglacial stages were selected in Germany, France, and Spain. At a temporal scale, results indicate that the dietary diversity in ungulates is higher during interglacial phases (MIS 5 and 3) than during pleniglacial phases (MIS 8 and 4). Dietary diversity is concluded to be related to climate-driven vegetation changes which during interglacials lead to increased variety of potential food items available to ungulates. At the geographical scale, during interglacials, changes in diet composition are evident along geographical gradients. The corresponding dietary gradients are proposed to be related to climate and vegetation gradients reflecting more arid climates in the Mediterranean area compared to North-Western Europe. Species consistently represented at all localities investigated are Cervus elaphus (Cervidae, Artiodactyla) and Equus ferus (Equidae, Perissodactyla). C. elaphus populations are found to consistently have less abrasive diets than E. ferus populations but dietary traits of both species varied largely, revealing a significant plasticity in the feeding adaptation of both species. Those traits are concluded to be related to differences in vegetation structure at each locality and complement the evidence that ungulates have broader dietary habits than what is usually assumed.
Patwardhan, Amol V.; Fuller, George M.
2014-09-01
We show that a particular class of postrecombination phase transitions in the vacuum can lead to localized overdense regions on relatively small scales, roughly 106 to 1010M⊙, potentially interesting for the origin of large black hole seeds and for dwarf galaxy evolution. Our study suggests that this mechanism could operate over a range of conditions which are consistent with current cosmological and laboratory bounds. One byproduct of phase transition bubble-wall decay may be extra radiation energy density. This could provide an avenue for constraint, but it could also help reconcile the discordant values of the present Hubble parameter (H0) and σ8 obtained by cosmic microwave background (CMB) fits and direct observational estimates. We also suggest ways in which future probes, including CMB considerations (e.g., early dark energy limits), 21-cm observations, and gravitational radiation limits, could provide more stringent constraints on this mechanism and the sub-eV scale beyond-standard-model physics, perhaps in the neutrino sector, on which it could be based. Late phase transitions associated with sterile neutrino mass and mixing may provide a way to reconcile cosmological limits and laboratory data, should a future disagreement arise.
Institute of Scientific and Technical Information of China (English)
P. J. Brantingham; MA Haizhou; J. W. Olsen; GAO Xing; D. B. Madsen; D. E. Rhode
2003-01-01
Hunter-gatherer populations in greater northeast Asia experienced dramatic range expansions during the early Upper Paleolithic (45-22 ka) and the late Upper Paleolithic (18-10 ka), both of which led to intensive occupations of cold desert environments including the Mongolian Gobi and northwest China. Range contractions under the cold, arid extremes of the Last Glacial Maximum (LGM, 22-18 ka) may have entailed widespread population extirpations. The high elevation Qinghai-Tibetan Plateau is significantly more extreme in both climate and environment than either the Gobi or the Siberian taiga forests, and provides an ideal setting to test fundamental models of human biogeog-raphy in the context of regional population fluctuations. The area is presently occupied primarily by nomadic pastoralists, but it is clear that these complex middle Holocene (<6 ka) economic adaptations were not a necessary prerequisite for successful colonization of the high elevation Plateau. Exploratory field-work in 2000-2001 has established that Upper Paleolithic hunter-gatherers were present on the Qinghai-Tibetan Plateau by at least 12 ka and possibly much earlier. Aspeculative model for the colonization process is developed and preliminary archaeological data in support of the model are presented.
The Eclipse of the Sun: Sun-dials, Clocks and Natural Time in the Late Seventeenth Century.
Turner, Anthony
2015-01-01
The Sun, in the early seventeenth century was, as it always had been, the ultimate arbiter of time-measurement In the last quarter of the century however this role was called into question as the new precision of post-Huygenian clocks revealed that natural time and the artificial mean time of the clock were not the same. Initially the question was little understood by the general public. The paper examines some early attempts to explain why "Sun-time" in 1700 was no longer "true-time."
Time-dependent rotating stratified shear flow: exact solution and stability analysis.
Salhi, A; Cambon, C
2007-01-01
A solution of the Euler equations with Boussinesq approximation is derived by considering unbounded flows subjected to spatially uniform density stratification and shear rate that are time dependent [S(t)= partial differentialU3/partial differentialx2]. In addition to vertical stratification with constant strength N(v)2, this base flow includes an additional, horizontal, density gradient characterized by N(h)2(t). The stability of this flow is then analyzed: When the vertical stratification is stabilizing, there is a simple harmonic motion of the horizontal stratification N(h)2(t) and of the shear rate S(t), but this flow is unstable to certain disturbances, which are amplified by a Floquet mechanism. This analysis may involve an additional Coriolis effect with Coriolis parameter f, so that governing dimensionless parameters are a modified Richardson number, R=[S(0)2+N(h)4(0)/N(v)2]1/2, and f(v)=f/N(v), as well as the initial phase of the periodic shear rate. Parametric resonance between the inertia-gravity waves and the oscillating shear is demonstrated from the dispersion relation in the limit R-->0. The parametric instability has connection with both baroclinic and elliptical flow instabilities, but can develop from a very different base flow.
Discrete-time nonlinear HJB solution using approximate dynamic programming: convergence proof.
Al-Tamimi, Asma; Lewis, Frank L; Abu-Khalaf, Murad
2008-08-01
Convergence of the value-iteration-based heuristic dynamic programming (HDP) algorithm is proven in the case of general nonlinear systems. That is, it is shown that HDP converges to the optimal control and the optimal value function that solves the Hamilton-Jacobi-Bellman equation appearing in infinite-horizon discrete-time (DT) nonlinear optimal control. It is assumed that, at each iteration, the value and action update equations can be exactly solved. The following two standard neural networks (NN) are used: a critic NN is used to approximate the value function, whereas an action network is used to approximate the optimal control policy. It is stressed that this approach allows the implementation of HDP without knowing the internal dynamics of the system. The exact solution assumption holds for some classes of nonlinear systems and, specifically, in the specific case of the DT linear quadratic regulator (LQR), where the action is linear and the value quadratic in the states and NNs have zero approximation error. It is stressed that, for the LQR, HDP may be implemented without knowing the system A matrix by using two NNs. This fact is not generally appreciated in the folklore of HDP for the DT LQR, where only one critic NN is generally used.