Surgical timing of the orbital "blowout" fracture
DEFF Research Database (Denmark)
Damgaard, Olaf Ehlers; Larsen, Christian Grønhøj; Felding, Ulrik Ascanius
2016-01-01
Objective: The orbital blowout fracture is a common facial injury, carrying with it a risk of visual impairment and undesirable cosmetic results unless treated properly. Optimal timing of the surgical treatment is still a matter of debate. We set out to determine whether a meta-analysis would bring...
Modeling and prediction of surgical procedure times
P.S. Stepaniak (Pieter); C. Heij (Christiaan); G. de Vries (Guus)
2009-01-01
textabstractAccurate prediction of medical operation times is of crucial importance for cost efficient operation room planning in hospitals. This paper investigates the possible dependence of procedure times on surgeon factors like age, experience, gender, and team composition. The effect of these f
Irregular Time Dependent Obstacles
Lindqvist, Peter
2010-01-01
We study the obstacle problem for the Evolutionary p-Laplace Equation when the obstacle is discontinuous and without regularity in the time variable. Two quite different procedures yield the same solution.
Peripheral surgical wounding and age-dependent neuroinflammation in mice.
Directory of Open Access Journals (Sweden)
Zhipeng Xu
Full Text Available Post-operative cognitive dysfunction is associated with morbidity and mortality. However, its neuropathogenesis remains largely to be determined. Neuroinflammation and accumulation of β-amyloid (Aβ have been reported to contribute to cognitive dysfunction in humans and cognitive impairment in animals. Our recent studies have established a pre-clinical model in mice, and have found that the peripheral surgical wounding without the influence of general anesthesia induces an age-dependent Aβ accumulation and cognitive impairment in mice. We therefore set out to assess the effects of peripheral surgical wounding, in the absence of general anesthesia, on neuroinflammation in mice with different ages. Abdominal surgery under local anesthesia was established in 9 and 18 month-old mice. The levels of tumor necrosis factor-α (TNF-α, interleukin-6 (IL-6, Iba1 positive cells (the marker of microglia activation, CD33, and cognitive function in mice were determined. The peripheral surgical wounding increased the levels of TNF-α, IL-6, and Iba1 positive cells in the hippocampus of both 9 and 18 month-old mice, and age potentiated these effects. The peripheral surgical wounding increased the levels of CD33 in the hippocampus of 18, but not 9, month-old mice. Finally, anti-inflammatory drug ibuprofen ameliorated the peripheral surgical wounding-induced cognitive impairment in 18 month-old mice. These data suggested that the peripheral surgical wounding could induce an age-dependent neuroinflammation and elevation of CD33 levels in the hippocampus of mice, which could lead to cognitive impairment in aged mice. Pending further studies, anti-inflammatory therapies may reduce the risk of postoperative cognitive dysfunction in elderly patients.
Ioannidou, Theodora
2016-01-01
An extended version of the BPS Skyrme model that admits time-dependent solutions is discussed. Initially, by introducing a power law at the original potential term of the BPS Skyrme model the existence, stability and structure of the corresponding solutions is investigated. Then, the frequencies and half-lifes of the radial oscillations of the constructed time-dependent solutions are determined.
Time-Dependent Lagrangian Biomechanics
Ivancevic, Tijana T
2009-01-01
In this paper we present the time-dependent generalization of an 'ordinary' autonomous human musculo-skeletal biomechanics. We start with the configuration manifold of human body, given as a set of its all active degrees of freedom (DOF). This is a Riemannian manifold with a material metric tensor given by the total mass-inertia matrix of the human body segments. This is the base manifold for standard autonomous biomechanics. To make its time-dependent generalization, we need to extend it with a real time axis. On this extended configuration space we develop time-dependent biomechanical Lagrangian dynamics, using derived jet spaces of velocities and accelerations, as well as the underlying geometric evolution of the mass-inertia matrix. Keywords: Human time-dependent biomechanics, configuration manifold, jet spaces, geometric evolution
On time dependent Ekman transports
National Research Council Canada - National Science Library
Roed, L.P
1973-01-01
One of the most cited papers in ocean current theories is the paper by Ekman (1905). Here we take his paper as a starting point for computing time dependent solutions for the integrated velocities or the transports.
Models for dependent time series
Tunnicliffe Wilson, Granville; Haywood, John
2015-01-01
Models for Dependent Time Series addresses the issues that arise and the methodology that can be applied when the dependence between time series is described and modeled. Whether you work in the economic, physical, or life sciences, the book shows you how to draw meaningful, applicable, and statistically valid conclusions from multivariate (or vector) time series data.The first four chapters discuss the two main pillars of the subject that have been developed over the last 60 years: vector autoregressive modeling and multivariate spectral analysis. These chapters provide the foundational mater
Time-Dependent Lagrangian Biomechanics
Ivancevic, Tijana T.
2009-01-01
In this paper we present the time-dependent generalization of an 'ordinary' autonomous human musculo-skeletal biomechanics. We start with the configuration manifold of human body, given as a set of its all active degrees of freedom (DOF). This is a Riemannian manifold with a material metric tensor given by the total mass-inertia matrix of the human body segments. This is the base manifold for standard autonomous biomechanics. To make its time-dependent generalization, we need to extend it wit...
Leraas, Harold J; Cox, Morgan L; Bendersky, Victoria A; Sprinkle, Shanna S; Gilmore, Brian F; Gunasingha, Rathnayaka M; Tracy, Elisabeth T; Sudan, Ranjan
2017-10-04
Surgical skills training varies greatly between institutions and is often left to students to approach independently. Although many studies have examined single interventions of skills training, no data currently exists about the implementation of surgical skills assessment as a component of the medical student surgical curriculum. We created a technical skills competition and evaluated its effect on student surgical skill development. Second-year medical students enrolled in the surgery clerkship voluntarily participated in a surgical skills competition consisting of knot tying, laparoscopic peg transfer, and laparoscopic pattern cut. Winning students were awarded dinner with the chair of surgery and a resident of their choice. Individual event times and combined times were recorded and compared for students who completed without disqualification. Disqualification included compromising cutting pattern, dropping a peg out of the field of vision, and incorrect knot tying technique. Timed performance was compared for 2 subsequent academic years using Mann-Whitney U test. Overall, 175 students competed and 71 students met qualification criteria. When compared by academic year, 2015 to 2016 students (n = 34) performed better than 2014 to 2015 students (n = 37) in pattern cut (133s vs 167s, p = 0.040), peg transfer (66s vs 101s, p skills competition improves student technical performance. Further research is needed regarding long-term benefits of surgical competitions for medical students. Copyright © 2017 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.
LENUS (Irish Health Repository)
Kelly, B D
2012-01-31
BACKGROUND: On the 1 August 2009, the implementation of European Working Time Directive became European law and was implemented in Galway University Hospital (GUH). AIMS: The aim of the study is to ascertain the opinion of the 25 surgical SHOs in GUH on the effect of the implementation of an EWTD compliant roster had on the quality of their training. METHODS: A questionnaire was circulated to all 25 surgical SHOs. RESULTS: Twenty-two (88%) SHOs report a reduction in the quality of their training. 18 (72%) report a reduction in the development of their operative skills. The SHOs believed the EWTD Rotas would encourage Irish graduates to train abroad. CONCLUSIONS: Surgical training faces a challenge with the implementation of EWTD Rotas. Major changes need to be made to the surgical training structure to train surgeons to the highest standard and to retain Irish-trained surgeons in the Irish healthcare system.
[Surgical indication and timing in infective endocarditis].
Di Eusanio, Marco; Murana, Giacomo; Viale, Pierluigi; Rapezzi, Claudio; Di Bartolomeo, Roberto
2014-12-01
Infective endocarditis is a complex disease to treat. Despite considerable improvements in diagnostic and therapeutic management, mortality in infective endocarditis remains high. Recent data converge in giving a central role to surgery that, within a multidisciplinary approach and with earlier timing, primarily aims to eradicate the infection rather than to treat its acute or chronic complications. In this paper, we sought to review and comment on current available data and last recommendations for the management of patients with infective endocarditis.
Time dependence of immersion freezing
Directory of Open Access Journals (Sweden)
A. Welti
2012-05-01
Full Text Available The time dependence of immersion freezing was studied for temperatures between 236 K and 243 K. Droplets with single immersed, size-selected 400 nm and 800 nm kaolinite particles were produced at 300 K, cooled down to supercooled temperatures typical for mixed-phase cloud conditions, and the fraction of frozen droplets with increasing residence time was detected. To simulate the conditions of immersion freezing in mixed-phase clouds we used the Zurich Ice Nucleation Chamber (ZINC and its vertical extension, the Immersion Mode Cooling chAmber (IMCA. We observed that the frozen fraction of droplets increased with increasing residence time in the chamber. This suggests that there is a time dependence of immersion freezing and supports the importance of a stochastic component in the ice nucleation process. The rate at which droplets freeze was observed to decrease towards higher temperatures and smaller particle sizes. Comparison of the laboratory data with four different ice nucleation models, three based on classical nucleation theory with different representations of the particle surface properties and one singular, suggest that the classical, stochastic approach combined with a distribution of contact angles is able to reproduce the ice nucleation observed in these experiments most accurately. Using the models to calculate the increase in frozen fraction at typical mixed-phase cloud temperatures over an extended period of time, yields an equivalent effect of −1 K temperature shift and an increase in time scale by a factor of ~10.
Network-timing-dependent plasticity
Directory of Open Access Journals (Sweden)
Vincent eDelattre
2015-06-01
Full Text Available Bursts of activity in networks of neurons are thought to convey salient information and drive synaptic plasticity. Here we report that network bursts also exert a profound effect on Spike-Timing-Dependent Plasticity (STDP. In acute slices of juvenile rat somatosensory cortex we paired a network burst, which alone induced long-term depression (LTD, with STDP-induced long-term potentiation and depression (LTP and LTD. We observed that STDP-induced LTP was either unaffected, blocked or flipped into LTD by the network burst, and that STDP-induced LTD was either saturated or flipped into LTP, depending on the relative timing of the network burst with respect to spike coincidences of the STDP event. We hypothesized that network bursts flip STDP-induced LTP to LTD by depleting resources needed for LTP and therefore developed a resource-dependent STDP learning rule. In a model neural network under the influence of the proposed resource-dependent STDP rule, we found that excitatory synaptic coupling was homeostatically regulated to produce power law distributed burst amplitudes reflecting self-organized criticality, a state that ensures optimal information coding.
Network-timing-dependent plasticity.
Delattre, Vincent; Keller, Daniel; Perich, Matthew; Markram, Henry; Muller, Eilif B
2015-01-01
Bursts of activity in networks of neurons are thought to convey salient information and drive synaptic plasticity. Here we report that network bursts also exert a profound effect on Spike-Timing-Dependent Plasticity (STDP). In acute slices of juvenile rat somatosensory cortex we paired a network burst, which alone induced long-term depression (LTD), with STDP-induced long-term potentiation (LTP) and LTD. We observed that STDP-induced LTP was either unaffected, blocked or flipped into LTD by the network burst, and that STDP-induced LTD was either saturated or flipped into LTP, depending on the relative timing of the network burst with respect to spike coincidences of the STDP event. We hypothesized that network bursts flip STDP-induced LTP to LTD by depleting resources needed for LTP and therefore developed a resource-dependent STDP learning rule. In a model neural network under the influence of the proposed resource-dependent STDP rule, we found that excitatory synaptic coupling was homeostatically regulated to produce power law distributed burst amplitudes reflecting self-organized criticality, a state that ensures optimal information coding.
Time-Dependent Seismic Tomography
Julian, B. R.
2008-12-01
Temporal changes in seismic wave speeds in the Earth's crust have been measured at several locations, notably The Geysers geothermal area in California, in studies that used three-dimensional seismic tomography. These studies have used conventional tomography methods to invert multiple seismic-wave arrival time data sets independently and assumed that any differences in the derived structures reflect real temporal variations. Such an assumption is dangerous because the results of repeated tomography experiments would differ even if the structure did not change, simply because of variation in the seismic ray distribution caused by the natural variation in earthquake locations. This problem can be severe when changes in the seismicity distribution are systematic, as, for example, at the onset of an aftershock sequence. The sudden change in the ray distribution can produce artifacts that mimic changes in the seismic wave speeds at the time of a large earthquake. Even if the source locations did not change (if only explosion data were used, for example), derived structures would inevitably differ because of observational errors. A better approach to determining what temporal changes are truly required by the data is to invert multiple data sets simultaneously, imposing constraints to minimize differences between the models for different epochs. This problem is similar to that of seeking models similar to some a priori initial assumption, and a method similar to "damped least squares" can solve it. The order of the system of normal equations for inverting data from two epochs is twice as large as that for a single epoch, and solving it by standard methods requires eight times the computational labor. We present an algorithm for reducing this factor to two, so that inverting multiple epochs simultaneously is comparable in difficulty to inverting them independently, and illustrate its performance using synthetic arrival times and observed data from several areas in
Holographic Complexity for Time-Dependent Backgrounds
Momeni, Davood; Bahamonde, Sebastian; Myrzakulov, Ratbay
2016-01-01
In this paper, we will analyse the holographic complexity for time-dependent asymptotically $AdS$ geometries. We will first use a covariant zero mean curvature slicing of the time-dependent bulk geometries, and then use this co-dimension one spacelike slice of the bulk spacetime to define a co-dimension two minimal surface. The time-dependent holographic complexity will be defined using the volume enclosed by this minimal surface. This time-dependent holographic complexity will reduce to the usual holographic complexity for static geometries. We will analyse the time-dependence as a perturbation of the asymptotically $AdS$ geometries. Thus, we will obtain time-dependent asymptotically $AdS$ geometries, and we will calculate the holographic complexity for such a time-dependent geometries.
Time-dependent seismic tomography
Julian, B.R.; Foulger, G.R.
2010-01-01
Of methods for measuring temporal changes in seismic-wave speeds in the Earth, seismic tomography is among those that offer the highest spatial resolution. 3-D tomographic methods are commonly applied in this context by inverting seismic wave arrival time data sets from different epochs independently and assuming that differences in the derived structures represent real temporal variations. This assumption is dangerous because the results of independent inversions would differ even if the structure in the Earth did not change, due to observational errors and differences in the seismic ray distributions. The latter effect may be especially severe when data sets include earthquake swarms or aftershock sequences, and may produce the appearance of correlation between structural changes and seismicity when the wave speeds are actually temporally invariant. A better approach, which makes it possible to assess what changes are truly required by the data, is to invert multiple data sets simultaneously, minimizing the difference between models for different epochs as well as the rms arrival-time residuals. This problem leads, in the case of two epochs, to a system of normal equations whose order is twice as great as for a single epoch. The direct solution of this system would require twice as much memory and four times as much computational effort as would independent inversions. We present an algorithm, tomo4d, that takes advantage of the structure and sparseness of the system to obtain the solution with essentially no more effort than independent inversions require. No claim to original US government works Journal compilation ?? 2010 RAS.
Inspiration from Victorian times in Ultrasonic Surgical Tool Design
Ganilova, O. A.; Lucas, M.; Pan, Z.; Y Muir, A.; Simpson, H.
2012-08-01
This work is devoted to the investigation of performance of surgical tools used in orthopaedics in terms of the occurrence of signs of necrosis, the accuracy of the cut and cutting tool design. For the comparison of the surgical tool performance different types of cutting devices were studied in a series of experiments. A Victorian surgical saw, its copy, a contemporary surgical saw, a surgical scalpel and an ultrasonic blade designed for a surgical application were chosen for the performance assessment. Such geometrical parameters as cutting edge shape, angle of teeth inclination, and sharpness of the cutting tools were analysed in terms of the quality of the cut and signs of necrosis. As a result of the analysis of experimental data obtained and theoretical insight the authors have come up with a creative solution for a novel design for a surgical ultrasonic blade which benefits from the design advantages of each of the analysed surgical tools and eliminates their drawbacks.
Competing risks and time-dependent covariates
DEFF Research Database (Denmark)
Cortese, Giuliana; Andersen, Per K
2010-01-01
Time-dependent covariates are frequently encountered in regression analysis for event history data and competing risks. They are often essential predictors, which cannot be substituted by time-fixed covariates. This study briefly recalls the different types of time-dependent covariates...
Real-time automatic registration in optical surgical navigation
Lin, Qinyong; Yang, Rongqian; Cai, Ken; Si, Xuan; Chen, Xiuwen; Wu, Xiaoming
2016-05-01
An image-guided surgical navigation system requires the improvement of the patient-to-image registration time to enhance the convenience of the registration procedure. A critical step in achieving this aim is performing a fully automatic patient-to-image registration. This study reports on a design of custom fiducial markers and the performance of a real-time automatic patient-to-image registration method using these markers on the basis of an optical tracking system for rigid anatomy. The custom fiducial markers are designed to be automatically localized in both patient and image spaces. An automatic localization method is performed by registering a point cloud sampled from the three dimensional (3D) pedestal model surface of a fiducial marker to each pedestal of fiducial markers searched in image space. A head phantom is constructed to estimate the performance of the real-time automatic registration method under four fiducial configurations. The head phantom experimental results demonstrate that the real-time automatic registration method is more convenient, rapid, and accurate than the manual method. The time required for each registration is approximately 0.1 s. The automatic localization method precisely localizes the fiducial markers in image space. The averaged target registration error for the four configurations is approximately 0.7 mm. The automatic registration performance is independent of the positions relative to the tracking system and the movement of the patient during the operation.
Real time process algebra with time-dependent conditions
Baeten, J.C.M.; Middelburg, C.A.
2000-01-01
We extend the main real time version of ACP presented in [6] with conditionals in which the condition depends on time. This extension facilitates flexible dependence of proccess behaviour on initialization time. We show that the conditions concerned generalize the conditions introduced earlier in a
Real time process algebra with time-dependent conditions
Baeten, J.C.M.; Middelburg, C.A.
2008-01-01
We extend the main real time version of ACP presented in [6] with conditionals in which the condition depends on time. This extension facilitates flexible dependence of proccess behaviour on initialization time. We show that the conditions concerned generalize the conditions introduced earlier in a
Real time process algebra with time-dependent conditions
Baeten, J.C.M.; Middelburg, C.A.
We extend the main real time version of ACP presented in [6] with conditionals in which the condition depends on time. This extension facilitates flexible dependence of proccess behaviour on initialization time. We show that the conditions concerned generalize the conditions introduced earlier
Bohr Hamiltonian with time-dependent potential
Naderi, L.; Hassanabadi, H.; Sobhani, H.
2016-04-01
In this paper, Bohr Hamiltonian has been studied with the time-dependent potential. Using the Lewis-Riesenfeld dynamical invariant method appropriate dynamical invariant for this Hamiltonian has been constructed and the exact time-dependent wave functions of such a system have been derived due to this dynamical invariant.
Anchieta, M V M; Salles, F A; Cassaro, B D; Quaresma, M M; Santos, B F O
2016-10-01
Presentation of a new cranioplasty technique employing a combination of two technologies: rapid prototyping and surgical navigation. This technique allows the reconstruction of the skull cap after the resection of a bone tumor in a single surgical time. The neurosurgeon plans the craniotomy previously on the EximiusMed software, compatible with the Eximius Surgical Navigator, both from the company Artis Tecnologia (Brazil). The navigator imports the planning and guides the surgeon during the craniotomy. The simulation of the bone fault allows the virtual reconstruction of the skull cap and the production of a personalized modelling mold using the Magics-Materialise (Belgium)-software. The mold and a replica of the bone fault are made by rapid prototyping by the company Artis Tecnologia (Brazil) and shipped under sterile conditions to the surgical center. The PMMA prosthesis is produced during the surgical act with the help of a hand press. The total time necessary for the planning and production of the modelling mold is four days. The precision of the mold is submillimetric and accurately reproduces the virtual reconstruction of the prosthesis. The production of the prosthesis during surgery takes until twenty minutes depending on the type of PMMA used. The modelling mold avoids contraction and dissipates the heat generated by the material's exothermic reaction in the polymerization phase. The craniectomy is performed with precision over the drawing made with the help of the Eximius Surgical Navigator, according to the planned measurements. The replica of the bone fault serves to evaluate the adaptation of the prosthesis as a support for the perforations and the placement of screws and fixation plates, as per the surgeon's discretion. This technique allows the adequate oncologic treatment associated with a satisfactory aesthetic result, with precision, in a single surgical time, reducing time and costs.
Machine scheduling with resource dependent processing times
Grigoriev, A.; Sviridenko, M.; Uetz, Marc Jochen
We consider machine scheduling on unrelated parallel machines with the objective to minimize the schedule makespan. We assume that, in addition to its machine dependence, the processing time of any job is dependent on the usage of a discrete renewable resource, e.g. workers. A given amount of that
Time-Dependent Transport in Nanoscale Devices
Institute of Scientific and Technical Information of China (English)
CHEN Zhi-Dong; ZHANG Jin-Yu; YU Zhi-Ping
2009-01-01
A method for simulating ballistic time-dependent device transport,which solves the time-dependent SchrSdinger equation using the finite difference time domain (FDTD) method together with Poisson's equation,is described in detail The effective mass SchrSdinger equation is solved. The continuous energy spectrum of the system is discretized using adaptive mesh,resulting in energy levels that sample the density-of-states.By calculating time evolution of wavefunctions at sampled energies,time-dependent transport characteristics such as current and charge density distributions are obtained.Simulation results in a uanowire and a coaxially gated carbon nanotube field-effect transistor (CNTFET) are presented.Transient effects,e.g.,finite rising time,are investigated in these devices.
ALCHEMIC: Advanced time-dependent chemical kinetics
Semenov, Dmitry A.
2017-08-01
ALCHEMIC solves chemical kinetics problems, including gas-grain interactions, surface reactions, deuterium fractionization, and transport phenomena and can model the time-dependent chemical evolution of molecular clouds, hot cores, corinos, and protoplanetary disks.
Coasting cosmologies with time dependent cosmological constant
Pimentel, L O; Pimentel, Luis O.
1999-01-01
The effect of a time dependent cosmological constant is considered in a family of scalar tensor theories. Friedmann-Robertson-Walker cosmological models for vacumm and perfect fluid matter are found. They have a linear expansion factor, the so called coasting cosmology, the gravitational "constant" decreace inversely with time; this model satisfy the Dirac hipotesis. The cosmological "constant" decreace inversely with the square of time, therefore we can have a very small value for it at present time.
Surgical site infection prevention: time to move beyond the surgical care improvement program.
Hawn, Mary T; Vick, Catherine C; Richman, Joshua; Holman, William; Deierhoi, Rhiannon J; Graham, Laura A; Henderson, William G; Itani, Kamal M F
2011-09-01
The objective of this study was to evaluate whether the Surgical Care Improvement Project (SCIP) improved surgical site infection (SSI) rates using national data at the patient level for both SCIP adherence and SSI occurrence. The SCIP was established in 2006 with the goal of reducing surgical complications by 25% in 2010. National Veterans' Affairs (VA) data from 2005 to 2009 on adherence to 5 SCIP SSI prevention measures were linked to Veterans' Affairs Surgical Quality Improvement Program SSI outcome data. Effect of SCIP adherence and year of surgery on SSI outcome were assessed with logistic regression using generalized estimating equations, adjusting for procedure type and variables known to predict SSI. Correlation between hospital SCIP adherence and SSI rate was assessed using linear regression. There were 60,853 surgeries at 112 VA hospitals analyzed. SCIP adherence ranged from 75% for normothermia to 99% for hair removal and all significantly improved over the study period (P Surgical site infection occurred after 6.2% of surgeries (1.6% for orthopedic surgeries to 11.3% for colorectal surgeries). None of the 5 SCIP measures were significantly associated with lower odds of SSI after adjusting for variables known to predict SSI and procedure type. Year was not associated with SSI (P = 0.71). Hospital SCIP performance was not correlated with hospital SSI rates (r = -0.06, P = 0.54). Adherence to SCIP measures improved whereas risk-adjusted SSI rates remained stable. SCIP adherence was neither associated with a lower SSI rate at the patient level, nor associated with hospital SSI rates. Policies regarding continued SCIP measurement and reporting should be reassessed.
Pulsar braking: Time dependent moment of inertia?
Urbanec, Martin
2017-08-01
Pulsars rotate with extremely stable rotational frequency enabling one to measure its first and second time derivatives. These observed values can be combined to the so-called braking index. However observed values of braking index differ from the theoretical value of 3 corresponding to braking by magnetic dipole radiation being the dominant theoretical model. Such a difference can be explained by contribution of other mechanism like pulsar wind or quadrupole radiation, or by time dependency of magnetic field or moment of inertia. In this presentation we focus on influence of time dependent moment of inertia on the braking index. We will also discuss possible physical models for time-dependence of moment of inertia.
Time-Dependent Effect of Chlorhexidine Surgical Prep
2011-10-15
skin prep prior to venous puncture for blood cultures has resulted in a lower false-positive ratewhen compared to non-alcoholic povidoneeiodine.9...vascular catheter-site care: a meta-analysis. Ann Intern Med 2002;136:792e801. 9. Caldeira D, David C, Sampaio C. Skin antiseptics in venous puncture -site...load throughout the entire duration of the study. Regarding skin preparation prior to insertion of central venous pressure catheters, the current
Time-dependent species sensitivity distributions.
Fox, David R; Billoir, Elise
2013-02-01
Time is a central component of toxicity assessments. However, current ecotoxicological practice marginalizes time in concentration-response (C-R) modeling and species sensitivity distribution (SSD) analyses. For C-R models, time is invariably fixed, and toxicity measures are estimated from a function fitted to the data at that time. The estimated toxicity measures are used as inputs to the SSD modeling phase, which similarly avoids explicit recognition of the temporal component. The present study extends some commonly employed probability models for SSDs to derive theoretical results that characterize the time-dependent nature of hazardous concentration (HCx) values. The authors' results show that even from very simple assumptions, more complex patterns in the SSD time dependency can be revealed.
Investigations of Low Temperature Time Dependent Cracking
Energy Technology Data Exchange (ETDEWEB)
Van der Sluys, W A; Robitz, E S; Young, B A; Bloom, J
2002-09-30
The objective of this project was to investigate metallurgical and mechanical phenomena associated with time dependent cracking of cold bent carbon steel piping at temperatures between 327 C and 360 C. Boiler piping failures have demonstrated that understanding the fundamental metallurgical and mechanical parameters controlling these failures is insufficient to eliminate it from the field. The results of the project consisted of the development of a testing methodology to reproduce low temperature time dependent cracking in laboratory specimens. This methodology was used to evaluate the cracking resistance of candidate heats in order to identify the factors that enhance cracking sensitivity. The resultant data was integrated into current available life prediction tools.
Differential Geometry of Time-Dependent Mechanics
Giachetta, G; Sardanashvily, G
1997-01-01
The usual formulations of time-dependent mechanics start from a given splitting $Y=R\\times M$ of the coordinate bundle $Y\\to R$. From physical viewpoint, this splitting means that a reference frame has been chosen. Obviously, such a splitting is broken under reference frame transformations and time-dependent canonical transformations. Our goal is to formulate time-dependent mechanics in gauge-invariant form, i.e., independently of any reference frame. The main ingredient in this formulation is a connection on the bundle $Y\\to R$ which describes an arbitrary reference frame. We emphasize the following peculiarities of this approach to time-dependent mechanics. A phase space does not admit any canonical contact or presymplectic structure which would be preserved under reference frame transformations, whereas the canonical Poisson structure is degenerate. A Hamiltonian fails to be a function on a phase space. In particular, it can not participate in a Poisson bracket so that the evolution equation is not reduced...
Queues with waiting time dependent service
DEFF Research Database (Denmark)
Bekker, R.; Koole, G. M.; Nielsen, Bo Friis
2011-01-01
Motivated by service levels in terms of the waiting-time distribution seen, for instance, in call centers, we consider two models for systems with a service discipline that depends on the waiting time. The first model deals with a single server that continuously adapts its service rate based...... on the waiting time of the first customer in line. In the second model, one queue is served by a primary server which is supplemented by a secondary server when the waiting of the first customer in line exceeds a threshold. Using level crossings for the waiting-time process of the first customer in line, we...
An application-dependent framework for the recognition of high-level surgical tasks in the OR.
Lalys, Florent; Riffaud, Laurent; Bouget, David; Jannin, Pierre
2011-01-01
Surgical process analysis and modeling is a recent and important topic aiming at introducing a new generation of computer-assisted surgical systems. Among all of the techniques already in use for extracting data from the Operating Room, the use of image videos allows automating the surgeons' assistance without altering the surgical routine. We proposed in this paper an application-dependent framework able to automatically extract the phases of the surgery only by using microscope videos as input data and that can be adaptable to different surgical specialties. First, four distinct types of classifiers based on image processing were implemented to extract visual cues from video frames. Each of these classifiers was related to one kind of visual cue: visual cues recognizable through color were detected with a color histogram approach, for shape-oriented visual cues we trained a Haar classifier, for texture-oriented visual cues we used a bag-of-word approach with SIFT descriptors, and for all other visual cues we used a classical image classification approach including a feature extraction, selection, and a supervised classification. The extraction of this semantic vector for each video frame then permitted to classify time series using either Hidden Markov Model or Dynamic Time Warping algorithms. The framework was validated on cataract surgeries, obtaining accuracies of 95%.
Azzi, Alain Joe; Shah, Karan; Seely, Andrew; Villeneuve, James Patrick; Sundaresan, Sudhir R; Shamji, Farid M; Maziak, Donna E; Gilbert, Sebastien
2016-05-01
Health care resources are costly and should be used judiciously and efficiently. Predicting the duration of surgical procedures is key to optimizing operating room resources. Our objective was to identify factors influencing operative time, particularly surgical team turnover. We performed a single-institution, retrospective review of lobectomy operations. Univariate and multivariate analyses were performed to evaluate the impact of different factors on surgical time (skin-to-skin) and total procedure time. Staff turnover within the nursing component of the surgical team was defined as the number of instances any nurse had to leave the operating room over the total number of nurses involved in the operation. A total of 235 lobectomies were performed by 5 surgeons, most commonly for lung cancer (95%). On multivariate analysis, percent forced expiratory volume in 1 second, surgical approach, and lesion size had a significant effect on surgical time. Nursing turnover was associated with a significant increase in surgical time (53.7 minutes; 95% confidence interval, 6.4-101; P = .026) and total procedure time (83.2 minutes; 95% confidence interval, 30.1-136.2; P = .002). Active management of surgical team turnover may be an opportunity to improve operating room efficiency when the surgical team is engaged in a major pulmonary resection. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.
Time-dependent problems and difference methods
Gustafsson, Bertil; Oliger, Joseph
2013-01-01
Praise for the First Edition "". . . fills a considerable gap in the numerical analysis literature by providing a self-contained treatment . . . this is an important work written in a clear style . . . warmly recommended to any graduate student or researcher in the field of the numerical solution of partial differential equations."" -SIAM Review Time-Dependent Problems and Difference Methods, Second Edition continues to provide guidance for the analysis of difference methods for computing approximate solutions to partial differential equations for time-de
dependent time-delay: Stability and stabilizability
Directory of Open Access Journals (Sweden)
E. K. Boukas
2002-01-01
Full Text Available This paper considers stochastic stability and stochastic stabilizability of linear discrete-time systems with Markovian jumps and mode-dependent time-delays. Linear matrix inequality (LMI techniques are used to obtain sufficient conditions for the stochastic stability and stochastic stabilizability of this class of systems. A control design algorithm is also provided. A numerical example is given to demonstrate the effectiveness of the obtained theoretical results.
Time-dependent secular evolution in galaxies
Weinberg, M D
2004-01-01
Lynden-Bell & Kalnajs (1972) presented a useful formula for computing the long-range torque between spiral arms and the disk at large. The derivation uses second-order perturbation theory and assumes that the perturbation slowly grows over a very long time: the time-asymptotic limit. This formula has been widely used to predict the angular momentum transport between spiral arms and stellar bars between disks and dark-matter halos. However, this paper shows that the LBK time-asymptotic limit is not appropriate because the characteristic evolution time for galaxies is too close to the relevant dynamical times. We demonstrate that transients, not present in the time-asymptotic formula, can play a major role in the evolution for realistic astronomical time scales. A generalisation for arbitrary time dependence is presented and illustrated by the bar--halo and satellite--halo interaction. The natural time dependence in bar-driven halo evolution causes quantitative differences in the overall torque and qualitat...
Time-Dependent Erosion of Ion Optics
Wirz, Richard E.; Anderson, John R.; Katz, Ira; Goebel, Dan M.
2008-01-01
The accurate prediction of thruster life requires time-dependent erosion estimates for the ion optics assembly. Such information is critical to end-of-life mechanisms such as electron backstreaming. CEX2D was recently modified to handle time-dependent erosion, double ions, and multiple throttle conditions in a single run. The modified code is called "CEX2D-t". Comparisons of CEX2D-t results with LDT and ELT post-tests results show good agreement for both screen and accel grid erosion including important erosion features such as chamfering of the downstream end of the accel grid and reduced rate of accel grid aperture enlargement with time.
Timing intervals using population synchrony and spike timing dependent plasticity
Directory of Open Access Journals (Sweden)
Wei Xu
2016-12-01
Full Text Available We present a computational model by which ensembles of regularly spiking neurons can encode different time intervals through synchronous firing. We show that a neuron responding to a large population of convergent inputs has the potential to learn to produce an appropriately-timed output via spike-time dependent plasticity. We explain why temporal variability of this population synchrony increases with increasing time intervals. We also show that the scalar property of timing and its violation at short intervals can be explained by the spike-wise accumulation of jitter in the inter-spike intervals of timing neurons. We explore how the challenge of encoding longer time intervals can be overcome and conclude that this may involve a switch to a different population of neurons with lower firing rate, with the added effect of producing an earlier bias in response. Experimental data on human timing performance show features in agreement with the model’s output.
Time Circular Birefringence in Time-Dependent Magnetoelectric Media
Zhang, Ruo-Yang; Lin, Shi-Rong; Zhao, Qing; Wen, Weijia; Ge, Mo-Lin
2015-01-01
Light traveling in time-dependent media has many extraordinary properties which can be utilized to convert frequency, achieve temporal cloaking, and simulate cosmological phenomena. In this paper, we focus on time-dependent axion-type magnetoelectric (ME) media, and prove that light in these media always has two degenerate modes with opposite circular polarizations corresponding to one wave vector $\\mathbf{k}$, and name this effect "time circular birefringence" (TCB). By interchanging the status of space and time, the pair of TCB modes can appear simultaneously via "time refraction" and "time reflection" of a linear polarized incident wave at a time interface of ME media. The superposition of the two TCB modes causes the "time Faraday effect", namely the globally unified polarization axes rotate with time. A circularly polarized Gaussian pulse traversing a time interface is also studied. If the wave-vector spectrum of a pulse mainly concentrates in the non-traveling-wave band, the pulse will be trapped with n...
Discrete time queues with phase dependent arrivals
Daigle, J. N.; Lee, Y.; Magalhaes, M. N.
1994-02-01
The queueing behavior of many communication systems is well modeled by a queueing system in which time is slotted, and the number of entities that arrive during a slot is dependent upon the state of a discrete time, discrete state Markov chain. Techniques for analyzing such systems have appeared in the literature from time to time, but distributions have been presented in only rare instances. In this paper, we present the probability generating function (PGF) for joint and marginal buffer occupancy distributions of statistical time division multiplexing systems in this class. We discuss inversion of the PGF using discrete Fourier transforms, and also discuss a simple technique for obtaining moments of the queue length distribution. Numerical results, including queue length distributions for some special cases, are presented.
ToolNet: Holistically-Nested Real-Time Segmentation of Robotic Surgical Tools
Garcia-Peraza-Herrera, Luis C.; Li, Wenqi; Fidon, Lucas; Gruijthuijsen, Caspar; Devreker, Alain; Attilakos, George; Deprest, Jan; Poorten, Emmanuel Vander; Stoyanov, Danail; Vercauteren, Tom; Ourselin, Sebastien
2017-01-01
Real-time tool segmentation from endoscopic videos is an essential part of many computer-assisted robotic surgical systems and of critical importance in robotic surgical data science. We propose two novel deep learning architectures for automatic segmentation of non-rigid surgical instruments. Both methods take advantage of automated deep-learning-based multi-scale feature extraction while trying to maintain an accurate segmentation quality at all resolutions. The two proposed methods encode ...
Transformation of time dependence to linear algebra
Menšík, Miroslav
2005-10-01
Reduced density matrix and memory function in the Nakajima-Zwanzig equation are expanded in properly chosen basis of special functions. This trick completely transforms time dependence to linear algebra. Then, the master equation for memory function is constructed and expanded in the same basis functions. For the model of a simple harmonic oscillator it is shown that this trick introduces infinite partial summation of the memory function in the system-bath interaction.
The Time Dependent CP Violation in Charm
Inguglia, Gianluca
2012-01-01
A model which describes the time-dependent CP formalism in $D^0$ decays has recently been proposed. There it has been highlighted a possible measurement of the angle $\\beta_c$, in the charm unitarity triangle, using the decays $D^0\\to K^+ K^-$ and $D^0\\to \\pi^+ \\pi^-$, and a measurement of the mixing phase $\\phi_{MIX}$. The same method can be used to measure the value of the parameter $x$, one of the two parameters defining charm mixing. We numerically evaluate the impact of a time-dependent analysis in terms of the possible outcomes from present and future experiments. We consider the scenarios of correlated $D^0$ mesons production at the center of mass energy of the $\\Psi(3770)$ at Super$B$, uncorrelated production at the center of mass energy of the $\\Upsilon(4S)$ at Super$B$ and Belle II, and LHCb. Recently a hint of direct CP violation in charm decays was reported by the LHCb collaboration, we estimate the rate of time-dependent asymmetry that could be achieved using their available data, and we generali...
Dissipative time-dependent quantum transport theory.
Zhang, Yu; Yam, Chi Yung; Chen, GuanHua
2013-04-28
A dissipative time-dependent quantum transport theory is developed to treat the transient current through molecular or nanoscopic devices in presence of electron-phonon interaction. The dissipation via phonon is taken into account by introducing a self-energy for the electron-phonon coupling in addition to the self-energy caused by the electrodes. Based on this, a numerical method is proposed. For practical implementation, the lowest order expansion is employed for the weak electron-phonon coupling case and the wide-band limit approximation is adopted for device and electrodes coupling. The corresponding hierarchical equation of motion is derived, which leads to an efficient and accurate time-dependent treatment of inelastic effect on transport for the weak electron-phonon interaction. The resulting method is applied to a one-level model system and a gold wire described by tight-binding model to demonstrate its validity and the importance of electron-phonon interaction for the quantum transport. As it is based on the effective single-electron model, the method can be readily extended to time-dependent density functional theory.
Time-dependent Dyson orbital theory.
Gritsenko, O V; Baerends, E J
2016-08-21
Although time-dependent density functional theory (TDDFT) has become the tool of choice for real-time propagation of the electron density ρ(N)(t) of N-electron systems, it also encounters problems in this application. The first problem is the neglect of memory effects stemming from the, in TDDFT virtually unavoidable, adiabatic approximation, the second problem is the reliable evaluation of the probabilities P(n)(t) of multiple photoinduced ionization, while the third problem (which TDDFT shares with other approaches) is the reliable description of continuum states of the electrons ejected in the process of ionization. In this paper time-dependent Dyson orbital theory (TDDOT) is proposed. Exact TDDOT equations of motion (EOMs) for time-dependent Dyson orbitals are derived, which are linear differential equations with just static, feasible potentials of the electron-electron interaction. No adiabatic approximation is used, which formally resolves the first TDDFT problem. TDDOT offers formally exact expressions for the complete evolution in time of the wavefunction of the outgoing electron. This leads to the correlated probability of single ionization P(1)(t) as well as the probabilities of no ionization (P(0)(t)) and multiple ionization of n electrons, P(n)(t), which formally solves the second problem of TDDFT. For two-electron systems a proper description of the required continuum states appears to be rather straightforward, and both P(1)(t) and P(2)(t) can be calculated. Because of the exact formulation, TDDOT is expected to reproduce a notorious memory effect, the "knee structure" of the non-sequential double ionization of the He atom.
Time dependent mean-field games
Gomes, Diogo A.
2014-01-06
We consider time dependent mean-field games (MFG) with a local power-like dependence on the measure and Hamiltonians satisfying both sub and superquadratic growth conditions. We establish existence of smooth solutions under a certain set of conditions depending both on the growth of the Hamiltonian as well as on the dimension. In the subquadratic case this is done by combining a Gagliardo-Nirenberg type of argument with a new class of polynomial estimates for solutions of the Fokker-Planck equation in terms of LrLp- norms of DpH. These techniques do not apply to the superquadratic case. In this setting we recur to a delicate argument that combines the non-linear adjoint method with polynomial estimates for solutions of the Fokker-Planck equation in terms of L1L1-norms of DpH. Concerning the subquadratic case, we substantially improve and extend the results previously obtained. Furthermore, to the best of our knowledge, the superquadratic case has not been addressed in the literature yet. In fact, it is likely that our estimates may also add to the current understanding of Hamilton-Jacobi equations with superquadratic Hamiltonians.
Constitutive model with time-dependent deformations
DEFF Research Database (Denmark)
Krogsbøll, Anette
1998-01-01
are common in time as well as size. This problem is adressed by means of a new constitutive model for soils. It is able to describe the behavior of soils at different deformation rates. The model defines time-dependent and stress-related deformations separately. They are related to each other and they occur......In many geological and Engineering problems it is necessary to transform information from one scale to another. Data collected at laboratory scale are often used to evaluate field problems on a much larger scale. This is certainly true for geological problems where extreme scale differences...... simultanelously. The model is based on concepts from elasticity and viscoplasticity theories. In addition to Hooke's law for the elastic behavior, the framework for the viscoplastic behavior consists, in the general case (two-dimensional or three-dimensional), of a yield surface, an associated flow rule...
Time-dependent Cooling in Photoionized Plasma
Gnat, Orly
2017-02-01
I explore the thermal evolution and ionization states in gas cooling from an initially hot state in the presence of external photoionizing radiation. I compute the equilibrium and nonequilibrium cooling efficiencies, heating rates, and ion fractions for low-density gas cooling while exposed to the ionizing metagalactic background radiation at various redshifts (z = 0 ‑ 3), for a range of temperatures (108–104 K), densities (10‑7–103 cm‑3), and metallicities (10‑3–2 times solar). The results indicate the existence of a threshold ionization parameter, above which the cooling efficiencies are very close to those in photoionization equilibrium (so that departures from equilibrium may be neglected), and below which the cooling efficiencies resemble those in collisional time-dependent gas cooling with no external radiation (and are thus independent of density).
The time-dependent Gutzwiller approximation
Fabrizio, Michele
2015-03-01
The time-dependent Gutzwiller Approximation (t-GA) is shown to be capable of tracking the off-equilibrium evolution both of coherent quasiparticles and of incoherent Hubbard bands. The method is used to demonstrate that the sharp dynamical crossover observed by time-dependent DMFT in the quench-dynamics of a half-filled Hubbard model can be identified within the t-GA as a genuine dynamical transition separating two distinct physical phases. This result, strictly variational for lattices of infinite coordination number, is intriguing as it actually questions the occurrence of thermalization. Next, we shall present how t-GA works in a multi-band model for V2O3 that displays a first-order Mott transition. We shall show that a physically accessible excitation pathway is able to collapse the Mott gap down and drive off-equilibrium the insulator into a metastable metal phase. Work supported by the European Union, Seventh Framework Programme, under the project GO FAST, Grant Agreement No. 280555.
Time Dependence of Hawking Radiation Entropy
Page, Don N
2013-01-01
If a black hole starts in a pure quantum state and evaporates completely by a unitary process, the von Neumann entropy of the Hawking radiation initially increases and then decreases back to zero when the black hole has disappeared. Here numerical results are given for an approximation to the time dependence of the radiation entropy under an assumption of fast scrambling, for large nonrotating black holes that emit essentially only photons and gravitons. The maximum of the von Neumann entropy then occurs after about 53.81% of the evaporation time, when the black hole has lost about 40.25% of its original Bekenstein-Hawking (BH) entropy (an upper bound for its von Neumann entropy) and then has a BH entropy that equals the entropy in the radiation, which is about 59.75% of the original BH entropy 4 pi M_0^2, or about 7.509 M_0^2 \\approx 6.268\\times 10^{76}(M_0/M_\\odot)^2, using my 1976 calculations that the photon and graviton emission process into empty space gives about 1.4847 times the BH entropy loss of the...
In the time of significant generational diversity - surgical leadership must step up!
Money, Samuel R; O'Donnell, Mark E; Gray, Richard J
2014-02-01
The diverse attitudes and motivations of surgeons and surgical trainees within different age groups present an important challenge for surgical leaders and educators. These challenges to surgical leadership are not unique, and other industries have likewise needed to grapple with how best to manage these various age groups. The authors will herein explore management and leadership for surgeons in a time of age diversity, define generational variations within "Baby-Boomer", "Generation X" and "Generation Y" populations, and identify work ethos concepts amongst these three groups. The surgical community must understand and embrace these concepts in order to continue to attract a stellar pool of applicants from medical school. By not accepting the changing attitudes and motivations of young trainees and medical students, we may disenfranchise a high percentage of potential future surgeons. Surgical training programs will fill, but will they contain the highest quality trainees?
Time dependent friction in a free gas
Fanelli, Cristiano; Sisti, Francesco; Stagno, Gabriele V.
2016-03-01
We consider a body moving in a perfect gas, described by the mean-field approximation and interacting elastically with the body, we study the friction exerted by the gas on the body fixed at constant velocities. The time evolution of the body in this setting was studied in Caprino et al. [Math. Phys. 264, 167-189 (2006)], Caprino et al. [Math. Models Methods Appl. Sci. 17, 1369-1403 (2007)], and Cavallaro [Rend. Mat. Appl. 27, 123-145 (2007)] for object with simple shape; the first study where a simple kind of concavity was considered was in Sisti and Ricciuti [SIAM J. Math. Anal. 46, 3759-3611 (2014)], showing new features in the dynamic but not in the friction term. The case of more general shape of the body was left out for further difficulties, and we believe indeed that there are actually non-trivial issues to be faced for these more general cases. To show this and in the spirit of getting a more realistic perspective in the study of friction problems, in this paper, we focused our attention on the friction term itself, studying its behavior on a body with a more general kind of concavity and fixed at constant velocities. We derive the expression of the friction term for constant velocities, we show how it is time dependent, and we give its exact estimate in time. Finally, we use this result to show the absence of a constant velocity in the actual dynamic of such a body.
Time-dependent Backgrounds Of String Theory
Maloney, A D
2003-01-01
This thesis is devoted to the study of time-dependent backgrounds in string theory. The first chapter contains a brief, non-technical introduction to the subject. In the second chapter quantum field theory in d-dimensional de Sitter space is studied, with an emphasis on the dS/CFT correspondence. We study a one-parameter family of dS-invariant vacua; this bulk vacuum dependence is dual to a deformation of the boundary CFT by a marginal operator. In odd spacetime dimensions the state with no particles on I- has no particles on I+ , implying the absence of particle production. In Kerr-dS, a thermal density matrix is found by tracing over causally inaccessible modes. Assuming Cardy's formula, the microscopic entropy of such a thermal state in the boundary CFT precisely equals the Bekenstein-Hawking value. Next, we construct de Sitter vacua of supercritical string theories in D > 10 dimensions. Compactifying D − 4 of these dimensions on a carefully constructed asymmetric orientifold projects out t...
Dedicated robotics team reduces pre-surgical preparation time
Directory of Open Access Journals (Sweden)
Michael S Lasser
2012-01-01
Statistical Analysis Used: Analysis of variance; Two-sample t-test for unequal variances. Results: The first and last 100 cases were found to have similar age (P=0.27, BMI (P=0.11, and ASA (P=0.09. The average preoperative times were 66. 4 and 53.4 min, respectively (P<0.05. The second 100 patients treated were found to have a significantly shorter preoperative time when compared to the first 100 patients (P<0.05. When the first 100 cases were divided into cohorts of 10 cases the mean preoperative time for the first through fourth cohorts were 80.5, 69.3, 78.8, and 64.7 min, respectively. After treatment of our first 30 patients we found a significant drop in preoperative time. This persisted throughout the remainder of our experience. Conclusions: From the time of patient arrival a number of tasks are accomplished by the non-physician operating room staff during RALRP. The use of a consistent staff can decrease preoperative setup times and, therefore, the overall length of surgery.
Time-dependent correlations in electricity markets
Energy Technology Data Exchange (ETDEWEB)
Alvarez-Ramirez, Jose; Escarela-Perez, Rafael [Departamento de Energia, Universidad Autonoma Metropolitana, Mexico DF, 09340 (Mexico)
2010-03-15
In the last years, many electricity markets were subjected to deregulated operation where prices are set by the action of market participants. In this form, producers and consumers rely on demand and price forecasts to decide their bidding strategies, allocate assets, negotiate bilateral contracts, hedge risks, and plan facility investments. A basic feature of efficient market hypothesis is the absence of correlations between price increments over any time scale leading to random walk-type behavior of prices, so arbitrage is not possible. However, recent studies have suggested that this is not the case and correlations are present in the behavior of diverse electricity markets. In this paper, a temporal quantification of electricity market correlations is made by means of detrended fluctuation and Allan analyses. The approach is applied to two Canadian electricity markets, Ontario and Alberta. The results show the existence of correlations in both demand and prices, exhibiting complex time-dependent behavior with lower correlations in winter while higher in summer. Relatively steady annual cycles in demand but unstable cycles in prices are detected. On the other hand, the more significant nonlinear effects (measured in terms of a multifractality index) are found for winter months, while the converse behavior is displayed during the summer period. In terms of forecasting models, our results suggest that nonlinear recursive models (e.g., feedback NNs) should be used for accurate day-ahead price estimation. In contrast, linear models can suffice for demand forecasting purposes. (author)
European Working Time Directive: implications for surgical training.
LENUS (Irish Health Repository)
Donohoe, C L
2010-02-01
The forthcoming implementation of the European Working Time Directive (EWTD) for non-consultant hospital doctors (NCHDs) poses a number of challenges in the areas of patient care, training, service provision and quality of life for workers. Surgery, as a craft-based speciality, will face a greater impact on training of future surgeons as operating time could be lost to service provision. The EWTD acts a stimulus for reform of current working practices and re-configuration of services. It will necessitate transformation of the way in which surgeons are trained, if current standards are to be maintained.
Frimand Needle Holder Reduces Suturing Time and Surgical Stress When Suturing in Palm Grip.
Frimand Rönnow, Carl-Fredrik; Jeppsson, Bengt; Thorlacius, Henrik
2016-06-01
Purpose The Frimand needle holder (FNH) was developed to facilitate palm grip suturing. In the present study, we wanted to examine the impact of the FNH compared with a conventional Hegar-styled needle holder (HSNH) on suture time and surgical stress. Methods Thirty-two surgeons were enrolled and they performed sets of 3 continuous sutures on a polyurethane pad with premarked insert and exit points and the time for suturing was measured. Surgical stress was quantified by having the surgeons to perform 10 release maneuvers with the FNH and the HSNH on a needle attached to a scale. The scale sent 5 values per second to a computer. The first measurement of each series was regarded as the starting weight and all subsequent measurements were either regarded as neutral, pressure or traction. The sum of these measurements represented total surgical stress. Results We found that all surgeons reduced their median suturing time by 16% when using FNH for palm grip suturing with no difference between junior and senior surgeons. Moreover, it was observed that FNH decreased median surgical stress by 62% for all surgeons performing palm grip suturing compared with a conventional HSNH. Conclusion We conclude that the FNH reduces suture time and surgical stress compared with HSNH when performing palm grip suturing. These findings warrant studies in surgical patients in order to evaluate the potential clinical impact of FNH.
Time dependence of Hawking radiation entropy
Page, Don N.
2013-09-01
If a black hole starts in a pure quantum state and evaporates completely by a unitary process, the von Neumann entropy of the Hawking radiation initially increases and then decreases back to zero when the black hole has disappeared. Here numerical results are given for an approximation to the time dependence of the radiation entropy under an assumption of fast scrambling, for large nonrotating black holes that emit essentially only photons and gravitons. The maximum of the von Neumann entropy then occurs after about 53.81% of the evaporation time, when the black hole has lost about 40.25% of its original Bekenstein-Hawking (BH) entropy (an upper bound for its von Neumann entropy) and then has a BH entropy that equals the entropy in the radiation, which is about 59.75% of the original BH entropy 4πM02, or about 7.509M02 ≈ 6.268 × 1076(M0/Msolar)2, using my 1976 calculations that the photon and graviton emission process into empty space gives about 1.4847 times the BH entropy loss of the black hole. Results are also given for black holes in initially impure states. If the black hole starts in a maximally mixed state, the von Neumann entropy of the Hawking radiation increases from zero up to a maximum of about 119.51% of the original BH entropy, or about 15.018M02 ≈ 1.254 × 1077(M0/Msolar)2, and then decreases back down to 4πM02 = 1.049 × 1077(M0/Msolar)2.
Ponce, Brent A; Menendez, Mariano E; Oladeji, Lasun O; Fryberger, Charles T; Dantuluri, Phani K
2014-11-01
The authors describe the first surgical case adopting the combination of real-time augmented reality and wearable computing devices such as Google Glass (Google Inc, Mountain View, California). A 66-year-old man presented to their institution for a total shoulder replacement after 5 years of progressive right shoulder pain and decreased range of motion. Throughout the surgical procedure, Google Glass was integrated with the Virtual Interactive Presence and Augmented Reality system (University of Alabama at Birmingham, Birmingham, Alabama), enabling the local surgeon to interact with the remote surgeon within the local surgical field. Surgery was well tolerated by the patient and early surgical results were encouraging, with an improvement of shoulder pain and greater range of motion. The combination of real-time augmented reality and wearable computing devices such as Google Glass holds much promise in the field of surgery.
What makes polymer crystallization depend on time
Piccarolo, Stefano
2015-12-01
Here we report a series of objections to the mechanism of polymer crystallization by secondary nucleation plausible for very mild cooling conditions, i.e. when solidification time is long enough or when the molecular weight, M, is not too large, conditions not preventing segregation at the growth front to take place. With a manichean approach, if otherwise time is controlling, e.g. in polymer processing, or M is large, segregation is precluded and accumulation of topological defects takes place in the amorphous phase preventing sequential growth of crystalline domains. A non crystalline phase forms very much departed from equilibrium, constrained by the crystalline domains and frozen to an extent dependent on the morphology developed. Consequences are discussed, themselves a proof that segregation simplifies topology when crystallization conditions are mild. A situation responsible for the often reported memory effects as well as for mechanical and rheological properties. Results collected from our own experimental evidence by the originally developed Continuous Cooling Transformation are discussed within this framework and related to the broad, albeit often overlooked, literature on subjects intimately connected to crystallization and therefore spanning different fields of polymer science. We focus our attention on two recent results opening the way to this new perspective on polymer crystallization: the onset of the nodular morphology in iPP also in the presence of the stable a-monoclinic phase and the extended crystallization behaviour of polyester blends once local mobility is enhanced. Observing that demixing at the growth front controls crystallization under processing conditions we speculate that the high cooling rate solidification experiment is but a peculiar transient rheological measurement. Implications of this view are far reaching as the crucial role of the melt before solidification is evident.
Studies of Spuriously Time-dependent Resonances in Time-dependent Density Functional Theory
Luo, Kai; Maitra, Neepa T
2016-01-01
Adiabatic approximations in time-dependent density functional theory (TDDFT) will in general yield unphysical time-dependent shifts in the resonance positions of a system driven far from its ground-state. This spurious time-dependence is rationalized in [J. I. Fuks, K. Luo, E. D. Sandoval and N. T. Maitra, Phys. Rev. Lett. {\\bf 114}, 183002 (2015)] in terms of the violation of an exact condition by the non-equilibrium exchange-correlation kernel of TDDFT. Here we give details on the derivation and discuss reformulations of the exact condition that apply in special cases. In its most general form, the condition states that when a system is left in an arbitrary state, in the absence of time-dependent external fields nor ionic motion, the TDDFT resonance position for a given transition is independent of the state. Special cases include the invariance of TDDFT resonances computed with respect to any reference interacting stationary state of a fixed potential, and with respect to any choice of appropriate stationa...
Directory of Open Access Journals (Sweden)
Chih-Yuan Lin
2014-01-01
Full Text Available Background: Coronary artery disease occurs frequently and is a major cause of morbidity and mortality in patients with chronic renal failure. Because the number of patients requiring dialysis for end-stage renal disease (ESRD has increased, the number of patients in this population who require coronary artery bypass grafting (CABG has increased. The aim of this study was to examine the effect of early hemodialysis (HD on the early surgical outcomes of ESRD patients undergoing CABG. Materials and Methods: Fifty-nine dialysis-dependent patients who underwent isolated CABG with cardiopulmonary bypass (CPB were enrolled in this study. These patients were divided into two groups based on the timing of the first postoperation HD session. In the early HD group, HD was performed within 6 h postoperation; in the scheduled HD group, HD was performed >6 h postoperation. The preoperative characteristics, operative variables, and postoperative outcomes were retrospectively analyzed. Results: The time to first HD after CABG was 2.43 ± 1.58 h in the early HD group and 20.68 ± 6.98 h in the scheduled HD group (P < 0.001. There were no significant differences in the operative variables, namely duration of operation, CPB time, and aortic cross-clamp time, between the two groups. The incidence of postoperative pneumonia was higher in the scheduled HD group (31.8% than in the early HD group (2.7%. There was a trend of decreased incidence of postoperative pneumonia in the early HD group with marginal significance from the univariate analysis. The intensive care unit and hospital stay duration of both groups were similar. Nine patients died in the hospital, yielding an overall 30-day mortality of 8.47%. Conclusion: In dialysis-dependent patients who underwent CABG, the short-term outcomes and surgical mortality were acceptable. Dialysis-dependent renal failure should not be considered a contraindication for CABG. Early HD in the postoperative period demonstrated
Supply and demand mismatch for flexible (part-time) surgical training in Australasia.
McDonald, Rachel E; Jeeves, Amy E; Vasey, Carolyn E; Wright, Deborah M; O'Grady, Gregory
2013-05-06
To define current patterns of flexible (part-time) surgical training in Australasia, determine supply and demand for part-time positions, and identify work-related factors motivating interest in flexible training. All Royal Australasian College of Surgeons trainees (n = 1191) were surveyed in 2010. Questions assessed demographic characteristics and working patterns, interest in flexible training, work-related fatigue and work-life balance preferences. Interest in part-time training, and work-related factors motivating this interest. Of the 1191 trainees, 659 responded (response rate, 55.3%). Respondents were representative of all trainees in terms of specialty and sex. The median age of respondents was 32 2013s, and 187 (28.4%) were female. Most of the 659 respondents (627, 95.1%) were in full-time clinical training; only two (0.3%) were in part-time clinical training, and 30 (4.6%) were not in active clinical training. An interest in part-time training was reported by 208 respondents (31.6%; 54.3% of women v 25.9% of men; P work and limited their social or family life, and that they had insufficient time in life for things outside surgical training, including study or research (P flexible surgical training and the number of trainees currently in part-time training positions in Australia and New Zealand. Efforts are needed to facilitate part-time surgical training.
Time-dependence in mixture toxicity prediction.
Dawson, Douglas A; Allen, Erin M G; Allen, Joshua L; Baumann, Hannah J; Bensinger, Heather M; Genco, Nicole; Guinn, Daphne; Hull, Michael W; Il'Giovine, Zachary J; Kaminski, Chelsea M; Peyton, Jennifer R; Schultz, T Wayne; Pöch, Gerald
2014-12-04
The value of time-dependent toxicity (TDT) data in predicting mixture toxicity was examined. Single chemical (A and B) and mixture (A+B) toxicity tests using Microtox(®) were conducted with inhibition of bioluminescence (Vibrio fischeri) being quantified after 15, 30 and 45-min of exposure. Single chemical and mixture tests for 25 sham (A1:A2) and 125 true (A:B) combinations had a minimum of seven duplicated concentrations with a duplicated control treatment for each test. Concentration/response (x/y) data were fitted to sigmoid curves using the five-parameter logistic minus one parameter (5PL-1P) function, from which slope, EC25, EC50, EC75, asymmetry, maximum effect, and r(2) values were obtained for each chemical and mixture at each exposure duration. Toxicity data were used to calculate percentage-based TDT values for each individual chemical and mixture of each combination. Predicted TDT values for each mixture were calculated by averaging the TDT values of the individual components and regressed against the observed TDT values obtained in testing, resulting in strong correlations for both sham (r(2)=0.989, n=25) and true mixtures (r(2)=0.944, n=125). Additionally, regression analyses confirmed that observed mixture TDT values calculated for the 50% effect level were somewhat better correlated with predicted mixture TDT values than at the 25 and 75% effect levels. Single chemical and mixture TDT values were classified into five levels in order to discern trends. The results suggested that the ability to predict mixture TDT by averaging the TDT of the single agents was modestly reduced when one agent of the combination had a positive TDT value and the other had a minimal or negative TDT value. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Time-dependent constrained Hamiltonian systems and Dirac brackets
Energy Technology Data Exchange (ETDEWEB)
Leon, Manuel de [Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Madrid (Spain); Marrero, Juan C. [Departamento de Matematica Fundamental, Facultad de Matematicas, Universidad de La Laguna, La Laguna, Tenerife, Canary Islands (Spain); Martin de Diego, David [Departamento de Economia Aplicada Cuantitativa, Facultad de Ciencias Economicas y Empresariales, UNED, Madrid (Spain)
1996-11-07
In this paper the canonical Dirac formalism for time-dependent constrained Hamiltonian systems is globalized. A time-dependent Dirac bracket which reduces to the usual one for time-independent systems is introduced. (author)
A time-dependent model for improved biogalvanic tissue characterisation.
Chandler, J H; Culmer, P R; Jayne, D G; Neville, A
2015-10-01
Measurement of the passive electrical resistance of biological tissues through biogalvanic characterisation has been proposed as a simple means of distinguishing healthy from diseased tissue. This method has the potential to provide valuable real-time information when integrated into surgical tools. Characterised tissue resistance values have been shown to be particularly sensitive to external load switching direction and rate, bringing into question the stability and efficacy of the technique. These errors are due to transient variations observed in measurement data that are not accounted for in current electrical models. The presented research proposes the addition of a time-dependent element to the characterisation model to account for losses associated with this transient behaviour. Influence of switching rate has been examined, with the inclusion of transient elements improving the repeatability of the characterised tissue resistance. Application of this model to repeat biogalvanic measurements on a single ex vivo human colon tissue sample with healthy and cancerous (adenocarcinoma) regions showed a statistically significant difference (p 0.05) between tissue types was found when measurements were subjected to the current model, suggesting that the proposed model may allow for improved biogalvanic tissue characterisation. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.
Lee, Changho; Kim, Kyungun; Han, Seunghoon; Kim, Sehui; Lee, Jun Hoon; Kim, Hong kyun; Kim, Chulhong; Jung, Woonggyu; Kim, Jeehyun
2014-01-01
Abstract. An intraoperative surgical microscope is an essential tool in a neuro- or ophthalmological surgical environment. Yet, it has an inherent limitation to classify subsurface information because it only provides the surface images. To compensate for and assist in this problem, combining the surgical microscope with optical coherence tomography (OCT) has been adapted. We developed a real-time virtual intraoperative surgical OCT (VISOCT) system by adapting a spectral-domain OCT scanner with a commercial surgical microscope. Thanks to our custom-made beam splitting and image display subsystems, the OCT images and microscopic images are simultaneously visualized through an ocular lens or the eyepiece of the microscope. This improvement helps surgeons to focus on the operation without distraction to view OCT images on another separate display. Moreover, displaying the OCT live images on the eyepiece helps surgeon’s depth perception during the surgeries. Finally, we successfully processed stimulated penetrating keratoplasty in live rabbits. We believe that these technical achievements are crucial to enhance the usability of the VISOCT system in a real surgical operating condition. PMID:24604471
Referral for a bariatric surgical consultation: it is time to set a standard of care.
Dixon, John B
2009-05-01
Indications for bariatric surgery have been clear for some time and many would say that they are conservative. Unfortunately few eligible candidates seek or are referred for bariatric surgery, with less than 1% currently treated annually. In recent years, the evidence base supporting surgical therapy has strengthened with demonstrable improvements in both safety and efficacy. We now have evidence of remarkable improvements in health, quality of life, and increased life expectancy. There is continued frustration with the poor efficacy of non-surgical therapies and no indication that this is about to change. A caring physician should, as best care, refer the seriously ill morbidly obese patient for a surgical opinion. It is no different from their obligation to adequately manage type-2 diabetes, depression or unstable angina. Currently, even discussion of a surgical referral is optional. It is time we articulated and defined a group of patients where referral for a surgical opinion is no longer merely an option but a physician's responsibility as best care for the patient. It is time to provide leadership towards the delivery of better care for these patients.
Production Planning with Load Dependent Lead Times
DEFF Research Database (Denmark)
Pahl, Julia
2005-01-01
Lead times impact the performance of the supply chain significantly. Although there is a large literature concerning queuing models for the analysis of the relationship between capacity utilization and lead times, and there is a substantial literature concerning control and order release policies...... that take lead times into consideration, there have been only few papers describing models at the aggregate planning level that recognize the relationship between the planned utilization of capacity and lead times. In this paper we provide an in-depth discussion of the state-of-the art in this literature...
Load Dependent Lead Times and Sustainability
DEFF Research Database (Denmark)
Pahl, Julia; Voss, Stefan
2016-01-01
to prevent decreased quality or waste of production parts and products. This gains importance because waiting times imply longer lead times charging the production system with work in process inventories. Longer lead times can lead to quality losses due to depreciation, so that parts need to be reworked...... if possible or discarded. But return flows of products for rework or remanufacturing actions significantly complicate the production planning process. We analyze sustainability options with respect to lead time management by formulating a comprehensive mathematical model. We consider a deterministic, mixed...
Continuous-Time Modeling with Spatial Dependence
Oud, J.H.L.; Folmer, H.; Patuelli, R.; Nijkamp, P.
2012-01-01
(Spatial) panel data are routinely modeled in discrete time (DT). However, compelling arguments exist for continuous-time (CT) modeling of (spatial) panel data. Particularly, most social processes evolve in CT, so that statistical analysis in DT is an oversimplification, gives an incomplete
Continuous-Time Modeling with Spatial Dependence
Oud, J.; Folmer, H.; Patuelli, R.; Nijkamp, P.
(Spatial) panel data are routinely modeled in discrete time (DT). However, compelling arguments exist for continuous-time (CT) modeling of (spatial) panel data. Particularly, most social processes evolve in CT, so that statistical analysis in DT is an oversimplification, gives an incomplete
Dunn, John C; Belmont, Philip J; Lanzi, Joseph; Martin, Kevin; Bader, Julia; Owens, Brett; Waterman, Brian R
2015-01-01
Surgical education is evolving as work hour constraints limit the exposure of residents to the operating room. Potential consequences may include erosion of resident education and decreased quality of patient care. Surgical simulation training has become a focus of study in an effort to counter these challenges. Previous studies have validated the use of arthroscopic surgical simulation programs both in vitro and in vivo. However, no study has examined if the gains made by residents after a simulation program are retained after a period away from training. In all, 17 orthopedic surgery residents were randomized into simulation or standard practice groups. All subjects were oriented to the arthroscopic simulator, a 14-point anatomic checklist, and Arthroscopic Surgery Skill Evaluation Tool (ASSET). The experimental group received 1 hour of simulation training whereas the control group had no additional training. All subjects performed a recorded, diagnostic arthroscopy intraoperatively. These videos were scored by 2 blinded, fellowship-trained orthopedic surgeons and outcome measures were compared within and between the groups. After 1 year in which neither group had exposure to surgical simulation training, all residents were retested intraoperatively and scored in the exact same fashion. Individual surgical case logs were reviewed and surgical case volume was documented. There was no difference between the 2 groups after initial simulation testing and there was no correlation between case volume and initial scores. After training, the simulation group improved as compared with baseline in mean ASSET (p = 0.023) and mean time to completion (p = 0.01). After 1 year, there was no difference between the groups in any outcome measurements. Although individual technical skills can be cultivated with surgical simulation training, these advancements can be lost without continued education. It is imperative that residency programs implement a simulation curriculum and
Time dependent deformation of Kilauea Volcano, Hawaii
Montgomery-Brown, Emily Kvietka Desmarais
to a decollement structure 8 km under the south flank, and the locations of the microearthquakes suggest that both occur on the same structure. In 2007, Episode 56 of the Pu'u 'O'o-Kupianaha eruption occurred. This episode was exciting both because it was the largest intrusion in the last decade, and because it occurred concurrently with a flank slow-slip event. The intrusion started on Father's day (June 17th), 2007 with increased seismicity and abrupt tilts at the summit and rift zones. Quasi-static models of the total deformation determined from GPS, tilt, and InSAR indicate that the intrusion occurred on two en echelon dike segments in the upper East Rift Zone along with deformation consistent with slow-slip in the same areas of previous events. The ˜ 2 m maximum opening occurred on the eastern segment near Makaopui crater. Unlike previous intrusions in 1997, 1999, and 2000, the dike model was not sufficient to explain deformation on the western flank. Additionally, a coastal tiltmeter installed in anticipation of a slow-slip event recorded tilts consistent with those observed during the 2005 slow-slip event. These observations led to the conclusion that a concurrent slow-slip event occurred. Geodetic models indicate a similar amount of decollement slip occurred as in previous slow-slip events. Sub-daily GPS positions were used to study the spatio-temporal distribution of the dike intrusion. The time-dependent intrusion model shows that the intrusion began on the western en echelon segment before jumping to the eastern segment, which accumulated the majority of the 2 m of opening. Sub-daily GPS positions limit the number of stations available since there are very few continuous stations north of the East Rift Zone, where coverage is critical for separating the intrusion from the slow-slip. However, an ENVISAT interferogram at 08:22 on June 18, 2007 provides additional spatial coverage of deformation up to that point. Combining this image with the GPS and tilt
Real-time stereo generation for surgical vision during minimal invasive robotic surgery
Laddi, Amit; Bhardwaj, Vijay; Mahapatra, Prasant; Pankaj, Dinesh; Kumar, Amod
2016-03-01
This paper proposes a framework for 3D surgical vision for minimal invasive robotic surgery. It presents an approach for generating the three dimensional view of the in-vivo live surgical procedures from two images captured by very small sized, full resolution camera sensor rig. A pre-processing scheme is employed to enhance the image quality and equalizing the color profile of two images. Polarized Projection using interlacing two images give a smooth and strain free three dimensional view. The algorithm runs in real time with good speed at full HD resolution.
Time dependences of atmospheric Carbon dioxide fluxes
DeSalvo, Riccardo
2014-01-01
Understanding the lifetime of CO2 in the atmosphere is critical for predictions regarding future climate changes. A simple mass conservation analysis presented here generates tight estimations for the atmosphere's retention time constant. The analysis uses a leaky integrator model that combines the observed deficit (only less than 40% of CO2 produced from combustion of fossil fuels is actually retained in the atmosphere, while more than 60% is continuously shed) with the exponential growth of fossil fuel burning. It reveals a maximum characteristic time of less than 23 year for the transfer of atmospheric CO2 to a segregation sink. This time constant is further constrained by the rapid disappearance of 14C after the ban of atmospheric atomic bomb tests, which provides a lower limit of 18 years for this transfer. The study also generates evaluations of other CO2 fluxes, exchange time constants and volumes exchanged. Analysis of large harmonic oscillations of atmospheric CO2 concentration, often neglected in th...
Institute of Scientific and Technical Information of China (English)
MA Ren-shi; GU Gui-shan; WANG Cheng-xue; ZHU Dong; ZHANG Xi-zheng
2010-01-01
Objective:To elucidate the relationship between surgical time and postoperative complications in senile patients with hip fractures, and try to find out other factors which are related to these complications.Methods: Sixty-two patients, 28 males aged from 65 to 72 years with a mean age of 76.3 years and 34 females aged from 65 to 95 years with a mean age of 78.1 years, who had undergone orthopedic surgery because of hip fractures,were enrolled in a retrospective cohort study. The surgical time and pattern, the type of fracture, preoperative comorbidities, American Society of Anesthesiologists (ASA) score and the volume of blood transfusion during operation were obtained from these patients who were followed up by telephone calls for postoperative complications.All the patients were followed up at least for 1 year and were divided into subgroups according to their clinical characteristics and the results were analyzed by the Statistical Analysis System software.Results:There was no significant difference in the morbidity of postoperative eomplications with the gender,age,surgical time and pattern,or ASA score. There was significant difference in the morbidity of postoperative complications related to preoperative comorbidities and the volume of blood transfusion. There was a significant causality between preoperative comorbidities and postoperative complications. The morbidity of postoperative complications was 1.651 times higher in patients with preoperative comorbidities than those without.Conclusions:There is no relationship between the surgical time and postoperative complications in senile patients who received surgery for hip fracture within 1 year.No correlation is found between the postoperative complications and gender,age,type of fracture, surgical pattern,ASA score and the volume of blood transfusion. Preoperative comorbidities are an independent predictor for postoperative complications.
Coordinate time dependence in Quantum Gravity
Bojowald, M; Skirzewski, A; Bojowald, Martin; Singh, Parampreet; Skirzewski, Aureliano
2004-01-01
The intuitive classical space-time picture breaks down in quantum gravity, which makes a comparison and the development of semiclassical techniques quite complicated. Using ingredients of the group averaging method to solve constraints one can nevertheless introduce a classical coordinate time into the quantum theory, and use it to investigate the way a semiclassical continuous description emerges from discrete quantum evolution. Applying this technique to test effective classical equations of loop cosmology and their implications for inflation and bounces, we show that the effective semiclassical theory is in good agreement with the quantum description even at short scales.
National Research Council Canada - National Science Library
Matsuo, Koji; Opper, Neisha R; Ciccone, Marcia A; Garcia, Jocelyn; Tierney, Katherine E; Baba, Tsukasa; Muderspach, Laila I; Roman, Lynda D
2015-01-01
OBJECTIVE:To examine whether wait time between endometrial biopsy and surgical staging correlates with tumor characteristics and affects survival outcomes in patients with type I endometrial cancer...
STUDY OF THE TIME DEPENDENCE OF RADIOACTIVITY
Directory of Open Access Journals (Sweden)
E Bellotti
2013-12-01
Full Text Available The activity of a 137Cs source was measured using a germanium detector installed deep underground in the Gran Sasso Laboratory. In total about 5100 energy spectra, one hour measuring time each, were collected and used to search for time variations of the decay constant with periods from a few hours to 1 year. No signal with amplitude larger than 9.6 × 10−5 at 95% C.L. was detected. These limits are more than one order of magnitude lower than the values on the oscillation amplitude reported in the literature. The same data give a value of 29.96±0.08 years for the 137Cs half life, which is in good agreement with the world mean value of 30.05 ± 0.08 years.
Williams, Catherine; Johnson, Pat A; Guzzetta, Cathie E; Guzzetta, Philip C; Cohen, Ira Todd; Sill, Anne M; Vezina, Gilbert; Cain, Sherry; Harris, Christine; Murray, Jodi
2014-01-01
Prolonged preoperative fasting can be associated with adverse outcomes, particularly in children. Our aims were to assess the time pediatric patients fasted prior to surgical or radiologic procedures and evaluate whether fasting (NPO) orders complied with national guidelines. We measured NPO start time, time of last intake, and time test or surgery was scheduled, took place, or was cancelled in 219 pediatric patients. Findings demonstrate that pediatric patients experienced prolonged fasting before procedures and that the majority of NPO orders were non-compliant with national guidelines. We have developed strategies to reduce fasting times and ensure compliance with recommended national fasting standards.
Nonlinear time dependent behaviour of epoxy resins
Marotzke, C.; Feldmann, T.
2016-07-01
The nonlinear behaviour of epoxy resins is studied on standard tensile tests. A strain field measurement system is applied (Aramis) in order to monitor local strains. The residual strain is measured by recovering the specimens for up to 68 hours after unloading. The time span the specimen is exposed to load has a large influence on the creeping process and the residual strain after recovering. This is studied by comparison of instantaneous unloading with keeping the specimen under permanent load for thirty minutes. It is shown that moderate differences in the initial strain can lead to large differences in the creep behaviour as well as in the residual strain.
Time Dependent Data Mining in RAVEN
Energy Technology Data Exchange (ETDEWEB)
Cogliati, Joshua Joseph [Idaho National Lab. (INL), Idaho Falls, ID (United States); Chen, Jun [Idaho National Lab. (INL), Idaho Falls, ID (United States); Patel, Japan Ketan [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Maljovec, Daniel Patrick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Talbot, Paul William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2016-09-01
RAVEN is a generic software framework to perform parametric and probabilistic analysis based on the response of complex system codes. The goal of this type of analyses is to understand the response of such systems in particular with respect their probabilistic behavior, to understand their predictability and drivers or lack of thereof. Data mining capabilities are the cornerstones to perform such deep learning of system responses. For this reason static data mining capabilities were added last fiscal year (FY 15). In real applications, when dealing with complex multi-scale, multi-physics systems it seems natural that, during transients, the relevance of the different scales, and physics, would evolve over time. For these reasons the data mining capabilities have been extended allowing their application over time. In this writing it is reported a description of the new RAVEN capabilities implemented with several simple analytical tests to explain their application and highlight the proper implementation. The report concludes with the application of those newly implemented capabilities to the analysis of a simulation performed with the Bison code.
Directory of Open Access Journals (Sweden)
Dante A. Guevara-Villarreal
2016-01-01
Full Text Available Ocular penetrating injury with Intraocular Foreign Body (IOFB is a common form of ocular injury. Several techniques to remove IOFB have been reported by different authors. The aim of this publication is to review different timing and surgical techniques related to the extraction of IOFB. Material and Methods. A PubMed search on “Extraction of Intraocular Foreign Body,” “Timing for Surgery Intraocular Foreign Body,” and “Surgical Technique Intraocular Foreign Body” was made. Results. Potential advantages of immediate and delayed IOFB removal have been reported with different results. Several techniques to remove IOFB have been reported by different authors with good results. Conclusion. The most important factor at the time to perform IOFB extraction is the experience of the surgeon.
Saturation and time dependence of geodynamo models
Schrinner, M; Cameron, R; Hoyng, P
2009-01-01
In this study we address the question under which conditions a saturated velocity field stemming from geodynamo simulations leads to an exponential growth of the magnetic field in a corresponding kinematic calculation. We perform global self-consistent geodynamo simulations and calculate the evolution of a kinematically advanced tracer field. The self-consistent velocity field enters the induction equation in each time step, but the tracer field does not contribute to the Lorentz force. This experiment has been performed by Cattaneo & Tobias (2009) and is closely related to the test field method by Schrinner et al. (2005, 2007). We find two dynamo regimes in which the tracer field either grows exponentially or approaches a state aligned with the actual self-consistent magnetic field after an initial transition period. Both regimes can be distinguished by the Rossby number and coincide with the dipolar and multipolar dynamo regimes identified by Christensen & Aubert (2006). Dipolar dynamos with low Ros...
Heart valve surgery in hemodialysis-dependent patients: nutrition status impact on surgical outcome.
Kawahito, Koji; Aizawa, Kei; Oki, Shinichi; Saito, Tsutomu; Misawa, Yoshio
2016-06-01
Valve surgery in hemodialysis-dependent patients is associated with postoperative complications and a high mortality rate, and such patients frequently suffer cachexia. This study aimed to determine pre- and intraoperative risk factors associated with in-hospital mortality and long-term survival in hemodialysis-dependent patients undergoing heart valve surgery from the viewpoint of nutrition status. Eighty-seven hemodialysis-dependent patients who underwent valve surgery between January 1998 and October 2015 were retrospectively reviewed. Thirty-seven potential perioperative risk factors were evaluated. The in-hospital mortality rate was 12.6 % (11 patients). Univariate analysis identified New York Heart Association Functional Classification III or IV, emaciation (body mass index 3000 ml as predictors of in-hospital death. Multivariate logistic regression analysis confirmed low serum albumin <3.0 mg/dl (hazard ratio 7.22; p = 0.032) and emergent/urgent operation (hazard ratio 43.57; p = 0.035) as independent predictors of in-hospital death. The 1- and 3-year actuarial survival rates were 64.9 ± 5.4 and 51.8 ± 5.8 %, respectively. Long-term survival estimated by log-rank test was negatively impacted by anemia (hemoglobin <10 mg/dl), low serum albumin, emergent/urgent operation, and infective endocarditis. Multivariate analysis using Cox proportional hazards modeling indicated low serum albumin (hazard ratio 2.12; p = 0.047) and emergent/urgent operation (hazard ratio 8.97; p = 0.0002) as independent predictors of remote death. Hypoalbuminemia and emergent/urgent operation are strong predictors of in-hospital and remote death. Malnutrition before surgery should be considered for operative risk estimation, and adequate preoperative nutrition management may improve surgical outcomes for hemodialysis-dependent patients.
Computing Resolution-Path Dependencies in Linear Time
Slivovsky, Friedrich
2012-01-01
The alternation of existential and universal quantifiers in a quantified boolean formula (QBF) generates dependencies among variables that must be respected when evaluating the formula. Dependency schemes provide a general framework for representing such dependencies. Since it is generally intractable to determine dependencies exactly, a set of potential dependencies is computed instead, which may include false positives. Among the schemes proposed so far, resolution-path dependencies introduce the fewest spurious dependencies. In this work, we describe an algorithm that detects resolution-path dependencies in linear time, resolving a problem posed by Van Gelder (CP 2011)
Institute of Scientific and Technical Information of China (English)
Axel Schulze-Halberg
2005-01-01
We study space-time transformations of the time-dependent Schr(o)dinger equation (TDSE) with time- and position-dependent (effective) mass. We obtain the most general space-time transformation that maps such a TDSE onto another one of its kind. The transformed potential is given in explicit form.
Significance and management of positive surgical margins at the time of radical prostatectomy.
Silberstein, Jonathan L; Eastham, James A
2014-10-01
Positive surgical margins (PSM) at the time of radical prostatectomy (RP) result in an increased risk of biochemical recurrence (BCR) and secondary treatment. We review current literature with a focus on stratifying the characteristics of the PSM that may define its significance, the impact of modern imaging and surgical approaches in avoidance of PSM, and management strategies when PSM do occur. We performed a review of the available literature to identify factors associated with PSM and their management. PSM have been repeatedly demonstrated to be associated with an increased risk of BCR following RP. The specific characteristics (size, number, location, Gleason score at the margin) of the PSM may influence the risk of recurrence. Novel imaging and surgical approaches are being investigated and may allow for reductions of PSM in the future. The use of adjuvant treatment for a PSM remains controversial and should be decided on an individual basis after a discussion about the risks and benefits. The goal of RP is complete resection of the tumor. PSM are associated with increased risk of BCR and secondary treatments. Of the risk factors associated with BCR after RP, a PSM is directly influenced by surgical technique.
K shortest paths in stochastic time-dependent networks
DEFF Research Database (Denmark)
Nielsen, Lars Relund; Pretolani, Daniele; Andersen, Kim Allan
2004-01-01
A substantial amount of research has been devoted to the shortest path problem in networks where travel times are stochastic or (deterministic and) time-dependent. More recently, a growing interest has been attracted by networks that are both stochastic and time-dependent. In these networks...
Real-time segmentation and recognition of surgical tasks in cataract surgery videos.
Quellec, Gwénolé; Lamard, Mathieu; Cochener, Béatrice; Cazuguel, Guy
2014-12-01
In ophthalmology, it is now common practice to record every surgical procedure and to archive the resulting videos for documentation purposes. In this paper, we present a solution to automatically segment and categorize surgical tasks in real-time during the surgery, using the video recording. The goal would be to communicate information to the surgeon in due time, such as recommendations to the less experienced surgeons. The proposed solution relies on the content-based video retrieval paradigm: it reuses previously archived videos to automatically analyze the current surgery, by analogy reasoning. Each video is segmented, in real-time, into an alternating sequence of idle phases, during which no clinically-relevant motions are visible, and action phases. As soon as an idle phase is detected, the previous action phase is categorized and the next action phase is predicted. A conditional random field is used for categorization and prediction. The proposed system was applied to the automatic segmentation and categorization of cataract surgery tasks. A dataset of 186 surgeries, performed by ten different surgeons, was manually annotated: ten possibly overlapping surgical tasks were delimited in each surgery. Using the content of action phases and the duration of idle phases as sources of evidence, an average recognition performance of Az = 0.832 ± 0.070 was achieved.
Introduction to numerical methods for time dependent differential equations
Kreiss, Heinz-Otto
2014-01-01
Introduces both the fundamentals of time dependent differential equations and their numerical solutions Introduction to Numerical Methods for Time Dependent Differential Equations delves into the underlying mathematical theory needed to solve time dependent differential equations numerically. Written as a self-contained introduction, the book is divided into two parts to emphasize both ordinary differential equations (ODEs) and partial differential equations (PDEs). Beginning with ODEs and their approximations, the authors provide a crucial presentation of fundamental notions, such as the t
Reorganizing nursing work on surgical units: a time-and-motion study.
Desjardins, France; Cardinal, Linda; Belzile, Eric; McCusker, Jane
2008-01-01
A time-and-motion study was conducted in response to perceptions that the surgical nursing staff at a Montreal hospital was spending an excessive amount of time on non-nursing care. A sample of 30 nurse shifts was observed by trained observers who timed nurses' activities for their entire working shift using a hand-held Personal Digital Assistant. Activities were grouped into four main categories: direct patient care, indirect patient care, non-nursing and personal activities. Break and meal times were excluded from the denominator of total worked hours. A total of 201 working hours were observed, an average of 6 hours, 42 minutes per nurse shift. The mean proportions of each nurse shift spent on the main activity categories were: direct care 32.8%, indirect care 55.7%, non-nursing tasks 9.0% and personal 2.5%. Three activities (communication among health professionals, medication verification/preparation and documentation) comprised 78.9% of indirect care time. Greater time on indirect care was associated with work on night shifts and on the short-stay surgical unit. Subsequent work reorganization focused on reducing time spent on communication and medications. The authors conclude that time-and-motion studies are a useful method of monitoring appropriate use of nursing staff, and may provide results that assist in restructuring nursing tasks.
Random Time Dependent Resistance Analysis on Reinforced Concrete Structures
Institute of Scientific and Technical Information of China (English)
GUAN Chang-sheng; WU Ling
2002-01-01
The analysis method on random time dependence of reinforced concrete material is introduced,the effect mechanism on reinforced concrete are discussed, and the random time dependence resistance of reinforced concrete is studied. Furthermore, the corrosion of steel bar in reinforced concrete structures is analyzed. A practical statistical method of evaluating the random time dependent resistance, which includes material, structural size and calculation influence, is also established. In addition, an example of predicting random time dependent resistance of reinforced concrete structural element is given.
The sigmoid volvulus: surgical timing and mortality for different clinical types
Directory of Open Access Journals (Sweden)
Spizzirri Alessandro
2010-01-01
Full Text Available Abstract Background In western countries intestinal obstruction caused by sigmoid volvulus is rare and its mortality remains significant in patients with late diagnosis. The aim of this work is to assess what is the correct surgical timing and how the prognosis changes for the different clinical types. Methods We realized a retrospective clinical study including all the patients treated for sigmoid volvulus in the Department of General Surgery, St Maria Hospital, Terni, from January 1996 till January 2009. We selected 23 patients and divided them in 2 groups on the basis of the clinical onset: patients with clear clinical signs of obstruction and patients with subocclusive symptoms. We focused on 30-day postoperative mortality in relation to the surgical timing and procedure performed for each group. Results In the obstruction group mortality rate was 44% and it concerned only the patients who had clinical signs and symptoms of peritonitis and that were treated with a sigmoid resection (57%. Conversely none of the patients treated with intestinal derotation and colopexy died. In the subocclusive group mortality was 35% and it increased up to 50% in those patients with a late diagnosis who underwent a sigmoid resection. Conclusions The mortality of patients affected by sigmoid volvulus is related to the disease stage, prompt surgical timing, functional status of the patient and his collaboration with the clinicians in the pre-operative decision making process. Mortality is higher in both obstructed patients with generalized peritonitis and patients affected by subocclusion with late diagnosis and surgical treatment; in both scenarios a Hartmann's procedure is the proper operation to be considered.
Delay in surgical treatment of patients with hilar cholangiocarcinoma: does time impact outcomes?
Ruys, Anthony T; Heuts, Simon G; Rauws, Eric A; Busch, Olivier R C; Gouma, Dirk J; Gulik, Thomas M
2014-01-01
Background Substantial time elapses before patients with hilar cholangiocarcinoma (HCC) receive surgical treatment because of time-consuming preoperative staging and other interventions, including biliary drainage and portal vein embolization. Prolonged times potentially lead to unresectability and the formation of metastases, yet these issues have not been investigated previously in HCC. This study aimed to evaluate the time between onset of symptoms and the provision of ultimate treatment in patients with HCC and the impact of the length of time on outcomes. Methods Delays in the treatment of consecutive patients with HCC were evaluated by contacting general practitioners (GPs) and extracting data from hospital files. Time periods were correlated with resectability, occurrence of metastasis, tumour stage and survival using logistic and Cox regression analyses. Results Treatment times in 209 consecutive HCC patients were evaluated. The median time from first GP visit until presentation at the tertiary centre was 35 days. Time until treatment was longer when initial symptoms did not include jaundice (non-specific symptoms, P < 0.001). Duration of workup and preoperative biliary drainage at the tertiary centre prior to final surgical treatment resulted in an additional median time of 74 days. No correlation was found between treatment time in weeks and resectability [odds ratio (OR) 1.010, 95% confidence interval (CI) 0.985–1.036], metastasis (OR = 0.947, 95% CI 0.897–1.000), tumour stage (OR = 1.006, 95% CI 0.981–1.031) or survival in resected patients (hazard ratio = 0.996, 95% CI 0.975–1.018). Conclusions The time that elapses between the presentation of symptoms and final treatment in patients with HCC is substantial, especially in patients with non-specific symptoms. This time, however, does not affect resectability, metastasis, tumour stage or survival, which suggests that preoperative optimization should not be omitted because of potential delays in
Evaluation of Time-Dependent Behavior of Soils
DEFF Research Database (Denmark)
Augustesen, Anders; Liingaard, Morten; Lade, Poul V.
2004-01-01
The time-dependent behavior of soils has been investigated extensively through one-dimensional and triaxial test conditions. Most of the observations in literature have focused on the determination of the time-dependent behavior of clayey soils, whereas the reported experimental studies of granul...
One Dimensional Time-Dependent Tunnelling of Excitons
Kilcullen, Patrick; Salayka-Ladouceur, Logan; Malmgren, Kevin; Reid, Matthew; Shegelski, Mark R. A.
2017-03-01
We study the time-dependent tunnelling of excitons in one dimension using numerical integration based on the Crank-Nicholson method. A complete development of the time-dependent simulator is provided. External barriers studied include single and double delta barriers. We find that the appearance of transmission resonances depends strongly on the dielectric constant, relative effective masses, and initial spatial spread of the wavefunction. A discussion regarding applications to realistic systems is provided.
Real-time Near-infrared Virtual Intraoperative Surgical Photoacoustic Microscopy
Directory of Open Access Journals (Sweden)
Changho Lee
2015-09-01
Full Text Available We developed a near infrared (NIR virtual intraoperative surgical photoacoustic microscopy (NIR-VISPAM system that combines a conventional surgical microscope and an NIR light photoacoustic microscopy (PAM system. NIR-VISPAM can simultaneously visualize PA B-scan images at a maximum display rate of 45 Hz and display enlarged microscopic images on a surgeon's view plane through the ocular lenses of the surgical microscope as augmented reality. The use of the invisible NIR light eliminated the disturbance to the surgeon's vision caused by the visible PAM excitation laser in a previous report. Further, the maximum permissible laser pulse energy at this wavelength is approximately 5 times more than that at the visible spectral range. The use of a needle-type ultrasound transducer without any water bath for acoustic coupling can enhance convenience in an intraoperative environment. We successfully guided needle and injected carbon particles in biological tissues ex vivo and in melanoma-bearing mice in vivo.
The Impact of Surgical Timing in Acute Traumatic Spinal Cord Injury
2014-10-01
quality of life) in patients with a traumatic SCI. For the first reporting period, we have completed recruitment of traumatic spinal cord injured ...the major goals were to complete recruitment of our sample of 136 traumatic spinal cord injured ...TYPE Annual 3. DATES COVERED 30 Sep 2013 – 29 Sep 2014 4. TITLE AND SUBTITLE The impact of surgical timing in acute traumatic spinal cord
Real-time localization of articulated surgical instruments in retinal microsurgery.
Rieke, Nicola; Tan, David Joseph; Amat di San Filippo, Chiara; Tombari, Federico; Alsheakhali, Mohamed; Belagiannis, Vasileios; Eslami, Abouzar; Navab, Nassir
2016-12-01
Real-time visual tracking of a surgical instrument holds great potential for improving the outcome of retinal microsurgery by enabling new possibilities for computer-aided techniques such as augmented reality and automatic assessment of instrument manipulation. Due to high magnification and illumination variations, retinal microsurgery images usually entail a high level of noise and appearance changes. As a result, real-time tracking of the surgical instrument remains challenging in in-vivo sequences. To overcome these problems, we present a method that builds on random forests and addresses the task by modelling the instrument as an articulated object. A multi-template tracker reduces the region of interest to a rectangular area around the instrument tip by relating the movement of the instrument to the induced changes on the image intensities. Within this bounding box, a gradient-based pose estimation infers the location of the instrument parts from image features. In this way, the algorithm does not only provide the location of instrument, but also the positions of the tool tips in real-time. Various experiments on a novel dataset comprising 18 in-vivo retinal microsurgery sequences demonstrate the robustness and generalizability of our method. The comparison on two publicly available datasets indicates that the algorithm can outperform current state-of-the art. Copyright © 2016. Published by Elsevier B.V.
Quantum mechanics in strong time dependent external fields
Energy Technology Data Exchange (ETDEWEB)
Pomeau, Y.
1986-01-01
In quantum mechanics, time dependent Hamiltonians are most often studied by perturbation methods, the amplitude of the unsteady force being assumed to be small. On two examples (two level system with a large time dependent coupling, and atoms in large external unsteady field). I show that the opposite limit (large time dependent field) can be analyzed in some details too. For a particle in a central potential and submitted to a large periodic external field, one is led to make a Kapitza averaging because the intrinsic frequency tends to zero when the external field diverges. In that way one has to introduce a steady effective potential with singular turning points.
Jet-Ricci Geometry of Time-Dependent Human Biomechanics
Ivancevic, Tijana T
2009-01-01
We propose the time-dependent generalization of an `ordinary' autonomous human biomechanics, in which total mechanical + biochemical energy is not conserved. We introduce a general framework for time-dependent biomechanics in terms of jet manifolds derived from the extended musculo-skeletal configuration manifold. The corresponding Riemannian geometrical evolution follows the Ricci flow diffusion. In particular, we show that the exponential-like decay of total biomechanical energy (due to exhaustion of biochemical resources) is closely related to the Ricci flow on the biomechanical configuration manifold. Keywords: Time-dependent biomechanics, extended configuration manifold, configuration bundle, jet manifolds, Ricci flow diffusion
Wang, Rong; Cheng, Nan; Xiao, Cang-Song; Wu, Yang; Sai, Xiao-Yong; Gong, Zhi-Yun; Wang, Yao; Gao, Chang-Qing
2017-01-01
Background: The optimal timing of surgical revascularization for patients presenting with ST-segment elevation myocardial infarction (STEMI) and impaired left ventricular function is not well established. This study aimed to examine the timing of surgical revascularization after STEMI in patients with ischemic heart disease and left ventricular dysfunction (LVD) by comparing early and late results. Methods: From January 2003 to December 2013, there were 2276 patients undergoing isolated coronary artery bypass grafting (CABG) in our institution. Two hundred and sixty-four (223 male, 41 females) patients with a history of STEMI and LVD were divided into early revascularization (ER, 3 months) groups according to the time interval from STEMI to CABG. Mortality and complication rates were compared among the groups by Fisher's exact test. Cox regression analyses were performed to examine the effect of the time interval of surgery on long-term survival. Results: No significant differences in 30-day mortality, long-term survival, freedom from all-cause death, and rehospitalization for heart failure existed among the groups (P > 0.05). More patients in the ER group (12.90%) had low cardiac output syndrome than those in the MR (2.89%) and LR (3.05%) groups (P = 0.035). The mean follow-up times were 46.72 ± 30.65, 48.70 ± 32.74, and 43.75 ± 32.43 months, respectively (P = 0.716). Cox regression analyses showed a severe preoperative condition (odds ratio = 7.13, 95% confidence interval 2.05–24.74, P = 0.002) rather than the time interval of CABG (P > 0.05) after myocardial infarction was a risk factor of long-term survival. Conclusions: Surgical revascularization for patients with STEMI and LVD can be performed at different times after STEMI with comparable operative mortality and long-term survival. However, ER (cardiac output syndrome. A severe preoperative condition rather than the time interval of CABG after STEMI is a risk factor of long-term survival. PMID:28218210
The vehicle routing problem with time windows and temporal dependencies
DEFF Research Database (Denmark)
Dohn, Anders Høeg; Rasmussen, Matias Sevel; Larsen, Jesper
2011-01-01
In this article, we formulate the vehicle routing problem with time windows and temporal dependencies. The problem is an extension of the well studied vehicle routing problem with time windows. In addition to the usual constraints, a scheduled time of one visit may restrain the scheduling options...
Relativistic calculations of angular dependent photoemission time delay
Kheifets, A S; Deshmukh, P C; Dolmatov, V K; Manson, S T
2016-01-01
Angular dependence of photoemission time delay for the valence $np_{3/2}$ and $np_{1/2}$ subshells of Ar, Kr and Xe is studied in the dipole relativistic random phase approximation. Strong angular anisotropy of the time delay is reproduced near respective Cooper minima while the spin-orbit splitting affects the time delay near threshold.
Relativistic calculations of angle-dependent photoemission time delay
Kheifets, Anatoli; Mandal, Ankur; Deshmukh, Pranawa C.; Dolmatov, Valeriy K.; Keating, David A.; Manson, Steven T.
2016-07-01
Angular dependence of photoemission time delay for the valence n p3 /2 and n p1 /2 subshells of Ar, Kr, and Xe is studied in the dipole relativistic random phase approximation. Strong angular anisotropy of the time delay is reproduced near respective Cooper minima while the spin-orbit splitting affects the time delay near threshold.
Socioeconomic status influences time to surgery and surgical outcome in pediatric epilepsy surgery.
Rubinger, Luc; Chan, Carol; Andrade, Danielle; Go, Cristina; Smith, Mary Lou; Snead, O Carter; Rutka, James T; Widjaja, Elysa
2016-02-01
The aims of this study were to evaluate the influence of socioeconomic status (SES) on time-to-surgery (TTS) and surgical outcome in children with treatment-resistant epilepsy in a universal health care system. The cohort consisted of children who had undergone resective epilepsy surgery between 2001 and 2013 in Canada. The patients' postal codes were linked to Statistics Canada National Household Survey data to obtain dissemination area income, which was used to infer SES. Time-to-surgery was defined as the interval from date of epilepsy onset to date of surgery. Seizure outcome was classified using ILAE classification. The associations between SES and TTS, as well as SES and surgical outcome, were assessed. Two hundred eighty-four children who had epilepsy surgery were included. Patients in the lowest income quintile had a significantly higher TTS relative to the highest income quintile (β=0.121, p=0.044). There were no significant associations between income quintiles and seizure-free surgical outcome (odds ratio (OR)=0.746-1.494, all p>0.05). However, patients in the lowest income quintile had a significantly lower odds of an improvement in seizure frequency relative to the highest income quintile (OR=0.262, p=0.046). The TTS was not uniform across SES in spite of the existence of a universal health care system. This finding highlights the need to address social and economic barriers for epilepsy surgery to improve access to this potentially curative treatment. Those with lower SES had lower likelihood of improvement in seizure control following epilepsy surgery and may require additional support including social and financial support to mitigate the discrepancies in seizure control following surgery between SES levels.
Angular dependence of Wigner time delay: Relativistic Effects
Mandal, A.; Deshmukh, P. C.; Manson, S. T.; Kkeifets, A. S.
2016-05-01
Laser assisted photoionization time delay mainly consists of two parts: Wigner time delay, and time delay in continuum-continuum transition. Wigner time delay results from the energy derivative of the phase of the photoionization amplitude (matrix element). In general, the photoionization time delay is not the same in all directions relative to the incident photon polarization, although when a single transition dominates the amplitude, the resultant time delay is essentially isotropic. The relativistic-random-phase approximation is employed to determine the Wigner time delay in photoionization from the outer np subshells of the noble gas atoms, Ne through Xe. The time delay is found to significantly depend on angle, as well as energy. The angular dependence of the time delay is found to be quite sensitive to atomic dynamics and relativistic effects, and exhibit strong energy and angular variation in the neighborhood of Cooper minima. Work supported by DOE, Office of Chemical Sciences and DST (India).
Time-Dependent Behaviors of Granite: Loading-Rate Dependence, Creep, and Relaxation
Hashiba, K.; Fukui, K.
2016-07-01
To assess the long-term stability of underground structures, it is important to understand the time-dependent behaviors of rocks, such as their loading-rate dependence, creep, and relaxation. However, there have been fewer studies on crystalline rocks than on tuff, mudstone, and rock salt, because the high strength of crystalline rocks makes the detection of their time-dependent behaviors much more difficult. Moreover, studies on the relaxation, temporal change of stress and strain (TCSS) conditions, and relations between various time-dependent behaviors are scarce for not only granites, but also other rocks. In this study, previous reports on the time-dependent behaviors of granites were reviewed and various laboratory tests were conducted using Toki granite. These tests included an alternating-loading-rate test, creep test, relaxation test, and TCSS test. The results showed that the degree of time dependence of Toki granite is similar to other granites, and that the TCSS resembles the stress-relaxation curve and creep-strain curve. A viscoelastic constitutive model, proposed in a previous study, was modified to investigate the relations between the time-dependent behaviors in the pre- and post-peak regions. The modified model reproduced the stress-strain curve, creep, relaxation, and the results of the TCSS test. Based on a comparison of the results of the laboratory tests and numerical simulations, close relations between the time-dependent behaviors were revealed quantitatively.
Time dependent two phase flows in Magnetohydrodynamics: A ...
African Journals Online (AJOL)
Journal of the Nigerian Association of Mathematical Physics ... Open Access DOWNLOAD FULL TEXT Subscription or Fee Access. Time dependent two phase flows in Magnetohydrodynamics: A Greens function approach. BK Jha, HM Jibril ...
Time-dependent rheological behaviour of bacterial cellulose hydrogel.
Gao, Xing; Shi, Zhijun; Kuśmierczyk, Piotr; Liu, Changqing; Yang, Guang; Sevostianov, Igor; Silberschmidt, Vadim V
2016-01-01
This work focuses on time-dependent rheological behaviour of bacterial cellulose (BC) hydrogel. Due to its ideal biocompatibility, BC hydrogel could be employed in biomedical applications. Considering the complexity of loading conditions in human body environment, time-dependent behaviour under relevant conditions should be understood. BC specimens are produced by Gluconacetobacter xylinus ATCC 53582 at static-culture conditions. Time-dependent behaviour of specimens at several stress levels is experimentally determined by uniaxial tensile creep tests. We use fraction-exponential operators to model the rheological behaviour. Such a representation allows combination of good accuracy in analytical description of viscoelastic behaviour of real materials and simplicity in solving boundary value problems. The obtained material parameters allow us to identify time-dependent behaviour of BC hydrogel at high stress level with sufficient accuracy.
Entanglement Entropy for time dependent two dimensional holographic superconductor
Mazhari, N S; Myrzakulov, Kairat; Myrzakulov, R
2016-01-01
We studied entanglement entropy for a time dependent two dimensional holographic superconductor. We showed that the conserved charge of the system plays the role of the critical parameter to have condensation.
Skinner-Rusk approach to time-dependent mechanics
Cortés, Jorge; Martínez, Sonia; Cantrijn, Frans
2002-01-01
The geometric approach to autonomous classical mechanical systems in terms of a canonical first-order system on the Whitney sum of the tangent and cotangent bundle, developed by Skinner and Rusk, is extended to the time-dependent framework.
Time-Dependent Modulation of Cosmic Rays in the Heliosphere
Manuel, Rex; Potgieter, Marius
2013-01-01
The time-dependent modulation of galactic cosmic rays in the heliosphere is studied by computing intensities using a time-dependent modulation model. By introducing recent theoretical advances in the transport coefficients in the model, computed intensities are compared with Voyager 1, International Monitoring Platform (IMP) 8, and Ulysses proton observations in search of compatibility. The effect of different modulation parameters on computed intensities is also illustrated. It is shown that this approach produces, on a global scale, realistic cosmic-ray proton intensities along the Voyager 1 spacecraft trajectory and at Earth upto ~2004, whereafter the computed intensities recovers much slower towards solar minimum than observed in the inner heliosphere. A modified time dependence in the diffusion coefficients is proposed to improve compatibility with the observations at Earth after ~2004. This modified time dependence led to an improved compatibility between computed intensities and the observations along ...
Kinect based real-time position calibration for nasal endoscopic surgical navigation system
Fan, Jingfan; Yang, Jian; Chu, Yakui; Ma, Shaodong; Wang, Yongtian
2016-03-01
Unanticipated, reactive motion of the patient during skull based tumor resective surgery is the source of the consequence that the nasal endoscopic tracking system is compelled to be recalibrated. To accommodate the calibration process with patient's movement, this paper developed a Kinect based Real-time positional calibration method for nasal endoscopic surgical navigation system. In this method, a Kinect scanner was employed as the acquisition part of the point cloud volumetric reconstruction of the patient's head during surgery. Then, a convex hull based registration algorithm aligned the real-time image of the patient head with a model built upon the CT scans performed in the preoperative preparation to dynamically calibrate the tracking system if a movement was detected. Experimental results confirmed the robustness of the proposed method, presenting a total tracking error within 1 mm under the circumstance of relatively violent motions. These results point out the tracking accuracy can be retained stably and the potential to expedite the calibration of the tracking system against strong interfering conditions, demonstrating high suitability for a wide range of surgical applications.
Jet-Ricci Geometry of Time-Dependent Human Biomechanics
Ivancevic, Tijana T.
2009-01-01
We propose the time-dependent generalization of an `ordinary' autonomous human biomechanics, in which total mechanical + biochemical energy is not conserved. We introduce a general framework for time-dependent biomechanics in terms of jet manifolds derived from the extended musculo-skeletal configuration manifold. The corresponding Riemannian geometrical evolution follows the Ricci flow diffusion. In particular, we show that the exponential-like decay of total biomechanical energy (due to exh...
Zheng, Xiao; Yam, ChiYung; Wang, Fan; Chen, GuanHua
2011-08-28
We present the time-dependent holographic electron density theorem (TD-HEDT), which lays the foundation of time-dependent density-functional theory (TDDFT) for open electronic systems. For any finite electronic system, the TD-HEDT formally establishes a one-to-one correspondence between the electron density inside any finite subsystem and the time-dependent external potential. As a result, any electronic property of an open system in principle can be determined uniquely by the electron density function inside the open region. Implications of the TD-HEDT on the practicality of TDDFT are also discussed.
The surgical waiting time initiative: A review of the Nigerian situation
Directory of Open Access Journals (Sweden)
Imran Haruna Abdulkareem
2014-01-01
Full Text Available The concept of surgical waiting time initiative (SWAT was introduced in developed countries to reduce elective surgery waiting lists and increase efficiency of care. It was supplemented by increasing popularity of day surgery, which shortens elective waiting lists and minimises cancellations. It is established in Western countries, but not in developing countries like Nigeria where it is still evolving. A search was carried out in Pub Med, Google, African journals online (AJOL, Athens and Ovid for relevant publications on elective surgery waiting list in Nigeria, published in English language. Words include waiting/wait time, waiting time initiative, time to surgery, waiting for operations, waiting for intervention, waiting for procedures and time before surgery in Nigeria. A total of 37 articles published from Nigeria in relation to various waiting times were found from the search and fulfilled the inclusion criteria. Among them, 11 publications (29.7% were related to emergency surgery waiting times, 10 (27% were related to clinic waiting times, 9 (24.3% were related to day case surgery, 2 (5.5% were related to investigation waiting times and only 5 (13.5% articles were specifically published on elective surgery waiting times. A total of 9 articles (24.5% were published from obstetrics and gynaecology (OG, 7 (19% from general surgery, 5 (13.5% from public health, 3 (8% from orthopaedics, 3 (8% from general practice (GP, 3 (8% from paediatrics/paediatric surgery, 2 (5.5% from ophthalmology, 1 (2.7% from ear, nose and throat (ENT, 1 (2.7% from plastic surgery, 1 (2.7% from urology and only 1 (2.7% article was published from dental/maxillofacial surgery. Waiting times mean different things to different health practitioners in Nigeria. There were only 5/37 articles (13.5% specifically related to elective surgery waiting times in Nigerian hospitals, which show that the concept of the SWAT is still evolving in Nigeria. Of the 37, 11 (24
Evaluation of Time-Dependent Behavior of Soils
DEFF Research Database (Denmark)
Augustesen, Anders; Liingaard, Morten; Lade, Poul V.
2004-01-01
materials are few. This paper presents an up-to-date review of the various observed time- and rate-dependent phenomena that are known to exist for both clay and sand. The description is carried out separately for creep, stress relaxation, rate dependency, and structuration in laboratory experiments. All...... of the above-mentioned phenomena are present in both sand and clay. The time-dependent phenomena are more pronounced in clay than sand. However, sand exhibits relatively large deformations at high confining pressures because of grain crushing. Furthermore, the review revealed an essential characteristic...
Directory of Open Access Journals (Sweden)
Christophe P. M. Jayle
2015-01-01
Full Text Available Objectives. Conservative management of patients with flail chest is the treatment of choice. Rib fracture repair is technically challenging; however, with the advent of specially designed molding titanium clips, surgical management has been simplified. Surgical stabilization has been used with good outcomes. We are reporting on our institutional matched-case-control study. Methods. Between April 2010 and April 2011, ten polytraumatized patients undergoing rib stabilization for flail chest were matched 1 : 1 to 10 control patients by age ±10 years, sex, neurological or vertebral trauma, abdominal injury, and arm and leg fractures. Surgery was realized in the first 48 hours. Results. There were no significant differences between groups for matched data and prognostic scores: injury severity score, revised trauma score, and trauma injury severity score. Ventilator time (142 ± 224 versus 74 ± 125 hours, P=0.026 and overall hospital stay (142 ± 224 versus 74 ± 125 hours, P=0.026 were significantly lower for the surgical group after adjustment on prognostic scores. There was a trend towards shorter ICU stay for operative patients (12.3 ± 8.5 versus 9.0 ± 4.3 days, P=0.076. Conclusions. Rib fixation with Stracos is feasible and decreases the length of ventilation and hospital stay. A multicenter randomized study is warranted so as to confirm these results and to evaluate impact on pulmonary function status, pain, and quality of life.
Perception of night-time sleep by surgical patients in an intensive care unit.
Nicolás, Ana; Aizpitarte, Eva; Iruarrizaga, Angélica; Vázquez, Mónica; Margall, Angeles; Asiain, Carmen
2008-01-01
The night-time sleep of patients hospitalized in intensive care is a very important feature within the health or disease process, as it has a direct repercussion on their adequate recovery. (1) To describe how surgical patients perceive their sleep in the intensive care unit; (2) to compare the subjective perception of patients with the nursing records and analyse these for the degree of agreement. Descriptive research. One hundred and four surgical patients were recruited to the study. Patients completed the Richards-Campbell Sleep Questionnaire, a five-item visual analogue scale, to subjectively measure their perceived level of sleep (range 0-100 mm). The observation of patient sleep by nurses, demographic data, nursing care during the night and use of specific pharmacological treatments were also collected from the nursing records. The total mean score of sleep on the first post-operative night was 51.42 mm, 28% of patients had a good sleep, 46% a regular sleep and 26% a bad sleep. The sleep profile of these patients has been characterized by the patients having a light sleep, with frequent awakening and generally little difficulty to go back to sleep after the awakenings. The agreement between the nurses' perceptions of patients' sleep and the patients' perception of their sleep was tested by means of one-factor analysis of variance (p nurse-patient perception, we obtained 44% of total agreement and 56% of disagreement. When discrepancy was found, the nurse generally overestimated the patients' perception. Surgical patients' perceptions of their sleep in the ICU suggest that this is inadequate. Nurses' perceptions of patients' sleep partially coincides with the latter's perception, but we have also found that the former frequently overestimate patients' sleep.
Directory of Open Access Journals (Sweden)
Mehmet Ragıp Ekmen
2013-12-01
Full Text Available Purpose: Evaluation of inferior oblique muscle overaction (IOOA existence time and surgical outcomes in infantile esotropia. Material and Method: A total of 100 patients who underwent operation for infantile esotropia (IE were included in the study. Full ophthalmic assessment, including ocular motility, best-corrected visual acuity, cycloplegic refraction, any of alternant prism cover test or Hirschberg/Krimsky test, was performed. Results: Forty-nine patients (49% were male and (51% were female. The mean age at IE diagnosis was 23.2±18.6 months. The mean follow-up time was 43.7±18.0 months. The mean horizontal deviation - corrected and uncorrected - was 36.75±10.45 PD and 40.05±8.39 PD, respectively. We found that there was no statistically significant relationship between existence time of IOOA and the age at IE diagnosis (p: 0.486, p: 0.251. IOOA was detected in 69 patients. Inferior oblique (IO muscle weakening procedures were performed in 45 of 69 patients. In 45 patients who had undergone surgery for IOOA, 24 (53.3% had bilateral IO recession, 10 (22.2% had bilateral IO tenotomy, 8 (17.7% had unilateral IO tenotomy, 1(2.2% had unilateral myectomy, 1 (2.2% had bilateral myectomy, and 1 (2.2% had bilateral anteroposition. IOOA degrees after IO recession and tenotomy surgery were found to be significantly lower than the preoperative values (p=0.0586, p=0.7258. Discussion: There was no statistically significant relationship between the existence time of IOOA and the age of IE diagnosis. We concluded that IO tenotomy and IO recession surgical techniques are effective and safe procedures for cases which have IOOA associated with IE. (Turk J Ophthalmol 2013; 43: 419-23
Directory of Open Access Journals (Sweden)
Kishimoto,Fumiko
2012-06-01
Full Text Available The utility value was compared among 3 surgical interventions, and the validity of the time trade-off (TTO method was evaluated by analyzing the correlations of the utility value with the results of the Visual Function Questionnaire-14 (VF-14 and other variables. The subjects were 127 patients aged 40-85 years who were surgically treated between January 2008 and March 2010, including 26 patients with glaucoma, 50 with cataracts, and 51 with comitant strabismus. The scores on VF-14 and utility values determined using TTO were calculated retrospectively. The mean value (SD of the utility gain was 0.096 (0.105 for glaucoma, 0.101 (0.105 for comitant strabismus, and 0.167 (0.237 for unilateral and 0.245 (0.167 for bilateral cataracts, indicating significant postoperative improvements in the utility value. A significant correlation was observed between the utility value and the postoperative VF-14 scores of the bilateral cataracts, and the postoperative visual acuity of the better eye of the unilateral cataract. The mean value of the quality-adjusted life years was 2.181 for bilateral and 1.424 for unilateral cataracts, 1.132 for strabismus, and 0.870 for glaucoma with an annual discount rate of 3%. The gain of utility value was highest in bilateral cataracts, and lowest in glaucoma, and thus the TTO analysis was considered to be highly valid for cataract surgery.
The influence of timing of knee recurvatum on surgical outcome in cerebral palsy.
Klotz, Matthias C M; Heitzmann, Daniel W W; Wolf, Sebastian I; Niklasch, Mirjam; Maier, Michael W; Dreher, Thomas
2016-01-01
Recent reports have shown that timing of genu recurvatum (GR) might be caused by different underlying factors and that equinus leads to GR especially during early stance. The purpose of this study was to investigate the reduction of GR after surgical correction of equinus in children with bilateral spastic cerebral palsy and whether the children with early and late type GR show differences in reduction of knee hyperextension after a surgery. In 24 limbs (mean age 10.3 years, GMFCS I-III) showing equinus and GR the kinematics of the knee and ankle as well as the kinetics of the knee were evaluated before and one year (mean follow up period: 12.8 months) after surgical correction of equinus. The study was approved by the local ethical committee. Limbs with early type GR showed a reduction by 11.1° (pearly type GR showed increased external extending moments, which decreased significantly after surgery. In contrast limbs with late GR did not show a significant reduction of those moments. The findings of this study underline the influence of equinus on early GR as an underlying factor. As equinus is attributed to early knee hyperextension and proximal factors are more important as underlying factors in late type GR, a classification into early and late onset GR is useful to identify underlying factors and to choose adequate treatment. Copyright © 2015. Published by Elsevier Ltd.
[Abdominal artery aneurysm and associated surgical abdominal diseases: towards optimal timing].
Stilo, Francesco; Mirenda, Francesco; Mandolfino, Tommaso; La Spada, Michele; D'Alfonso, Mario; Carmignani, Amedeo; De Caridi, Giovanni; Benedetto, Filippo; Spinelli, Francesco
2003-01-01
The purpose of this study was to assess which modalities offered the best timing in the treatment of abdominal aortic aneurysms associated with other abdominal surgical diseases. From January 1984 to December 2002, 372 patients underwent surgery for abdominal aortic aneurysms, 350 men (94%) and 22 women (6%), mean age 72 years. Of these 10% were operated on urgently. The traditional open technique was used in 307 patients, and the endovascular method in the remaining 65 cases. In 40 patients (11%) we observed other associated abdominal diseases which were treated during the same operation in 34 cases (85%). We had three deaths in the 34 cases treated in the same operation (9%). In the remaining cases no perioperative mortality was registered. There were no cases of prosthesis infection. The mean hospital stay was 9 days. Simultaneous treatment appears, on the one hand, to carry an increased operative risk and increased mortality and, on the other, to present the advantage of having to perform only one surgical procedure. The advent of the endovascular method allows us to postpone the treatment of the associated disease without increasing the technical difficulty of the second operation.
A 3D radiative transfer framework. IX. Time dependence
Jack, D.; Hauschildt, P. H.; Baron, E.
2012-10-01
Context. Time-dependent, 3D radiation transfer calculations are important for the modeling of a variety of objects, from supernovae and novae to simulations of stellar variability and activity. Furthermore, time-dependent calculations can be used to obtain a 3D radiative equilibrium model structure via relaxation in time. Aims: We extend our 3D radiative transfer framework to include direct time dependence of the radiation field; i.e., the ∂I/∂t terms are fully considered in the solution of radiative transfer problems. Methods: We build on the framework that we have described in previous papers in this series and develop a subvoxel method for the ∂I/∂t terms. Results: We test the implementation by comparing the 3D results to our well tested 1D time dependent radiative transfer code in spherical symmetry. A simple 3D test model is also presented. Conclusions: The 3D time dependent radiative transfer method is now included in our 3D RT framework and in PHOENIX/3D.
A 3D radiative transfer framework IX. Time dependence
Jack, D; Baron, E
2012-01-01
Context. Time-dependent, 3D radiation transfer calculations are important for the modeling of a variety of objects, from supernovae and novae to simulations of stellar variability and activity. Furthermore, time-dependent calculations can be used to obtain a 3D radiative equilibrium model structure via relaxation in time. Aims. We extend our 3D radiative transfer framework to include direct time dependence of the radiation field; i.e., the $\\partial I/ \\partial t$ terms are fully considered in the solution of radiative transfer problems. Methods. We build on the framework that we have described in previous papers in this series and develop a subvoxel method for the $\\partial I/\\partial t$ terms. Results. We test the implementation by comparing the 3D results to our well tested 1D time dependent radiative transfer code in spherical symmetry. A simple 3D test model is also presented. Conclusions. The 3D time dependent radiative transfer method is now included in our 3D RT framework and in PHOENIX/3D.
PRODUCT FORMULA METHODS FOR TIME-DEPENDENT SCHRODINGER PROBLEMS
HUYGHEBAERT, J; DERAEDT, H
1990-01-01
This paper introduces a family of explicit and unconditionally stable algorithms for solving linear differential equations which contain a time-dependent Hermitian operator. Rigorous upper bounds are derived for two different `time-ordered' approximation schemes and for errors resulting from approxi
Characterization of Models for Time-Dependent Behavior of Soils
DEFF Research Database (Denmark)
Liingaard, Morten; Augustesen, Anders; Lade, Poul V.
2004-01-01
Different classes of constitutive models have been developed to capture the time-dependent viscous phenomena ~ creep, stress relaxation, and rate effects ! observed in soils. Models based on empirical, rheological, and general stress-strain-time concepts have been studied. The first part is a r...
Time dependent analysis with dynamic counter measure trees
Kumar, Rajesh; Guck, Dennis; Stoelinga, Mariëlle Ida Antoinette
2015-01-01
The success of a security attack crucially depends on time: the more time available to the attacker, the higher the probability of a successful attack. Formalisms such as Reliability block diagrams, Reliability graphs and Attack Countermeasure trees provide quantitative information about attack scen
Student Understanding of Time Dependence in Quantum Mechanics
Emigh, Paul J.; Passante, Gina; Shaffer, Peter S.
2015-01-01
The time evolution of quantum states is arguably one of the more difficult ideas in quantum mechanics. In this article, we report on results from an investigation of student understanding of this topic after lecture instruction. We demonstrate specific problems that students have in applying time dependence to quantum systems and in recognizing…
Student Understanding of Time Dependence in Quantum Mechanics
Emigh, Paul J.; Passante, Gina; Shaffer, Peter S.
2015-01-01
The time evolution of quantum states is arguably one of the more difficult ideas in quantum mechanics. In this article, we report on results from an investigation of student understanding of this topic after lecture instruction. We demonstrate specific problems that students have in applying time dependence to quantum systems and in recognizing…
Branch and price for the time-dependent vehicle routing problem with time windows
DEFF Research Database (Denmark)
Dabia, Said; Van Woensel, Tom; De Kok, Ton
2013-01-01
solution methods to the DM-TDVRPTW are based on (meta-)heuristics. The decomposition of an arc-based formulation leads to a setpartitioning problem as the master problem, and a time-dependent shortest path problem with resource constraints as the pricing problem. The master problem is solved by means...... of column generation, and a tailored labeling algorithm is used to solve the pricing problem. We introduce new dominance criteria that allow more label dominance. For our numerical results, we modified Solomon's data sets by adding time dependency. Our algorithm is able to solve about 63% of the instances......This paper presents a branch-and-price algorithm for the time-dependent vehicle routing problem with time windows (TDVRPTW). We capture road congestion by considering time-dependent travel times, i.e., depending on the departure time to a customer, a different travel time is incurred. We consider...
Copulas and time series with long-ranged dependences
Chicheportiche, Rémy
2013-01-01
We review ideas on temporal dependences and recurrences in discrete time series from several areas of natural and social sciences. We revisit existing studies and redefine the relevant observables in the language of copulas (joint laws of the ranks). We propose that copulas provide an appropriate mathematical framework to study non-linear time dependences and related concepts - like aftershocks, Omori law, recurrences, waiting times. We also critically argue using this global approach that previous phenomenological attempts involving only a long-ranged autocorrelation function lacked complexity in that they were essentially mono-scale.
Direct imaging of small scatterers using reduced time dependent data
Cakoni, Fioralba; Rezac, Jacob D.
2017-06-01
We introduce qualitative methods for locating small objects using time dependent acoustic near field waves. These methods have reduced data collection requirements compared to typical qualitative imaging techniques. In particular, we only collect scattered field data in a small region surrounding the location from which an incident field was transmitted. The new methods are partially theoretically justified and numerical simulations demonstrate their efficacy. We show that these reduced data techniques give comparable results to methods which require full multistatic data and that these time dependent methods require less scattered field data than their time harmonic analogs.
Time-dependent massless Dirac fermions in graphene
Energy Technology Data Exchange (ETDEWEB)
Khantoul, Boubakeur, E-mail: bobphys@gmail.com [Department of Mathematics, City University London, Northampton Square, London EC1V 0HB (United Kingdom); Department of Physics, University of Jijel, BP 98, Ouled Aissa, 18000 Jijel (Algeria); Fring, Andreas, E-mail: a.fring@city.ac.uk [Department of Mathematics, City University London, Northampton Square, London EC1V 0HB (United Kingdom)
2015-10-30
Using the Lewis–Riesenfeld method of invariants we construct explicit analytical solutions for the massless Dirac equation in 2+1 dimensions describing quasi-particles in graphene. The Hamiltonian of the system considered contains some explicit time-dependence in addition to one resulting from being minimally coupled to a time-dependent vector potential. The eigenvalue equations for the two spinor components of the Lewis–Riesenfeld invariant are found to decouple into a pair of supersymmetric invariants in a similar fashion as the known decoupling for the time-independent Dirac Hamiltonians. - Highlights: • An explicit analytical solution for a massless 2+1 dimensional time-dependent Dirac equation is found. • All steps of the Lewis–Riesenfeld method have been carried out.
Eigenstates of the time-dependent density-matrix theory
Energy Technology Data Exchange (ETDEWEB)
Tohyama, M. [Kyorin University School of Medicine, 181-8611, Mitaka, Tokyo (Japan); Schuck, P. [Institut de Physique Nucleaire, IN2P3-CNRS, Universite Paris-Sud, F-91406, Orsay Cedex (France)
2004-02-01
An extended time-dependent Hartree-Fock theory, known as the time-dependent density-matrix theory (TDDM), is solved as a time-independent eigenvalue problem for low-lying 2{sup +} states in {sup 24}O to understand the foundation of the rather successful time-dependent approach. It is found that the calculated strength distribution of the 2{sup +} states has physically reasonable behavior and that the strength function is practically positive definite though the non-Hermitian Hamiltonian matrix obtained from TDDM does not guarantee it. A relation to an Extended RPA theory with hermiticity is also investigated. It is found that the density-matrix formalism is a good approximation to the Hermitian Extended RPA theory. (orig.)
Jet Methods in Time-Dependent Lagrangian Biomechanics
Ivancevic, Tijana T
2009-01-01
In this paper we propose the time-dependent generalization of an `ordinary' autonomous human biomechanics, in which total mechanical + biochemical energy is not conserved. We introduce a general framework for time-dependent biomechanics in terms of jet manifolds associated to the extended musculo-skeletal configuration manifold, called the configuration bundle. We start with an ordinary configuration manifold of human body motion, given as a set of its all active degrees of freedom (DOF) for a particular movement. This is a Riemannian manifold with a material metric tensor given by the total mass-inertia matrix of the human body segments. This is the base manifold for standard autonomous biomechanics. To make its time-dependent generalization, we need to extend it with a real time axis. By this extension, using techniques from fibre bundles, we defined the biomechanical configuration bundle. On the biomechanical bundle we define vector-fields, differential forms and affine connections, as well as the associat...
Concordance of expert and parental opinion about hypospadias surgical outcome is severity-dependent
Directory of Open Access Journals (Sweden)
Marcos Raymond Perez-Brayfield
2016-01-01
Full Text Available Introduction. Hypospadias is a male congenital condition where the opening of the urethral meatus is not located in the typical anatomical position. It has been a challenge for empirical studies to ascertain the level of concordance of opinion among parents and urologists with regard to surgical outcomes according to hypospadias severity. Materials and Methods. Parents of children who had undergone hypospadias repair were recruited for this study (n=104. A set of questionnaires that included some items with Likert scale were created to evaluate postsurgical satisfaction by parents and urologists. SAHLSA-50, a validated instrument for adult Spanish-speaking adults, was used to assess health literacy. Cohen’s Kappa (k coefficient was used to assess inter-observer agreement and Chi Square Goodness of Fit Test was used to determine probability of satisfaction. Findings. Concordance on the level of satisfaction with surgical outcomes for Type cases I was slight (k=0.20; CI 95% 0-0.60, for Type II cases was moderate (k= 0.54; CI 95% 0.13-0.94, and for Type III cases was substantial (k=0.62; CI 95% 0-0.56. However, the probability of satisfaction did not change according to severity (Chi Square Goodness of Fit Test; parents, p=0.84; pediatric urologists, p=0.92. These results cannot be explained by parental health literacy according to SAHLSA-50 test scores. Conclusions. The level of concordance of opinion among parents and urologists with regard to their level of satisfaction with surgical outcomes is related to hypospadias severity, whereby the greatest level of concordance of opinion was achieved among most severe cases. This study underscores the need for longer follow-up to properly assess satisfaction with hypospadias repair, especially for the less severe forms of the condition.
Zhang, Kang
2011-12-01
In this dissertation, real-time Fourier domain optical coherence tomography (FD-OCT) capable of multi-dimensional micrometer-resolution imaging targeted specifically for microsurgical intervention applications was developed and studied. As a part of this work several ultra-high speed real-time FD-OCT imaging and sensing systems were proposed and developed. A real-time 4D (3D+time) OCT system platform using the graphics processing unit (GPU) to accelerate OCT signal processing, the imaging reconstruction, visualization, and volume rendering was developed. Several GPU based algorithms such as non-uniform fast Fourier transform (NUFFT), numerical dispersion compensation, and multi-GPU implementation were developed to improve the impulse response, SNR roll-off and stability of the system. Full-range complex-conjugate-free FD-OCT was also implemented on the GPU architecture to achieve doubled image range and improved SNR. These technologies overcome the imaging reconstruction and visualization bottlenecks widely exist in current ultra-high speed FD-OCT systems and open the way to interventional OCT imaging for applications in guided microsurgery. A hand-held common-path optical coherence tomography (CP-OCT) distance-sensor based microsurgical tool was developed and validated. Through real-time signal processing, edge detection and feed-back control, the tool was shown to be capable of track target surface and compensate motion. The micro-incision test using a phantom was performed using a CP-OCT-sensor integrated hand-held tool, which showed an incision error less than +/-5 microns, comparing to >100 microns error by free-hand incision. The CP-OCT distance sensor has also been utilized to enhance the accuracy and safety of optical nerve stimulation. Finally, several experiments were conducted to validate the system for surgical applications. One of them involved 4D OCT guided micro-manipulation using a phantom. Multiple volume renderings of one 3D data set were
Time dependence of the pH of rain
John A. Kadlecek; Volkar A. Mohnen
1976-01-01
Standard procedures for determining the pH of rain samples usually involve substantial delays from the time of rainfall to the time of analysis. This assumes that no change in pH occurs during the storage period. We have found that this is not always true. We have determined that individual rain water samples possess a time dependent pH which can be correlated with the...
Unique Measure for Time-Dependent Random Dynamical Systems
Varner, Gregory
2016-01-01
This paper proves the uniqueness of measure for the two-dimensional Navier-Stokes equations under a random kick-force and a time-dependent deterministic force. By extending a result for uniqueness of measure for time-homogeneous Markov processes to the time-inhomogeneous case, it is shown that the measures are exponentially mixing for the 2D Navier-Stokes equations on the sphere.
Kranzfelder, Michael; Zywitza, Dorit; Jell, Thomas; Schneider, Armin; Gillen, Sonja; Friess, Helmut; Feussner, Hubertus
2012-06-15
Technical progress in the surgical operating room (OR) increases constantly, facilitating the development of intelligent OR systems functioning as "safety backup" in the background of surgery. Precondition is comprehensive data retrieval to identify imminent risky situations and inaugurate adequate security mechanisms. Radio-frequency-identification (RFID) technology may have the potential to meet these demands. We set up a pilot study investigating feasibility and appliance reliability of a stationary RFID system for real-time surgical sponge monitoring (passive tagged sponges, position monitoring: mayo-stand/abdominal situs/waste bucket) and OR team tracking (active transponders, position monitoring: right/left side of OR table). In vitro: 20/20 sponges (100%) were detected on the mayo-stand and within the OR-phantom, however, real-time detection accuracy declined to 7/20 (33%) when the tags were moved simultaneously. All retained sponges were detected correctly. In vivo (animal): 7-10/10 sterilized sponges (70%-100%) were detected correctly within the abdominal cavity. OR-team: detection accuracy within the OR (surveillance antenna) and on both sides of the OR table (sector antenna) was 100%. Mean detection time for position change (left to right side and contrariwise) was 30-60 s. No transponder failure was noted. This is the first combined RFID system that has been developed for stationary use in the surgical OR. Preclinical evaluation revealed a reliable sponge tracking and correct detection of retained textiles (passive RFID) but also demonstrated feasibility of comprehensive data acquisition of team motion (active RFID). However, detection accuracy needs to be further improved before implementation into the surgical OR. Copyright © 2012 Elsevier Inc. All rights reserved.
Insulin-dependent and insulin-independent effects after surgical alterations of the pancreas.
Krusch, D A; Brown, K B; Cornett, G; Freedlender, A E; Kaiser, D L; Hanks, J B
1989-07-01
Anatomic alterations of the pancreas result in physiologic alterations that have not been completely analyzed. Insulin plays a major role in carbohydrate metabolism; nevertheless, as much as 50% of a hyperglycemic load may be metabolized independent of insulin. We analyzed the effects of surgical alterations of the pancreas on postoperative glucose metabolism, including insulin-independent effects. Mongrel female dogs underwent one of three procedures: proximal partial pancreatectomy (PPx), PPx plus diversion of pancreatic venous effluent to the systemic circulation (SC), or PPx plus segmental pancreatic autotransplantation (PAT). Intravenous glucose tolerance tests, with or without a background infusion of somatostatin (SST; 400 ng/kg/min) were performed on all animals preoperatively and postoperatively. SST completely suppressed secretion of assayable peripheral insulin. The rate of glucose disposal during SST suppression approximates the rate of insulin-independent glucose disposal (IIGD). Although there was a significant decrease in the rate of glucose disposal during SST infusion when compared with the rate without SST, no differences in IIGD were found between postoperative groups. IIGD was calculated at 50% to 55% for control, PPx, and SC groups and at 67% for PAT. Peripheral sensitivity to an exogenous insulin infusion (euglycemic clamp) was unchanged by any of the procedures. We conclude that surgical alteration of the pancreas, including pancreas transplantation, results in altered glucose handling in the face of "normal" peripheral levels of insulin. Changes in IIGD and analysis of peripheral sensitivity to insulin do not explain these alterations completely.
Grihn, V K; Kondratenko, P G; Melekhovets, Yu V; Sinyachenko, Yu O; Sinyachenko, O V
2015-05-01
Physico-chemical adsorption-rheological properties of venous blood in patients, suffering varicose disease of the lower extremities, and their impact on efficacy of various methods of surgical treatment were studied. Conduction of endovasal laser coagulation in combination with crossectomy have promoted enhancement of operative treatment efficacy in patients in initial terms of observation (in 1 week), in 1 month a complete occlusion of the vein was noted more rarely. Efficacy of a small--power laser ablation with irradiation power of 10 W and less in 4 weeks postoperatively is higher, than of surgical treatment with a laser irradiation power 15 W. In a varicose disease of the lower extremities there were observed the raising of the blood volume toughness, superficial relaxation and superficial stress on background of reduction of the toughness--elasticity module, superficial toughness and superficial elasticity. Crossectomy conduction did not influence the integral dynamics of adsorption--rheological properties of venous blood, but in 1 month after endovasal laser coagulation a normalization of physicchemical parameters of blood was noted. Application of laser irradiation of the 10 W power and less promotes inhibition of the relaxation properties of venous blood; a prognostic meaning owes initial value of the blood volume toughness.
Rosson, Gedge D; Magarakis, Michael; Shridharani, Sachin M; Stapleton, Sahael M; Jacobs, Lisa K; Manahan, Michele A; Flores, Jaime I
2010-07-01
The oncologic management of breast cancer has evolved over the past several decades from radical mastectomy to modern-day preservation of chest and breast structures. The increased rate of mastectomies over recent years made breast reconstruction an integral part of the breast cancer management. Plastic surgery now offers patients a wide variety of reconstruction options from primary closure of the skin flaps to performance of microvascular and autologous tissue transplantation. Well-coordinated partnerships between surgical oncologists, plastic surgeons, and patients address concerns of tumor control, cosmesis, and patients' wishes. The gamut of breast reconstruction options is reviewed, particularly noting state-of-the-art techniques, as well as the advantages and disadvantages of various timing modalities.
Surgical training and the European Working Time Directive: The role of informal workplace learning.
Giles, James A
2010-01-01
The introduction of European Working Time Directive, limiting doctors' working hours to 48 per week, has caused recent controversy within the profession. The Royal College of Surgeons of England in particular has been one of the loudest critics of the legislation. One of the main concerns is regarding the negative impact on training hours for those embarking on surgical careers. Simulation technology has been suggested as a method to overcome this reduction in hospital training hours, and research suggests that this is a good substitute for operative training in a theatre. However, modern educational theory emphasises the power of informal workplace learning in postgraduate education, and the essential role of experience in training future surgeons.
Observation of detection-dependent multi-photon coherence times
DEFF Research Database (Denmark)
Ra, Young-Sik; Tichy, Malte C.; Lim, Hyang-Tag;
2013-01-01
in which the multi-photon coherence time, defined by the width of the interference signal, depends on the number of interfering photons and on the measurement scheme chosen to detect the particles. A theoretical analysis reveals that all multi-photon interferences with more than two particles feature...... this dependence, which can be attributed to higher-order effects in the mutual indistinguishability of the particles. As a striking consequence, a single, well-defined many-particle quantum state can exhibit qualitatively different degrees of interference, depending on the chosen observable. Therefore, optimal...... sensitivity in many-particle quantum interferometry can only be achieved by choosing a suitable detection scheme....
Dynamic structure evolution of time-dependent network
Zhang, Beibei; Zhou, Yadong; Xu, Xiaoyan; Wang, Dai; Guan, Xiaohong
2016-08-01
In this paper, we research the long-voided problem of formulating the time-dependent network structure evolution scheme, it focus not only on finding new emerging vertices in evolving communities and new emerging communities over the specified time range but also formulating the complex network structure evolution schematic. Previous approaches basically applied to community detection on time static networks and thus failed to consider the potentially crucial and useful information latently embedded in the dynamic structure evolution process of time-dependent network. To address these problems and to tackle the network non-scalability dilemma, we propose the dynamic hierarchical method for detecting and revealing structure evolution schematic of the time-dependent network. In practice and specificity, we propose an explicit hierarchical network evolution uncovering algorithm framework originated from and widely expanded from time-dependent and dynamic spectral optimization theory. Our method yields preferable results compared with previous approaches on a vast variety of test network data, including both real on-line networks and computer generated complex networks.
Stability on time-dependent domains: convective and dilution effects
Krechetnikov, R.; Knobloch, E.
2017-03-01
We explore near-critical behavior of spatially extended systems on time-dependent spatial domains with convective and dilution effects due to domain flow. As a paradigm, we use the Swift-Hohenberg equation, which is the simplest nonlinear model with a non-zero critical wavenumber, to study dynamic pattern formation on time-dependent domains. A universal amplitude equation governing weakly nonlinear evolution of patterns on time-dependent domains is derived and proves to be a generalization of the standard Ginzburg-Landau equation. Its key solutions identified here demonstrate a substantial variety-spatially periodic states with a time-dependent wavenumber, steady spatially non-periodic states, and pulse-train solutions-in contrast to extended systems on time-fixed domains. The effects of domain flow, such as bifurcation delay due to domain growth and destabilization due to oscillatory domain flow, on the Eckhaus instability responsible for phase slips in spatially periodic states are analyzed with the help of both local and global stability analyses. A nonlinear phase equation describing the approach to a phase-slip event is derived. Detailed analysis of a phase slip using multiple time scale methods demonstrates different mechanisms governing the wavelength changing process at different stages.
Reversible and Irreversible Time-Dependent Behavior of GRCop-84
Lerch, Bradley A.; Arnold, Steven M.; Ellis, David L.
2017-01-01
A series of mechanical tests were conducted on a high-conductivity copper alloy, GRCop-84, in order to understand the time dependent response of this material. Tensile, creep, and stress relaxation tests were performed over a wide range of temperatures, strain rates, and stress levels to excite various amounts of time-dependent behavior. At low applied stresses the deformation behavior was found to be fully reversible. Above a certain stress, termed the viscoelastic threshold, irreversible deformation was observed. At these higher stresses the deformation was observed to be viscoplastic. Both reversible and irreversible regions contained time dependent deformation. These experimental data are documented to enable characterization of constitutive models to aid in design of high temperature components.
Time-dependent stabilization in AdS/CFT
Auzzi, Roberto; Gudnason, Sven Bjarke; Rabinovici, Eliezer
2012-01-01
We consider theories with time-dependent Hamiltonians which alternate between being bounded and unbounded from below. For appropriate frequencies dynamical stabilization can occur rendering the effective potential of the system stable. We first study a free field theory on a torus with a time-dependent mass term, finding that the stability regions are described in terms of the phase diagram of the Mathieu equation. Using number theory we have found a compactification scheme such as to avoid resonances for all momentum modes in the theory. We further consider the gravity dual of a conformal field theory on a sphere in three spacetime dimensions, deformed by a doubletrace operator. The gravity dual of the theory with a constant unbounded potential develops big crunch singularities; we study when such singularities can be cured by dynamical stabilization. We numerically solve the Einstein-scalar equations of motion in the case of a time-dependent doubletrace deformation and find that for sufficiently high freque...
The Vehicle Routing Problem with Time Windows and Temporal Dependencies
DEFF Research Database (Denmark)
Rasmussen, Matias Sevel; Dohn, Anders Høeg; Larsen, Jesper
The vehicle routing problem with time windows and temporal dependencies (VRPTWTD) is an extension of the vehicle routing problem with time windows (VRPTW). Given is a fixed set of customers with individual demands and with time windows specifying when each customer accepts service. The objective...... is to find routes for a number of vehicles, all starting and ending at a central depot in such a way that the total distance is minimized. The extension that we present here is concerned with temporal dependencies between customers. A temporal dependency which is often encountered in practical instances...... assignment and routing problem with synchronization constraints. The problem has been solved by column generation. The synchronized vehicle dispatching problem (SVDP), which is a dynamic vehicle routing problem with synchronization between vehicles. Constraint programming and local search are applied...
Quadratic time dependent Hamiltonians and separation of variables
Anzaldo-Meneses, A.
2017-06-01
Time dependent quantum problems defined by quadratic Hamiltonians are solved using canonical transformations. The Green's function is obtained and a comparison with the classical Hamilton-Jacobi method leads to important geometrical insights like exterior differential systems, Monge cones and time dependent Gaussian metrics. The Wei-Norman approach is applied using unitary transformations defined in terms of generators of the associated Lie groups, here the semi-direct product of the Heisenberg group and the symplectic group. A new explicit relation for the unitary transformations is given in terms of a finite product of elementary transformations. The sequential application of adequate sets of unitary transformations leads naturally to a new separation of variables method for time dependent Hamiltonians, which is shown to be related to the Inönü-Wigner contraction of Lie groups. The new method allows also a better understanding of interacting particles or coupled modes and opens an alternative way to analyze topological phases in driven systems.
Time-dependent density functional theory for quantum transport.
Zheng, Xiao; Chen, GuanHua; Mo, Yan; Koo, SiuKong; Tian, Heng; Yam, ChiYung; Yan, YiJing
2010-09-21
Based on our earlier works [X. Zheng et al., Phys. Rev. B 75, 195127 (2007); J. S. Jin et al., J. Chem. Phys. 128, 234703 (2008)], we propose a rigorous and numerically convenient approach to simulate time-dependent quantum transport from first-principles. The proposed approach combines time-dependent density functional theory with quantum dissipation theory, and results in a useful tool for studying transient dynamics of electronic systems. Within the proposed exact theoretical framework, we construct a number of practical schemes for simulating realistic systems such as nanoscopic electronic devices. Computational cost of each scheme is analyzed, with the expected level of accuracy discussed. As a demonstration, a simulation based on the adiabatic wide-band limit approximation scheme is carried out to characterize the transient current response of a carbon nanotube based electronic device under time-dependent external voltages.
Noncommutative quantum mechanics in a time-dependent background
Dey, Sanjib; Fring, Andreas
2014-10-01
We investigate a quantum mechanical system on a noncommutative space for which the structure constant is explicitly time dependent. Any autonomous Hamiltonian on such a space acquires a time-dependent form in terms of the conventional canonical variables. We employ the Lewis-Riesenfeld method of invariants to construct explicit analytical solutions for the corresponding time-dependent Schrödinger equation. The eigenfunctions are expressed in terms of the solutions of variants of the nonlinear Ermakov-Pinney equation and discussed in detail for various types of background fields. We utilize the solutions to verify a generalized version of Heisenberg's uncertainty relations for which the lower bound becomes a time-dependent function of the background fields. We study the variance for various states, including standard Glauber coherent states with their squeezed versions and Gaussian Klauder coherent states resembling a quasiclassical behavior. No type of coherent state appears to be optimal in general with regard to achieving minimal uncertainties, as this feature turns out to be background field dependent.
[Perception of night-time sleep by the surgical patients in an intensive care unit].
Nicolás, A; Aizpitarte, E; Iruarrizaga, A; Vázquez, M; Margall, M A; Asiain, M C
2002-01-01
Night-time rest of the patients hospitalized in Intensive Care is a very important feature within the health/disease process since it has a direct repercussion on their adequate recovery. The objectives of this investigation are: 1) describe how the surgical patients perceive their night-time sleep in the Polyvalent Intensive Care Unit: 2) compare the subjective perception of the patients with the nursing record in the care plan and analyze the degree of agreement between both assessments. Night-time sleep has been studied in 104 patients; surgery patients from emergencies, patients who are intubated, with previous psychiatric treatment, sleep apnea, drinking habit or impossibility of adequate communication were not included. To measure the patient's perception, the five item sleep questionnaire of Richards-Campbell and the assessment of sleep by the nurse, as well as the remaining variables included in a computerized care plan, were used. The total mean score of the sleep on the first post-operative night was 51.42 mm. When the scores obtained in each one of the questionnaire items are analyzed, it is seen that the sleep profile of these patients has been characterized by being light sleep, with frequent wakenings and generally with little difficulty to go back to sleep when woke op or were awakened. The assessment of the night-time sleep performed by the nurse coincides with the perception of the patients on many occasions, and when there is discrepancy, the nurse has overestimated the patient's sleep.
On a definition of the appropriate timing for surgical intervention in orthognathic surgery.
Hernández-Alfaro, F; Guijarro-Martínez, R
2014-07-01
Together with the introduction of new orthodontic techniques and minimally invasive surgery protocols, the emergence of modern patient prototypes has given way to novel timing schemes for the handling of dento-maxillofacial deformities. The aim of this study was to define, justify, and systematize the appropriate timing for orthognathic surgery. A retrospective analysis of orthognathic surgery procedures carried out over a 3-year period was performed. Six timing schemes were defined: 'surgery first', 'surgery early', 'surgery late', 'surgery last', 'surgery only', and 'surgery never'. Gender, age at surgery, main motivation for treatment, orthodontic treatment length, and number of orthodontic appointments were evaluated. A total of 362 orthognathic procedures were evaluated. The most common approach was 'surgery late'. While aesthetic improvement was the leading treatment motivation in 'surgery first', 'surgery early', and 'surgery last' cases, occlusal optimization was the chief aim of 'surgery late'. Sleep-disordered breathing was the main indication for treatment in 'surgery only'. Compared to 'surgery late', orthodontic treatment was substantially shorter in 'surgery early' and 'surgery first' cases, but the number of orthodontic appointments was similar. In conclusion, the skilful management of dento-maxillofacial deformities requires a comprehensive analysis of patient-, orthodontist-, and surgeon-specific variables. Each timing approach has well-defined indications, treatment planning considerations, and orthodontic and surgical peculiarities.
Time-Dependent Collective Neutrino Oscillations in Supernovae
Abbar, Sajad; Duan, Huaiyu
2015-10-01
Neutrinos can experience self-induced flavor conversion in core-collapse supernovae due to neutrino-neutrino forward scattering. Previously a stationary supernova model, the so called ``neutrino bulb model,'' was used exclusively to study collective neutrino oscillations in the core-collapse supernova. We show that even a small time-dependent perturbation in neutrino fluxes on the surface of the proto-neutron star can lead to fast varying collective oscillations at large radii. This result calls for time-dependent supernova models for the study of collective neutrino oscillations. This work was supported by DOE EPSCoR Grant DE-SC0008142 at UNM.
Vacuum radiation induced by time dependent electric field
Directory of Open Access Journals (Sweden)
Bo Zhang
2017-04-01
Full Text Available Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.
Exact response functions within the time-dependent Gutzwiller approach
Bünemann, J.; Wasner, S.; Oelsen, E. v.; Seibold, G.
2015-02-01
We investigate the applicability of the two existing versions of a time-dependent Gutzwiller approach (TDGA) beyond the frequently used limit of infinite spatial dimensions. To this end, we study the two-particle response functions of a two-site Hubbard model where we can compare the exact results and those derived from the TDGA. It turns out that only the more recently introduced version of the TDGA can be combined with a diagrammatic approach which allows for the evaluation of Gutzwiller wave functions in finite dimensions. For this TDGA method, we derive the time-dependent Lagrangian for general single-band Hubbard models.
Time-dependent perturbation theory for inelastic scattering
Cross, R. J.
1982-08-01
We show by numerical integration that the first-order, time-dependent, Magnus approximation agrees with the first-order, exponential, distorted-wave approximation to within a few percent, provided that the trajectory used for the time-dependent calculation is characterized by the arithmetic mean of the initial and final velocities and the arithmetic mean of the initial and final orbital angular momenta. Calculations are done for rotational energy transfer from an exponentially repulsive potential characteristic of He+H2 and for a Lennard-Jones potential characteristic of Ar+N2.
Vacuum radiation induced by time dependent electric field
Zhang, Bo; Zhang, Zhi-meng; Hong, Wei; He, Shu-Kai; Teng, Jian; Gu, Yu-qiu
2017-04-01
Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED) will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.
The time-dependent prize-collecting arc routing problem
DEFF Research Database (Denmark)
Black, Dan; Eglese, Richard; Wøhlk, Sanne
2013-01-01
A new problem is introduced named the Time-Dependent Prize-Collecting Arc Routing Problem (TD-PARP). It is particularly relevant to situations where a transport manager has to choose between a number of full truck load pick-ups and deliveries on a road network where travel times change...... with the time of day. Two metaheuristic algorithms, one based on Variable Neighborhood Search and one based on Tabu Search, are proposed and tested for a set of benchmark problems, generated from real road networks and travel time information. Both algorithms are capable of finding good solutions, though...
Tokamak power reactor ignition and time dependent fractional power operation
Energy Technology Data Exchange (ETDEWEB)
Vold, E.L.; Mau, T.K.; Conn, R.W.
1986-06-01
A flexible time-dependent and zero-dimensional plasma burn code with radial profiles was developed and employed to study the fractional power operation and the thermal burn control options for an INTOR-sized tokamak reactor. The code includes alpha thermalization and a time-dependent transport loss which can be represented by any one of several currently popular scaling laws for energy confinement time. Ignition parameters were found to vary widely in density-temperature (n-T) space for the range of scaling laws examined. Critical ignition issues were found to include the extent of confinement time degradation by alpha heating, the ratio of ion to electron transport power loss, and effect of auxiliary heating on confinement. Feedback control of the auxiliary power and ion fuel sources are shown to provide thermal stability near the ignition curve.
Solvable time-dependent models in quantum mechanics
Cordero-Soto, Ricardo J.
In the traditional setting of quantum mechanics, the Hamiltonian operator does not depend on time. While some Schrodinger equations with time-dependent Hamiltonians have been solved, explicitly solvable cases are typically scarce. This thesis is a collection of papers in which this first author along with Suslov, Suazo, and Lopez, has worked on solving a series of Schrodinger equations with a time-dependent quadratic Hamiltonian that has applications in problems of quantum electrodynamics, lasers, quantum devices such as quantum dots, and external varying fields. In particular the author discusses a new completely integrable case of the time-dependent Schrodinger equation in Rn with variable coefficients for a modified oscillator, which is dual with respect to the time inversion to a model of the quantum oscillator considered by Meiler, Cordero-Soto, and Suslov. A second pair of dual Hamiltonians is found in the momentum representation. Our examples show that in mathematical physics and quantum mechanics a change in the direction of time may require a total change of the system dynamics in order to return the system back to its original quantum state. The author also considers several models of the damped oscillators in nonrelativistic quantum mechanics in a framework of a general approach to the dynamics of the time-dependent Schrodinger equation with variable quadratic Hamiltonians. The Green functions are explicitly found in terms of elementary functions and the corresponding gauge transformations are discussed. The factorization technique is applied to the case of a shifted harmonic oscillator. The time-evolution of the expectation values of the energy related operators is determined for two models of the quantum damped oscillators under consideration. The classical equations of motion for the damped oscillations are derived for the corresponding expectation values of the position operator. Finally, the author constructs integrals of motion for several models
A time-dependent measuring system for welding deformation
Institute of Scientific and Technical Information of China (English)
蔡志鹏; 赵海燕; 鹿安理; 史清宇; 施光凯
2002-01-01
In this paper the establishment and application of a time-dependent measuring system for welding deformation are presented which is established with high quality sensors shielded from strong welding interference. By using this system, vertical and horizontal displacements of the high temperature area are surveyed at the same time. And this system is also used for monitoring and controlling the deformation of real welded structures.
Time dependent density functional calculation of plasmon response in clusters
Institute of Scientific and Technical Information of China (English)
Wang Feng(王锋); Zhang Feng-Shou(张丰收); Eric Suraud
2003-01-01
We have introduced a theoretical scheme for the efficient description of the optical response of a cluster based on the time-dependent density functional theory. The practical implementation is done by means of the fully fledged timedependent local density approximation scheme, which is solved directly in the time domain without any linearization.As an example we consider the simple Na2 cluster and compute its surface plasmon photoabsorption cross section, which is in good agreement with the experiments.
Dirac equation on coordinate dependent noncommutative space–time
Kupriyanov, V. G.
2014-01-01
We consider the consistent deformation of the relativistic quantum mechanics introducing the noncommutativity of the space-time and preserving the Lorentz symmetry. The relativistic wave equation describing the spinning particle on coordinate dependent noncommutative space-time (noncommutative Dirac equation) is proposed. The fundamental properties of this equation, like the Lorentz covariance and the continuity equation for the probability density are verified. To this end using the properti...
Relating Time-Dependent Acceleration and Height Using an Elevator
Kinser, Jason M.
2015-01-01
A simple experiment in relating a time-dependent linear acceleration function to height is explored through the use of a smartphone and an elevator. Given acceleration as a function of time, a(t), the velocity function and position functions are determined through integration as in v(t)=? a(t) dt (1) and x(t)=? v(t) dt. Mobile devices such as…
Tiny graviton matrix theory on time-dependent background
Energy Technology Data Exchange (ETDEWEB)
Chen Bin [Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China)], E-mail: bchen01@pku.edu.cn; Liu Xiao [Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China)], E-mail: liuxiaoerty@pku.edu.cn
2009-04-11
In this article we construct a tiny graviton matrix model for type IIB string theory on a plane-wave background with null dilaton. For the linear null dilaton case, we analyze its vacuum and the excitation spectrum around the vacuum, and discuss the time-dependent fuzzy three-sphere solutions and their evolution. It turns out that at very late time the non-Abelian fuzzy degrees of freedom disappear, which indicates the appearance of perturbative strings.
Exact Invariants for a Time-Dependent Hamiltonian System
Institute of Scientific and Technical Information of China (English)
LUO Xiao-Bing
2009-01-01
We have a classical look for a quantum system which is exactly solvable. We construct the invariant manifolds analytically, and then apply the semiclassical quantization rules in a final step to compute the quasienergies. The invariant is obtained by performing a canonical transformation of the initially time-dependent Hamiltonian to a time-independent one. The correspondence between classical and quantum mechanics is elucidated.
Infliximab dependency is related to decreased surgical rates in adult Crohn's disease patients
DEFF Research Database (Denmark)
Pedersen, N.; Duricova, D.; Lenicek, M.
2010-01-01
last intended infusion: prolonged response (maintenance of complete/partial response), infliximab dependency (relapse requiring repeated infusions to regain complete/partial response or need of infliximab > 12 months to sustain response). Results Forty-seven percent obtained prolonged response, 29...... on maintenance versus on demand regime was 33 and 31%, respectively (P = 0.63). No relevant clinical or genetic predictors were identified. Conclusion The infliximab dependency response seems to be equivalent to the prolonged response in adult CD patients when comparing surgery rates. Eur J Gastroenterol Hepatol......Background Infliximab dependency in children with Crohn's disease (CD) has recently been described and found to be associated with a decreased surgery rate. Aim To assess infliximab dependency of adult CD patients, evaluate the impact on surgery, and search for possible clinical and genetic...
Effective Maxwell Equations from Time-dependent Density Functional Theory
Institute of Scientific and Technical Information of China (English)
Weinan E; Jianfeng LU; Xu YANG
2011-01-01
The behavior of interacting electrons in a perfect crystal under macroscopic external electric and magnetic fields is studied. Effective Maxwell equations for the macroscopic electric and magnetic fields are derived starting from time-dependent density functional theory. Effective permittivity and permeability coefficients are obtained.
Behaviour of time-dependent materials exposed to periodical loading
Directory of Open Access Journals (Sweden)
Zupancic B.
2010-06-01
Full Text Available Paper presents methodology for analyzing behaviour of time-dependent (viscoelastic materials when exposed to periodical (cyclic loading. Within each loading cycle time-dependent material undergoes a combination of the creep and retardation process. At certain conditions the retardation process between two loading cycles cannot be fully completed to a strain free state. Consequently, strain starts to accumulate, which leads to hardening of the material and ultimately to the failure of polymeric product. Critical frequency of the applied periodical loading depends on the material retardation time (location of mechanical spectrum, while the magnitude of accumulated strain on the strength of corresponding discrete spectrum lines. The shape of mechanical spectrum defines the intensity and the magnitude of accumulated strain. Thus, the mechanical spectrum of time-dependent material is the most important function for predicting durability of dynamically loaded polymeric products. In continuation we present mathematical methodology for predicting durability of periodically loaded polymeric components of drive belt. Methodology includes numerical calculations of accumulated strain as a function of the number of loading cycles and function of loading angular velocity. Based on these calculations we can determine the critical angular velocity area of periodical loading where the strain accumulation is the most intensive.
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.
Discovery of Fourier-dependent time lags in cataclysmic variables
Scaringi, S.; Körding, E.; Groot, P.J.; Uttley, P.; Marsh, T.; Knigge, C.; Maccarone, T.; Dhillon, V.S.
2013-01-01
We report the first study of Fourier-frequency-dependent coherence and phase/time lags at optical wavelengths of cataclysmic variables (MV Lyr and LU Cam) displaying typical flickering variability in white light. Observations were performed on the William Herschel Telescope using ULTRACAM. Light
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.
Time-dependent radiation dose simulations during interplanetary space flights
Dobynde, Mikhail; Shprits, Yuri; Drozdov, Alexander; Hoffman, Jeffrey; Li, Ju
2016-07-01
Space radiation is one of the main concerns in planning long-term interplanetary human space missions. There are two main types of hazardous radiation - Solar Energetic Particles (SEP) and Galactic Cosmic Rays (GCR). Their intensities and evolution depend on the solar activity. GCR activity is most enhanced during solar minimum, while the most intense SEPs usually occur during the solar maximum. SEPs are better shielded with thick shields, while GCR dose is less behind think shields. Time and thickness dependences of the intensity of these two components encourage looking for a time window of flight, when radiation intensity and dose of SEP and GCR would be minimized. In this study we combine state-of-the-art space environment models with GEANT4 simulations to determine the optimal shielding, geometry of the spacecraft, and launch time with respect to the phase of the solar cycle. The radiation environment was described by the time-dependent GCR model, and the SEP spectra that were measured during the period from 1990 to 2010. We included gamma rays, electrons, neutrons and 27 fully ionized elements from hydrogen to nickel. We calculated the astronaut's radiation doses during interplanetary flights using the Monte-Carlo code that accounts for the primary and the secondary radiation. We also performed sensitivity simulations for the assumed spacecraft size and thickness to find an optimal shielding. In conclusion, we present the dependences of the radiation dose as a function of launch date from 1990 to 2010, for flight durations of up to 3 years.
Time- and temperature-dependent failures of a bonded joint
Energy Technology Data Exchange (ETDEWEB)
Sihn, Sangwook; Miyano, Yasushi; Tsai, S.W. [Stanford Univ., Palo Alto, CA (United States)
1997-07-01
Time and temperature dependent properties of a tubular lap bonded joint are reported. The joint bonds a cast iron rod and a composite pipe together with an epoxy type of an adhesive material containing chopped glass fiber. A new fabrication method is proposed.
Simulation of time-dependent Heisenberg models in one dimension
DEFF Research Database (Denmark)
Volosniev, A. G.; Hammer, H. -W.; Zinner, N. T.
2016-01-01
In this Letter, we provide a theoretical analysis of strongly interacting quantum systems confined by a time-dependent external potential in one spatial dimension. We show that such systems can be used to simulate spin chains described by Heisenberg Hamiltonians in which the exchange coupling...
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)
Introduction to quantum mechanics a time-dependent perspective
Tannor, David J
2007-01-01
"Introduction to Quantum Mechanics" covers quantum mechanics from a time-dependent perspective in a unified way from beginning to end. Intended for upper-level undergraduate and graduate courses this text will change the way people think about and teach quantum mechanics in chemistry and physics departments.
Time-dependent effects of cardiovascular exercise on memory
DEFF Research Database (Denmark)
Roig, Marc; Thomas, Richard; Mang, Cameron S
2016-01-01
We present new evidence supporting the hypothesis that the effects of cardiovascular exercise on memory can be regulated in a time-dependent manner. When the exercise stimulus is temporally coupled with specific phases of the memory formation process, a single bout of cardiovascular exercise may ...
Multicomponent density-functional theory for time-dependent systems
Butriy, O.; Ebadi, H.; de Boeij, P. L.; van Leeuwen, R.; Gross, E. K. U.
2007-01-01
We derive the basic formalism of density functional theory for time-dependent electron-nuclear systems. The basic variables of this theory are the electron density in body-fixed frame coordinates and the diagonal of the nuclear N-body density matrix. The body-fixed frame transformation is carried ou
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.
Time dependent behavior of cores from the Pleasant Bayou wells
Energy Technology Data Exchange (ETDEWEB)
Thompson, T.W.; Jogi, P.N.; Gray, K.E.; Richardson, J.; Bebout, D.G.; Bachman, A.L. (eds.)
1981-01-01
Results of constant-load creep tests on sands from the Pleasant Bayou wells are reported. Significant time dependent behavior under both hydrostatic and non-hydrostatic states of stress have been fit to linear rheological models. The data and models are reported.
Linear-response thermal time-dependent density functional theory
Pribram-Jones, Aurora; Burke, Kieron
2015-01-01
The van Leeuwen proof of linear-response time-dependent density functional theory (TDDFT) is generalized to thermal ensembles. This allows generalization to finite temperatures of the Gross-Kohn relation, the exchange-correlation kernel of TDDFT, and fluctuation dissipation theorem for DFT. This produces a natural method for generating new thermal exchange-correlation (XC) approximations.
Numerical analysis of time-dependent Boussinesq models
Houwen, P.J. van der; Mooiman, J.; Wubs, F.W.
1991-01-01
In this paper we analyse numerical models for time-dependent Boussinesq equations. These equations arise when so-called Boussinesq terms are introduced into the shallow water equations. We use the Boussinesq terms proposed by Katapodes and Dingemans. These terms generalize the constant depth terms g
Simulating transient dynamics of the time-dependent time fractional Fokker-Planck systems
Kang, Yan-Mei
2016-09-01
For a physically realistic type of time-dependent time fractional Fokker-Planck (FP) equation, derived as the continuous limit of the continuous time random walk with time-modulated Boltzmann jumping weight, a semi-analytic iteration scheme based on the truncated (generalized) Fourier series is presented to simulate the resultant transient dynamics when the external time modulation is a piece-wise constant signal. At first, the iteration scheme is demonstrated with a simple time-dependent time fractional FP equation on finite interval with two absorbing boundaries, and then it is generalized to the more general time-dependent Smoluchowski-type time fractional Fokker-Planck equation. The numerical examples verify the efficiency and accuracy of the iteration method, and some novel dynamical phenomena including polarized motion orientations and periodic response death are discussed.
Directory of Open Access Journals (Sweden)
S. Olate
2012-12-01
Full Text Available Introducción: La exodoncia de tercer molar es un procedimiento frecuente en odontología, lo que exige conocer los factores que pueden anticipar el tiempo quirúrgico y sus características. El objetivo de esta investigación es conocer los factores asociados al aumento del tiempo quirúrgico (ATQ en la exodoncia de terceros molares inferiores (3M. Material y método: 145 sujetos de entre 15 y 40 años fueron seleccionados desde tres centros quirúrgicos de Temuco (Chile, en los que fueron realizados 158 cirugías; todos los pacientes consultaron por exodoncia de tercer molar siendo operados en tales centros. Las variables del paciente, del diente y de la cirugía fueron estudiadas; la información fue analizada con el paquete estadístico Stata 9.1, empleando en test de Fisher y chi cuadrado con pIntroduction: Everyday, the third molar's surgery is more frequent. That fact makes necessary to know the factors that allow to anticipate the surgical time and its characteristics. The aim of this research was to know the pre-surgical and surgical factors associated with the increase of the surgical time (IST of the mandibular third molar (3M's surgery. Methodology: 145 subjects between the 15-40 years-oldwere selected from three surgical centers of Temuco (Chile. In this enclousures 158 surgeries were realized. All of the patients consulted by a 3M' s surgery, being put under surgical extraction in this centers. Variables from the patients, tooth and surgery itself were studied. The information were analyzed in the Stata 9.1 statistical package, utilizing the Fisher Test and Chi-Square Test,with p<0,05 for statistical significance. Results: The surgical time used in the surgery was minorof 20 minutes in the 50% of the cases and minor of de 30 minutes in the 75 % ofthe cases. The patient's age, the molar's position, the presence of pericoronaritis and the 3M' s root anatomy were significantly associated with a IST (p<0,05, of equal way the flap
Denard, Patrick J.; Dai, Xuesong; Burkhart, Stephen S.
2015-01-01
Purpose: Our purpose was to determine the relationship between number of preoperative shoulder dislocations and total dislocation time and the need to perform bone deficiency procedures at the time of primary anterior instability surgery. Our hypothesis was that need for bone deficiency procedures would increase with the total number and hours of dislocation. Materials and Methods: A retrospective review was performed of primary instability surgeries performed by a single surgeon. Patients with 25% glenoid bone loss were treated with Latarjet reconstruction. Number of dislocations and total dislocation time were examined for their relationship with the treatment method. Results: Ten arthroscopic Bankart repairs, 13 arthroscopic Bankart plus remplissage procedures, and 9 Latarjet reconstructions were available for review. Total dislocations (P = 0.012) and total hours of dislocation (P = 0.019) increased from the Bankart, to the remplissage, to the Latarjet groups. Patients with a total dislocation time of 5 h or more were more likely to require a Latarjet reconstruction (P = 0.039). Patients with only 1 preoperative dislocation were treated with an isolated Bankart repair in 64% (7 of 11) of cases, whereas those with 2 or more dislocations required a bone loss procedure in 86% (18 of 21) of cases (P = 0.013). Conclusion: Increasing number of dislocations and total dislocation time are associated with the development of glenoid and humeral head bony lesions that alter surgical management of anterior shoulder instability. The necessity for the addition of a remplissage to an arthroscopic Bankart repair or the use of a Latarjet reconstruction increases with only 1 recurrent dislocation. Level of evidence: Level III, retrospective comparative study. PMID:25709237
Time-Dependent Networks as Models to Achieve Fast Exact Time-Table Queries
DEFF Research Database (Denmark)
Brodal, Gert Stølting; Jacob, Rico
2003-01-01
We consider efficient algorithms for exact time-table queries, i.e. algorithms that find optimal itineraries for travelers using a train system. We propose to use time-dependent networks as a model and show advantages of this approach over space-time networks as models.......We consider efficient algorithms for exact time-table queries, i.e. algorithms that find optimal itineraries for travelers using a train system. We propose to use time-dependent networks as a model and show advantages of this approach over space-time networks as models....
Time-dependent Networks as Models to Achieve Fast Exact Time-table Queries
DEFF Research Database (Denmark)
Brodal, Gerth Stølting; Jacob, Rico
2001-01-01
We consider efficient algorithms for exact time-table queries, i.e. algorithms that find optimal itineraries. We propose to use time-dependent networks as a model and show advantages of this approach over space-time networks as models.......We consider efficient algorithms for exact time-table queries, i.e. algorithms that find optimal itineraries. We propose to use time-dependent networks as a model and show advantages of this approach over space-time networks as models....
Energy Technology Data Exchange (ETDEWEB)
Bhargava, Kapilesh, E-mail: kapil_66@barc.gov.i [Architecture and Civil Engineering Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Mori, Yasuhiro [Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8603 (Japan); Ghosh, A.K. [Reactor Safety Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India)
2011-05-15
This paper forms the third part of a study which addresses time-dependent reliability analyses of reinforced concrete (RC) beams affected by reinforcement corrosion. Parts 1 and 2 of the reliability study are presented in companion papers. Part 1 of the reliability study presents evaluation of probabilistic descriptions for time-dependent strengths of a typical simply supported corrosion-affected RC beam. These probabilistic descriptions, i.e., mean and coefficient of variation (c.o.v.) for the time-dependent strengths are presented for two limit states: (a) flexural failure; and (b) shear failure. Part 2 of the reliability study presents evaluation of time-dependent failure probability for the considered RC beam by utilizing the information on probabilistic descriptions for time-dependent strengths available in Part 1. Evaluation of time-dependent failure probability considering the variability in time-dependent strengths and/or time-dependent degradation functions is also presented. This paper investigates the effects of time to corrosion initiation and its variability on failure probability of the same RC beam presented in companion papers. By considering variability in the identified variables that could affect the expected time of first corrosion, simple estimations are presented for mean time to corrosion initiation and variability associated with time to corrosion initiation. Evaluation of time-dependent failure probability for the beam is presented by considering estimated probabilistic descriptions, i.e., mean and c.o.v. for time to corrosion initiation. Parametric analyses show that failure probability for the beam is sensitive to the mode of strength degradation and time to corrosion initiation.
Time-dependent coupled-cluster method for atomic nuclei
Pigg, D A; Nam, H; Papenbrock, T
2012-01-01
We study time-dependent coupled-cluster theory in the framework of nuclear physics. Based on Kvaal's bi-variational formulation of this method [S. Kvaal, arXiv:1201.5548], we explicitly demonstrate that observables that commute with the Hamiltonian are conserved under time evolution. We explore the role of the energy and of the similarity-transformed Hamiltonian under real and imaginary time evolution and relate the latter to similarity renormalization group transformations. Proof-of-principle computations of He-4 and O-16 in small model spaces, and computations of the Lipkin model illustrate the capabilities of the method.
Time-dependant cosmological interpretation of quantum mechanics
Moulay, Emmanuel
2015-01-01
The aim of this article is to define a time-dependant cosmological interpretation of quantum mechanics in the context of a multiverse coming from eternal inflation. A common notion of time is defined for observers in similar observable universes by using the holographic principle. It is the time elapsed since the post-inflationary epoch. With this improvement, the cosmological interpretation of quantum mechanics becomes a full interpretation of quantum mechanics where the unitary evolution of quantum states is preserved. Moreover, it is well suited for eternal inflation .
Model Penjadwalan Batch Multi Item dengan Dependent Processing Time
Directory of Open Access Journals (Sweden)
Sukoyo Sukoyo
2010-01-01
Full Text Available This paper investigates a development of single machine batch scheduling for multi items with dependent processing time. The batch scheduling problem is to determine simultaneously number of batch (N, which item and its size allocated for each batch, and processing sequences of resulting batches. We use total actual flow time as the objective of schedule performance. The multi item batch scheduling problem could be formulated into a biner-integer nonlinear programming model because the number of batch should be in integer value, the allocation of items to resulting batch need binary values, and also there are some non-linearity on objective function and constraint due to the dependent processing time. By applying relaxation on the decision variable of number of batch (N as parameter, a heuristic procedure could be applied to find solution of the single machine batch scheduling problem for multi items.
Time-Dependent Warping and Non-Singular Bouncing Cosmologies
Balasubramanian, Koushik
2014-01-01
In this note, we construct a family of non-singular time-dependent solutions of a six-dimensional gravitational theory that are warped products of a four dimensional bouncing cosmological solution and a two dimensional internal manifold. The warp factor is time-dependent and breaks translation invariance along one of the internal directions. When the warp factor is periodic in time, the non-compact part of the geometry bounces periodically. The six dimensional geometry is supported by matter that does not violate the null energy condition. We show that this 6D geometry does not admit a closed trapped surface and hence the Hawking-Penrose singularity theorems do not apply to these solutions. We also present examples of singular solutions where the topology of the internal manifold changes dynamically.
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.
Scintillation time dependence and pulse shape discrimination in liquid argon
Lippincott, W H; Gastler, D; Hime, A; Kearns, E; McKinsey, D N; Nikkel, J A; Stonehill, L C
2008-01-01
Using a single-phase liquid argon detector with a signal yield of 4.85 photoelectrons per keV of electronic-equivalent recoil energy (keVee), we measure the scintillation time dependence of both electronic and nuclear recoils in liquid argon down to 5 keVee. We develop two methods of pulse shape discrimination to distinguish between electronic and nuclear recoils. Using one of these methods, we measure a background and statistics-limited level of electronic recoil contamination to be $7.6\\times10^{-7}$ between 60 and 128 keV of nuclear recoil energy (keVr) for a nuclear recoil acceptance of 50% with no nuclear recoil-like events above 72 keVr. Finally, we develop a maximum likelihood method of pulse shape discrimination using the measured scintillation time dependence and predict the sensitivity to WIMP-nucleon scattering in three configurations of a liquid argon dark matter detector.
Eisenhart lifts and symmetries of time-dependent systems
Cariglia, M; Gibbons, G W; Horvathy, P A
2016-01-01
Certain dissipative systems, such as Caldirola and Kannai's damped simple harmonic oscillator, may be modelled by time-dependent Lagrangian and hence time dependent Hamiltonian systems with $n$ degrees of freedom. In this paper we treat these systems, their projective and conformal symmetries as well as their quantisation from the point of view of the Eisenhart lift to a Bargmann spacetime in $n+2$ dimensions, equipped with its covariantly constant null Killing vector field. Reparametrization of the time variable corresponds to conformal rescalings of the Bargmann metric. We show how the Arnold map lifts to Bargmann spacetime. We contrast the greater generality of the Caldirola-Kannai approach with that of Arnold and Bateman. At the level of quantum mechanics, we are able to show how the relevant Schr\\"odinger equation emerges naturally using the techniques of quantum field theory in curved spacetimes, since a covariantly constant null Killing vector field gives rise to well defined one particle Hilbert space...
Effective field theory in time-dependent settings
Collins, Hael; Ross, Andreas
2012-01-01
We use the in-in or Schwinger-Keldysh formalism to explore the construction and interpretation of effective field theories for time-dependent systems evolving out of equilibrium. Starting with a simple model consisting of a heavy and a light scalar field taken to be in their free vacuum states at a finite initial time, we study the effects from the heavy field on the dynamics of the light field by analyzing the equation of motion for the expectation value of the light background field. New terms appear which cannot arise from a local action of an effective field theory in terms of the light field, though they disappear in the adiabatic limit. We discuss the origins of these terms as well as their possible implications for time dependent situations such as inflation.
Time-dependent phase error correction using digital waveform synthesis
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin W.; Buskirk, Stephen
2017-10-10
The various technologies presented herein relate to correcting a time-dependent phase error generated as part of the formation of a radar waveform. A waveform can be pre-distorted to facilitate correction of an error induced into the waveform by a downstream operation/component in a radar system. For example, amplifier power droop effect can engender a time-dependent phase error in a waveform as part of a radar signal generating operation. The error can be quantified and an according complimentary distortion can be applied to the waveform to facilitate negation of the error during the subsequent processing of the waveform. A time domain correction can be applied by a phase error correction look up table incorporated into a waveform phase generator.
Time-dependent viscoelastic behavior of an LDPE melt
Institute of Scientific and Technical Information of China (English)
Shuxin Huang; Chuanjing Lu; Yurun Fan
2006-01-01
Two differential constitutive equations,i.e.Giesekus model and Johnson-Segalman model were employed here to predict the time-dependent viscoelastic behavior of an LDPE melt in thixotropy-loop experiments and step shear rate experiment. Multiple relaxation modes were adopted, and the parameters used to describe the nonlinear viscoelasticity in the two models were obtained by fitting the shear-thinning viscosity. The predictions on those transient shear characteristics by the two models are found in qualitative agreement with our previous experiments. Johnson-Segalman model predicts oscillation behavior in the thixotropy-loop and step shear rate experiments, whereas Giesekus model does not. Both models predict higher shear stresses than the experimental data in the case of long time shearing, implying that both models are not able to completely characterize the time-dependent shear stress of the-melt at high shear rate.
Student understanding of time dependence in quantum mechanics
Emigh, Paul J.; Passante, Gina; Shaffer, Peter S.
2015-12-01
[This paper is part of the Focused Collection on Upper Division Physics Courses.] The time evolution of quantum states is arguably one of the more difficult ideas in quantum mechanics. In this article, we report on results from an investigation of student understanding of this topic after lecture instruction. We demonstrate specific problems that students have in applying time dependence to quantum systems and in recognizing the key role of the energy eigenbasis in determining the time dependence of wave functions. Through analysis of student responses to a set of four interrelated tasks, we categorize some of the difficulties that underlie common errors. The conceptual and reasoning difficulties that have been identified are illustrated through student responses to four sets of questions administered at different points in a junior-level course on quantum mechanics. Evidence is also given that the problems persist throughout undergraduate instruction and into the graduate level.
Izumi, Chisato
2015-03-01
Severe tricuspid regurgitation may often appear and progress late after left-sided valve surgery without left-sided valve dysfunction, significant left heart failure, and pulmonary hypertension. The clinical features, echocardiographic evaluation, treatment, and prognosis of this disease entity have been discussed, but data is limited compared with left-sided valve diseases. Tricuspid annular dilatation associated with atrial fibrillation and right ventricular dysfunction strongly relate to development of isolated tricuspid regurgitation late after left-sided valve surgery. Three-dimensional evaluation may be useful in evaluating tricuspid valve anatomy in more detail. Better prognosis in patients undergoing surgical treatment for severe isolated tricuspid regurgitation than those who were treated medically has been reported; however, the timing of isolated tricuspid valve surgery is often too late. Right ventricular function is a key word for determining the timing of isolated tricuspid valve surgery; however, it is difficult to evaluate by conventional echocardiography. One of the serious issues in the future will be how to accurately evaluate right ventricular function.
Infliximab dependency is related to decreased surgical rates in adult Crohn's disease patients
DEFF Research Database (Denmark)
Pedersen, N.; Duricova, D.; Lenicek, M.
2010-01-01
Background Infliximab dependency in children with Crohn's disease (CD) has recently been described and found to be associated with a decreased surgery rate. Aim To assess infliximab dependency of adult CD patients, evaluate the impact on surgery, and search for possible clinical and genetic...... predictors. Methods Two hundred and forty-five CD patients treated with infliximab were included from Danish and Czech Crohn Colitis Database (1999-2006). Infliximab response was assessed as immediate outcome, 1 month after infliximab start: complete, partial, and no response. Three months outcome, after...
Time-dependent magnetohydrodynamic simulations of the inner heliosphere
Merkin, V. G.; Lyon, J. G.; Lario, D.; Arge, C. N.; Henney, C. J.
2016-04-01
This paper presents results from a simulation study exploring heliospheric consequences of time-dependent changes at the Sun. We selected a 2 month period in the beginning of year 2008 that was characterized by very low solar activity. The heliosphere in the equatorial region was dominated by two coronal holes whose changing structure created temporal variations distorting the classical steady state picture of the heliosphere. We used the Air Force Data Assimilate Photospheric Flux Transport (ADAPT) model to obtain daily updated photospheric magnetograms and drive the Wang-Sheeley-Arge (WSA) model of the corona. This leads to a formulation of a time-dependent boundary condition for our three-dimensional (3-D) magnetohydrodynamic (MHD) model, LFM-helio, which is the heliospheric adaptation of the Lyon-Fedder-Mobarry MHD simulation code. The time-dependent coronal conditions were propagated throughout the inner heliosphere, and the simulation results were compared with the spacecraft located near 1 astronomical unit (AU) heliocentric distance: Advanced Composition Explorer (ACE), Solar Terrestrial Relations Observatory (STEREO-A and STEREO-B), and the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft that was in cruise phase measuring the heliospheric magnetic field between 0.35 and 0.6 AU. In addition, during the selected interval MESSENGER and ACE aligned radially allowing minimization of the effects of temporal variation at the Sun versus radial evolution of structures. Our simulations show that time-dependent simulationsreproduce the gross-scale structure of the heliosphere with higher fidelity, while on smaller spatial and faster time scales (e.g., 1 day) they provide important insights for interpretation of the data. The simulations suggest that moving boundaries of slow-fast wind transitions at 0.1 AU may result in the formation of inverted magnetic fields near pseudostreamers which is an intrinsically time-dependent process
Time and space dependent backgrounds from nonsupersymmetric strings
Dudas, E A; Timirgaziu, C
2003-01-01
We investigate maximally symmetric backgrounds in nonsupersymmetric string vacua with D-branes and O-planes localized in the compact space. We find a class of solutions with a perturbative string coupling constant in all regions of spacetime. Depending on the particular model, we find either a time evolution with a big-bang type singularity or a space dependent background with generically orbifold singularities. We show that the result can be interpreted as a supersymmetric bulk with some symmetries broken by the boundaries. We also discuss an interesting connection to Lorentzian and Euclidian orbifolds.
Observation of detection-dependent multi-photon coherence times
DEFF Research Database (Denmark)
Ra, Young-Sik; Tichy, Malte C.; Lim, Hyang-Tag
2013-01-01
The coherence time constitutes one of the most critical parameters that determines whether or not interference is observed in an experiment. For photons, it is traditionally determined by the effective spectral bandwidth of the photon. Here we report on multi-photon interference experiments...... this dependence, which can be attributed to higher-order effects in the mutual indistinguishability of the particles. As a striking consequence, a single, well-defined many-particle quantum state can exhibit qualitatively different degrees of interference, depending on the chosen observable. Therefore, optimal...
Amraoui, Sana; Barandon, Laurent; Whinnett, Zachary; Ploux, Sylvain; Labrousse, Louis; Denis, Arnaud; Oses, Pierre; Ritter, Philippe; Haissaguerre, Michel; Bordachar, Pierre
2013-08-01
Management of pacemaker infection in pacing-dependent patients is often challenging. Typically, temporary pacing is used while antibiotic therapy is given for a number of days before reimplantation of a new endocardial system. This results in a prolonged hospital stay and complications associated with temporary pacing. In this study, we examine the feasibility of performing a single combined procedure of epicardial pacemaker implantation followed by system extraction. One hundred consecutive infected pacemaker-dependent patients underwent implantation of 2 epicardial ventricular leads and were converted to a ventricular demand pacing system. The infected pacing system was then extracted during the same procedure. Patients were followed up for 12 months. Significant pericardial bleeding developed during the procedure in 3 patients. The presence of the pericardial drain positioned during the implantation of the epicardial pacing system meant that cardiac tamponade did not occur, allowing surgical repair with sternotomy to be carried out under stable hemodynamic conditions. Two of these 100 patients died in the 30-day postoperative period; 1 death was due to septic shock and 1 to pulmonary distress. Median 1-year epicardial pacing thresholds were stable and excellent (1.4 ± 0.9 volts). However, 1 of the 2 leads developed increased thresholds in 6 patients, which led to the exclusive use of other ventricular lead. A single combined procedure of surgical epicardial pacemaker implantation and pacemaker system extraction appears to be a safe and effective method for managing pacemaker-dependent patients with infected pacemakers. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.
On the time dependence of the $h$-index
Mannella, Riccardo
2012-01-01
The time dependence of the $h$-index is analyzed by considering the average behaviour of $h$ as a function of the academic age $A_A$ for about 1400 Italian physicists, with career lengths spanning from 3 to 46 years. The individual $h$-index is strongly correlated with the square root of the total citations $N_C$: $h \\approx 0.53 \\sqrt{N_C}$. For academic ages ranging from 12 to 24 years, the distribution of the time scaled index $h/\\sqrt{A_A}$ is approximately time-independent and it is well described by the Gompertz function. The time scaled index $h/\\sqrt{A_A}$ has an average approximately equal to 3.8 and a standard deviation approximately equal to 1.6. Finally, the time scaled index $h/\\sqrt{A_A}$ appears to be strongly correlated with the contemporary $h$-index $h_c$.
Neutrino flavor instabilities in a time-dependent supernova model
Directory of Open Access Journals (Sweden)
Sajad Abbar
2015-12-01
Full Text Available A dense neutrino medium such as that inside a core-collapse supernova can experience collective flavor conversion or oscillations because of the neutral-current weak interaction among the neutrinos. This phenomenon has been studied in a restricted, stationary supernova model which possesses the (spatial spherical symmetry about the center of the supernova and the (directional axial symmetry around the radial direction. Recently it has been shown that these spatial and directional symmetries can be broken spontaneously by collective neutrino oscillations. In this letter we analyze the neutrino flavor instabilities in a time-dependent supernova model. Our results show that collective neutrino oscillations start at approximately the same radius in both the stationary and time-dependent supernova models unless there exist very rapid variations in local physical conditions on timescales of a few microseconds or shorter. Our results also suggest that collective neutrino oscillations can vary rapidly with time in the regimes where they do occur which need to be studied in time-dependent supernova models.
Eisenhart lifts and symmetries of time-dependent systems
Cariglia, M.; Duval, C.; Gibbons, G. W.; Horváthy, P. A.
2016-10-01
Certain dissipative systems, such as Caldirola and Kannai's damped simple harmonic oscillator, may be modelled by time-dependent Lagrangian and hence time dependent Hamiltonian systems with n degrees of freedom. In this paper we treat these systems, their projective and conformal symmetries as well as their quantisation from the point of view of the Eisenhart lift to a Bargmann spacetime in n + 2 dimensions, equipped with its covariantly constant null Killing vector field. Reparametrisation of the time variable corresponds to conformal rescalings of the Bargmann metric. We show how the Arnold map lifts to Bargmann spacetime. We contrast the greater generality of the Caldirola-Kannai approach with that of Arnold and Bateman. At the level of quantum mechanics, we are able to show how the relevant Schrödinger equation emerges naturally using the techniques of quantum field theory in curved spacetimes, since a covariantly constant null Killing vector field gives rise to well defined one particle Hilbert space. Time-dependent Lagrangians arise naturally also in cosmology and give rise to the phenomenon of Hubble friction. We provide an account of this for Friedmann-Lemaître and Bianchi cosmologies and how it fits in with our previous discussion in the non-relativistic limit.
Time-dependent tomographic reconstruction of the solar corona
Vibert, D.; Peillon, C.; Lamy, P.; Frazin, R. A.; Wojak, J.
2016-10-01
Solar rotational tomography (SRT) applied to white-light coronal images observed at multiple aspect angles has been the preferred approach for determining the three-dimensional (3D) electron density structure of the solar corona. However, it is seriously hampered by the restrictive assumption that the corona is time-invariant which introduces significant errors in the reconstruction. We first explore several methods to mitigate the temporal variation of the corona by decoupling the "fast-varying" inner corona from the "slow-moving" outer corona using multiple masking (either by juxtaposition or recursive combination) and radial weighting. Weighting with a radial exponential profile provides some improvement over a classical reconstruction but only beyond ≈ 3R⊙. We next consider a full time-dependent tomographic reconstruction involving spatio-temporal regularization and further introduce a co-rotating regularization aimed at preventing concentration of reconstructed density in the plane of the sky. Crucial to testing our procedure and properly tuning the regularization parameters is the introduction of a time-dependent MHD model of the corona based on observed magnetograms to build a time-series of synthetic images of the corona. Our procedure, which successfully reproduces the time-varying model corona, is finally applied to a set of 53 LASCO-C2 pB images roughly evenly spaced in time from 15 to 29 March 2009. Our procedure paves the way to a time-dependent tomographic reconstruction of the coronal electron density to the whole set of LASCO-C2 images presently spanning 20 years.
Time and frequency dependent rheology of reactive silica gels.
Wang, Miao; Winter, H Henning; Auernhammer, Günter K
2014-01-01
In a mixture of sodium silicate and low concentrated sulfuric acid, nano-sized silica particles grow and may aggregate to a system spanning gel network. We studied the influence of the finite solubility of silica at high pH on the mechanical properties of the gel with classical and piezo-rheometers. Direct preparation of the gel sample in the rheometer cell avoided any pre-shear of the gel structure during the filling of the rheometer. The storage modulus of the gel grew logarithmically with time with two distinct growth laws. The system passes the gel point very quickly but still shows relaxation at low frequency, typically below 6 rad/s. We attribute this as a sign of structural rearrangements due to the finite solubility of silica at high pH. The reaction equilibrium between bond formation and dissolution maintains a relatively large bond dissolution rate, which leads to a finite life time of the bonds and behavior similar to physical gels. This interpretation is also compatible with the logarithmic time dependence of the storage modulus. The frequency dependence was more pronounced for lower water concentrations, higher temperatures and shorter reaction times. With two relaxation models (the modified Cole-Cole model and the empirical Baumgaertel-Schausberger-Winter model) we deduced characteristic times from the experimental data. Both models approximately described the data and resulted in similar relaxation times.
Progress Report on Alloy 617 Time Dependent Allowables
Energy Technology Data Exchange (ETDEWEB)
Wright, Julie Knibloe [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2015-06-01
Time dependent allowable stresses are required in the ASME Boiler and Pressure Vessel Code for design of components in the temperature range where time dependent deformation (i.e., creep) is expected to become significant. There are time dependent allowable stresses in Section IID of the Code for use in the non-nuclear construction codes, however, there are additional criteria that must be considered in developing time dependent allowables for nuclear components. These criteria are specified in Section III NH. St is defined as the lesser of three quantities: 100% of the average stress required to obtain a total (elastic, plastic, primary and secondary creep) strain of 1%; 67% of the minimum stress to cause rupture; and 80% of the minimum stress to cause the initiation of tertiary creep. The values are reported for a range of temperatures and for time increments up to 100,000 hours. These values are determined from uniaxial creep tests, which involve the elevated temperature application of a constant load which is relatively small, resulting in deformation over a long time period prior to rupture. The stress which is the minimum resulting from these criteria is the time dependent allowable stress St. In this report data from a large number of creep and creep-rupture tests on Alloy 617 are analyzed using the ASME Section III NH criteria. Data which are used in the analysis are from the ongoing DOE sponsored high temperature materials program, form Korea Atomic Energy Institute through the Generation IV VHTR Materials Program and historical data from previous HTR research and vendor data generated in developing the alloy. It is found that the tertiary creep criterion determines St at highest temperatures, while the stress to cause 1% total strain controls at low temperatures. The ASME Section III Working Group on Allowable Stress Criteria has recommended that the uncertainties associated with determining the onset of tertiary creep and the lack of significant
Assessment of operative times of multiple surgical specialties in a public university hospital.
Costa, Altair da Silva
2017-01-01
To evaluate the indicators duration of anesthesia, operative time and time patients stay in the operating rooms of different surgical specialties at a public university hospital. It was done by a descriptive cross-sectional study based on the operating room database. The following stages were measured: duration of anesthesia, procedure time and patient length of stay in the room of the various specialties. We included surgeries carried out in sequence in the same room, between 7:00 a.m. and 5 p.m., either elective or emergency. We calculated the 80th percentile of the stages, where 80% of procedures were below this value. The study measured 8,337 operations of 12 surgical specialties performed within one year. The overall mean duration of anesthesia of all specialties was 178.12±110.46 minutes, and the 80th percentile was 252 minutes. The mean operative time was 130.45±97.23 minutes, and the 80th percentile was 195 minutes. The mean total time of the patient in the operating room was 197.30±113.71 minutes, and the 80th percentile was 285 minutes. Thus, the variation of the overall mean compared to the 80th percentile was 41% for anesthesia, 49% for surgeries and 44% for operating room time. In average, anesthesia took up 88% of the operating room period, and surgery, 61%. This study identified patterns in the duration of surgery stages. The mean values of the specialties can assist with operating room planning and reduce delays. Avaliar os indicadores de tempo da anestesia, da operação e da permanência do paciente em sala de diversas especialidades do centro cirúrgico de um hospital universitário. Foi realizado em estudo descritivo transversal a partir da base de dados do centro cirúrgico e mensuradas as seguintes etapas: duração de anestesia, tempo do procedimento e tempo de permanência do paciente em sala das diversas especialidades. Foram incluídas as operações realizadas em sequência na mesma sala, das 7h às 17h, eletivas ou de urg
The Nonlinear Dynamics of Time Dependent Subcritical Baroclinic Currents
Pedlosky, J.; Flierl, G. R.
2006-12-01
The nonlinear dynamics of baroclinically unstable waves in a time dependent zonal shear flow is considered in the framework of the two-layer Phillips model on the beta plane. In most cases considered in this study the amplitude of the shear is well below the critical value of the steady shear version of the model. Nevertheless, the time dependent problem in which the shear oscillates periodically is unstable, and the unstable waves grow to substantial amplitudes, in some cases with strongly nonlinear and turbulent characteristics. For very small values of the shear amplitude in the presence of dissipation an analytical, asymptotic theory predicts a self-sustained wave whose amplitude undergoes a nonlinear oscillation whose period is amplitude dependent. There is a sensitive amplitude dependence of the wave on the frequency of the oscillating shear when the shear amplitude is small. This behavior is also found in a truncated model of the dynamics, and that model is used to examine larger shear amplitudes. When there is a mean value of the shear in addition to the oscillating component, but such that the total shear is still subcritical, the resulting nonlinear states exhibit a rectified horizontal buoyancy flux with a nonzero time average as a result of the instability of the oscillating shear. For higher, still subcritical, values of the shear we have detected a symmetry breaking in which a second cross-stream mode is generated through an instability of the unstable wave although this second mode would by itself be stable on the basic time dependent current. For shear values that are substantially subcritical but of order of the critical shear, calculations with a full quasi-geostrophic numerical model reveal a turbulent flow generated by the instability. If the beta effect is disregarded the inviscid, linear problem is formally stable. However, our calculations show that a small degree of nonlinearity is enough to destabilize the flow leading to large amplitude
FREQUENCY-DEPENDENT DISPERSION MEASURES AND IMPLICATIONS FOR PULSAR TIMING
Energy Technology Data Exchange (ETDEWEB)
Cordes, J. M. [Astronomy Department, Cornell University, Ithaca, NY 14853 (United States); Shannon, R. M. [CSIRO Astronomy and Space Science, Box 76, Epping, NSW 1710 (Australia); Stinebring, D. R., E-mail: cordes@astro.cornell.edu, E-mail: ryan.shannon@csiro.au, E-mail: dan.stinebring@oberlin.edu [Department of Physics and Astronomy, Oberlin College, Oberlin, OH 44074 (United States)
2016-01-20
The dispersion measure (DM), the column density of free electrons to a pulsar, is shown to be frequency dependent because of multipath scattering from small-scale electron-density fluctuations. DMs vary between propagation paths whose transverse extent varies strongly with frequency, yielding arrival times that deviate from the high-frequency scaling expected for a cold, uniform, unmagnetized plasma (1/frequency{sup 2}). Scaling laws for thin phase screens are verified with simulations; extended media are also analyzed. The rms DM difference across an octave band near 1.5 GHz is ∼ 4 × 10{sup −5} pc cm{sup −3} for pulsars at ∼1 kpc distance. The corresponding arrival-time variations are a few to hundreds of nanoseconds for DM ≲ 30 pc cm{sup −3} but increase rapidly to microseconds or more for larger DMs and wider frequency ranges. Chromatic DMs introduce correlated noise into timing residuals with a power spectrum of “low pass” form. The correlation time is roughly the geometric mean of the refraction times for the highest and lowest radio frequencies used, ranging from days to years, depending on the pulsar. We discuss implications for methodologies that use large frequency separations or wide bandwidth receivers for timing measurements. Chromatic DMs are partially mitigable by including an additional chromatic term in arrival time models. Without mitigation, an additional term in the noise model for pulsar timing is implied. In combination with measurement errors from radiometer noise, an arbitrarily large increase in total frequency range (or bandwidth) will yield diminishing benefits and may be detrimental to overall timing precision.
A test of time-dependent theories of stellar convection
Gastine, T
2011-01-01
Context: In Cepheids close to the red edge of the classical instability strip, a coupling occurs between the acoustic oscillations and the convective motions close to the surface.The best topical models that account for this coupling rely on 1-D time-dependent convection (TDC) formulations. However, their intrinsic weakness comes from the large number of unconstrained free parameters entering in the description of turbulent convection. Aims: We compare two widely used TDC models with the first two-dimensional nonlinear direct numerical simulations (DNS) of the convection-pulsation coupling in which the acoustic oscillations are self-sustained by the kappa-mechanism. Methods: The free parameters appearing in the Stellingwerf and Kuhfuss TDC recipes are constrained using a chi2-test with the time-dependent convective flux that evolves in nonlinear simulations of highly-compressible convection with kappa-mechanism. Results: This work emphasises some inherent limits of TDC models, that is, the temporal variabilit...
Origin of the spike-timing-dependent plasticity rule
Cho, Myoung Won; Choi, M. Y.
2016-08-01
A biological synapse changes its efficacy depending on the difference between pre- and post-synaptic spike timings. Formulating spike-timing-dependent interactions in terms of the path integral, we establish a neural-network model, which makes it possible to predict relevant quantities rigorously by means of standard methods in statistical mechanics and field theory. In particular, the biological synaptic plasticity rule is shown to emerge as the optimal form for minimizing the free energy. It is further revealed that maximization of the entropy of neural activities gives rise to the competitive behavior of biological learning. This demonstrates that statistical mechanics helps to understand rigorously key characteristic behaviors of a neural network, thus providing the possibility of physics serving as a useful and relevant framework for probing life.
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.
Time-dependent density functional theory: Causality and other problems
Energy Technology Data Exchange (ETDEWEB)
Ruggenthaler, Michael; Bauer, Dieter [Max-Planck-Inst. fuer Kernphysik, Heidelberg (Germany)
2007-07-01
Time-dependent density functional theory (TDDFT) is a reformulation of the time dependent many-body problem in quantum mechanics which is capable of reducing the computational cost to calculate, e.g., strongly driven many-electron systems enormously. Recent developments were able to overcome fundamental problems associated with ionization processes. Still vital issues have to be clarified. Besides the construction of the underlying functionals we investigate the causality problem of TDDFT by general considerations and by studying a exactly solvable system of two correlated electrons in an intense laser-pulse. For the latter system, the two alternative approaches to the construction of the action functional or a constrained functional derivative by van Leeuwen and Gal, respectively, are explored.
Thermal state of the general time-dependent harmonic oscillator
Indian Academy of Sciences (India)
Jeong-Ryeol Choi
2003-07-01
Taking advantage of dynamical invariant operator, we derived quantum mechanical solution of general time-dependent harmonic oscillator. The uncertainty relation of the system is always larger than ħ=2 not only in number but also in the thermal state as expected. We used the diagonal elements of density operator satisfying Leouville–von Neumann equation to calculate various expectation values in the thermal state. We applied our theory to a special case which is the forced Caldirola–Kanai oscillator.
ARTICLES: Time-Dependent Stokes Shift from Solvent Dielectric Relaxation
Xu, Jing; Wang, Quan-de; Zhu, Quan; Fu, Ke-xiang; He, Fu-cheng; Li, Xiang-yuan
2010-06-01
The Stokes shift response function, which is related to the time dependent solvation energy, is calculated with the dielectric response function and a novel expression of nonequilibrium solvation energy. In the derivation, relationship between the polarization and the dielectric response function is used. With the dipole-in-a-sphere model applied to the system coumarin 343 and water as the solvent, encouraging agreement with the experimental data from Jimenez et al. is obtained [Nature 369, 471 (1994)].
Spectral methods for time dependent partial differential equations
Gottlieb, D.; Turkel, E.
1983-01-01
The theory of spectral methods for time dependent partial differential equations is reviewed. When the domain is periodic Fourier methods are presented while for nonperiodic problems both Chebyshev and Legendre methods are discussed. The theory is presented for both hyperbolic and parabolic systems using both Galerkin and collocation procedures. While most of the review considers problems with constant coefficients the extension to nonlinear problems is also discussed. Some results for problems with shocks are presented.
Time-dependent HF approach to SHE dynamics
Umar, A. S.; Oberacker, V. E.
2015-12-01
We employ the time-dependent Hartree-Fock (TDHF) method to study various aspects of the reactions utilized in searches for superheavy elements. These include capture cross-sections, quasifission, prediction of PCN, and other interesting dynamical quantities. We show that the microscopic TDHF approach provides an important tool to shed some light on the nuclear dynamics leading to the formation of superheavy elements.
Dose and time dependence of box jellyfish antivenom
2014-01-01
Background The effectiveness of the currently available box jellyfish (Chironex fleckeri) antivenom has been subject of debate for many years. To assess whether the box jellyfish antivenom has the ability to attenuate venom-induced damage at cellular level, the present study analyzed the dose and time dependence of the antivenom in a cell-based assay. Methods Different doses of antivenom were added to venom and subsequently administered to cells and the cell index was measured using xCelligen...
Krivoshapkin, Alexey L; Chikisheva, Tatiana A; Zubova, Alisa V; Kurbatov, Vladislav P; Titov, Anatoli T; Volkov, Pavel V
2014-11-01
To report the analysis of 3 cases of ancient trepanation discovered in the craniological collection (153 skulls) of the Pazyryk nomadic culture (500-300 bc) from the Gorny Altai, Russia, and to evaluate the technique, instrumentation, and materials used for cranial surgery as well as the motivation for the trepanations in Scythian times. A multidisciplinary approach was chosen to study the trepanned skulls. Visual inspection and examination under magnification, multislice computed tomography, high-field magnetic resonance imaging, and coupled plasma mass spectrometry and synchrotron radiation-induced x-ray fluorescence analysis of the bone samples from the site of trephination were used. In the Pazyryk culture, trepanation was very likely used to perform the intracranial procedures that were not yet indicated by Hippocrates. No signs of bone infection were detected. Higher copper abundance found at the site of trepanation showed that a bronze knife was the most likely tool used by Scythian surgeons. Our data suggest that the Scythian population of the Altai Mountains had sufficient medical knowledge to perform sophisticated and successful manipulations on the human skulls. Scraping technique with bronze tools was quite effective for prevention of wound infection and resulted in a high survival rate after surgery. In the era of methicillin-resistant Staphylococcus aureus, it may be useful to consider some ancient surgical technologies. Copyright © 2014 Elsevier Inc. All rights reserved.
Surgical hand disinfection with a propanol-based hand rub: equivalence of shorter application times.
Kampf, G; Ostermeyer, C; Heeg, P
2005-04-01
The aim of this study was to determine the efficacy of a propanol-based hand rub at application times shorter than 3 min. The bacterial pre-value was obtained from the finger tips (prEN 12791). Subjects treated their hands with the reference procedure (n-propanol, 60%) for 3 min or the product (crossover design). Sterillium was applied for 3, 2, 1.5 and 1 min. Four other preparations were tested for 1 min. Post-values (immediate effect) were taken from one hand, and the other hand was gloved for 3h. After the gloves were removed, the second post-value was taken (sustained effect). Sterillium was more effective than the reference procedure at 3, 2 and 1.5 min (immediate and sustained effect). The immediate effect after 1 min was significantly lower [mean log(10) reduction factor (RF): 1.91+/-0.90 vs. 2.52+/-0.95; P=0.001], whereas the sustained effect was not (mean RF: 1.81+/-1.06 vs. 2.05+/-1.14; P=0.204). All other preparations failed the efficacy requirement at 1 min for both the immediate and sustained effect. Using 2 x 3 mL Sterillium for a total of 1.5 min for surgical hand disinfection was at least as effective as the 3-min reference disinfection.
Time-dependent density-functional theory for extended systems
Energy Technology Data Exchange (ETDEWEB)
Botti, Silvana [European Theoretical Spectroscopy Facility (ETSF) (Country Unknown); Schindlmayr, Arno [European Theoretical Spectroscopy Facility (ETSF) (Country Unknown); Del Sole, Rodolfo [European Theoretical Spectroscopy Facility (ETSF) (Country Unknown); Reining, Lucia [European Theoretical Spectroscopy Facility (ETSF) (Country Unknown)
2007-03-15
For the calculation of neutral excitations, time-dependent density functional theory (TDDFT) is an exact reformulation of the many-body time-dependent Schroedinger equation, based on knowledge of the density instead of the many-body wavefunction. The density can be determined in an efficient scheme by solving one-particle non-interacting Schroedinger equations-the Kohn-Sham equations. The complication of the problem is hidden in the-unknown-time-dependent exchange and correlation potential that appears in the Kohn-Sham equations and for which it is essential to find good approximations. Many approximations have been suggested and tested for finite systems, where even the very simple adiabatic local-density approximation (ALDA) has often proved to be successful. In the case of solids, ALDA fails to reproduce optical absorption spectra, which are instead well described by solving the Bethe-Salpeter equation of many-body perturbation theory (MBPT). On the other hand, ALDA can lead to excellent results for loss functions (at vanishing and finite momentum transfer). In view of this and thanks to recent successful developments of improved linear-response kernels derived from MBPT, TDDFT is today considered a promising alternative to MBPT for the calculation of electronic spectra, even for solids. After reviewing the fundamentals of TDDFT within linear response, we discuss different approaches and a variety of applications to extended systems.
Time-dependent strains and stresses in a pumpkin balloon
Gerngross, T.; Xu, Y.; Pellegrino, S.
This paper presents a study of pumpkin-shaped superpressure balloons consisting of gores made from a thin polymeric film attached to high stiffness meridional tendons This type of design is being used for the NASA ULDB balloons The gore film shows considerable time-dependent stress relaxation whereas the behaviour of the tendons is essentially time-independent Upon inflation and pressurization the instantaneous i e linear-elastic strain and stress distributions in the film show significantly higher values in the meridional direction However over time and due to the biaxial visco-elastic stress relaxation of the the gore material the em hoop strains increase and the em meridional stresses decrease whereas the em remaining strain and stress components remain substantially unchanged These results are important for a correct assessment of the structural integrity of a pumpkin balloon in a long-duration mission both in terms of the material performance and the overall stability of the shape of the balloon An experimental investigation of the time dependence of the biaxial strain distribution in the film of a 4 m diameter 48 gore pumpkin balloon is presented The inflated shape of selected gores has been measured using photogrammetry and the time variation in strain components at some particular points of these gores has been measured under constant pressure and temperature The results show good correlation with a numerical study using the ABAQUS finite-element package that includes a widely used model of
Angular dependence of photoemission time delay in helium
Heuser, Sebastian; Jiménez Galán, Álvaro; Cirelli, Claudio; Marante, Carlos; Sabbar, Mazyar; Boge, Robert; Lucchini, Matteo; Gallmann, Lukas; Ivanov, Igor; Kheifets, Anatoli S.; Dahlström, J. Marcus; Lindroth, Eva; Argenti, Luca; Martín, Fernando; Keller, Ursula
2016-12-01
Time delays of electrons emitted from an isotropic initial state with the absorption of a single photon and leaving behind an isotropic ion are angle independent. Using an interferometric method involving XUV attosecond pulse trains and an IR-probe field in combination with a detection scheme, which allows for full three-dimensional momentum resolution, we show that measured time delays between electrons liberated from the 1 s2 spherically symmetric ground state of helium depend on the emission direction of the electrons relative to the common linear polarization axis of the ionizing XUV light and the IR-probing field. Such time delay anisotropy, for which we measure values as large as 60 as, is caused by the interplay between final quantum states with different symmetry and arises naturally whenever the photoionization process involves the exchange of more than one photon. With the support of accurate theoretical models, the angular dependence of the time delay is attributed to small phase differences that are induced in the laser-driven continuum transitions to the final states. Since most measurement techniques tracing attosecond electron dynamics involve the exchange of at least two photons, this is a general and significant effect that must be taken into account in all measurements of time delays involving photoionization processes.
Hamiltonian formulation of time-dependent plausible inference
Davis, Sergio
2014-01-01
Maximization of the path information entropy is a clear prescription for performing time-dependent plausible inference. Here it is shown that, following this prescription under the assumption of arbitrary instantaneous constraints on position and velocity, a Lagrangian emerges which determines the most probable trajectory. Deviations from the probability maximum can be consistently described as slices in time by a Hamiltonian, according to a nonlinear Langevin equation and its associated Fokker-Planck equation. The connections unveiled between the maximization of path entropy and the Langevin/Fokker-Planck equations imply that missing information about the phase space coordinate never decreases in time, a purely information-theoretical version of the Second Law of Thermodynamics. All of these results are independent of any physical assumptions, and thus valid for any generalized coordinate as a function of time, or any other parameter. This reinforces the view that the Second Law is a fundamental property of ...
Time-dependent density-functional description of nuclear dynamics
Nakatsukasa, Takashi; Matsuo, Masayuki; Yabana, Kazuhiro
2016-01-01
We present the basic concepts and recent developments in the time-dependent density functional theory (TDDFT) for describing nuclear dynamics at low energy. The symmetry breaking is inherent in nuclear energy density functionals (EDFs), which provides a practical description of important correlations at the ground state. Properties of elementary modes of excitation are strongly influenced by the symmetry breaking and can be studied with TDDFT. In particular, a number of recent developments in the linear response calculation have demonstrated their usefulness in description of collective modes of excitation in nuclei. Unrestricted real-time calculations have also become available in recent years, with new developments for quantitative description of nuclear collision phenomena. There are, however, limitations in the real-time approach; for instance, it cannot describe the many-body quantum tunneling. Thus, we treat the quantum fluctuations associated with slow collective motions assuming that time evolution of...
Histogram bin width selection for time-dependent Poisson processes
Energy Technology Data Exchange (ETDEWEB)
Koyama, Shinsuke; Shinomoto, Shigeru [Department of Physics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan)
2004-07-23
In constructing a time histogram of the event sequences derived from a nonstationary point process, we wish to determine the bin width such that the mean squared error of the histogram from the underlying rate of occurrence is minimized. We find that the optimal bin widths obtained for a doubly stochastic Poisson process and a sinusoidally regulated Poisson process exhibit different scaling relations with respect to the number of sequences, time scale and amplitude of rate modulation, but both diverge under similar parametric conditions. This implies that under these conditions, no determination of the time-dependent rate can be made. We also apply the kernel method to these point processes, and find that the optimal kernels do not exhibit any critical phenomena, unlike the time histogram method.
Histogram bin width selection for time-dependent Poisson processes
Koyama, Shinsuke; Shinomoto, Shigeru
2004-07-01
In constructing a time histogram of the event sequences derived from a nonstationary point process, we wish to determine the bin width such that the mean squared error of the histogram from the underlying rate of occurrence is minimized. We find that the optimal bin widths obtained for a doubly stochastic Poisson process and a sinusoidally regulated Poisson process exhibit different scaling relations with respect to the number of sequences, time scale and amplitude of rate modulation, but both diverge under similar parametric conditions. This implies that under these conditions, no determination of the time-dependent rate can be made. We also apply the kernel method to these point processes, and find that the optimal kernels do not exhibit any critical phenomena, unlike the time histogram method.
Characterization of Models for Time-Dependent Behavior of Soils
DEFF Research Database (Denmark)
Liingaard, Morten; Augustesen, Anders; Lade, Poul V.
2004-01-01
Different classes of constitutive models have been developed to capture the time-dependent viscous phenomena ~ creep, stress relaxation, and rate effects ! observed in soils. Models based on empirical, rheological, and general stress-strain-time concepts have been studied. The first part...... is a review of the empirical relations, which apply only to problems of specific boundary conditions and frequently involve natural time alone. The second part deals with different rheological models used for describing the viscous effects in the field of solid mechanics. The rheological models are typically...... developed for metals and steel but are, to some extent, used to characterize time effects in geomaterials. The third part is a review of constitutive laws that describe not only viscous effects but also the inviscid ( rate-independent) behavior of soils, in principle, under any possible loading condition...
Predicting Sequences of Progressive Events Times with Time-dependent Covariates
Cai, Song; Newlands, Nathaniel
2010-01-01
This paper presents an approach to modeling progressive event-history data when the overall objective is prediction based on time-dependent covariates. This approach does not model the hazard function directly. Instead, it models the process of the state indicators of the event history so that the time-dependent covariates can be incorporated and predictors of the future events easily formulated. Our model can be applied to a range of real-world problems in medical and agricultural science.
Estimation of eighth costal cartilage in surgical timing of microtia reconstruction.
Moon, Il Yung; Oh, Kap Sung; Lim, So Young; Pyon, Jai-Kyong; Mun, Goo-Hyun; Bang, Sa-Ik
2015-01-01
There is controversy over the optimal timing of microtia reconstruction. The eighth costal cartilage, which is used to shape the helix framework, can be one of the key factors determining surgical timing of microtia reconstruction. Nevertheless, it is difficult to predict the length of the eighth costal cartilage preoperatively. The aim of the present study was to suggest clinical predictors of the length of the eighth cartilage by assessing the correlation between the actual length of the eighth cartilage and preoperative measurements of the cartilage length using three-dimensional rib-cage computed tomography (3D rib-cage CT). A retrospective analysis was performed on a total of 97 patients who underwent preoperative 3D rib-cage CT and auricular reconstruction using a rib cartilage graft between January 2010 and February 2013. The length of the eighth costal cartilage on 3D rib-cage CT was measured preoperatively, and the length of the harvested eighth rib cartilage was measured intraoperatively. We analyzed the association between the preoperative and intraoperative measured length of the eighth rib, with patient age, height, weight, and body mass index. Preoperative measurement using 3D rib-cage CT showed a high correlation with actual cartilage length. Height and weight correlated more strongly with length than with age. This study describes the usefulness of 3D rib-cage CT for preoperative measurement of the length of the eighth costal cartilage. The measurement of the eighth rib cartilage on 3D rib-cage CT could be a useful aid for reconstructive surgeons in planning microtia reconstruction.
Toward real-time endoscopically-guided robotic navigation based on a 3D virtual surgical field model
Gong, Yuanzheng; Hu, Danying; Hannaford, Blake; Seibel, Eric J.
2015-03-01
The challenge is to accurately guide the surgical tool within the three-dimensional (3D) surgical field for roboticallyassisted operations such as tumor margin removal from a debulked brain tumor cavity. The proposed technique is 3D image-guided surgical navigation based on matching intraoperative video frames to a 3D virtual model of the surgical field. A small laser-scanning endoscopic camera was attached to a mock minimally-invasive surgical tool that was manipulated toward a region of interest (residual tumor) within a phantom of a debulked brain tumor. Video frames from the endoscope provided features that were matched to the 3D virtual model, which were reconstructed earlier by raster scanning over the surgical field. Camera pose (position and orientation) is recovered by implementing a constrained bundle adjustment algorithm. Navigational error during the approach to fluorescence target (residual tumor) is determined by comparing the calculated camera pose to the measured camera pose using a micro-positioning stage. From these preliminary results, computation efficiency of the algorithm in MATLAB code is near real-time (2.5 sec for each estimation of pose), which can be improved by implementation in C++. Error analysis produced 3-mm distance error and 2.5 degree of orientation error on average. The sources of these errors come from 1) inaccuracy of the 3D virtual model, generated on a calibrated RAVEN robotic platform with stereo tracking; 2) inaccuracy of endoscope intrinsic parameters, such as focal length; and 3) any endoscopic image distortion from scanning irregularities. This work demonstrates feasibility of micro-camera 3D guidance of a robotic surgical tool.
Time-dependent switched discrete-time linear systems control and filtering
Zhang, Lixian; Shi, Peng; Lu, Qiugang
2016-01-01
This book focuses on the basic control and filtering synthesis problems for discrete-time switched linear systems under time-dependent switching signals. Chapter 1, as an introduction of the book, gives the backgrounds and motivations of switched systems, the definitions of the typical time-dependent switching signals, the differences and links to other types of systems with hybrid characteristics and a literature review mainly on the control and filtering for the underlying systems. By summarizing the multiple Lyapunov-like functions (MLFs) approach in which different requirements on comparisons of Lyapunov function values at switching instants, a series of methodologies are developed for the issues on stability and stabilization, and l2-gain performance or tube-based robustness for l∞ disturbance, respectively, in Chapters 2 and 3. Chapters 4 and 5 are devoted to the control and filtering problems for the time-dependent switched linear systems with either polytopic uncertainties or measurable time-varying...
Quasi-real-time fluorescence imaging with lifetime dependent contrast
Jiang, Pei-Chi; Grundfest, Warren S.; Stafsudd, Oscar M.
2011-08-01
Conventional fluorescence lifetime imaging requires complicated algorithms to extract lifetimes of fluorophores and acquisition of multiple data points at progressively longer delay times to characterize tissues. To address diminishing signal-to-noise ratios at these progressively longer time delays, we report a time-resolved fluorescence imaging method, normalized fluorescence yield imaging that does not require the extraction of lifetimes. The concept is to extract the ``contrast'' instead of the lifetime value of the fluorophores by using simple mathematical algorithms. This process converts differences in decay times directly to different intensities. The technique was verified experimentally using a gated iCCD camera and an ultraviolet light-emitting diode light source. It was shown that this method can distinguish between chemical dyes (Fluorescein and Rhodamine-B) and biomedical samples, such as powders of elastin and collagen. Good contrast was obtained between fluorophores that varied by less than 6% in lifetime. Additionally, it was shown that long gate times up to 16 ns achieve good contrast depending upon the samples to be studied. These results support the feasibility of time-resolved fluorescence imaging without lifetime extraction, which has a potential clinical role in noninvasive real-time imaging.
Hot Jupiter Breezes: Time-dependent Outflows from Extrasolar Planets
Owen, James E
2015-01-01
We explore the dynamics of magnetically controlled outflows from Hot Jupiters, where these flows are driven by UV heating from the central star. In these systems, some of the open field lines do not allow the flow to pass smoothly through the sonic point, so that steady-state solutions do not exist in general. This paper focuses on this type of magnetic field configuration, where the resulting flow becomes manifestly time-dependent. We consider the case of both steady heating and time-variable heating, and find the time scales for the corresponding time variations of the outflow. Because the flow cannot pass through the sonic transition, it remains subsonic and leads to so-called breeze solutions. One manifestation of the time variability is that the flow samples a collection of different breeze solutions over time, and the mass outflow rate varies in quasi-periodic fashion. Because the flow is subsonic, information can propagate inward from the outer boundary, which determines, in part, the time scale of the...
Characterizing time-dependent mechanics in metallic MEMS
Directory of Open Access Journals (Sweden)
Geers M.G.D.
2010-06-01
Full Text Available Experiments for characterization of time-dependent material properties in free-standing metallic microelectromechanical system (MEMS pose challenges: e.g. fabrication and handling (sub-μm sized specimens, control and measurement of sub-μN loads and sub-μm displacements over long periods and various temperatures [1]. A variety of experimental setups have been reported each having their pros and cons. One example is a micro-tensile tester with an ingenious electro-static specimen gripping system [2] aiding simple specimen design giving good results at μN and sub-μm levels, but without in-situ full-field observations. Other progressive examples assimilate the specimen, MEMS actuators and load cells on a single chip [3,4] yielding significant results at nN and nm levels with in-situ TEM/SEM observability, though not without complications: complex load actuator/sensor calibration per chip, measures to reduce fabrication failure and unfeasible cofabrication on wafers with commercial metallic MEMS. This work aims to overcome these drawbacks by developing experimental methods with high sensitivity, precision and in-situ full-field observation capabilities. Moreover, these should be applicable to simple free-standing metallic MEMS that can be co-fabricated with commercial devices. These methods will then serve in systematic studies into size-effects in time-dependent material properties. First a numeric-experimental method is developed. It characterizes bending deformation of onwafer μm-sized aluminum cantilevers. A specially designed micro-clamp is used to mechanically apply a constant precise deflection of the beam (zres <50 nm for a prolonged period, see fig. 1. After this period, the deflection by the micro-clamp is removed. Full-field height maps with the ensuing deformation are measured over time with confocal optical profilometry (COP. This yields the tip deflection as function of time with ~3 nm precision, see fig.2. To extract material
Passive microrheology in the effective time domain: analyzing time dependent colloidal dispersions.
Vyas, Bhavna M; Orpe, Ashish V; Kaushal, Manish; Joshi, Yogesh M
2016-10-21
We studied the aging dynamics of an aqueous suspension of LAPONITE®, a model time dependent soft glassy material, using a passive microrheology technique. This system is known to undergo physical aging during which its microstructure evolves progressively to explore lower free energy states. Optical microscopy is used to monitor the motion of micron-sized tracer probes embedded in a sample kept between two glass plates. The mean square displacements (MSD) obtained from the motion of the tracer particles show a systematic change from a purely diffusive behavior at short aging times to a subdiffusive behavior as the material ages. Interestingly, the MSDs at all the aging times as well as different LAPONITE® concentrations superpose remarkably to show a time-aging time master curve when the system is transformed from the real time domain to the effective time domain, which is obtained by rescaling the material clock to account for the age dependent relaxation time. The transformation of the master curve from the effective time domain to the real time domain leads to the prediction of the MSD in real time over a span of 5 decades when the measured data at individual aging times are only over 2 decades. Since the MSD obtained from microrheology is proportional to the creep compliance of a material, by using the Boltzmann superposition principle along with the convolution relation in the effective time domain, we predict the stress relaxation behavior of the system in real time. This work shows that the effective time approach applied to microrheology facilitates the prediction of long time creep and relaxation dynamics of a time dependent soft material by carrying out short time experiments at different aging times.
Modeling of time dependent subsidence for coal and ore deposits
Institute of Scientific and Technical Information of China (English)
Ryszard Hejmanowski
2015-01-01
Coal and ore underground mining generates subsidence and deformation of the land surface. Those defor-mations may cause damage to buildings and infrastructures. The environmental impact of subsidence will not be accepted in the future by the society in many countries. Especially there, where the mining regions are densely urbanized, the acceptance of the ground deformations decreases every year. The only solution is to limit the subsidence or its impact on the infrastructure. The first is not rentable for the mining industry, the second depends on the precise subsidence prediction and good preventing management involved in the mining areas. The precision of the subsidence prediction depends strictly on the mathematical model of the deformation phenomenon and on the uncertainty of the input data. The subsidence prediction in the geological conditions of the raw materials used to be made on the basis of numerical modeling or the stochastic models. A modified solution of the stochastic model by Knothe will be presented in the paper. The author focuses on the precise description of the deposit shape and on the time dependent displacements of the rock mass. A two parameters’ time function has been introduced in the algorithm.
Time-Dependent Neutron and Photon Dose-Field Analysis
Energy Technology Data Exchange (ETDEWEB)
Wooten, Hasani Omar [Georgia Inst. of Technology, Atlanta, GA (United States)
2005-08-01
A unique tool is developed that allows the user to model physical representations of complicated glovebox facilities in two dimensions and determine neutral-particle flux and ambient dose-equivalent fields throughout that geometry. The Pandemonium code, originally designed to determine flux and dose-rates only, is improved to include realistic glovebox geometries, time-dependent source and detector positions, time-dependent shielding thickness calculations, time-integrated doses, a representative criticality accident scenario based on time-dependent reactor kinetics, and more rigorous photon treatment. A primary benefit of this work has been an extensive analysis and improvement of the photon model that is not limited to the application described in this thesis. The photon model has been extended in energy range to 10 MeV to include photons from fission and new photon buildup factors have been included that account for the effects of photon buildup at slant-path thicknesses as a function of angle, where the mean free path thickness has been preserved. The overall system of codes is user-friendly and it is directly applicable to facilities such as the plutonium facility at Los Alamos National Laboratory, where high-intensity neutron and photon emitters are regularly used. The codes may be used to determine a priori doses for given work scenarios in an effort to supply dose information to process models which will in turn assist decision makers on ensuring as low as reasonably achievable (ALARA) compliance. In addition, coupling the computational results of these tools with the process model visualization tools will help to increase worker safety and radiological safety awareness.
Relating Time-Dependent Acceleration and Height Using an Elevator
Kinser, Jason M.
2015-04-01
A simple experiment in relating a time-dependent linear acceleration function to height is explored through the use of a smartphone and an elevator. Given acceleration as a function of time1, a(t), the velocity function and position functions are determined through integration as in v (t ) =∫ a (t ) d t (1) and x (t ) =∫ v (t ) dt. Mobile devices such as smartphones or tablets have accelerometers that capture slowly evolving acceleration with respect to time and can deliver those measurements as a CSV file. A recent example measured the oscillations of the elevator as it starts its motion.2 In the application presented here the mobile device is used to estimate the height of the elevator ride. By estimating the functional form of the acceleration of an elevator ride, it is possible to estimate the height of the ride through Eqs. (1) and (2).
Hybrid Approach for the Public Transportation Time Dependent Orienteering Problem with Time Windows
Garcia, Ander; Arbelaitz, Olatz; Vansteenwegen, Pieter; Souffriau, Wouter; Linaza, Maria Teresa
The Time Dependent Orienteering Problem with Time Windows (TDOPTW) consists of a set of locations with associated time windows and scores. Visiting a location allows to collect its score as a reward. Traveling time between locations varies depending on the leave time. The objective is to obtain a route that maximizes the obtained score within a limited amount of time. In this paper we target the use of public transportation in a city, where users may move on foot or by public transportation. The approach can also be applied to the logistic sector, for example to the multimodal freight transportation. We apply an hybrid approach to tackle the problem. Experimental results for the city of San Sebastian show we are able to obtain valid routes in real-time.
Hassan, Mohammad Khaled
2016-01-01
Bias Temperature Instability (BTI) is a major reliability concern in CMOS technology, especially with High dielectric constant (High-\\k{appa}/HK) metal gate (MG) transistors. In addition, the time independent process induced variation has also increased because of the aggressive scaling down of devices. As a result, the faster devices at the lower threshold voltage distribution tail experience higher stress, leading to additional skewness in the BTI degradation. Since time dependent dielectric breakdown (TDDB) and stress-induced leakage current (SILC) in NMOS devices are correlated to BTI, it is necessary to investigate the effect of time zero variability on all these effects simultaneously. To that effect, we propose a simulation framework to model and analyze the impact of time-zero variability (in particular, random dopant fluctuations) on different aging effects. For small area devices (~1000 nm2) in 30nm technology, we observe significant effect of Random Dopant Fluctuation (RDF) on BTI induced variabili...
Effects of Temperature on Time Dependent Rheological Characteristics of Koumiss
Directory of Open Access Journals (Sweden)
Serdal Sabancı
2016-04-01
Full Text Available The rheological properties of koumiss were investigated at different temperatures (4, 10, and 20°C. Experimental shear stress–shear rate data were fitted to different rheological models. The consistency of koumiss was predicted by using the power-law model since it described the consistency of koumiss best with highest regression coefficient and lowest errors (root mean square error and chi-square. Koumiss exhibited shear thinning behavior (n<1. The flow activation energy for temperature dependency of consistency was 25.532 kJ/mol, and the frequency constant was 2.18×10-7Pa.sn. As the temperature increased the time dependent thixotropic characteristics of koumiss decreased.
Dependency Structures in Differentially Coded Cardiovascular Time Series
Directory of Open Access Journals (Sweden)
Tatjana Tasic
2017-01-01
Full Text Available Objectives. This paper analyses temporal dependency in the time series recorded from aging rats, the healthy ones and those with early developed hypertension. The aim is to explore effects of age and hypertension on mutual sample relationship along the time axis. Methods. A copula method is applied to raw and to differentially coded signals. The latter ones were additionally binary encoded for a joint conditional entropy application. The signals were recorded from freely moving male Wistar rats and from spontaneous hypertensive rats, aged 3 months and 12 months. Results. The highest level of comonotonic behavior of pulse interval with respect to systolic blood pressure is observed at time lags τ=0, 3, and 4, while a strong counter-monotonic behavior occurs at time lags τ=1 and 2. Conclusion. Dynamic range of aging rats is considerably reduced in hypertensive groups. Conditional entropy of systolic blood pressure signal, compared to unconditional, shows an increased level of discrepancy, except for a time lag 1, where the equality is preserved in spite of the memory of differential coder. The antiparallel streams play an important role at single beat time lag.
Dependency Structures in Differentially Coded Cardiovascular Time Series
Tasic, Tatjana; Jovanovic, Sladjana; Mohamoud, Omer; Skoric, Tamara; Japundzic-Zigon, Nina
2017-01-01
Objectives. This paper analyses temporal dependency in the time series recorded from aging rats, the healthy ones and those with early developed hypertension. The aim is to explore effects of age and hypertension on mutual sample relationship along the time axis. Methods. A copula method is applied to raw and to differentially coded signals. The latter ones were additionally binary encoded for a joint conditional entropy application. The signals were recorded from freely moving male Wistar rats and from spontaneous hypertensive rats, aged 3 months and 12 months. Results. The highest level of comonotonic behavior of pulse interval with respect to systolic blood pressure is observed at time lags τ = 0, 3, and 4, while a strong counter-monotonic behavior occurs at time lags τ = 1 and 2. Conclusion. Dynamic range of aging rats is considerably reduced in hypertensive groups. Conditional entropy of systolic blood pressure signal, compared to unconditional, shows an increased level of discrepancy, except for a time lag 1, where the equality is preserved in spite of the memory of differential coder. The antiparallel streams play an important role at single beat time lag. PMID:28127384
Dependency Structures in Differentially Coded Cardiovascular Time Series.
Tasic, Tatjana; Jovanovic, Sladjana; Mohamoud, Omer; Skoric, Tamara; Japundzic-Zigon, Nina; Bajic, Dragana
2017-01-01
Objectives. This paper analyses temporal dependency in the time series recorded from aging rats, the healthy ones and those with early developed hypertension. The aim is to explore effects of age and hypertension on mutual sample relationship along the time axis. Methods. A copula method is applied to raw and to differentially coded signals. The latter ones were additionally binary encoded for a joint conditional entropy application. The signals were recorded from freely moving male Wistar rats and from spontaneous hypertensive rats, aged 3 months and 12 months. Results. The highest level of comonotonic behavior of pulse interval with respect to systolic blood pressure is observed at time lags τ = 0, 3, and 4, while a strong counter-monotonic behavior occurs at time lags τ = 1 and 2. Conclusion. Dynamic range of aging rats is considerably reduced in hypertensive groups. Conditional entropy of systolic blood pressure signal, compared to unconditional, shows an increased level of discrepancy, except for a time lag 1, where the equality is preserved in spite of the memory of differential coder. The antiparallel streams play an important role at single beat time lag.
Time-adaptive and history-adaptive multicriterion routing in stochastic, time-dependent networks
DEFF Research Database (Denmark)
Pretolani, Daniele; Nielsen, Lars Relund; Andersen, Kim Allan
2009-01-01
We compare two different models for multicriterion routing in stochastic time-dependent networks: the classic "time-adaptive'' model and the more flexible "history-adaptive'' one. We point out several properties of the sets of efficient solutions found under the two models. We also devise a metho...
Characterization of time-dependent anelastic microbeam bending mechanics
Bergers, L. I. J. C.; Hoefnagels, J. P. M.; Geers, M. G. D.
2014-09-01
This paper presents an accurate yet straightforward methodology for characterizing time-dependent anelastic mechanics of thin metal films employed in metalic microelectromechanical systems (MEMS). The deflection of microbeams is controlled with a mechanical micro-clamp, measured with digital holographic microscopy and processed with global digital image correlation (GDIC). The GDIC processing directly incorporates kinematics into the three-dimensional correlation problem, describing drift-induced rigid body motion and the beam deflection. This yields beam curvature measurements with a resolution of <1.5 × 10-6 µm-1, or for films thinner than 5 µm, a strain resolution of <4 μɛ. Using a simple experimental sequence, these curvature measurements are then combined with a linear multi-mode time-dependent anelastic model and a priori knowledge of the Young's modulus. This allows the characterization of the material behaviour in the absence of an additional explicit force measurement, which simplifies the experimental setup. Using this methodology we characterize the anelasticity of 5 µm-thick Al(1 wt%)-Cu microbeams of varying microstructures over relevant timescales of 1 to 1 × 105 s and adequately predict the time and amplitude response of experiments performed for various loading conditions. This demonstrates the validity of the methodology and the suitability for thin film mechanics research for MEMS development.
Distributed energy storage: Time-dependent tree flow design
Bejan, A.; Ziaei, S.; Lorente, S.
2016-05-01
This article proposes "distributed energy storage" as a basic design problem of distributing energy storage material on an area. The energy flows by fluid flow from a concentrated source to points (users) distributed equidistantly on the area. The flow is time-dependent. Several scenarios are analyzed: sensible-heat storage, latent-heat storage, exergy storage vs energy storage, and the distribution of a finite supply of heat transfer surface between the source fluid and the distributed storage material. The chief conclusion is that the finite amount of storage material should be distributed proportionally with the distribution of the flow rate of heating agent arriving on the area. The total time needed by the source stream to "invade" the area is cumulative (the sum of the storage times required at each storage site) and depends on the energy distribution paths and the sequence in which the users are served by the source stream. Directions for future designs of distributed storage and retrieval are outlined in the concluding section.
Perspective: Fundamental aspects of time-dependent density functional theory
Maitra, Neepa T.
2016-06-01
In the thirty-two years since the birth of the foundational theorems, time-dependent density functional theory has had a tremendous impact on calculations of electronic spectra and dynamics in chemistry, biology, solid-state physics, and materials science. Alongside the wide-ranging applications, there has been much progress in understanding fundamental aspects of the functionals and the theory itself. This Perspective looks back to some of these developments, reports on some recent progress and current challenges for functionals, and speculates on future directions to improve the accuracy of approximations used in this relatively young theory.
Density-functional perturbation theory goes time-dependent
Gebauer, Ralph; Rocca, Dario; Baroni, Stefano
2009-01-01
The scope of time-dependent density-functional theory (TDDFT) is limited to the lowest portion of the spectrum of rather small systems (a few tens of atoms at most). In the static regime, density-functional perturbation theory (DFPT) allows one to calculate response functions of systems as large as currently dealt with in ground-state simulations. In this paper we present an effective way of combining DFPT with TDDFT. The dynamical polarizability is first expressed as an off-diagonal matrix e...
Time-dependent models of dense PDRs with complex molecules
Morata, O.; Herbst, E.
2008-01-01
We present a study of the chemistry of a dense photon-dominated region (PDR) using a time-dependent chemical model. Our major interest is to study the spatial distribution of complex molecules such as hydrocarbons and cyanopolyynes in the cool dense material bordering regions where star formation has taken place. Our standard model uses a homogeneous cloud of density 2x10e4 cm-3 and temperature T=40 K, which is irradiated by a far-ultraviolet radiation field of intermediate intensity, given b...
Quantifying Time Dependent Moisture Storage and Transport Properties
DEFF Research Database (Denmark)
Peuhkuri, Ruut H
2003-01-01
This paper describes an experimental and numerical approach to quantify the time dependence of sorption mechanisms for some hygroscopic building - mostly insulation - materials. Some investigations of retarded sorption and non-Fickian phenomena, mostly on wood, have given inspiration to the present...... analysis on these other materials. The true moisture capacity of a material can not be described by the slope of the sorption isotherms alone, when the material is exposed to dynamic changes in the moisture conditions. Still, the assumption of an immediate equilibrium is well accepted in the simulation...
Time-dependent Integrated Predictive Modeling of ITER Plasmas
Institute of Scientific and Technical Information of China (English)
R.V. Budny
2007-01-01
@@ Introduction Modeling burning plasmas is important for speeding progress toward practical Tokamak energy production. Examples of issues that can be elucidated by modelinginclude requirements for heating, fueling, torque, and current drive systems, design of diagnostics, and estimates of the plasma performance (e.g., fusion power production) in various plasma scenarios. The modeling should be time-dependent to demonstrate that burning plasmas can be created, maintained (controlled), and terminated successfully. The modeling also should be integrated to treat self-consistently the nonlinearities and strong coupling between the plasma, heating, current drive, confinement, and control systems.
Time-Dependent Mean-Field Games with Logarithmic Nonlinearities
Gomes, Diogo A.
2015-10-06
In this paper, we prove the existence of classical solutions for time-dependent mean-field games with a logarithmic nonlinearity and subquadratic Hamiltonians. Because the logarithm is unbounded from below, this nonlinearity poses substantial mathematical challenges that have not been addressed in the literature. Our result is proven by recurring to a delicate argument which combines Lipschitz regularity for the Hamilton-Jacobi equation with estimates for the nonlinearity in suitable Lebesgue spaces. Lipschitz estimates follow from an application of the nonlinear adjoint method. These are then combined with a priori bounds for solutions of the Fokker-Planck equation and a concavity argument for the nonlinearity.
Time-dependent density-functional theory concepts and applications
Ullrich, Carsten A
2011-01-01
Time-dependent density-functional theory (TDDFT) describes the quantum dynamics of interacting electronic many-body systems formally exactly and in a practical and efficient manner. TDDFT has become the leading method for calculating excitation energies and optical properties of large molecules, with accuracies that rival traditional wave-function based methods, but at a fraction of the computational cost.This book is the first graduate-level text on the concepts and applications of TDDFT, including many examples and exercises, and extensive coverage of the literature. The book begins with a s
Efficient auxiliary-mode approach for time-dependent nanoelectronics
Popescu, Bogdan Stefan; Croy, Alexander
2016-09-01
A new scheme for numerically solving the equations arising in the time-dependent non-equilibrium Green's function formalism is developed. It is based on an auxiliary-mode expansion of the self-energies which convert the complicated set of integro-differential equations into a set of ordinary differential equations. In the new scheme all auxiliary matrices are replaced by vectors or scalars. This drastically reduces the computational effort and memory requirements of the method, rendering it applicable to topical problems in electron quantum optics and molecular electronics. As an illustrative example we consider the dynamics of a Leviton wave-packet in a 1D wire.
Optimal moving grids for time-dependent partial differential equations
Wathen, A. J.
1992-01-01
Various adaptive moving grid techniques for the numerical solution of time-dependent partial differential equations were proposed. The precise criterion for grid motion varies, but most techniques will attempt to give grids on which the solution of the partial differential equation can be well represented. Moving grids are investigated on which the solutions of the linear heat conduction and viscous Burgers' equation in one space dimension are optimally approximated. Precisely, the results of numerical calculations of optimal moving grids for piecewise linear finite element approximation of PDE solutions in the least-squares norm are reported.
Time-dependent asymmetries in Bs decays at LHCb
Blouw, Johan
2007-01-01
The LHCb experiment will search for New Physics in Bs mixing. The Bs mixing phase will be extracted from the measurement of the time-dependent CP asymmetry in exclusive Bs decays governed by the $b \\to c\\bar{c}s$ quark level transition. Large New Physics effects can be discovered or excluded with the data collected during the very first physics run of LHC. Based on Monte Carlo simulations of the LHCb detector, the expected sensitivity with 2 fb$^{-1}$ on the CP-violation parameter $\\phi_s$, is $\\sigma(\\phi_s)$ = 0.022.
Dirac equation on coordinate dependent noncommutative space–time
Energy Technology Data Exchange (ETDEWEB)
Kupriyanov, V.G., E-mail: vladislav.kupriyanov@gmail.com
2014-05-01
In this paper we discuss classical aspects of spinor field theory on the coordinate dependent noncommutative space–time. The noncommutative Dirac equation describing spinning particle in an external vector field and the corresponding action principle are proposed. The specific choice of a star product allows us to derive a conserved noncommutative probability current and to obtain the energy–momentum tensor for free noncommutative spinor field. Finally, we consider a free noncommutative Dirac fermion and show that if the Poisson structure is Lorentz-covariant, the standard energy–momentum dispersion relation remains valid.
Dirac equation on coordinate dependent noncommutative space-time
Kupriyanov, V. G.
2014-05-01
In this paper we discuss classical aspects of spinor field theory on the coordinate dependent noncommutative space-time. The noncommutative Dirac equation describing spinning particle in an external vector field and the corresponding action principle are proposed. The specific choice of a star product allows us to derive a conserved noncommutative probability current and to obtain the energy-momentum tensor for free noncommutative spinor field. Finally, we consider a free noncommutative Dirac fermion and show that if the Poisson structure is Lorentz-covariant, the standard energy-momentum dispersion relation remains valid.
The surgical management of male breast cancer: Time for an easy access national reporting database?
Directory of Open Access Journals (Sweden)
Robert M.T. Staruch
2016-08-01
Discussion: We report a series of seven cases of male breast cancer encountered over three years, evaluating patient demographics as well as treatment and outcomes. In our series patients were managed with mastectomy. New evidence is questioning the role of mastectomy against breast conserving surgery in male patients. Furthermore there is a lack of reporting infrastructure for national data capture of the benefits of surgical modalities. Literature review highlights the varied clinical experience between units that remains reported as podium presentation but not published. The establishment of an online international reporting registry would allow for efficient analysis of surgical outcomes to improve patient care from smaller single centres. This would facilitate large scale meta analysis by larger academic surgical centres.
Time Dependent \\hat{q} from AdS/CFT
Horowitz, W. A.
2017-07-01
We present the first ever AdS/CFT calculation of \\hat{q} for a light quark jet as a function of position or, equivalently, time. Our result does not suffer from the gamma factor blow up of the usual time-independent AdS/CFT heavy quark setup and is qualitatively similar to, but about a factor of 2/3 larger than, the light flavor result from Liu, Rajagopal, and Wiedemann. Our findings can be immediately implemented into any \\hat{q}-based energy loss model. Our \\hat{q} derivation relies on our calculation of the average distance squared, s 2(t), travelled by the endpoint of a string falling in an AdS3-Schwarzschild spacetime. The early time behavior is ballistic, s 2(t) ∼ t 2, but the late time behavior is the usual diffusive Brownian motion, s 2(t) ∼ t. These late time dynamics are universal and depend only on the near-horizon physics, which allows us to generalize our results to arbitrary dimensions and thus make contact with the physics explored by RHIC and LHC. Additionally, we find that AdS/CFT predicts angular ordering for radiation in a medium, just as in vacuum, and in contradistinction to weak-coupling. Finally, our results also imply, sensibly, that AdS/CFT predicts a smooth interpolation between the angular correlations of open heavy flavor and light flavor observables.
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.
Sanders, David S; Read-Brown, Sarah; Tu, Daniel C; Lambert, William E; Choi, Dongseok; Almario, Bella M; Yackel, Thomas R; Brown, Anna S; Chiang, Michael F
2014-05-01
Although electronic health record (EHR) systems have potential benefits, such as improved safety and quality of care, most ophthalmology practices in the United States have not adopted these systems. Concerns persist regarding potential negative impacts on clinical workflow. In particular, the impact of EHR operating room (OR) management systems on clinical efficiency in the ophthalmic surgery setting is unknown. To determine the impact of an EHR OR management system on intraoperative nursing documentation time, surgical volume, and staffing requirements. For documentation time and circulating nurses per procedure, a prospective cohort design was used between January 10, 2012, and January 10, 2013. For surgical volume and overall staffing requirements, a case series design was used between January 29, 2011, and January 28, 2013. This study involved ophthalmic OR nurses (n = 13) and surgeons (n = 25) at an academic medical center. Electronic health record OR management system implementation. (1) Documentation time (percentage of operating time documenting [POTD], absolute documentation time in minutes), (2) surgical volume (procedures/time), and (3) staffing requirements (full-time equivalents, circulating nurses/procedure). Outcomes were measured during a baseline period when paper documentation was used and during the early (first 3 months) and late (4-12 months) periods after EHR implementation. There was a worsening in total POTD in the early EHR period (83%) vs paper baseline (41%) (P system implementation was associated with worsening of intraoperative nursing documentation time especially in shorter procedures. However, it is possible to implement an EHR OR management system without serious negative impacts on surgical volume and staffing requirements.
Nuclear inertia from the time dependent pairing equations
Mirea, M.
2016-10-01
In a dynamical system, the momenta of inertia and the effective masses are not adiabatic quantities, but are dynamical ones that depend on the dissipated energy accumulated during motion. However, these parameters are calculated for adiabatic nuclear systems, leaving no room for dissipated energy. In this work, a formalism is elaborated in order to derive simultaneously the nuclear momenta of inertia and the effective masses by taking into account the appearance of dissipated energy for large amplitude motion of the nuclear system. The expressions that define the inertia are obtained from the variational principle. The same principle manages the time dependent pairing equations, offering estimations of the averaged dissipation energy for large amplitude motions. The model is applied to 232Th fission. The fission barrier was calculated along the least action trajectory. The dissipation energy, effective mass and moment of inertia are determined for different values of the collective velocities. The dissipation increases with the internuclear velocity in binary disintegration processes and modifies the effective mass parameters. We observed that the inertia decreases as long as the collective velocity increases to some moderate values and begins to grow for larger collective velocities. So, a dependence between the cranking mass parameters and the intrinsic excitation energy is evidenced. In order to investigate the overall effect, the half-lives are predicted for adiabatic and dynamics simulations.
Time-Dependent Tomographic Reconstruction of the Solar Corona
Vibert, Didier; Lamy, Philippe; Frazin, Richard A; Wojak, Julien
2016-01-01
Solar rotational tomography (SRT) applied to white-light coronal images observed at multiple aspect angles has been the preferred approach for determining the three-dimensional (3D) electron density structure of the solar corona. However, it is seriously hampered by the restrictive assumption that the corona is time-invariant which introduces significant errors in the reconstruction. We first explore several methods to mitigate the temporal variation of the corona by decoupling the "fast-varying" inner corona from the "slow-moving" outer corona using multiple masking (either by juxtaposition or recursive combination) and radial weighting. Weighting with a radial exponential profile provides some improvement over a classical reconstruction but only beyond 3 Rsun. We next consider a full time-dependent tomographic reconstruction involving spatio-temporal regularization and further introduce a co-rotating regularization aimed at preventing concentration of reconstructed density in the plane of the sky. Crucial t...
Goal Directed Relative Skyline Queries in Time Dependent Road Networks
Iyer, K B Priya
2012-01-01
The Wireless GIS technology is progressing rapidly in the area of mobile communications. Location-based spatial queries are becoming an integral part of many new mobile applications. The Skyline queries are latest apps under Location-based services. In this paper we introduce Goal Directed Relative Skyline queries on Time dependent (GD-RST) road networks. The algorithm uses travel time as a metric in finding the data object by considering multiple query points (multi-source skyline) relative to user location and in the user direction of travelling. We design an efficient algorithm based on Filter phase, Heap phase and Refine Skyline phases. At the end, we propose a dynamic skyline caching (DSC) mechanism which helps to reduce the computation cost for future skyline queries. The experimental evaluation reflects the performance of GD-RST algorithm over the traditional branch and bound algorithm for skyline queries in real road networks.
Time- and space-dependent electric response of Ovonic devices
Jacoboni, C.; Piccinini, E.; Brunetti, R.; Rudan, M.
2017-06-01
A time- and space-dependent 1D model including the self-consistent solution of the Poisson equation is presented to study the electric response of nanometer Ovonic samples. The model accounts for the main features of the relevant microscopic processes occurring inside the material, and is easily incorporated in commercial device-simulation tools. Numerical results are presented and discussed for Ovonic samples of different lengths and material parameters, and successfully compared to recent optimized experimental results for AgInTeSb. The analysis indicates a very short intrinsic response time of Ovonic devices, of the order of tens of ps and a minimum device length of the order of 5-10 nm, in order to guarantee the device functionality. Tests on the sensitivity of the model on some physical parameters have also been carried out.
Study of Time-Dependent Properties of Thermoplastics
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Bolchoun A.
2010-06-01
Full Text Available Simple tests carried out with a common tension/compression testing machine are used to obtain timedependent properties of non-reinforced thermoplastics. These tests include ramp loadings as well as relaxation and creep tests. Two materials (PBT Celanex 2002-2 and POM Hostaform C9021, Ticona GmbH, Kelsterbach were taken for the experiments. The experiments show that an adequate description of the long-term material properties can be obtained from the short-time tests, namely from tests with constant traverse speed $L^.$. Below a model for the time-dependent mechanical behavior is presented and fitted to the obtained measured data. For the evaluation of the fitting quality long-term tests are used. Especially creep and relaxation tests with ”jumps”, i.e. rapid change of loading, are important for this purpose.
Exponential time-dependent perturbation theory in rotationally inelastic scattering
Cross, R. J.
1983-08-01
An exponential form of time-dependent perturbation theory (the Magnus approximation) is developed for rotationally inelastic scattering. A phase-shift matrix is calculated as an integral in time over the anisotropic part of the potential. The trajectory used for this integral is specified by the diagonal part of the potential matrix and the arithmetic average of the initial and final velocities and the average orbital angular momentum. The exponential of the phase-shift matrix gives the scattering matrix and the various cross sections. A special representation is used where the orbital angular momentum is either treated classically or may be frozen out to yield the orbital sudden approximation. Calculations on Ar+N2 and Ar+TIF show that the theory generally gives very good agreement with accurate calculations, even where the orbital sudden approximation (coupled-states) results are seriously in error.
Multiaxial Temperature- and Time-Dependent Failure Model
Richardson, David; McLennan, Michael; Anderson, Gregory; Macon, David; Batista-Rodriquez, Alicia
2003-01-01
A temperature- and time-dependent mathematical model predicts the conditions for failure of a material subjected to multiaxial stress. The model was initially applied to a filled epoxy below its glass-transition temperature, and is expected to be applicable to other materials, at least below their glass-transition temperatures. The model is justified simply by the fact that it closely approximates the experimentally observed failure behavior of this material: The multiaxiality of the model has been confirmed (see figure) and the model has been shown to be applicable at temperatures from -20 to 115 F (-29 to 46 C) and to predict tensile failures of constant-load and constant-load-rate specimens with failure times ranging from minutes to months..
Dirac equation on coordinate dependent noncommutative space-time
Kupriyanov, V G
2014-01-01
We consider the consistent deformation of the relativistic quantum mechanics introducing the noncommutativity of the space-time and preserving the Lorentz symmetry. The relativistic wave equation describing the spinning particle on coordinate dependent noncommutative space-time (noncommutative Dirac equation) is proposed. The fundamental properties of this equation, like the Lorentz covariance and the continuity equation for the probability density are verified. To this end using the properties of the star product we derive the corresponding probability current density and prove its conservation. The energy-momentum tensor for the free noncommutative spinor field is calculated. We solve the free noncommutative Dirac equation and show that the standard energy-momentum dispersion relation remains valid in the noncommutative case.
Time-dependent resonant magneto-optical rotation
Dziczek, Dariusz
2015-01-01
Results of a fairly straightforward experiment on resonant magneto-optical rotation by rubidium-87 atoms revealed strong time-dependence of the polarization plane of light emerging from atomic vapors following a sudden irradiation with a laser beam. The rotation of the plane appears as a not direct consequence of the influence of the magnetic field on atoms. Reported measurements conducted using a vapor cell without any buffer gas or an anti-relaxation wall coating show that transmitted light has initially the same (linear) polarization as the incident one. Rotation of the polarization plane caused by an axial magnetic field develops in time scales similar to the pace of establishing the optical pumping/relaxation equilibrium in the atomic ensemble. The traditional passive Faraday rotation picture providing working description for the resonant magneto-optical effects in steady-state conditions does not explain the observed sequence of evolution of the polarization. The picture has to be augmented with analysi...
Hoffman, Adam J.; Lee, John C.
2016-02-01
A new time-dependent Method of Characteristics (MOC) formulation for nuclear reactor kinetics was developed utilizing angular flux time-derivative propagation. This method avoids the requirement of storing the angular flux at previous points in time to represent a discretized time derivative; instead, an equation for the angular flux time derivative along 1D spatial characteristics is derived and solved concurrently with the 1D transport characteristic equation. This approach allows the angular flux time derivative to be recast principally in terms of the neutron source time derivatives, which are approximated to high-order accuracy using the backward differentiation formula (BDF). This approach, called Source Derivative Propagation (SDP), drastically reduces the memory requirements of time-dependent MOC relative to methods that require storing the angular flux. An SDP method was developed for 2D and 3D applications and implemented in the computer code DeCART in 2D. DeCART was used to model two reactor transient benchmarks: a modified TWIGL problem and a C5G7 transient. The SDP method accurately and efficiently replicated the solution of the conventional time-dependent MOC method using two orders of magnitude less memory.
Time-dependent changes in altruistic punishment following stress.
Vinkers, Christiaan H; Zorn, Jelle V; Cornelisse, Sandra; Koot, Susanne; Houtepen, Lotte C; Olivier, Berend; Verster, Joris C; Kahn, René S; Boks, Marco P M; Kalenscher, Tobias; Joëls, Marian
2013-09-01
Decisions are rarely made in social isolation. One phenomenon often observed in social interactions is altruistic punishment, i.e. the punishment of unfair behavior by others at a personal cost. The tendency for altruistic punishment is altered by affective states including those induced by stress exposure. Stress is thought to exert bi-directional effects on behavior: immediately after stress, reflex-like and habitual behavior is promoted while later on more far-sighted, flexible and goal-directed behavior is enhanced. We hypothesized that such time-dependent effects of stress would also be present in the context of altruistic punishment behavior. Healthy male participants (N=80) were exposed to either a grouped stress test or a control condition. Participants were tested in prosocial decision making tasks either directly after stress or 75 min later. Altruistic punishment was assessed using the Ultimatum Game. General altruism was assessed with a one-shot version of the Dictator Game in which an anonymous donation could be offered to a charitable organization. We found that stress caused a bi-directional effect on altruistic punishment, with decreased rejection rates in the late aftermath of stress in response to ambiguous 30% offers. In the Dictator Game, stressed participants were less generous than controls, but no time-dependent effect was observed, indicating that the general reward sensitivity remained unchanged at various time-points after stress. Overall, during the late aftermath after acute stress exposure (i.e. 75 min later), participants acted more consistent with their own material self-interest, and had a lower propensity for altruistic punishment, possibly through upregulation of cognitive self-control mechanisms. Thus, our findings underscore the importance of time as a factor in simple, real-life economic decisions in a stressful social context.
Tao, Yuankai K.; El-Haddad, Mohamed T.; Srivastava, Sunil K.; Feiler, Daniel; Noonan, Amanda I.; Rollins, Andrew M.; Ehlers, Justis P.
2015-03-01
Ophthalmic surgical maneuvers are currently limited by the ability of surgeons to visualize and manipulate semitransparent tissue layers as thin as tens of microns. We describe several iterative advances in iOCT technology, including a novel iOCT system, real-time heads-up display (HUD) feedback, visualization of intraoperative maneuvers, and OCT-compatible surgical instrumentation. Simulated surgical maneuvers were performed on freshly enucleated porcine eyes. Subretinal space cannulation with injection was performed and imaged using spatial compounding. The optical properties of semitransparent materials were quantified to identify OCT-compatible substrates, and surgical instrument prototypes were machined, including corneal, surgical picks, and retinal forceps.
Solar Magnetic Flux Tube Simulations with Time-Dependent Ionization
Fawzy, Diaa E; Rammacher, Wolfgang
2012-01-01
In the present work we expand the study of time-dependent ionization previously identified to be of pivotal importance for acoustic waves in solar magnetic flux tube simulations. We focus on longitudinal tube waves (LTW) known to be an important heating agent of solar magnetic regions. Our models also consider new results of wave energy generation as well as an updated determination of the mixing length of convection now identified as 1.8 scale heights in the upper solar convective layers. We present 1-D wave simulations for the solar chromosphere by studying tubes of different spreading as function of height aimed at representing tubes in environments of different magnetic filling factors. Multi-level radiative transfer has been applied to correctly represent the total chromospheric emission function. The effects of time-dependent ionization are significant in all models studied. They are most pronounced behind strong shocks and in low density regions, i.e., the middle and high chromosphere. Concerning our m...
A collisional extension of time-dependent Hartree-Fock
Lacombe, L.; Reinhard, P.-G.; Dinh, P. M.; Suraud, E.
2016-12-01
We propose a collisional extension of time-dependent mean-field theories on the basis of a recently proposed stochastic extension of mean-field dynamics (stochastic time-dependent Hartree-Fock, STDHF). The latter theory is unfortunately too involved to envision practical applications in realistic systems in the near future and is thus bound to model systems. It is also hard to explore moderate to low energies with STDHF, because of vanishing transition probabilities that are impossible to sample properly. For such moderately excited situations covering small fluctuations, we compactify sampling by employing the same average mean field for all STDHF trajectories. The new approach, coined average STDHF (ASTDHF), ignores the fluctuations of the mean field but still accounts correctly for the collisional correlations responsible for dissipative features on top of mean-field dynamics. We detail the main features of the new approach in relation to existing equations, in particular quantum kinetic theories. The new theory is directly connected to STDHF, both formally and practically. We thus discuss in detail how the two approaches are related to each other. We apply the new scheme to illustrative examples taking as benchmark STDHF dynamics in 1D. ASTDHF provides results that are in remarkable agreement with the more elaborate STDHF. It makes it a promising approach to deal with dissipative dynamics in finite quantum systems, because of its moderate cost allowing applications in realistic systems and the possibility of exploring any excitation energy range where collisional correlations are expected to play a role.
Frequency-Dependent Dispersion Measures and Implications for Pulsar Timing
Cordes, J M; Stinebring, D R
2016-01-01
We analyze the frequency dependence of the dispersion measure (DM), the column density of free electrons to a pulsar, caused by multipath scattering from small scale electron-density fluctuations. The DM is slightly different along each propagation path and the transverse spread of paths varies greatly with frequency, yielding time-of-arrival (TOA) perturbations that scale differently than the inverse square of the frequency, the expected dependence for a cold, unmagnetized plasma. We quantify DM and TOA perturbations analytically for thin phase screens and extended media and verify the results with simulations of thin screens. The rms difference between DMs across an octave band near 1.5~GHz $\\sim 4\\times10^{-5}\\,{\\rm pc\\ cm^{-3}}$ for pulsars at $\\sim 1$~kpc distance. TOA errors from chromatic DMs are of order a few to hundreds of nanoseconds for pulsars with DM $\\lesssim 30$~pc~cm$^{-3}$ observed across an octave band but increase rapidly to microseconds or larger for larger DMs and wider frequency ranges....
Spike-timing dependent plasticity in the striatum
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Elodie Fino
2010-06-01
Full Text Available The striatum is the major input nucleus of basal ganglia, an ensemble of interconnected sub-cortical nuclei associated with fundamental processes of action-selection and procedural learning and memory. The striatum receives afferents from the cerebral cortex and the thalamus. In turn, it relays the integrated information towards the basal ganglia output nuclei through which it operates a selected activation of behavioral effectors. The striatal output neurons, the GABAergic medium-sized spiny neurons (MSNs, are in charge of the detection and integration of behaviorally relevant information. This property confers to the striatum the ability to extract relevant information from the background noise and select cognitive-motor sequences adapted to environmental stimuli. As long-term synaptic efficacy changes are believed to underlie learning and memory, the corticostriatal long-term plasticity provides a fundamental mechanism for the function of the basal ganglia in procedural learning. Here, we reviewed the different forms of spike-timing dependent plasticity (STDP occurring at corticostriatal synapses. Most of the studies have focused on MSNs and their ability to develop long-term plasticity. Nevertheless, the striatal interneurons (the fast-spiking GABAergic, the NO synthase and cholinergic interneurons also receive monosynaptic afferents from the cortex and tightly regulated corticostriatal information processing. Therefore, it is important to take into account the variety of striatal neurons to fully understand the ability of striatum to develop long-term plasticity. Corticostriatal STDP with various spike-timing dependence have been observed depending on the neuronal sub-populations and experimental conditions. This complexity highlights the extraordinary potentiality in term of plasticity of the corticostriatal pathway.
Time-dependent compaction band formation in sandstone
Heap, Michael J.; Brantut, Nicolas; Baud, Patrick; Meredith, Philip G.
2015-07-01
Compaction bands in sandstone are laterally extensive planar deformation features that are characterized by lower porosity and permeability than the surrounding host rock. As a result, this form of localization has important implications for both strain partitioning and fluid flow in the Earth's upper crust. To better understand the time dependency of compaction band growth, we performed triaxial deformation experiments on water-saturated Bleurswiller sandstone (initial porosity = 0.24) under constant stress (creep) conditions in the compactant regime. Our experiments show that inelastic strain accumulates at a constant stress in the compactant regime, manifest as compaction bands. While creep in the dilatant regime is characterized by an increase in porosity and, ultimately, an acceleration in axial strain rate to shear failure, compaction creep is characterized by a reduction in porosity and a gradual deceleration in axial strain rate. The global decrease in the rates of axial strain, acoustic emission energy, and porosity change during creep compaction is punctuated at intervals by higher rate excursions, interpreted as the formation of compaction bands. The growth rate of compaction bands formed during creep is lower as the applied differential stress, and hence, background creep strain rate, is decreased. However, the inelastic strain associated with the growth of a compaction band remains constant over strain rates spanning several orders of magnitude (from 10-8 to 10-5 s-1). We find that despite the large differences in strain rate and growth rate (from both creep and constant strain rate experiments), the characteristics (geometry and thickness) of the compaction bands remain essentially the same. Several lines of evidence, notably the similarity between the differential stress dependence of creep strain rate in the dilatant and compactant regimes, suggest that as for dilatant creep, subcritical stress corrosion cracking is the mechanism responsible for
Magnetic circular dichroism in real-time time-dependent density functional theory
Lee, K -M; Bertsch, G F
2010-01-01
We apply the adiabatic time-dependent density functional theory to magnetic ci the real-space, real-time computational method. The standard formulas for the MCD response and its A and B terms are derived from the observables in the time-dependent wave function. We find the real time method is well suited for calculating the overall spectrum, particularly at higher excitation energies where individual excited states are numerous and overlapping. The MCD sum rules are derived and interpreted in the real-time formalism; we find that they are very useful for normalization purposes and assessing the accuracy of the theory. The method is applied to MCD spectrum of C-60 using the adiabatic energy functional from the local density approximation. The theory correctly predicts the signs of the A and B terms for the lowest allowed excitations. However, the magnitudes of the terms only show qualitative agreement with experiment.
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Mac-Thiong Jean-Marc
2009-02-01
Full Text Available Abstract Background The correction of trunk deformity is crucial in scoliosis surgery, especially for the patient's self-image. However, direct visualization of external scoliotic trunk deformity during surgical correction is difficult due to the covering draping sheets. Methods An optoelectronic camera system with 10 passive markers is used to track the trunk geometry of 5 scoliotic patients during corrective surgery. The position of 10 anatomical landmarks and 5 trunk indices computed from the position of the passive markers are compared during and after instrumentation of the spine. Results Internal validation of the accuracy of tracking was evaluated at 0.41 +/- 0.05 mm RMS. Intra operative tracking during surgical maneuvers shows improvement of the shoulder balance during and after correction of the spine. Improvement of the overall patient balance is observed. At last, a minor increase of the spinal length can be noticed. Conclusion Tracking of the external geometry of the trunk during surgical correction is useful to monitor changes occurring under the sterile draping sheets. Moreover, this technique can used be used to reach the optimal configuration on the operating frame before proceeding to surgery. The current tracking technique was able to detect significant changes in trunk geometry caused by posterior instrumentation of the spine despite significant correction of the spinal curvature. It could therefore become relevant for computer-assisted guidance of surgical maneuvers when performing posterior instrumentation of the scoliotic spine, provide important insights during positioning of patients.
Time-dependent cortical activation in voluntary muscle contraction.
Yang, Qi; Wang, Xiaofeng; Fang, Yin; Siemionow, Vlodek; Yao, Wanxiang; Yue, Guang H
2011-01-01
This study was to characterize dynamic source strength changes estimated from high-density scalp electroencephalogram (EEG) at different phases of a submaximal voluntary muscle contraction. Eight healthy volunteers performed isometric handgrip contractions of the right arm at 20% maximal intensity. Signals of the handgrip force, electromyography (EMG) from the finger flexor and extensor muscles and 64-channel EEG were acquired simultaneously. Sources of the EEG were analyzed at 19 time points across preparation, execution and sustaining phases of the handgrip. A 3-layer boundary element model (BEM) based on the MNI (Montréal Neurological Institute) brain MRI was used to overlay the sources. A distributed current density model, LORETA L1 norm method was applied to the data that had been processed by independent component analysis (ICA). Statistical analysis based on a mixed-effects polynomial regression model showed a significant and consistent time-dependent non-linear source strength change pattern in different phases of the handgrip. The source strength increased at the preparation phase, peaked at the force onset time and decreased in the sustaining phase. There was no significant difference in the changing pattern of the source strength among Brodmann's areas 1, 2, 3, 4, and 6. These results show, for the first time, a high time resolution increasing-and-decreasing pattern of activation among the sensorimotor regions with the highest activity occurs at the muscle activity onset. The similarity in the source strength time courses among the cortical centers examined suggests a synchronized parallel function in controlling the motor activity.
Two-Agent Single-Machine Scheduling of Jobs with Time-Dependent Processing Times and Ready Times
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Jan-Yee Kung
2013-01-01
Full Text Available Scheduling involving jobs with time-dependent processing times has recently attracted much research attention. However, multiagent scheduling with simultaneous considerations of jobs with time-dependent processing times and ready times is relatively unexplored. Inspired by this observation, we study a two-agent single-machine scheduling problem in which the jobs have both time-dependent processing times and ready times. We consider the model in which the actual processing time of a job of the first agent is a decreasing function of its scheduled position while the actual processing time of a job of the second agent is an increasing function of its scheduled position. In addition, each job has a different ready time. The objective is to minimize the total completion time of the jobs of the first agent with the restriction that no tardy job is allowed for the second agent. We propose a branch-and-bound and several genetic algorithms to obtain optimal and near-optimal solutions for the problem, respectively. We also conduct extensive computational results to test the proposed algorithms and examine the impacts of different problem parameters on their performance.
Delay and Its Time-Derivative Dependent Bounded Real Lemma for Linear Time-Delay Systems
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JIANGXiefu; XUWenli
2004-01-01
Based on an appropriate Lyapunov-Krasovskii functional, this paper deals with the problem of the bounded real lemma for linear continuous-time systems with state delay. The system under consideration involves state time-varying time-delay. A sufficient condition for the system to possess a H∞-norm that is less than a prescribed level, is presented in a Linear matrix inequality(LMI) form which is dependent on both the size of timedelay and the size of its time-derivative. Due to that fewercross terms should be bounded, our result is less conservative. Finally, an example is presented to demonstrate the effectiveness of our result.
Weston, Matthew; Weston, Kathryn L; Prentis, James M; Snowden, Chris P
2016-01-01
The advancement of perioperative medicine is leading to greater diversity in development of pre-surgical interventions, implemented to reduce patient surgical risk and enhance post-surgical recovery. Of these interventions, the prescription of pre-operative exercise training is gathering momentum as a realistic means for enhancing patient surgical outcome. Indeed, the general benefits of exercise training have the potential to pre-operatively optimise several pre-surgical risks factors, including cardiorespiratory function, frailty and cognitive function. Any exercise programme incorporated into the pre-operative pathway of care needs to be effective and time efficient in that any fitness gains are achievable in the limited period between the decision for surgery and operation (e.g. 4 weeks). Fortunately, there is a large volume of research describing effective and time-efficient exercise training programmes within the discipline of sports science. Accordingly, the objective of our commentary is to synthesise contemporary exercise training research, both from non-clinical and clinical populations, with the overarching aim of informing the development of effective and time-efficient pre-surgical exercise training programmes. The development of such exercise training programmes requires the careful consideration of several key principles, namely frequency, intensity, time, type and progression of exercise. Therefore, in light of more recent evidence demonstrating the effectiveness and time efficiency of high-intensity interval training-which involves brief bouts of intense exercise interspersed with longer recovery periods-the principles of exercise training programme design will be discussed mainly in the context of such high-intensity interval training programmes. Other issues pertinent to the development, implementation and evaluation of pre-operative exercise training programmes, such as individual exercise prescription, training session monitoring and potential
Time Dependent Couplings as Observables in de Sitter Space
Kitamoto, Hiroyuki
2014-01-01
We summarize and expand our investigations concerning the soft graviton effects on microscopic matter dynamics in de Sitter space. The physical couplings receive IR logarithmic corrections which are sensitive to the IR cut-off at the one-loop level. The scale invariant spectrum in the gravitational propagator at the super-horizon scale is the source of the de Sitter symmetry breaking. The quartic scalar, Yukawa and gauge couplings become time dependent and diminish with time. In contrast, the Newton's constant increases with time. We clarify the physical mechanism behind these effects in terms of the conformal mode dynamics in analogy with 2d quantum gravity. We show that they are the inevitable consequence of the general covariance and lead to gauge invariant predictions. We construct a simple model in which the cosmological constant is self-tuned to vanish due to UV-IR mixing effect. We also discuss phenomenological implications such as decaying Dark Energy and SUSY breaking at the Inflation era. The quantu...
Time-dependent models of dense PDRs with complex molecules
Morata, O
2008-01-01
We present a study of the chemistry of a dense photon-dominated region (PDR) using a time-dependent chemical model. Our major interest is to study the spatial distribution of complex molecules such as hydrocarbons and cyanopolyynes in the cool dense material bordering regions where star formation has taken place. Our standard model uses a homogeneous cloud of density 2x10e4 cm-3 and temperature T=40 K, which is irradiated by a far-ultraviolet radiation field of intermediate intensity, given by X=100. We find that over a range of times unsaturated hydrocarbons (e.g., C2H, C4H, C3H2) have relatively high fractional abundances in the more external layers of the PDR, whereas their abundances in the innermost layers are several orders of magnitudes lower. On the other hand, molecules that are typical of late-time chemistry are usually more abundant in the inner parts of the PDR. We also present results for models with different density, temperature, intensity of the radiation field and initial fractional abundance...
On exceedance times for some processes with dependent increments
Asmussen, Søren
2012-01-01
Let ${Z_n}_{n\\ge 0}$ be a random walk with a negative drift and i.i.d. increments with heavy-tailed distribution and let $M=\\sup_{n\\ge 0}Z_n$ be its supremum. Asmussen & Kl{\\"u}ppelberg (1996) considered the behavior of the random walk given that $M>x$, for $x$ large, and obtained a limit theorem, as $x\\to\\infty$, for the distribution of the quadruple that includes the time $\\rtreg=\\rtreg(x)$ to exceed level $x$, position $Z_{\\rtreg}$ at this time, position $Z_{\\rtreg-1}$ at the prior time, and the trajectory up to it (similar results were obtained for the Cram\\'er-Lundberg insurance risk process). We obtain here several extensions of this result to various regenerative-type models and, in particular, to the case of a random walk with dependent increments. Particular attention is given to describing the limiting conditional behavior of $\\tau$. The class of models include Markov-modulated models as particular cases. We also study fluid models, the Bj{\\"o}rk-Grandell risk process, give examples where the or...
Improving the Prediction of Total Surgical Procedure Time Using Linear Regression Modeling.
Edelman, Eric R; van Kuijk, Sander M J; Hamaekers, Ankie E W; de Korte, Marcel J M; van Merode, Godefridus G; Buhre, Wolfgang F F A
2017-01-01
For efficient utilization of operating rooms (ORs), accurate schedules of assigned block time and sequences of patient cases need to be made. The quality of these planning tools is dependent on the accurate prediction of total procedure time (TPT) per case. In this paper, we attempt to improve the accuracy of TPT predictions by using linear regression models based on estimated surgeon-controlled time (eSCT) and other variables relevant to TPT. We extracted data from a Dutch benchmarking database of all surgeries performed in six academic hospitals in The Netherlands from 2012 till 2016. The final dataset consisted of 79,983 records, describing 199,772 h of total OR time. Potential predictors of TPT that were included in the subsequent analysis were eSCT, patient age, type of operation, American Society of Anesthesiologists (ASA) physical status classification, and type of anesthesia used. First, we computed the predicted TPT based on a previously described fixed ratio model for each record, multiplying eSCT by 1.33. This number is based on the research performed by van Veen-Berkx et al., which showed that 33% of SCT is generally a good approximation of anesthesia-controlled time (ACT). We then systematically tested all possible linear regression models to predict TPT using eSCT in combination with the other available independent variables. In addition, all regression models were again tested without eSCT as a predictor to predict ACT separately (which leads to TPT by adding SCT). TPT was most accurately predicted using a linear regression model based on the independent variables eSCT, type of operation, ASA classification, and type of anesthesia. This model performed significantly better than the fixed ratio model and the method of predicting ACT separately. Making use of these more accurate predictions in planning and sequencing algorithms may enable an increase in utilization of ORs, leading to significant financial and productivity related benefits.
Improving the Prediction of Total Surgical Procedure Time Using Linear Regression Modeling
Directory of Open Access Journals (Sweden)
Eric R. Edelman
2017-06-01
Full Text Available For efficient utilization of operating rooms (ORs, accurate schedules of assigned block time and sequences of patient cases need to be made. The quality of these planning tools is dependent on the accurate prediction of total procedure time (TPT per case. In this paper, we attempt to improve the accuracy of TPT predictions by using linear regression models based on estimated surgeon-controlled time (eSCT and other variables relevant to TPT. We extracted data from a Dutch benchmarking database of all surgeries performed in six academic hospitals in The Netherlands from 2012 till 2016. The final dataset consisted of 79,983 records, describing 199,772 h of total OR time. Potential predictors of TPT that were included in the subsequent analysis were eSCT, patient age, type of operation, American Society of Anesthesiologists (ASA physical status classification, and type of anesthesia used. First, we computed the predicted TPT based on a previously described fixed ratio model for each record, multiplying eSCT by 1.33. This number is based on the research performed by van Veen-Berkx et al., which showed that 33% of SCT is generally a good approximation of anesthesia-controlled time (ACT. We then systematically tested all possible linear regression models to predict TPT using eSCT in combination with the other available independent variables. In addition, all regression models were again tested without eSCT as a predictor to predict ACT separately (which leads to TPT by adding SCT. TPT was most accurately predicted using a linear regression model based on the independent variables eSCT, type of operation, ASA classification, and type of anesthesia. This model performed significantly better than the fixed ratio model and the method of predicting ACT separately. Making use of these more accurate predictions in planning and sequencing algorithms may enable an increase in utilization of ORs, leading to significant financial and productivity related
Computing Finite-Time Lyapunov Exponents with Optimally Time Dependent Reduction
Babaee, Hessam; Farazmand, Mohammad; Sapsis, Themis; Haller, George
2016-11-01
We present a method to compute Finite-Time Lyapunov Exponents (FTLE) of a dynamical system using Optimally Time-Dependent (OTD) reduction recently introduced by H. Babaee and T. P. Sapsis. The OTD modes are a set of finite-dimensional, time-dependent, orthonormal basis {ui (x , t) } |i=1N that capture the directions associated with transient instabilities. The evolution equation of the OTD modes is derived from a minimization principle that optimally approximates the most unstable directions over finite times. To compute the FTLE, we evolve a single OTD mode along with the nonlinear dynamics. We approximate the FTLE from the reduced system obtained from projecting the instantaneous linearized dynamics onto the OTD mode. This results in a significant reduction in the computational cost compared to conventional methods for computing FTLE. We demonstrate the efficiency of our method for double Gyre and ABC flows. ARO project 66710-EG-YIP.
A time-dependent method of characteristics formulation with time derivative propagation
Hoffman, Adam J.
We developed a new time-dependent neutron transport method for nuclear reactor kinetics using method of characteristics (MOC) with angular flux time derivative propagation. In contrast to conventional time integration methods which use local finite difference approximations to treat the time derivative, the new method solves for the spatially-dependent angular flux time derivative by propagation along characteristics in space. This results in the angular flux time derivative being recast in terms of the neutron source time derivatives, and thus the new method is called Source Derivative Propagation (SDP). We developed three SDP methods using different approximations, and they require much less memory than the conventional methods. For SDP, we approximate the source derivatives using backward differences. This is analogous to the backward differentiation formula (BDF), and our results confirmed that the high-order SDP approximations reproduced the high-order angular flux derivative approximation of equivalent order BDF. We assessed SDP by comparison to conventional time-dependent MOC methods. This included both a reference method (RBDC) which stored the angular flux and a popular approximate method (IBDC). We performed error analysis for SDP, RBDC, and IBDC. This informed the refinement of the SDP methods, and clarified when SDP will be accurate. We tested SDP using the computer code DeCART, which was used to model three transients based on the TWIGL and C5G7 benchmarks. A fine time step reference solution was generated using RBDC. The SDP methods converged to the reference when the time step was refined and the BDF order increased. In addition, we observed that SDP accurately replicated the RBDC solution when the same time step and BDF order was used. This indicates that the propagated angular flux time derivative of SDP reproduced the RBDC angular flux derivative. SDP was much more accurate than the IBDC. We assessed the efficiency of SDP by comparing the run-time
Fuzzy economic production quantity model with time dependent demand rate
Directory of Open Access Journals (Sweden)
Susanta Kumar Indrajitsingha
2016-09-01
Full Text Available Background: In this paper, an economic production quantity model is considered under a fuzzy environment. Both the demand cost and holding cost are considered using fuzzy pentagonal numbers. The Signed Distance Method is used to defuzzify the total cost function. Methods: The results obtained by these methods are compared with the help of a numerical example. Sensitivity analysis is also carried out to explore the effect of changes in the values of some of the system parameters. Results and conclusions: The fuzzy EPQ model with time dependent demand rate was presented together with the possible implementation. The behavior of changes in parameters was analyzed. The possible extension of the implementation of this method was presented.
Large blue isocurvature spectral index signals time-dependent mass
Chung, Daniel J. H.
2016-08-01
We show that if a spectator linear isocurvature dark matter field degree of freedom has a constant mass through its entire evolution history, the maximum measurable isocurvature spectral index that is consistent with the current tensor-to-scalar ratio bound of about r ≲0.1 is about nI≲2.4 , even if experiments can be sensitive to a 10-6 contamination of the predominantly adiabatic power spectrum with an isocurvature power spectrum at the shortest observable length scales. Hence, any foreseeable future measurement of a blue isocurvature spectral index larger than ˜2.4 may provide nontrivial evidence for dynamical degrees of freedom with time-dependent masses during inflation. The bound is not sensitive to the details of the reheating scenario and can be made mildly smaller if r is better constrained in the future.
Time-dependent particle acceleration in a Fermi reservoir
Litvinenko, Y. E.
2012-08-01
Context. A steady model was presented by Burn, in which energy conservation is used to constrain the parameters of stochastic Fermi acceleration. A steady model, however, is unlikely to be adequate for particle acceleration in impulsive solar flares. Aims: This paper describes a time-dependent model for particle acceleration in a Fermi reservoir Methods: The calculation is based on the original formulation of stochastic acceleration by Fermi, with additional physically motivated assumptions about the turbulent and particle energy densities within the reservoir, that are similar to those of the steady analysis. The problem is reduced to an integro-differential equation that possesses an analytical solution. Results: The model predicts the formation of a power-law differential energy spectrum N(E) ~ E-2, that is observable outside the reservoir. The predicted spectral index is independent of the parameters of the model. The results may help in understanding particle acceleration in solar flares and other astrophysical applications.
Time-dependent calculations in Potassium mid-infrared wavelengths
Maragakis, P; Lambropoulos, P
1999-01-01
We study the dynamics of the Potassium atom in the mid-infrared, high intensity, short laser pulse regime. We ascertain our numerical convergence by comparing the results of two different propagation methods of the time-dependent Schroedinger equation. We present ionization curves in the 12-, 13-, and 14-photon ionization range for Potassium. The ionization curve of a scaled system, namely Hydrogen starting from the 2s, is compared to the 12-photon results. In the 13-photon regime, a dynamic resonance is observed and analyzed in more detail. The results for all wavelengths and intensities, including the case of Hydrogen, display a clear plateau formation in the peak-heights of the low energy part of the Above Threshold Ionization (ATI) spectrum, which scales with the ponderomotive energy Up, and extends to (2.8 +- 0.5) Up.
Time-dependent interactions between iboga agents and cocaine.
Maisonneuve, I M; Visker, K E; Mann, G L; Bandarage, U K; Kuehne, M E; Glick, S D
1997-10-08
The purpose of this study was to clarify the effects of iboga agents on cocaine-induced hyperactivity. Both inhibition and enhancement of cocaine-induced activity by ibogaine have been reported. In the present study, rats were treated with either ibogaine (40 mg/kg, i.p.), noribogaine (40 mg/kg, i.p.), 18-methoxycoronaridine (40 mg/kg, i.p.), or saline, 1 or 19 h prior to the administration of cocaine (20 mg/kg, i.p.) or saline. Motor activity was monitored thereafter for 3 h. All three iboga agents had acute inhibitory effects and delayed potentiating effects on cocaine-induced hyperactivity. These time-dependent effects, which could not be attributed to the motor activity induced by the iboga agents alone, account for divergent results reported in the literature.
On a time-dependent extra spatial dimension
Kuhfittig, P K F
2006-01-01
In the usual brane-world scenario matter fields are confined to the four-dimensional spacetime, called a 3-brane, embedded in a higher-dimensional space, usually referred to as the bulk spacetime. In this paper we assume that the 3-brane a de Sitter space; there is only one extra spatial dimension, assumed to be time dependent. By using the form of the brane-world energy-momentum tensor suggested by Shiromizu et al. in the five-dimensional Einstein equations, it is shown that whenever the bulk cosmological constant \\Lambda is negative, the extra spatial dimension rapidly shrinks during the inflation of the brane. When \\Lambda>0, on the other hand, the extra spatial dimension either completely follows the cosmological expansion of the brane or completely ignores it. This behavior resembles the all-or-nothing behavior of ordinary systems in an expanding universe, as recently demonstrated by R.H. Price.
Spin-orbit torque induced spike-timing dependent plasticity
Energy Technology Data Exchange (ETDEWEB)
Sengupta, Abhronil, E-mail: asengup@purdue.edu; Al Azim, Zubair; Fong, Xuanyao; Roy, Kaushik [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)
2015-03-02
Nanoelectronic devices that mimic the functionality of synapses are a crucial requirement for performing cortical simulations of the brain. In this work, we propose a ferromagnet-heavy metal heterostructure that employs spin-orbit torque to implement spike-timing dependent plasticity. The proposed device offers the advantage of decoupled spike transmission and programming current paths, thereby leading to reliable operation during online learning. Possible arrangement of such devices in a crosspoint architecture can pave the way for ultra-dense neural networks. Simulation studies indicate that the device has the potential of achieving pico-Joule level energy consumption (maximum 2 pJ per synaptic event) which is comparable to the energy consumption for synaptic events in biological synapses.
A gauge invariant theory for time dependent heat current
Chen, Jian; ShangGuan, Minhui; Wang, Jian
2015-05-01
In this work, we develop a general gauge-invariant theory for AC heat current through multi-probe systems. Using the non-equilibrium Green’s function, a general expression for time-dependent electrothermal admittance is obtained where we include the internal potential due to the Coulomb interaction explicitly. We show that the gauge-invariant condition is satisfied for heat current if the self-consistent Coulomb interaction is considered. It is known that the Onsager relation holds for dynamic charge conductance. We show in this work that the Onsager relation for electrothermal admittance is violated, except for a special case of a quantum dot system with a single energy level. We apply our theory to a nano capacitor where the Coulomb interaction plays an essential role. We find that, to the first order in frequency, the heat current is related to the electrochemical capacitance as well as the phase accumulated in the scattering event.
Measuring time-dependent diffusion in polymer matrix composites
Energy Technology Data Exchange (ETDEWEB)
Pilli, Siva Prasad; Smith, Lloyd V.; Shutthanandan, V.
2014-11-01
Moisture plays a significant role in influencing the mechanical behavior and long-term durability of polymer matrix composites (PMC’s). The common methods used to determine the moisture diffusion coefficients of PMCs are based on the solution of Fickian diffusion in the one-dimensional domain. Fick’s Law assumes that equilibrium between the material surface and the external vapor is established instantaneously. A time dependent boundary condition has been shown to improve correlation with some bulk diffusion measurements, but has not been validated experimentally. The surface moisture content in a Toray 800S/3900-2B toughened quasi-isotropic laminate system, [0/±60]s, was analyzed experimentally using Nuclear Reaction Analysis (NRA). It was found that the surface moisture content showed a rapid increase to an intermediate concentration C0, followed by a slow linear increase to the saturation level.
Time-dependent Corotation Resonance in Barred Galaxies
Wu, Yu-Ting; Pfenniger, Daniel; Taam, Ronald E.
2016-10-01
The effective potential neighboring the corotation resonance region in barred galaxies is shown to be strongly time-dependent in any rotating frame, due to the competition of nearby perturbations of similar strengths with differing rotation speeds. Contrary to the generally adopted assumption that in the bar rotating frame the corotation region should possess four stationary equilibrium points (Lagrange points), with high quality N-body simulations, we localize the instantaneous equilibrium points (EPs) and find that they circulate or oscillate broadly in azimuth with respect to the pattern speeds of the inner or outer perturbations. This implies that at the particle level the Jacobi integral is not well conserved around the corotation radius. That is, angular momentum exchanges decouple from energy exchanges, enhancing the chaotic diffusion of stars through the corotation region.
The time-dependent Aharonov–Casher effect
Directory of Open Access Journals (Sweden)
Douglas Singleton
2016-02-01
Full Text Available In this paper we give a covariant expression for Aharonov–Casher phase. This expression is a combination of the canonical electric field, Aharonov–Casher phase plus a magnetic field phase shift. We use this covariant expression for the Aharonov–Casher phase to investigate the case of a neutral particle with a non-zero magnetic moment moving in the time dependent electric and magnetic fields of a plane electromagnetic wave background. We focus on the case where the magnetic moment of the particle is oriented so that both the electric and magnetic fields lead to non-zero phases, and we look at the interplay between these electric and magnetic phases.
The time-dependent Aharonov-Casher effect
Singleton, Douglas
2015-01-01
In this paper we give a covariant expression for Aharonov-Casher phase. This expression is a combination of the canonical electric field, Aharonov-Casher phase plus a magnetic field phase shift. We use this covariant expression for the Aharonov-Casher phase to investigate the case of a neutral particle with a non-zero magnetic moment moving in the {\\it time dependent} electric and magnetic fields of a plane electromagnetic wave background. We focus on the case where the magnetic moment of the particle is oriented so that both the electric and magnetic field lead to non-zero phases, and we look at the interplay between these electric and magnetic phases.
The time-dependent Aharonov–Casher effect
Energy Technology Data Exchange (ETDEWEB)
Singleton, Douglas, E-mail: dougs@csufresno.edu [Department of Physics, California State University Fresno, Fresno, CA 93740-8031 (United States); ICTP South American Institute for Fundamental Research, UNESP – Univ. Estadual Paulista, Rua Dr. Bento T. Ferraz 271, 01140-070, São Paulo, SP (Brazil); Ulbricht, Jaryd, E-mail: julbrich@ucsc.edu [Physics Department, University of California Santa Cruz, Santa Cruz, CA 95064 (United States); Department of Physics, California State University Fresno, Fresno, CA 93740-8031 (United States)
2016-02-10
In this paper we give a covariant expression for Aharonov–Casher phase. This expression is a combination of the canonical electric field, Aharonov–Casher phase plus a magnetic field phase shift. We use this covariant expression for the Aharonov–Casher phase to investigate the case of a neutral particle with a non-zero magnetic moment moving in the time dependent electric and magnetic fields of a plane electromagnetic wave background. We focus on the case where the magnetic moment of the particle is oriented so that both the electric and magnetic fields lead to non-zero phases, and we look at the interplay between these electric and magnetic phases.
The time-dependent Aharonov-Casher effect
Singleton, Douglas; Ulbricht, Jaryd
2016-02-01
In this paper we give a covariant expression for Aharonov-Casher phase. This expression is a combination of the canonical electric field, Aharonov-Casher phase plus a magnetic field phase shift. We use this covariant expression for the Aharonov-Casher phase to investigate the case of a neutral particle with a non-zero magnetic moment moving in the time dependent electric and magnetic fields of a plane electromagnetic wave background. We focus on the case where the magnetic moment of the particle is oriented so that both the electric and magnetic fields lead to non-zero phases, and we look at the interplay between these electric and magnetic phases.
Painleve V and time-dependent Jacobi polynomials
Energy Technology Data Exchange (ETDEWEB)
Basor, Estelle [American Institute of Mathematics, Palo Alto, CA 94306 (United States); Chen Yang [Department of Mathematics, Imperial College London, 180 Queen' s Gates, London SW7 2BZ (United Kingdom); Ehrhardt, Torsten [Department of Mathematics, University of California, Santa Cruz, CA 95064 (United States)], E-mail: ebasor@aimath.org, E-mail: ychen@imperial.ac.uk, E-mail: ehrhardt@math.ucsc.edu
2010-01-08
In this paper we study the simplest deformation on a sequence of orthogonal polynomials. This in turn induces a deformation on the moment matrix of the polynomials and associated Hankel determinant. We replace the original (or reference) weight w{sub 0}(x) (supported on R or subsets of R) by w{sub 0}(x) e{sup -tx}. It is a well-known fact that under such a deformation the recurrence coefficients denoted as {alpha}{sub n} and {beta}{sub n} evolve in t according to the Toda equations, giving rise to the time-dependent orthogonal polynomials and time-dependent determinants, using Sogo's terminology. If w{sub 0} is the normal density e{sup -x{sup 2}}, x element of R, or the gamma density x{sup {alpha}} e{sup -x}, x element of R{sub +}, {alpha} > -1, then the initial value problem of the Toda equations can be trivially solved. This is because under elementary scaling and translation the orthogonality relations reduce to the original ones. However, if w{sub 0} is the beta density (1 - x){sup {alpha}}(1 + x){sup {beta}}, x in [ - 1, 1], {alpha}, {beta} > -1, the resulting 'time-dependent' Jacobi polynomials will again satisfy a linear second-order ode, but no longer in the Sturm-Liouville form, which is to be expected. This deformation induces an irregular singular point at infinity in addition to three regular singular points of the hypergeometric equation satisfied by the Jacobi polynomials. We will show that the coefficients of this ode, as well as the Hankel determinant, are intimately related to a particular Painleve V. In particular we show that p{sub 1}(n,t), where p{sub 1}(n,t) is the coefficient of z{sup n-1} of the monic orthogonal polynomials associated with the 'time-dependent' Jacobi weight, satisfies, up to a translation in t, the Jimbo-Miwa {sigma}-form of the same P{sub V}; while a recurrence coefficient {alpha}{sub n}(t) is up to a translation in t and a linear fractional transformation P{sub V}({alpha}{sup 2}/2, - {beta}{sup 2
Time-dependent Corotation Resonance in Barred Galaxies
Wu, Yu-Ting; Taam, Ronald E
2016-01-01
The effective potential neighboring the corotation resonance region in barred galaxies is shown to be strongly time-dependent in any rotating frame because of the competition of nearby perturbations of similar strengths with differing rotation speeds. Contrary to the generally adopted assumption, that in the bar rotating frame the corotation region should possess four stationary equilibrium points (Lagrange points), with high quality N-body simulations we localize the instantaneous equilibrium points and find that they circulate or oscillate broadly in azimuth with respect to the pattern speeds of the inner or outer perturbations. This implies that at the particle level the Jacobi integral is not well conserved around the corotation radius. That is, angular momentum exchanges decouple from energy exchanges, enhancing the chaotic diffusion of stars through the corotation region.
Time-dependent reliability analysis and condition assessment of structures
Energy Technology Data Exchange (ETDEWEB)
Ellingwood, B.R. [Johns Hopkins Univ., Baltimore, MD (United States)
1997-01-01
Structures generally play a passive role in assurance of safety in nuclear plant operation, but are important if the plant is to withstand the effect of extreme environmental or abnormal events. Relative to mechanical and electrical components, structural systems and components would be difficult and costly to replace. While the performance of steel or reinforced concrete structures in service generally has been very good, their strengths may deteriorate during an extended service life as a result of changes brought on by an aggressive environment, excessive loading, or accidental loading. Quantitative tools for condition assessment of aging structures can be developed using time-dependent structural reliability analysis methods. Such methods provide a framework for addressing the uncertainties attendant to aging in the decision process.
SYMTRAN - A Time-dependent Symmetric Tandem Mirror Transport Code
Energy Technology Data Exchange (ETDEWEB)
Hua, D; Fowler, T
2004-06-15
A time-dependent version of the steady-state radial transport model in symmetric tandem mirrors in Ref. [1] has been coded up and first tests performed. Our code, named SYMTRAN, is an adaptation of the earlier SPHERE code for spheromaks, now modified for tandem mirror physics. Motivated by Post's new concept of kinetic stabilization of symmetric mirrors, it is an extension of the earlier TAMRAC rate-equation code omitting radial transport [2], which successfully accounted for experimental results in TMX. The SYMTRAN code differs from the earlier tandem mirror radial transport code TMT in that our code is focused on axisymmetric tandem mirrors and classical diffusion, whereas TMT emphasized non-ambipolar transport in TMX and MFTF-B due to yin-yang plugs and non-symmetric transitions between the plugs and axisymmetric center cell. Both codes exhibit interesting but different non-linear behavior.
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.
Schäfer, Karl-Christian; Balog, Júlia; Szaniszló, Tamás; Szalay, Dániel; Mezey, Géza; Dénes, Júlia; Bognár, László; Oertel, Matthias; Takáts, Zoltán
2011-10-15
Direct combination of cavitron ultrasonic surgical aspirator (CUSA) and sonic spray ionization mass spectrometry is presented. A commercially available ultrasonic surgical device was coupled to a Venturi easy ambient sonic-spray ionization (V-EASI) source by directly introducing liquified tissue debris into the Venturi air jet pump. The Venturi air jet pump was found to efficiently nebulize the suspended tissue material for gas phase ion production. The ionization mechanism involving solely pneumatic spraying was associated with that of sonic spray ionization. Positive and negative ionization spectra were obtained from brain and liver samples reflecting the primary application areas of the surgical device. Mass spectra were found to feature predominantly complex lipid-type constituents of tissues in both ion polarity modes. Multiply charged peptide anions were also detected. The influence of instrumental settings was characterized in detail. Venturi pump geometry and flow parameters were found to be critically important in ionization efficiency. Standard solutions of phospholipids and peptides were analyzed in order to test the dynamic range, sensitivity, and suppression effects. The spectra of the intact tissue specimens were found to be highly specific to the histological tissue type. The principal component analysis (PCA) and linear discriminant analysis (LDA) based data analysis method was developed for real-time tissue identification in a surgical environment. The method has been successfully tested on post-mortem and ex vivo human samples including astrocytomas, meningeomas, metastatic brain tumors, and healthy brain tissue.
A hybrid metaheuristic for the time-dependent vehicle routing problem with hard time windows
Directory of Open Access Journals (Sweden)
N. Rincon-Garcia
2017-01-01
Full Text Available This article paper presents a hybrid metaheuristic algorithm to solve the time-dependent vehicle routing problem with hard time windows. Time-dependent travel times are influenced by different congestion levels experienced throughout the day. Vehicle scheduling without consideration of congestion might lead to underestimation of travel times and consequently missed deliveries. The algorithm presented in this paper makes use of Large Neighbourhood Search approaches and Variable Neighbourhood Search techniques to guide the search. A first stage is specifically designed to reduce the number of vehicles required in a search space by the reduction of penalties generated by time-window violations with Large Neighbourhood Search procedures. A second stage minimises the travel distance and travel time in an ‘always feasible’ search space. Comparison of results with available test instances shows that the proposed algorithm is capable of obtaining a reduction in the number of vehicles (4.15%, travel distance (10.88% and travel time (12.00% compared to previous implementations in reasonable time.
New applications with time-dependent thermochemical simulation
Energy Technology Data Exchange (ETDEWEB)
Koukkari, P. [VTT Chemical Technology, Espoo (Finland); Laukkanen, L. [VTT Automation, Espoo (Finland); Penttilae, K. [Kemira Engineering Oy, Helsinki (Finland)
1996-12-31
A new method (RATEMIX) to calculate multicomponent chemical reaction mixtures as a series of sequential thermochemical states was recently introduced. The procedure combines multicomponent thermodynamics with chemical kinetics and may be used to simulate the multicomponent reactors as a thermochemical natural process. The method combines the desired reaction rates sequentially with constrained Gibbs energy minimization. The reactant concentrations are determined by the experimental (Arrhenius) rate laws. During the course of the given reaction the subsequent side reactions are supposed to occur reversibly. At every sequential stage of the given reaction the temperature and composition of the reaction mixture are calculated by a thermodynamic subroutine, which minimizes the Gibbs energy of the system and takes into account the heat transfer between the system and its surroundings. The extents of reaction are included as algorithmic constraints in the Gibbs energy minimization procedure. Initially, the reactants are introduced to the system as inert copies to match both the mass and energy balance of the reactive system. During the calculation the copies are sequentially interchanged to the actual reactants which allows one to simulate the time-dependent reaction route by using the thermochemical procedure. For each intermediate stage, the temperature and composition are calculated and as well numerical estimates of the thermodynamic functions are obtained. The method is applicable in processes where the core thermodynamic and kinetic data of the system are known and the time-dependent heat transfer data can either be measured or estimated by calculation. The method has been used to simulate e.g. high temperature flame reactions, zinc vapour oxidation and a counter-current rotary drum with chemical reactions. The procedure has today been tested with SOLGASMIX, CHEMSAGE and HSC programs. (author)
Time- and temperature-dependent failures of a bonded joint
Sihn, Sangwook
This dissertation summarizes my study of time- and temperature-dependent behavior of a tubular lap bonded joint to provide a design methodology for windmill blade structures. The bonded joint is between a cast-iron rod and a GFRP composite pipe. The adhesive material is an epoxy containing chopped glass fibers. We proposed a new fabrication method to make concentric and void-less specimens of the tubular joint with a thick adhesive bondline to stimulate the root bond of a blade. The thick bondline facilitates the joint assembly of actual blades. For a better understanding of the behavior of the bonded joint, we studied viscoelastic behavior of the adhesive materials by measuring creep compliance at several temperatures during loading period. We observed that the creep compliance depends highly on the period of loading and the temperature. We applied time-temperature equivalence to the creep compliance of the adhesive material to obtain time-temperature shift factors. We also performed constant-rate of monotonically increased uniaxial tensile tests to measure static strength of the tubular lap joint at several temperatures and different strain-rates. We observed two failure modes from load-deflection curves and failed specimens. One is the brittle mode, which was caused by weakness of the interfacial strength occurring at low temperature and short period of loading. The other is the ductile mode, which was caused by weakness of the adhesive material at high temperature and long period of loading. Transition from the brittle to the ductile mode appeared as the temperature or the loading period increased. We also performed tests under uniaxial tensile-tensile cyclic loadings to measure fatigue strength of the bonded joint at several temperatures, frequencies and stress ratios. The fatigue data are analyzed statistically by applying the residual strength degradation model to calculate statistical distribution of the fatigue life. Combining the time
Quantum Drude friction for time-dependent density functional theory
Neuhauser, Daniel; Lopata, Kenneth
2008-10-01
way to very simple finite grid description of scattering and multistage conductance using time-dependent density functional theory away from the linear regime, just as absorbing potentials and self-energies are useful for noninteracting systems and leads.
Time-dependent viscoelastic properties along rat small intestine
Institute of Scientific and Technical Information of China (English)
James B Smith; Jing-Bo Zhao; Yan-Ling Dou; Hans Gregersen
2005-01-01
AIM: To measure the time-dependent (viscoelastic)behavior in the change of the small intestinal opening angle and to test how well the behavior could be described by the Kelvin model for a standard linear solid.METHODS: Segments from the duodenum, jejunum, and ileum were harvested from 10 female Wistar rats and the luminal diameter, wall thickness, and opening angleover time (θ(t)) were measured from rings cut from thesesegments.RESULTS: Morphometric variations were found along thesmall intestine with an increase in luminal area and adecrease in wall thickness from the duodenum to theileum. The opening angle obtained after 60 min washighest in the duodenum (220.8±12.9°) and decreasedalong the length of the intestine to 143.9±8.9° in the jejunum and 151.4±9.4° in the ileum. The change ofopening angle as a function of time, fitted well to theKelvin model using the equation θ(t)/θo = [1-ηexp (-λt)]after the ring was cut. The computed creep rate λ did notdiffer between the segments. Compared to constantcalculated from pig aorta and coronary artery, it showedthat α agreed well (within 5%), η was three times largerthan that for vascular tissue, and λ ranged ±40% from the value of the pig coronary artery and was a third of the value of pig aorta.CONCLUSION: The change of opening angle over timefor all the small intestine segments fits well to the standardlinear spring-dashpot model. This viscoelastic constantof the rat small intestine is fairly homogenous along itslength. The data obtained from this study add to a baseset of biomechanical data on the small intestine andprovide a reference state for comparison to other tissues,diseased intestinal tissue or intestinal tissue exposed todrugs or chemicals.
Anurov, M V; Titkova, S M; Oettinger, A P
2012-04-01
We aimed to compare the effectiveness of experimental middle hernia defect repair in regard to the transverse and longitudinal positioning of anisotropic lightweight surgical mesh. The mechanical properties of fascial layers and surgical mesh DynaMesh(®)-PP Light were determined in two perpendicular directions under uniaxial tension. In 12 male Wistar rats, middle hernia defect was repaired by the sublay technique. In six animals, the mesh was positioned across (DLH group) and in the other six along (DLV group) the midline. At 6 months after implantation, mesh deformation, structural rearrangement, and repaired abdominal wall biomechanics were evaluated. Histological sections were stained with van Giesen and Mallory's trichrome. The anisotropic mechanical properties of the mesh and fascial layers coincided in the DLH group, but did not correspond to each other in the DLV group. In the DLV group, meshes were stretched in width by 11.4% and reduced in length by 12.7%. In all animals, the lower edge of the mesh was shifted to a defect area with margin hernia formation in two rats. Constant shear stress caused disproportional connective tissue formation. Repaired abdominal wall lost its natural elasticity. In the DLH group, the mesh deformation was minimal. Formed connective tissue was tightly associated with the anterior layer and did not differ from it in composition. The mechanical properties of repaired abdominal wall were close to those of the anterior layer. In prosthetic hernia repair, the mechanical properties of surgical mesh should correspond with those of the fascia being repaired. A mismatch of mechanical properties may result in implant deformation, abdominal wall biomechanics impairment, and recurrent herniation at the edges of the meshes.
Time matters: post-surgical recovery of gastric evacuation rate in Atlantic cod
DEFF Research Database (Denmark)
Behrens, Jane; Gräns, Albin; Andersen, Niels Gerner;
GER was affected after surgically introducing dummies of a blood-flow biotelemetry system into the abdominal cavity of Atlantic cod. Two days post surgery the cod with implants were, together with a control group, force-fed a standardized meal and the stomach contents recovered 24h later....... This procedure was repeated for both groups of fish after one additional week of recovery. After two days GER was significantly lower in the group of fish with surgical implants compared to the control group, but the difference was not maintained after one additional week of recovery. We conclude that 10 days...... of postsurgical recovery will stabilize GER in cod. The results indicate that the presence of the implant per se did not affect GER but that the effects observed came from surgery and/or postsurgical stress. 10 days should consequently be a starting point for future studies even if longer recovery periods...
Energy Technology Data Exchange (ETDEWEB)
Woodley, Christa M.; Wagner, Katie A.; Knox, Kasey M.
2012-01-31
The Juvenile Salmon Acoustic Telemetry System (JSATS) was developed for the U.S. Army Corp of Engineers Portland District (USACE) to address questions related to survival and performance measures of juvenile salmonids as they pass through the Federal Columbia River Power System (FCRPS). Researchers using JSATS acoustic transmitters (ATs) were tasked with standardizing the surgical implantation procedure to ensure that the stressors of handling and surgery on salmonids were consistent and less likely to cause effects of tagging in survival studies. Researchers questioned whether the exposure time in 'knockdown' anesthesia (or induction) to prepare fish for surgery could influence the survival of study fish (CBSPSC 2011). Currently, fish are held in knockdown anesthesia after they reach Stage 4 anesthesia until the completion of the surgical implantation of a transmitter, varies from 5 to 15 minutes for studies conducted in the Columbia Basin. The Columbia Basin Surgical Protocol Steering Committee (CBSPSC ) expressed concern that its currently recommended 10-minute maximum time limit during which fish are held in anesthetic - tricaine methanesulfonate (MS-222, 80 mg L-1 water) - could increase behavioral and physiological costs, and/or decrease survival of outmigrating juvenile salmonids. In addition, the variability in the time fish are held at Stage 4 could affect the data intended for direct comparison of fish within or among survival studies. Under the current recommended protocol, if fish exceed the 10-minute time limit, they are to be released without surgical implantation, thereby increasing the number of fish handled and endangered species 'take' at the bypass systems for FCRPS survival studies.
Miller, Bruce S.; Robbins, Christopher; Gagnier, Joel Joseph
2016-01-01
Objectives: The minimally important difference (MID) is the smallest change in an outcome measure that is perceived by patients as beneficial. The MIDs for the ASES and WORC scores have not been established in a homogenous population of patients with rotator cuff tears. The objective of the present study was to establish the MIDs for patients with known cuff tears who were treated both surgically and non-surgically, and to compare the MIDs over time. Methods: We included 209 subjects with known full-thickness rotator cuff tears who were followed prospectively for two years. The WORC and ASES scores were collected at baseline, 4, 8, 16, 32, and 48 weeks, 1 year and 2 years. At the final follow-up point patients filled out an end-of-study form which included questions regarding change in their condition after treatment. Results: For those that indicated being minimally better, the change from baseline for the ASES score was -20.57 (-2.94 to -38.20) and for the WORC was 418.60 (70.39 to 766.81); both indicated improvement in outcomes. When converted to the percentage change score the WORC change represented 19.93%. The plots of these new MID values for the ASES and WORC indicate that not only does the operative group improve more than the non-operative group but it does so to an extent that is greater than the MID. The non-operative group also improved across time, but the magnitude did not exceed the MID for either the WORC or the ASES. Conclusion: We found that the ASES and the WORC MIDs in patients with rotator cuff tears is different from that previously reported, and that the operative group change was greater than the non-operative group change. This information will directly improve our ability to: (1) Determine when patients with RCTs are changing in a meaningful manner; (2) Accurately power clinical studies using these outcome measures; (3) Make more informed choices of treatments in these patients. This is the first study to report MIDs for the ASES and WORC
New real-time MR image-guided surgical robotic system for minimally invasive precision surgery
Energy Technology Data Exchange (ETDEWEB)
Hashizume, M.; Yasunaga, T.; Konishi, K. [Kyushu University, Department of Advanced Medical Initiatives, Faculty of Medical Sciences, Fukuoka (Japan); Tanoue, K.; Ieiri, S. [Kyushu University Hospital, Department of Advanced Medicine and Innovative Technology, Fukuoka (Japan); Kishi, K. [Hitachi Ltd, Mechanical Engineering Research Laboratory, Hitachinaka-Shi, Ibaraki (Japan); Nakamoto, H. [Hitachi Medical Corporation, Application Development Office, Kashiwa-Shi, Chiba (Japan); Ikeda, D. [Mizuho Ikakogyo Co. Ltd, Tokyo (Japan); Sakuma, I. [The University of Tokyo, Graduate School of Engineering, Bunkyo-Ku, Tokyo (Japan); Fujie, M. [Waseda University, Graduate School of Science and Engineering, Shinjuku-Ku, Tokyo (Japan); Dohi, T. [The University of Tokyo, Graduate School of Information Science and Technology, Bunkyo-Ku, Tokyo (Japan)
2008-04-15
To investigate the usefulness of a newly developed magnetic resonance (MR) image-guided surgical robotic system for minimally invasive laparoscopic surgery. The system consists of MR image guidance [interactive scan control (ISC) imaging, three-dimensional (3-D) navigation, and preoperative planning], an MR-compatible operating table, and an MR-compatible master-slave surgical manipulator that can enter the MR gantry. Using this system, we performed in vivo experiments with MR image-guided laparoscopic puncture on three pigs. We used a mimic tumor made of agarose gel and with a diameter of approximately 2 cm. All procedures were successfully performed. The operator only advanced the probe along the guidance device of the manipulator, which was adjusted on the basis of the preoperative plan, and punctured the target while maintaining the operative field using robotic forceps. The position of the probe was monitored continuously with 3-D navigation and 2-D ISC images, as well as the MR-compatible laparoscope. The ISC image was updated every 4 s; no artifact was detected. A newly developed MR image-guided surgical robotic system is feasible for an operator to perform safe and precise minimally invasive procedures. (orig.)
Short- and Long- Time Transport Structures in a Three Dimensional Time Dependent Flow
Chabreyrie, Rodolphe
2014-01-01
Lagrangian transport structures for three-dimensional and time-dependent fluid flows are of great interest in numerous applications, particularly for geophysical or oceanic flows. In such flows, chaotic transport and mixing can play important environmental and ecological roles, for examples in pollution spills or plankton migration. In such flows, where simulations or observations are typically available only over a short time, understanding the difference between short-time and long-time transport structures is critical. In this paper, we use a set of classical (i.e. Poincar\\'e section, Lyapunov exponent) and alternative (i.e. finite time Lyapunov exponent, Lagrangian coherent structures) tools from dynamical systems theory that analyze chaotic transport both qualitatively and quantitatively. With this set of tools we are able to reveal, identify and highlight differences between short- and long-time transport structures inside a flow composed of a primary horizontal contra-rotating vortex chain, small later...
Density-functional perturbation theory goes time-dependent
Directory of Open Access Journals (Sweden)
Gebauer, Ralph
2008-05-01
Full Text Available The scope of time-dependent density-functional theory (TDDFT is limited to the lowest portion of the spectrum of rather small systems (a few tens of atoms at most. In the static regime, density-functional perturbation theory (DFPT allows one to calculate response functions of systems as large as currently dealt with in ground-state simulations. In this paper we present an effective way of combining DFPT with TDDFT. The dynamical polarizability is first expressed as an off-diagonal matrix element of the resolvent of the Kohn-Sham Liouvillian super-operator. A DFPT representation of response functions allows one to avoid the calculation of unoccupied Kohn-Sham orbitals. The resolvent of the Liouvillian is finally conveniently evaluated using a newly developed non-symmetric Lanczos technique, which allows for the calculation of the entire spectrum with a single Lanczos recursion chain. Each step of the chain essentially requires twice as many operations as a single step of the iterative diagonalization of the unperturbed Kohn-Sham Hamiltonian or, for that matter, as a single time step of a Car-Parrinello molecular dynamics run. The method will be illustrated with a few case molecular applications.
Time-dependent cavitation in a viscous fluid
Shneidman, Vitaly A.
2016-12-01
Kinetics of nucleation and growth of empty bubbles in a nonvolatile incompressible fluid under negative pressure is considered within the generalized Zeldovich framework. The transient matched asymptotic solution obtained earlier for predominantly viscous nucleation is used to evaluate the distribution of growing cavities over sizes. Inertial effects described by the Rayleigh-Plesset equation are further included. The distributions are used to estimate the volume occupied by cavities, which leads to increase of pressure and eventual self-quenching of nucleation. Numerical solutions are obtained and compared with analytics. Due to rapid expansion of cavities the conventional separation of the nucleation and the growth time scales can be less distinct, which increases the role of transient effects. In particular, in the case of dominant viscosity a typical power-law tail of the quasistationary distribution is replaced by a time-dependent exponential tail. For fluids of the glycerin type such distributions can extend into the micrometer region, while in low-viscosity liquids (water, mercury) exponential distributions are short lived and are restricted to nanometer scales due to inertial effects.
Time-dependent effect in green synthesis of silver nanoparticles
Directory of Open Access Journals (Sweden)
Darroudi M
2011-04-01
Full Text Available Majid Darroudi1,2, Mansor Bin Ahmad3, Reza Zamiri4, AK Zak5, Abdul Halim Abdullah1,3, Nor Azowa Ibrahim31Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology (ITMA, Universiti Putra Malaysia, Selangor, Malaysia; 2Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran; 3Department of Chemistry, 4Department of Physics, Faculty of Science, Universiti Putra Malaysia, Selangor, Malaysia; 5Low Dimensional Materials Research Center, Department of Physics, Faculty of Science, University of Malaya, Kuala Lumpur, MalaysiaAbstract: The application of “green” chemistry rules to nanoscience and nanotechnology is very important in the preparation of various nanomaterials. In this work, we successfully developed an eco-friendly chemistry method for preparing silver nanoparticles (Ag-NPs in natural polymeric media. The colloidal Ag-NPs were synthesized in an aqueous solution using silver nitrate, gelatin, and glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag-NPs were studied at different reaction times. The ultraviolet-visible (UV-vis spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM and their size distributions. The prepared samples were also characterized by X-ray diffraction (XRD and atomic force microscopy (AFM. The use of eco-friendly reagents, such as gelatin and glucose, provides green and economic attributes to this work.Keywords: silver nanoparticles, gelatin, green chemistry, time-dependent effect, ultraviolet-visible spectra
Time-dependent histamine release from stored human blood products
DEFF Research Database (Denmark)
Nielsen, Hans Jørgen; Edvardsen, L; Vangsgaard, K;
1996-01-01
storage. Whole blood (six units), plasma-reduced whole blood (six units), and plasma- and buffy coat-reduced (saline-adenine-glucose-mannitol) (SAGM) blood (six units) from unpaid healthy donors were stored in the blood bank for 35 days at 4 degrees C. Plasma histamine and total cell-bound histamine......Perioperative transfusion of whole blood has been shown to amplify trauma-induced immunosuppression, which could be attenuated by perioperative administration of histamine2 receptor antagonists. Supernatants from different blood products were, therefore, analysed for histamine content during.......0 (range 176.0-910.0) nmol/l in whole blood and 475.0 (range 360.0-1560.0) nmol/l in plasma-reduced whole blood, while it was undetectable in SAGM blood. Spontaneous histamine release increased in a time-dependent manner from a median of 6.7 (range 2.2-17.4) nmol/l at the time of storage to 175.0 (range 33...
Time-dependence of non-planar accretion discs
Energy Technology Data Exchange (ETDEWEB)
Papaloizou, J.C.B. (Queen Mary Coll., London (UK). Dept. of Applied Mathematics); Pringle, J.E. (Amsterdam Univ. (Netherlands). Astronomical Inst.)
1983-03-01
Equations are derived which describe the time-dependence of a viscous, tilted accretion disc subject to external torques. A full hydrodynamical treatment is used and the equations linearized in terms of a small tilt. It is shown that previous attempts at deriving these equations are inadequate due to the inconsistency of some of the assumptions made. The behaviour of a tilted viscous disc is not simple to describe. Viscous forces tend to flatten the disc, but they also produce torques within the disc which induce local precession of disc elements. The main complication is that the horizontal motions induced in the disc by the tilt are resonantly driven so that their magnitude and phase are governed by the viscosity. This leads to the disc being smoothed on a time-scale faster than the usual viscous one. In order to obtain a simple diffusion equation governing the tilt angle ..beta.., it is necessary in a Keplerian disc that the viscosity parameter ..cap alpha.. be greater than the opening angle of the disc (H/R). If this condition is not satisfied consideration must be given to the proper dynamical modes of the disc, and the simple approach to the problem adopted here is inadequate.
Charge transfer in time-dependent density functional theory
Maitra, Neepa T.
2017-10-01
Charge transfer plays a crucial role in many processes of interest in physics, chemistry, and bio-chemistry. In many applications the size of the systems involved calls for time-dependent density functional theory (TDDFT) to be used in their computational modeling, due to its unprecedented balance between accuracy and efficiency. However, although exact in principle, in practise approximations must be made for the exchange-correlation functional in this theory, and the standard functional approximations perform poorly for excitations which have a long-range charge-transfer component. Intense progress has been made in developing more sophisticated functionals for this problem, which we review. We point out an essential difference between the properties of the exchange-correlation kernel needed for an accurate description of charge-transfer between open-shell fragments and between closed-shell fragments. We then turn to charge-transfer dynamics, which, in contrast to the excitation problem, is a highly non-equilibrium, non-perturbative, process involving a transfer of one full electron in space. This turns out to be a much more challenging problem for TDDFT functionals. We describe dynamical step and peak features in the exact functional evolving over time, that are missing in the functionals currently used. The latter underestimate the amount of charge transferred and manifest a spurious shift in the charge transfer resonance position. We discuss some explicit examples.
Gap vortex streets and turbulence in time-dependent streams
Duong, Dan; Tavoularis, Stavros
2016-11-01
Gap vortex streets form in axial flows in highly eccentric annular channels, tightly packed rod bundles and other channels having narrow gap regions flanked by wider ones. The characteristics of these vortices and the flow and turbulence distributions in some of these channels have in the past documented for steady streams; in particular, the vortex generation frequency was found to be proportional to the bulk Reynolds number. The present study extends these findings to both accelerating and decelerating air flows in a large-scale rod bundle, configured as a wind tunnel with a by-pass branch equipped with a controlled movable flap just downstream of the blower. Time-dependent statistical properties in a gap and a subchannel centre were determined by phase-averaging velocity measurements collected with hot-wire anemometers and the time history of the phase-averaged vortex street frequency was determined with the use of a wavelet transform. Contrary to expectations, the results show that deviations of the vortex frequency and other flow characteristics from the corresponding values in steady flows at the same bulk Reynolds number were significant during acceleration and much less so during deceleration. Supported by the Natural Sciences and Engineering Research Council of Canada and the Canadian Nuclear Laboratories.
Hydration Dependence of Energy Relaxation Time for Cytochrome C
Ye, Shuji; Chen, Jing-Yin; Knab, Joseph R.; Markelz, Andrea
2006-03-01
Hydration plays a critical role in protein dynamics. Here we consider the effects of hydration on energy relaxation for an electronically excited heme protein cytochrome c. We measure the hydration dependence of energy relaxation time of cytochrome C films after photoexcitation in the Soret regionusing two-color pump/probe time resolved transmission measurements. Thin films were prepared from cytochrome C/ Trizma buffer solutions and mounted in a hydration controlled cell. We used 400nm (˜3 mW) to pump the B band and 800 nm (˜1 mW) to probe the III band. The III band corresponds to the charge-transfer transition between heme π and iron d orbital, and is assigned to the ground electronic state of the heme. Therefore this band can be used to probe the ground state population. Three separate dynamic components were observed: a very fast transient τ1 ˜ 200 fs; a several hundred femtosecond component (τ2); and a recovery of the ground state absorption(τ3). We find τ3 apparently decreases with decreasing hydration while τ1 and τ2 are independent of hydration.
Riccati and Ermakov Equations in Time-Dependent and Time-Independent Quantum Systems
Directory of Open Access Journals (Sweden)
Dieter Schuch
2008-05-01
Full Text Available The time-evolution of the maximum and the width of exact analytic wave packet (WP solutions of the time-dependent Schrödinger equation (SE represents the particle and wave aspects, respectively, of the quantum system. The dynamics of the maximum, located at the mean value of position, is governed by the Newtonian equation of the corresponding classical problem. The width, which is directly proportional to the position uncertainty, obeys a complex nonlinear Riccati equation which can be transformed into a real nonlinear Ermakov equation. The coupled pair of these equations yields a dynamical invariant which plays a key role in our investigation. It can be expressed in terms of a complex variable that linearizes the Riccati equation. This variable also provides the time-dependent parameters that characterize the Green's function, or Feynman kernel, of the corresponding problem. From there, also the relation between the classical and quantum dynamics of the systems can be obtained. Furthermore, the close connection between the Ermakov invariant and the Wigner function will be shown. Factorization of the dynamical invariant allows for comparison with creation/annihilation operators and supersymmetry where the partner potentials fulfil (real Riccati equations. This provides the link to a nonlinear formulation of time-independent quantum mechanics in terms of an Ermakov equation for the amplitude of the stationary state wave functions combined with a conservation law. Comparison with SUSY and the time-dependent problems concludes our analysis.
Probing Time-Dependent Molecular Dipoles on the Attosecond Time Scale
Neidel, Ch.; Klei, J.; Yang, C.-H.; Rouzée, A.; Vrakking, M. J. J.; Klünder, K.; Miranda, M.; Arnold, C. L.; Fordell, T.; L'Huillier, A.; Gisselbrecht, M.; Johnsson, P.; Dinh, M. P.; Suraud, E.; Reinhard, P.-G.; Despré, V.; Marques, M. A. L.; Lépine, F.
2013-07-01
Photoinduced molecular processes start with the interaction of the instantaneous electric field of the incident light with the electronic degrees of freedom. This early attosecond electronic motion impacts the fate of the photoinduced reactions. We report the first observation of attosecond time scale electron dynamics in a series of small- and medium-sized neutral molecules (N2, CO2, and C2H4), monitoring time-dependent variations of the parent molecular ion yield in the ionization by an attosecond pulse, and thereby probing the time-dependent dipole induced by a moderately strong near-infrared laser field. This approach can be generalized to other molecular species and may be regarded as a first example of molecular attosecond Stark spectroscopy.
Solving the time dependent vehicle routing problem by metaheuristic algorithms
Johar, Farhana; Potts, Chris; Bennell, Julia
2015-02-01
The problem we consider in this study is Time Dependent Vehicle Routing Problem (TDVRP) which has been categorized as non-classical VRP. It is motivated by the fact that multinational companies are currently not only manufacturing the demanded products but also distributing them to the customer location. This implies an efficient synchronization of production and distribution activities. Hence, this study will look into the routing of vehicles which departs from the depot at varies time due to the variation in manufacturing process. We consider a single production line where demanded products are being process one at a time once orders have been received from the customers. It is assumed that order released from the production line will be loaded into scheduled vehicle which ready to be delivered. However, the delivery could only be done once all orders scheduled in the vehicle have been released from the production line. Therefore, there could be lateness on the delivery process from awaiting all customers' order of the route to be released. Our objective is to determine a schedule for vehicle routing that minimizes the solution cost including the travelling and tardiness cost. A mathematical formulation is developed to represent the problem and will be solved by two metaheuristics; Variable Neighborhood Search (VNS) and Tabu Search (TS). These algorithms will be coded in C ++ programming and run using 56's Solomon instances with some modification. The outcome of this experiment can be interpreted as the quality criteria of the different approximation methods. The comparison done shown that VNS gave the better results while consuming reasonable computational efforts.
Time-dependent CP violation in B decays at Belle
Santelj, Luka
2013-01-01
Using the full data sample collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider, we present three recent measurements of time-dependent CP violation in $B$ decays, and a measurement of branching fraction of the $B^0\\to\\rho^0\\rho^0$ decay. We studied $B\\to\\omega K$ decays and measured the values of CP violation parameters in $B^0\\to\\omega K^0_S$ to be $A_{\\omega K^0_S} =-0.36\\pm 0.19(stat)\\pm 0.05(syst)$ and $S_{\\omega K^0_S}= +0.91\\pm 0.32 \\pm 0.05 $, which gives the first evidence of CP violation in this decay. In addition, we measured the direct CP violation in $B^+\\to\\omega K^+$ to be $A_{CP} (B^+ \\to \\omega K^+)=-0.03\\pm 0.04 \\pm 0.01$, and two branching fractions $B(B^0 \\to \\omega K^0)=(4.5\\pm 0.4\\pm 0.3) \\times 10^{-6}$ and $B(B^+ \\to \\omega K^+)=(6.8\\pm 0.4 \\pm 0.4) \\times 10^{-6}$ (preliminary). From the measurement of CP violation parameters in the $B^0\\to\\eta'K^0$ decay we obtain $S_{\\eta'K^0} = 0.68 \\pm 0.07\\pm 0.03$ and $A_{\\eta'K^0} = +0.03 \\pm 0.05\\pm 0.04$ (prelimin...
A history of spike-timing-dependent plasticity
Directory of Open Access Journals (Sweden)
Henry eMarkram
2011-08-01
Full Text Available How learning and memory is achieved in the brain is a central question in neuroscience research. Key to today’s research into information storage in the brain is the concept of synaptic plasticity, a notion that has been heavily influenced by Donald Hebb’s 1949 postulate. Hebb conjectured that repeatedly and persistently coactive cells should increase connective strength among populations of interconnected neurons as a means of storing a memory trace, also known as an engram. Hebb certainly was not the first to make such a conjecture, as we show in this history. Nevertheless, literally thousands of studies into the classical frequency-dependent paradigm of cellular learning rules were directly inspired by the Hebbian postulate. But in more recent years, a novel concept in cellular learning has emerged, where temporal order instead of frequency is emphasized. This new learning paradigm — known as Spike-Timing-Dependent Plasticity, or STDP — has rapidly gained tremendous interest, perhaps because of its combination of elegant simplicity, biological plausibility, and computational power. But what are the roots of today’s STDP concept? Here, we discuss several centuries of diverse thinking, beginning with philosophers such as Aristotle, Locke and Ribot, traversing e.g. Lugaro’s plasticità and Rosenblatt’s Perceptron, and culminating with the discovery of STDP. We highlight interactions between theoretical and experimental fields, showing how discoveries sometimes occurred in parallel, seemingly without much knowledge of the other field, and sometimes via concrete back-and-forth communication. We point out where the future directions may lie, which includes interneuron STDP, the functional impact of STDP, its mechanisms and its neuromodulatory regulation, and the linking of STDP to the developmental formation and continuous plasticity of neuronal networks.
DEFF Research Database (Denmark)
Azarmehr, Iman; Stokbro, Kasper; Bell, R. Bryan
2017-01-01
were identified in the field of traumatology. Treatment of complex orbital fractures was considerably improved by the use of SN compared with traditionally treated control groups. Conclusions: SN seems to be a very promising addition to the surgical toolkit. Planning details of the surgical procedure...... in a 3-dimensional virtual environment and execution with real-time guidance can significantly improve precision. Among factors to be considered are the financial investments necessary and the learning curve....
Eliyas, S; Vere, J; Ali, Z; Harris, I
2014-02-01
Non-surgical endodontic retreatment is the treatment of choice for endodontically treated teeth with recurrent or residual disease in the majority of cases. In some cases, surgical endodontic treatment is indicated. Successful micro-surgical endodontic treatment depends on the accuracy of diagnosis, appropriate case selection, the quality of the surgical skills, and the application of the most appropriate haemostatic agents and biomaterials. This article describes the armamentarium and technical procedures involved in performing micro-surgical endodontics to a high standard.
Prandtl-Ishlinskii hysteresis models for complex time dependent hysteresis nonlinearities
Al Janaideh, M.; Krejčí, P
2012-01-01
We introduce a new class of time dependent hysteresis models by combining the time dependent Prandtl–Ishlinskii model with functional nonlinearities. This combination improves the capability of the time dependent Prandtl–Ishlinskii model to characterize a class of complex time dependent hysteresis nonlinearities in smart actuators. The analytical inversion for the proposed time dependent hysteresis model is also presented in order to extend the inversion algorithm of the inverse time dependen...
Spike-timing dependent plasticity and the cognitive map
Directory of Open Access Journals (Sweden)
Daniel eBush
2010-10-01
Full Text Available Since the discovery of place cells – single pyramidal neurons that encode spatial location – it has been hypothesised that the hippocampus may act as a cognitive map of known environments. This putative function has been extensively modelled using auto-associative networks, which utilise rate-coded synaptic plasticity rules in order to generate strong bi-directional connections between concurrently active place cells that encode for neighbouring place fields. However, empirical studies using hippocampal cultures have demonstrated that the magnitude and direction of changes in synaptic strength can also be dictated by the relative timing of pre- and post- synaptic firing according to a spike-timing dependent plasticity (STDP rule. Furthermore, electrophysiology studies have identified persistent ‘theta-coded’ temporal correlations in place cell activity in vivo, characterised by phase precession of firing as the corresponding place field is traversed. It is not yet clear if STDP and theta-coded neural dynamics are compatible with cognitive map theory and previous rate-coded models of spatial learning in the hippocampus. Here, we demonstrate that an STDP rule based on empirical data obtained from the hippocampus can mediate rate-coded Hebbian learning when pre- and post- synaptic activity is stochastic and has no persistent sequence bias. We subsequently demonstrate that a spiking recurrent neural network that utilises this STDP rule, alongside theta-coded neural activity, allows the rapid development of a cognitive map during directed or random exploration of an environment of overlapping place fields. Hence, we establish that STDP and phase precession are compatible with rate-coded models of cognitive map development.
Modeling and Correcting the Time-Dependent ACS PSF
Rhodes, Jason; Massey, Richard; Albert, Justin; Taylor, James E.; Koekemoer, Anton M.; Leauthaud, Alexie
2006-01-01
The ability to accurately measure the shapes of faint objects in images taken with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST) depends upon detailed knowledge of the Point Spread Function (PSF). We show that thermal fluctuations cause the PSF of the ACS Wide Field Camera (WFC) to vary over time. We describe a modified version of the TinyTim PSF modeling software to create artificial grids of stars across the ACS field of view at a range of telescope focus values. These models closely resemble the stars in real ACS images. Using 10 bright stars in a real image, we have been able to measure HST s apparent focus at the time of the exposure. TinyTim can then be used to model the PSF at any position on the ACS field of view. This obviates the need for images of dense stellar fields at different focus values, or interpolation between the few observed stars. We show that residual differences between our TinyTim models and real data are likely due to the effects of Charge Transfer Efficiency (CTE) degradation. Furthermore, we discuss stochastic noise that is added to the shape of point sources when distortion is removed, and we present MultiDrizzle parameters that are optimal for weak lensing science. Specifically, we find that reducing the MultiDrizzle output pixel scale and choosing a Gaussian kernel significantly stabilizes the resulting PSF after image combination, while still eliminating cosmic rays/bad pixels, and correcting the large geometric distortion in the ACS. We discuss future plans, which include more detailed study of the effects of CTE degradation on object shapes and releasing our TinyTim models to the astronomical community.
Time Dependent Hadronic Modeling of Flat Spectrum Radio Quasars
Diltz, Christopher; Fossati, Giovanni
2015-01-01
We introduce a new time-dependent lepto-hadronic model for blazar emission that takes into account the radiation emitted by secondary particles, such as pions and muons, from photo hadronic interactions. Starting from a baseline parameter set guided by a fit to the spectral energy distribution of the blazar 3C 279, we perform a parameter study to investigate the effects of perturbations of the input parameters to mimic different flaring events to study the resulting lightcurves in the optical, X-ray, high energy (HE: E > 100 MeV) and very-high-energy (VHE: E > 100 GeV) gamma-rays as well as the neutrino emission associated with charged-pion and muon decay. We find that flaring events from an increase in the efficiency of Fermi II acceleration will produce a positive correlation between all bandpasses and a marked plateau in the HE gamma-ray lightcurve. We also predict a distinctive dip in the HE lightcurve for perturbations caused by a change in the proton injection spectral index. These plateaus / dips could...
Scene Context Dependency of Pattern Constancy of Time Series Imagery
Woodell, Glenn A.; Jobson, Daniel J.; Rahman, Zia-ur
2008-01-01
A fundamental element of future generic pattern recognition technology is the ability to extract similar patterns for the same scene despite wide ranging extraneous variables, including lighting, turbidity, sensor exposure variations, and signal noise. In the process of demonstrating pattern constancy of this kind for retinex/visual servo (RVS) image enhancement processing, we found that the pattern constancy performance depended somewhat on scene content. Most notably, the scene topography and, in particular, the scale and extent of the topography in an image, affects the pattern constancy the most. This paper will explore these effects in more depth and present experimental data from several time series tests. These results further quantify the impact of topography on pattern constancy. Despite this residual inconstancy, the results of overall pattern constancy testing support the idea that RVS image processing can be a universal front-end for generic visual pattern recognition. While the effects on pattern constancy were significant, the RVS processing still does achieve a high degree of pattern constancy over a wide spectrum of scene content diversity, and wide ranging extraneousness variations in lighting, turbidity, and sensor exposure.
Interpreting the Dependence of Mutation Rates on Age and Time.
Directory of Open Access Journals (Sweden)
Ziyue Gao
2016-01-01
Full Text Available Mutations can originate from the chance misincorporation of nucleotides during DNA replication or from DNA lesions that arise between replication cycles and are not repaired correctly. We introduce a model that relates the source of mutations to their accumulation with cell divisions, providing a framework for understanding how mutation rates depend on sex, age, and cell division rate. We show that the accrual of mutations should track cell divisions not only when mutations are replicative in origin but also when they are non-replicative and repaired efficiently. One implication is that observations from diverse fields that to date have been interpreted as pointing to a replicative origin of most mutations could instead reflect the accumulation of mutations arising from endogenous reactions or exogenous mutagens. We further find that only mutations that arise from inefficiently repaired lesions will accrue according to absolute time; thus, unless life history traits co-vary, the phylogenetic "molecular clock" should not be expected to run steadily across species.
Energy-Dependent Timing of Thermal Emission in Solar Flares
Jain, Rajmal; Rajpurohit, Arvind Singh; Aschwanden, Markus J; 10.1007/s11207-011-9754-1
2011-01-01
We report solar flare plasma to be multi-thermal in nature based on the theoretical model and study of the energy-dependent timing of thermal emission in ten M-class flares. We employ high-resolution X-ray spectra observed by the Si detector of the "Solar X-ray Spectrometer" (SOXS). The SOXS onboard the Indian GSAT-2 spacecraft was launched by the GSLV-D2 rocket on 8 May 2003. Firstly we model the spectral evolution of the X-ray line and continuum emission flux F(\\epsilon) from the flare by integrating a series of isothermal plasma flux. We find that multi-temperature integrated flux F(\\epsilon) is a power-law function of \\epsilon with a spectral index (\\gamma) \\approx -4.65. Next, based on spectral-temporal evolution of the flares we find that the emission in the energy range E= 4 - 15 keV is dominated by temperatures of T= 12 - 50 MK, while the multi-thermal power-law DEM index (\\gamma) varies in the range of -4.4 and -5.7. The temporal evolution of the X-ray flux F(\\epsilon,t) assuming a multi-temperature ...
Experimental quantum cosmology in time-dependent optical media
Westerberg, N; Belgiorno, F; Piazza, F Dalla; Faccio, D
2014-01-01
It is possible to construct artificial spacetime geometries for light by using intense laser pulses that modify the spatiotemporal properties of an optical medium. Here we theoretically investigate experimental possibilities for studying spacetime metrics of the form $\\textrm{d}s^2=c^2\\textrm{d}t^2-\\eta(t)^2\\textrm{d}x^2$. By tailoring the laser pulse shape and medium properties, it is possible to create a refractive index variation $n=n(t)$ that can be identified with $\\eta(t)$. Starting from a perturbative solution to a generalised Hopfield model for the medium described by an $n=n(t)$ we provide estimates for the number of photons generated by the time-dependent spacetime. The simplest example is that of a uniformly varying $\\eta(t)$ that therefore describes the Robertson-Walker metric, i.e. a cosmological expansion. The number of photon pairs generated in experimentally feasible conditions appears to be extremely small. However, large photon production can be obtained by periodically modulating the medium...
Recovery of time-dependent volatility in option pricing model
Deng, Zui-Cha; Hon, Y. C.; Isakov, V.
2016-11-01
In this paper we investigate an inverse problem of determining the time-dependent volatility from observed market prices of options with different strikes. Due to the non linearity and sparsity of observations, an analytical solution to the problem is generally not available. Numerical approximation is also difficult to obtain using most of the existing numerical algorithms. Based on our recent theoretical results, we apply the linearisation technique to convert the problem into an inverse source problem from which recovery of the unknown volatility function can be achieved. Two kinds of strategies, namely, the integral equation method and the Landweber iterations, are adopted to obtain the stable numerical solution to the inverse problem. Both theoretical analysis and numerical examples confirm that the proposed approaches are effective. The work described in this paper was partially supported by a grant from the Research Grant Council of the Hong Kong Special Administrative Region (Project No. CityU 101112) and grants from the NNSF of China (Nos. 11261029, 11461039), and NSF grants DMS 10-08902 and 15-14886 and by Emylou Keith and Betty Dutcher Distinguished Professorship at the Wichita State University (USA).
Local Time-Dependent Charging in a Perovskite Solar Cell.
Bergmann, Victor W; Guo, Yunlong; Tanaka, Hideyuki; Hermes, Ilka M; Li, Dan; Klasen, Alexander; Bretschneider, Simon A; Nakamura, Eiichi; Berger, Rüdiger; Weber, Stefan A L
2016-08-03
Efficient charge extraction within solar cells explicitly depends on the optimization of the internal interfaces. Potential barriers, unbalanced charge extraction, and interfacial trap states can prevent cells from reaching high power conversion efficiencies. In the case of perovskite solar cells, slow processes happening on time scales of seconds cause hysteresis in the current-voltage characteristics. In this work, we localized and investigated these slow processes using frequency-modulation Kelvin probe force microscopy (FM-KPFM) on cross sections of planar methylammonium lead iodide (MAPI) perovskite solar cells. FM-KPFM can map the charge density distribution and its dynamics at internal interfaces. Upon illumination, space charge layers formed at the interfaces of the selective contacts with the MAPI layer within several seconds. We observed distinct differences in the charging dynamics at the interfaces of MAPI with adjacent layers. Our results indicate that more than one process is involved in hysteresis. This finding is in agreement with recent simulation studies claiming that a combination of ion migration and interfacial trap states causes the hysteresis in perovskite solar cells. Such differences in the charging rates at different interfaces cannot be separated by conventional device measurements.
Stochastic Time-Dependent Current-Density Functional Theory
D'Agosta, Roberto
2008-03-01
Static and dynamical density functional methods have been applied with a certain degree of success to a variety of closed quantum mechanical systems, i.e., systems that can be described via a Hamiltonian dynamics. However, the relevance of open quantum systems - those coupled to external environments, e.g., baths or reservoirs - cannot be overestimated. To investigate open quantum systems with DFT methods we have introduced a new theory, we have named Stochastic Time-Dependent Current Density Functional theory (S-TDCDFT) [1]: starting from a suitable description of the system dynamics via a stochastic Schrödinger equation [2], we have proven that given an initial quantum state and the coupling between the system and the environment, there is a one-to-one correspondence between the ensemble-averaged current density and the external vector potential applied to the system.In this talk, I will introduce the stochastic formalism needed for the description of open quantum systems, discuss in details the theorem of Stochastic TD-CDFT, and provide few examples of its applicability like the dissipative dynamics of excited systems, quantum-measurement theory and other applications relevant to charge and energy transport in nanoscale systems.[1] M. Di Ventra and R. D'Agosta, Physical Review Letters 98, 226403 (2007)[2] N.G. van Kampen, Stochastic processes in Physics and Chemistry, (North Holland, 2001), 2nd ed.
Simple preconditioning for time-dependent density functional perturbation theory
Lehtovaara, Lauri; Marques, Miguel A. L.
2011-07-01
By far, the most common use of time-dependent density functional theory is in the linear-reponse regime, where it provides information about electronic excitations. Ideally, the linear-response equations should be solved by a method that avoids the use of the unoccupied Kohn-Sham states — such as the Sternheimer method — as this reduces the complexity and increases the precision of the calculation. However, the Sternheimer equation becomes ill-conditioned near and indefinite above the first resonant frequency, seriously hindering the use of efficient iterative solution methods. To overcome this serious limitation, and to improve the general convergence properties of the iterative techniques, we propose a simple preconditioning strategy. In our method, the Sternheimer equation is solved directly as a linear equation using an iterative Krylov subspace method, i.e., no self-consistent cycle is required. Furthermore, the preconditioner uses the information of just a few unoccupied states and requires simple and minimal modifications to existing implementations. In this way, convergence can be reached faster and in a considerably wider frequency range than the traditional approach.
Directory of Open Access Journals (Sweden)
Alexander M Aiken
Full Text Available INTRODUCTION: In low-income countries, Surgical Site Infection (SSI is a common form of hospital-acquired infection. Antibiotic prophylaxis is an effective method of preventing these infections, if given immediately before the start of surgery. Although several studies in Africa have compared pre-operative versus post-operative prophylaxis, there are no studies describing the implementation of policies to improve prescribing of surgical antibiotic prophylaxis in African hospitals. METHODS: We conducted SSI surveillance at a typical Government hospital in Kenya over a 16 month period between August 2010 and December 2011, using standard definitions of SSI and the extent of contamination of surgical wounds. As an intervention, we developed a hospital policy that advised pre-operative antibiotic prophylaxis and discouraged extended post-operative antibiotics use. We measured process, outcome and balancing effects of this intervention in using an interrupted time series design. RESULTS: From a starting point of near-exclusive post-operative antibiotic use, after policy introduction in February 2011 there was rapid adoption of the use of pre-operative antibiotic prophylaxis (60% of operations at 1 week; 98% at 6 weeks and a substantial decrease in the use of post-operative antibiotics (40% of operations at 1 week; 10% at 6 weeks in Clean and Clean-Contaminated surgery. There was no immediate step-change in risk of SSI, but overall, there appeared to be a moderate reduction in the risk of superficial SSI across all levels of wound contamination. There were marked reductions in the costs associated with antibiotic use, the number of intravenous injections performed and nursing time spent administering these. CONCLUSION: Implementation of a locally developed policy regarding surgical antibiotic prophylaxis is an achievable quality improvement target for hospitals in low-income countries, and can lead to substantial benefits for individual patients and
A matter of time! : time dependent mating decisions in the common lizard, zootoca vivipara
Breedveld, M. C.
2015-01-01
Life-history theory predicts that reproductive traits and behavioral strategies displayed by an organism should vary strategically with respect to the intrinsic and extrinsic conditions it is exposed to. Condition-dependent strategies may allow an individual to enhance its reproductive success, a crucial component of Darwinian fitness. Such strategies are predicted to vary with mate availability and the time of mate encounter, which may determine Darwinian fitness, especially in species where...
On the time-dependent extra spatial dimensions in six dimensional space-time
Lien, Phan Hong; Hai, Do Thi Hong
2016-06-01
In this paper, we analyze the time-dependent extra spatial dimensions in six dimensional (6D) space-time. The 4-brane is assumed to be a de Sitter space. Based on the form of the brane-world energy-momentum tensor proposed by Shiromizu et al. and the five dimensions by Peter K. F. Kuhfittic, we extended the theory to the 2-codimension embedded in higher dimensions. The inflation scenario in 6D is investigated in two cases of cosmological constant: Ʌ > 0 and Ʌ < 0. The energy of two extra dimensions is calculated too.
Parallelizing across time when solving time-dependent partial differential equations
Energy Technology Data Exchange (ETDEWEB)
Worley, P.H.
1991-09-01
The standard numerical algorithms for solving time-dependent partial differential equations (PDEs) are inherently sequential in the time direction. This paper describes algorithms for the time-accurate solution of certain classes of linear hyperbolic and parabolic PDEs that can be parallelized in both time and space and have serial complexities that are proportional to the serial complexities of the best known algorithms. The algorithms for parabolic PDEs are variants of the waveform relaxation multigrid method (WFMG) of Lubich and Ostermann where the scalar ordinary differential equations (ODEs) that make up the kernel of WFMG are solved using a cyclic reduction type algorithm. The algorithms for hyperbolic PDEs use the cyclic reduction algorithm to solve ODEs along characteristics. 43 refs.
Time-dependent viscometry study of endoglucanase action on xyloglucan: A real-time approach.
Spier, Vivian Cristina; Sierakowski, Maria Rita; Ibrahim, Amid Tony; Scholze Baum, Jéssica C; Silveira, Joana Lea M; de Freitas, Rilton Alves
2015-11-01
Hydrolysis of xyloglucan from Tamarindus indica and Hymenaea courbaril seeds with endoglucanase (EGII), which randomly breaks the (1→4)-linked β-glycosidic bonds of the polymer chain, was monitored in real time using time-dependent viscometry analysis (TDV). For both samples there was a decrease in the intrinsic viscosity ([η]), viscosity average molar mass (Mv), radius de gyration (Rg) and persistence length (Lp) immediately after the addition of the enzyme. It was observed the formation of oligosaccharides and oligomers composed of ∼2 units, up to 140min. Galactose-containing side chains two positions away from the non-substituted glucose, modulated the action of EGII, and the complete hydrolysis of the XG oligomers occurred after 24h. The results demonstrate for the first time the real-time degradation of xyloglucan as well the macromolecular and oligosaccharide composition during the EGII hydrolysis process.
An Iterative Time Windowed Signature Algorithm for Time Dependent Transcription Module Discovery.
Meng, Jia; Gao, Shou-Jiang; Huang, Yufei
2008-01-01
An algorithm for the discovery of time varying modules using genome-wide expression data is present here. When applied to large-scale time serious data, our method is designed to discover not only the transcription modules but also their timing information, which is rarely annotated by the existing approaches. Rather than assuming commonly defined time constant transcription modules, a module is depicted as a set of genes that are co-regulated during a specific period of time, i.e., a time dependent transcription module (TDTM). A rigorous mathematical definition of TDTM is provided, which is serve as an objective function for retrieving modules. Based on the definition, an effective signature algorithm is proposed that iteratively searches the transcription modules from the time series data. The proposed method was tested on the simulated systems and applied to the human time series microarray data during Kaposi's sarcoma-associated herpesvirus (KSHV) infection. The result has been verified by Expression Analysis Systematic Explorer.
Short- and Long- Time Transport Structures in a Three Dimensional Time Dependent Flow
Chabreyrie, Rodolphe; Llewellyn Smith, Stefan
2012-11-01
Lagrangian transport structures for three-dimensional and time-dependent fluid flows are of great interest in numerous applications, particularly for geophysical or oceanic flows. In such flows, chaotic transport and mixing can play important environmental and ecological roles, for examples in pollution spills or plankton migration. In such flows, where simulations or observations are typically available only over a short time, understanding the difference between short-time and long-time transport structures is critical. In this talk, we use a set of classical (i.e. Poincaré section, Lyapunov exponent) and alternative (i.e. finite time Lyapunov exponent, Lagrangian coherent structures) tools from dynamical systems theory that analyze chaotic transport both qualitatively and quantitatively. With this set of tools we are able to reveal, identify and highlight differences between short- and long-time transport structures inside a flow composed of a primary horizontal contra-rotating vortex chain, small lateral oscillations and a weak Ekman pumping. The difference is mainly the existence of regular or extremely slowly developing chaotic regions that are only present at short time. This research was funded by the ONR MURI Dynamical Systems Theory and Lagrangian Data Assimilation in 3D+1 Geophysical Fluid Dynamics.
Energy Technology Data Exchange (ETDEWEB)
Lofgren, E.V. [Science Applications International Corp., Fairfax Station, VA (United States); Uryasev, S.; Samanta, P. [Brookhaven National Lab., Upton, NY (United States)
1997-03-01
The unavailability of standby safety system components due to failures in nuclear power plants is considered to involve a time independent and a time dependent part. The former relates to the component`s unavailability from demand stresses due to usage, and the latter represents the component`s unavailability due to standby time stresses related to the environment. In this paper, data from the nuclear plant reliability data system (NPRDS) were used to partition the component`s unavailability into the contributions from standby time stress (i.e., due to environmental factors) and demand stress (i.e., due to usage). Analyses are presented of motor operated valves (MOVs), motor driven pumps (MDPs), and turbine driven pumps (FDPs). MOVs fail predominantly (approx. 78%) from environmental factors (standby time stress failures). MDPs fail slightly more frequently from demand stresses (approx. 63%) than standby time stresses, while TDPs fail predominantly from standby time stresses (approx. 78%). Such partitions of component unavailability have many uses in risk informed and performance based regulation relating to modifications to Technical Specification, in-service testing, precise determination of dominant accident sequences, and implementation of maintenance rules.
Energy Technology Data Exchange (ETDEWEB)
Lofgren, E.V. [Science Applications International Corp., Fairfax Station, VA (United States); Uryasev, S.; Samanta, P. [Brookhaven National Lab., Upton, NY (United States)
1997-02-01
The unavailability of standby safety system components due to failures in nuclear power plants is considered to involve a time-independent and a time-dependent part. The former relates to the component`s unavailability from demand stresses due to usage, and the latter represents the component`s unavailability due to standby-time stresses related to the environment. In this paper, data from the nuclear plant reliability data system (NPRDS) were used to partition the component`s unavailability into the contributions from standby-time stress (i.e., due to environmental factors) and demand stress (i.e., due to usage). Analyses are presented of motor-operated valves (MOVs), motor-driven pumps (MDPs), and turbine-driven pumps (TDPs). MOVs fail predominantly (approx. 78 %) from environmental factors (standby-time stress failures). MDPs fail slightly more frequently from demand stresses (approx. 63 %) than standby-time stresses, while TDPs fail predominantly from standby-time stresses (approx. 78 %). Such partitions of component unavailability have many uses in risk-informed and performance-based regulation relating to modifications to Technical Specification, in-service testing, precise determination of dominant accident sequences, and implementation of maintenance rules.
Passive markers for tracking surgical instruments in real-time 3-D ultrasound imaging.
Stoll, Jeffrey; Ren, Hongliang; Dupont, Pierre E
2012-03-01
A family of passive echogenic markers is presented by which the position and orientation of a surgical instrument can be determined in a 3-D ultrasound volume, using simple image processing. Markers are attached near the distal end of the instrument so that they appear in the ultrasound volume along with the instrument tip. They are detected and measured within the ultrasound image, thus requiring no external tracking device. This approach facilitates imaging instruments and tissue simultaneously in ultrasound-guided interventions. Marker-based estimates of instrument pose can be used in augmented reality displays or for image-based servoing. Design principles for marker shapes are presented that ensure imaging system and measurement uniqueness constraints are met. An error analysis is included that can be used to guide marker design and which also establishes a lower bound on measurement uncertainty. Finally, examples of marker measurement and tracking algorithms are presented along with experimental validation of the concepts.
Huang, Y X
2014-01-01
In the marine environment, many fields have fluctuations over a large range of different spatial and temporal scales. These quantities can be nonlinear \\red{and} non-stationary, and often interact with each other. A good method to study the multiple scale dynamics of such time series, and their correlations, is needed. In this paper an application of an empirical mode decomposition based time dependent intrinsic correlation, \\red{of} two coastal oceanic time series, temperature and dissolved oxygen (saturation percentage) is presented. The two time series are recorded every 20 minutes \\red{for} 7 years, from 2004 to 2011. The application of the Empirical Mode Decomposition on such time series is illustrated, and the power spectra of the time series are estimated using the Hilbert transform (Hilbert spectral analysis). Power-law regimes are found with slopes of 1.33 for dissolved oxygen and 1.68 for temperature at high frequencies (between 1.2 and 12 hours) \\red{with} both close to 1.9 for lower frequencies (t...
Valsangkar, Nakul P; Eppstein, Andrew C; Lawson, Rick A; Taylor, Amber N
2017-01-01
There are an increasing number of veterans in the United States, and the current delay and wait times prevent Veterans Affairs institutions from fully meeting the needs of current and former service members. Concrete strategies to improve throughput at these facilities have been sparse. To identify whether lean processes can be used to improve wait times for surgical procedures in Veterans Affairs hospitals. Databases in the Veterans Integrated Service Network 11 Data Warehouse, Veterans Health Administration Support Service Center, and Veterans Information Systems and Technology Architecture/Dynamic Host Configuration Protocol were queried to assess changes in wait times for elective general surgical procedures and clinical volume before, during, and after implementation of lean processes over 3 fiscal years (FYs) at a tertiary care Veterans Affairs medical center. All patients evaluated by the general surgery department through outpatient clinics, clinical video teleconferencing, and e-consultations from October 2011 through September 2014 were included. Patients evaluated through the emergency department or as inpatient consults were excluded. The surgery service and systems redesign service held a value stream analysis in FY 2013, culminating in multiple rapid process improvement workshops. Multidisciplinary teams identified systemic inefficiencies and strategies to improve interdepartmental and patient communication to reduce canceled consultations and cases, diagnostic rework, and no-shows. High-priority triage with enhanced operating room flexibility was instituted to reduce scheduling wait times. General surgery department pilot projects were then implemented mid-FY 2013. Planned outcome measures included wait time, clinic and telehealth volume, number of no-shows, and operative volume. Paired t tests were used to identify differences in outcome measures after the institution of reforms. Following rapid process improvement workshop project rollouts, mean
Scaling of the Time Dependent SGEMP Boundary Layer.
constant in time or rises like any given power of time a single solution suffices for all fluxes. For a more realistic time history with a finite FWHM, the equations reduce to a single parameter family, the parameter being the ratio of the pulse FWHM to the characteristic plasma period. For the time behavior, the unit of time is taken as the FWHM. Both the scaled Boltzmann Equation and Newton’s Equations are
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...
Decoupled Scheme for Time-Dependent Natural Convection Problem II: Time Semidiscreteness
Directory of Open Access Journals (Sweden)
Tong Zhang
2014-01-01
stability and the corresponding optimal error estimates are presented. Furthermore, a decoupled numerical scheme is proposed by decoupling the nonlinear terms via temporal extrapolation; optimal error estimates are established. Finally, some numerical results are provided to verify the performances of the developed algorithms. Compared with the coupled numerical scheme, the decoupled algorithm not only keeps good accuracy but also saves a lot of computational cost. Both theoretical analysis and numerical experiments show the efficiency and effectiveness of the decoupled method for time-dependent natural convection problem.
Delay-dependent stability analysis for discrete-time systems with time varying state delay
Directory of Open Access Journals (Sweden)
Stojanović Sreten B.
2011-01-01
Full Text Available The stability of discrete systems with time-varying delay is considered. Some sufficient delaydependent stability conditions are derived using an appropriate model transformation of the original system. The criteria are presented in the form of LMI, which are dependent on the minimum and maximum delay bounds. It is shown that the stability criteria are approximately the same conservative as the existing ones, but have much simpler mathematical form. The numerical example is presented to illustrate the applicability of the developed results.
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....
Grova, Monica M; Yang, Anthony D; Humphries, Misty D; Galante, Joseph M; Salcedo, Edgardo S
2017-05-19
The surgical community commonly perceives a decline in surgical and patient care skills among residents who take dedicated time away from clinical activity to engage in research. We hypothesize that residents perceive a decline in their skills because of dedicated research time. UC Davis Medical Center, Sacramento, CA, an institutional tertiary care center. General surgery residents and graduates from UC Davis general surgery residency training program, who had completed at least 1 year of research during their training. A total of 35 people were asked to complete the survey, and 19 people submitted a completed survey. Participants were invited to complete an online survey. Factors associated with the decline in skills following their research years were examined. All statistical analyses were performed with IBM SPSS Statistics software. A total of 19 current or former general surgery residents responded to the survey (54% response rate). Overall, 42% described their research as "basic science." Thirteen residents (68%) dedicated 1 year to research, while the remainder spent 2 or more years. Basic science researchers were significantly more likely to report a decrease in clinical judgment (75% vs. 22%, p = 0.013) as well as a decrease in patient care skills (63% vs. 0%, p = 0.002). Residents who dedicated at least 2 years to research were more likely to perceive a decline in overall aptitude and surgical skills (100% vs. 46%, p = 0.02), and a decline in patient care skills (67% vs. 8%, p = 0.007). Most residents who dedicate time for research perceive a decline in their overall clinical aptitude and surgical skills. This can have a dramatic effect on the confidence of these residents in caring for patients and leading a care team once they re-enter clinical training. Residents who engaged in 2 or more years of research were significantly more likely to perceive these problems. Further research should determine how to keep residents who are interested in academics
Scale-dependent intrinsic entropies of complex time series.
Yeh, Jia-Rong; Peng, Chung-Kang; Huang, Norden E
2016-04-13
Multi-scale entropy (MSE) was developed as a measure of complexity for complex time series, and it has been applied widely in recent years. The MSE algorithm is based on the assumption that biological systems possess the ability to adapt and function in an ever-changing environment, and these systems need to operate across multiple temporal and spatial scales, such that their complexity is also multi-scale and hierarchical. Here, we present a systematic approach to apply the empirical mode decomposition algorithm, which can detrend time series on various time scales, prior to analysing a signal's complexity by measuring the irregularity of its dynamics on multiple time scales. Simulated time series of fractal Gaussian noise and human heartbeat time series were used to study the performance of this new approach. We show that our method can successfully quantify the fractal properties of the simulated time series and can accurately distinguish modulations in human heartbeat time series in health and disease.
Wang, Junchen; Suenaga, Hideyuki; Liao, Hongen; Hoshi, Kazuto; Yang, Liangjing; Kobayashi, Etsuko; Sakuma, Ichiro
2015-03-01
Autostereoscopic 3D image overlay for augmented reality (AR) based surgical navigation has been studied and reported many times. For the purpose of surgical overlay, the 3D image is expected to have the same geometric shape as the original organ, and can be transformed to a specified location for image overlay. However, how to generate a 3D image with high geometric fidelity and quantitative evaluation of 3D image's geometric accuracy have not been addressed. This paper proposes a graphics processing unit (GPU) based computer-generated integral imaging pipeline for real-time autostereoscopic 3D display, and an automatic closed-loop 3D image calibration paradigm for displaying undistorted 3D images. Based on the proposed methods, a novel AR device for 3D image surgical overlay is presented, which mainly consists of a 3D display, an AR window, a stereo camera for 3D measurement, and a workstation for information processing. The evaluation on the 3D image rendering performance with 2560×1600 elemental image resolution shows the rendering speeds of 50-60 frames per second (fps) for surface models, and 5-8 fps for large medical volumes. The evaluation of the undistorted 3D image after the calibration yields sub-millimeter geometric accuracy. A phantom experiment simulating oral and maxillofacial surgery was also performed to evaluate the proposed AR overlay device in terms of the image registration accuracy, 3D image overlay accuracy, and the visual effects of the overlay. The experimental results show satisfactory image registration and image overlay accuracy, and confirm the system usability.
[Optimizing surgical hand disinfection].
Kampf, G; Kramer, A; Rotter, M; Widmer, A
2006-08-01
For more than 110 years hands of surgeons have been treated before a surgical procedure in order to reduce the bacterial density. The kind and duration of treatment, however, has changed significantly over time. Recent scientific evidence suggests a few changes with the aim to optimize both the efficacy and the dermal tolerance. Aim of this article is the presentation and discussion of new insights in surgical hand disinfection. A hand wash should be performed before the first disinfection of a day, ideally at least 10 min before the beginning of the disinfection as it has been shown that a 1 min hand wash significantly increases skin hydration for up to 10 min. The application time may be as short as 1.5 min depending on the type of hand rub. Hands and forearms should be kept wet with the hand rub for the recommended application time in any case. A specific rub-in procedure according to EN 12791 has been found to be suitable in order to avoid untreated skin areas. The alcohol-based hand rub should have a proven excellent dermal tolerance in order to ensure appropriate compliance. Considering these elements in clinical practice can have a significant impact to optimize the high quality of surgical hand disinfection for prevention of surgical site infections.
Directory of Open Access Journals (Sweden)
Mokaedi V. Lekgari
2014-01-01
Full Text Available We investigate random-time state-dependent Foster-Lyapunov analysis on subgeometric rate ergodicity of continuous-time Markov chains (CTMCs. We are mainly concerned with making use of the available results on deterministic state-dependent drift conditions for CTMCs and on random-time state-dependent drift conditions for discrete-time Markov chains and transferring them to CTMCs.
Xue, Yuting; Mishra, Brijes; Gao, Danqing
2017-09-01
Field observations have demonstrated that roof failure occurs spatially in a mine from the time of excavation. It is suspected that time-dependent deformation propagates failure in the rock mass. In this paper, the relaxation test is used to study variation in the time-dependent property of rock and the consequent effect on time-dependent roof failure. This investigation uses a numerical simulation in 3DEC. The relaxation equation is developed from Burgers model. Variations in the time-dependent property in the post-failure region show negligible variation and, therefore, are averaged to represent the time-dependent property of the failed rock. Finally, these parameters are used in the numerical simulation of underground excavations. Two groups of parameters are used to represent the time-dependent property for pre- and post-failure conditions. FISH functions within 3DEC are used to monitor the state of each zone. Once failure is detected, the parameters are changed to the values corresponding to failed rock. The results show that the new relaxation model accurately predicts the time-dependent propagation of the failure zone. The variation of the time-dependent parameters significantly affects the rock mass behavior and roof convergence.
Time Variation in Asset Return Dependence: Strength or Structure?
T.D. Markwat (Thijs); H.J.W.G. Kole (Erik); D.J.C. van Dijk (Dick)
2009-01-01
textabstractThe dependence between asset returns varies. Its strength can become stronger or weaker. Also, its structure can change, for example, when asymmetries related to bull and bear markets become more or less pronounced. To analyze these different types of variations, we develop a model that
Surgical ethics and the challenge of surgical innovation.
Angelos, Peter
2014-12-01
Surgical ethics as a specific discipline is relatively new to many. Surgical ethics focuses on the ethical issues that are particularly important to the care of surgical patients. Informed consent for surgical procedures, the level of responsibility that surgeons feel for their patients' outcomes, and the management of surgical innovation are specific issues that are important in surgical ethics and are different from other areas of medicine. The future of surgical progress is dependent on surgical innovation, yet the nature of surgical innovation raises specific concerns that challenge the professionalism of surgeons. These concerns will be considered in the following pages.
Particle Emission-dependent Timing Noise of Pulsars?
Liu, Xiongwei; Xu, Renxin; Qiao, Guojun
2010-01-01
Though pulsars spin regularly, the differences between the observed and predicted ToA (time of arrival), known as "timing noise", can still reach a few milliseconds or more. We try to understand the noise in this paper. As proposed by Xu & Qiao in 2001, both dipole radiation and particle emission would result in pulsar braking. Accordingly, possible fluctuation of particle current flow is suggested here to contribute significant ToA variation of pulsars. We find that the particle emission fluctuation could lead to timing noise which can't be eliminated in timing process, and that a longer period fluctuation would arouse a stronger noise. The simulated timing noise profile and amplitude are in accord with the observed timing behaviors on the timescale of years.
Preconditioning the pressure operator for the time dependent Stokes problem
Energy Technology Data Exchange (ETDEWEB)
Bramble, J.H.; Pasciak, J.E.
1994-12-31
In implicit time stepping procedures for the linearized Navier Stokes equations, a linear perturbed Stokes problem must be solved at each time step. Many methods for doing this require a good preconditioner for the resulting pressure operator (Schur complement). In contrast to the time independent Stokes equations where the pressure operator is well conditioned, the pressure operator for the perturbed system becomes more illconditioned as the time step is reduced (and/or the Reynolds number is increased). The authors describe the method for solving the coupled velocity/pressure systems and, in particular, show how to construct good preconditioners for the poorly conditioned pressure operator.
K shortest paths in stochastic time-dependent networks
DEFF Research Database (Denmark)
Nielsen, Lars Relund; Pretolani, Daniele; Andersen, Kim Allan
2004-01-01
, finding the a priori shortest path is NP-hard, while the best time-adaptive strategy can be found in polynomial time. In this paper, we propose a solution method for the a priori shortest path problem, and we show that it can be easily adapted to the ranking of the first K shortest paths. Moreover, we...
Energy Dependence of SEP Electron and Proton Onset Times
Xie, Hong; Gopalswamy, Nat; Cyr, Orville St
2016-01-01
We study the large solar energetic particle (SEP) events that were detected by GOES in the $>$ 10 MeV energy channel during December 2006 to March 2014. We derive and compare solar particle release (SPR) times for the 0.25--10.4 MeV electrons and 10--100 MeV protons for the 28 SEP events. In the study, the electron SPR times are derived with the time-shifting analysis (TSA) and the proton SPR times are derived using both the TSA and the velocity dispersion analysis (VDA). Electron anisotropies are computed to evaluate the amount of scattering for the events under study. Our main results include: 1)near-relativistic electrons and high-energy protons are released at the same time within 8 min for most (16 of 23) SEP events. 2)There exists a good correlation between electron and proton acceleration, peak intensity and intensity time profiles. 3) The TSA SPR times for 90.5 MeV and 57.4 MeV protons have maximum errors of 6 min and 10 min compared to the proton VDA release times, respectively, while the maximum err...
Ranking paths in stochastic time-dependent networks
DEFF Research Database (Denmark)
Nielsen, Lars Relund; Andersen, Kim Allan; Pretolani, Daniele D.
2014-01-01
be easily extended to the ranking of the first K shortest paths. Our method exploits the solution of the time-adaptive routing problem as a relaxation of the a priori problem. Computational results are presented showing that, under realistic distributions of travel times and costs, our solution methods...
Temperature dependence of fluctuation time scales in spin glasses
DEFF Research Database (Denmark)
Kenning, Gregory G.; Bowen, J.; Sibani, Paolo;
2010-01-01
Using a series of fast cooling protocols we have probed aging effects in the spin glass state as a function of temperature. Analyzing the logarithmic decay found at very long time scales within a simple phenomenological barrier model, leads to the extraction of the fluctuation time scale of the s...
Propagator for a Time-Dependent Damped Harmonic Oscillator with a Force Quadratic in Velocity
Institute of Scientific and Technical Information of China (English)
HUANG Bo-Wen; GU Zhi-Yu; QIAN Shang-Wu
2003-01-01
The propagator for a time-dependent damped harmonic oscillator with a force quadratic in velocity isobtained by making a specific coordinate transformation and by using the method of time-dependent invariant.
Liao, Sheng-Lun; Ho, Tak-San; Rabitz, Herschel; Chu, Shih-I.
2017-06-01
A long-standing challenge in the time-dependent density functional theory is to efficiently solve the exact time-dependent optimized effective potential (TDOEP) integral equation derived from orbital-dependent functionals, especially for the study of nonadiabatic dynamics in time-dependent external fields. In this Letter, we formulate a completely equivalent time-local TDOEP equation that admits a unique real-time solution in terms of time-dependent Kohn-Sham and effective memory orbitals. The time-local formulation is numerically implemented, with the incorporation of exponential memory loss to address the unaccounted for correlation component in the exact-exchange-only functional, to enable the study of the many-electron dynamics of a one-dimensional hydrogen chain. It is shown that the long time behavior of the electric dipole converges correctly and the zero-force theorem is fulfilled in the current implementation.
Two-parameter Failure Model Improves Time-independent and Time-dependent Failure Predictions
Energy Technology Data Exchange (ETDEWEB)
Huddleston, R L
2004-01-27
A new analytical model for predicting failure under a generalized, triaxial stress state was developed by the author and initially reported in 1984. The model was validated for predicting failure under elevated-temperature creep-rupture conditions. Biaxial data for three alloy steels, Types 304 and 316 stainless steels and Inconel 600, demonstrated two to three orders of magnitude reduction in the scatter of predicted versus observed creep-rupture times as compared to the classical failure models of Mises, Tresca, and Rankine. In 1990, the new model was incorporated into American Society of Mechanical Engineers (ASME) Code Case N47-29 for design of components operating under creep-rupture conditions. The current report provides additional validation of the model for predicting failure under time-independent conditions and also outlines a methodology for predicting failure under cyclic, time-dependent, creep-fatigue conditions. The later extension of the methodology may have the potential to improve failure predictions there as well. These results are relevant to most design applications, but they have special relevance to high-performance design applications such as components for high-pressure equipment, nuclear reactors, and jet engines.
Controllable deterioration rate for time-dependent demand and time-varying holding cost
Directory of Open Access Journals (Sweden)
Mishra Vinod Kumar
2014-01-01
Full Text Available In this paper, we develop an inventory model for non-instantaneous deteriorating items under the consideration of the facts: deterioration rate can be controlled by using the preservation technology (PT during deteriorating period, and holding cost and demand rate both are linear function of time, which was treated as constant in most of the deteriorating inventory models. So in this paper, we developed a deterministic inventory model for non-instantaneous deteriorating items in which both demand rate and holding cost are a linear function of time, deterioration rate is constant, backlogging rate is variable and depend on the length of the next replenishment, shortages are allowed and partially backlogged. The model is solved analytically by minimizing the total cost of the inventory system. The model can be applied to optimizing the total inventory cost of non-instantaneous deteriorating items inventory for the business enterprises, where the preservation technology is used to control the deterioration rate, and demand & holding cost both are a linear function of time.
Two-parameter Failure Model Improves Time-independent and Time-dependent Failure Predictions
Energy Technology Data Exchange (ETDEWEB)
Huddleston, R L
2004-01-27
A new analytical model for predicting failure under a generalized, triaxial stress state was developed by the author and initially reported in 1984. The model was validated for predicting failure under elevated-temperature creep-rupture conditions. Biaxial data for three alloy steels, Types 304 and 316 stainless steels and Inconel 600, demonstrated two to three orders of magnitude reduction in the scatter of predicted versus observed creep-rupture times as compared to the classical failure models of Mises, Tresca, and Rankine. In 1990, the new model was incorporated into American Society of Mechanical Engineers (ASME) Code Case N47-29 for design of components operating under creep-rupture conditions. The current report provides additional validation of the model for predicting failure under time-independent conditions and also outlines a methodology for predicting failure under cyclic, time-dependent, creep-fatigue conditions. The later extension of the methodology may have the potential to improve failure predictions there as well. These results are relevant to most design applications, but they have special relevance to high-performance design applications such as components for high-pressure equipment, nuclear reactors, and jet engines.
A trapped ion with time-dependent frequency interaction with a laser field
Energy Technology Data Exchange (ETDEWEB)
MartInez, J M Vargas; Moya-Cessa, H [INAOE, Apartado Postal 51 y 216, 72000 Puebla (Mexico)
2004-06-01
We analyse the problem of a trapped ion with time-dependent frequency interacting with a laser field. By using a set of unitary time-dependent transformations we show that this system is equivalent to the interaction between a quantized field and a double level with time-dependent interaction parameters. In passing, we show that in the on-resonance case different vibrational transitions may be achieved by using time-dependent parameters.
Handling Time-dependent Variables : Antibiotics and Antibiotic Resistance
Munoz-Price, L. Silvia; Frencken, Jos F.; Tarima, Sergey; Bonten, Marc
2016-01-01
Elucidating quantitative associations between antibiotic exposure and antibiotic resistance development is important. In the absence of randomized trials, observational studies are the next best alternative to derive such estimates. Yet, as antibiotics are prescribed for varying time periods, antibi
Handling Time-dependent Variables : Antibiotics and Antibiotic Resistance
Munoz-Price, L. Silvia; Frencken, Jos F.; Tarima, Sergey; Bonten, Marc|info:eu-repo/dai/nl/123144337
2016-01-01
Elucidating quantitative associations between antibiotic exposure and antibiotic resistance development is important. In the absence of randomized trials, observational studies are the next best alternative to derive such estimates. Yet, as antibiotics are prescribed for varying time periods,
Attainable conditions and exact invariant for the time-dependent harmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Guasti, Manuel Fernandez [Lab. de Optica Cuantica, Dep. de Fisica, Universidad A. Metropolitana, Unidad Iztapalapa, Mexico DF, Ap. Post. 55-534 (Mexico)
2006-09-22
The time-dependent oscillator equation is solved numerically for various trajectories in amplitude and phase variables. The solutions exhibit a finite time-dependent parameter whenever the squared amplitude times the derivative of the phase is invariant. If the invariant relationship does not hold, the time-dependent parameter has divergent singularities. These observations lead to the proposition that the harmonic oscillator equation with finite time-dependent parameter must have amplitude and phase solutions fulfilling the invariant relationship. Since the time-dependent parameter or the potential must be finite for any real oscillator implementation, the invariant must hold for any such physically realizable system.
Time-dependent scaling patterns in high frequency financial data
Nava, Noemi; Di Matteo, Tiziana; Aste, Tomaso
2016-10-01
We measure the influence of different time-scales on the intraday dynamics of financial markets. This is obtained by decomposing financial time series into simple oscillations associated with distinct time-scales. We propose two new time-varying measures of complexity: 1) an amplitude scaling exponent and 2) an entropy-like measure. We apply these measures to intraday, 30-second sampled prices of various stock market indices. Our results reveal intraday trends where different time-horizons contribute with variable relative amplitudes over the course of the trading day. Our findings indicate that the time series we analysed have a non-stationary multifractal nature with predominantly persistent behaviour at the middle of the trading session and anti-persistent behaviour at the opening and at the closing of the session. We demonstrate that these patterns are statistically significant, robust, reproducible and characteristic of each stock market. We argue that any modelling, analytics or trading strategy must take into account these non-stationary intraday scaling patterns.
Transmitting time-dependent multimedia data in FDDI networks
Lim, Cheng-Chew; Yao, L.; Zhao, Wei
1993-01-01
Timely delivery of multimedia data is one of the key requirements in a distributed multimedia system. In a token ring network, this can be achieved by a proper control of channel access. FDDI uses a timed token MAC protocol to control the token rotation time. During network initialization, a protocol parameter called target token rotation time (TTRT) is determined. Its value indicates the expected token rotation time. Each node is assigned a fraction of the TTRT, known as synchronous bandwidth, for transmitting its synchronous messages which may be deadline constrained. In this paper, we study methods used for setting the protocol parameters such as TTRT and synchronous bandwidth. The goal is to satisfy the message deadlines. In particular, we discuss the use of the normalized proportional scheme for allocating the synchronous bandwidth. We derive a condition on the utilization factor for ensuring timely delivery of all synchronous messages, and show that 33% utilization is the tight lower bound, regardless of the number of nodes, message lengths, periods, etc. Based on this scheme, we address proper selection of TTRT and trade-off between buffer size and the capability of meeting message deadlines.
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.
Non-Hermitian Swanson model with a time-dependent metric
Fring, Andreas; Moussa, Miled H. Y.
2016-10-01
We provide further nontrivial solutions to the recently proposed time-dependent Dyson and quasi-Hermiticity relation. Here, we solve them for the generalized version of the non-Hermitian Swanson Hamiltonian with time-dependent coefficients. We construct time-dependent solutions by employing the Lewis-Riesenfeld method of invariants and discuss concrete physical applications of our results.
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.
Translation invariant time-dependent massive gravity: Hamiltonian analysis
Energy Technology Data Exchange (ETDEWEB)
Mourad, Jihad; Steer, Danièle A. [Laboratoire APC -- Astroparticule et Cosmologie, Université Paris Diderot, 75013 Paris (France); Noui, Karim, E-mail: mourad@apc.univ-paris7.fr, E-mail: karim.noui@lmpt.univ-tours.fr, E-mail: steer@apc.univ-paris7.fr [Laboratoire de Mathématiques et Physique Théorique, Université François Rabelais, Parc de Grandmont, 37200 Tours (France)
2014-09-01
The canonical structure of the massive gravity in the first order moving frame formalism is studied. We work in the simplified context of translation invariant fields, with mass terms given by general non-derivative interactions, invariant under the diagonal Lorentz group, depending on the moving frame as well as a fixed reference frame. We prove that the only mass terms which give 5 propagating degrees of freedom are the dRGT mass terms, namely those which are linear in the lapse. We also complete the Hamiltonian analysis with the dynamical evolution of the system.
Translation invariant time-dependent massive gravity: Hamiltonian analysis
Mourad, Jihad; Steer, Danièle A
2014-01-01
The canonical structure of the massive gravity in the first order moving frame formalism is studied. We work in the simplified context of translation invariant fields, with mass terms given by general non-derivative interactions, invariant under the diagonal Lorentz group, depending on the moving frame as well as a fixed reference frame. We prove that the only mass terms which give 5 propagating degrees of freedom are the dRGT mass terms, namely those which are linear in the lapse. We also complete the Hamiltonian analysis with the dynamical evolution of the system.
Suction curettage; Surgical abortion; Elective abortion - surgical; Therapeutic abortion - surgical ... Surgical abortion involves dilating the opening to the uterus (cervix) and placing a small suction tube into the uterus. ...
Dark energy models with time-dependent gravitational constant
Ray, S; Ray, Saibal; Mukhopadhyay, Utpal
2005-01-01
Two phenomenological models of $\\Lambda$, viz. $\\Lambda \\sim (\\dot a/a)^2$ and $\\Lambda \\sim \\ddot a/a$ are studied under the assumption that $G$ is a time-variable parameter. Both models show that $G$ is inversely proportional to time as suggested earlier by others including Dirac. The models considered here can be matched with observational results by properly tuning the parameters of the models. Our analysis shows that $\\Lambda \\sim \\ddot a/a$ model corresponds to a repulsive situation and hence correlates with the present status of the accelerating Universe. The other model $\\Lambda \\sim (\\dot a/a)^2$ is, in general, attractive in nature. Moreover, it is seen that due to the combined effect of time-variable $\\Lambda$ and $G$ the Universe evolved with acceleration as well as deceleration. This later one indicates a Big Crunch.
Dark Energy Models with a Time-Dependent Gravitational Constant
Ray, Saibal; Mukhopadhyay, Utpal; Choudhury, S. B. Dutta
Two phenomenological models of Λ, viz. Λ ˜ (˙ a/a)2 and Λ ˜ ḋ a/a, are studied under the assumption that G is a time-variable parameter. Both models show that G is inversely proportional to time, as suggested earlier by others, including Dirac. The models considered here can be matched with observational results by properly tuning the parameters of the models. Our analysis shows that the Λ ˜ ḋ a/a model corresponds to a repulsive situation and hence correlates with the present status of the accelerating Universe. The other model, Λ ˜ (˙ a/a)2, is in general attractive in nature. Moreover, it is seen that due to the combined effect of time-variable Λ and G the Universe evolved with acceleration as well as deceleration. Deceleration indicates a "big crunch".
Time-Dependent Sediment Transport Subjected to Downward Seepage
Institute of Scientific and Technical Information of China (English)
刘小谢; 赵以明; 白玉川
2014-01-01
Experiments were conducted using cohesionless sand particles with median diameter of 0.48 mm to inves-tigate the time variation of sediment transport rate under the influence of local downward seepage. The experimental results show that the bedload transport rate in terms of volumetric sediment transport rate per unit width increased rapidly with time in the presence of suction, eventually reaching a peak beyond which it started to decrease. The trend of reduction was significantly reduced beyond 8 400 s after the test started. The analytical expression was derived in terms of dimensionless sediment transport rate and dimensionless time. The hypothesized relationships were compared with the experimental data, indicating a good agreement with each other.
Time-Dependent Changes in a Shampoo Bubble
Chattopadhyay, Arun
2000-10-01
This article demonstrates the fascinating phenomenon of time evolution of a shampoo bubble through experiments that can be performed by undergraduate students. The changes in thickness of the bubble films with time are followed by UV-vis spectroscopy. The change in chemical composition as a bubble film evolves is monitored by FTIR spectroscopy. It is observed that the change in thickness of a typical shampoo bubble film enclosed in a container is gradual and slow, and the hydrocarbon components of the bubble drain from the bubble much more slowly than water. An additional agent, such as acetonitrile, strikingly alters the dynamics of evolution of such a bubble.
Mathematical model of SPOC with a time dependent reactive field
Energy Technology Data Exchange (ETDEWEB)
Ohtaki, Masako [Department of Physics, School of Science and Engineering, Waseda University, Okubo, Shinjuku-ku, Tokyo 169-8555 (Japan)
2006-03-21
In general the muscle is in one of the two state possible states, relaxation or contraction. These contractions result from relative sliding of myosin and actin in the sarcomere, which is the contraction structure unit of skeletal muscle. The switching between two states is depending on the Ca2{sup +} concentrations. However another state has been detected between these two states. In the third state, that is SPontaneous Oscillatory Contraction (SPOC), sarcomere repeats contraction and extension spontaneously. Muscle fibers are composed of hundreds of sarcomeres in series and one sarcomea also is composed of hundreds of myosin. In microscopic, the force generated by actin and myosin interaction occurs stochastically. SPOC, however, is macroscopically observable and there are regular oscillations. To understand SPOC mechanism, we propose a model for SPOC based on chemical reaction including mechanical process.
Mathematical model of SPOC with a time dependent reactive field
Ohtaki, Masako
2006-03-01
In general the muscle is in one of the two state possible states, relaxation or contraction. These contractions result from relative sliding of myosin and actin in the sarcomere, which is the contraction structure unit of skeletal muscle. The switching between two states is depending on the Ca2+ concentrations. However another state has been detected between these two states. In the third state, that is SPontaneous Oscillatory Contraction (SPOC), sarcomere repeats contraction and extension spontaneously. Muscle fibers are composed of hundreds of sarcomeres in series and one sarcomea also is composed of hundreds of myosin. In microscopic, the force generated by actin and myosin interaction occurs stochastically. SPOC, however, is macroscopically observable and there are regular oscillations. To understand SPOC mechanism, we propose a model for SPOC based on chemical reaction including mechanical process.
Real time propagation of the exact two component time-dependent density functional theory
Goings, Joshua J.; Kasper, Joseph M.; Egidi, Franco; Sun, Shichao; Li, Xiaosong
2016-09-01
We report the development of a real time propagation method for solving the time-dependent relativistic exact two-component density functional theory equations (RT-X2C-TDDFT). The method is fundamentally non-perturbative and may be employed to study nonlinear responses for heavy elements which require a relativistic Hamiltonian. We apply the method to several group 12 atoms as well as heavy-element hydrides, comparing with the extensive theoretical and experimental studies on this system, which demonstrates the correctness of our approach. Because the exact two-component Hamiltonian contains spin-orbit operators, the method is able to describe the non-zero transition moment of otherwise spin-forbidden processes in non-relativistic theory. Furthermore, the two-component approach is more cost effective than the full four-component approach, with similar accuracy. The RT-X2C-TDDFT will be useful in future studies of systems containing heavy elements interacting with strong external fields.
Scale and time dependence of serial correlations in word-length time series of written texts
Rodriguez, E.; Aguilar-Cornejo, M.; Femat, R.; Alvarez-Ramirez, J.
2014-11-01
This work considered the quantitative analysis of large written texts. To this end, the text was converted into a time series by taking the sequence of word lengths. The detrended fluctuation analysis (DFA) was used for characterizing long-range serial correlations of the time series. To this end, the DFA was implemented within a rolling window framework for estimating the variations of correlations, quantified in terms of the scaling exponent, strength along the text. Also, a filtering derivative was used to compute the dependence of the scaling exponent relative to the scale. The analysis was applied to three famous English-written literary narrations; namely, Alice in Wonderland (by Lewis Carrol), Dracula (by Bram Stoker) and Sense and Sensibility (by Jane Austen). The results showed that high correlations appear for scales of about 50-200 words, suggesting that at these scales the text contains the stronger coherence. The scaling exponent was not constant along the text, showing important variations with apparent cyclical behavior. An interesting coincidence between the scaling exponent variations and changes in narrative units (e.g., chapters) was found. This suggests that the scaling exponent obtained from the DFA is able to detect changes in narration structure as expressed by the usage of words of different lengths.
Climate impacts of energy technologies depend on emissions timing
Edwards, Morgan R.; Trancik, Jessika E.
2014-05-01
Energy technologies emit greenhouse gases with differing radiative efficiencies and atmospheric lifetimes. Standard practice for evaluating technologies, which uses the global warming potential (GWP) to compare the integrated radiative forcing of emitted gases over a fixed time horizon, does not acknowledge the importance of a changing background climate relative to climate change mitigation targets. Here we demonstrate that the GWP misvalues the impact of CH4-emitting technologies as mid-century approaches, and we propose a new class of metrics to evaluate technologies based on their time of use. The instantaneous climate impact (ICI) compares gases in an expected radiative forcing stabilization year, and the cumulative climate impact (CCI) compares their time-integrated radiative forcing up to a stabilization year. Using these dynamic metrics, we quantify the climate impacts of technologies and show that high-CH4-emitting energy sources become less advantageous over time. The impact of natural gas for transportation, with CH4 leakage, exceeds that of gasoline within 1-2 decades for a commonly cited 3 W m-2 stabilization target. The impact of algae biodiesel overtakes that of corn ethanol within 2-3 decades, where algae co-products are used to produce biogas and corn co-products are used for animal feed. The proposed metrics capture the changing importance of CH4 emissions as a climate threshold is approached, thereby addressing a major shortcoming of the GWP for technology evaluation.
Internal cartel stability with time-dependent detection probabilities
Hinloopen, J.
2006-01-01
To account for the illegal nature of price-fixing agreements, per-period detection probabilities that can vary over time are introduced in a dynamic oligopoly. The resulting ICCs for internal cartel stability indicate that for discount factors up to 10% per-period detection probabilities of 5% are n
Internal cartel stability with time-dependent detection probabilities
Hinloopen, J.
2006-01-01
To account for the illegal nature of price-fixing agreements, per-period detection probabilities that can vary over time are introduced in a dynamic oligopoly. The resulting ICCs for internal cartel stability indicate that for discount factors up to 10% per-period detection probabilities of 5% are
TAIL INDEX ESTIMATION FOR A FILTERED DEPENDENT TIME SERIES
National Research Council Canada - National Science Library
Jonathan B. Hill
2015-01-01
We prove Hill's (1975) tail index estimator is asymptotically normal when the employed data are generated by a stationary parametric time series (xt(θ0) : t ∈ ℤ} and θ0 is an unknown k × 1 vector. We assume xt(θ0...
Time-Dependent Earthquake Forecasts on a Global Scale
Rundle, J. B.; Holliday, J. R.; Turcotte, D. L.; Graves, W. R.
2014-12-01
We develop and implement a new type of global earthquake forecast. Our forecast is a perturbation on a smoothed seismicity (Relative Intensity) spatial forecast combined with a temporal time-averaged ("Poisson") forecast. A variety of statistical and fault-system models have been discussed for use in computing forecast probabilities. An example is the Working Group on California Earthquake Probabilities, which has been using fault-based models to compute conditional probabilities in California since 1988. An example of a forecast is the Epidemic-Type Aftershock Sequence (ETAS), which is based on the Gutenberg-Richter (GR) magnitude-frequency law, the Omori aftershock law, and Poisson statistics. The method discussed in this talk is based on the observation that GR statistics characterize seismicity for all space and time. Small magnitude event counts (quake counts) are used as "markers" for the approach of large events. More specifically, if the GR b-value = 1, then for every 1000 M>3 earthquakes, one expects 1 M>6 earthquake. So if ~1000 M>3 events have occurred in a spatial region since the last M>6 earthquake, another M>6 earthquake should be expected soon. In physics, event count models have been called natural time models, since counts of small events represent a physical or natural time scale characterizing the system dynamics. In a previous research, we used conditional Weibull statistics to convert event counts into a temporal probability for a given fixed region. In the present paper, we move belyond a fixed region, and develop a method to compute these Natural Time Weibull (NTW) forecasts on a global scale, using an internally consistent method, in regions of arbitrary shape and size. We develop and implement these methods on a modern web-service computing platform, which can be found at www.openhazards.com and www.quakesim.org. We also discuss constraints on the User Interface (UI) that follow from practical considerations of site usability.
Frequency-Dependent Time Lags in Three Blazars
Marscher, Alan P.; Jorstad, Svetlana G.; Aller, Margo F.
2004-01-01
The work completed includes the analysis of observations obtained during Cycle 6 of the Rossi X-ray Timing Explorer (RXTE). The project is part of a longer-term, continuing program to study the X-ray emission process in blazars in collaboration with Dr. Ian McHardy (U. of Southampton, UK). The goals of the program are to study the X-ray emission mechanism in blazars and the relation of the X-ray emission to changes in the relativistic jet. The program includes contemporaneous brightness and linear polarization monitoring at radio and optical wavelengths, total and polarized intensity imaging at 43 GHz with a resolution of 0.1 milliarcseconds with the VLBA, and well-sampled X-ray light curves obtained from a series of approved RXTE programs. During RXTE cycle 6, the project was awarded RXTE time to monitor three quasars: PKS 1510-089 two times per week, and 3C 273 and 3C 279 three times per week each. The X-ray data, including those from earlier cycles, were compared with radio measurements obtained 2-3 times per week in the centimeter-wave band with the Michigan radio telescope, monthly imaging observations with the VLBA at 43 GHz, and optical observations obtained at several telescopes around the world. Since it is the long-term X-ray light curve that is of greatest value, this report includes discussion of all the data collected through August 2003 rather than just the Cycle 6 data.
Miller, David J; Nelson, Carl A; Oleynikov, Dmitry
2009-05-01
With a limited number of access ports, minimally invasive surgery (MIS) often requires the complete removal of one tool and reinsertion of another. Modular or multifunctional tools can be used to avoid this step. In this study, soft computing techniques are used to optimally arrange a modular tool's functional tips, allowing surgeons to deliver treatment of improved quality in less time, decreasing overall cost. The investigators watched University Medical Center surgeons perform MIS procedures (e.g., cholecystectomy and Nissen fundoplication) and recorded the procedures to digital video. The video was then used to analyze the types of instruments used, the duration of each use, and the function of each instrument. These data were aggregated with fuzzy logic techniques using four membership functions to quantify the overall usefulness of each tool. This allowed subsequent optimization of the arrangement of functional tips within the modular tool to decrease overall time spent changing instruments during simulated surgical procedures based on the video recordings. Based on a prototype and a virtual model of a multifunction laparoscopic tool designed by the investigators that can interchange six different instrument tips through the tool's shaft, the range of tool change times is approximately 11-13 s. Using this figure, estimated time savings for the procedures analyzed ranged from 2.5 to over 32 min, and on average, total surgery time can be reduced by almost 17% by using the multifunction tool.
Time dependent electromagnetic fields and 4-dimensional Stokes' theorem
Andosca, Ryan
2016-01-01
Stokes' theorem is central to many aspects of physics -- electromagnetism, the Aharonov-Bohm effect, and Wilson loops to name a few. However, the pedagogical examples and research work almost exclusively focus on situations where the fields are time-independent so that one need only deal with purely spatial line integrals ({\\it e.g.} $\\oint {\\bf A} \\cdot d{\\bf x}$) and purely spatial area integrals ({\\it e.g.} $\\int (\
FINAL REPORT: Multigrid for Systems and Time-Dependent PDEs
Energy Technology Data Exchange (ETDEWEB)
Jones, J. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2016-08-02
This report has two sections. The first section is the motivation for looking at differing discretizations on coarse grids for solving a parabolic equation using multigrid in time. The second section contains selected numerical results from the many experiments conducted. The most interesting result is that for explicit fine grid discretizations, the best coarse discretization (i.e. smallest convergence rates) is a weighting between implicit and explicit methods.
Modeling tropical river runoff:A time dependent approach
Institute of Scientific and Technical Information of China (English)
Rashmi Nigam; Sudhir Nigam; Sushil K.Mittal
2014-01-01
Forecasting of rainfall and subsequent river runoff is important for many operational problems and applications related to hydrol-ogy. Modeling river runoff often requires rigorous mathematical analysis of vast historical data to arrive at reasonable conclusions. In this paper we have applied the stochastic method to characterize and predict river runoff of the perennial Kulfo River in south-ern Ethiopia. The time series analysis based auto regressive integrated moving average (ARIMA) approach is applied to mean monthly runoff data with 10 and 20 years spans. The varying length of the input runoff data is shown to influence the forecasting efficiency of the stochastic process. Preprocessing of the runoff time series data indicated that the data do not follow a seasonal pattern. Our forecasts were made using parsimonious non seasonal ARIMA models and the results were compared to actual 10-year and 20-year mean monthly runoff data of the Kulfo River. Our results indicate that river runoff forecasts based upon the 10-year data are more accurate and efficient than the model based on the 20-year time series.
Time dependent seismicity along the western coast of Canada
Directory of Open Access Journals (Sweden)
Evangelos V. Christou
2016-04-01
Full Text Available Decelerating generation of intermediate magnitude earthquakes (preshocks in a narrow region (seismogenic region and accelerating generation of relatively larger such earthquakes in a broader region (critical region has been proposed as an appropriate model for intermediate-term earthquake prediction. We examined the seismic activity which preceded the Mw=7.7 (October 28, 2012 thrust event that occurred off the west coast of Haida Gwaii, Canada (formerly the Queen Charlotte islands, by applying the decelerating-accelerating seismic strain model. We found that this mainshock was preceded by a pronounced accelerating seismic sequence with the time to the mainshock, as well as by an equally easily identifiable decelerating seismic sequence. Both precursory seismic sequences occurred in different space, time and magnitude windows. The behavior of previous mainshocks that occurred close to the 2012 earthquake was also examined by the time and magnitude predictable regional model. An attempt was also made to identify such seismic strain patterns, which may also be related to the generation of strong mainshocks along the western coast of Canada.
Unbelievable but true: Partial thromboplastin time, kaolin 120 s and yet no surgical bleed!
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Shagun Bhatia Shah
2017-01-01
Full Text Available Partial thromboplastin time, kaolin (PTTK is a global test sensitive to low levels of all the coagulation factors, except Factor VII and Factor XIII. Patients with extensive cancer have a propensity to develop a shortened PTTK. Our breast cancer patient had a prolonged PTTK result roughly 4 times the normal values. A detailed description of the preoperative workup including the special investigations is required to ascertain the cause of the prolongation and precautions taken, leading to successful breast cancer surgery and postoperative period in this patient follows. Allowing the surgeon to operate a patient with a PTTK >120 s and simultaneously at risk of thrombosis due to lupus anticoagulant is possible with a calculated risk and thorough preoperative evaluation. Prophylactic fresh frozen plasma and deep venous thrombosis prophylaxis have an important role.
Second Quantized Scalar QED in Homogeneous Time-Dependent Electromagnetic Fields
Kim, Sang Pyo
2014-01-01
We formulate the second quantized scalar quantum electrodynamics in homogeneous, time-dependent electromagnetic fields, in which the Hamiltonian for a charged scalar field is an infinite system of decoupled time-dependent oscillators for electric fields but of coupled time-dependent oscillators for magnetic fields. We then employ the quantum invariant method to find various quantum states for the charged field. For time-dependent electric fields, a pair of quantum invariant operators for each oscillator plays the role of the time-dependent annihilation and creation operators, constructs the exact quantum states, and gives the vacuum persistence amplitude as well as the pair-production rate. We also find the quantum invariants for the coupled oscillators for the charged field in time-dependent magnetic fields and advance a perturbation method when the magnetic fields change adiabatically. Finally the quantum state and pair production is discussed when a time-dependent electric field is present in parallel to t...
Community structure in time-dependent, multiscale, and multiplex networks.
Mucha, Peter J; Richardson, Thomas; Macon, Kevin; Porter, Mason A; Onnela, Jukka-Pekka
2010-05-14
Network science is an interdisciplinary endeavor, with methods and applications drawn from across the natural, social, and information sciences. A prominent problem in network science is the algorithmic detection of tightly connected groups of nodes known as communities. We developed a generalized framework of network quality functions that allowed us to study the community structure of arbitrary multislice networks, which are combinations of individual networks coupled through links that connect each node in one network slice to itself in other slices. This framework allows studies of community structure in a general setting encompassing networks that evolve over time, have multiple types of links (multiplexity), and have multiple scales.
Time-dependent closure relations for relativistic collisionless fluid equations.
Bendib-Kalache, K; Bendib, A; El Hadj, K Mohammed
2010-11-01
Linear fluid equations for relativistic and collisionless plasmas are derived. Closure relations for the fluid equations are analytically computed from the relativistic Vlasov equation in the Fourier space (ω,k), where ω and k are the conjugate variables of time t and space x variables, respectively. The mathematical method used is based on the projection operator techniques and the continued fraction mathematical tools. The generalized heat flux and stress tensor are calculated for arbitrary parameter ω/kc where c is the speed of light, and for arbitrary relativistic parameter z=mc²/T , where m is the particle rest mass and T, the plasma temperature in energy units.
Deterministic homogenization of parabolic monotone operators with time dependent coefficients
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Gabriel Nguetseng
2004-06-01
Full Text Available We study, beyond the classical periodic setting, the homogenization of linear and nonlinear parabolic differential equations associated with monotone operators. The usual periodicity hypothesis is here substituted by an abstract deterministic assumption characterized by a great relaxation of the time behaviour. Our main tool is the recent theory of homogenization structures by the first author, and our homogenization approach falls under the two-scale convergence method. Various concrete examples are worked out with a view to pointing out the wide scope of our approach and bringing the role of homogenization structures to light.
Time dependent optimal switching controls in online selling models
Energy Technology Data Exchange (ETDEWEB)
Bradonjic, Milan [Los Alamos National Laboratory; Cohen, Albert [MICHIGAN STATE UNIV
2010-01-01
We present a method to incorporate dishonesty in online selling via a stochastic optimal control problem. In our framework, the seller wishes to maximize her average wealth level W at a fixed time T of her choosing. The corresponding Hamilton-Jacobi-Bellmann (HJB) equation is analyzed for a basic case. For more general models, the admissible control set is restricted to a jump process that switches between extreme values. We propose a new approach, where the optimal control problem is reduced to a multivariable optimization problem.
Increasing time delay from presentation until surgical referral for hepatobiliary malignancies
Croome, Kristopher P; Chudzinski, Robyn; Hanto, Douglas W
2010-01-01
Background Studies have shown that delayed treatment of several non-hepatobiliary (HB) malignancies is associated with adverse effects on disease progression and survival. Delayed treatment of HB malignancies has not been thoroughly investigated. Methods We performed a retrospective institutional review of patients referred to the Hepatobiliary Surgery Service at Beth Israel Deaconess Medical Center (BIDMC) for hepatobiliary malignancies from 2002 to 2008. Primary outcomes included the time delays (TD) in patient workup. Secondary outcomes were reasons for delay as well as disparities in TD based on demographic factors. Results Multivariate-adjusted linear regression showed a significant trend of increasing time from presentation until referral to a HB surgeon over the 7-year period (P = 0.001). There were no differences in TD by gender, age or education level. Multivariate-adjusted linear regression showed a significant trend of increasing number of imaging tests performed prior to referral [computerized tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET) and ultrasound and endoscopic ultrasound (US/EUS)] (P 30 days compared with those with a TD1 (TD from presentation until referral) <30 days (P = 0.042). Conclusions Delays were associated with an increase in imaging studies and delays adversely affect survival in resected patients. Referring physicians are encouraged to expedite the evaluation and early referral of all patients to an HB surgeon for evaluation and treatment. PMID:20961373
Nonconvex evolution inclusions generated by time-dependent subdifferential operators
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Kate Arseni-Benou
1999-01-01
Full Text Available We consider nonlinear nonconvex evolution inclusions driven by time-varying subdifferentials ∂ϕ(t,x without assuming that ϕ(t,. is of compact type. We show the existence of extremal solutions and then we prove a strong relaxation theorem. Moreover, we show that under a Lipschitz condition on the orientor field, the solution set of the nonconvex problem is path-connected in C(T,H. These results are applied to nonlinear feedback control systems to derive nonlinear infinite dimensional versions of the bang-bang principle. The abstract results are illustrated by two examples of nonlinear parabolic problems and an example of a differential variational inequality.
The Vehicle Routing Problem with Time Windows and Temporal Dependencies
DEFF Research Database (Denmark)
Rasmussen, Matias Sevel; Dohn, Anders Høeg; Larsen, Jesper
assignment and routing problem with synchronization constraints. The problem has been solved by column generation. The synchronized vehicle dispatching problem (SVDP), which is a dynamic vehicle routing problem with synchronization between vehicles. Constraint programming and local search are applied...... to arrive at high-quality feasible solutions. A problem from the Port of Singapore, where technicians are allocated to service jobs has previously been studied. For each job, a certain combination of technicians with individual skills is needed. The technicians must be present at the same time, and hence...... the schedule for each technician must respect a number of synchronization constraints with other schedules. The problem is solved using metaheuristics. Another application with synchronization between visits is in ground handling at airports. Teams drive around at the airport and are assigned tasks...
Characterizing microstructure of living tissues with time-dependent diffusion
Novikov, Dmitry S; Jensen, Jens H; Helpern, Joseph A
2012-01-01
Molecular diffusion measurements are widely used to probe microstructure in materials and living organisms noninvasively. The precise relation of diffusion metrics to microstructure remains a major challenge: In complex samples, it is often unclear which structural features are most relevant and can be quantified. Here we classify the structural complexity in terms of the long time tail exponent in the molecular velocity autocorrelation function. The specific values of the dynamical exponent let us identify the relevant tissue microanatomy affecting water diffusion measured with MRI in muscles and in brain, and the microstructural changes in ischemic stroke. Our framework presents a systematic way to identify the most relevant part of structural complexity using transport measured with a variety of techniques.
Time Dependence of Collision Probabilities During Satellite Conjunctions
Hall, Doyle T.; Hejduk, Matthew D.; Johnson, Lauren C.
2017-01-01
The NASA Conjunction Assessment Risk Analysis (CARA) team has recently implemented updated software to calculate the probability of collision (P (sub c)) for Earth-orbiting satellites. The algorithm can employ complex dynamical models for orbital motion, and account for the effects of non-linear trajectories as well as both position and velocity uncertainties. This “3D P (sub c)” method entails computing a 3-dimensional numerical integral for each estimated probability. Our analysis indicates that the 3D method provides several new insights over the traditional “2D P (sub c)” method, even when approximating the orbital motion using the relatively simple Keplerian two-body dynamical model. First, the formulation provides the means to estimate variations in the time derivative of the collision probability, or the probability rate, R (sub c). For close-proximity satellites, such as those orbiting in formations or clusters, R (sub c) variations can show multiple peaks that repeat or blend with one another, providing insight into the ongoing temporal distribution of risk. For single, isolated conjunctions, R (sub c) analysis provides the means to identify and bound the times of peak collision risk. Additionally, analysis of multiple actual archived conjunctions demonstrates that the commonly used “2D P (sub c)” approximation can occasionally provide inaccurate estimates. These include cases in which the 2D method yields negligibly small probabilities (e.g., P (sub c)) is greater than 10 (sup -10)), but the 3D estimates are sufficiently large to prompt increased monitoring or collision mitigation (e.g., P (sub c) is greater than or equal to 10 (sup -5)). Finally, the archive analysis indicates that a relatively efficient calculation can be used to identify which conjunctions will have negligibly small probabilities. This small-P (sub c) screening test can significantly speed the overall risk analysis computation for large numbers of conjunctions.
1993-2011 Time dependent deformation of Eyjafjallajokull volcano, Iceland
Ali, T.; Feigl, K.; Pedersen, R.; Sigmundsson, F.
2011-12-01
We analyze synthetic aperture radar data acquired by ERS-1, ERS-2, Envisat, TerraSAR-X and ALOS satellites between 1993 and 2011 to characterize the deformation associated with activity at Eyjafjallajokull. The volcano had shown intermittent unrest for 18 years before erupting in 2010. An effusive lava eruption occurred from 20th March to 12th April and was followed by an explosive summit eruption from 14th April to 22nd May, disrupting air traffic. Satellite radar interferometry (InSAR) captured intrusive events in 1994 and 1999 when several decimeters of deformation occurred on the volcanic edifice. By inverting the geodetic data, Pedersen et al. [2004; 2006] inferred that sills between depths of 5-7 km had increased in volume by approximately 10-17 and 21-31 million cubic meters during each of two intrusive events in 1994 and 1999, respectively. In this study, we extend the time series analysis to the pre-eruptive, co-eruptive, and post-eruptive deformation associated with the 2010 eruptions. To describe the pre-eruptive deformation over several months, Sigmundsson et al. [2010] estimate the total volume increase in two sills and a dike to be 49-71 million cubic meters. During the effusive eruption, no significant deformation was observed in the interferograms. During the explosive eruption, deflation was observed, that continued at a low rate after the eruption ceased. To estimate source parameters, we use the General Inversion of Phase Technique [GIPhT; Feigl and Thurber, 2009] that analyzes the gradient of phase without the need for unwrapping. To quantify the misfit between the observed and modeled values of the phase gradient, the objective function calculates the cost as the absolute value of their difference, averaged over all sampled pixels. To minimize the objective function we use a simulated annealing algorithm. For computational efficiency, we approximate the fitting function using Taylor series. Calculation of derivatives requires evaluating the
Directory of Open Access Journals (Sweden)
Raseelo J. Moitsheki
2008-01-01
Full Text Available Lie point symmetry analysis is performed for an unsteady nonlinear heat diffusion problem modeling thermal energy storage in a medium with a temperature-dependent power law thermal conductivity and subjected to a convective heat transfer to the surrounding environment at the boundary through a variable heat transfer coefficient. Large symmetry groups are admitted even for special choices of the constants appearing in the governing equation. We construct one-dimensional optimal systems for the admitted Lie algebras. Following symmetry reductions, we construct invariant solutions.
Time dependent ethnic convergence in colorectal cancer survival in hawaii
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Hundahl Scott A
2003-02-01
Full Text Available Abstract Background Although colorectal cancer death rates have been declining, this trend is not consistent across all ethnic groups. Biological, environmental, behavioral and socioeconomic explanations exist, but the reason for this discrepancy remains inconclusive. We examined the hypothesis that improved cancer screening across all ethnic groups will reduce ethnic differences in colorectal cancer survival. Methods Through the Hawaii Tumor Registry 16,424 patients diagnosed with colorectal cancer were identified during the years 1960–2000. Cox regression analyses were performed for each of three cohorts stratified by ethnicity (Caucasian, Japanese, Hawaiian, Filipino, and Chinese. The models included stage of diagnosis, year of diagnosis, age, and sex as predictors of survival. Results Mortality rates improved significantly for all ethnic groups. Moreover, with the exception of Hawaiians, rates for all ethnic groups converged over time. Persistently lower survival for Hawaiians appeared linked with more cancer treatment. Conclusion Ethnic disparities in colorectal cancer mortality rates appear primarily the result of differential utilization of health care. If modern screening procedures can be provided equally to all ethnic groups, ethnic outcome differences can be virtually eliminated.
Nahoon: Time-dependent gas-phase chemical model
Wakelam, V.
2014-09-01
Nahoon is a gas-phase chemical model that computes the chemical evolution in a 1D temperature and density structure. It uses chemical networks downloaded from the KInetic Database for Astrochemistry (KIDA) but the model can be adapted to any network. The program is written in Fortran 90 and uses the DLSODES (double precision) solver from the ODEPACK package to solve the coupled stiff differential equations. The solver computes the chemical evolution of gas-phase species at a fixed temperature and density and can be used in one dimension (1D) if a grid of temperature, density, and visual extinction is provided. Grains, both neutral and negatively charged, and electrons are considered as chemical species and their concentrations are computed at the same time as those of the other species. Nahoon contains a test to check the temperature range of the validity of the rate coefficients and avoid extrapolations outside this range. A test is also included to check for duplication of chemical reactions, defined over complementary ranges of temperature.
Implosion Robustness, Time-Dependent Flux Asymmetries and Big Data
Peterson, J. L.; Field, J. E.; Spears, B. K.; Brandon, S. T.; Gaffney, J. A.; Hammer, J.; Kritcher, A.; Nora, R. C.; Springer, P. T.
2015-11-01
Both direct and indirect drive inertial confinement fusion rely on the formation of spherical implosions, which can be a challenge under temporal and spatial drive variations (either from discrete laser beams, a complex hohlraum radiation environment, or both). To that end, we examine the use of large simulation databases of 2D capsule implosions to determine the sensitivity of indirectly driven NIF designs to time-varying low-mode radiation drive asymmetries at varying convergence ratios. In particular, we define and calculate a large number of extensive quantities for the simulations within the database and compare with the equivalent quantities extracted from fully 3D simulations and those used in 1D hydrodynamic models. Additionally, we discuss some of the practical challenges of searching for physical insight in multi-petabyte datasets. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, Lawrence Livermore National Security, LLC. LLNL-ABS-674884.
Time-dependent H2 formation and protonation
Liszt, H S
2009-01-01
Methods: The microscopic equations of H2-formation and protonation are integrated numerically over time in such a manner that the overall structures evolve self-consistently under benign conditions. Results: The equilibrium H2 formation timescale in an H I cloud with N(H) ~ 4x10^{20}/cm^2 is 1-3 x 10^7 yr, nearly independent of the assumed density or H2 formation rate constant on grains, etc. Attempts to speed up the evolution of the H2-fraction would require densities well beyond the range usually considered typical of diffuse gas. The calculations suggest that, under benign, quiescent conditions, formation of H2 is favored in larger regions having moderate density, consistent with the rather high mean kinetic temperatures measured in H2, 70-80 K. Formation of H3+ is essentially complete when H2-formation equilibrates but the final abundance of H3+ appears more nearly at the very last instant. Chemistry in a weakly-molecular gas has particular properties so that the abundance patterns change appreciably as g...
Effect of timing of surgical SSP tendon repair on muscle alterations.
Uhthoff, Hans K; Coletta, Elizabeth; Trudel, Guy
2014-11-01
To investigate the impacts of delayed repairs of a supraspinatus tendon tear on the supraspinatus muscle, we used an animal model data from two previously published studies in which one supraspinatus (SSP) tendon was detached. In one cohort, the rabbits were killed in groups of 10 at 4, 8, and 12 weeks. In the other cohort, a repair was done at these time points, 12 rabbits each, and the animals killed were 12 weeks later. SSP fossa volume (Muscle belly plus extramuscular fat [e-fat] volume), percentage of intramuscular fat (i-fat), and muscle tissue volume (muscle belly volume minus i-fat), as well as CT determination of e-fat and i-fat of both cohorts, were compared. Fossa volume increased (p Muscle belly and muscle tissue volumes did not increase after repair (p > 0.05), but early repair prevented further volume losses, a fact not seen after 8 and 12 weeks delay of repair. No reversal of e-fat or of i-fat occurred, in fact i-fat almost doubled after 4 weeks delay of repair (p fat results. We conclude that early repair prevented loss of muscle belly and muscle tissue volumes, but that it has no positive influence on fat accumulation. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.
The reality of the surgical fasting time in the era of the ERAS protocol
Directory of Open Access Journals (Sweden)
Talita Cestonaro
2014-02-01
Full Text Available Multimodal protocols to optimize perioperative care and to accelerate postoperative recovery include abbreviated pre-and postoperative fasting. The aim of this study was to investigate the pre and postoperative fasting period and the factors that influence it in patients who underwent elective operations. We included patients who underwent surgery of the digestive tract and abdominal wall. Data were collected from the patients and from their personal health records. We included 135 patients between 19 and 89 years old. Most were adults (75.55%, female (60.74% and the most common procedures were hernioplasty (42.96% and cholecystectomy (34.81%. The preoperative fasting periods for solids and liquids were similar, median 16.50 (5.50-56.92 and 15.75 (2.50- 56.92 hours, respectively. The preoperative fasting period was influenced by the instruction received and surgery time. Postoperative fasting period was 15.67 (1.67-90.42 hours and was influenced by type of surgery and lack of synchrony between the clinical meeting and the nutrition and dietetics service schedules.
Karabekir, H Selim; Gocmen-Mas, Nuket; Emel, Erhan; Karacayli, Umit; Koymen, Ramazan; Atar, Elmas Kagnici; Ozkan, Nezih
2012-10-01
The anatomical location of fractures following blunt cranio-orbital trauma is important for neurosurgeons and maxillofacial surgeons. In this study, 588 cranio-orbital fractures following blunt trauma were evaluated retrospectively with regard to the anatomical site and surgical treatment. Orbital cranial nerve injuries and the outcomes of the medical and/or surgical treatment are described. Distribution of the zygomatic complex and orbital fractures were as follows: zygomatic complex fractures (n:304), isolated orbital fractures (n:58), complex comminuted fractures (n:226). In 58 cases, 69 orbit fractures were found (11 bilateral and 47 unilateral fractures). The lateral wall was the most frequent fracture (n:63). The least frequent fracture was the roof of the orbit (n:11). The accompanying lesions were as follows: 89.65% of cases were associated with periorbital haematoma (n:52), 13.79% of cases with retrobulbar haemorrhage (n:8), 96.55% cases with periorbital soft tissue oedema (n:56), 53.45% cases with pneumocephalus (n:31), 8.62% cases with intra-parenchymal contusion (n:5), 6.89% cases with enophthalmia (n:4), 5.17% of cases with rhinorrhoea (n: 3), 5.17% cases with optic bulb injury and adnexial trauma (n:3), 32.76% cases with intra-orbital emphysema (n:19), and 20.69% with vision dysfunctions (n:12), of whom 2 had no optic nerve injury. Copyright © 2011 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Bhargava, Kapilesh, E-mail: kapilesh_66@yahoo.co.u [Architecture and Civil Engineering Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Mori, Yasuhiro [Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8603 (Japan); Ghosh, A.K. [Reactor Safety Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India)
2011-05-15
Research highlights: Predictive models for corrosion-induced damages in RC structures. Formulations for time-dependent flexural and shear strengths of corroded RC beams. Methodology for mean and c.o.v. for time-dependent strengths of corroded RC beams. Simple estimation of mean and c.o.v. for flexural strength with loss of bond. - Abstract: The structural deterioration of reinforced concrete (RC) structures due to reinforcement corrosion is a major worldwide problem. Damages to RC structures due to reinforcement corrosion manifest in the form of expansion, cracking and eventual spalling of the cover concrete; thereby resulting in serviceability and durability degradation of such structures. In addition to loss of cover, RC structure may suffer structural damages due to loss of reinforcement cross-sectional area, and loss of bond between corroded reinforcement and surrounding cracked concrete, sometimes to the extent that the structural failure becomes inevitable. This paper forms the first part of a study which addresses time-dependent reliability analyses of RC beams affected by reinforcement corrosion. In this paper initially the predictive models are presented for the quantitative assessment of time-dependent damages in RC beams, recognized as loss of mass and cross-sectional area of reinforcing bar, loss of concrete section owing to the peeling of cover concrete, and loss of bond between corroded reinforcement and surrounding cracked concrete. Then these models have been used to present analytical formulations for evaluating time-dependent flexural and shear strengths of corroded RC beams, based on the standard composite mechanics expressions for RC sections. Further by considering variability in the identified basic variables that could affect the time-dependent strengths of corrosion-affected RC beams, the estimation of statistical descriptions for the time-dependent strengths is presented for a typical simply supported RC beam. The statistical descriptions
Time-dependent biaxial mechanical behavior of the aortic heart valve leaflet.
Stella, John A; Liao, Jun; Sacks, Michael S
2007-01-01
Despite continued progress in the treatment of aortic valve (AV) disease, current treatments continue to be challenged to consistently restore AV function for extended durations. Improved approaches for AV repair and replacement rests upon our ability to more fully comprehend and simulate AV function. While the elastic behavior the AV leaflet (AVL) has been previously investigated, time-dependent behaviors under physiological biaxial loading states have yet to be quantified. In the current study, we performed strain rate, creep, and stress-relaxation experiments using porcine AVL under planar biaxial stretch and loaded to physiological levels (60 N/m equi-biaxial tension), with strain rates ranging from quasi-static to physiologic. The resulting stress-strain responses were found to be independent of strain rate, as was the observed low level of hysteresis ( approximately 17%). Stress relaxation and creep results indicated that while the AVL exhibited significant stress relaxation, it exhibited negligible creep over the 3h test duration. These results are all in accordance with our previous findings for the mitral valve anterior leaflet (MVAL) [Grashow, J.S., Sacks, M.S., Liao, J., Yoganathan, A.P., 2006a. Planar biaxial creep and stress relaxatin of the mitral valve anterior leaflet. Annals of Biomedical Engineering 34 (10), 1509-1518; Grashow, J.S., Yoganathan, A.P., Sacks, M.S., 2006b. Biaxial stress-stretch behavior of the mitral valve anterior leaflet at physiologic strain rates. Annals of Biomedical Engineering 34 (2), 315-325], and support our observations that valvular tissues are functionally anisotropic, quasi-elastic biological materials. These results appear to be unique to valvular tissues, and indicate an ability to withstand loading without time-dependent effects under physiologic loading conditions. Based on a recent study that suggested valvular collagen fibrils are not intrinsically viscoelastic [Liao, J., Yang, L., Grashow, J., Sacks, M.S., 2007
Effects of Different Time-Dependent Couplings on Two-Atom Entanglement
Institute of Scientific and Technical Information of China (English)
ZHOU Ling; GAO Wen-Bin; YANG Guo-Hui; SONG He-Shan
2007-01-01
The effects of different time-independent and time-dependent couplings on two-atom entanglement are studied. The results show that the effects depend on the initial state. For the initial state |ee0>, it is found that different time-independent couplings make the case without entanglement exhibit entanglement, and time-dependent couplings turn the irregular entanglement regions into regular one. Under the case of decay, for the initial state |eg0>, the different time-dependent couplings have disbenefit.
Analysis of Two-Level Support Systems with Time-Dependent Overflow - A Banking Application
DEFF Research Database (Denmark)
Barth, Wolfgang; Manitz, Michael; Stolletz, Raik
2010-01-01
is available. The analysis of such a system with time-dependent overflow is reduced to the analysis of a continuous-time Markov chain with state-dependent overflow probabilities. To approximate the system with time-dependent overflow, some waiting-based performance measures are modified. Numerical results......In this paper, we analyze the performance of call centers of financial service providers with two levels of support and a time-dependent overflow mechanism. Waiting calls from the front-office queue flow over to the back office if a waiting-time limit is reached and at least one back-office agent...
Time-dependent regulation of yeast glycolysis upon nitrogen starvation depends on cell history
van Eunen, K.; Dool, P.; Canelas, A. B.; Kiewiet, J.; Bouwman, J.; van Gulik, W. M.; Westerhoff, H. V.; Bakker, B. M.
2010-01-01
In this study, the authors investigated how the glycolytic flux was regulated in time upon nitrogen starvation of cells with different growth histories. We have compared cells grown in glucose-limited chemostat cultures under respiratory conditions (low dilution rate of 0.1/h) to cells grown under r
Discontinuous Time Relaxation Method for the Time-Dependent Navier-Stokes Equations
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Monika Neda
2010-01-01
is considered. A fully discrete scheme using discontinuous finite elements is proposed and analyzed. Optimal velocity error estimates are derived. The dependence of these estimates with respect to the Reynolds number Re is (ReRe, which is an improvement with respect to the continuous finite element method where the dependence is (ReRe3.
Krause, Pascal; Schlegel, H Bernhard
2015-06-04
The angle-dependence of strong field ionization of O2, N2, CO2, and CH2O has been studied theoretically using a time-dependent configuration interaction approach with a complex absorbing potential (TDCIS-CAP). Calculation of the ionization yields as a function of the direction of polarization of the laser pulse produces three-dimensional surfaces of the angle-dependent ionization probability. These three-dimensional shapes and their variation with laser intensity can be interpreted in terms of ionization from the highest occupied molecular orbital (HOMO) and lower lying orbitals, and the Dyson orbitals for the ground and excited states of the cations.
Directory of Open Access Journals (Sweden)
Kenneth R. Gundle
2016-04-01
Full Text Available Introduction: Orthopaedic surgery is one of the first seven specialties that began collecting Milestone data as part of the Accreditation Council for Graduate Medical Education's Next Accreditation System (NAS rollout. This transition from process-based advancement to outcome-based education is an opportunity to assess resident and faculty understanding of changing paradigms, and opinions about technical skill evaluation. Methods: In a large academic orthopaedic surgery residency program, residents and faculty were anonymously surveyed. A total of 31/32 (97% residents and 29/53 (55% faculty responded to Likert scale assessments and provided open-ended responses. An internal end-of-rotation audit was conducted to assess timeliness of evaluations. A mixed-method analysis was utilized, with nonparametric statistical testing and a constant-comparative qualitative method. Results: There was greater familiarity with the six core competencies than with Milestones or the NAS (p<0.05. A majority of faculty and residents felt that end-of-rotation evaluations were not adequate for surgical skills feedback. Fifty-eight per cent of residents reported that end-of-rotation evaluations were rarely or never filled out in a timely fashion. An internal audit demonstrated that more than 30% of evaluations were completed over a month after rotation end. Qualitative analysis included themes of resident desire for more face-to-face feedback on technical skills after operative cases, and several barriers to more frequent feedback. Discussion: The NAS and outcome-based education have arrived. Residents and faculty need to be educated on this changing paradigm. This transition period is also a window of opportunity to address methods of evaluation and feedback. In our orthopaedic residency, trainees were significantly less satisfied than faculty with the amount of technical and surgical skills feedback being provided to trainees. The quantitative and qualitative analyses
TIME-DEPENDENT LANDAU SYSTEM AND NON-ADIABATIC BERRY PHASE IN TWO DIMENSIONS
Institute of Scientific and Technical Information of China (English)
Jing Hui; Wu Jian-sheng
2000-01-01
By applying the time-independent unitary transformation, thetime-dependent Landau system is transformed into a product of atime-independent Landau system's Hamiltonian and a factor only dependingon time, which can be solved exactly. Both the invariant operator andthe eigenstate are obtained. In the periodical time-dependent case, thenon-adiabatic Berry's phase is also presented.
Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J; Lopata, Kenneth
2016-09-07
Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.
Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J.; Lopata, Kenneth
2016-09-01
Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.
Numerical modelling of softwood time-dependent behaviour based on microstructure
DEFF Research Database (Denmark)
Engelund, Emil Tang
2010-01-01
by the basic physical mechanism behind the time-dependent behaviour. The mechanism causing time-dependency is thought to be sliding of the microfibrils past each other as a result breaking and re-bonding of hydrogen bonds. This can be incorporated in a numerical model by only allowing time-dependency in shear...... be predicted with the described method of modelling. This is seen by simulating experimental results for both single fibres and tissues in creep and relaxation experiments....
Weak approximation of obliquely reflected diffusions in time-dependent domains
Önskog, Thomas; Nyström, Kaj
2010-01-01
In an earlier paper, we proved the existence of solutions to the Skorohod problem with oblique reflection in time-dependent domains and, subsequently, applied this result to the problem of constructing solutions, in time-dependent domains, to stochastic differential equations with oblique reflection. In this paper we use these results to construct weak approximations of solutions to stochastic differential equations with oblique reflection, in time-dependent domains in R^d, by means of a proj...
Hochstuhl, David
2012-01-01
We introduce the time-dependent restricted active space Configuration Interaction method to solve the time-dependent Schr\\"odinger equation for many-electron atoms, and particularly apply it to the treatment of photoionization processes in atoms. The method is presented in a very general formulation and incorporates a wide range of commonly used approximation schemes, like the single-active electron approximation, time-dependent Configuration Interaction with single-excitations, or the time-dependent R-matrix method. We proof the applicability of the method by calculating the photoionization cross sections of Helium and Beryllium.
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.
... Insert and remove Foley urinary bladder catheter Place pneumatic tourniquet Confirm procedure with surgeon Drape patient within ... Technology and Surgical Assisting (NBSTSA) offers the CertifiedSurgical First Assistant (CSFA) credential, and the National Surgical Assistant ...
Directory of Open Access Journals (Sweden)
Ganesh S
2016-01-01
Full Text Available Sri Ganesh, Sheetal BrarDepartment of Phaco and Refractive Surgeries, Nethradhama Superspeciality Eye Hospital, Bangalore, IndiaPurpose: To compare the effect of two ocular viscosurgical devices (OVDs on intraocular pressure (IOP and surgical time in immediate postoperative period after bilateral implantable collamer lens (using the V4c model implantation.Methods: A total of 20 eligible patients were randomized to receive 2% hydroxypropylmethylcellulose (HPMC in one eye and 1% hyaluronic acid in fellow eye. Time taken for complete removal of OVD and total surgical time were recorded. At the end of surgery, IOP was adjusted between 15 and 20 mmHg in both the eyes.Results: Mean time for complete OVD evacuation and total surgical time were significantly higher in the HPMC group (P=0.00. Four eyes in the HPMC group had IOP spike, requiring treatment. IOP values with noncontact tonometry at 1, 2, 4, 24, and 48 hours were not statistically significant (P>0.05 for both the groups.Conclusion: The study concluded that 1% hyaluronic acid significantly reduces total surgical time, and incidence of acute spikes may be lower compared to 2% HPMC when used for implantable collamer lens (V4c model.Keywords: OVD, hyaluronic acid, ICL, V4c, IOP spikes
Ganesh, Sri; Brar, Sheetal
2016-01-01
Purpose To compare the effect of two ocular viscosurgical devices (OVDs) on intraocular pressure (IOP) and surgical time in immediate postoperative period after bilateral implantable collamer lens (using the V4c model) implantation. Methods A total of 20 eligible patients were randomized to receive 2% hydroxypropylmethylcellulose (HPMC) in one eye and 1% hyaluronic acid in fellow eye. Time taken for complete removal of OVD and total surgical time were recorded. At the end of surgery, IOP was adjusted between 15 and 20 mmHg in both the eyes. Results Mean time for complete OVD evacuation and total surgical time were significantly higher in the HPMC group (P=0.00). Four eyes in the HPMC group had IOP spike, requiring treatment. IOP values with noncontact tonometry at 1, 2, 4, 24, and 48 hours were not statistically significant (P>0.05) for both the groups. Conclusion The study concluded that 1% hyaluronic acid significantly reduces total surgical time, and incidence of acute spikes may be lower compared to 2% HPMC when used for implantable collamer lens (V4c model). PMID:26869754
New Delay-Dependent Stability of Uncertain Discrete-Time Switched Systems with Time-Varying Delays
Institute of Scientific and Technical Information of China (English)
Liang Lin XIONG; Shou Ming ZHONG; Mao YE
2011-01-01
This paper deals with the issues of robust stability for uncertain discrete-time switched systems with mode-dependent time delays. Based on a novel difference inequality and a switched Lyapunov function, new delay-dependent stability criteria are formulated in terms of linear matrix inequalities (LMIs) which are not contained in known literature. A numerical example is given to demonstrate that the proposed criteria improves some existing results significantly with much less computational effort.
Delay-Dependent Exponential Stability for Discrete-Time BAM Neural Networks with Time-Varying Delays
Directory of Open Access Journals (Sweden)
Yonggang Chen
2008-01-01
Full Text Available This paper considers the delay-dependent exponential stability for discrete-time BAM neural networks with time-varying delays. By constructing the new Lyapunov functional, the improved delay-dependent exponential stability criterion is derived in terms of linear matrix inequality (LMI. Moreover, in order to reduce the conservativeness, some slack matrices are introduced in this paper. Two numerical examples are presented to show the effectiveness and less conservativeness of the proposed method.
Directory of Open Access Journals (Sweden)
Behrouz Afshar-Nadjafi
2017-01-01
Full Text Available In this paper, we consider the time-dependent multi-depot vehicle routing problem. The objective is to minimize the total heterogeneous fleet cost assuming that the travel time between locations depends on the departure time. Also, hard time window constraints for the customers and limitation on maximum number of the vehicles in depots must be satisfied. The problem is formulated as a mixed integer programming model. A constructive heuristic procedure is proposed for the problem. Also, the efficiency of the proposed algorithm is evaluated on 180 test problems. The obtained computational results indicate that the procedure is capable to obtain a satisfying solution.
Directory of Open Access Journals (Sweden)
Tägil Magnus
2009-05-01
Full Text Available Abstract Background Rheumatic diseases commonly affect joints and other structures in the hand. Surgery is a traditional way to treat hand problems in inflammatory rheumatic diseases with the purposes of pain relief, restore function and prevent progression. There are numerous measures to choose from, and a combination of outcome measures is recommended. This study evaluated if instruments commonly used in rheumatologic clinical practice are suitable to measure outcome of hand surgery and to identify time points relevant for follow-up. Methods Thirty-one patients (median age 56 years, median disease duration 15 years with inflammatory rheumatic disease and need for post-surgical occupational therapy intervention formed this pilot study group. Hand function was assessed regarding grip strength (Grippit, pain (VAS, range of motion (ROM (Signals of Functional Impairment (SOFI and grip ability (Grip Ability Test (GAT. Activities of daily life (ADL were assessed by means of Disabilities of the Arm, Shoulder and Hand Outcome (DASH and Canadian Occupational Performance Measure (COPM. The instruments were evaluated by responsiveness and feasibility; follow-up points were 0, 3, 6 and 12 months. Results All instruments showed significant change at one or more follow-up points. Satisfaction with activities (COPM showed the best responsiveness (SMR>0.8, while ROM measured with SOFI had low responsiveness at most follow-up time points. The responsiveness of the instruments was stable between 6 and 12 month follow-up which imply that 6 month is an appropriate time for evaluating short-term effect of hand surgery in rheumatic diseases. Conclusion We suggest a core set of instruments measuring pain, grip strength, grip ability, perceived symptoms and self-defined daily activities. This study has shown that VAS pain, the Grippit instrument, GAT, DASH symptom scale and COPM are suitable outcome instruments for hand surgery, while SOFI may be a more insensitive
Investigating Student Difficulties with Time dependence of Expectation Values in Quantum Mechanics
Marshman, Emily
2015-01-01
Quantum mechanics is challenging even for advanced undergraduate and graduate students. In the Schr\\"odinger representation, the wave function evolves in time according to the time dependent Schr\\"odinger equation. The time dependence of the wave function gives rise to time dependence of the expectation value of observables. We have been exploring the difficulties that advanced undergraduate and graduate students have with time dependence of expectation values in quantum mechanics. We have developed and administered conceptual free response and multiple-choice questions to students to investigate these difficulties. We also interviewed 23 students individually using a think-aloud protocol to obtain a better understanding of the rationale behind students' written responses. We find that many students struggle with time dependence of expectation values of observables. We discuss some findings.
Analyzing Density Operator in Thermal State for Complicated Time-Dependent Optical Systems
Directory of Open Access Journals (Sweden)
Jeong Ryeol Choi
2014-01-01
Full Text Available Density operator of oscillatory optical systems with time-dependent parameters is analyzed. In this case, a system is described by a time-dependent Hamiltonian. Invariant operator theory is introduced in order to describe time-varying behavior of the system. Due to the time dependence of parameters, the frequency of oscillation, so-called a modified frequency of the system, is somewhat different from the natural frequency. In general, density operator of a time-dependent optical system is represented in terms of the modified frequency. We showed how to determine density operator of complicated time-dependent optical systems in thermal state. Usually, density operator description of quantum states is more general than the one described in terms of the state vector.
A Directed Continuous Time Random Walk Model with Jump Length Depending on Waiting Time
Directory of Open Access Journals (Sweden)
Long Shi
2014-01-01
Full Text Available In continuum one-dimensional space, a coupled directed continuous time random walk model is proposed, where the random walker jumps toward one direction and the waiting time between jumps affects the subsequent jump. In the proposed model, the Laplace-Laplace transform of the probability density function P(x,t of finding the walker at position x at time t is completely determined by the Laplace transform of the probability density function φ(t of the waiting time. In terms of the probability density function of the waiting time in the Laplace domain, the limit distribution of the random process and the corresponding evolving equations are derived.
Quantum Statistics of a Forced Oscillator with a Time-Dependent Driving Force
Institute of Scientific and Technical Information of China (English)
刘文森
2003-01-01
Quantum statistics of a forced harmonic oscillator acted upon by a time-dependent external force are derived using the Wilcox trick and the time-dependent inhomogeneous Bogoliubov transformation formalism.The internal energy,fluctuation of the particle-number average and entropy of this nonequilibrium system are presented explicitly.
Directory of Open Access Journals (Sweden)
Marcos Moshinsky
2008-07-01
Full Text Available For classical canonical transformations, one can, using the Wigner transformation, pass from their representation in Hilbert space to a kernel in phase space. In this paper it will be discussed how the time-dependence of the uncertainties of the corresponding time-dependent quantum problems can be incorporated into this formalism.
Domínguez, Alvaro
2014-12-01
It has been shown recently that the coefficient of collective diffusion in a colloidal monolayer is divergent due to the hydrodynamic interactions mediated by the ambient fluid in bulk. The analysis is extended to allow for time-dependent hydrodynamic interactions. Observational features specific to this time dependency are predicted. The possible experimental detection in the dynamics of the monolayer is discussed.
Program for quantum wave-packet dynamics with time-dependent potentials
Dion, C M; Rahali, G
2014-01-01
We present a program to simulate the dynamics of a wave packet interacting with a time-dependent potential. The time-dependent Schr\\"odinger equation is solved on a one-, two-, or three-dimensional spatial grid using the split operator method. The program can be compiled for execution either on a single processor or on a distributed-memory parallel computer.
First integrals for time-dependent higher-order Riccati equations by nonholonomic transformation
Guha, Partha; Ghose Choudhury, A.; Khanra, Barun
2011-08-01
We exploit the notion of nonholonomic transformations to deduce a time-dependent first integral for a (generalized) second-order nonautonomous Riccati differential equation. It is further shown that the method can also be used to compute the first integrals of a particular class of third-order time-dependent ordinary differential equations and is therefore quite robust.
Enabling time-dependent uncertain eco-weights for road networks
DEFF Research Database (Denmark)
Hu, Jilin; Yang, Bin; Jensen, Christian Søndergaard;
2017-01-01
dependent and uncertain. We formalize the problem of assigning a time-dependent, uncertain eco-weight to each edge in a road network based on historical GPS records. In particular, a sequence of histograms is employed to describe the uncertain eco-weight of an edge at different time intervals. Compression...
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.
Simulating the time-dependent behaviour of excavations in hard rock
CSIR Research Space (South Africa)
Malan, DF
2002-10-01
Full Text Available associated with using viscoelastic theory to simulate the time-dependent behaviour of hard rock, a viscoelastic convergence solution for the incremental enlargement of a tabular excavation is discussed. Data on the time dependent deformation of a tunnel...
Modelling time-dependent mechanical behaviour of softwood using deformation kinetics
DEFF Research Database (Denmark)
Engelund, Emil Tang; Svensson, Staffan
2010-01-01
The time-dependent mechanical behaviour (TDMB) of softwood is relevant, e.g., when wood is used as building material where the mechanical properties must be predicted for decades ahead. The established mathematical models should be able to predict the time-dependent behaviour. However, these models...
Time-dependent transport in interacting and noninteracting resonant-tunneling systems
DEFF Research Database (Denmark)
Jauho, Antti-Pekka; Wingreen, Ned S.; Meir, Yigal
1994-01-01
We consider a mesoscopic region coupled to two leads under the influence of external time-dependent voltages. The time dependence is coupled to source and drain contacts, the gates controlling the tunnel-barrier heights, or to the gates that define the mesoscopic region. We derive, with the Keldy...
Time-Dependence effect in alumite recording media with perpendicular anisotropy
Phan le kim, P.L.K.; Lodder, J.C.
1999-01-01
In this paper, we will present a study of the time-dependence effect in alumite perpendicular media at different thicknesses. Important parameters of the time-dependence effect such as magnetic viscosity and activation volume are investigated. Viscosity as a function of applied field (viscosity
Modified $f(R)$ Gravity and Thermodynamics of Time-Dependent Wormholes at Event Horizon
Saiedi, H
2016-01-01
In the context of modified $f(R)$ gravity theory, we study time-dependent wormhole spacetimes in the radiation background. In this framework, we attempt to generalize the thermodynamic properties of time-dependent wormholes in $f(R)$ gravity. Finally, at event horizon, the rate of change of total entropy has been discussed.
Time-Dependence effect in alumite recording media with perpendicular anisotropy
Kim, Phan Le; Lodder, Cock
1999-01-01
In this paper, we will present a study of the time-dependence effect in alumite perpendicular media at different thicknesses. Important parameters of the time-dependence effect such as magnetic viscosity and activation volume are investigated. Viscosity as a function of applied field (viscosity cur
Invariant Hermitian Operator and Density Operator for the Adiabatically Time-Dependent System
Institute of Scientific and Technical Information of China (English)
YAN Feng-Li; YANG Lin-Guang
2001-01-01
The density operator is approximately expressed as a function of the invariant Hermitian operator for the adiabatically time-dependent system. Using this method, the calculation of the density operator for the Heisenberg spin system in a weakly time-dependent magnetic field is exemplified. By virtue of the density operator, we obtain equilibrium.``