Laminar burning velocity and ignition delay time for premixed isooctane-air flames with syngas addition

NASA Astrophysics Data System (ADS)

Bhattacharya, Atmadeep; Datta, Amitava; Wensing, Michael

2017-03-01

The effects of blending syngas in different proportions to isooctane on the laminar burning velocity and ignition delay time of the fuel-air mixture have been studied in SI engine relevant conditions. The syngas is assumed to be composed of 50% H2 and 50% CO. Simulations have been carried out using a skeletal mechanism containing 143 species and 643 reaction steps. It has been found that the blending of syngas augments the laminar burning velocity of isooctane due to increase of the thermal diffusivity of the reactant mixture and alteration in the chemistry of the flame reactions. For the mixture of 30% isooctane/70% syngas, the laminar burning velocity and the ignition delay time values are very close to those corresponding to pure isooctane. Additionally, the effects of exhaust gas recirculation have been explored for the 30% isooctane/70% syngas-air flame. It is seen that the reduction in laminar burning velocity due to the dilution by the recirculated exhaust gas can be compensated by an increase in the unburnt gas temperature. The effect of the exhaust gas dilution on the ignition delay time of 30% isooctane/70% syngas-air mixture has been found to be negligible.

Fractional order absolute vibration suppression (AVS) controllers

NASA Astrophysics Data System (ADS)

Halevi, Yoram

2017-04-01

Absolute vibration suppression (AVS) is a control method for flexible structures. The first step is an accurate, infinite dimension, transfer function (TF), from actuation to measurement. This leads to the collocated, rate feedback AVS controller that in some cases completely eliminates the vibration. In case of the 1D wave equation, the TF consists of pure time delays and low order rational terms, and the AVS controller is rational. In all other cases, the TF and consequently the controller are fractional order in both the delays and the "rational parts". The paper considers stability, performance and actual implementation in such cases.

Dynamics of human T-cell lymphotropic virus I (HTLV-I) infection of CD4+ T-cells.

PubMed

Katri, Patricia; Ruan, Shigui

2004-11-01

Stilianakis and Seydel (Bull. Math. Biol., 1999) proposed an ODE model that describes the T-cell dynamics of human T-cell lymphotropic virus I (HTLV-I) infection and the development of adult T-cell leukemia (ATL). Their model consists of four components: uninfected healthy CD4+ T-cells, latently infected CD4+ T-cells, actively infected CD4+ T-cells, and ATL cells. Mathematical analysis that completely determines the global dynamics of this model has been done by Wang et al. (Math. Biosci., 2002). In this note, we first modify the parameters of the model to distinguish between contact and infectivity rates. Then we introduce a discrete time delay to the model to describe the time between emission of contagious particles by active CD4+ T-cells and infection of pure cells. Using the results in Culshaw and Ruan (Math. Biosci., 2000) in the analysis of time delay with respect to cell-free viral spread of HIV, we study the effect of time delay on the stability of the endemically infected equilibrium. Numerical simulations are presented to illustrate the results.

Hybrid Smith predictor and phase lead based divergence compensation for hardware-in-the-loop contact simulation with measurement delay

NASA Astrophysics Data System (ADS)

Qi, Chenkun; Gao, Feng; Zhao, Xianchao; Wang, Qian; Ren, Anye

2018-06-01

On the ground the hardware-in-the-loop (HIL) simulation is a good approach to test the contact dynamics of spacecraft docking process in space. Unfortunately, due to the time delay in the system the HIL contact simulation becomes divergent. However, the traditional first-order phase lead compensation approach still result in a small divergence for the pure time delay. The serial Smith predictor and phase lead compensation approach proposed by the authors recently will lead to an over-compensation and an obvious convergence. In this study, a hybrid Smith predictor and phase lead compensation approach is proposed. The hybrid Smith predictor and phase lead compensation can achieve a higher simulation fidelity with a little convergence. The phase angle of the compensator is analyzed and the stability condition of the HIL simulation system is given. The effectiveness of the proposed compensation approach is tested by simulations on an undamped elastic contact process.

Transition from Target to Gaze Coding in Primate Frontal Eye Field during Memory Delay and Memory-Motor Transformation.

PubMed

Sajad, Amirsaman; Sadeh, Morteza; Yan, Xiaogang; Wang, Hongying; Crawford, John Douglas

2016-01-01

The frontal eye fields (FEFs) participate in both working memory and sensorimotor transformations for saccades, but their role in integrating these functions through time remains unclear. Here, we tracked FEF spatial codes through time using a novel analytic method applied to the classic memory-delay saccade task. Three-dimensional recordings of head-unrestrained gaze shifts were made in two monkeys trained to make gaze shifts toward briefly flashed targets after a variable delay (450-1500 ms). A preliminary analysis of visual and motor response fields in 74 FEF neurons eliminated most potential models for spatial coding at the neuron population level, as in our previous study (Sajad et al., 2015). We then focused on the spatiotemporal transition from an eye-centered target code (T; preferred in the visual response) to an eye-centered intended gaze position code (G; preferred in the movement response) during the memory delay interval. We treated neural population codes as a continuous spatiotemporal variable by dividing the space spanning T and G into intermediate T-G models and dividing the task into discrete steps through time. We found that FEF delay activity, especially in visuomovement cells, progressively transitions from T through intermediate T-G codes that approach, but do not reach, G. This was followed by a final discrete transition from these intermediate T-G delay codes to a "pure" G code in movement cells without delay activity. These results demonstrate that FEF activity undergoes a series of sensory-memory-motor transformations, including a dynamically evolving spatial memory signal and an imperfect memory-to-motor transformation.

Research on key technologies of LADAR echo signal simulator

NASA Astrophysics Data System (ADS)

Xu, Rui; Shi, Rui; Ye, Jiansen; Wang, Xin; Li, Zhuo

2015-10-01

LADAR echo signal simulator is one of the most significant components of hardware-in-the-loop (HWIL) simulation systems for LADAR, which is designed to simulate the LADAR return signal in laboratory conditions. The device can provide the laser echo signal of target and background for imaging LADAR systems to test whether it is of good performance. Some key technologies are investigated in this paper. Firstly, the 3D model of typical target is built, and transformed to the data of the target echo signal based on ranging equation and targets reflection characteristics. Then, system model and time series model of LADAR echo signal simulator are established. Some influential factors which could induce fixed delay error and random delay error on the simulated return signals are analyzed. In the simulation system, the signal propagating delay of circuits and the response time of pulsed lasers are belong to fixed delay error. The counting error of digital delay generator, the jitter of system clock and the desynchronized between trigger signal and clock signal are a part of random delay error. Furthermore, these system insertion delays are analyzed quantitatively, and the noisy data are obtained. The target echo signals are got by superimposing of the noisy data and the pure target echo signal. In order to overcome these disadvantageous factors, a method of adjusting the timing diagram of the simulation system is proposed. Finally, the simulated echo signals are processed by using a detection algorithm to complete the 3D model reconstruction of object. The simulation results reveal that the range resolution can be better than 8 cm.

Modified superposition: A simple time series approach to closed-loop manual controller identification

NASA Technical Reports Server (NTRS)

Biezad, D. J.; Schmidt, D. K.; Leban, F.; Mashiko, S.

1986-01-01

Single-channel pilot manual control output in closed-tracking tasks is modeled in terms of linear discrete transfer functions which are parsimonious and guaranteed stable. The transfer functions are found by applying a modified super-position time series generation technique. A Levinson-Durbin algorithm is used to determine the filter which prewhitens the input and a projective (least squares) fit of pulse response estimates is used to guarantee identified model stability. Results from two case studies are compared to previous findings, where the source of data are relatively short data records, approximately 25 seconds long. Time delay effects and pilot seasonalities are discussed and analyzed. It is concluded that single-channel time series controller modeling is feasible on short records, and that it is important for the analyst to determine a criterion for best time domain fit which allows association of model parameter values, such as pure time delay, with actual physical and physiological constraints. The purpose of the modeling is thus paramount.

Optimal Integration of Departure and Arrivals in Terminal Airspace

NASA Technical Reports Server (NTRS)

Xue, Min; Zelinski, Shannon Jean

2012-01-01

Coordination of operations with spatially and temporally shared resources such as route segments, fixes, and runways improves the efficiency of terminal airspace management. Problems in this category include scheduling and routing, thus they are normally difficult to solve compared with pure scheduling problems. In order to reduce the computational time, a fast time algorithm formulation using a non-dominated sorting genetic algorithm (NSGA) was introduced in this work and applied to a test case based on existing literature. The experiment showed that new method can solve the whole problem in fast time instead of solving sub-problems sequentially with a window technique. The results showed a 60% or 406 second delay reduction was achieved by sharing departure fixes (more details on the comparison with MILP results will be presented in the final paper). Furthermore, the NSGA algorithm was applied to a problem in LAX terminal airspace, where interactions between 28% of LAX arrivals and 10% of LAX departures are resolved by spatial segregation, which may introduce unnecessary delays. In this work, spatial segregation, temporal segregation, and hybrid segregation were formulated using the new algorithm. Results showed that spatial and temporal segregation approaches achieved similar delay. Hybrid segregation introduced much less delay than the other two approaches. For a total of 9 interacting departures and arrivals, delay reduction varied from 4 minutes to 6.4 minutes corresponding flight time uncertainty from 0 to 60 seconds. Considering the amount of flights that could be affected, total annual savings with hybrid segregation would be significant.

Differentiation of Speech Delay and Global Developmental Delay in Children Using DTI Tractography-Based Connectome.

PubMed

Jeong, J-W; Sundaram, S; Behen, M E; Chugani, H T

2016-06-01

Pure speech delay is a common developmental disorder which, according to some estimates, affects 5%-8% of the population. Speech delay may not only be an isolated condition but also can be part of a broader condition such as global developmental delay. The present study investigated whether diffusion tensor imaging tractography-based connectome can differentiate global developmental delay from speech delay in young children. Twelve children with pure speech delay (39.1 ± 20.9 months of age, 9 boys), 14 children with global developmental delay (39.3 ± 18.2 months of age, 12 boys), and 10 children with typical development (38.5 ± 20.5 months of age, 7 boys) underwent 3T DTI. For each subject, whole-brain connectome analysis was performed by using 116 cortical ROIs. The following network metrics were measured at individual regions: strength (number of the shortest paths), efficiency (measures of global and local integration), cluster coefficient (a measure of local aggregation), and betweeness (a measure of centrality). Compared with typical development, global and local efficiency were significantly reduced in both global developmental delay and speech delay (P < .0001). The nodal strength of the cognitive network is reduced in global developmental delay, whereas the nodal strength of the language network is reduced in speech delay. This finding resulted in a high accuracy of >83% ± 4% to discriminate global developmental delay from speech delay. The network abnormalities identified in the present study may underlie the neurocognitive and behavioral consequences commonly identified in children with global developmental delay and speech delay. Further validation studies in larger samples are required. © 2016 by American Journal of Neuroradiology.

Auto-ignitions of a methane/air mixture at high and intermediate temperatures

NASA Astrophysics Data System (ADS)

Leschevich, V. V.; Martynenko, V. V.; Penyazkov, O. G.; Sevrouk, K. L.; Shabunya, S. I.

2016-09-01

A rapid compression machine (RCM) and a shock tube (ST) have been employed to study ignition delay times of homogeneous methane/air mixtures at intermediate-to-high temperatures. Both facilities allow measurements to be made at temperatures of 900-2000 K, at pressures of 0.38-2.23 MPa, and at equivalence ratios of 0.5, 1.0, and 2.0. In ST experiments, nitrogen served as a diluent gas, whereas in RCM runs the diluent gas composition ranged from pure nitrogen to pure argon. Recording pressure, UV, and visible emissions identified the evolution of chemical reactions. Correlations of ignition delay time were generated from the data for each facility. At temperatures below 1300 K, a significant reduction of average activation energy from 53 to 15.3 kcal/mol was obtained. Moreover, the RCM data showed significant scatter that dramatically increased with decreasing temperature. An explanation for the abnormal scatter in the data was proposed based on the high-speed visualization of auto-ignition phenomena and experiments performed with oxygen-free and fuel-free mixtures. It is proposed that the main reason for such a significant reduction of average activation energy is attributable to the premature ignition of ultrafine particles in the reactive mixture.

Biodegradable polymer for sealing porous PEO layer on pure magnesium: An in vitro degradation study

NASA Astrophysics Data System (ADS)

Alabbasi, Alyaa; Mehjabeen, Afrin; Kannan, M. Bobby; Ye, Qingsong; Blawert, Carsten

2014-05-01

An attempt was made to seal the porous silicate-based plasma electrolytic oxidation (PEO) layer on pure magnesium (Mg) with a biodegradable polymer, poly(L-lactide) (PLLA), to delay the localized degradation of magnesium-based implants in body fluid for better in-service mechanical integrity. Firstly, a silicate-based PEO coating on pure magnesium was performed using a pulsed constant current method. In order to seal the pores in the PEO layer, PLLA was coated using a two-step spin coating method. The performance of the PEO-PLLA Mg was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The EIS results showed that the polarization resistance (Rp) of the PEO-PLLA Mg was close to two orders of magnitude higher than that of the PEO Mg. While the corrosion current density (icorr) of the pure Mg was reduced by 65% with the PEO coating, the PEO-PLLA coating reduced the icorr by almost 100%. As expected, the Rp of the PEO-PLLA Mg decreased with increase in exposure time. However, it was noted that the Rp of the PEO-PLLA Mg even after 100 h was six times higher than that of the PEO Mg after 48 h exposure, and did not show any visible localized attack.

Frequency response control of semiconductor laser by using hybrid modulation scheme.

PubMed

Mieda, Shigeru; Yokota, Nobuhide; Isshiki, Ryuto; Kobayashi, Wataru; Yasaka, Hiroshi

2016-10-31

A hybrid modulation scheme that simultaneously applies the direct current modulation and intra-cavity loss modulation to a semiconductor laser is proposed. Both numerical calculations using rate equations and experiments using a fabricated laser show that the hybrid modulation scheme can control the frequency response of the laser by changing a modulation ratio and time delay between the two modulations. The modulation ratio and time delay provide the degree of signal mixing of the two modulations and an optimum condition is found when a non-flat frequency response for the intra-cavity loss modulation is compensated by that for the direct current modulation. We experimentally confirm a 8.64-dB improvement of the modulation sensitivity at 20 GHz compared with the pure direct current modulation with a 0.7-dB relaxation oscillation peak.

Bilevel shared control for teleoperators

NASA Technical Reports Server (NTRS)

Hayati, Samad A. (Inventor); Venkataraman, Subramanian T. (Inventor)

1992-01-01

A shared system is disclosed for robot control including integration of the human and autonomous input modalities for an improved control. Autonomously planned motion trajectories are modified by a teleoperator to track unmodelled target motions, while nominal teleoperator motions are modified through compliance to accommodate geometric errors autonomously in the latter. A hierarchical shared system intelligently shares control over a remote robot between the autonomous and teleoperative portions of an overall control system. Architecture is hierarchical, and consists of two levels. The top level represents the task level, while the bottom, the execution level. In space applications, the performance of pure teleoperation systems depend significantly on the communication time delays between the local and the remote sites. Selection/mixing matrices are provided with entries which reflect how each input's signals modality is weighted. The shared control minimizes the detrimental effects caused by these time delays between earth and space.

Transfusion Support for ABO-Incompatible Progenitor Cell Transplantation

PubMed Central

Kopko, Patricia M.

2016-01-01

Summary ABO-incompatible transplants comprise up to 50% of allogeneic progenitor cell transplants. Major, minor and bidirectional ABO-incompatible transplants each have unique complications that can occur, including hemolysis at the time of progenitor cell infusion, hemolysis during donor engraftment, passenger lymphocyte syndrome, delayed red blood cell engraftment, and pure red cell aplasia. Appropriate transfusion support during the different phases of the allogeneic progenitor cell transplant process is an important part of ABO-incompatible transplantation. PMID:27022318

Global attractivity of non-autonomous Lotka-Volterra competition system without instantaneous negative feedback

NASA Astrophysics Data System (ADS)

Tang, X. H.; Zou, Xingfu

We consider a non-autonomous Lotka-Volterra competition system with distributed delays but without instantaneous negative feedbacks (i.e., pure delay systems). We establish some 3/2-type and M-matrix-type criteria for global attractivity of the positive equilibrium of the system, which generalise and improve the existing ones.

Pure culture response of ectomycorrhizal fungi to imposed water stress

Treesearch

Mark D. Coleman; Caroline S. Bledsoe; William Lopushinsky

1989-01-01

The ability of ectomycorrhizal fungal isolates to tolerate imposed water stress in pure culture was examined in 55 isolates of 18 species. Water potential treatments, adjusted with polyethylene glycol, were applied to Petri dish units. These units allowed colony diameter measurements of fungi grown on liquid media. Delayed growth initiation and inhibition of growth...

Sensitivity of EAS measurements to the energy spectrum of muons

NASA Astrophysics Data System (ADS)

Espadanal, J.; Cazon, L.; Conceição, R.

2017-01-01

We have studied how the energy spectrum of muons at production affects some of the most common measurements related to muons in extensive air shower studies, namely, the number of muons at the ground, the slope of the lateral distribution of muons, the apparent muon production depth, and the arrival time delay of muons at ground. We found that by changing the energy spectrum by an amount consistent with the difference between current models (namely EPOS-LHC and QGSJET-II.04), the muon surface density at ground increases 5% at 20° zenith angle and 17% at 60° zenith angle. This effect introduces a zenith angle dependence on the reconstructed number of muons which might be experimentally observed. The maximum of the muon production depth distribution at 40° increases ∼ 10 g/cm2 and ∼ 0 g/cm2 at 60°, which, from pure geometrical considerations, increases the arrival time delay of muons. There is an extra contribution to the delay due to the subluminal velocities of muons of the order of ∼ 3 ns at all zenith angles. Finally, changes introduced in the logarithmic slope of the lateral density function are less than 2%.

Measuring Procrastination: Psychometric Properties of the Norwegian Versions of the Irrational Procrastination Scale (IPS) and the Pure Procrastination Scale (PPS)

ERIC Educational Resources Information Center

Svartdal, Frode

2017-01-01

Procrastination has been defined in different ways. Two instruments--the Irrational Procrastination Scale (IPS) and the Pure Procrastination Scale (PPS)--focus on a core problem in procrastination--the irrational delay of intended behavior. The present paper examined the psychometric properties of the Norwegian translations of these scales. In…

Dynamic regulation of heart rate during acute hypotension: new insight into baroreflex function

NASA Technical Reports Server (NTRS)

Zhang, R.; Behbehani, K.; Crandall, C. G.; Zuckerman, J. H.; Levine, B. D.; Blomqvist, C. G. (Principal Investigator)

2001-01-01

To examine the dynamic properties of baroreflex function, we measured beat-to-beat changes in arterial blood pressure (ABP) and heart rate (HR) during acute hypotension induced by thigh cuff deflation in 10 healthy subjects under supine resting conditions and during progressive lower body negative pressure (LBNP). The quantitative, temporal relationship between ABP and HR was fitted by a second-order autoregressive (AR) model. The frequency response was evaluated by transfer function analysis. Results: HR changes during acute hypotension appear to be controlled by an ABP error signal between baseline and induced hypotension. The quantitative relationship between changes in ABP and HR is characterized by a second-order AR model with a pure time delay of 0.75 s containing low-pass filter properties. During LBNP, the change in HR/change in ABP during induced hypotension significantly decreased, as did the numerator coefficients of the AR model and transfer function gain. Conclusions: 1) Beat-to-beat HR responses to dynamic changes in ABP may be controlled by an error signal rather than directional changes in pressure, suggesting a "set point" mechanism in short-term ABP control. 2) The quantitative relationship between dynamic changes in ABP and HR can be described by a second-order AR model with a pure time delay. 3) The ability of the baroreflex to evoke a HR response to transient changes in pressure was reduced during LBNP, which was due primarily to a reduction of the static gain of the baroreflex.

Myelodysplastic syndrome in an infant with constitutional pure duplication 1q41-qter.

PubMed

Morokawa, Hirokazu; Kamiya, Motoko; Wakui, Keiko; Kobayashi, Mikiko; Kurata, Takashi; Matsuda, Kazuyuki; Kawamura, Rie; Kanno, Hiroyuki; Fukushima, Yoshimitsu; Nakazawa, Yozo; Kosho, Tomoki

2018-01-01

We report on a Japanese female infant as the fourth patient with the constitutional pure duplication 1q41-qter confirmed by chromosomal microarray and as the first who developed myelodysplastic syndrome (MDS) among those with the constitutional 1q duplication. Common clinical features of the constitutional pure duplication 1q41-qter include developmental delay, craniofacial characteristics, foot malformation, hypertrichosis, and respiratory insufficiency. The association between MDS and the duplication of the genes in the 1q41-qter region remains unknown.

New topics in coherent anti-stokes raman scattering gas-phase diagnostics : femtosecond rotational CARS and electric-field measurements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lempert, Walter R.; Barnat, Edward V.; Kearney, Sean Patrick

2010-07-01

We discuss two recent diagnostic-development efforts in our laboratory: femtosecond pure-rotational Coherent anti-Stokes Raman scattering (CARS) for thermometry and species detection in nitrogen and air, and nanosecond vibrational CARS measurements of electric fields in air. Transient pure-rotational fs-CARS data show the evolution of the rotational Raman polarization in nitrogen and air over the first 20 ps after impulsive pump/Stokes excitation. The Raman-resonant signal strength at long time delays is large, and we additionally observe large time separation between the fs-CARS signatures of nitrogen and oxygen, so that the pure-rotational approach to fs-CARS has promise for simultaneous species and temperature measurementsmore » with suppressed nonresonant background. Nanosecond vibrational CARS of nitrogen for electric-field measurements is also demonstrated. In the presence of an electric field, a dipole is induced in the otherwise nonpolar nitrogen molecule, which can be probed with the introduction of strong collinear pump and Stokes fields, resulting in CARS signal radiation in the infrared. The electric-field diagnostic is demonstrated in air, where the strength of the coherent infrared emission and sensitivity our field measurements is quantified, and the scaling of the infrared signal with field strength is verified.« less

First-line nitrosourea-based chemotherapy in symptomatic non-resectable supratentorial pure low-grade astrocytomas.

PubMed

Frenay, M P; Fontaine, D; Vandenbos, F; Lebrun, C

2005-09-01

At the present time, there are no proven beneficial effects of chemotherapy (CT) for the treatment of pure low-grade astrocytomas. Brain radiotherapy (RT) still remains the standard treatment in order to reduce or delay tumor progression or symptoms, despite possible long-term neurologic complications. We report 10 patients, with histologically proven pure low-grade fibrillary astrocytomas, to which we administered a first-line nitrosourea-based CT. All patients were symptomatic with pharmaco-resistant epilepsy or neurologic symptoms, and had been rejected for neurosurgical resection. All patients with epilepsy had a clinical improvement with reduction in seizure frequency and 60% became seizure-free. CT was well tolerated; all patients developed myelosuppression with 40% of grade III/IV hematotoxicity. Seven were alive at the time of writing with a mean follow-up of 6.5 years (3.5-12) from first recorded symptoms. The three deceased patients died 7.5, 7.5, and 8.5 years from first symptoms. These results demonstrate that some patients with symptomatic non-resectable fibrillary low-grade astrocytomas can be treated with up-front CT to improve their neurologic status. This report suggests that benefits of CT on symptoms, survival, and quality of life should be prospectively compared with RT.

Two facets of patience in young children: Waiting with and without an explicit reward.

PubMed

Barragan-Jason, Gladys; Atance, Cristina; Kopp, Leia; Hopfensitz, Astrid

2018-07-01

Patience, or the ability to tolerate delay, is typically studied using delay of gratification (DoG) tasks. However, among other factors (e.g., type of reward), the use of a reward to test patience is affected by an individual's motivation to obtain the reward (e.g., degree of preference for the small vs. large reward). In addition, DoG tasks do not assess the extent to which an individual can wait in the absence of an explicit reward-or what we term "patience as a virtue." Accordingly, the current study used a new measure of patience-the "pure waiting paradigm"-in which 3- to 5-year-old children waited 3 min with nothing to do and with no explicit reward. We then examined the relation between performance on this task (as assessed by children's spontaneous patient behaviors) and performance on two DoG tasks (candy and video rewards). Significant correlations were found between DoG performance and patient behaviors in the pure waiting paradigm, especially when controlling for motivation. These results and methodology show for the first time a direct link between patience as a virtue and DoG performance and also provide new insights about the study of patience in children. Copyright © 2018 Elsevier Inc. All rights reserved.

Inhibition-of-return at multiple locations in visual space.

PubMed

Wright, R D; Richard, C M

1996-09-01

Inhibition-of-return is thought to be a visual search phenomenon characterized by delayed responses to targets presented at recently cued or recently fixated locations. We studied this inhibition effect following the simultaneous presentation of multiple location cues. The results indicated that response inhibition can be associated with as many as four locations at the same time. This suggests that a purely oculomotor account of inhibition-of-return is oversimplified. In short, although oculomotor processes appear to play a role in inhibition-of-return they may not tell the whole story about how it occurs because we can only program and execute eye movements to one location at a time.

Singlet and triplet energy transfer in a benzil-doped, light emitting, solid-state conjugated polymer

NASA Astrophysics Data System (ADS)

Rothe, C.; Pålsson, L. O.; Monkman, A. P.

2002-12-01

The luminescence emitted from pure and benzil-doped thin films of the conjugated polymer polyfluorene [PF2/6] are compared. The prompt fluorescence from the first singlet-excited state of the polymer is quenched by 90% in the presence of 10% per weight benzil. In addition to the prompt fluorescence, time-resolved spectroscopy at low temperature also allows the detection of phosphorescence and delayed fluorescence from the host polymer. Again the delayed fluorescence is strongly quenched but the phosphorescence is enhanced in doped samples. An explanation of the results is given in terms of singlet energy transfer from the host to benzil and triplet energy transfer from the dopant back to PF2/6. We have applied this to enable better understanding of the photophysics in PF2/6 doped with a platinum porphyrin complex.

New Molecular Design Concurrently Providing Superior Pure Blue, Thermally Activated Delayed Fluorescence and Optical Out-Coupling Efficiencies.

PubMed

Rajamalli, P; Senthilkumar, N; Huang, P-Y; Ren-Wu, C-C; Lin, H-W; Cheng, C-H

2017-08-16

Simultaneous enhancement of out-coupling efficiency, internal quantum efficiency, and color purity in thermally activated delayed fluorescence (TADF) emitters is highly desired for the practical application of these materials. We designed and synthesized two isomeric TADF emitters, 2DPyM-mDTC and 3DPyM-pDTC, based on di(pyridinyl)methanone (DPyM) cores as the new electron-accepting units and di(tert-butyl)carbazole (DTC) as the electron-donating units. 3DPyM-pDTC, which is structurally nearly planar with a very small ΔE ST , shows higher color purity, horizontal ratio, and quantum yield than 2DPyM-mDTC, which has a more flexible structure. An electroluminescence device based on 3DPyM-pDTC as the dopant emitter can reach an extremely high external quantum efficiency of 31.9% with a pure blue emission. This work also demonstrates a way to design materials with a high portion of horizontal molecular orientation to realize a highly efficient pure-blue device based on TADF emitters.

The combustion of pure and composite propellants - The expansion and application of laminar flame theory to heterogeneous solid propellants.

NASA Technical Reports Server (NTRS)

Hertzberg, M.

1971-01-01

Development of a combustion theory based on the laminarized solutions to the energy and flow conservation equations, which is more realistic in recognizing the nature of the heating-rate problem and in obtaining a practical solution to estimating its magnitude. A new experimental approach is used for studying the combustion behavior of pure monopropellants and composite propellants which uses a laser beam to supply additional heat feedback to a burning surface. New experimental data are presented for the laser-induced combustion rate and ignition delay of pure ammonium perchlorate. The pure monopropellant theory is generalized to include such nonadiabatic effects, and the new experimental data are in good agreement with the nonadiabatic theory.-

Thermally activated delayed fluorescence of fluorescein derivative for time-resolved and confocal fluorescence imaging.

PubMed

Xiong, Xiaoqing; Song, Fengling; Wang, Jingyun; Zhang, Yukang; Xue, Yingying; Sun, Liangliang; Jiang, Na; Gao, Pan; Tian, Lu; Peng, Xiaojun

2014-07-09

Compared with fluorescence imaging utilizing fluorophores whose lifetimes are in the order of nanoseconds, time-resolved fluorescence microscopy has more advantages in monitoring target fluorescence. In this work, compound DCF-MPYM, which is based on a fluorescein derivative, showed long-lived luminescence (22.11 μs in deaerated ethanol) and was used in time-resolved fluorescence imaging in living cells. Both nanosecond time-resolved transient difference absorption spectra and time-correlated single-photon counting (TCSPC) were employed to explain the long lifetime of the compound, which is rare in pure organic fluorophores without rare earth metals and heavy atoms. A mechanism of thermally activated delayed fluorescence (TADF) that considers the long wavelength fluorescence, large Stokes shift, and long-lived triplet state of DCF-MPYM was proposed. The energy gap (ΔEST) of DCF-MPYM between the singlet and triplet state was determined to be 28.36 meV by the decay rate of DF as a function of temperature. The ΔE(ST) was small enough to allow efficient intersystem crossing (ISC) and reverse ISC, leading to efficient TADF at room temperature. The straightforward synthesis of DCF-MPYM and wide availability of its starting materials contribute to the excellent potential of the compound to replace luminescent lanthanide complexes in future time-resolved imaging technologies.

The Recrystallization Behavior of Unalloyed Mg and a Mg-Al Alloy

NASA Astrophysics Data System (ADS)

Murphy, Aeriel D.; Allison, John E.

2018-02-01

The static recrystallization behavior of pure Mg and Mg-4Al was characterized over a range of annealing temperatures. The electron backscatter diffraction grain orientation spread technique was used to quantify the level of recrystallization at various annealing times. Recrystallization kinetics were characterized using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) relationship and it was found that two sequential annealing stages exist. Stage 1 involves heterogeneous nucleation of recrystallization in regions with a high stored energy, including twins and grain boundaries, and can be represented by an Avrami exponent of n 1 ranging from 0.35 to 0.6. During Stage 2, recrystallization occurred predominately in the interior of deformed grains with incomplete recrystallization generally observed even at annealing times in excess of two weeks. The second recrystallization stage exhibited a much lower Avrami exponent, n 2, ranging from 0.02 to 0.2. Increasing the starting grain size in the pure Mg condition led to a significant delay in recrystallization. The addition of Al had a minimal effect on the recrystallization kinetics of Mg.

Symptom Dimensions of Depression and Apathy and Their Relationship With Cognition in Parkinson's Disease.

PubMed

Szymkowicz, Sarah M; Dotson, Vonetta M; Jones, Jacob D; Okun, Michael S; Bowers, Dawn

2018-03-01

Both depression and apathy, alone and in combination, have been shown to negatively affect cognition in patients with Parkinson's disease (PD). However, the influence of specific symptom dimensions of depression and apathy on cognition is not well understood. The current study investigated the relationship between symptom dimensions of depression and apathy, based on factors identified in Kirsch-Darrow et al. (2011), and memory and executive function in PD. A sample of 138 non-demented individuals with PD (mean age=64.51±7.43 years) underwent neuropsychological testing and completed the Beck Depression Inventory, 2nd Edition, and Apathy Scale. Separate hierarchical regression models examined the relationship between symptom dimensions of depression and apathy ("pure" depressive symptoms, "pure" apathy, loss of interest/pleasure [anhedonia], and somatic symptoms) and three cognitive domain composites: immediate verbal memory, delayed verbal memory, and executive function. After adjusting for general cognitive status and the influence of the other symptom dimensions, "pure" depressive symptoms were negatively associated with the delayed verbal memory composite (p<.034) and somatic symptoms were positively associated with the executive function composite (p<.026). No symptom dimensions were significantly related to the immediate verbal memory composite. Findings suggest that specific mood symptoms are associated with delayed verbal memory and executive function performance in non-demented patients with PD. Further research is needed to better understand possible mechanisms through which specific symptom dimensions of depression and apathy are associated with cognition in PD. (JINS, 2018, 24, 269-282).

Effect of viewing distance and location of the axis of head rotation on the monkey's vestibuloocular reflex. I. Eye movement responses.

PubMed

Snyder, L H; King, W M

1992-04-01

1. The vestibuloocular reflex (VOR) stabilizes images on the retina against movements of the head in space. Viewing distance, target eccentricity, and location of the axis of rotation may influence VOR responses because rotation of the head about most axes in space rotates and translates the eyes relative to visual targets. To study the VOR response to combined rotation and translation, monkeys were placed on a rate table and rotated briefly in the dark about a vertical axis that was located in front of or behind the eyes. The monkeys fixated a near or far visual target that was extinguished before the rotation. Eye movements were recorded from both eyes by the use of the search coil technique. 2. Peak eye velocity evoked by the VOR was linearly related to vergence angle for any axis of rotation. The percent change in the VOR with near target viewing relative to far target viewing at a vergence angle of 20 degrees was linearly related to the location of the axis of rotation. Axes located behind the eyes produced positive changes in VOR amplitude, and axes located in front of the eyes produced negative changes in VOR amplitude. An axis of rotation located in the coronal plane containing the centers of rotation of the eyes produced no modification of VOR amplitude. For any axis, the VOR compensated for approximately 90% of the translation of the eye relative to near targets. 3. The initial VOR response was not correct in magnitude but was refined by a series of three temporally delayed corrections of increasing complexity. The earliest VOR-evoked eye movement (10-20 ms after rotation onset) was independent of viewing distance and rotational axis location. In the next 100 ms, eye speed appeared to be sequentially modified three times: within 20 ms by viewing distance; within 30 ms by otolith translation; and within 100 ms by eye translation relative to the visual target. 4. These data suggest a formal model of the VOR consisting of four channels. Channel 1 conveys an unmodified head rotation signal with a pure delay of 10 ms. Channel 2 conveys an angular head velocity signal, modified by viewing distance with a pure delay of 20 ms, but invariant with respect to the location of the axis of rotation. Channel 3 conveys a linear head velocity signal, dependent on the location of the axis of rotation, that is modified by viewing distance with a pure delay of 30 ms.(ABSTRACT TRUNCATED AT 400 WORDS)

Mathematical properties and parameter estimation for transit compartment pharmacodynamic models.

PubMed

Yates, James W T

2008-07-03

One feature of recent research in pharmacodynamic modelling has been the move towards more mechanistically based model structures. However, in all of these models there are common sub-systems, such as feedback loops and time-delays, whose properties and contribution to the model behaviour merit some mathematical analysis. In this paper a common pharmacodynamic model sub-structure is considered: the linear transit compartment. These models have a number of interesting properties as the length of the cascade chain is increased. In the limiting case a pure time-delay is achieved [Milsum, J.H., 1966. Biological Control Systems Analysis. McGraw-Hill Book Company, New York] and the initial behaviour becoming increasingly sensitive to parameter value perturbation. It is also shown that the modelled drug effect is attenuated, though the duration of action is longer. Through this analysis the range of behaviours that such models are capable of reproducing are characterised. The properties of these models and the experimental requirements are discussed in order to highlight how mathematical analysis prior to experimentation can enhance the utility of mathematical modelling.

Lowering of the firing voltage and reducing of the discharge delay time in alternating current plasma display panels by a discontinuous spin-coated LaB{sub 6} film on the MgO protective layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deng, Jiang, E-mail: dj78291@163.com; Zeng, Baoqing; Zhongshan Institute, University of Electronic Science and Technology of China, 528402 zhongshan

2014-03-15

A spin coated LaB{sub 6} discontinuous film is covered on MgO protective layer to improve the discharge performance of alternating current plasma display panels. Under the premise of high transmittance of more than 90%, a very small amount of polycrystal LaB{sub 6} powders added in an organic solvent are chosen as the coating solution. The discharge characteristics results show that with 250 torr 5% Xe-Ne pressure, the firing voltage and discharge delay time of the test panel with LaB{sub 6}/MgO double protective layer are decreased by 13.4% and 36.5%, respectively, compared with that of conventional MgO protective layer, likely owingmore » to the low work function of LaB{sub 6.} Furthermore, the aging time of the proposed structure is comparable to that of pure MgO protective layer. Therefore, it will not increase the production costs and is highly suitable to be applied for alternating current plasma display panels with low electrical power consumption.« less

Synergistic hydrate inhibition of monoethylene glycol with poly(vinylcaprolactam) in thermodynamically underinhibited system.

PubMed

Kim, Jakyung; Shin, Kyuchul; Seo, Yutaek; Cho, Seong Jun; Lee, Ju Dong

2014-07-31

This study investigates the hydrate inhibition performance of monoethylene glycol (MEG) with poly(vinylcaprolactam) (PVCap) for retarding the hydrate onset as well as preventing the agglomeration of hydrate particles. A high-pressure autoclave was used to determine the hydrate onset time, subcooling temperature, hydrate fraction in the liquid phase, and torque changes during hydrate formation in pure water, 0.2 wt % PVCap solution, and 20 and 30 wt % MEG solutions. In comparison to water with no inhibitors, the addition of PVCap delays the hydrate onset time but cannot reduce the hydrate fraction, leading to a sharp increase in torque. The 20 and 30 wt % MEG solutions also delay the hydrate onset time slightly and reduce the hydrate fraction to 0.15. The addition of 0.2 wt % PVCap to the 20 wt % MEG solution, however, delays the hydrate onset time substantially, and the hydrate fraction was less than 0.19. The torque changes were negligible during the hydrate formation, suggesting the homogeneous dispersion of hydrate particles in the liquid phase. The well-dispersed hydrate particles do not agglomerate or deposit under stirring. Moreover, when 0.2 wt % PVCap was added to the 30 wt % MEG solution, no hydrate formation was observed for at least 24 h. These results suggest that mixing of MEG with a small amount of PVCap in underinhibited conditions will induce the synergistic inhibition of hydrate by delaying the hydrate onset time as well as preventing the agglomeration and deposition of hydrate particles. Decreasing the hydrate fraction in the liquid phase might be the reason for negligible torque changes during the hydrate formation in the 0.2 wt % PVCap and 20 wt % MEG solution. Simple structure II was confirmed by in situ Raman spectroscopy for the synergistic inhibition system, while coexisting structures I and II are observed in 0.2 wt % PVCap solution.

Formulation reproducing the ignition delays simulated by a detailed mechanism: Application to n-heptane combustion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Imbert, Bruno; Lafosse, Fabien; Catoire, Laurent

2008-11-15

This article is part of the project to model the kinetics of high-temperature combustions, occurring behind shock waves and in detonation waves. The ''conventional'' semi-empirical correlations of ignition delays have been reformulated, by keeping the Arrhenius equation form. It is shown how a polynomial with 3{sup N} coefficients (where N element of is the number of adjustable kinetic parameters, likely to be simultaneously chosen among the temperature T, the pressure P, the inert fraction X{sub Ar}, and the equivalence ratio {phi}) can reproduce the delays predicted by the Curran et al. [H.J. Curran, P. Gaffuri, W.J. Pitz, C.K. Westbrook, Combust.more » Flame 129 (2002) 253-280] detailed mechanism (565 species and 2538 reactions), over a wide range of conditions (comparable with the validity domain). The deviations between the simulated times and their fits (typically 1%) are definitely lower than the uncertainties related to the mechanism (at least 25%). In addition, using this new formalism to evaluate these durations is about 10{sup 6} times faster than simulating them with SENKIN (CHEMKIN III package) and only 10 times slower than using the classical correlations. The adaptation of the traditional method for predicting delays is interesting for modeling, because those performances are difficult to obtain simultaneously with other reduction methods (either purely mathematical, chemical, or even mixed). After a physical and mathematical justification of the proposed formalism, some of its potentialities for n-heptane combustion are presented. In particular, the trends of simulated delays and activation energies are shown for {sub T} {sub element} {sub of} {sub [1500} {sub K,1900} {sub K},} {sub P} {sub element} {sub of} {sub [10kPa,1MPa]}, X{sub Ar} element of [0,0.7], and {phi} element of {sub [0.25,4.0]}. (author)« less

Femtosecond buildup of phonon-plasmon coupling in photoexcited InP observed by ultrabroadband THz probing

NASA Astrophysics Data System (ADS)

Huber, Rupert; Kübler, Carl; Tübel, Stefan; Leitenstorfer, Alfred

2006-02-01

We study the ultrafast transition of a pure longitudinal optical phonon resonance to a coupled phonon-plasmon system. Following 10-fs photoexcitation of intrinsic indium phosphide, ultrabroadband THz opto-electronics monitors the buildup of coherent beats of the emerging hybrid modes directly in the time domain with sub-cycle resolution. Mutual repulsion and redistribution of the oscillator strength of the interacting phonons and plasmons are seen to emerge on a delayed femtosecond time scale. Both branches of the mixed modes are monitored for various excitation densities N. We observe a pronounced anticrossing of the coupled resonances as a function of N. The characteristic formation time for phonon-plasmon coupling exhibits density dependence. The time is approximately set by one oscillation cycle of the upper branch of the mixed modes.

Heavy Atom Effect of Bromine Significantly Enhances Exciton Utilization of Delayed Fluorescence Luminogens.

PubMed

Gan, Shifeng; Hu, Shimin; Li, Xiang-Long; Zeng, Jiajie; Zhang, Dongdong; Huang, Tianyu; Luo, Wenwen; Zhao, Zujin; Duan, Lian; Su, Shi-Jian; Tang, Ben Zhong

2018-05-23

Raising triplet exciton utilization of pure organic luminescent materials is of significant importance for efficiency advancement of organic light-emitting diodes (OLEDs). Herein, by introducing bromine atom(s) onto a typical molecule (bis(carbazol-9-yl)-4,5-dicyanobenzene) with thermally activated delayed fluorescence, we demonstrate that the heavy atom effect of bromine can increase spin-orbit coupling and promote the reverse intersystem crossing, which endow the molecules with more distinct delayed fluorescence. In consequence, the triplet exciton utilization is improved greatly with the increase of bromine atoms, affording apparently advanced external quantum efficiencies of OLEDs. Utilizing the enhancement effect of bromine atoms on delayed fluorescence should be a simple and promising design concept for efficient organic luminogens with high exciton utilization.

Robust control of integrated motor-transmission powertrain system over controller area network for automotive applications

NASA Astrophysics Data System (ADS)

Zhu, Xiaoyuan; Zhang, Hui; Cao, Dongpu; Fang, Zongde

2015-06-01

Integrated motor-transmission (IMT) powertrain system with directly coupled motor and gearbox is a good choice for electric commercial vehicles (e.g., pure electric buses) due to its potential in motor size reduction and energy efficiency improvement. However, the controller design for powertrain oscillation damping becomes challenging due to the elimination of damping components. On the other hand, as controller area network (CAN) is commonly adopted in modern vehicle system, the network-induced time-varying delays that caused by bandwidth limitation will further lead to powertrain vibration or even destabilize the powertrain control system. Therefore, in this paper, a robust energy-to-peak controller is proposed for the IMT powertrain system to address the oscillation damping problem and also attenuate the external disturbance. The control law adopted here is based on a multivariable PI control, which ensures the applicability and performance of the proposed controller in engineering practice. With the linearized delay uncertainties characterized by polytopic inclusions, a delay-free closed-loop augmented system is established for the IMT powertrain system under discrete-time framework. The proposed controller design problem is then converted to a static output feedback (SOF) controller design problem where the feedback control gains are obtained by solving a set of linear matrix inequalities (LMIs). The effectiveness as well as robustness of the proposed controller is demonstrated by comparing its performance against that of a conventional PI controller.

Digital signal processor and processing method for GPS receivers

NASA Technical Reports Server (NTRS)

Thomas, Jr., Jess B. (Inventor)

1989-01-01

A digital signal processor and processing method therefor for use in receivers of the NAVSTAR/GLOBAL POSITIONING SYSTEM (GPS) employs a digital carrier down-converter, digital code correlator and digital tracking processor. The digital carrier down-converter and code correlator consists of an all-digital, minimum bit implementation that utilizes digital chip and phase advancers, providing exceptional control and accuracy in feedback phase and in feedback delay. Roundoff and commensurability errors can be reduced to extremely small values (e.g., less than 100 nanochips and 100 nanocycles roundoff errors and 0.1 millichip and 1 millicycle commensurability errors). The digital tracking processor bases the fast feedback for phase and for group delay in the C/A, P.sub.1, and P.sub.2 channels on the L.sub.1 C/A carrier phase thereby maintaining lock at lower signal-to-noise ratios, reducing errors in feedback delays, reducing the frequency of cycle slips and in some cases obviating the need for quadrature processing in the P channels. Simple and reliable methods are employed for data bit synchronization, data bit removal and cycle counting. Improved precision in averaged output delay values is provided by carrier-aided data-compression techniques. The signal processor employs purely digital operations in the sense that exactly the same carrier phase and group delay measurements are obtained, to the last decimal place, every time the same sampled data (i.e., exactly the same bits) are processed.

Validation of a French version of the pure procrastination scale (PPS).

PubMed

Rebetez, Marie My Lien; Rochat, Lucien; Gay, Philippe; Van der Linden, Martial

2014-08-01

Procrastination is a widespread phenomenon that affects everyone's day-to-day life and interferes with the clinical treatment of several psychopathological states. To assess this construct, Steel (2010) developed the Pure Procrastination Scale (PPS), a short scale intended to capture the general notion of dysfunctional delay. The aim of the current study was to present a French version of this questionnaire. To this end, the 12 items of the PPS were translated into French and data were collected from an online survey in a sample of 245 French-speaking individuals from the general population. The results revealed that one item had problematic face validity; it was therefore removed. Exploratory and confirmatory analyses performed on the resulting 11-item version of the French PPS indicated that the scale was composed of two factors ("voluntary delay" and "observed delay") depending on a common, higher-order construct ("general procrastination"). Good internal consistency and test-retest reliability were found. External validity was supported by specific relationships with measures of personality traits, impulsivity, and subjective well-being. The French PPS therefore presents satisfactory psychometric properties and may be considered a reliable and valid instrument for research, teaching and clinical practice. Copyright © 2014 Elsevier Inc. All rights reserved.

Comparative Ethanol-Induced Potentiation of Stimulatory Responses to Dexmethylphenidate Versus Methylphenidate.

PubMed

Patrick, Kennerly S; Straughn, Arthur B; Reeves, Owen T; Bernstein, Hilary; Malcolm, Robert

2015-08-01

The potentiation of positive subjective responses to immediate-release dexmethylphenidate (d-MPH) or dl-methylphenidate (dl-MPH) by ethanol was investigated over the time course of maximal drug exposure after a single dose. In a 4-way, randomized, crossover study design, 12 men and 12 women normal volunteers received d-MPH (0.15 mg/kg) or dl-MPH (0.3 mg/kg) with or without ethanol (0.6 g/kg). Serial visual analog scales were used as surrogates for drug abuse liability ("high," "good," "like," "stimulated," and "any drug effect"). Combining pure d-MPH with ethanol significantly (P < 0.005) increased the area under the effect curves (AUC(0-5.25h)) of all 5 subscales. The dl-MPH-ethanol combination significantly (P < 0.05) increased these AUCs with the exception of like (P = 0.08). Effects of the pure d-MPH-ethanol combination exhibited delayed potentiation relative to dl-MPH-ethanol. A pharmacokinetic interaction between the l-isomer of dl-MPH and ethanol has previously been shown to increase early exposure to d-MPH. Administration of the pure isomer d-MPH precludes this absorption phase pharmacokinetic interaction with ethanol. This notwithstanding, the pure d-MPH-ethanol combination resulted in comparable, if not greater, cumulative stimulant potentiation than the dl-MPH-ethanol combination. These findings provide evidence of a pharmacodynamic component to d-MPH-ethanol synergistic interactions and carry implications for the rational drug individualization in the treatment of attention-deficit/hyperactivity disorder.

Assessment of simulation fidelity using measurements of piloting technique in flight. II

NASA Technical Reports Server (NTRS)

Ferguson, S. W.; Clement, W. F.; Hoh, R. H.; Cleveland, W. B.

1985-01-01

Two components of the Vertical Motion Simulator (presently being used to assess the fidelity of UH-60A simulation) are evaluated: (1) the dash/quickstop Nap-of-the-earth (NOE) piloting task, and (2) the bop-up task. Data from these two flight test experiments are presented which provide information on the effect of reduced visual field of view, variation in scene content and texture, and the affect of pure time delay in the closed-loop pilot response. In comparison with task performance results obtained in flight tests, the results from the simulation indicate that the pilot's NOE task performance in the simulator is significantly degraded.

Interaural time sensitivity of high-frequency neurons in the inferior colliculus.

PubMed

Yin, T C; Kuwada, S; Sujaku, Y

1984-11-01

Recent psychoacoustic experiments have shown that interaural time differences provide adequate cues for lateralizing high-frequency sounds, provided the stimuli are complex and not pure tones. We present here physiological evidence in support of these findings. Neurons of high best frequency in the cat inferior colliculus respond to interaural phase differences of amplitude modulated waveforms, and this response depends upon preservation of phase information of the modulating signal. Interaural phase differences were introduced in two ways: by interaural delays of the entire waveform and by binaural beats in which there was an interaural frequency difference in the modulating waveform. Results obtained with these two methods are similar. Our results show that high-frequency cells can respond to interaural time differences of amplitude modulated signals and that they do so by a sensitivity to interaural phase differences of the modulating waveform.

Ignition delays, heats of combustion, and reaction rates of aluminum alkyl derivatives used as ignition and combustion enhancers for supersonic combustors

NASA Technical Reports Server (NTRS)

Ryan, T. W., III; Harlowe, W. W.; Schwab, S.

1992-01-01

The work was based on adapting an apparatus and procedure developed at Southwest Research Institute for rating the ignition quality of fuels for diesel engines. Aluminum alkyls and various Lewis-base adducts of these materials, both neat and mixed 50/50 with pure JP-10 hydrocarbon, were injected into the combustion bomb using a high-pressure injection system. The bomb was pre-charged with air that was set at various initial temperatures and pressures for constant oxygen density. The ignition delay times were determined for the test materials at these different initial conditions. The data are presented in absolute terms as well as comparisons with the parent alkyls. The relative heats of reaction of the various test materials were estimated based on a computation of the heat release, using the pressure data recorded during combustion in the bomb. In addition, the global reaction rates for each material were compared at a selected tmperature and pressure.

Comparative pharmacokinetic study of mangiferin after oral administration of pure mangiferin and US patented polyherbal formulation to rats.

PubMed

Kammalla, Ananth Kumar; Ramasamy, Mohan Kumar; Inampudi, Jyothi; Dubey, Govind Prasad; Agrawal, Aruna; Kaliappan, Ilango

2015-04-01

The US patented polyherbal formulation for the prevention and management of type II diabetes and its vascular complications was used for the present study. The xanthone glycoside mangiferin is one of the major effector constituents in the Salacia species with potential anti-diabetic activity. The pharmacokinetic differences of mangiferin following oral administration of pure mangiferin and polyherbal formulation containing Salacia species were studied with approximately the same dose 30 mg/kg mangiferin and its distribution among the major tissue in Wistar rats. Plasma samples were collected at different time points (15, 30, 60, 120, 180, 240, 360, 480, 600, 1,440, 2,160, and 2880 min) and subsequently analyzed using a validated simple and rapid LC-MS method. Plasma concentration versus time profiles were explored by non-compartmental analysis. Mangiferin plasma exposure was significantly increased when administered from formulation compared to the standard mangiferin. Mangiferin resided significantly longer in the body (last mean residence time (MRTlast)) when given in the form of the formulation (3.65 h). Cmax values of formulation (44.16 μg/mL) administration were elevated when compared to equivalent dose of the pure mangiferin (15.23 μg/mL). Tissue distribution study of mangiferin from polyherbal formulation was also studied. In conclusion, the exposure of mangiferin is enhanced after formulation and administration and could result in superior efficacy of polyherbal formulation when compared to an equivalent dose of mangiferin. The results indicate that the reason which delays the elimination of mangiferin and enhances its bioavailability might the interactions of the some other constituents present in the polyherbal formulation. Distribution study results indicate that mangiferin was extensively bound to the various tissues like the small intestine, heart, kidney, spleen, and liver except brain tissue.

Effectiveness of Interaural Delays Alone as Cues During Dynamic Sound Localization

NASA Technical Reports Server (NTRS)

Wenzel, Elizabeth M.; Null, Cynthia H. (Technical Monitor)

1996-01-01

The contribution of interaural time differences (ITDs) to the localization of virtual sound sources with and without head motion was examined. Listeners estimated the apparent azimuth, elevation and distance of virtual sources presented over headphones. Stimuli (3 sec., white noise) were synthesized from minimum-phase representations of nonindividualized head-related transfer functions (HRTFs); binaural magnitude spectra were derived from the minimum phase estimates and ITDs were represented as a pure delay. During dynamic conditions, listeners were encouraged to move their heads; head position was tracked and stimuli were synthesized in real time using a Convolvotron to simulate a stationary external sound source. Two synthesis conditions were tested: (1) both interaural level differences (ILDs) and ITDs correctly correlated with source location and head motion, (2) ITDs correct, no ILDs (flat magnitude spectrum). Head movements reduced azimuth confusions primarily when interaural cues were correctly correlated, although a smaller effect was also seen for ITDs alone. Externalization was generally poor for ITD-only conditions and was enhanced by head motion only for normal HRTFs. Overall the data suggest that, while ITDs alone can provide a significant cue for azimuth, the errors most commonly associated with virtual sources are reduced by location-dependent magnitude cues.

Temperature measurements in metalized propellant combustion using hybrid fs/ps coherent anti-Stokes Raman scattering.

PubMed

Kearney, Sean P; Guildenbecher, Daniel R

2016-06-20

We apply ultrafast pure-rotational coherent anti-Stokes Raman scattering (CARS) for temperature and relative oxygen concentration measurements in the plume emanating from a burning, aluminized ammonium-perchlorate propellant strand. Combustion of these metal-based propellants is a particularly hostile environment for laser-based diagnostics, with intense background luminosity and scattering from hot metal particles as large as several hundred micrometers in diameter. CARS spectra that were previously obtained using nanosecond pulsed lasers in an aluminum-particle-seeded flame are examined and are determined to be severely impacted by nonresonant background, presumably as a result of the plasma formed by particulate-enhanced laser-induced breakdown. Introduction of femtosecond/picosecond (fs/ps) laser pulses improves CARS detection by providing time-gated elimination of strong nonresonant background interference. Single-laser-shot fs/ps CARS spectra were acquired from the burning propellant plume, with picosecond probe-pulse delays of 0 and 16 ps from the femtosecond pump and Stokes pulses. At zero delay, nonresonant background overwhelms the Raman-resonant spectroscopic features. Time-delayed probing results in the acquisition of background-free spectra that were successfully fit for temperature and relative oxygen content. Temperature probability densities and temperature/oxygen correlations were constructed from ensembles of several thousand single-laser-shot measurements with the CARS measurement volume positioned within 3 mm or less of the burning propellant surface. The results show that ultrafast CARS is a potentially enabling technology for probing harsh, particle-laden flame environments.

Temperature measurements in metalized propellant combustion using hybrid fs/ps coherent anti-Stokes Raman scattering

DOE PAGES

Kearney, Sean P.; Guildenbecher, Daniel R.

2016-06-20

We apply ultrafast pure-rotational coherent anti-Stokes Raman scattering (CARS) for temperature and relative oxygen concentration measurements in the plume emanating from a burning, aluminized ammonium-perchlorate propellant strand. Combustion of these metal-based propellants is a particularly hostile environment for laser-based diagnostics, with intense background luminosity and scattering from hot metal particles as large as several hundred micrometers in diameter. CARS spectra that were previously obtained using nanosecond pulsed lasers in an aluminum-particle-seeded flame are examined and are determined to be severely impacted by nonresonant background, presumably as a result of the plasma formed by particulate-enhanced laser-induced breakdown. Introduction of femtosecond/picosecond (fs/ps)more » laser pulses improves CARS detection by providing time-gated elimination of strong nonresonant background interference. Single-laser-shot fs/ps CARS spectra were acquired from the burning propellant plume, with picosecond probe-pulse delays of 0 and 16 ps from the femtosecond pump and Stokes pulses. At zero delay, nonresonant background overwhelms the Raman-resonant spectroscopic features. Time-delayed probing results in the acquisition of background-free spectra that were successfully fit for temperature and relative oxygen content. Temperature probability densities and temperature/oxygen correlations were constructed from ensembles of several thousand single-laser-shot measurements with the CARS measurement volume positioned within 3 mm or less of the burning propellant surface. Lastly, the results show that ultrafast CARS is a potentially enabling technology for probing harsh, particle-laden flame environments.« less

Temperature measurements in metalized propellant combustion using hybrid fs/ps coherent anti-Stokes Raman scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kearney, Sean P.; Guildenbecher, Daniel R.

We apply ultrafast pure-rotational coherent anti-Stokes Raman scattering (CARS) for temperature and relative oxygen concentration measurements in the plume emanating from a burning, aluminized ammonium-perchlorate propellant strand. Combustion of these metal-based propellants is a particularly hostile environment for laser-based diagnostics, with intense background luminosity and scattering from hot metal particles as large as several hundred micrometers in diameter. CARS spectra that were previously obtained using nanosecond pulsed lasers in an aluminum-particle-seeded flame are examined and are determined to be severely impacted by nonresonant background, presumably as a result of the plasma formed by particulate-enhanced laser-induced breakdown. Introduction of femtosecond/picosecond (fs/ps)more » laser pulses improves CARS detection by providing time-gated elimination of strong nonresonant background interference. Single-laser-shot fs/ps CARS spectra were acquired from the burning propellant plume, with picosecond probe-pulse delays of 0 and 16 ps from the femtosecond pump and Stokes pulses. At zero delay, nonresonant background overwhelms the Raman-resonant spectroscopic features. Time-delayed probing results in the acquisition of background-free spectra that were successfully fit for temperature and relative oxygen content. Temperature probability densities and temperature/oxygen correlations were constructed from ensembles of several thousand single-laser-shot measurements with the CARS measurement volume positioned within 3 mm or less of the burning propellant surface. Lastly, the results show that ultrafast CARS is a potentially enabling technology for probing harsh, particle-laden flame environments.« less

Thresholds of Auditory-Motor Coupling Measured with a Simple Task in Musicians and Non-Musicians: Was the Sound Simultaneous to the Key Press?

PubMed Central

van Vugt, Floris T.; Tillmann, Barbara

2014-01-01

The human brain is able to predict the sensory effects of its actions. But how precise are these predictions? The present research proposes a tool to measure thresholds between a simple action (keystroke) and a resulting sound. On each trial, participants were required to press a key. Upon each keystroke, a woodblock sound was presented. In some trials, the sound came immediately with the downward keystroke; at other times, it was delayed by a varying amount of time. Participants were asked to verbally report whether the sound came immediately or was delayed. Participants' delay detection thresholds (in msec) were measured with a staircase-like procedure. We hypothesised that musicians would have a lower threshold than non-musicians. Comparing pianists and brass players, we furthermore hypothesised that, as a result of a sharper attack of the timbre of their instrument, pianists might have lower thresholds than brass players. Our results show that non-musicians exhibited higher thresholds for delay detection (180±104 ms) than the two groups of musicians (102±65 ms), but there were no differences between pianists and brass players. The variance in delay detection thresholds could be explained by variance in sensorimotor synchronisation capacities as well as variance in a purely auditory temporal irregularity detection measure. This suggests that the brain's capacity to generate temporal predictions of sensory consequences can be decomposed into general temporal prediction capacities together with auditory-motor coupling. These findings indicate that the brain has a relatively large window of integration within which an action and its resulting effect are judged as simultaneous. Furthermore, musical expertise may narrow this window down, potentially due to a more refined temporal prediction. This novel paradigm provides a simple test to estimate the temporal precision of auditory-motor action-effect coupling, and the paradigm can readily be incorporated in studies investigating both healthy and patient populations. PMID:24498299

Performance analysis of replication ALOHA for fading mobile communications channels

NASA Technical Reports Server (NTRS)

Yan, Tsun-Yee; Clare, Loren P.

1986-01-01

This paper describes an ALOHA random access protocol for fading communications channels. A two-state Markov model is used for the channel error process to account for the channel fading memory. The ALOHA protocol is modified to send multiple contiguous copies of a message at each transmission attempt. Both pure and slotted ALOHA channels are considered. The analysis is applicable to fading environments where the channel memory is short compared to the propagation delay. It is shown that smaller delay may be achieved using replications and, in noisy conditions, can also improve throughput.

Communication: hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering thermometry using a narrowband time-asymmetric probe pulse.

PubMed

Stauffer, Hans U; Miller, Joseph D; Roy, Sukesh; Gord, James R; Meyer, Terrence R

2012-03-21

A narrowband, time-asymmetric probe pulse is introduced into the hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering (fs/ps RCARS) technique to provide accurate and precise single-shot, high-repetition-rate gas-phase thermometric measurements. This narrowband pulse-generated by inserting a Fabry-Pérot étalon into the probe-pulse beam path-enables frequency-domain detection of pure-rotational transitions. The unique time-asymmetric nature of this pulse, in turn, allows for detection of resonant Raman-active rotational transitions free of signal contamination by nonresonant four-wave-mixing processes while still allowing detection at short probe-pulse delays, where collisional dephasing processes are negligible. We demonstrate that this approach provides excellent single-shot thermometric accuracy (<1% error) and precision (~2.5%) in gas-phase environments. © 2012 American Institute of Physics

Pathogenesis, diagnosis and treatment of cerebral fat embolism.

PubMed

Zhou, Yihua; Yuan, Ying; Huang, Chahua; Hu, Lihua; Cheng, Xiaoshu

2015-01-01

In this study, we analyzed two cases of pure cerebral fat embolism and reviewed related literatures to explore the pathogenesis, clinical manifestations, diagnosis and treatment of cerebral fat embolism, improve the treatment efficiency and reduce the misdiagnosis rate. In our cases, patients fully returned to consciousness at the different times with good prognosis, normal vital signs and without obvious sequelae. For patients with the limb fractures, who developed coma without chest distress, dyspnea or other pulmonary symptoms 12 or 24 h post injury, cerebral fat embolism should be highly suspected, except for those with intracranial lesions, such as delayed traumatic intracerebral hemorrhage, etc. The early diagnosis and comprehensive treatment can improve prognosis.

Hyperpolarization without persistent radicals for in vivo real-time metabolic imaging

PubMed Central

Eichhorn, Tim R.; Takado, Yuhei; Salameh, Najat; Capozzi, Andrea; Cheng, Tian; Hyacinthe, Jean-Noël; Mishkovsky, Mor; Roussel, Christophe; Comment, Arnaud

2013-01-01

Hyperpolarized substrates prepared via dissolution dynamic nuclear polarization have been proposed as magnetic resonance imaging (MRI) agents for cancer or cardiac failure diagnosis and therapy monitoring through the detection of metabolic impairments in vivo. The use of potentially toxic persistent radicals to hyperpolarize substrates was hitherto required. We demonstrate that by shining UV light for an hour on a frozen pure endogenous substance, namely the glucose metabolic product pyruvic acid, it is possible to generate a concentration of photo-induced radicals that is large enough to highly enhance the 13C polarization of the substance via dynamic nuclear polarization. These radicals recombine upon dissolution and a solution composed of purely endogenous products is obtained for performing in vivo metabolic hyperpolarized 13C MRI with high spatial resolution. Our method opens the way to safe and straightforward preclinical and clinical applications of hyperpolarized MRI because the filtering procedure mandatory for clinical applications and the associated pharmacological tests necessary to prevent contamination are eliminated, concurrently allowing a decrease in the delay between preparation and injection of the imaging agents for improved in vivo sensitivity. PMID:24145405

An atypical case of SCN9A mutation presenting with global motor delay and a severe pain disorder.

PubMed

Meijer, Inge Anita; Vanasse, Michel; Nizard, Sonia; Robitaille, Yves; Rossignol, Elsa

2014-01-01

Erythromelalgia due to heterozygous gain-of-function SCN9A mutations usually presents as a pure sensory-autonomic disorder characterized by recurrent episodes of burning pain and redness of the extremities. We describe a patient with an unusual phenotypic presentation of gross motor delay, childhood-onset erythromelalgia, extreme visceral pain episodes, hypesthesia, and self-mutilation. The investigation of the patient's motor delay included various biochemical analyses, a comparative genomic hybridization array (CGH), electromyogram (EMG), and muscle biopsy. Once erythromelalgia was suspected clinically, the SCN9A gene was sequenced. The EMG, CGH, and biochemical tests were negative. The biopsy showed an axonal neuropathy and neurogenic atrophy. Sequencing of SCN9A revealed a heterozygous missense mutation in exon 7; p.I234T. This is a case of global motor delay and erythromelalgia associated with SCN9A. The motor delay may be attributed to the extreme pain episodes or to a developmental perturbation of proprioceptive inputs. Copyright © 2013 Wiley Periodicals, Inc.

Links between ammonia oxidizer species composition, functional diversity and nitrification kinetics in grassland soils.

PubMed

Webster, Gordon; Embley, T Martin; Freitag, Thomas E; Smith, Zena; Prosser, James I

2005-05-01

Molecular approaches have revealed considerable diversity and uncultured novelty in natural prokaryotic populations, but not direct links between the new genotypes detected and ecosystem processes. Here we describe the influence of the structure of communities of ammonia-oxidizing bacteria on nitrogen cycling in microcosms containing natural and managed grasslands and amended with artificial sheep urine, a major factor determining local ammonia concentrations in these environments. Nitrification kinetics were assessed by analysis of changes in urea, ammonia, nitrite and nitrate concentrations and ammonia oxidizer communities were characterized by analysis of 16S rRNA genes amplified from extracted DNA using ammonia oxidizer-specific primers. In natural soils, ammonia oxidizer community structure determined the delay preceding nitrification, which depended on the relative abundance of two Nitrosospira clusters, termed 3a and 3b. In batch cultures, pure culture and enrichment culture representatives of Nitrosospira 3a were sensitive to high ammonia concentration, while Nitrosospira cluster 3b representatives and Nitrosomonas europaea were tolerant. Delays in nitrification occurred in natural soils dominated by Nitrosospira cluster 3a and resulted from the time required for growth of low concentrations of Nitrosospira cluster 3b. In microcosms dominated by Nitrosospira cluster 3b and Nitrosomonas, no substantial delays were observed. In managed soils, no delays in nitrification were detected, regardless of initial ammonia oxidizer community structure, most probably resulting from higher ammonia oxidizer cell concentrations. The data therefore demonstrate a direct link between bacterial community structure, physiological diversity and ecosystem function.

Effect of V-Nd co-doping on phase transformation and grain growth process of TiO2

NASA Astrophysics Data System (ADS)

Khatun, Nasima; Amin, Ruhul; Anita, Sen, Somaditya

2018-05-01

The pure and V-Nd co-doped TiO2 samples are prepared by the modified sol-gel process. The phase formation is confirmed by XRD spectrum. Phase transformation is delayed in V-Nd co-doped TiO2 (TVN) samples compared to pure TiO2. The particle size is comparatively small in TVN samples at both the temperature 450 °C and 900 °C. Hence the effect of Nd doping is dominated over V doping in both phase transformation and grain growth process of TiO2.

A real-time biomimetic acoustic localizing system using time-shared architecture

NASA Astrophysics Data System (ADS)

Nourzad Karl, Marianne; Karl, Christian; Hubbard, Allyn

2008-04-01

In this paper a real-time sound source localizing system is proposed, which is based on previously developed mammalian auditory models. Traditionally, following the models, which use interaural time delay (ITD) estimates, the amount of parallel computations needed by a system to achieve real-time sound source localization is a limiting factor and a design challenge for hardware implementations. Therefore a new approach using a time-shared architecture implementation is introduced. The proposed architecture is a purely sample-base-driven digital system, and it follows closely the continuous-time approach described in the models. Rather than having dedicated hardware on a per frequency channel basis, a specialized core channel, shared for all frequency bands is used. Having an optimized execution time, which is much less than the system's sample rate, the proposed time-shared solution allows the same number of virtual channels to be processed as the dedicated channels in the traditional approach. Hence, the time-shared approach achieves a highly economical and flexible implementation using minimal silicon area. These aspects are particularly important in efficient hardware implementation of a real time biomimetic sound source localization system.

Passive wireless surface acoustic wave sensors for monitoring sequestration sites CO 2 emission

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yizhong; Chyu, Minking; Wang, Qing-Ming

2013-02-14

University of Pittsburgh’s Transducer lab has teamed with the U.S. Department of Energy’s National Energy Technology Laboratory (DOE NETL) to conduct a comprehensive study to develop/evaluate low-cost, efficient CO 2 measuring technologies for geological sequestration sites leakage monitoring. A passive wireless CO 2 sensing system based on surface acoustic wave technology and carbon nanotube nanocomposite was developed. Surface acoustic wave device was studied to determine the optimum parameters. Delay line structure was adopted as basic sensor structure. CNT polymer nanocomposite was fabricated and tested under different temperature and strain condition for natural environment impact evaluation. Nanocomposite resistance increased for 5more » times under pure strain, while the temperature dependence of resistance for CNT solely was -1375ppm/°C. The overall effect of temperature on nanocomposite resistance was -1000ppm/°C. The gas response of the nanocomposite was about 10% resistance increase under pure CO 2 . The sensor frequency change was around 300ppm for pure CO 2 . With paralyne packaging, the sensor frequency change from relative humidity of 0% to 100% at room temperature decreased from over 1000ppm to less than 100ppm. The lowest detection limit of the sensor is 1% gas concentration, with 36ppm frequency change. Wireless module was tested and showed over one foot transmission distance at preferred parallel orientation.« less

Detectability of Granger causality for subsampled continuous-time neurophysiological processes.

PubMed

Barnett, Lionel; Seth, Anil K

2017-01-01

Granger causality is well established within the neurosciences for inference of directed functional connectivity from neurophysiological data. These data usually consist of time series which subsample a continuous-time biophysiological process. While it is well known that subsampling can lead to imputation of spurious causal connections where none exist, less is known about the effects of subsampling on the ability to reliably detect causal connections which do exist. We present a theoretical analysis of the effects of subsampling on Granger-causal inference. Neurophysiological processes typically feature signal propagation delays on multiple time scales; accordingly, we base our analysis on a distributed-lag, continuous-time stochastic model, and consider Granger causality in continuous time at finite prediction horizons. Via exact analytical solutions, we identify relationships among sampling frequency, underlying causal time scales and detectability of causalities. We reveal complex interactions between the time scale(s) of neural signal propagation and sampling frequency. We demonstrate that detectability decays exponentially as the sample time interval increases beyond causal delay times, identify detectability "black spots" and "sweet spots", and show that downsampling may potentially improve detectability. We also demonstrate that the invariance of Granger causality under causal, invertible filtering fails at finite prediction horizons, with particular implications for inference of Granger causality from fMRI data. Our analysis emphasises that sampling rates for causal analysis of neurophysiological time series should be informed by domain-specific time scales, and that state-space modelling should be preferred to purely autoregressive modelling. On the basis of a very general model that captures the structure of neurophysiological processes, we are able to help identify confounds, and offer practical insights, for successful detection of causal connectivity from neurophysiological recordings. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhanced effect of geldanamycin nanocomposite against breast cancer cells growing in vitro and as xenograft with vanquished normal cell toxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhu, Suma

Despite enormous advances in remedies developed for breast cancer, an effective therapeutic strategy by targeting malignant cells with the least normal tissue toxicity is yet to be developed. Hsp90 is considered to be an important therapeutic target to inhibit cell proliferation. Geldanamycin (GDM), a potent inhibitor of Hsp90 was withdrawn from clinical trials due to its undesirable hepatotoxicity. We report a superparamagnetic iron oxide (SPION) based polymeric nanocomposite of GDM augmenting anticancer competence with decreased hepatic toxicity. The particle size of nanocomposite was ascertained to be 76 ± 10 nm with acceptable stability. A comparative dose dependent in vitro validationmore » of cytotoxicity showed an enhanced cellular damage and necrosis in breast cancer (MCF-7) cell line at a low dose of 5.49 nM (in GDM nanocomposite) in contrast to 20 nM of pure GDM, while normal breast epithelial cells (MCF-10A) were least affected. Besides, in vivo study (in breast cancer xenografts) substantiated 2.7 fold delay in tumor progression mediated by redundancy in the downstream functions of p-Akt and MAPK-Erk leading to apoptosis with negligible hepatotoxicity. Pure GDM disrupted the function and morphology of liver with lesser therapeutic efficacy than the GDM nanocomposite. These findings deduce that GDM based polymeric magnetite nanocomposite play a vital role in efficacious therapy while vanquishing normal cells and hepatic toxicity and thereby promising it to be reinstated in clinics. - Highlights: • GDM nanocomposite shows selective cell kill of cancerous breast cells. • Nanocomposite delays the growth of tumor in comparison to pure GDM treatment. • GDM promotes apoptosis by down-regulation of p-Akt and MAPK-Erk. • GDM nanocomposite nullifies the hepatotoxicity generally exhibited by pure GDM.« less

Pure-phase selective excitation in fast-relaxing systems.

PubMed

Zangger, K; Oberer, M; Sterk, H

2001-09-01

Selective pulses have been used frequently for small molecules. However, their application to proteins and other macromolecules has been limited. The long duration of shaped-selective pulses and the short T(2) relaxation times in proteins often prohibited the use of highly selective pulses especially on larger biomolecules. A very selective excitation can be obtained within a short time by using the selective excitation sequence presented in this paper. Instead of using a shaped low-intensity radiofrequency pulse, a cluster of hard 90 degrees pulses, delays of free precession, and pulsed field gradients can be used to selectively excite a narrow chemical shift range within a relatively short time. Thereby, off-resonance magnetization, which is allowed to evolve freely during the free precession intervals, is destroyed by the gradient pulses. Off-resonance excitation artifacts can be removed by random variation of the interpulse delays. This leads to an excitation profile with selectivity as well as phase and relaxation behavior superior to that of commonly used shaped-selective pulses. Since the evolution of scalar coupling is inherently suppressed during the double-selective excitation of two different scalar-coupled nuclei, the presented pulse cluster is especially suited for simultaneous highly selective excitation of N-H and C-H fragments. Experimental examples are demonstrated on hen egg white lysozyme (14 kD) and the bacterial antidote ParD (19 kD). Copyright 2001 Academic Press.

Under-the-barrier dynamics in laser-induced relativistic tunneling.

PubMed

Klaiber, Michael; Yakaboylu, Enderalp; Bauke, Heiko; Hatsagortsyan, Karen Z; Keitel, Christoph H

2013-04-12

The tunneling dynamics in relativistic strong-field ionization is investigated with the aim to develop an intuitive picture for the relativistic tunneling regime. We demonstrate that the tunneling picture applies also in the relativistic regime by introducing position dependent energy levels. The quantum dynamics in the classically forbidden region features two time scales, the typical time that characterizes the probability density's decay of the ionizing electron under the barrier (Keldysh time) and the time interval which the electron spends inside the barrier (Eisenbud-Wigner-Smith tunneling time). In the relativistic regime, an electron momentum shift as well as a spatial shift along the laser propagation direction arise during the under-the-barrier motion which are caused by the laser magnetic field induced Lorentz force. The momentum shift is proportional to the Keldysh time, while the wave-packet's spatial drift is proportional to the Eisenbud-Wigner-Smith time. The signature of the momentum shift is shown to be present in the ionization spectrum at the detector and, therefore, observable experimentally. In contrast, the signature of the Eisenbud-Wigner-Smith time delay disappears at far distances for pure quasistatic tunneling dynamics.

Who do you love, your mother or your horse? An event-related brain potential analysis of tone processing in Mandarin Chinese.

PubMed

Brown-Schmidt, Sarah; Canseco-Gonzalez, Enriqueta

2004-03-01

In Mandarin Chinese, word meaning is partially determined by lexical tone (Wang, 1973). Previous studies suggest that lexical tone is processed as linguistic information and not as pure tonal information (Gandour, 1998; Van Lanker & Fromkin, 1973). The current study explored the online processing of lexical tones. Event-related potentials were obtained from 25 Mandarin speakers while they listened to normal and anomalous sentences containing one of three types of semantic anomalies created by manipulating the tone, the syllable, or both tone and syllable (double-anomaly) of sentence-final words. We hypothesized N400 effects elicited by all three types of anomalies and the largest by the double-anomaly. As expected, all three elicited N400 effects starting approximately 150 ms poststimulus and continuing until 1000 ms in some areas. Surprisingly, onset of the double-anomaly effect was approximately 50 ms later than the rest. Delayed detection of errors in this condition may be responsible for the apparent delay. Slight differences between syllable and tone conditions may be due to the relative timing of these acoustic cues.

Effect of silane concentration on the supersonic combustion of a silane/methane mixture

NASA Technical Reports Server (NTRS)

Northam, G. B.; Mclain, A. G.; Pellett, G. L.; Diskin, G. S.

1986-01-01

A series of direct connect combustor tests was conducted to determine the effect of silane concentration on the supersonic combustion characteristics of silane/methane mixtures. Shock tube ignition delay data indicated more than an order of magnitude reduction in ignition delay times for both 10 and 20 percent silane/methane mixtures as compared to methane. The ignition delay time of the 10 percent mixture was only a factor of 2.3 greater than that of the 20 percent mixture. Supersonic combustion tests were conducted with the fuel injected into a model scramjet combustor. The combustor was mounted at the exit of a Mach 2 nozzle and a hydrogen fired heater was used to provide a variation in test gas total temperature. Tests using the 20 percent silane/methane mixture indicated considerable combustion enhancement when compared to methane alone. This mixture had an autoignition total temperature of 1650 R. This autoignition temperature can be contrasted with 2330 R for hydrogen and 1350 R for a 20 percent silane/hydrogen mixture in similar hardware. Methane without the silane additive did not autoignite in this configuration at total temperatures as high as 3900 R, the maximum temperature at which tests were conducted. Supersonic combustion tests with the silane concentration reduced to 10 percent indicated little improvement in combustion performance over pure methane. The addition of 20 percent silane to methane resulted in a pyrophoric fuel with good supersonic combustion performance. Reducing the silane concentration below this level, however, yielded a less pyrophoric fuel that exhibited poor supersonic combustion performance.

Boon and Bane of Inflammation in Bone Tissue Regeneration and Its Link with Angiogenesis.

PubMed

Schmidt-Bleek, Katharina; Kwee, Brian J; Mooney, David J; Duda, Georg N

2015-08-01

Delayed healing or nonhealing of bone is an important clinical concern. Although bone, one of the two tissues with scar-free healing capacity, heals in most cases, healing is delayed in more than 10% of clinical cases. Treatment of such delayed healing condition is often painful, risky, time consuming, and expensive. Tissue healing is a multistage regenerative process involving complex and well-orchestrated steps, which are initiated in response to injury. At best, these steps lead to scar-free tissue formation. At the onset of healing, during the inflammatory phase, stationary and attracted macrophages and other immune cells at the fracture site release cytokines in response to injury. This initial reaction to injury is followed by the recruitment, proliferation, and differentiation of mesenchymal stromal cells, synthesis of extracellular matrix proteins, angiogenesis, and finally tissue remodeling. Failure to heal is often associated with poor revascularization. Since blood vessels mediate the transport of circulating cells, oxygen, nutrients, and waste products, they appear essential for successful healing. The strategy of endogenous regeneration in a tissue such as bone is interesting to analyze since it may represent a blueprint of successful tissue formation. This review highlights the interdependency of the time cascades of inflammation, angiogenesis, and tissue regeneration. A better understanding of these inter-relations is mandatory to early identify patients at risk as well as to overcome critical clinical conditions that limit healing. Instead of purely tolerating the inflammatory phase, modulations of inflammation (immunomodulation) might represent a valid therapeutic strategy to enhance angiogenesis and foster later phases of tissue regeneration.

Sleep-dependent consolidation benefits fast transfer of time interval training.

PubMed

Chen, Lihan; Guo, Lu; Bao, Ming

2017-03-01

Previous study has shown that short training (15 min) for explicitly discriminating temporal intervals between two paired auditory beeps, or between two paired tactile taps, can significantly improve observers' ability to classify the perceptual states of visual Ternus apparent motion while the training of task-irrelevant sensory properties did not help to improve visual timing (Chen and Zhou in Exp Brain Res 232(6):1855-1864, 2014). The present study examined the role of 'consolidation' after training of temporal task-irrelevant properties, or whether a pure delay (i.e., blank consolidation) following pretest of the target task would give rise to improved ability of visual interval timing, typified in visual Ternus display. A procedure of pretest-training-posttest was adopted, with the probe of discriminating Ternus apparent motion. The extended implicit training of timing in which the time intervals between paired auditory beeps or paired tactile taps were manipulated but the task was discrimination of the auditory pitches or tactile intensities, did not lead to the training benefits (Exps 1 and 3); however, a delay of 24 h after implicit training of timing, including solving 'Sudoku puzzles,' made the otherwise absent training benefits observable (Exps 2, 4, 5 and 6). The above improvements in performance were not due to a practice effect of Ternus motion (Exp 7). A general 'blank' consolidation period of 24 h also made improvements of visual timing observable (Exp 8). Taken together, the current findings indicated that sleep-dependent consolidation imposed a general effect, by potentially triggering and maintaining neuroplastic changes in the intrinsic (timing) network to enhance the ability of time perception.

On the Relationship Between Scintillation Anisotropy and Crystal Structure in Pure Crystalline Organic Scintillator Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schuster, Patricia; Feng, Patrick; Brubaker, Erik

We report the scintillation anisotropy effect for proton recoil events has been investigated in five pure organic crystalline materials: anthracene, trans-stilbene, p-terphenyl, bibenzyl, and diphenylacetylene. These measurements include characterization of the scintillation response for one hemisphere of proton recoil directions in each crystal. In addition to standard measurements of the total light output and pulse shape at each angle, the prompt and delayed light anisotropies are analyzed, allowing for investigation of the singlet and triplet molecular excitation behaviors independently. This work provides new quantitative and qualitative observations that make progress toward understanding the physical mechanisms behind the scintillation anisotropy. Thesemore » measurements show that the relationship between the prompt and delayed light anisotropies is correlated with crystal structure, as it changes between the pi-stacked crystal structure materials (anthracene and p-terphenyl) and the herringbone crystal structure materials (stilbene, bibenzyl, and diphenylacetylene). The observations are consistent with a model in which there are preferred directions of kinetic processes for the molecular excitations. Finally, these processes and the impact of their directional dependencies on the scintillation anisotropy are discussed.« less

On the Relationship Between Scintillation Anisotropy and Crystal Structure in Pure Crystalline Organic Scintillator Materials

DOE PAGES

Schuster, Patricia; Feng, Patrick; Brubaker, Erik

2018-05-03

We report the scintillation anisotropy effect for proton recoil events has been investigated in five pure organic crystalline materials: anthracene, trans-stilbene, p-terphenyl, bibenzyl, and diphenylacetylene. These measurements include characterization of the scintillation response for one hemisphere of proton recoil directions in each crystal. In addition to standard measurements of the total light output and pulse shape at each angle, the prompt and delayed light anisotropies are analyzed, allowing for investigation of the singlet and triplet molecular excitation behaviors independently. This work provides new quantitative and qualitative observations that make progress toward understanding the physical mechanisms behind the scintillation anisotropy. Thesemore » measurements show that the relationship between the prompt and delayed light anisotropies is correlated with crystal structure, as it changes between the pi-stacked crystal structure materials (anthracene and p-terphenyl) and the herringbone crystal structure materials (stilbene, bibenzyl, and diphenylacetylene). The observations are consistent with a model in which there are preferred directions of kinetic processes for the molecular excitations. Finally, these processes and the impact of their directional dependencies on the scintillation anisotropy are discussed.« less

Determinants of perception of heartburn and regurgitation

PubMed Central

Bredenoord, A J; Weusten, B L A M; Curvers, W L; Timmer, R; Smout, A J P M

2006-01-01

Background and aim It is not known why some reflux episodes evoke symptoms and others do not. We investigated the determinants of perception of gastro‐oesophageal reflux. Methods In 32 patients with symptoms suggestive of gastro‐oesophageal reflux, 24 hour ambulatory pH and impedance monitoring was performed after cessation of acid suppressive therapy. In the 20 patients who had at least one symptomatic reflux episode, characteristics of symptomatic and asymptomatic reflux episodes were compared. Results A total of 1807 reflux episodes were detected, 203 of which were symptomatic. Compared with asymptomatic episodes, symptomatic episodes were associated with a larger pH drop (p<0.001), lower nadir pH (p<0.05), and higher proximal extent (p<0.005). Symptomatic reflux episodes had a longer volume and acid clearance time (p<0.05 and p<0.002). Symptomatic episodes were preceded by a higher oesophageal cumulative acid exposure time (p<0.05). The proximal extent of episodes preceding regurgitation was larger than those preceding heartburn; 14.8% of the symptomatic reflux episodes were weakly acidic. In total, 426 pure gas reflux episodes occurred, of which 12 were symptomatic. Symptomatic pure gas reflux was more frequently accompanied by a pH drop than asymptomatic gas reflux (p<0.05). Conclusions Heartburn and regurgitation are more likely to be evoked when the pH drop is large, proximal extent of the refluxate is high, and volume and acid clearance is delayed. Sensitisation of the oesophagus occurs by preceding acid exposure. Weakly acidic reflux is responsible for only a minority of symptoms in patients off therapy. Pure gas reflux associated with a pH drop (“acid vapour”) can be perceived as heartburn and regurgitation. PMID:16120760

Strategic retrieval processing and the impact of knowing when a memory was first created.

PubMed

Roberts, J S; Tsivilis, D; Mayes, A R

2014-04-01

Retrieval orientation refers to a process where participants strategically alter how a memory cue is processed in response to different task demands. In the present study we explored whether retrieval orientation is influenced by knowing when an old stimulus was first encoded. Participants completed separate remember/know test blocks for old items from a recent delay (40min) and old items from a remote delay (48h). Manipulations at encoding ensured that performance levels were matched between these two blocks, thus avoiding confounds with differences in retrieval effort. Importantly, a third test block comprised old items from both delays randomly intermixed. As the nature of the old items varies unpredictably in the mixed block, it should not be possibly to adopt a specific retrieval orientation and the mixed block therefore acts as a control condition. Participants saw the words "mixed," "recent" or "remote" prior to each test block. Comparing ERPs from the recent and remote blocks permitted an investigation of whether participants alter their retrieval orientation in response to the specific length of the retention interval. Comparing ERPs from the pure (recent and remote) test blocks to ERPs from the mixed block permitted an investigation of whether delay information per se led to differences in retrieval strategy. Analysis of the ERP data found no differences between the recent and remote blocks. However, ERPs from these pure blocks were significantly less positive than ERPs from the mixed block from 200ms towards the end of the epoch. The findings suggest that the delay information was useful in a general sense and encouraged retrieval strategies distinct from those engaged in the mixed block. We speculate that such strategies might relate to whether or not the retrieval search is specific and constrained and/or whether processes that serve to reinstate the original encoding context are engaged. Copyright © 2014 Elsevier Inc. All rights reserved.

Response of two-phase droplets to intense electromagnetic radiation

NASA Technical Reports Server (NTRS)

Spann, James F.; Maloney, Daniel J.; Lawson, William F.; Casleton, Kent H.

1993-01-01

The response of two-phase droplets to intense radiant heating is studied to determine the incident power that is required for causing explosive boiling in the liquid phase. The droplets studied consist of strongly absorbing coal particles dispersed in a weakly absorbing water medium. Experiments are performed by confining droplets (radii of 37, 55, and 80 microns) electrodynamically and irradiating them from two sides with pulsed laser beams. Emphasis is placed on the transition region from accelerated droplet vaporization to droplet superheating and explosive boiling. The time scale observed for explosive boiling is more than 2 orders of magnitude longer than published values for pure liquids. The delayed response is the result of energy transfer limitations between the absorbing solid phase and the surrounding liquid.

Thermal modelling and control of 130kw direct contact (salt/air) heat exchanger

NASA Astrophysics Data System (ADS)

Qureshi, Omer A.; Calvet, Nicolas; Armstrong, Peter R.

2017-06-01

This work investigates the transient response of a certain type of direct contact heat exchanger (DCHX) that consists of packing (Raschig Rings) to increase the surface area for effective heat transfer between molten salt and air. Molten salt from the hot tank enters the heat exchanger (HX) and exit after heating the air still in the molten form. Thermal capacitance of the HX, mainly due to packing and resident salt inside the HX, results in strong transient response. Pure delay from salt residence time may also impact transient response. Both phenomena have been modelled in this paper. A Proportional-Integral controller (PI control) performance has been evaluated to maintain the minimum salt temperature above avoid crystallization temperature of the salt.

[Conversion of sound into auditory nerve action potentials].

PubMed

Encke, J; Kreh, J; Völk, F; Hemmert, W

2016-11-01

Outer hair cells play a major role in the hearing process: they amplify the motion of the basilar membrane up to a 1000-fold and at the same time sharpen the excitation patterns. These patterns are converted by inner hair cells into action potentials of the auditory nerve. Outer hair cells are delicate structures and easily damaged, e. g., by overexposure to noise. Hearing aids can amplify the amplitude of the excitation patterns, but they cannot restore their degraded frequency selectivity. Noise overexposure also leads to delayed degeneration of auditory nerve fibers, particularly those with low a spontaneous rate, which are important for the coding of sound in noise. However, this loss cannot be diagnosed by pure-tone audiometry.

A novel, optical, on-line bacteria sensor for monitoring drinking water quality

PubMed Central

Højris, Bo; Christensen, Sarah Christine Boesgaard; Albrechtsen, Hans-Jørgen; Smith, Christian; Dahlqvist, Mathis

2016-01-01

Today, microbial drinking water quality is monitored through either time-consuming laboratory methods or indirect on-line measurements. Results are thus either delayed or insufficient to support proactive action. A novel, optical, on-line bacteria sensor with a 10-minute time resolution has been developed. The sensor is based on 3D image recognition, and the obtained pictures are analyzed with algorithms considering 59 quantified image parameters. The sensor counts individual suspended particles and classifies them as either bacteria or abiotic particles. The technology is capable of distinguishing and quantifying bacteria and particles in pure and mixed suspensions, and the quantification correlates with total bacterial counts. Several field applications have demonstrated that the technology can monitor changes in the concentration of bacteria, and is thus well suited for rapid detection of critical conditions such as pollution events in drinking water. PMID:27040142

A novel, optical, on-line bacteria sensor for monitoring drinking water quality.

PubMed

Højris, Bo; Christensen, Sarah Christine Boesgaard; Albrechtsen, Hans-Jørgen; Smith, Christian; Dahlqvist, Mathis

2016-04-04

Today, microbial drinking water quality is monitored through either time-consuming laboratory methods or indirect on-line measurements. Results are thus either delayed or insufficient to support proactive action. A novel, optical, on-line bacteria sensor with a 10-minute time resolution has been developed. The sensor is based on 3D image recognition, and the obtained pictures are analyzed with algorithms considering 59 quantified image parameters. The sensor counts individual suspended particles and classifies them as either bacteria or abiotic particles. The technology is capable of distinguishing and quantifying bacteria and particles in pure and mixed suspensions, and the quantification correlates with total bacterial counts. Several field applications have demonstrated that the technology can monitor changes in the concentration of bacteria, and is thus well suited for rapid detection of critical conditions such as pollution events in drinking water.

Operating characteristics of a hydrogen-argon plasma torch for supersonic combustion applications

NASA Technical Reports Server (NTRS)

Barbi, E.; Mahan, J. R.; O'Brien, W. F.; Wagner, T. C.

1989-01-01

The residence time of the combustible mixture in the combustion chamber of a scramjet engine is much less than the time normally required for complete combustion. Hydrogen and hydrocarbon fuels require an ignition source under conditions typically found in a scramjet combustor. Analytical studies indicate that the presence of hydrogen atoms should greatly reduce the ignition delay in this environment. Because hydrogen plasmas are prolific sources of hydrogen atoms, a low-power, uncooled hydrogen plasma torch has been built and tested to evaluate its potential as a possible flame holder for supersonic combustion. The torch was found to be unstable when operated on pure hydrogen; however, stable operation could be obtained by using argon as a body gas and mixing in the desired amount of hydrogen. The stability limits of the torch are delineated and its electrical and thermal behavior documented. An average torch thermal efficiency of around 88 percent is demonstrated.

The synergy between complex channel-specific FIR filter and spatial filter for single-trial EEG classification.

PubMed

Yu, Ke; Wang, Yue; Shen, Kaiquan; Li, Xiaoping

2013-01-01

The common spatial pattern analysis (CSP), a frequently utilized feature extraction method in brain-computer-interface applications, is believed to be time-invariant and sensitive to noises, mainly due to an inherent shortcoming of purely relying on spatial filtering. Therefore, temporal/spectral filtering which can be very effective to counteract the unfavorable influence of noises is usually used as a supplement. This work integrates the CSP spatial filters with complex channel-specific finite impulse response (FIR) filters in a natural and intuitive manner. Each hybrid spatial-FIR filter is of high-order, data-driven and is unique to its corresponding channel. They are derived by introducing multiple time delays and regularization into conventional CSP. The general framework of the method follows that of CSP but performs better, as proven in single-trial classification tasks like event-related potential detection and motor imagery.

Analyzing the relationships between reflection source DPOAEs and SFOAEs using a computational model

NASA Astrophysics Data System (ADS)

Wen, Haiqi; Bowling, Thomas; Meaud, Julien

2018-05-01

Distortion product otoacoustic emissions (DPOAEs) are sounds generated by the cochlea in response to a stimulus that consists of two primary tones. DPOAEs consist of a mixture of emissions arising from two different mechanisms: nonlinear distortion and coherent reflection. Stimulus Frequency Otoacoustic Emissions (SFOAEs) are sounds generated by the cochlea in response to a pure tone; SFOAEs are commonly hypothesized to be generated due to coherent reflection. Nonlinearity of the outer hair cells (OHCs) provides nonlinear amplification to the traveling wave while reflections occur due to pre-existing micromechanical impedance perturbations. In this work, DPOAEs are obtained from a time domain computational model coupling a lumped parameter middle ear model with a multiphysics mechanical-electrical-acoustical model of cochlea. Cochlear roughness is intro-duced by perturbing the value of the OHC electromechanical coupling coefficient to account for the putative inhomogeneities inside the cochlea. The DPOAEs emitted in the ear canal are decomposed into distortion source and reflection source components. The reflection source component of DPOAEs is compared to SFOAEs obtained using a frequency-domain implementation of the model, to help us understand how distortion source and reflection source contributes to total DPOAEs. Moreover, the group delays of reflection sources OAEs are compared to group delays in the basilar membrane velocity to clarify the relationship between basilar membrane and OAE group delays.

Targeting Protein Quality Control Mechanisms by Natural Products to Promote Healthy Ageing.

PubMed

Wedel, Sophia; Manola, Maria; Cavinato, Maria; Trougakos, Ioannis P; Jansen-Dürr, Pidder

2018-05-19

Organismal ageing is associated with increased chance of morbidity or mortality and it is driven by diverse molecular pathways that are affected by both environmental and genetic factors. The progression of ageing correlates with the gradual accumulation of stressors and damaged biomolecules due to the time-dependent decline of stress resistance and functional capacity, which eventually compromise cellular homeodynamics. As protein machines carry out the majority of cellular functions, proteome quality control is critical for cellular functionality and is carried out through the curating activity of the proteostasis network (PN). Key components of the PN are the two main degradation machineries, namely the ubiquitin-proteasome and autophagy-lysosome pathways along with several stress-responsive pathways, such as that of nuclear factor erythroid 2-related factor 2 (Nrf2), which mobilises cytoprotective genomic responses against oxidative and/or xenobiotic damage. Reportedly, genetic or dietary interventions that activate components of the PN delay ageing in evolutionarily diverse organisms. Natural products (extracts or pure compounds) represent an extraordinary inventory of highly diverse structural scaffolds that offer promising activities towards meeting the challenge of increasing healthspan and/or delaying ageing (e.g., spermidine, quercetin or sulforaphane). Herein, we review those natural compounds that have been found to activate proteostatic and/or anti-stress cellular responses and hence have the potential to delay cellular senescence and/or in vivo ageing.

The Role of Convection and Growth Competition in Phase Selection in Microgravity: Controlled Convection in the Containerless Processing of Steel Alloys

NASA Technical Reports Server (NTRS)

Matson, D. M.; Loser, W.; Rogers, J. R.; Flemings, M. C.

2001-01-01

Containerless processing using electromagnetic levitation (EML) is a powerful technique in the investigation of reactive molten metal systems. On ground, the power required to overcome the weight of the sample is sufficient to cause significant heating and induce substantial melt convection. In microgravity, the heating and positioning fields may be decoupled and the field strength may be varied to achieve the desired level of convection within the limits set by the geometry of the levitation coil and the sample size. From high-speed digital images of the double recalescence behavior of Fe-Cr-Ni alloys in ground-based testing and in reduced-gravity aboard the NASA KC-135 parabolic aircraft, we have shown that phase selection can be predicted based on a growth competition model. An important parameter in this model is the delay time between primary nucleation and subsequent nucleation of the stable solid within the liquid/metastable solid array. This delay time is a strong function of composition and a weak function of the undercooling of the melt below the metastable liquidus. From the results obtained during the first Microgravity Sciences Laboratory (MSL-1) mission, we also know that convection may significantly influence the delay time, especially at low undercoolings. Currently, it is unclear what mechanism controls the formation of a heterogeneous site that allows nucleation of the austenitic phase on the pre-existing ferrite skeleton. By examining the behavior of the delay time under different convective conditions, we hypothesize that we can differentiate between several of these mechanisms to gain an understanding of how to control microstructural. evolution. We will anchor these predictions by examining samples quenched at different times following primary recalescence in microgravity. A second important parameter in the growth competition model is the identification of the growth rate of the stable phase into the semi-solid array that formed during primary recalescence. Current dendritic growth theory is inadequate in predicting solidification behavior under these conditions as metallographic analyses show that stable phase growth proceeds along the interface between the metastable solid and residual liquid. Since growth velocity is independent of the initial undercooling relative to the metastable liquidus, we hypothesize that purely thermal effects can be separated from other important growth model parameters by careful selection of the liquid composition in a ternary system.

Correlates of Chinese Kindergarteners' Word Reading and Writing: The Unique Role of Copying Skills?

ERIC Educational Resources Information Center

Wang, Ying; McBride-Chang, Catherine; Chan, Shing Fong

2014-01-01

Ninety-four Mainland Chinese children in the second and third years of kindergarten (mean age = 65 months, SD = 6.94) were tested on Pinyin letter-name knowledge, invented Pinyin spelling, general copying skills of unfamiliar print (in Korean, Hebrew and Vietnamese, ultimately combined to create a pure copying factor), delayed copying of…

Quantification of deviations from rationality with heavy tails in human dynamics

NASA Astrophysics Data System (ADS)

Maillart, T.; Sornette, D.; Frei, S.; Duebendorfer, T.; Saichev, A.

2011-05-01

The dynamics of technological, economic and social phenomena is controlled by how humans organize their daily tasks in response to both endogenous and exogenous stimulations. Queueing theory is believed to provide a generic answer to account for the often observed power-law distributions of waiting times before a task is fulfilled. However, the general validity of the power law and the nature of other regimes remain unsettled. Using anonymized data collected by Google at the World Wide Web level, we identify the existence of several additional regimes characterizing the time required for a population of Internet users to execute a given task after receiving a message. Depending on the under- or over-utilization of time by the population of users and the strength of their response to perturbations, the pure power law is found to be coextensive with an exponential regime (tasks are performed without too much delay) and with a crossover to an asymptotic plateau (some tasks are never performed).

Performance analysis of the ALOHA protocol with replication in a fading channel for the Mobile Satellite Experiment

NASA Technical Reports Server (NTRS)

Clare, L. P.; Yan, T.-Y.

1985-01-01

The analysis of the ALOHA random access protocol for communications channels with fading is presented. The protocol is modified to send multiple contiguous copies of a message at each transmission attempt. Both pure and slotted ALOHA channels are considered. A general two state model is used for the channel error process to account for the channel fading memory. It is shown that greater throughput and smaller delay may be achieved using repetitions. The model is applied to the analysis of the delay-throughput performance in a fading mobile communications environment. Numerical results are given for NASA's Mobile Satellite Experiment.

Enhancing BEM simulations of a stalled wind turbine using a 3D correction model

NASA Astrophysics Data System (ADS)

Bangga, Galih; Hutomo, Go; Syawitri, Taurista; Kusumadewi, Tri; Oktavia, Winda; Sabila, Ahmad; Setiadi, Herlambang; Faisal, Muhamad; Hendranata, Yongki; Lastomo, Dwi; Putra, Louis; Kristiadi, Stefanus; Bumi, Ilmi

2018-03-01

Nowadays wind turbine rotors are usually employed with pitch control mechanisms to avoid deep stall conditions. Despite that, wind turbines often operate under pitch fault situation causing massive flow separation to occur. Pure Blade Element Momentum (BEM) approaches are not designed for this situation and inaccurate load predictions are already expected. In the present studies, BEM predictions are improved through the inclusion of a stall delay model for a wind turbine rotor operating under pitch fault situation of -2.3° towards stall. The accuracy of the stall delay model is assessed by comparing the results with available Computational Fluid Dynamics (CFD) simulations data.

Delayed Gamma-Ray Spectroscopy for Non-Destructive Assay of Nuclear Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ludewigt, Bernhard; Mozin, Vladimir; Campbell, Luke

2015-06-01

High-­energy, beta-delayed gamma-­ray spectroscopy is a potential, non-­destructive assay techniques for the independent verification of declared quantities of special nuclear materials at key stages of the fuel cycle and for directly assaying nuclear material inventories for spent fuel handling, interim storage, reprocessing facilities, repository sites, and final disposal. Other potential applications include determination of MOX fuel composition, characterization of nuclear waste packages, and challenges in homeland security and arms control verification. Experimental measurements were performed to evaluate fission fragment yields, to test methods for determining isotopic fractions, and to benchmark the modeling code package. Experimental measurement campaigns were carried outmore » at the IAC using a photo-­neutron source and at OSU using a thermal neutron beam from the TRIGA reactor to characterize the emission of high-­energy delayed gamma rays from 235U, 239Pu, and 241Pu targets following neutron induced fission. Data were collected for pure and combined targets for several irradiation/spectroscopy cycle times ranging from 10/10 seconds to 15/30 minutes.The delayed gamma-ray signature of 241Pu, a significant fissile constituent in spent fuel, was measured and compared to 239Pu. The 241Pu/ 239Pu ratios varied between 0.5 and 1.2 for ten prominent lines in the 2700-­3600 keV energy range. Such significant differences in relative peak intensities make it possible to determine relative fractions of these isotopes in a mixed sample. A method for determining fission product yields by fitting the energy and time dependence of the delayed gamma-­ray emission was developed and demonstrated on a limited 235U data set. De-­convolution methods for determining fissile fractions were developed and tested on the experimental data. The use of high count-­rate LaBr 3 detectors was investigated as a potential alternative to HPGe detectors. Modeling capabilities were added to an existing framework and codes were adapted as needed for analyzing experiments and assessing application-­specific assay concepts. A de-­convolution analysis of the delayed gamma-­ray response spectra modeled for spent fuel assemblies was performed using the same method that was applied to the experimental spectra.« less

A light-induced microwave oscillator

NASA Technical Reports Server (NTRS)

Yao, X. S.; Maleki, L.

1995-01-01

We describe a novel oscillator that converts continuous light energy into sta ble and spectrally pure microwave signals. This light-induced microwave oscillator (LIMO) consists of a pump laser and a feedback circuit, including an intensity modulator, an optical fiber delay line, a photodetector, an amplifier, and a filter. We develop a quasilinear theory and obtain expressions for the threshold condition, the amplitude, the frequency, the line width, and the spectral power density of the oscillation. We also present experimental data to compare with the theoretical results. Our findings indicate that the LIMO can generate ultrastable, spectrally pure microwave reference signals up to 75 GHz with a phase noise lower than -140 dBc/Hz at 10 kHz.

Femtosecond time-resolved vibrational SFG spectroscopy of CO/Ru( 0 0 1 )

NASA Astrophysics Data System (ADS)

Hess, Ch.; Wolf, M.; Roke, S.; Bonn, M.

2002-04-01

Vibrational sum-frequency generation (SFG) employing femtosecond infrared (IR) laser pulses is used to study the dynamics of the C-O stretch vibration on Ru(0 0 1). Time-resolved measurements of the free induction decay (FID) of the IR-polarization for 0.33 ML CO/Ru(0 0 1) exhibit single exponential decays over three decades corresponding to dephasing times of T2=1.94 ps at 95 K and T2=1.16 ps at 340 K. This is consistent with pure homogeneous broadening due to anharmonic coupling with the thermally activated low-frequency dephasing mode together with a contribution from saturation of the IR transition. In pump-probe SFG experiments using a strong visible (VIS) pump pulse the perturbation of the FID leads to transient line shifts even at negative delay times, i.e. when the IR-VIS SFG probe pair precedes the pump pulse. Based on an analysis of the time-dependent polarization we discuss the influence of the perturbed FID on time-resolved SFG spectra. We investigate how coherent effects affect the SFG spectra and we examine the time resolution in these experiments, in particular in dependence of the dephasing time.

Gadolinium-enhanced inner ear magnetic resonance imaging for evaluation of delayed endolymphatic hydrops, including a bilateral case.

PubMed

Fukushima, Munehisa; Oya, Ryohei; Akazawa, Hitoshi; Tsuruta, Yukinori; Inohara, Hidenori

2016-01-01

The data suggests that gadolinium-enhanced inner ear MR imaging is useful for diagnosis of delayed endolymphatic hydrops (DEH) because it is independent of inner ear function, and the size of the affected endolymphatic space is clearly enlarged. This study was performed to semi-quantitatively evaluate the endolymphatic space in patients with all types of DEH using gadolinium-enhanced inner ear magnetic resonance (MR) imaging. Seven patients (age range = 21-77 years; five female, two male) with ipsilateral DEH (n = 5), contralateral DEH (n = 1), and bilateral DEH (n = 1). All patients underwent 3T MR imaging 4 h after intravenous injection of gadolinium. Software was used to determine the size of the endolymphatic space. Pure tone audiometry and caloric testing using an electronystagmogram were carried out. One side of the endolymphatic space was dominantly extended in patients with ipsilateral DEH, and both sides of the space were extended in patients with contralateral and bilateral DEH. In patients with ipsilateral DEH, the volume ratio of endolymph to vestibule was 2.5-4.3-times that in the unaffected ear. The volume ratio of endolymph to vestibule was nearly equal in patients with contralateral and bilateral DEH.

Auditory cortex of newborn bats is prewired for echolocation.

PubMed

Kössl, Manfred; Voss, Cornelia; Mora, Emanuel C; Macias, Silvio; Foeller, Elisabeth; Vater, Marianne

2012-04-10

Neuronal computation of object distance from echo delay is an essential task that echolocating bats must master for spatial orientation and the capture of prey. In the dorsal auditory cortex of bats, neurons specifically respond to combinations of short frequency-modulated components of emitted call and delayed echo. These delay-tuned neurons are thought to serve in target range calculation. It is unknown whether neuronal correlates of active space perception are established by experience-dependent plasticity or by innate mechanisms. Here we demonstrate that in the first postnatal week, before onset of echolocation and flight, dorsal auditory cortex already contains functional circuits that calculate distance from the temporal separation of a simulated pulse and echo. This innate cortical implementation of a purely computational processing mechanism for sonar ranging should enhance survival of juvenile bats when they first engage in active echolocation behaviour and flight.

Irrational Delay Revisited: Examining Five Procrastination Scales in a Global Sample

PubMed Central

Svartdal, Frode; Steel, Piers

2017-01-01

Scales attempting to measure procrastination focus on different facets of the phenomenon, yet they share a common understanding of procrastination as an unnecessary, unwanted, and disadvantageous delay. The present paper examines in a global sample (N = 4,169) five different procrastination scales – Decisional Procrastination Scale (DPS), Irrational Procrastination Scale (IPS), Pure Procrastination Scale (PPS), Adult Inventory of Procrastination Scale (AIP), and General Procrastination Scale (GPS), focusing on factor structures and item functioning using Confirmatory Factor Analysis and Item Response Theory. The results indicated that The PPS (12 items selected from DPS, AIP, and GPS) measures different facets of procrastination even better than the three scales it is based on. An even shorter version of the PPS (5 items focusing on irrational delay), corresponds well to the nine-item IPS. Both scales demonstrate good psychometric properties and appear to be superior measures of core procrastination attributes than alternative procrastination scales. PMID:29163302

Irrational Delay Revisited: Examining Five Procrastination Scales in a Global Sample.

PubMed

Svartdal, Frode; Steel, Piers

2017-01-01

Scales attempting to measure procrastination focus on different facets of the phenomenon, yet they share a common understanding of procrastination as an unnecessary, unwanted, and disadvantageous delay. The present paper examines in a global sample ( N = 4,169) five different procrastination scales - Decisional Procrastination Scale (DPS), Irrational Procrastination Scale (IPS), Pure Procrastination Scale (PPS), Adult Inventory of Procrastination Scale (AIP), and General Procrastination Scale (GPS), focusing on factor structures and item functioning using Confirmatory Factor Analysis and Item Response Theory. The results indicated that The PPS (12 items selected from DPS, AIP, and GPS) measures different facets of procrastination even better than the three scales it is based on. An even shorter version of the PPS (5 items focusing on irrational delay), corresponds well to the nine-item IPS. Both scales demonstrate good psychometric properties and appear to be superior measures of core procrastination attributes than alternative procrastination scales.

Feedback and feedforward adaptation to visuomotor delay during reaching and slicing movements.

PubMed

Botzer, Lior; Karniel, Amir

2013-07-01

It has been suggested that the brain and in particular the cerebellum and motor cortex adapt to represent the environment during reaching movements under various visuomotor perturbations. It is well known that significant delay is present in neural conductance and processing; however, the possible representation of delay and adaptation to delayed visual feedback has been largely overlooked. Here we investigated the control of reaching movements in human subjects during an imposed visuomotor delay in a virtual reality environment. In the first experiment, when visual feedback was unexpectedly delayed, the hand movement overshot the end-point target, indicating a vision-based feedback control. Over the ensuing trials, movements gradually adapted and became accurate. When the delay was removed unexpectedly, movements systematically undershot the target, demonstrating that adaptation occurred within the vision-based feedback control mechanism. In a second experiment designed to broaden our understanding of the underlying mechanisms, we revealed similar after-effects for rhythmic reversal (out-and-back) movements. We present a computational model accounting for these results based on two adapted forward models, each tuned for a specific modality delay (proprioception or vision), and a third feedforward controller. The computational model, along with the experimental results, refutes delay representation in a pure forward vision-based predictor and suggests that adaptation occurred in the forward vision-based predictor, and concurrently in the state-based feedforward controller. Understanding how the brain compensates for conductance and processing delays is essential for understanding certain impairments concerning these neural delays as well as for the development of brain-machine interfaces. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Immediate and delayed hyperbaric oxygen therapy as a neuroprotective treatment for traumatic brain injury in mice.

PubMed

Baratz-Goldstein, Renana; Toussia-Cohen, Shlomi; Elpaz, Aviya; Rubovitch, Vardit; Pick, Chaim G

2017-09-01

Traumatic brain injury is the most common cause of death or chronic disability among people under-35-years-old. There is no effective pharmacological treatment currently existing for TBI. Hyperbaric oxygen therapy (HBOT) is defined as the inhalation of pure oxygen in a hyperbaric chamber that is pressurized higher than 1atm. HBOT offers physiological and mechanical effects by inducing a state of increased pressure and hyperoxia. HBOT has been proposed as an effective treatment for moderate traumatic brain injury (mTBI), yet the exact therapeutic window and mechanism that underlies this effect is not completely understood. HBOT was administrated for 4 consecutive days, post a mouse closed head weight drop moderate TBI (mTBI) in 2 different time lines: immediate treatment - initiated 3h post-injury and delayed treatment - initiated 7days post-injury. Behavioral cognitive tests and biochemical changes were assessed. The results were similar for both the immediate and the delayed treatments. mTBI mice exhibited impairment in learning abilities, whereas mTBI mice treated with HBO displayed significant improvement compared with the mTBI group, performing similar to the sham groups. mTBI mice had a decline in myelin basic protein, an increase in neuronal loss (NeuN staining), and an increase in the number of reactive astrocytes (GFAP). The HBO treated mice in both groups did not exhibit these changes and remained similar to the sham group. The delayed HBOT has a potential to serve as a neuroprotective treatment for mTBI with a long therapeutic window. Further research is needed for fully understanding the cellular changes. Copyright © 2017 Elsevier Inc. All rights reserved.

Local Stability of AIDS Epidemic Model Through Treatment and Vertical Transmission with Time Delay

NASA Astrophysics Data System (ADS)

Novi W, Cascarilla; Lestari, Dwi

2016-02-01

This study aims to explain stability of the spread of AIDS through treatment and vertical transmission model. Human with HIV need a time to positively suffer AIDS. The existence of a time, human with HIV until positively suffer AIDS can be delayed for a time so that the model acquired is the model with time delay. The model form is a nonlinear differential equation with time delay, SIPTA (susceptible-infected-pre AIDS-treatment-AIDS). Based on SIPTA model analysis results the disease free equilibrium point and the endemic equilibrium point. The disease free equilibrium point with and without time delay are local asymptotically stable if the basic reproduction number is less than one. The endemic equilibrium point will be local asymptotically stable if the time delay is less than the critical value of delay, unstable if the time delay is more than the critical value of delay, and bifurcation occurs if the time delay is equal to the critical value of delay.

The effects of the framing of time on delay discounting.

PubMed

DeHart, William Brady; Odum, Amy L

2015-01-01

We examined the effects of the framing of time on delay discounting. Delay discounting is the process by which delayed outcomes are devalued as a function of time. Time in a titrating delay discounting task is often framed in calendar units (e.g., as 1 week, 1 month, etc.). When time is framed as a specific date, delayed outcomes are discounted less compared to the calendar format. Other forms of framing time; however, have not been explored. All participants completed a titrating calendar unit delay-discounting task for money. Participants were also assigned to one of two delay discounting tasks: time as dates (e.g., June 1st, 2015) or time in units of days (e.g., 5000 days), using the same delay distribution as the calendar delay-discounting task. Time framed as dates resulted in less discounting compared to the calendar method, whereas time framed as days resulted in greater discounting compared to the calendar method. The hyperboloid model fit best compared to the hyperbola and exponential models. How time is framed may alter how participants attend to the delays as well as how the delayed outcome is valued. Altering how time is framed may serve to improve adherence to goals with delayed outcomes. © Society for the Experimental Analysis of Behavior.

Transport delay compensation for computer-generated imagery systems

NASA Technical Reports Server (NTRS)

Mcfarland, Richard E.

1988-01-01

In the problem of pure transport delay in a low-pass system, a trade-off exists with respect to performance within and beyond a frequency bandwidth. When activity beyond the band is attenuated because of other considerations, this trade-off may be used to improve the performance within the band. Specifically, transport delay in computer-generated imagery systems is reduced to a manageable problem by recognizing frequency limits in vehicle activity and manual-control capacity. Based on these limits, a compensation algorithm has been developed for use in aircraft simulation at NASA Ames Research Center. For direct measurement of transport delays, a beam-splitter experiment is presented that accounts for the complete flight simulation environment. Values determined by this experiment are appropriate for use in the compensation algorithm. The algorithm extends the bandwidth of high-frequency flight simulation to well beyond that of normal pilot inputs. Within this bandwidth, the visual scene presentation manifests negligible gain distortion and phase lag. After a year of utilization, two minor exceptions to universal simulation applicability have been identified and subsequently resolved.

Dynamics of scroll waves with time-delay propagation in excitable media

NASA Astrophysics Data System (ADS)

Chen, Jiang-Xing; Xiao, Jie; Qiao, Li-Yan; Xu, Jiang-Rong

2018-06-01

Information transmission delay can be widely observed in various systems. Here, we study the dynamics of scroll waves with time-delay propagation among slices in excitable media. Weak time delay induces scroll waves to meander. Through increasing the time delay, we find a series of dynamical transitions. Firstly, the straight filament of a scroll wave becomes twisted. Then, the scroll wave breaks and forms interesting patterns. With long time delay, loosed scroll waves are maintained while their period are greatly decreased. Also, cylinder waves appears. The influences of diffusively coupling strength on the time-delay-induced scroll waves are studied. It is found that the critical time delay characterizing those transitions decreases as the coupling strength is increased. A phase diagram in the diffusive coupling-time delay plane is presented.

49 CFR 236.563 - Delay time.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Delay time. 236.563 Section 236.563 Transportation... Cab Signal Systems Rules and Instructions; Locomotives § 236.563 Delay time. Delay time of automatic... requirements of § 236.24 shall take into consideration the delay time. ...

49 CFR 236.563 - Delay time.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 4 2014-10-01 2014-10-01 false Delay time. 236.563 Section 236.563 Transportation... Cab Signal Systems Rules and Instructions; Locomotives § 236.563 Delay time. Delay time of automatic... requirements of § 236.24 shall take into consideration the delay time. ...

First-in-Human PET/CT Imaging of Metastatic Neuroendocrine Neoplasms with Cyclotron-Produced 44Sc-DOTATOC: A Proof-of-Concept Study.

PubMed

Singh, Aviral; van der Meulen, Nicholas P; Müller, Cristina; Klette, Ingo; Kulkarni, Harshad R; Türler, Andreas; Schibli, Roger; Baum, Richard P

2017-05-01

44 Sc is a promising positron emission tomography (PET) radionuclide (T 1/2  = 4.04 hours, E β+average  = 632 keV) and can be made available, using a cyclotron production route, in substantial quantities as a highly pure product. Herein, the authors report on a first-in-human PET/CT study using 44 Sc-DOTATOC prepared with cyclotron-produced 44 Sc. The production of 44 Sc was carried out through the 44 Ca(p,n) 44 Sc nuclear reaction at Paul Scherrer Institut, Switzerland. After separation, 44 Sc was shipped to Zentralklinik Bad Berka, Germany, where radiolabeling was performed, yielding radiochemically pure 44 Sc-DOTATOC. Two patients, currently followed up after peptide receptor radionuclide therapy of metastatic neuroendocrine neoplasms, participated in this proof-of-concept study. Blood sampling was performed before and after application of 44 Sc-DOTATOC. PET/CT acquisitions, performed at different time points after injection of 44 Sc-DOTATOC, allowed detection of even very small lesions on delayed scans. No clinical adverse effects were observed and the laboratory hematological, renal, and hepatic profiles remained unchanged. In this study, cyclotron-produced 44 Sc was used in the clinic for the first time. It is attractive for theranostic application with 177 Lu, 90 Y, or 47 Sc as therapeutic counterparts. 44 Sc-based radiopharmaceuticals will be of particular value for PET facilities without radiopharmacy, to which they can be shipped from a centralized production site.

Aluminum Shear Panels for Seismic Protection of Framed Structures: Review of Recent Experimental Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Matteis, G.; Brando, G.; Panico, S.

An important experimental campaign on pure aluminum shear panels, to develop new devices for the seismic passive protection of buildings, has been recently carried out at the University of Naples 'Federico II' in cooperation with the University 'G. d'Annunzio' of Chieti/Pescara. In particular, several pure aluminum shear panels, suitably reinforced by ribs in order to delay shear buckling in the plastic deformation field, have been tested under cyclic loads. The choice pure aluminium, which is really innovative in the field of civil engineering, is justified by both the nominal low yield strength and the high ductility of such a material,more » which have been further improved through a proper heat treatment. Two different testing layouts have been adopted. In the former, six 'full bay' pure aluminum shear panels, having in-plane dimensions 1500x1000 mm and thickness of 5 mm, have been taken in consideration. In the latter, four 5 mm thick stiffened bracing type pure aluminum shear panels (BTPASPs) with a square shape of 500 mm side length have been cyclically tested under diagonal load. In the whole several plate slenderness ratios have been considered, allowing the evaluation of the most influential factors on the cyclic performance of system. In the current paper a review of the most important results of these recent experimental activities is provided and discussed.« less

Wigner time delay in photodetachment of Tm-and in photoionization of Yb: A comparative study

NASA Astrophysics Data System (ADS)

Saha, Soumyajit; Jose, Jobin; Deshmukh, Pranawa; Dolmatov, Valeriy; Kheifets, Anatoli; Manson, Steven

2017-04-01

Preliminary studies of Wigner time delay in photodetachment spectra of negative ions have been reported. Photodetachment time delay for some dipole channels of Tm- and of Cl- were calculated using relativistic random phase approximation (RRPA). Comparisons between photodetachment time delay of Cl- and photoionization time delay of Ar were made. We investigate the photodetachment time delay for all three relativistically split nd -> ɛ f channels of Tm- and for nd -> ɛ f channels of Yb (isoelectronic to Tm-) using RRPA. We study the effect of the shape resonance, brought about by the centrifugal barrier potential, on photodetachment time delay. A negative ion is a good laboratory for studying the effects of shape resonances on time delay since the phase is unaffected by the Coulomb component. Wigner time delay in photodetachment of Tm- and in photoionization of Yb: A comparative study.

Effects of partial time delays on phase synchronization in Watts-Strogatz small-world neuronal networks.

PubMed

Sun, Xiaojuan; Perc, Matjaž; Kurths, Jürgen

2017-05-01

In this paper, we study effects of partial time delays on phase synchronization in Watts-Strogatz small-world neuronal networks. Our focus is on the impact of two parameters, namely the time delay τ and the probability of partial time delay p delay , whereby the latter determines the probability with which a connection between two neurons is delayed. Our research reveals that partial time delays significantly affect phase synchronization in this system. In particular, partial time delays can either enhance or decrease phase synchronization and induce synchronization transitions with changes in the mean firing rate of neurons, as well as induce switching between synchronized neurons with period-1 firing to synchronized neurons with period-2 firing. Moreover, in comparison to a neuronal network where all connections are delayed, we show that small partial time delay probabilities have especially different influences on phase synchronization of neuronal networks.

Cherenkov and scintillation light separation on the CheSS experiment

NASA Astrophysics Data System (ADS)

Caravaca, Javier; Land, Benjamin; Descamps, Freija; Orebi Gann, Gabriel D.

2016-09-01

Separation of the scintillation and Cherenkov light produced in liquid scintillators enables outstanding capabilities for future particle detectors, the most relevant being: particle directionality information in a low energy threshold detector and improved particle identification. The CheSS experiment uses an array of small, fast photomultipliers (PMTs) and state-of-the-art electronics to demonstrate the reconstruction of a Cherenkov ring in liquid scintillator using two techniques: based on the photon density and using the photon hit time information. A charged particle ionizing a scintillation medium produces a prompt Cherenkov cone and late isotropic scintillation light, typically delayed by several ns. The fast response of our PMTs and DAQ provides a precision well below the ns level, making possible the time separation. Furthermore, the usage of the new developed water-based liquid scintillators (WbLS) enhances the separation since it allows tuning of the Cherenkov/Scintillation ratio. Latest results on the separation for pure liquid scintillators and WbLS will be presented.

Hydrogen migration modeling in a symmetric tilt boundary of the Iron-Chromium system

NASA Astrophysics Data System (ADS)

Ramunni, V. P.

2018-03-01

Previous experimental studies of H permeation in 9%Cr-Fe alloys have found a permeation coefficient 10 times lower and a diffusion coefficient 200 times lower than in pure annealed Fe. In an effort to shed some light on the microscopic origin of these findings, we perform an extensive study of Fe, Cr, and H migration in a high-angle symmetric tilt grain boundary in bcc Fe, both via vacancy and interstitial mechanism. This is undertaken in the framework of transition state theory with the relevant energies obtained from classical interatomic potentials, and partially from Density Functional Theory calculations, in order to check the consistency of structures. Trapping sites for H and possible migration paths are explored. We find that the presence of Cr and its migration via vacancy and interstitials creates the conditions in produce stable preferential trapping sites for H in the grain boundary, that delay the H migration, thereby explaining the experimental results.

MIT research in telerobotics

NASA Technical Reports Server (NTRS)

Sheridan, T. B.

1987-01-01

Ongoing MIT research in telerobotics (vehicles capable of some autonomous sensing and manipulating, having some remote supervisory control by people) and teleoperation (vehicles for sensing and manipulating which are fully controlled remotely by people) is discussed. The current efforts mix human and artificial intelligence/control. The idea of adjustable impedance at either end of pure master-slave teleoperation, and simultaneous coordinated control of teleoperator/telerobotic systems which have more than six degrees of freedom (e.g., a combined vehicle and arm, each with five or six DOF) are discussed. A new cable-controlled parallel link arm which offers many advantages over conventional arms for space is briefly described. Predictor displays to compensate for time delay in teleoperator loops, the use of state estimation to help human control decisions in space, and ongoing research in supervisory command language are covered. Finally, efforts to build a human flyable real-time dynamic computer-graphic telerobot simulator are described. These projects represent most, but not all, of the telerobotics research in our laboratory, supported by JPL, NASA Ames and NOAA.

Raman spectroscopic studies on bacteria

NASA Astrophysics Data System (ADS)

Maquelin, Kees; Choo-Smith, Lin-P'ing; Endtz, Hubert P.; Bruining, Hajo A.; Puppels, Gerwin J.

2000-11-01

Routine clinical microbiological identification of pathogenic micro-organisms is largely based on nutritional and biochemical tests. Laboratory results can be presented to a clinician after 2 - 3 days for most clinically relevant micro- organisms. Most of this time is required to obtain pure cultures and enough biomass for the tests to be performed. In the case of severely ill patients, this unavoidable time delay associated with such identification procedures can be fatal. A novel identification method based on confocal Raman microspectroscopy will be presented. With this method it is possible to obtain Raman spectra directly from microbial microcolonies on the solid culture medium, which have developed after only 6 hours of culturing for most commonly encountered organisms. Not only does this technique enable rapid (same day) identifications, but also preserves the sample allowing it to be double-checked with traditional tests. This, combined with the speed and minimal sample handling indicate that confocal Raman microspectroscopy has much potential as a powerful new tool in clinical diagnostic microbiology.

Delay-range-dependent chaos synchronization approach under varying time-lags and delayed nonlinear coupling.

PubMed

Zaheer, Muhammad Hamad; Rehan, Muhammad; Mustafa, Ghulam; Ashraf, Muhammad

2014-11-01

This paper proposes a novel state feedback delay-range-dependent control approach for chaos synchronization in coupled nonlinear time-delay systems. The coupling between two systems is esteemed to be nonlinear subject to time-lags. Time-varying nature of both the intrinsic and the coupling delays is incorporated to broad scope of the present study for a better-quality synchronization controller synthesis. Lyapunov-Krasovskii (LK) functional is employed to derive delay-range-dependent conditions that can be solved by means of the conventional linear matrix inequality (LMI)-tools. The resultant control approach for chaos synchronization of the master-slave time-delay systems considers non-zero lower bound of the intrinsic as well as the coupling time-delays. Further, the delay-dependent synchronization condition has been established as a special case of the proposed LK functional treatment. Furthermore, a delay-range-dependent condition, independent of the delay-rate, has been provided to address the situation when upper bound of the delay-derivative is unknown. A robust state feedback control methodology is formulated for synchronization of the time-delay chaotic networks against the L2 norm bounded perturbations by minimizing the L2 gain from the disturbance to the synchronization error. Numerical simulation results are provided for the time-delay chaotic networks to show effectiveness of the proposed delay-range-dependent chaos synchronization methodologies. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Mimics and chameleons in motor neurone disease

PubMed Central

Turner, Martin R; Talbot, Kevin

2013-01-01

The progression of motor neurone disease (MND) is currently irreversible, and the grave implications of diagnosis naturally fuels concern among neurologists over missing a potential mimic disorder. There is no diagnostic test for MND but in reality there are few plausible mimics in routine clinical practice. In the presence of a progressive pure motor disorder, signs such as florid fasciculations, bilateral tongue wasting, the ‘split hand’, head drop, emotionality, and cognitive or behavioural impairment carry high positive predictive value. MND is clinically heterogeneous, however, with some important chameleon-like presentations and considerable variation in clinical course. Lack of confidence about the scope of such variation, or an approach to diagnosis emphasising investigations over clinical common sense, has the potential to exacerbate diagnostic delay in MND and impede timely planning of the care which is essential to maximising quality of life. PMID:23616620

Downhole delay assembly for blasting with series delay

DOEpatents

Ricketts, Thomas E.

1982-01-01

A downhole delay assembly is provided which can be placed into a blasthole for initiation of explosive in the blasthole. The downhole delay assembly includes at least two detonating time delay devices in series in order to effect a time delay of longer than about 200 milliseconds in a round of explosions. The downhole delay assembly provides a protective housing to prevent detonation of explosive in the blasthole in response to the detonation of the first detonating time delay device. There is further provided a connection between the first and second time delay devices. The connection is responsive to the detonation of the first detonating time delay device and initiates the second detonating time delay device. A plurality of such downhole delay assemblies are placed downhole in unfragmented formation and are initiated simultaneously for providing a round of explosive expansions. The explosive expansions can be used to form an in situ oil shale retort containing a fragmented permeable mass of formation particles.

Parenting Predictors of Delay Inhibition in Socioeconomically Disadvantaged Preschoolers

PubMed Central

Merz, Emily C.; Landry, Susan H.; Zucker, Tricia A.; Barnes, Marcia A.; Assel, Michael; Taylor, Heather B.; Lonigan, Christopher J.; Phillips, Beth M.; Clancy-Menchetti, Jeanine; Eisenberg, Nancy; Spinrad, Tracy L.; Valiente, Carlos; de Villiers, Jill; Consortium, the School Readiness Research

2016-01-01

This study examined longitudinal associations between specific parenting factors and delay inhibition in socioeconomically disadvantaged preschoolers. At Time 1, parents and 2- to 4-year-old children (mean age = 3.21 years; N = 247) participated in a videotaped parent-child free play session, and children completed delay inhibition tasks (gift delay-wrap, gift delay-bow, and snack delay tasks). Three months later, at Time 2, children completed the same set of tasks. Parental responsiveness was coded from the parent-child free play sessions, and parental directive language was coded from transcripts of a subset of 127 of these sessions. Structural equation modeling was used, and covariates included age, gender, language skills, parental education, and Time 1 delay inhibition. Results indicated that in separate models, Time 1 parental directive language was significantly negatively associated with Time 2 delay inhibition, and Time 1 parental responsiveness was significantly positively associated with Time 2 delay inhibition. When these parenting factors were entered simultaneously, Time 1 parental directive language significantly predicted Time 2 delay inhibition whereas Time 1 parental responsiveness was no longer significant. Findings suggest that parental language that modulates the amount of autonomy allotted the child may be an important predictor of early delay inhibition skills. PMID:27833461

Time-delayed feedback control of diffusion in random walkers.

PubMed

Ando, Hiroyasu; Takehara, Kohta; Kobayashi, Miki U

2017-07-01

Time delay in general leads to instability in some systems, while specific feedback with delay can control fluctuated motion in nonlinear deterministic systems to a stable state. In this paper, we consider a stochastic process, i.e., a random walk, and observe its diffusion phenomenon with time-delayed feedback. As a result, the diffusion coefficient decreases with increasing delay time. We analytically illustrate this suppression of diffusion by using stochastic delay differential equations and justify the feasibility of this suppression by applying time-delayed feedback to a molecular dynamics model.

Impact of Sodium Tungstate and Tungsten Alloys on the Growth of Selected Microorganisms with Environmental Significance

DTIC Science & Technology

2010-07-30

TUNGSTEN ALLOYS ON THE GROWTH OF SELECTED MICROORGANISMS WITH ENVIROMENTAL SIGNIFICANCE 5a. Contract Number: 5b. Grant Number: 5c. Program Element...lower tolerances. Interestingly, bacteria cultivated from the environment displayed only minor delays and reduction in growth relative to pure...settings where nutrients may be limited. 15. SUBJECT TERMS Tungsten, sodium tungstate, microbial growth , environmental microbiology, bacteria , Shewanella

Noncoherent detection of periodic signals

NASA Technical Reports Server (NTRS)

Gagliardi, R. M.

1974-01-01

The optimal Bayes detector for a general periodic waveform having uniform delay and additive white Gaussian noise is examined. It is shown that the detector is much more complex than that for the well known cases of pure sine waves (i.e. classical noncoherent detection) and narrowband signals. An interpretation of the optimal processing is presented, and several implementations are discussed. The results have application to the noncoherent detection of optical square waves.

Effect of gamma irradiation and storage time on microbial growth and physicochemical characteristics of pumpkin (Cucurbita Moschata Duchesne ex Poiret) puree.

PubMed

Gliemmo, María F; Latorre, María E; Narvaiz, Patricia; Campos, Carmen A; Gerschenson, Lía N

2014-01-01

The effect of gamma irradiation (0-2 kGy) and storage time (0-28 days) on microbial growth and physicochemical characteristics of a packed pumpkin puree was studied. For that purpose, a factorial design was applied. The puree contained potassium sorbate, glucose and vanillin was stored at 25°C . Gamma irradiation diminished and storage time increased microbial growth. A synergistic effect between both variables on microbial growth was observed. Storage time decreased pH and color of purees. Sorbate content decreased with storage time and gamma irradiation. Mathematical models of microbial growth generated by the factorial design allowed estimating that a puree absorbing 1.63 kGy would have a shelf-life of 4 days. In order to improve this time, some changes in the applied hurdles were assayed. These included a thermal treatment before irradiation, a reduction of irradiation dose to 0.75 kGy and a decrease in storage temperature at 20°C . As a result, the shelf-life of purees increased to 28 days.

Effects of partial time delays on phase synchronization in Watts-Strogatz small-world neuronal networks

NASA Astrophysics Data System (ADS)

Sun, Xiaojuan; Perc, Matjaž; Kurths, Jürgen

2017-05-01

In this paper, we study effects of partial time delays on phase synchronization in Watts-Strogatz small-world neuronal networks. Our focus is on the impact of two parameters, namely the time delay τ and the probability of partial time delay pdelay, whereby the latter determines the probability with which a connection between two neurons is delayed. Our research reveals that partial time delays significantly affect phase synchronization in this system. In particular, partial time delays can either enhance or decrease phase synchronization and induce synchronization transitions with changes in the mean firing rate of neurons, as well as induce switching between synchronized neurons with period-1 firing to synchronized neurons with period-2 firing. Moreover, in comparison to a neuronal network where all connections are delayed, we show that small partial time delay probabilities have especially different influences on phase synchronization of neuronal networks.

Effect of time delay on surgical performance during telesurgical manipulation.

PubMed

Fabrizio, M D; Lee, B R; Chan, D Y; Stoianovici, D; Jarrett, T W; Yang, C; Kavoussi, L R

2000-03-01

Telementoring allows a less experienced surgeon to benefit from an expert surgical consultation, reducing cost, travel, and the learning curve associated with new procedures. However, there are several technical limitations that affect practical applications. One potentially serious problem is the time delay that occurs any time data are transferred across long distances. To date, the effect of time delay on surgical performance has not been studied. A two-phase trial was designed to examine the effect of time delay on surgical performance. In the first phase, a series of tasks was performed, and the numbers of robotic movements required for completion was counted. Programmed incremental time delays were made in audiovisual acquisition and robotic controls. The number of errors made while performing each task at various time delay intervals was noted. In the second phase, a remote surgeon in Baltimore performed the tasks 9000 miles away in Singapore. The number of errors made was recorded. As the time delay increased, the number of operator errors increased. The accuracy needed to perform remote robotic procedures was diminished as the time delay increased. A learning curve did exist for each task, but as the time delay interval increased, it took longer to complete the task. Time delay does affect surgical performance. There is an acceptable delay of <700 msec in which surgeons can compensate for this phenomenon. Clinical studies will be needed to evaluate the true impact of time delay.

Finite time synchronization of memristor-based Cohen-Grossberg neural networks with mixed delays.

PubMed

Chen, Chuan; Li, Lixiang; Peng, Haipeng; Yang, Yixian

2017-01-01

Finite time synchronization, which means synchronization can be achieved in a settling time, is desirable in some practical applications. However, most of the published results on finite time synchronization don't include delays or only include discrete delays. In view of the fact that distributed delays inevitably exist in neural networks, this paper aims to investigate the finite time synchronization of memristor-based Cohen-Grossberg neural networks (MCGNNs) with both discrete delay and distributed delay (mixed delays). By means of a simple feedback controller and novel finite time synchronization analysis methods, several new criteria are derived to ensure the finite time synchronization of MCGNNs with mixed delays. The obtained criteria are very concise and easy to verify. Numerical simulations are presented to demonstrate the effectiveness of our theoretical results.

Gravitational lens recovery with GLASS: measuring the mass profile and shape of a lens

NASA Astrophysics Data System (ADS)

Coles, Jonathan P.; Read, Justin I.; Saha, Prasenjit

2014-12-01

We use a new non-parametric gravitational modelling tool - GLASS - to determine what quality of data (strong lensing, stellar kinematics, and/or stellar masses) are required to measure the circularly averaged mass profile of a lens and its shape. GLASS uses an underconstrained adaptive grid of mass pixels to model the lens, searching through thousands of models to marginalize over model uncertainties. Our key findings are as follows: (i) for pure lens data, multiple sources with wide redshift separation give the strongest constraints as this breaks the well-known mass-sheet or steepness degeneracy; (ii) a single quad with time delays also performs well, giving a good recovery of both the mass profile and its shape; (iii) stellar masses - for lenses where the stars dominate the central potential - can also break the steepness degeneracy, giving a recovery for doubles almost as good as having a quad with time-delay data, or multiple source redshifts; (iv) stellar kinematics provide a robust measure of the mass at the half-light radius of the stars r1/2 that can also break the steepness degeneracy if the Einstein radius rE ≠ r1/2; and (v) if rE ˜ r1/2, then stellar kinematic data can be used to probe the stellar velocity anisotropy β - an interesting quantity in its own right. Where information on the mass distribution from lensing and/or other probes becomes redundant, this opens up the possibility of using strong lensing to constrain cosmological models.

Time-delayed chameleon: Analysis, synchronization and FPGA implementation

NASA Astrophysics Data System (ADS)

Rajagopal, Karthikeyan; Jafari, Sajad; Laarem, Guessas

2017-12-01

In this paper we report a time-delayed chameleon-like chaotic system which can belong to different families of chaotic attractors depending on the choices of parameters. Such a characteristic of self-excited and hidden chaotic flows in a simple 3D system with time delay has not been reported earlier. Dynamic analysis of the proposed time-delayed systems are analysed in time-delay space and parameter space. A novel adaptive modified functional projective lag synchronization algorithm is derived for synchronizing identical time-delayed chameleon systems with uncertain parameters. The proposed time-delayed systems and the synchronization algorithm with controllers and parameter estimates are then implemented in FPGA using hardware-software co-simulation and the results are presented.

The time delay in strong gravitational lensing with Gauss-Bonnet correction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Man, Jingyun; Cheng, Hongbo, E-mail: jingyunman@mail.ecust.edu.cn, E-mail: hbcheng@ecust.edu.cn

2014-11-01

The time delay between two relativistic images in the strong gravitational lensing governed by Gauss-Bonnet gravity is studied. We make a complete analytical derivation of the expression of time delay in presence of Gauss-Bonnet coupling. With respect to Schwarzschild, the time delay decreases as a consequence of the shrinking of the photon sphere. As the coupling increases, the second term in the time delay expansion becomes more relevant. Thus time delay in strong limit encodes some new information about geometry in five-dimensional spacetime with Gauss-Bonnet correction.

Diagnostic value of three-dimensional magnetic resonance imaging of inner ear after intratympanic gadolinium injection, and clinical application of magnetic resonance imaging scoring system in patients with delayed endolymphatic hydrops.

PubMed

Gu, X; Fang, Z-M; Liu, Y; Lin, S-L; Han, B; Zhang, R; Chen, X

2014-01-01

Three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging of the inner ear after intratympanic injection of gadolinium, together with magnetic resonance imaging scoring of the perilymphatic space, were used to investigate the positive identification rate of hydrops and determine the technique's diagnostic value for delayed endolymphatic hydrops. Twenty-five patients with delayed endolymphatic hydrops underwent pure tone audiometry, bithermal caloric testing, vestibular-evoked myogenic potential testing and three-dimensional magnetic resonance imaging of the inner ear after bilateral intratympanic injection of gadolinium. The perilymphatic space of the scanned images was analysed to investigate the positive identification rate of endolymphatic hydrops. According to the magnetic resonance imaging scoring of the perilymphatic space and the diagnostic standard, 84 per cent of the patients examined had endolymphatic hydrops. In comparison, the positive identification rates for vestibular-evoked myogenic potential and bithermal caloric testing were 52 per cent and 72 per cent respectively. Three-dimensional magnetic resonance imaging after intratympanic injection of gadolinium is valuable in the diagnosis of delayed endolymphatic hydrops and its classification. The perilymphatic space scoring system improved the diagnostic accuracy of magnetic resonance imaging.

Performance of an Automated System for Control of Traffic in Terminal Airspace

NASA Technical Reports Server (NTRS)

Nikoleris, Tasos; Erzberger, Heinz; Paielli, Russell A.; Chu, Yung-Cheng

2016-01-01

This paper examines the performance of a system that performs automated conflict resolution and arrival scheduling for aircraft in the terminal airspace around major airports. Such a system has the potential to perform separation assurance and arrival sequencing tasks that are currently handled manually by human controllers. The performance of the system is tested against several simulated traffic scenarios that are characterized by the rate at which air traffic is metered into the terminal airspace. For each traffic scenario, the levels of performance that are examined include: number of conflicts predicted to occur, types of resolution maneuver used to resolve predicted conflicts, and the amount of delay for all flights. The simulation results indicate that the percentage of arrivals that required a maneuver that changes the flight's horizontal route ranged between 11% and 15% in all traffic scenarios. That finding has certain implications if this automated system were to be implemented simply as a decision support tool. It is also found that arrival delay due to purely wake vortex separation requirements on final approach constituted only between 29% and 35% of total arrival delay, while the remaining major portion of it is mainly due to delay back propagation effects.

Early life traits of farm and wild Atlantic salmon Salmo salar and first generation hybrids in the south coast of Newfoundland.

PubMed

Hamoutene, D; Perez-Casanova, J; Burt, K; Lush, L; Caines, J; Collier, C; Hinks, R

2017-06-01

This study examined fertilization rates, survival and early life-trait differences of pure farm, wild and first generation (F1) hybrid origin embryos after crossing farm and wild Atlantic salmon Salmo salar. Results show that despite a trend towards higher in vitro fertilization success for wild females, differences in fertilization success in river water are not significantly different among crosses. In a hatchery environment, wild females' progeny (pure wild and hybrids with wild maternal parent) hatched 7-11 days earlier than pure farm crosses and hybrids with farm maternal parents. In addition, pure wild progeny had higher total lengths (L T ) at hatch than pure farm crosses and hybrids. Directions in trait differences need to be tested in a river environment, but results clearly show the maternal influence on early stages beyond egg-size differences. Differences in L T were no longer significant at 70 days post hatch (shortly after the onset of exogenous feeding) showing the need to investigate later developmental stages to better assess somatic growth disparities due to genetic differences. Higher mortality rates of the most likely hybrids (farm female × wild male hybrids) at egg and fry stages and their delayed hatch suggest that these F1 hybrids might be less likely to survive the early larval stages than wild stocks. © 2017 Her Majesty the Queen in Right of Canada. Journal of Fish Biology © 2017 The Fisheries Society of the British Isles.

Effect of Time Delay on Recognition Memory for Pictures: The Modulatory Role of Emotion

PubMed Central

Wang, Bo

2014-01-01

This study investigated the modulatory role of emotion in the effect of time delay on recognition memory for pictures. Participants viewed neutral, positive and negative pictures, and took a recognition memory test 5 minutes, 24 hours, or 1 week after learning. The findings are: 1) For neutral, positive and negative pictures, overall recognition accuracy in the 5-min delay did not significantly differ from that in the 24-h delay. For neutral and positive pictures, overall recognition accuracy in the 1-week delay was lower than in the 24-h delay; for negative pictures, overall recognition in the 24-h and 1-week delay did not significantly differ. Therefore negative emotion modulates the effect of time delay on recognition memory, maintaining retention of overall recognition accuracy only within a certain frame of time. 2) For the three types of pictures, recollection and familiarity in the 5-min delay did not significantly differ from that in the 24-h and the 1-week delay. Thus emotion does not appear to modulate the effect of time delay on recollection and familiarity. However, recollection in the 24-h delay was higher than in the 1-week delay, whereas familiarity in the 24-h delay was lower than in the 1-week delay. PMID:24971457

Angular dependence of EWS time delay for photoionization of @Xe

NASA Astrophysics Data System (ADS)

Mandal, Ankur; Deshmukh, Pranawa; Kheifets, Anatoli; Dolmatov, Valeriy; Manson, Steven

2017-04-01

Interference between photoionization channels leads to angular dependence in photoionization time delay. Angular dependence is found to be a common effect for two-photon absorption experiments very recently. The effect of confinement on the time delay where each partial wave contributions to the ionization are studied. In this work we report angular dependence and confinement effects on Eisenbud-Wigner-Smith (EWS) time delay in atomic photoionization. Using and we computed the EWS time delay for free and confined Xe atom for photoionization from inner 4d3/2 and 4d5/2 and outer 5p1/2 and 5p3/2 subshells at various angles. The calculated EWS time delay is few tens to few hundreds of attoseconds (10-18 second). The photoionization time delay for @Xe follows that in the free Xe atom on which the confinement oscillations are built. The present work reveals the effect of confinement on the photoionization time delay at different angles between photoelectron ejection and the photon polarization.

Crash testing difference-smoothing algorithm on a large sample of simulated light curves from TDC1

NASA Astrophysics Data System (ADS)

Rathna Kumar, S.

2017-09-01

In this work, we propose refinements to the difference-smoothing algorithm for the measurement of time delay from the light curves of the images of a gravitationally lensed quasar. The refinements mainly consist of a more pragmatic approach to choose the smoothing time-scale free parameter, generation of more realistic synthetic light curves for the estimation of time delay uncertainty and using a plot of normalized χ2 computed over a wide range of trial time delay values to assess the reliability of a measured time delay and also for identifying instances of catastrophic failure. We rigorously tested the difference-smoothing algorithm on a large sample of more than thousand pairs of simulated light curves having known true time delays between them from the two most difficult 'rungs' - rung3 and rung4 - of the first edition of Strong Lens Time Delay Challenge (TDC1) and found an inherent tendency of the algorithm to measure the magnitude of time delay to be higher than the true value of time delay. However, we find that this systematic bias is eliminated by applying a correction to each measured time delay according to the magnitude and sign of the systematic error inferred by applying the time delay estimator on synthetic light curves simulating the measured time delay. Following these refinements, the TDC performance metrics for the difference-smoothing algorithm are found to be competitive with those of the best performing submissions of TDC1 for both the tested 'rungs'. The MATLAB codes used in this work and the detailed results are made publicly available.

Polymorphic Transformation in Mixtures of High- and Low-Melting Fractions of Milk Fat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cisneros,A.; Mazzanti, G.; Campos, R.

2006-01-01

The kinetics of crystallization of high-melting fraction (HMF) and a mixture of 40% HMF and 60% low-melting fraction (LMF) of milk fat were studied at 5 C by time-resolved in-situ synchrotron X-ray diffraction. HMF crystallized in the {alpha} polymorph, had a longer lifetime than the ones previously reported in pure milk fat, and was almost completely solid. The HMF/LMF mixture crystallized initially in the {alpha} form and transformed into the {beta}' polymorph, with a solid fat content much lower than that of HMF. The polymorphic change was therefore attributed to a delayed sudden formation of {beta}' mixed crystals from themore » uncrystallized melt. These findings are important for the food industry and as fundamental knowledge to improve our understanding of the origin of the macroscopic physical properties of solid milk fat fractions used in many manufacturing processes.« less

Comparison of delay enhancement mechanisms for SBS-based slow light systems.

PubMed

Schneider, Thomas; Henker, Ronny; Lauterbach, Kai-Uwe; Junker, Markus

2007-07-23

We compare two simple mechanisms for the enhancement of the time delay in slow light systems. Both are based on the superposition of the Brillouin gain with additional loss. As we will show in theory and experiment if two losses are placed at the wings of a SBS gain, contrary to other methods, the loss power increases the time delay. This leads to higher delay times at lower optical powers and to an increase of the zero gain delay of more than 50%. With this method we achieved a time delay of more than 120ns for pulses with a temporal width of 30ns. To the best of our knowledge, this is the highest time delay in just one fiber spool. Beside the enhancement of the time delay the method could have the potential to decrease the pulse distortions for high bit rate signals.

Impact of Partial Time Delay on Temporal Dynamics of Watts-Strogatz Small-World Neuronal Networks

NASA Astrophysics Data System (ADS)

Yan, Hao; Sun, Xiaojuan

2017-06-01

In this paper, we mainly discuss effects of partial time delay on temporal dynamics of Watts-Strogatz (WS) small-world neuronal networks by controlling two parameters. One is the time delay τ and the other is the probability of partial time delay pdelay. Temporal dynamics of WS small-world neuronal networks are discussed with the aid of temporal coherence and mean firing rate. With the obtained simulation results, it is revealed that for small time delay τ, the probability pdelay could weaken temporal coherence and increase mean firing rate of neuronal networks, which indicates that it could improve neuronal firings of the neuronal networks while destroying firing regularity. For large time delay τ, temporal coherence and mean firing rate do not have great changes with respect to pdelay. Time delay τ always has great influence on both temporal coherence and mean firing rate no matter what is the value of pdelay. Moreover, with the analysis of spike trains and histograms of interspike intervals of neurons inside neuronal networks, it is found that the effects of partial time delays on temporal coherence and mean firing rate could be the result of locking between the period of neuronal firing activities and the value of time delay τ. In brief, partial time delay could have great influence on temporal dynamics of the neuronal networks.

Piloted simulator study of allowable time delay in pitch flight control system of a transport airplane with negative static stability

NASA Technical Reports Server (NTRS)

Grantham, William D.; Smith, Paul M.; Person, Lee H., Jr.; Meyer, Robert T.; Tingas, Stephen A.

1987-01-01

A piloted simulation study was conducted to determine the permissible time delay in the flight control system of a 10-percent statically unstable transport airplane during cruise flight conditions. The math model used for the simulation was a derivative Lockheed L-1011 wide-body jet transport. Data were collected and analyzed from a total of 137 cruising flights in both calm- and turbulent-air conditions. Results of this piloted simulation study verify previous findings that show present military specifications for allowable control-system time delay may be too stringent when applied to transport-size airplanes. Also, the degree of handling-qualities degradation due to time delay is shown to be strongly dependent on the source of the time delay in an advanced flight control system. Maximum allowable time delay for each source of time delay in the control system, in addition to a less stringent overall maximum level of time delay, should be considered for large aircraft. Preliminary results also suggest that adverse effects of control-system time delay may be at least partially offset by variations in control gearing. It is recommended that the data base include different airplane baselines, control systems, and piloting tasks with many pilots participating, so that a reasonable set of limits for control-system time delay can be established to replace the military specification limits currently being used.

76 FR 68734 - Taking and Importing Marine Mammals: Taking Marine Mammals Incidental to Navy Training Exercises...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-07

... marine mammal is likely to travel during the time associated with the TDFD's time delay, and that... Navy provided the approximate distance that an animal would typically travel within a given time-delay... Speed and Length of Time-Delay Potential distance Species group Swim speed Time-delay traveled Delphinid...

Probability of Loss of Assured Safety in Systems with Multiple Time-Dependent Failure Modes: Incorporation of Delayed Link Failure in the Presence of Aleatory Uncertainty.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Helton, Jon C.; Brooks, Dusty Marie; Sallaberry, Cedric Jean-Marie.

Probability of loss of assured safety (PLOAS) is modeled for weak link (WL)/strong link (SL) systems in which one or more WLs or SLs could potentially degrade into a precursor condition to link failure that will be followed by an actual failure after some amount of elapsed time. The following topics are considered: (i) Definition of precursor occurrence time cumulative distribution functions (CDFs) for individual WLs and SLs, (ii) Formal representation of PLOAS with constant delay times, (iii) Approximation and illustration of PLOAS with constant delay times, (iv) Formal representation of PLOAS with aleatory uncertainty in delay times, (v) Approximationmore » and illustration of PLOAS with aleatory uncertainty in delay times, (vi) Formal representation of PLOAS with delay times defined by functions of link properties at occurrence times for failure precursors, (vii) Approximation and illustration of PLOAS with delay times defined by functions of link properties at occurrence times for failure precursors, and (viii) Procedures for the verification of PLOAS calculations for the three indicated definitions of delayed link failure.« less

Time delay can facilitate coherence in self-driven interacting-particle systems

NASA Astrophysics Data System (ADS)

Sun, Yongzheng; Lin, Wei; Erban, Radek

2014-12-01

Directional switching in a self-propelled particle model with delayed interactions is investigated. It is shown that the average switching time is an increasing function of time delay. The presented results are applied to studying collective animal behavior. It is argued that self-propelled particle models with time delays can explain the state-dependent diffusion coefficient measured in experiments with locust groups. The theory is further generalized to heterogeneous groups where each individual can respond to its environment with a different time delay.

Delay banking for air traffic management

NASA Technical Reports Server (NTRS)

Green, Steven M. (Inventor)

2007-01-01

A method and associated system for time delay banking for aircraft arrival time, aircraft departure time and/or en route flight position. The delay credit value for a given flight may decrease with passage of time and may be transferred to or traded with other flights having the same or a different user (airline owner or operator). The delay credit value for a given aircraft flight depends upon an initial delay credit value, which is determined by a central system and depends upon one or more other flight characteristics. Optionally, the delay credit value decreases with passage of time. Optionally, a transaction cost is assessed against a delay credit value that is used on behalf of another flight with the same user or is traded with a different user.

General relation between the group delay and dwell time in multicomponent electron systems

NASA Astrophysics Data System (ADS)

Zhai, Feng; Lu, Junqiang

2016-10-01

For multicomponent electron scattering states, we derive a general relation between the Wigner group delay and the Bohmian dwell time. It is found that the definition of group delay should account for the phase of the spinor wave functions of propagating modes. The difference between the group delay and dwell time comes from both the interference delay and the decaying modes. For barrier tunneling of helical electrons on a surface of topological insulators, our calculations including the trigonal-warping term show that the decaying modes can contribute greatly to the group delay. The derived relation between the group delay and the dwell time is helpful to unify the two definitions of tunneling time in a quite general situation.

CAN LARGE TIME DELAYS OBSERVED IN LIGHT CURVES OF CORONAL LOOPS BE EXPLAINED IN IMPULSIVE HEATING?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lionello, Roberto; Linker, Jon A.; Mikić, Zoran

The light curves of solar coronal loops often peak first in channels associated with higher temperatures and then in those associated with lower temperatures. The delay times between the different narrowband EUV channels have been measured for many individual loops and recently for every pixel of an active region observation. The time delays between channels for an active region exhibit a wide range of values. The maximum time delay in each channel pair can be quite large, i.e., >5000 s. These large time delays make-up 3%–26% (depending on the channel pair) of the pixels where a trustworthy, positive time delaymore » is measured. It has been suggested that these time delays can be explained by simple impulsive heating, i.e., a short burst of energy that heats the plasma to a high temperature, after which the plasma is allowed to cool through radiation and conduction back to its original state. In this paper, we investigate whether the largest observed time delays can be explained by this hypothesis by simulating a series of coronal loops with different heating rates, loop lengths, abundances, and geometries to determine the range of expected time delays between a set of four EUV channels. We find that impulsive heating cannot address the largest time delays observed in two of the channel pairs and that the majority of the large time delays can only be explained by long, expanding loops with photospheric abundances. Additional observations may rule out these simulations as an explanation for the long time delays. We suggest that either the time delays found in this manner may not be representative of real loop evolution, or that the impulsive heating and cooling scenario may be too simple to explain the observations, and other potential heating scenarios must be explored.« less

Cognitive person variables in the delay of gratification of older children at risk.

PubMed

Rodriguez, M L; Mischel, W; Shoda, Y

1989-08-01

The components of self-regulation were analyzed, extending the self-imposed delay of gratification paradigm to older children with social adjustment problems. Delay behavior was related to a network of conceptually relevant cognitive person variables, consisting of attention deployment strategies during delay, knowledge of delay rules, and intelligence. A positive relationship was demonstrated between concurrent indexes of intelligence, attention deployment, and actual delay time. Moreover, attention deployment, measured as an individual differences variable during the delay process, had a direct, positive effect on delay behavior. Specifically, as the duration of delay and the frustration of the situation increased, children who spent a higher proportion of the time distracting themselves from the tempting elements of the delay situation were able to delay longer. The effect of attention deployment on delay behavior was significant even when age, intelligence, and delay rule knowledge were controlled. Likewise, delay rule knowledge significantly predicted delay time, even when age, attention deployment, and intelligence were controlled.

Compendium of Experimental Cetane Numbers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yanowitz, J.; Ratcliff, M. A.; McCormick, R. L.

This report is an updated version of the 2004 Compendium of Experimental Cetane Number Data and presents a compilation of measured cetane numbers for pure chemical compounds. It includes all available single compound cetane number data found in the scientific literature up until March 2014 as well as a number of unpublished values, most measured over the past decade at the National Renewable Energy Laboratory. This Compendium contains cetane values for 389 pure compounds, including 189 hydrocarbons and 201 oxygenates. More than 250 individual measurements are new to this version of the Compendium. For many compounds, numerous measurements are included,more » often collected by different researchers using different methods. Cetane number is a relative ranking of a fuel's autoignition characteristics for use in compression ignition engines; it is based on the amount of time between fuel injection and ignition, also known as ignition delay. The cetane number is typically measured either in a single-cylinder engine or a constant volume combustion chamber. Values in the previous Compendium derived from octane numbers have been removed, and replaced with a brief analysis of the correlation between cetane numbers and octane numbers. The discussion on the accuracy and precision of the most commonly used methods for measuring cetane has been expanded and the data has been annotated extensively to provide additional information that will help the reader judge the relative reliability of individual results.« less

Firing patterns transition and desynchronization induced by time delay in neural networks

NASA Astrophysics Data System (ADS)

Huang, Shoufang; Zhang, Jiqian; Wang, Maosheng; Hu, Chin-Kun

2018-06-01

We used the Hindmarsh-Rose (HR) model (Hindmarsh and Rose, 1984) to study the effect of time delay on the transition of firing behaviors and desynchronization in neural networks. As time delay is increased, neural networks exhibit diversity of firing behaviors, including regular spiking or bursting and firing patterns transitions (FPTs). Meanwhile, the desynchronization of firing and unstable bursting with decreasing amplitude in neural system, are also increasingly enhanced with the increase of time delay. Furthermore, we also studied the effect of coupling strength and network randomness on these phenomena. Our results imply that time delays can induce transition and desynchronization of firing behaviors in neural networks. These findings provide new insight into the role of time delay in the firing activities of neural networks, and can help to better understand the firing phenomena in complex systems of neural networks. A possible mechanism in brain that can cause the increase of time delay is discussed.

Delay time in a single barrier for a movable quantum shutter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernandez, Alberto

2010-05-15

The transient solution and delay time for a {delta} potential scatterer with a movable quantum shutter is calculated by solving analytically the time-dependent Schroedinger equation. The delay time is analyzed as a function of the distance between the shutter and the potential barrier and also as a function of the distance between the potential barrier and the detector. In both cases, it is found that the delay time exhibits a dynamical behavior and that it tends to a saturation value {Delta}t{sub sat} in the limit of very short distances, which represents the maximum delay produced by the potential barrier nearmore » the interaction region. The phase time {tau}{sub {theta},} on the other hand, is not an appropriate time scale for measuring the time delay near the interaction region, except if the shutter is moved far away from the potential. The role played by the antibound state of the system on the behavior of the delay time is also discussed.« less

LiDAR-IMU Time Delay Calibration Based on Iterative Closest Point and Iterated Sigma Point Kalman Filter.

PubMed

Liu, Wanli

2017-03-08

The time delay calibration between Light Detection and Ranging (LiDAR) and Inertial Measurement Units (IMUs) is an essential prerequisite for its applications. However, the correspondences between LiDAR and IMU measurements are usually unknown, and thus cannot be computed directly for the time delay calibration. In order to solve the problem of LiDAR-IMU time delay calibration, this paper presents a fusion method based on iterative closest point (ICP) and iterated sigma point Kalman filter (ISPKF), which combines the advantages of ICP and ISPKF. The ICP algorithm can precisely determine the unknown transformation between LiDAR-IMU; and the ISPKF algorithm can optimally estimate the time delay calibration parameters. First of all, the coordinate transformation from the LiDAR frame to the IMU frame is realized. Second, the measurement model and time delay error model of LiDAR and IMU are established. Third, the methodology of the ICP and ISPKF procedure is presented for LiDAR-IMU time delay calibration. Experimental results are presented that validate the proposed method and demonstrate the time delay error can be accurately calibrated.

On Time Delay Margin Estimation for Adaptive Control and Optimal Control Modification

NASA Technical Reports Server (NTRS)

Nguyen, Nhan T.

2011-01-01

This paper presents methods for estimating time delay margin for adaptive control of input delay systems with almost linear structured uncertainty. The bounded linear stability analysis method seeks to represent an adaptive law by a locally bounded linear approximation within a small time window. The time delay margin of this input delay system represents a local stability measure and is computed analytically by three methods: Pade approximation, Lyapunov-Krasovskii method, and the matrix measure method. These methods are applied to the standard model-reference adaptive control, s-modification adaptive law, and optimal control modification adaptive law. The windowing analysis results in non-unique estimates of the time delay margin since it is dependent on the length of a time window and parameters which vary from one time window to the next. The optimal control modification adaptive law overcomes this limitation in that, as the adaptive gain tends to infinity and if the matched uncertainty is linear, then the closed-loop input delay system tends to a LTI system. A lower bound of the time delay margin of this system can then be estimated uniquely without the need for the windowing analysis. Simulation results demonstrates the feasibility of the bounded linear stability method for time delay margin estimation.

Craniosynostosis in 10q26 deletion patients: A consequence of brain underdevelopment or altered suture biology?

PubMed

Faria, Ágatha Cristhina; Rabbi-Bortolini, Eliete; Rebouças, Maria R G O; de S Thiago Pereira, Andréia L A; Frasson, Milena G Tonini; Atique, Rodrigo; Lourenço, Naila Cristina V; Rosenberg, Carla; Kobayashi, Gerson S; Passos-Bueno, Maria Rita; Errera, Flávia Imbroisi Valle

2016-02-01

Approximately a hundred patients with terminal 10q deletions have been described. They present with a wide range of clinical features always accompanied by delayed development, intellectual disability and craniofacial dysmorphisms. Here, we report a girl and a boy with craniosynostosis, developmental delay and other congenital anomalies. Karyotyping and molecular analysis including Multiplex Ligation dependent probe amplification (MLPA) and Array Comparative Genomic Hybridization (aCGH) were performed in both patients. We detected a 13.1 Mb pure deletion at 10q26.12-q26.3 in the girl and a 10.9 Mb pure deletion at 10q26.13-q26.3 in the boy, both encompassing about 100 genes. The clinical and molecular findings in these patients reinforce the importance of the DOCK1 smallest region of overlap I (SRO I), previously suggested to explain the clinical signs, and together with a review of the literature suggest a second 3.5 Mb region important for the phenotype (SRO II). Genotype-phenotype correlations and literature data suggest that the craniosynostosis is not directly related to dysregulated signaling in suture development, but may be secondary to alterations in brain development instead. Further, genes at 10q26 may be involved in the molecular crosstalk between brain and cranial vault. © 2015 Wiley Periodicals, Inc.

Leveraging delay discounting for health: Can time delays influence food choice?

PubMed

Appelhans, Bradley M; French, Simone A; Olinger, Tamara; Bogucki, Michael; Janssen, Imke; Avery-Mamer, Elizabeth F; Powell, Lisa M

2018-07-01

Delay discounting, the tendency to choose smaller immediate rewards over larger delayed rewards, is theorized to promote consumption of immediately rewarding but unhealthy foods at the expense of long-term weight maintenance and nutritional health. An untested implication of delay discounting models of decision-making is that selectively delaying access to less healthy foods may promote selection of healthier (immediately available) alternatives, even if they may be less desirable. The current study tested this hypothesis by measuring healthy versus regular vending machine snack purchasing before and during the implementation of a 25-s time delay on the delivery of regular snacks. Purchasing was also examined under a $0.25 discount on healthy snacks, a $0.25 tax on regular snacks, and the combination of both pricing interventions with the 25-s time delay. Across 32,019 vending sales from three separate vending locations, the 25-s time delay increased healthy snack purchasing from 40.1% to 42.5%, which was comparable to the impact of a $0.25 discount (43.0%). Combining the delay and the discount had a roughly additive effect (46.0%). However, the strongest effects were seen under the $0.25 tax on regular snacks (53.7%) and the combination of the delay and the tax (50.2%). Intervention effects varied substantially between vending locations. Importantly, time delays did not harm overall vending sales or revenue, which is relevant to the real-world feasibility of this intervention. More investigation is needed to better understand how the impact of time delays on food choice varies across populations, evaluate the effects of time delays on beverage vending choices, and extend this approach to food choices in contexts other than vending machines. ClinicalTrials.gov, NCT02359916. Copyright © 2018 Elsevier Ltd. All rights reserved.

An improved measurement system for FOG pure lag time with no changing of FOG work status

NASA Astrophysics Data System (ADS)

Chen, X.; Yang, J. H.; Zhou, Y. L.; Shu, X. W.

2018-05-01

The minimum pure lag time is an important factor for characterizing the dynamic performance of fiber optical gyroscope. It is defined as the time duration from the reception of velocity-shock signal to the output of corresponding fiber-optic gyroscope data. Many engineering projects have required for this index specifically, so the measurement of the minimum pure lag time is highly demanded. In typically measurement system, the work status of tested FOG has to be changed. In this work, a FOG pure lag time measurement system without changing the work status of the FOG has been demonstrated. During the operation of this test system, the impact structure generated a shock towards the FOG, and the pure lag time was measured through data processing analysis. The design scheme and test principle have been researched and analyzed in detail. And a prototype has been developed and used for experiment successfully. This measurement system can realize a measurement accuracy of better than ±3 μs and a system resolution of 108.6ns.

Effect of time delay on flying qualities: An update

NASA Technical Reports Server (NTRS)

Smith, R. E.; Sarrafian, S. K.

1986-01-01

Flying qualities problems of modern, full-authority electronic flight control systems are most often related to the introduction of additional time delay in aircraft response to a pilot input. These delays can have a significant effect on the flying qualities of the aircraft. Time delay effects are reexamined in light of recent flight test experience with aircraft incorporating new technology. Data from the X-29A forward-swept-wing demonstrator, a related preliminary in-flight experiment, and other flight observations are presented. These data suggest that the present MIL-F-8785C allowable-control system time delay specifications are inadequate or, at least, incomplete. Allowable time delay appears to be a function of the shape of the aircraft response following the initial delay. The cockpit feel system is discussed as a dynamic element in the flight control system. Data presented indicate that the time delay associated with a significant low-frequency feel system does not result in the predicted degradation in aircraft flying qualities. The impact of the feel system is discussed from two viewpoints: as a filter in the control system which can alter the initial response shape and, therefore, the allowable time delay, and as a unique dynamic element whose delay contribution can potentially be discounted by special pilot loop closures.

Describing-function analysis of a ripple regulator with slew-rate limits and time delays

NASA Technical Reports Server (NTRS)

Wester, Gene W.

1990-01-01

The effects of time delays and slew-rate limits on the steady-state operating points and performance of a free-running ripple regulator are evaluated using describing-function analysis. The describing function of an ideal comparator (no time delays or slew rate limits) has no phase shift and is independent of frequency. It is found that turn-on delay and turn-off delay have different effects on gain and phase and cannot be combined. Comparator hysteresis affects both gain and phase; likewise, time delays generally affect both gain and phase. It is found that the effective time delay around the feedback loop is one half the sum of turn-on and turn-off delays, regardless of whether the delays are caused by storage time or slew rate limits. Expressions are formulated for the switching frequency, switch duty ratio, dc output, and output ripple. For the case of no hysteresis, a simple, graphical solution for the switching frequency is possible, and the resulting switching frequency is independent of first-order variations of input or load.

Biocorrosion properties and blood and cell compatibility of pure iron as a biodegradable biomaterial.

PubMed

Zhang, Erlin; Chen, Haiyan; Shen, Feng

2010-07-01

Biocorrosion properties and blood- and cell compatibility of pure iron were studied in comparison with 316L stainless steel and Mg-Mn-Zn magnesium alloy to reveal the possibility of pure iron as a biodegradable biomaterial. Both electrochemical and weight loss tests showed that pure iron showed a relatively high corrosion rate at the first several days and then decreased to a low level during the following immersion due to the formation of phosphates on the surface. However, the corrosion of pure iron did not cause significant increase in pH value to the solution. In comparison with 316L and Mg-Mn-Zn alloy, the pure iron exhibited biodegradable property in a moderate corrosion rate. Pure iron possessed similar dynamic blood clotting time, prothrombin time and plasma recalcification time to 316L and Mg-Mn-Zn alloy, but a lower hemolysis ratio and a significant lower number density of adhered platelets. MTT results revealed that the extract except the one with 25% 24 h extract actually displayed toxicity to cells and the toxicity increased with the increasing of the iron ion concentration and the incubation time. It was thought there should be an iron ion concentration threshold in the effect of iron ion on the cell toxicity.

Market-based control strategy for long-span structures considering the multi-time delay issue

NASA Astrophysics Data System (ADS)

Li, Hongnan; Song, Jianzhu; Li, Gang

2017-01-01

To solve the different time delays that exist in the control device installed on spatial structures, in this study, discrete analysis using a 2 N precise algorithm was selected to solve the multi-time-delay issue for long-span structures based on the market-based control (MBC) method. The concept of interval mixed energy was introduced from computational structural mechanics and optimal control research areas, and it translates the design of the MBC multi-time-delay controller into a solution for the segment matrix. This approach transforms the serial algorithm in time to parallel computing in space, greatly improving the solving efficiency and numerical stability. The designed controller is able to consider the issue of time delay with a linear controlling force combination and is especially effective for large time-delay conditions. A numerical example of a long-span structure was selected to demonstrate the effectiveness of the presented controller, and the time delay was found to have a significant impact on the results.

Delay time and Hartman effect in strain engineered graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Xi, E-mail: xchen@shu.edu.cn; Deng, Zhi-Yong; Ban, Yue, E-mail: yban@shu.edu.cn

2014-05-07

Tunneling times, including group delay and dwell time, are studied for massless Dirac electrons transmitting through a one-dimensional barrier in strain-engineered graphene. The Hartman effect, the independence of group delay on barrier length, is induced by the strain effect, and associated with the transmission gap and the evanescent mode. The influence of barrier height/length and strain modulus/direction on the group delay is also discussed, which provides the flexibility to control the group delay with applications in graphene-based devices. The relationship between group delay and dwell time is finally derived to clarify the nature of the Hartman effect.

Reconstructions of parameters of radiophysical chaotic generator with delayed feedback from short time series

NASA Astrophysics Data System (ADS)

Ishbulatov, Yu. M.; Karavaev, A. S.; Kiselev, A. R.; Semyachkina-Glushkovskaya, O. V.; Postnov, D. E.; Bezruchko, B. P.

2018-04-01

A method for the reconstruction of time-delayed feedback system is investigated, which is based on the detection of synchronous response of a slave time-delay system with respect to the driving from the master system under study. The structure of the driven system is similar to the structure of the studied time-delay system, but the feedback circuit is broken in the driven system. The method efficiency is tested using short and noisy data gained from an electronic chaotic oscillator with time-delayed feedback.

Reconstruction of ensembles of coupled time-delay systems from time series.

PubMed

Sysoev, I V; Prokhorov, M D; Ponomarenko, V I; Bezruchko, B P

2014-06-01

We propose a method to recover from time series the parameters of coupled time-delay systems and the architecture of couplings between them. The method is based on a reconstruction of model delay-differential equations and estimation of statistical significance of couplings. It can be applied to networks composed of nonidentical nodes with an arbitrary number of unidirectional and bidirectional couplings. We test our method on chaotic and periodic time series produced by model equations of ensembles of diffusively coupled time-delay systems in the presence of noise, and apply it to experimental time series obtained from electronic oscillators with delayed feedback coupled by resistors.

Stability of Nonlinear Systems with Unknown Time-varying Feedback Delay

NASA Astrophysics Data System (ADS)

Chunodkar, Apurva A.; Akella, Maruthi R.

2013-12-01

This paper considers the problem of stabilizing a class of nonlinear systems with unknown bounded delayed feedback wherein the time-varying delay is 1) piecewise constant 2) continuous with a bounded rate. We also consider application of these results to the stabilization of rigid-body attitude dynamics. In the first case, the time-delay in feedback is modeled specifically as a switch among an arbitrarily large set of unknown constant values with a known strict upper bound. The feedback is a linear function of the delayed states. In the case of linear systems with switched delay feedback, a new sufficiency condition for average dwell time result is presented using a complete type Lyapunov-Krasovskii (L-K) functional approach. Further, the corresponding switched system with nonlinear perturbations is proven to be exponentially stable inside a well characterized region of attraction for an appropriately chosen average dwell time. In the second case, the concept of the complete type L-K functional is extended to a class of nonlinear time-delay systems with unknown time-varying time-delay. This extension ensures stability robustness to time-delay in the control design for all values of time-delay less than the known upper bound. Model-transformation is used in order to partition the nonlinear system into a nominal linear part that is exponentially stable with a bounded perturbation. We obtain sufficient conditions which ensure exponential stability inside a region of attraction estimate. A constructive method to evaluate the sufficient conditions is presented together with comparison with the corresponding constant and piecewise constant delay. Numerical simulations are performed to illustrate the theoretical results of this paper.

Effect of metrology time delay on overlay APC

NASA Astrophysics Data System (ADS)

Carlson, Alan; DiBiase, Debra

2002-07-01

The run-to-run control strategy of lithography APC is primarily composed of a feedback loop as shown in the diagram below. It is known that the insertion of a time delay in a feedback loop can cause degradation in control performance and could even cause a stable system to become unstable, if the time delay becomes sufficiently large. Many proponents of integrated metrology methods have cited the damage caused by metrology time delays as the primary justification for moving from a stand-alone to integrated metrology. While there is little dispute over the qualitative form of this argument, there has been very light published about the quantitative effects under real fab conditions - precisely how much control is lost due to these time delays. Another issue regarding time delays is that the length of these delays is not typically fixed - they vary from lot to lot and in some cases this variance can be large - from one hour on the short side to over 32 hours on the long side. Concern has been expressed that the variability in metrology time delays can cause undesirable dynamics in feedback loops that make it difficult to optimize feedback filters and gains and at worst could drive a system unstable. By using data from numerous fabs, spanning many sizes and styles of operation, we have conducted a quantitative study of the time delay effect on overlay run- to-run control. Our analysis resulted in the following conclusions: (1) There is a significant and material relationship between metrology time delay and overlay control under a variety of real world production conditions. (2) The run-to-run controller can be configured to minimize sensitivity to time delay variations. (3) The value of moving to integrated metrology can be quantified.

Opposite Effects of the Spinach Food Matrix on Lutein Bioaccessibility and Intestinal Uptake Lead to Unchanged Bioavailability Compared to Pure Lutein.

PubMed

Margier, Marielle; Buffière, Caroline; Goupy, Pascale; Remond, Didier; Halimi, Charlotte; Caris-Veyrat, Catherine; Borel, Patrick; Reboul, Emmanuelle

2018-06-01

Food matrix is generally believed to alter carotenoid bioavailability, but its effect on xanthophylls is usually limited. This study thus aims to decipher the digestion-absorption process of lutein in the presence or not of a food matrix. Lutein transfer to gastric-like lipid droplets or artificial mixed micelles was assessed when lutein was added to test meals either as a pure molecule ((all-E)-lutein) or in canned spinach ((Z) + (all-E)-lutein). The obtained mixed micelles were delivered to Caco-2 cells to evaluate lutein uptake. Finally postprandial plasma lutein responses were compared in minipigs after the two test meals. Lutein transfer to gastric-like lipid droplets and to mixed micelles was higher when lutein was added in spinach than when it was added as pure lutein (+614% and +147%, respectively, p < 0.05). Conversely, lutein uptake was less effective when micellar lutein was from a meal containing spinach than from a meal containing its pure form (-55%, p < 0.05). In minipigs, postprandial lutein response was delayed with spinach but not significantly different after the two test meals. Opposite effects at the micellarization and intestinal cell uptake steps explain the lack of effect of spinach matrix on lutein bioavailability. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

76 FR 59111 - Pure Magnesium From the People's Republic of China: Extension of Time for the Final Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-23

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-832] Pure Magnesium From the People's Republic of China: Extension of Time for the Final Results of the Antidumping Duty... administrative review for the period May 1, 2009, to April 30, 2010. See Pure Magnesium from the People's...

75 FR 63440 - Pure Magnesium From the People's Republic of China: Extension of Time for the Final Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-15

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-832] Pure Magnesium From the People's Republic of China: Extension of Time for the Final Results of the Antidumping Duty... of this administrative review for the period May 1, 2008, to April 30, 2009. See Pure Magnesium from...

Low phase noise microwave extraction from femtosecond laser by frequency conversion pair and IF-domain processing.

PubMed

Dai, Yitang; Cen, Qizhuang; Wang, Lei; Zhou, Yue; Yin, Feifei; Dai, Jian; Li, Jianqiang; Xu, Kun

2015-12-14

Extraction of a microwave component from a low-time-jitter femtosecond pulse train has been attractive for current generation of spectrally pure microwave. In order to avoid the transfer from the optical amplitude noise to microwave phase noise (AM-PM), we propose to down-convert the target component to intermediate frequency (IF) before the opto-electronic conversion. Due to the much lower carrier frequency, the AM-PM is greatly suppressed. The target is then recovered by up-conversion with the same microwave local oscillation (LO). As long as the time delay of the second LO matches that of the IF carrier, the phase noise of the LO shows no impact on the extraction process. The residual noise of the proposed extraction is analyzed in theory, which is also experimentally demonstrated as averagely around -155 dBc/Hz under offset frequency larger than 1 kHz when 10-GHz tone is extracted from a home-made femtosecond fiber laser. Large tunable extraction from 1 GHz to 10 GHz is also reported.

Digital time delay

DOEpatents

Martin, A.D.

1986-05-09

Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay provides a first output signal at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits latch the high resolution data to form a first synchronizing data set. A selected time interval has been preset to internal counters and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses count down the counters to generate an internal pulse delayed by an internal which is functionally related to the preset time interval. A second LCD corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD to generate a second set of synchronizing data which is complementary with the first set of synchronizing data for presentation to logic circuits. The logic circuits further delay the internal output signal with the internal pulses. The final delayed output signal thereafter enables the output pulse generator to produce the desired output pulse at the preset time delay interval following input of the trigger pulse.

Traversal of electromagnetic pulses through dispersive media with negative refractive index

NASA Astrophysics Data System (ADS)

Nanda, L.; Ramakrishna, S. A.

2017-05-01

We investigate the traversal of electromagnetic pulses through dispersive media with negative refractive index in such a way that no resonant effects come into play. It has been verified that for evanescent waves, the definitions of the group delay and the reshaping delay times get interchanged in comparison to the propagating waves. We show that for a negative refractive index medium (NRM) with ɛ(ω)=μ(ω), the reshaping delay time identically vanishes for propagating waves. The total delay time in NRM is otherwise contributed by both the group and the reshaping delay times, whereas for the case of broadband pulses in NRM the total delay time is always subluminal.

Simulation analysis of the effect of initial delay on flight delay diffusion

NASA Astrophysics Data System (ADS)

Que, Zufu; Yao, Hongguang; Yue, Wei

2018-01-01

The initial delay of the flight is an important factor affecting the spread of flight delays, so clarifying their relationship conduces to control flight delays in the aeronautical network. Through establishing a model of the chain aviation network and making simulation analysis of the effects of initial delay on the delay longitudinal diffusion, it’s found that the number of delayed airports in the air network, the total delay time and the average delay time of the delayed airport are generally positively correlated with the initial delay. This indicates that the occurrence of the initial delay should be avoided or reduced as much as possible to improve the punctuality of the flight.

Estimates of Zenith Total Delay trends from GPS reprocessing with autoregressive process

NASA Astrophysics Data System (ADS)

Klos, Anna; Hunegnaw, Addisu; Teferle, Felix Norman; Ebuy Abraha, Kibrom; Ahmed, Furqan; Bogusz, Janusz

2017-04-01

Nowadays, near real-time Zenith Total Delay (ZTD) estimates from Global Positioning System (GPS) observations are routinely assimilated into numerical weather prediction (NWP) models to improve the reliability of forecasts. On the other hand, ZTD time series derived from homogeneously re-processed GPS observations over long periods have the potential to improve our understanding of climate change on various temporal and spatial scales. With such time series only recently reaching somewhat adequate time spans, the application of GPS-derived ZTD estimates to climate monitoring is still to be developed further. In this research, we examine the character of noise in ZTD time series for 1995-2015 in order to estimate more realistic magnitudes of trend and its uncertainty than would be the case if the stochastic properties are not taken into account. Furthermore, the hourly sampled, homogeneously re-processed and carefully homogenized ZTD time series from over 700 globally distributed stations were classified into five major climate zones. We found that the amplitudes of annual signals reach values of 10-150 mm with minimum values for the polar and Alpine zones. The amplitudes of daily signals were estimated to be 0-12 mm with maximum values found for the dry zone. We examined seven different noise models for the residual ZTD time series after modelling all known periodicities. This identified a combination of white plus autoregressive process of fourth order to be optimal to match all changes in power of the ZTD data. When the stochastic properties are neglected, ie. a pure white noise model is employed, only 11 from 120 trends were insignificant. Using the optimum noise model more than half of the 120 examined trends became insignificant. We show that the uncertainty of ZTD trends is underestimated by a factor of 3-12 when the stochastic properties of the ZTD time series are ignored and we conclude that it is essential to properly model the noise characteristics of such time series when interpretations in terms of climate change are to be performed.

Phase holograms in PMMA with proximity effect correction

NASA Technical Reports Server (NTRS)

Maker, Paul D.; Muller, R. E.

1993-01-01

Complex computer generated phase holograms (CGPH's) have been fabricated in PMMA by partial e-beam exposure and subsequent partial development. The CGPH was encoded as a sequence of phase delay pixels and written by the JEOL JBX-5D2 E-beam lithography system, a different dose being assigned to each value of phase delay. Following carefully controlled partial development, the pattern appeared rendered in relief in the PMMA, which then acts as the phase-delay medium. The exposure dose was in the range 20-200 micro-C/sq cm, and very aggressive development in pure acetone led to low contrast. This enabled etch depth control to better than plus or minus lambda(sub vis)/60. That result was obtained by exposing isolated 50 micron square patches and measuring resist removal over the central area where the proximity effect dose was uniform and related only to the local exposure. For complex CGPH's with pixel size of the order of the e-beam proximity effect radius, the patterns must be corrected for the extra exposure caused by electrons scattered back up out of the substrate. This has been accomplished by deconvolving the two-dimensional dose deposition function with the desired dose pattern. The deposition function, which plays much the same role as an instrument response function, was carefully measured under the exact conditions used to expose the samples. The devices fabricated were designed with 16 equal phase steps per retardation cycle, were up to 1 cm square, and consisted of up to 100 million 0.3-2.0 micron square pixels. Data files were up to 500 MB long and exposure times ranged to tens of hours. A Fresnel phase lens was fabricated that had diffraction limited optical performance with better than 85 percent efficiency.

Estimation of coupling between time-delay systems from time series

NASA Astrophysics Data System (ADS)

Prokhorov, M. D.; Ponomarenko, V. I.

2005-07-01

We propose a method for estimation of coupling between the systems governed by scalar time-delay differential equations of the Mackey-Glass type from the observed time series data. The method allows one to detect the presence of certain types of linear coupling between two time-delay systems, to define the type, strength, and direction of coupling, and to recover the model equations of coupled time-delay systems from chaotic time series corrupted by noise. We verify our method using both numerical and experimental data.

LiDAR-IMU Time Delay Calibration Based on Iterative Closest Point and Iterated Sigma Point Kalman Filter

PubMed Central

Liu, Wanli

2017-01-01

The time delay calibration between Light Detection and Ranging (LiDAR) and Inertial Measurement Units (IMUs) is an essential prerequisite for its applications. However, the correspondences between LiDAR and IMU measurements are usually unknown, and thus cannot be computed directly for the time delay calibration. In order to solve the problem of LiDAR-IMU time delay calibration, this paper presents a fusion method based on iterative closest point (ICP) and iterated sigma point Kalman filter (ISPKF), which combines the advantages of ICP and ISPKF. The ICP algorithm can precisely determine the unknown transformation between LiDAR-IMU; and the ISPKF algorithm can optimally estimate the time delay calibration parameters. First of all, the coordinate transformation from the LiDAR frame to the IMU frame is realized. Second, the measurement model and time delay error model of LiDAR and IMU are established. Third, the methodology of the ICP and ISPKF procedure is presented for LiDAR-IMU time delay calibration. Experimental results are presented that validate the proposed method and demonstrate the time delay error can be accurately calibrated. PMID:28282897

What you feel is what you see: inverse dynamics estimation underlies the resistive sensation of a delayed cursor

PubMed Central

Takamuku, Shinya; Gomi, Hiroaki

2015-01-01

How our central nervous system (CNS) learns and exploits relationships between force and motion is a fundamental issue in computational neuroscience. While several lines of evidence have suggested that the CNS predicts motion states and signals from motor commands for control and perception (forward dynamics), it remains controversial whether it also performs the ‘inverse’ computation, i.e. the estimation of force from motion (inverse dynamics). Here, we show that the resistive sensation we experience while moving a delayed cursor, perceived purely from the change in visual motion, provides evidence of the inverse computation. To clearly specify the computational process underlying the sensation, we systematically varied the visual feedback and examined its effect on the strength of the sensation. In contrast to the prevailing theory that sensory prediction errors modulate our perception, the sensation did not correlate with errors in cursor motion due to the delay. Instead, it correlated with the amount of exposure to the forward acceleration of the cursor. This indicates that the delayed cursor is interpreted as a mechanical load, and the sensation represents its visually implied reaction force. Namely, the CNS automatically computes inverse dynamics, using visually detected motions, to monitor the dynamic forces involved in our actions. PMID:26156766

[Time perception in depressed and manic patients].

PubMed

Zhao, Qi-yuan; Ji, Yi-fu; Wang, Kai; Zhang, Lei; Liu, Ping; Jiang, Yu-bao

2010-02-02

To investigate the time perception in affective disorders by using neuropsychological tests and to try to elucidate its neurobiochemical mechanism. Using a time reproduction task, a comparative study was conducted for 28 depressive patients, 22 manic patients, and 26 age and education level matched healthy persons as healthy controls. Both depressive patients and manic patients are abnormal (P < 0.001), depressive patients over-reproduced the time interval than healthy controls (600 ms/delay 1 s: 1.6 +/- 0.6, P < 0.001; 600 ms/delay 5 s: 1.7 +/- 0.6, P < 0.001; 3 s/delay 1 s: 3.9 +/- 0.9, P < 0.001; 3 s/delay 5 s: 3.9 +/- 0.7, P < 0.001; 5 s/delay 1 s: 5.9 +/- 1.3, P < 0.001; 5 s/delay 5 s: 6.1 +/- 1.3, P < 0.001), yet manic patients under-reproduced the time interval (600 ms/delay 1 s: 0.7 +/- 0.2, P < 0.01; 600 ms/delay 5 s: 0.6 +/- 0.3, P < 0.001; 3 s/delay 1 s: 1.7 +/- 0.5, P < 0.001; 3 s/delay 5 s: 1.8 +/- 0.6, P < 0.001; 5 s/delay 1 s: 2.9 +/- 0.7, P < 0.001; 5 s/delay 5 s: 3.0 +/- 0.8, P < 0.001). The results of time reproduction task in patients were not related to age, education, duration of illness, number of admission (P > 0.05), but had some relation to severity of illness.And the results were positively correlated with the score of HAMD in depressive patients (six times: r = 0.44, 0.46, 0.73, 0.61, 0.55, 0.50, P < 0.05), but negatively with the score of BRMS in manic patients (six times: r = -0.57, -0.54, -0.71, -0.69, -0.80, -0.71, P < 0.05). Emotion will affect one's time perception. And the neurotransmitter in brain may participate in the processes of time perception.

Bounded Linear Stability Analysis - A Time Delay Margin Estimation Approach for Adaptive Control

NASA Technical Reports Server (NTRS)

Nguyen, Nhan T.; Ishihara, Abraham K.; Krishnakumar, Kalmanje Srinlvas; Bakhtiari-Nejad, Maryam

2009-01-01

This paper presents a method for estimating time delay margin for model-reference adaptive control of systems with almost linear structured uncertainty. The bounded linear stability analysis method seeks to represent the conventional model-reference adaptive law by a locally bounded linear approximation within a small time window using the comparison lemma. The locally bounded linear approximation of the combined adaptive system is cast in a form of an input-time-delay differential equation over a small time window. The time delay margin of this system represents a local stability measure and is computed analytically by a matrix measure method, which provides a simple analytical technique for estimating an upper bound of time delay margin. Based on simulation results for a scalar model-reference adaptive control system, both the bounded linear stability method and the matrix measure method are seen to provide a reasonably accurate and yet not too conservative time delay margin estimation.

Broadband true time delay for microwave signal processing, using slow light based on stimulated Brillouin scattering in optical fibers.

PubMed

Chin, Sanghoon; Thévenaz, Luc; Sancho, Juan; Sales, Salvador; Capmany, José; Berger, Perrine; Bourderionnet, Jérôme; Dolfi, Daniel

2010-10-11

We experimentally demonstrate a novel technique to process broadband microwave signals, using all-optically tunable true time delay in optical fibers. The configuration to achieve true time delay basically consists of two main stages: photonic RF phase shifter and slow light, based on stimulated Brillouin scattering in fibers. Dispersion properties of fibers are controlled, separately at optical carrier frequency and in the vicinity of microwave signal bandwidth. This way time delay induced within the signal bandwidth can be manipulated to correctly act as true time delay with a proper phase compensation introduced to the optical carrier. We completely analyzed the generated true time delay as a promising solution to feed phased array antenna for radar systems and to develop dynamically reconfigurable microwave photonic filters.

Finite-Time Stabilization and Adaptive Control of Memristor-Based Delayed Neural Networks.

PubMed

Wang, Leimin; Shen, Yi; Zhang, Guodong

Finite-time stability problem has been a hot topic in control and system engineering. This paper deals with the finite-time stabilization issue of memristor-based delayed neural networks (MDNNs) via two control approaches. First, in order to realize the stabilization of MDNNs in finite time, a delayed state feedback controller is proposed. Then, a novel adaptive strategy is applied to the delayed controller, and finite-time stabilization of MDNNs can also be achieved by using the adaptive control law. Some easily verified algebraic criteria are derived to ensure the stabilization of MDNNs in finite time, and the estimation of the settling time functional is given. Moreover, several finite-time stability results as our special cases for both memristor-based neural networks (MNNs) without delays and neural networks are given. Finally, three examples are provided for the illustration of the theoretical results.Finite-time stability problem has been a hot topic in control and system engineering. This paper deals with the finite-time stabilization issue of memristor-based delayed neural networks (MDNNs) via two control approaches. First, in order to realize the stabilization of MDNNs in finite time, a delayed state feedback controller is proposed. Then, a novel adaptive strategy is applied to the delayed controller, and finite-time stabilization of MDNNs can also be achieved by using the adaptive control law. Some easily verified algebraic criteria are derived to ensure the stabilization of MDNNs in finite time, and the estimation of the settling time functional is given. Moreover, several finite-time stability results as our special cases for both memristor-based neural networks (MNNs) without delays and neural networks are given. Finally, three examples are provided for the illustration of the theoretical results.

The effect of visual-motion time delays on pilot performance in a pursuit tracking task

NASA Technical Reports Server (NTRS)

Miller, G. K., Jr.; Riley, D. R.

1976-01-01

A study has been made to determine the effect of visual-motion time delays on pilot performance of a simulated pursuit tracking task. Three interrelated major effects have been identified: task difficulty, motion cues, and time delays. As task difficulty, as determined by airplane handling qualities or target frequency, increases, the amount of acceptable time delay decreases. However, when relatively complete motion cues are included in the simulation, the pilot can maintain his performance for considerably longer time delays. In addition, the number of degrees of freedom of motion employed is a significant factor.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dustin Popp; Zander Mausolff; Sedat Goluoglu

We are proposing to use the code, TDKENO, to model TREAT. TDKENO solves the time dependent, three dimensional Boltzmann transport equation with explicit representation of delayed neutrons. Instead of directly integrating this equation, the neutron flux is factored into two components – a rapidly varying amplitude equation and a slowly varying shape equation and each is solved separately on different time scales. The shape equation is solved using the 3D Monte Carlo transport code KENO, from Oak Ridge National Laboratory’s SCALE code package. Using the Monte Carlo method to solve the shape equation is still computationally intensive, but the operationmore » is only performed when needed. The amplitude equation is solved deterministically and frequently, so the solution gives an accurate time-dependent solution without having to repeatedly We have modified TDKENO to incorporate KENO-VI so that we may accurately represent the geometries within TREAT. This paper explains the motivation behind using generalized geometry, and provides the results of our modifications. TDKENO uses the Improved Quasi-Static method to accomplish this. In this method, the neutron flux is factored into two components. One component is a purely time-dependent and rapidly varying amplitude function, which is solved deterministically and very frequently (small time steps). The other is a slowly varying flux shape function that weakly depends on time and is only solved when needed (significantly larger time steps).« less

How Does the Linguistic Distance Between Spoken and Standard Language in Arabic Affect Recall and Recognition Performances During Verbal Memory Examination.

PubMed

Taha, Haitham

2017-06-01

The current research examined how Arabic diglossia affects verbal learning memory. Thirty native Arab college students were tested using auditory verbal memory test that was adapted according to the Rey Auditory Verbal Learning Test and developed in three versions: Pure spoken language version (SL), pure standard language version (SA), and phonologically similar version (PS). The result showed that for immediate free-recall, the performances were better for the SL and the PS conditions compared to the SA one. However, for the parts of delayed recall and recognition, the results did not reveal any significant consistent effect of diglossia. Accordingly, it was suggested that diglossia has a significant effect on the storage and short term memory functions but not on long term memory functions. The results were discussed in light of different approaches in the field of bilingual memory.

Robust stability bounds for multi-delay networked control systems

NASA Astrophysics Data System (ADS)

Seitz, Timothy; Yedavalli, Rama K.; Behbahani, Alireza

2018-04-01

In this paper, the robust stability of a perturbed linear continuous-time system is examined when controlled using a sampled-data networked control system (NCS) framework. Three new robust stability bounds on the time-invariant perturbations to the original continuous-time plant matrix are presented guaranteeing stability for the corresponding discrete closed-loop augmented delay-free system (ADFS) with multiple time-varying sensor and actuator delays. The bounds are differentiated from previous work by accounting for the sampled-data nature of the NCS and for separate communication delays for each sensor and actuator, not a single delay. Therefore, this paper expands the knowledge base in multiple inputs multiple outputs (MIMO) sampled-data time delay systems. Bounds are presented for unstructured, semi-structured, and structured perturbations.

Alleviation of whirl-flutter on a joined-wing tilt-rotor aircraft configuration using active controls

NASA Technical Reports Server (NTRS)

Vanaken, Johannes M.

1991-01-01

The feasibility of using active controls to delay the onset of whirl-flutter on a joined-wing tilt rotor aircraft was investigated. The CAMRAD/JA code was used to obtain a set of linear differential equations which describe the motion of the joined-wing tilt-rotor aircraft. The hub motions due to wing/body motion is a standard input to CAMRAD/JA and were obtained from a structural dynamics model of a representative joined-wing tilt-rotor aircraft. The CAMRAD/JA output, consisting of the open-loop system matrices, and the airframe free vibration motion were input to a separate program which performed the closed-loop, active control calculations. An eigenvalue analysis was performed to determine the flutter stability of both open- and closed-loop systems. Sensor models, based upon the feedback of pure state variables and based upon hub-mounted sensors, providing physically measurable accelerations, were evaluated. It was shown that the onset of tilt-rotor whirl-flutter could be delayed from 240 to above 270 knots by feeding back vertical and span-wise accelerations, measured at the rotor hub, to the longitudinal cyclic pitch. Time response calculations at a 270-knot cruise condition showed an active cyclic pitch control level of 0.009 deg, which equates to a very acceptable 9 pound active-control force applied at the rotor hub.

Electrophysiology reveals semantic priming at a short SOA irrespective of depth of prime processing.

PubMed

Küper, Kristina; Heil, Martin

2009-04-03

The otherwise robust behavioral semantic priming effect is reduced to the point of being absent when a letter search has to be performed on the prime word. As a result the automaticity of semantic activation has been called into question. It is unclear, however, in how far automatic processes are even measurable in the letter search priming paradigm as the prime task necessitates a long prime-probe stimulus-onset asynchrony (SOA). In a modified procedure, a short SOA can be realized by delaying the prime task response until after participants have made a lexical decision on the probe. While the absence of lexical decision priming has already been demonstrated in this design it seems premature to draw any definite conclusions from this purely behavioral result since event related potential (ERP) measures have been shown to be a more sensitive index of semantic activation. Using the modified paradigm we thus recorded ERP in addition to lexical decision times. Stimuli were presented at two different SOAs (240 ms vs. 840 ms) and participants performed either a grammatical discrimination (Experiment 1) or a letter search (Experiment 2) on the prime. Irrespective of prime task, the modulation of the N400, the ERP correlate of semantic activation, provided clear-cut evidence of semantic processing at the short SOA. Implications for theories of semantic activation as well as the constraints of the delayed prime task procedure are discussed.

Discrete-time BAM neural networks with variable delays

NASA Astrophysics Data System (ADS)

Liu, Xin-Ge; Tang, Mei-Lan; Martin, Ralph; Liu, Xin-Bi

2007-07-01

This Letter deals with the global exponential stability of discrete-time bidirectional associative memory (BAM) neural networks with variable delays. Using a Lyapunov functional, and linear matrix inequality techniques (LMI), we derive a new delay-dependent exponential stability criterion for BAM neural networks with variable delays. As this criterion has no extra constraints on the variable delay functions, it can be applied to quite general BAM neural networks with a broad range of time delay functions. It is also easy to use in practice. An example is provided to illustrate the theoretical development.

Local Bifurcations and Optimal Theory in a Delayed Predator-Prey Model with Threshold Prey Harvesting

NASA Astrophysics Data System (ADS)

Tankam, Israel; Tchinda Mouofo, Plaire; Mendy, Abdoulaye; Lam, Mountaga; Tewa, Jean Jules; Bowong, Samuel

2015-06-01

We investigate the effects of time delay and piecewise-linear threshold policy harvesting for a delayed predator-prey model. It is the first time that Holling response function of type III and the present threshold policy harvesting are associated with time delay. The trajectories of our delayed system are bounded; the stability of each equilibrium is analyzed with and without delay; there are local bifurcations as saddle-node bifurcation and Hopf bifurcation; optimal harvesting is also investigated. Numerical simulations are provided in order to illustrate each result.

A Strain-Sonde Technique for the Measurement of Mechanical Time-Delay Fuze Function Times and Performance

DTIC Science & Technology

1983-09-01

AD IV) MEMORANDUM REPORT ARBRL-MR-03309 N(Supersedes IMR No. 760) A STRAIN -SONDE TECHNIQUE FOR THE MEASUREMENT OF MECHANICAL TIME- DELAY FUZE...and BkuWel) S. TYPE OF REPORT & PERIOD COVERED A STRAIN -SONDE TECHNIQUE FOR THE MEASUREMENT OF Final MECHANICAL TIME-DELAY FUZE FUNCTION TIMES AND S...nmber) M577 Mechanical Time-Delay Fuze F"/FM Telemeter Interlock Pin Release Semiconductor Strain Gage Rotor Signal Condition Amplifier Firing Pin In

Breast abscess as the initial manifestation of primary pure squamous cell carcinoma: a rare presentation and literature review.

PubMed

Salemis, Nikolaos S

2011-01-01

Primary squamous cell carcinoma of the breast is a very rare tumor accounting for less than 0.4% of all breast cancers. Fewer than 100 cases have been reported in the literature so far. The diagnosis requires strict pathologic criteria to be fulfilled. Due to the rarity of this tumor the optimal treatment and prognosis are both unclear. Breast abscess as the initial presentation of a primary squamous cell breast carcinoma is an extremely rare clinical entity. In this study, we describe a case of a 61-year-old postmenopausal woman who presented with typical manifestations of a breast abscess and was diagnosed with a pure primary squamous cell breast carcinoma. Diagnostic evaluation and management of the patient are discussed along with a review of the literature. Despite its rarity, the possibility of a primary pure squamous cell breast carcinoma should always be considered in the differential diagnosis in postmenopausal patients presenting with manifestations of a breast abscess, especially in those who respond poorly to the initial treatment. Physicians should be aware of this rare malignancy in order to avoid delays in diagnosis and treatment.

Robust optimization for nonlinear time-delay dynamical system of dha regulon with cost sensitivity constraint in batch culture

NASA Astrophysics Data System (ADS)

Yuan, Jinlong; Zhang, Xu; Liu, Chongyang; Chang, Liang; Xie, Jun; Feng, Enmin; Yin, Hongchao; Xiu, Zhilong

2016-09-01

Time-delay dynamical systems, which depend on both the current state of the system and the state at delayed times, have been an active area of research in many real-world applications. In this paper, we consider a nonlinear time-delay dynamical system of dha-regulonwith unknown time-delays in batch culture of glycerol bioconversion to 1,3-propanediol induced by Klebsiella pneumonia. Some important properties and strong positive invariance are discussed. Because of the difficulty in accurately measuring the concentrations of intracellular substances and the absence of equilibrium points for the time-delay system, a quantitative biological robustness for the concentrations of intracellular substances is defined by penalizing a weighted sum of the expectation and variance of the relative deviation between system outputs before and after the time-delays are perturbed. Our goal is to determine optimal values of the time-delays. To this end, we formulate an optimization problem in which the time delays are decision variables and the cost function is to minimize the biological robustness. This optimization problem is subject to the time-delay system, parameter constraints, continuous state inequality constraints for ensuring that the concentrations of extracellular and intracellular substances lie within specified limits, a quality constraint to reflect operational requirements and a cost sensitivity constraint for ensuring that an acceptable level of the system performance is achieved. It is approximated as a sequence of nonlinear programming sub-problems through the application of constraint transcription and local smoothing approximation techniques. Due to the highly complex nature of this optimization problem, the computational cost is high. Thus, a parallel algorithm is proposed to solve these nonlinear programming sub-problems based on the filled function method. Finally, it is observed that the obtained optimal estimates for the time-delays are highly satisfactory via numerical simulations.

Time delay and noise explaining the behaviour of the cell growth in fermentation process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayuobi, Tawfiqullah; Rosli, Norhayati; Bahar, Arifah

2015-02-03

This paper proposes to investigate the interplay between time delay and external noise in explaining the behaviour of the microbial growth in batch fermentation process. Time delay and noise are modelled jointly via stochastic delay differential equations (SDDEs). The typical behaviour of cell concentration in batch fermentation process under this model is investigated. Milstein scheme is applied for solving this model numerically. Simulation results illustrate the effects of time delay and external noise in explaining the lag and stationary phases, respectively for the cell growth of fermentation process.

Time delay and noise explaining the behaviour of the cell growth in fermentation process

NASA Astrophysics Data System (ADS)

Ayuobi, Tawfiqullah; Rosli, Norhayati; Bahar, Arifah; Salleh, Madihah Md

2015-02-01

This paper proposes to investigate the interplay between time delay and external noise in explaining the behaviour of the microbial growth in batch fermentation process. Time delay and noise are modelled jointly via stochastic delay differential equations (SDDEs). The typical behaviour of cell concentration in batch fermentation process under this model is investigated. Milstein scheme is applied for solving this model numerically. Simulation results illustrate the effects of time delay and external noise in explaining the lag and stationary phases, respectively for the cell growth of fermentation process.

The Effects of Financial Education on Impulsive Decision Making

PubMed Central

DeHart, William B.; Friedel, Jonathan E.; Lown, Jean M.; Odum, Amy L.

2016-01-01

Delay discounting, as a behavioral measure of impulsive choice, is strongly related to substance abuse and other risky behaviors. Therefore, effective techniques that alter delay discounting are of great interest. We explored the ability of a semester long financial education course to change delay discounting. Participants were recruited from a financial education course (n = 237) and an abnormal psychology course (n = 80). Both groups completed a delay-discounting task for $100 during the first two weeks (Time 1) of the semester as well as during the last two weeks (Time 2) of the semester. Participants also completed a personality inventory and financial risk tolerance scale both times and a delay-discounting task for $1,000 during Time 2. Delay discounting decreased in the financial education group at the end of the semester whereas there was no change in delay discounting in the abnormal psychology group. Financial education may be an effective method for reducing delay discounting. PMID:27442237

The Effects of Financial Education on Impulsive Decision Making.

PubMed

DeHart, William B; Friedel, Jonathan E; Lown, Jean M; Odum, Amy L

2016-01-01

Delay discounting, as a behavioral measure of impulsive choice, is strongly related to substance abuse and other risky behaviors. Therefore, effective techniques that alter delay discounting are of great interest. We explored the ability of a semester long financial education course to change delay discounting. Participants were recruited from a financial education course (n = 237) and an abnormal psychology course (n = 80). Both groups completed a delay-discounting task for $100 during the first two weeks (Time 1) of the semester as well as during the last two weeks (Time 2) of the semester. Participants also completed a personality inventory and financial risk tolerance scale both times and a delay-discounting task for $1,000 during Time 2. Delay discounting decreased in the financial education group at the end of the semester whereas there was no change in delay discounting in the abnormal psychology group. Financial education may be an effective method for reducing delay discounting.

Delay-induced stochastic bifurcations in a bistable system under white noise

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Zhongkui, E-mail: sunzk@nwpu.edu.cn; Fu, Jin; Xu, Wei

2015-08-15

In this paper, the effects of noise and time delay on stochastic bifurcations are investigated theoretically and numerically in a time-delayed Duffing-Van der Pol oscillator subjected to white noise. Due to the time delay, the random response is not Markovian. Thereby, approximate methods have been adopted to obtain the Fokker-Planck-Kolmogorov equation and the stationary probability density function for amplitude of the response. Based on the knowledge that stochastic bifurcation is characterized by the qualitative properties of the steady-state probability distribution, it is found that time delay and feedback intensity as well as noise intensity will induce the appearance of stochasticmore » P-bifurcation. Besides, results demonstrated that the effects of the strength of the delayed displacement feedback on stochastic bifurcation are accompanied by the sensitive dependence on time delay. Furthermore, the results from numerical simulations best confirm the effectiveness of the theoretical analyses.« less

The rates and time-delay distribution of multiply imaged supernovae behind lensing clusters

NASA Astrophysics Data System (ADS)

Li, Xue; Hjorth, Jens; Richard, Johan

2012-11-01

Time delays of gravitationally lensed sources can be used to constrain the mass model of a deflector and determine cosmological parameters. We here present an analysis of the time-delay distribution of multiply imaged sources behind 17 strong lensing galaxy clusters with well-calibrated mass models. We find that for time delays less than 1000 days, at z = 3.0, their logarithmic probability distribution functions are well represented by P(log Δt) = 5.3 × 10-4Δttilde beta/M2502tilde beta, with tilde beta = 0.77, where M250 is the projected cluster mass inside 250 kpc (in 1014M⊙), and tilde beta is the power-law slope of the distribution. The resultant probability distribution function enables us to estimate the time-delay distribution in a lensing cluster of known mass. For a cluster with M250 = 2 × 1014M⊙, the fraction of time delays less than 1000 days is approximately 3%. Taking Abell 1689 as an example, its dark halo and brightest galaxies, with central velocity dispersions σ>=500kms-1, mainly produce large time delays, while galaxy-scale mass clumps are responsible for generating smaller time delays. We estimate the probability of observing multiple images of a supernova in the known images of Abell 1689. A two-component model of estimating the supernova rate is applied in this work. For a magnitude threshold of mAB = 26.5, the yearly rate of Type Ia (core-collapse) supernovae with time delays less than 1000 days is 0.004±0.002 (0.029±0.001). If the magnitude threshold is lowered to mAB ~ 27.0, the rate of core-collapse supernovae suitable for time delay observation is 0.044±0.015 per year.

Elapsed Time Between the First Symptoms of Breast Cancer and Medical Help-Seeking Behavior and the Affecting Factors.

PubMed

Gözüm, Sebahat; Tuzcu, Ayla

Many studies have determined that the time between women's realization of first symptoms and seeking help from a healthcare professional is more than 1 month. The situation is defined as delay in medical help-seeking behavior (MHSB). The purpose of this study was to determine the time elapsed between the first symptoms of breast cancer and MHSB, as well as the factors contributing to the delay. In this descriptive study, the data were collected from 132 patients who received a diagnosis of breast cancer and are receiving treatment in the Oncology Clinic of Akdeniz University Hospital. The questionnaire used in the study was structured in 3 parts: sociodemographic characteristics, breast cancer history/screening behaviors, and psychological factors affecting MHSB. The elapsed time between patients' first symptoms and MHSB was classified into "normal" when it was less than 1 month, "delay" when it was between 1 and 3 months, "long-term delay" when it was more than 3 months, and "very serious delay" when it was more than 6 months. A total of 59.8% were classified as normal, 16.7% as delayed, 5.3% as a long-term delay, and 18.2% as a very serious delay after first symptoms. The delay in MHSB time was affected 18.55 times by "not caring/minding," 10.73 times by "fear," 7.13 times by "having more important problems," and 4.23 times by "realization of first symptoms" by themselves. Psychological factors were the most important determinants in delay. The MHSB time was less if those first realizing the symptoms were healthcare professionals. Healthcare professionals should direct women to screenings and train them to interpret symptoms correctly.

Self-esteem in pure bullies and bully/victims: a longitudinal analysis.

PubMed

Pollastri, Alisha R; Cardemil, Esteban V; O'Donnell, Ellen H

2010-08-01

Past research on the self-esteem of bullies has produced equivocal results. Recent studies have suggested that the inconsistent findings may be due, in part, to the failure to account for bully/victims: those children who both bully and are victims of bullying. In this longitudinal study, we examined the distinctions among pure bullies, pure victims, bully/victims, and noninvolved children in a sample of 307 middle school students. Analyses of cross-sectional and longitudinal results supported the importance of distinguishing between pure bullies and bully/victims. In addition, results revealed some interesting sex differences: girls in the pure bully and bully/victim groups reported significant increases in self-esteem over time, with girls in the pure bully group reporting the greatest increase, whereas boys in these groups reported no significant changes in self-esteem over time.

Effects of computing time delay on real-time control systems

NASA Technical Reports Server (NTRS)

Shin, Kang G.; Cui, Xianzhong

1988-01-01

The reliability of a real-time digital control system depends not only on the reliability of the hardware and software used, but also on the speed in executing control algorithms. The latter is due to the negative effects of computing time delay on control system performance. For a given sampling interval, the effects of computing time delay are classified into the delay problem and the loss problem. Analysis of these two problems is presented as a means of evaluating real-time control systems. As an example, both the self-tuning predicted (STP) control and Proportional-Integral-Derivative (PID) control are applied to the problem of tracking robot trajectories, and their respective effects of computing time delay on control performance are comparatively evaluated. For this example, the STP (PID) controller is shown to outperform the PID (STP) controller in coping with the delay (loss) problem.

The influences of delay time on the stability of a market model with stochastic volatility

NASA Astrophysics Data System (ADS)

Li, Jiang-Cheng; Mei, Dong-Cheng

2013-02-01

The effects of the delay time on the stability of a market model are investigated, by using a modified Heston model with a cubic nonlinearity and cross-correlated noise sources. These results indicate that: (i) There is an optimal delay time τo which maximally enhances the stability of the stock price under strong demand elasticity of stock price, and maximally reduces the stability of the stock price under weak demand elasticity of stock price; (ii) The cross correlation coefficient of noises and the delay time play an opposite role on the stability for the case of the delay time <τo and the same role for the case of the delay time >τo. Moreover, the probability density function of the escape time of stock price returns, the probability density function of the returns and the correlation function of the returns are compared with other literatures.

Time delay and long-range connection induced synchronization transitions in Newman-Watts small-world neuronal networks.

PubMed

Qian, Yu

2014-01-01

The synchronization transitions in Newman-Watts small-world neuronal networks (SWNNs) induced by time delay τ and long-range connection (LRC) probability P have been investigated by synchronization parameter and space-time plots. Four distinct parameter regions, that is, asynchronous region, transition region, synchronous region, and oscillatory region have been discovered at certain LRC probability P = 1.0 as time delay is increased. Interestingly, desynchronization is observed in oscillatory region. More importantly, we consider the spatiotemporal patterns obtained in delayed Newman-Watts SWNNs are the competition results between long-range drivings (LRDs) and neighboring interactions. In addition, for moderate time delay, the synchronization of neuronal network can be enhanced remarkably by increasing LRC probability. Furthermore, lag synchronization has been found between weak synchronization and complete synchronization as LRC probability P is a little less than 1.0. Finally, the two necessary conditions, moderate time delay and large numbers of LRCs, are exposed explicitly for synchronization in delayed Newman-Watts SWNNs.

Time Delay and Long-Range Connection Induced Synchronization Transitions in Newman-Watts Small-World Neuronal Networks

PubMed Central

Qian, Yu

2014-01-01

The synchronization transitions in Newman-Watts small-world neuronal networks (SWNNs) induced by time delay and long-range connection (LRC) probability have been investigated by synchronization parameter and space-time plots. Four distinct parameter regions, that is, asynchronous region, transition region, synchronous region, and oscillatory region have been discovered at certain LRC probability as time delay is increased. Interestingly, desynchronization is observed in oscillatory region. More importantly, we consider the spatiotemporal patterns obtained in delayed Newman-Watts SWNNs are the competition results between long-range drivings (LRDs) and neighboring interactions. In addition, for moderate time delay, the synchronization of neuronal network can be enhanced remarkably by increasing LRC probability. Furthermore, lag synchronization has been found between weak synchronization and complete synchronization as LRC probability is a little less than 1.0. Finally, the two necessary conditions, moderate time delay and large numbers of LRCs, are exposed explicitly for synchronization in delayed Newman-Watts SWNNs. PMID:24810595

[Analysis of characteristics and influence factors of diagnostic delay of endometriosis].

PubMed

Han, X T; Guo, H Y; Kong, D L; Han, J S; Zhang, L F

2018-02-25

Objective: To access the influence factors of diagnostic delay of endometriosis. Methods: We designed a questionnaire of diagnostic delay of endometriosis. From February 2014 to February 2016, 400 patients who had dysmenorrhea and diagnosed with endometriosis by surgery in Peking University Third Hospital were surveyed retrospectively. Time and risk factors of diagnostic delay were analyzed. Results: The diagnostic delay of 400 patients was 13.0 years (0.2-43.0 years), 78.5%(314/400) patients thought pain was a normal phenomenon and didn't see the doctor. Patients who suffered dysmenorrhea at menarche experienced longer diagnostic delay than those who had dysmenorrhea after menarche (18.0 vs 4.5 years; Z= 191.800, P< 0.01) . Patients who suffered aggravating dysmenorrhea experienced shorter delay time than those who suffered stable or relieving dysmenorrhea (11.0 vs 12.5 vs 18.0 years; Z= 8.270, P< 0.05) , with the difference statistically significant, single factor analysis shows. Severe dysmenorrhea, deep infiltration endometriosis (DIE) , family history of dysmenorrhea or endometriosis, previous surgical history of endometriosis, high stage, with infertility, adenomyoma or other symptoms, could help to shorten diagnostic delay with no significant difference ( P> 0.05) . By multiple logistic regression analysis, the results shown that whether have dysmenorrhea at menarche and clinical diagnosis time were the independent factors affecting delayed diagnosis ( P< 0.01) . Conclusions: Diagnostic delay of endometriosis is common and the mean delay time is 13.0 years mainly due to the unawareness of dysmenorrhea. Dysmenorrhea at menarche, clinical diagnosis time and dysmenorrhea intensity are the factors affecting time of diagnostic delay.

LMI designmethod for networked-based PID control

NASA Astrophysics Data System (ADS)

Souza, Fernando de Oliveira; Mozelli, Leonardo Amaral; de Oliveira, Maurício Carvalho; Palhares, Reinaldo Martinez

2016-10-01

In this paper, we propose a methodology for the design of networked PID controllers for second-order delayed processes using linear matrix inequalities. The proposed procedure takes into account time-varying delay on the plant, time-varying delays induced by the network and packed dropouts. The design is carried on entirely using a continuous-time model of the closed-loop system where time-varying delays are used to represent sampling and holding occurring in a discrete-time digital PID controller.

Accurate time delay technology in simulated test for high precision laser range finder

NASA Astrophysics Data System (ADS)

Chen, Zhibin; Xiao, Wenjian; Wang, Weiming; Xue, Mingxi

2015-10-01

With the continuous development of technology, the ranging accuracy of pulsed laser range finder (LRF) is higher and higher, so the maintenance demand of LRF is also rising. According to the dominant ideology of "time analog spatial distance" in simulated test for pulsed range finder, the key of distance simulation precision lies in the adjustable time delay. By analyzing and comparing the advantages and disadvantages of fiber and circuit delay, a method was proposed to improve the accuracy of the circuit delay without increasing the count frequency of the circuit. A high precision controllable delay circuit was designed by combining the internal delay circuit and external delay circuit which could compensate the delay error in real time. And then the circuit delay accuracy could be increased. The accuracy of the novel circuit delay methods proposed in this paper was actually measured by a high sampling rate oscilloscope actual measurement. The measurement result shows that the accuracy of the distance simulated by the circuit delay is increased from +/- 0.75m up to +/- 0.15m. The accuracy of the simulated distance is greatly improved in simulated test for high precision pulsed range finder.

Kalman filters for fractional discrete-time stochastic systems along with time-delay in the observation signal

NASA Astrophysics Data System (ADS)

Torabi, H.; Pariz, N.; Karimpour, A.

2016-02-01

This paper investigates fractional Kalman filters when time-delay is entered in the observation signal in the discrete-time stochastic fractional order state-space representation. After investigating the common fractional Kalman filter, we try to derive a fractional Kalman filter for time-delay fractional systems. A detailed derivation is given. Fractional Kalman filters will be used to estimate recursively the states of fractional order state-space systems based on minimizing the cost function when there is a constant time delay (d) in the observation signal. The problem will be solved by converting the filtering problem to a usual d-step prediction problem for delay-free fractional systems.

Time Delay of CGM Sensors

PubMed Central

Schmelzeisen-Redeker, Günther; Schoemaker, Michael; Kirchsteiger, Harald; Freckmann, Guido; Heinemann, Lutz; del Re, Luigi

2015-01-01

Background: Continuous glucose monitoring (CGM) is a powerful tool to support the optimization of glucose control of patients with diabetes. However, CGM systems measure glucose in interstitial fluid but not in blood. Rapid changes in one compartment are not accompanied by similar changes in the other, but follow with some delay. Such time delays hamper detection of, for example, hypoglycemic events. Our aim is to discuss the causes and extent of time delays and approaches to compensate for these. Methods: CGM data were obtained in a clinical study with 37 patients with a prototype glucose sensor. The study was divided into 5 phases over 2 years. In all, 8 patients participated in 2 phases separated by 8 months. A total number of 108 CGM data sets including raw signals were used for data analysis and were processed by statistical methods to obtain estimates of the time delay. Results: Overall mean (SD) time delay of the raw signals with respect to blood glucose was 9.5 (3.7) min, median was 9 min (interquartile range 4 min). Analysis of time delays observed in the same patients separated by 8 months suggests a patient dependent delay. No significant correlation was observed between delay and anamnestic or anthropometric data. The use of a prediction algorithm reduced the delay by 4 minutes on average. Conclusions: Prediction algorithms should be used to provide real-time CGM readings more consistent with simultaneous measurements by SMBG. Patient specificity may play an important role in improving prediction quality. PMID:26243773

A comparison of control modes for time-delayed remote manipulation

NASA Technical Reports Server (NTRS)

Starr, G. P.

1982-01-01

Transmission time delay in the communication channel of a manual control system is investigated. A time delay can exist in remote manipulation systems, caused by long communication distances or bandwidth limitations. Ferrell 1 conducted the first research in time-delayed manipulation using a two degree-of-freedom manipulator. His subjects, working at time delays of 1.0, 2.1, and 3.2 s, could accomplish tasks even requiring great accuracy. The subjects spontaneously adopted a pattern of moving cautiously, then waiting to see the results of their actions. In experiments with a six degree-of-freedom master-slave manipulator system and time delays of 1.0 to 6 s, Black 2 saw that subjects tried to use the move-and-wait strategy; but there were often difficulties. The subjects seemed to have a problem in holding the master arm stationary while waiting for feedback. Any undesired drifting of the master arm introduced a discrepancy between the positions of the master and slave. This discrepancy was not perceived because of the time delay. The subject would then begin his next move with an inherent error. The difficulty of effectively using the move-and-wait strategy with a master-slave manipulator suggested that rate control might be a more effective control mode with time delay.

TIMEDELN: A programme for the detection and parametrization of overlapping resonances using the time-delay method

NASA Astrophysics Data System (ADS)

Little, Duncan A.; Tennyson, Jonathan; Plummer, Martin; Noble, Clifford J.; Sunderland, Andrew G.

2017-06-01

TIMEDELN implements the time-delay method of determining resonance parameters from the characteristic Lorentzian form displayed by the largest eigenvalues of the time-delay matrix. TIMEDELN constructs the time-delay matrix from input K-matrices and analyses its eigenvalues. This new version implements multi-resonance fitting and may be run serially or as a high performance parallel code with three levels of parallelism. TIMEDELN takes K-matrices from a scattering calculation, either read from a file or calculated on a dynamically adjusted grid, and calculates the time-delay matrix. This is then diagonalized, with the largest eigenvalue representing the longest time-delay experienced by the scattering particle. A resonance shows up as a characteristic Lorentzian form in the time-delay: the programme searches the time-delay eigenvalues for maxima and traces resonances when they pass through different eigenvalues, separating overlapping resonances. It also performs the fitting of the calculated data to the Lorentzian form and outputs resonance positions and widths. Any remaining overlapping resonances can be fitted jointly. The branching ratios of decay into the open channels can also be found. The programme may be run serially or in parallel with three levels of parallelism. The parallel code modules are abstracted from the main physics code and can be used independently.

14 CFR 417.221 - Time delay analysis.

Code of Federal Regulations, 2010 CFR

2010-01-01

... OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.221 Time delay analysis. (a) General. A flight safety analysis must include a time delay analysis that establishes the mean elapsed time between the violation of a flight termination rule and the time when the flight safety system is...

14 CFR 417.221 - Time delay analysis.

Code of Federal Regulations, 2011 CFR

2011-01-01

... OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.221 Time delay analysis. (a) General. A flight safety analysis must include a time delay analysis that establishes the mean elapsed time between the violation of a flight termination rule and the time when the flight safety system is...

49 CFR 236.831 - Time, delay.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Time, delay. 236.831 Section 236.831 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Time, delay. As applied to an automatic train stop or train control system, the time which elapses...

Lesions Responsible for Delayed Oral Transit Time in Post-stroke Dysphagia.

PubMed

Moon, Hyun Im; Yoon, Seo Yeon; Yi, Tae Im; Jeong, Yoon Jeong; Cho, Tae Hwan

2018-06-01

Some stroke patients show oral phase dysphagia, characterized by a markedly prolonged oral transit time that hinders oral feeding. The aim of this study was to clarify the clinical characteristics and lesions responsible for delayed swallowing. We reviewed 90 patients with stroke. The oral processing time plus the postfaucial aggregation time required to swallow semisolid food was assessed. The patients were divided into two groups according to oral transit time, and we analyzed the differences in characteristics such as demographic factors, lesion factors, and cognitive function. Logistic regression analyses were performed to examine the predictors of delayed oral transit time. Lesion location and volume were measured on brain magnetic resonance images. We generated statistic maps of lesions related to delayed oral phase in swallowing using voxel-based lesion symptom mapping (VLSM). The group of patients who showed delayed oral transit time had significantly low cognitive function. Also, in a regression model, delayed oral phase was predicted with low K-MMSE (Korean version of the Mini Mental Status Exam). Using VLSM, we found the lesion location to be associated with delayed oral phase after adjusting for K-MMSE score. Although these results did not reach statistical significance, they showed the lesion pattern with predominant distribution in the left frontal lobe. Delayed oral phase in post-stroke patients was not negligible clinically. Patients' cognitive impairments affect the oral transit time. When adjusting it, we found a trend that the lesion responsible for delayed oral phase was located in the left frontal lobe, though the association did not reach significance. The delay might be related to praxis function.

The effect of visual-motion time-delays on pilot performance in a simulated pursuit tracking task

NASA Technical Reports Server (NTRS)

Miller, G. K., Jr.; Riley, D. R.

1977-01-01

An experimental study was made to determine the effect on pilot performance of time delays in the visual and motion feedback loops of a simulated pursuit tracking task. Three major interrelated factors were identified: task difficulty either in the form of airplane handling qualities or target frequency, the amount and type of motion cues, and time delay itself. In general, the greater the task difficulty, the smaller the time delay that could exist without degrading pilot performance. Conversely, the greater the motion fidelity, the greater the time delay that could be tolerated. The effect of motion was, however, pilot dependent.

Optimal estimation of parameters and states in stochastic time-varying systems with time delay

NASA Astrophysics Data System (ADS)

Torkamani, Shahab; Butcher, Eric A.

2013-08-01

In this study estimation of parameters and states in stochastic linear and nonlinear delay differential systems with time-varying coefficients and constant delay is explored. The approach consists of first employing a continuous time approximation to approximate the stochastic delay differential equation with a set of stochastic ordinary differential equations. Then the problem of parameter estimation in the resulting stochastic differential system is represented as an optimal filtering problem using a state augmentation technique. By adapting the extended Kalman-Bucy filter to the resulting system, the unknown parameters of the time-delayed system are estimated from noise-corrupted, possibly incomplete measurements of the states.

Opto-VLSI-based photonic true-time delay architecture for broadband adaptive nulling in phased array antennas.

PubMed

Juswardy, Budi; Xiao, Feng; Alameh, Kamal

2009-03-16

This paper proposes a novel Opto-VLSI-based tunable true-time delay generation unit for adaptively steering the nulls of microwave phased array antennas. Arbitrary single or multiple true-time delays can simultaneously be synthesized for each antenna element by slicing an RF-modulated broadband optical source and routing specific sliced wavebands through an Opto-VLSI processor to a high-dispersion fiber. Experimental results are presented, which demonstrate the principle of the true-time delay unit through the generation of 5 arbitrary true-time delays of up to 2.5 ns each. (c) 2009 Optical Society of America

Tribological Properties of Surface-Textured and Plasma-Nitrided Pure Titanium Under Oil Lubrication Condition

NASA Astrophysics Data System (ADS)

Zhang, Baosen; Dong, Qiangsheng; Ba, Zhixin; Wang, Zhangzhong; Shi, Hancheng; Xue, Yanting

2018-01-01

Plasma nitriding was conducted as post-treatment for surface texture on pure titanium to obtain a continuous nitriding layer. Supersonic fine particles bombarding (SFPB) was carried out to prepare surface texture. The surface morphologies and chemical composition were analyzed using scanning electron microscope and energy disperse spectroscopy. The microstructures of modified layers were characterized by transmission electron microscope. The tribological properties of surface-textured and duplex-treated pure titanium under oil lubrication condition were systematically investigated in the ball-on-plate reciprocating mode. The effects of applied load and sliding velocity on the tribological behavior were analyzed. The results show that after duplex treatments, the grains size in modified layer becomes slightly larger, and hardness is obviously improved. Wear resistance of duplex-treated pure titanium is significantly improved referenced to untreated and surface-textured pure titanium, which is 3.22 times as much as untreated pure titanium and 2.15 times of that for surface-textured pure titanium, respectively.

Short communication: Jersey × Holstein crossbreds compared with pure Holsteins for body weight, body condition score, fertility, and survival during the first three lactations.

PubMed

Heins, B J; Hansen, L B; Hazel, A R; Seykora, A J; Johnson, D G; Linn, J G

2012-07-01

Crossbred cows (n=80) resulting from the use of Jersey (JE) semen on their pure Holstein (HO) dams were compared with pure HO cows (n=77) for body weight, body condition score, fertility, and survival during their first 3 lactations. Cows were in 2 research herds of the University of Minnesota and calved from September 2003 to June 2008. The JE × HO crossbred cows had significantly less body weight during the first (-56 kg), second (-67 kg), and third (-82 kg) lactations than pure HO cows. However, JE × HO cows had significantly greater body condition score during the first (2.94 vs. 2.84), second (2.97 vs. 2.84), and third (2.99 vs. 2.87) lactations than pure HO cows. For fertility, JE × HO cows had fewer days to first breeding during the first (-10.6d), second (-8.4d), and third (-12.3d) lactations than pure HO cows. Crossbred cows were not significantly different from pure HO cows for number of services during first lactation; however, JE × HO cows had significantly fewer services (2.2) than pure HO cows (2.7) during the second lactation. Also, JE × HO cows had significantly fewer days open than pure HO cows in the first (-24 d), second (-42 d), and third (-42 d) lactations. For survival, JE × HO cows were not significantly different from pure HO cows for percentage of cows calving a second time; however, a tendency existed for a higher percentage of JE × HO cows (63.8%) than pure HO cows (49.4%) to calve a third time, and a higher percentage of JE × HO cows calved a third time within 28, 34, and 40 mo of first calving than pure HO cows. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Solar oscillation time delay measurement assisted celestial navigation method

NASA Astrophysics Data System (ADS)

Ning, Xiaolin; Gui, Mingzhen; Zhang, Jie; Fang, Jiancheng; Liu, Gang

2017-05-01

Solar oscillation, which causes the sunlight intensity and spectrum frequency change, has been studied in great detail, both observationally and theoretically. In this paper, owing to the existence of solar oscillation, the time delay between the sunlight coming from the Sun directly and the sunlight reflected by the other celestial body such as the satellite of planet or asteroid can be obtained with two optical power meters. Because the solar oscillation time delay is determined by the relative positions of the spacecraft, reflective celestial body and the Sun, it can be adopted as the navigation measurement to estimate the spacecraft's position. The navigation accuracy of single solar oscillation time delay navigation system depends on the time delay measurement accuracy, and is influenced by the distance between spacecraft and reflective celestial body. In this paper, we combine it with the star angle measurement and propose a solar oscillation time delay measurement assisted celestial navigation method for deep space exploration. Since the measurement model of time delay is an implicit function, the Implicit Unscented Kalman Filter (IUKF) is applied. Simulations demonstrate the effectiveness and superiority of this method.

System for sensing droplet formation time delay in a flow cytometer

DOEpatents

Van den Engh, Ger; Esposito, Richard J.

1997-01-01

A droplet flow cytometer system which includes a system to optimize the droplet formation time delay based on conditions actually experienced includes an automatic droplet sampler which rapidly moves a plurality of containers stepwise through the droplet stream while simultaneously adjusting the droplet time delay. Through the system sampling of an actual substance to be processed can be used to minimize the effect of the substances variations or the determination of which time delay is optimal. Analysis such as cell counting and the like may be conducted manually or automatically and input to a time delay adjustment which may then act with analysis equipment to revise the time delay estimate actually applied during processing. The automatic sampler can be controlled through a microprocessor and appropriate programming to bracket an initial droplet formation time delay estimate. When maximization counts through volume, weight, or other types of analysis exists in the containers, the increment may then be reduced for a more accurate ultimate setting. This may be accomplished while actually processing the sample without interruption.

Tunable delay time and Hartman effect in graphene magnetic barriers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ban, Yue; Wang, Lin-Jun; Chen, Xi, E-mail: xchen@shu.edu.cn

2015-04-28

Tunable group delay and Hartman effect have been investigated for massless Dirac electrons in graphene magnetic barriers. In the presence of magnetic field, dwell time is found to be equal to net group delay plus the group delay contributing from the lateral shifts. The group delay times are discussed in both cases of normal and oblique incidence, to clarify the nature of Hartman effect. In addition, the group delay in transmission can be modulated from subluminality to superluminality by adjusting the magnetic field, which may also lead to potential applications in graphene-based microelectronics.

Causes of delay in door-to-balloon time in south-east Asian patients undergoing primary percutaneous coronary intervention.

PubMed

Sim, Wen Jun; Ang, An Shing; Tan, Mae Chyi; Xiang, Wen Wei; Foo, David; Loh, Kwok Kong; Jafary, Fahim Haider; Watson, Timothy James; Ong, Paul Jau Lueng; Ho, Hee Hwa

2017-01-01

To evaluate causes and impact of delay in the door-to-balloon (D2B) time for patients undergoing primary percutaneous coronary intervention (PPCI). From January 2009 to December 2012, 1268 patients (86% male, mean age of 58 ± 12 years) presented to our hospital for ST-elevation myocardial infarction (STEMI) and underwent PPCI. They were divided into two groups: Non-delay defined as D2B time ≤ 90 mins and delay group defined as D2B time > 90 mins. Data were collected retrospectively on baseline clinical characteristics, mode of presentation, angiographic findings, therapeutic modality and inhospital outcome. 202 patients had delay in D2B time. There were more female patients in the delay group. They were older and tend to self-present to hospital. They were less likely to be smokers and have a higher prevalence of prior MI. The incidence of posterior MI was higher in the delay group. They also had a higher incidence of triple vessel disease. The 3 most common reasons for D2B delay was delay in the emergency department (39%), atypical clinical presentation (37.6%) and unstable medical condition requiring stabilisation/computed tomographic imaging (26.7%). The inhospital mortality was numerically higher in the delay group (7.4% versus 4.8%, p = 0.12). Delay in D2B occurred in 16% of our patients undergoing PPCI. Several key factors for delay were identified and warrant further intervention.

Delay-correlation landscape reveals characteristic time delays of brain rhythms and heart interactions

PubMed Central

Lin, Aijing; Liu, Kang K. L.; Bartsch, Ronny P.; Ivanov, Plamen Ch.

2016-01-01

Within the framework of ‘Network Physiology’, we ask a fundamental question of how modulations in cardiac dynamics emerge from networked brain–heart interactions. We propose a generalized time-delay approach to identify and quantify dynamical interactions between physiologically relevant brain rhythms and the heart rate. We perform empirical analysis of synchronized continuous EEG and ECG recordings from 34 healthy subjects during night-time sleep. For each pair of brain rhythm and heart interaction, we construct a delay-correlation landscape (DCL) that characterizes how individual brain rhythms are coupled to the heart rate, and how modulations in brain and cardiac dynamics are coordinated in time. We uncover characteristic time delays and an ensemble of specific profiles for the probability distribution of time delays that underly brain–heart interactions. These profiles are consistently observed in all subjects, indicating a universal pattern. Tracking the evolution of DCL across different sleep stages, we find that the ensemble of time-delay profiles changes from one physiologic state to another, indicating a strong association with physiologic state and function. The reported observations provide new insights on neurophysiological regulation of cardiac dynamics, with potential for broad clinical applications. The presented approach allows one to simultaneously capture key elements of dynamic interactions, including characteristic time delays and their time evolution, and can be applied to a range of coupled dynamical systems. PMID:27044991

Delay-correlation landscape reveals characteristic time delays of brain rhythms and heart interactions

NASA Astrophysics Data System (ADS)

Lin, Aijing; Liu, Kang K. L.; Bartsch, Ronny P.; Ivanov, Plamen Ch.

2016-05-01

Within the framework of `Network Physiology', we ask a fundamental question of how modulations in cardiac dynamics emerge from networked brain-heart interactions. We propose a generalized time-delay approach to identify and quantify dynamical interactions between physiologically relevant brain rhythms and the heart rate. We perform empirical analysis of synchronized continuous EEG and ECG recordings from 34 healthy subjects during night-time sleep. For each pair of brain rhythm and heart interaction, we construct a delay-correlation landscape (DCL) that characterizes how individual brain rhythms are coupled to the heart rate, and how modulations in brain and cardiac dynamics are coordinated in time. We uncover characteristic time delays and an ensemble of specific profiles for the probability distribution of time delays that underly brain-heart interactions. These profiles are consistently observed in all subjects, indicating a universal pattern. Tracking the evolution of DCL across different sleep stages, we find that the ensemble of time-delay profiles changes from one physiologic state to another, indicating a strong association with physiologic state and function. The reported observations provide new insights on neurophysiological regulation of cardiac dynamics, with potential for broad clinical applications. The presented approach allows one to simultaneously capture key elements of dynamic interactions, including characteristic time delays and their time evolution, and can be applied to a range of coupled dynamical systems.

Control of amplitude chimeras by time delay in oscillator networks

NASA Astrophysics Data System (ADS)

Gjurchinovski, Aleksandar; Schöll, Eckehard; Zakharova, Anna

2017-04-01

We investigate the influence of time-delayed coupling in a ring network of nonlocally coupled Stuart-Landau oscillators upon chimera states, i.e., space-time patterns with coexisting partially coherent and partially incoherent domains. We focus on amplitude chimeras, which exhibit incoherent behavior with respect to the amplitude rather than the phase and are transient patterns, and we show that their lifetime can be significantly enhanced by coupling delay. To characterize their transition to phase-lag synchronization (coherent traveling waves) and other coherent structures, we generalize the Kuramoto order parameter. Contrasting the results for instantaneous coupling with those for constant coupling delay, for time-varying delay, and for distributed-delay coupling, we demonstrate that the lifetime of amplitude chimera states and related partially incoherent states can be controlled, i.e., deliberately reduced or increased, depending upon the type of coupling delay.

Time domain passivity controller for 4-channel time-delay bilateral teleoperation.

PubMed

Rebelo, Joao; Schiele, Andre

2015-01-01

This paper presents an extension of the time-domain passivity control approach to a four-channel bilateral controller under the effects of time delays. Time-domain passivity control has been used successfully to stabilize teleoperation systems with position-force and position-position controllers; however, the performance with such control architectures is sub-optimal both with and without time delays. This work extends the network representation of the time-domain passivity controller to the four-channel architecture, which provides perfect transparency to the user without time delay. The proposed architecture is based on modelling the controllers as dependent voltage sources and using only series passivity controllers. The obtained results are shown on a one degree-of-freedom setup and illustrate the stabilization behaviour of the proposed controller when time delay is present in the communication channel.

Factors Associated With the Benefits of Concurrent Administration of Intratympanic Steroid Injection With Oral Steroids in Patients With Acute Acoustic Trauma.

PubMed

Chang, Young-Soo; Bang, Kanghyun; Choi, Nayeon; Kim, Jong Sei; Lee, Gang-Gyu

2018-06-01

To analyze the factors associated with the benefits of concurrent administration of intratympanic steroid injection (ITSI) and oral steroids in patients with acute acoustic trauma (AAT) incurred during military training. Retrospective analysis. Nineteen patients eligible under the criteria established concerning treatment for AAT were retrospectively reviewed in this study. ITSI treatments were administered simultaneously alongside oral prednisolone. Patients were categorized into two groups depending on the time elapsed between exposure to the noise and treatment initiation: 1) "Early Treatment initiation," defined as the treatment being initiated between 3 and 7 days; and 2) "Delayed treatment initiation," defined as the treatment being initiated in >7 days. Pure-tone air conduction threshold audiometry, to record the pure-tone average (PTA) at 2, 4, and 8 kHz, was conducted upon each patient's initial visit, and 1 month after starting treatment. The degree of hearing gain (hearing gain [dB] = [initial PTA] - [final PTA]) was calculated and used as the metric for determining the treatment's outcome. The initial PTA and treatment onset were adopted as possible associated factors. The mean ages of each group were 22.00 ± 2.12 years and 22.83 ± 2.64 years, respectively (p = 0.28). The initial PTAs were 46.41 ± 12.73 dB and 47.22 ± 14.74 dB, respectively (p = 1.00).In the multivariable linear regression analysis, the initial PTA and the treatment initiation showed a significant association (R = 0.37). The unstandardized regression coefficient of the initial PTA was 0.37 (p = 0.04). Patients with early treatment initiation showed significant improvement in the degree of hearing gain compared with delayed treatment initiation (unstandardized regression coefficient = 12.63, p = 0.01). We demonstrated the importance of early treatment onset for maximizing the benefits of concurrent administration of ITSI with oral steroids in patients with AAT suffered during military training. Further evaluation is needed to confirm the factors associated with the efficacy of concurrent ITSI with oral steroids.

Typical teleoperator time delay profiles, phase 2. [remotely controlled manipulator arms

NASA Technical Reports Server (NTRS)

Wetherington, R. D.; Walsh, J. R.

1974-01-01

The results of the second phase of a study on time delays in communications systems applicable to the teleoperator program are presented. Estimates of the maximum time delays that will be encountered and presents time delay profiles are given for (1) ground control to teleoperator in low earth orbit, (2) ground control to teleoperator in geosynchronous orbit, and (3) low earth orbit control to teleoperator in low earth orbit.

VARIABLE TIME DELAY MEANS

DOEpatents

Clemensen, R.E.

1959-11-01

An electrically variable time delay line is described which may be readily controlled simuitaneously with variable impedance matching means coupied thereto such that reflections are prevented. Broadly, the delay line includes a signal winding about a magnetic core whose permeability is electrically variable. Inasmuch as the inductance of the line varies directly with the permeability, the time delay and characteristic impedance of the line both vary as the square root of the permeability. Consequently, impedance matching means may be varied similariy and simultaneously w:th the electrically variable permeability to match the line impedance over the entire range of time delay whereby reflections are prevented.

Simulator study of the effect of visual-motion time delays on pilot tracking performance with an audio side task

NASA Technical Reports Server (NTRS)

Riley, D. R.; Miller, G. K., Jr.

1978-01-01

The effect of time delay was determined in the visual and motion cues in a flight simulator on pilot performance in tracking a target aircraft that was oscillating sinusoidally in altitude only. An audio side task was used to assure the subject was fully occupied at all times. The results indicate that, within the test grid employed, about the same acceptable time delay (250 msec) was obtained for a single aircraft (fighter type) by each of two subjects for both fixed-base and motion-base conditions. Acceptable time delay is defined as the largest amount of delay that can be inserted simultaneously into the visual and motion cues before performance degradation occurs. A statistical analysis of the data was made to establish this value of time delay. Audio side task provided quantitative data that documented the subject's work level.

Wigner time delay and spin-orbit activated confinement resonances

NASA Astrophysics Data System (ADS)

Keating, D. A.; Deshmukh, P. C.; Manson, S. T.

2017-09-01

A study of the photoionization of spin-orbit split subshells of high-Z atoms confined in C60 has been performed using the relativistic-random-phase approximation. Specifically, Hg@C60 5p, Rn@C60 6p and Ra@C60 5d were investigated and the near-threshold confinement resonances in the j = l - 1/2 channels were found to engender structures in the j = l + 1/2 cross sections via correlation in the form of interchannel coupling. These structures are termed spin-orbit induced confinement resonances and they are found to profoundly influence the Wigner time delay spectrum resulting in time delays of tens or hundreds of attoseconds along with dramatic swings in time delay over small energy intervals. Pronounced relativistic effects in time delay are also found. These structures, including their manifestation in time delay spectra, are expected to be general phenomena in the photoionization of spin-orbit doublets in confined high-Z atoms.

Synchronization in a chaotic neural network with time delay depending on the spatial distance between neurons

NASA Astrophysics Data System (ADS)

Tang, Guoning; Xu, Kesheng; Jiang, Luoluo

2011-10-01

The synchronization is investigated in a two-dimensional Hindmarsh-Rose neuronal network by introducing a global coupling scheme with time delay, where the length of time delay is proportional to the spatial distance between neurons. We find that the time delay always disturbs synchronization of the neuronal network. When both the coupling strength and length of time delay per unit distance (i.e., enlargement factor) are large enough, the time delay induces the abnormal membrane potential oscillations in neurons. Specifically, the abnormal membrane potential oscillations for the symmetrically placed neurons form an antiphase, so that the large coupling strength and enlargement factor lead to the desynchronization of the neuronal network. The complete and intermittently complete synchronization of the neuronal network are observed for the right choice of parameters. The physical mechanism underlying these phenomena is analyzed.

Dissipativity and stability analysis of fractional-order complex-valued neural networks with time delay.

PubMed

Velmurugan, G; Rakkiyappan, R; Vembarasan, V; Cao, Jinde; Alsaedi, Ahmed

2017-02-01

As we know, the notion of dissipativity is an important dynamical property of neural networks. Thus, the analysis of dissipativity of neural networks with time delay is becoming more and more important in the research field. In this paper, the authors establish a class of fractional-order complex-valued neural networks (FCVNNs) with time delay, and intensively study the problem of dissipativity, as well as global asymptotic stability of the considered FCVNNs with time delay. Based on the fractional Halanay inequality and suitable Lyapunov functions, some new sufficient conditions are obtained that guarantee the dissipativity of FCVNNs with time delay. Moreover, some sufficient conditions are derived in order to ensure the global asymptotic stability of the addressed FCVNNs with time delay. Finally, two numerical simulations are posed to ensure that the attention of our main results are valuable. Copyright © 2016 Elsevier Ltd. All rights reserved.

Determining delayed admission to intensive care unit for mechanically ventilated patients in the emergency department.

PubMed

Hung, Shih-Chiang; Kung, Chia-Te; Hung, Chih-Wei; Liu, Ber-Ming; Liu, Jien-Wei; Chew, Ghee; Chuang, Hung-Yi; Lee, Wen-Huei; Lee, Tzu-Chi

2014-08-23

The adverse effects of delayed admission to the intensive care unit (ICU) have been recognized in previous studies. However, the definitions of delayed admission varies across studies. This study proposed a model to define "delayed admission", and explored the effect of ICU-waiting time on patients' outcome. This retrospective cohort study included non-traumatic adult patients on mechanical ventilation in the emergency department (ED), from July 2009 to June 2010. The primary outcomes measures were 21-ventilator-day mortality and prolonged hospital stays (over 30 days). Models of Cox regression and logistic regression were used for multivariate analysis. The non-delayed ICU-waiting was defined as a period in which the time effect on mortality was not statistically significant in a Cox regression model. To identify a suitable cut-off point between "delayed" and "non-delayed", subsets from the overall data were made based on ICU-waiting time and the hazard ratio of ICU-waiting hour in each subset was iteratively calculated. The cut-off time was then used to evaluate the impact of delayed ICU admission on mortality and prolonged length of hospital stay. The final analysis included 1,242 patients. The time effect on mortality emerged after 4 hours, thus we deduced ICU-waiting time in ED > 4 hours as delayed. By logistic regression analysis, delayed ICU admission affected the outcomes of 21 ventilator-days mortality and prolonged hospital stay, with odds ratio of 1.41 (95% confidence interval, 1.05 to 1.89) and 1.56 (95% confidence interval, 1.07 to 2.27) respectively. For patients on mechanical ventilation at the ED, delayed ICU admission is associated with higher probability of mortality and additional resource expenditure. A benchmark waiting time of no more than 4 hours for ICU admission is recommended.

Microlensing makes lensed quasar time delays significantly time variable

NASA Astrophysics Data System (ADS)

Tie, S. S.; Kochanek, C. S.

2018-01-01

The time delays of gravitationally lensed quasars are generally believed to be unique numbers whose measurement is limited only by the quality of the light curves and the models for the contaminating contribution of gravitational microlensing to the light curves. This belief is incorrect - gravitational microlensing also produces changes in the actual time delays on the ∼day(s) light-crossing time-scale of the emission region. This is due to a combination of the inclination of the disc relative to the line of sight and the differential magnification of the temperature fluctuations producing the variability. We demonstrate this both mathematically and with direct calculations using microlensing magnification patterns. Measuring these delay fluctuations can provide a physical scale for microlensing observations, removing the need for priors on either the microlens masses or the component velocities. That time delays in lensed quasars are themselves time variable likely explains why repeated delay measurements of individual lensed quasars appear to vary by more than their estimated uncertainties. This effect is also a new important systematic problem for attempts to use time delays in lensed quasars for cosmology or to detect substructures (satellites) in lens galaxies.

Long-time behavior for suspension bridge equations with time delay

NASA Astrophysics Data System (ADS)

Park, Sun-Hye

2018-04-01

In this paper, we consider suspension bridge equations with time delay of the form u_{tt}(x,t) + Δ ^2 u (x,t) + k u^+ (x,t) + a_0 u_t (x,t) + a_1 u_t (x, t- τ ) + f(u(x,t)) = g(x). Many researchers have studied well-posedness, decay rates of energy, and existence of attractors for suspension bridge equations without delay effects. But, as far as we know, there is no work about suspension equations with time delay. In addition, there are not many studies on attractors for other delayed systems. Thus we first provide well-posedness for suspension equations with time delay. And then show the existence of global attractors and the finite dimensionality of the attractors by establishing energy functionals which are related to the norm of the phase space to our problem.

Robust outer synchronization between two nonlinear complex networks with parametric disturbances and mixed time-varying delays

NASA Astrophysics Data System (ADS)

Zhang, Chuan; Wang, Xingyuan; Luo, Chao; Li, Junqiu; Wang, Chunpeng

2018-03-01

In this paper, we focus on the robust outer synchronization problem between two nonlinear complex networks with parametric disturbances and mixed time-varying delays. Firstly, a general complex network model is proposed. Besides the nonlinear couplings, the network model in this paper can possess parametric disturbances, internal time-varying delay, discrete time-varying delay and distributed time-varying delay. Then, according to the robust control strategy, linear matrix inequality and Lyapunov stability theory, several outer synchronization protocols are strictly derived. Simple linear matrix controllers are designed to driver the response network synchronize to the drive network. Additionally, our results can be applied on the complex networks without parametric disturbances. Finally, by utilizing the delayed Lorenz chaotic system as the dynamics of all nodes, simulation examples are given to demonstrate the effectiveness of our theoretical results.

Fixed-base simulator study of the effect of time delays in visual cues on pilot tracking performance

NASA Technical Reports Server (NTRS)

Queijo, M. J.; Riley, D. R.

1975-01-01

Factors were examined which determine the amount of time delay acceptable in the visual feedback loop in flight simulators. Acceptable time delays are defined as delays which significantly affect neither the results nor the manner in which the subject 'flies' the simulator. The subject tracked a target aircraft as it oscillated sinusoidally in a vertical plane only. The pursuing aircraft was permitted five degrees of freedom. Time delays of from 0.047 to 0.297 second were inserted in the visual feedback loop. A side task was employed to maintain the workload constant and to insure that the pilot was fully occupied during the experiment. Tracking results were obtained for 17 aircraft configurations having different longitudinal short-period characteristics. Results show a positive correlation between improved handling qualities and a longer acceptable time delay.

A comprehensive review of prehospital and in-hospital delay times in acute stroke care.

PubMed

Evenson, K R; Foraker, R E; Morris, D L; Rosamond, W D

2009-06-01

The purpose of this study was to systematically review and summarize prehospital and in-hospital stroke evaluation and treatment delay times. We identified 123 unique peer-reviewed studies published from 1981 to 2007 of prehospital and in-hospital delay time for evaluation and treatment of patients with stroke, transient ischemic attack, or stroke-like symptoms. Based on studies of 65 different population groups, the weighted Poisson regression indicated a 6.0% annual decline (P<0.001) in hours/year for prehospital delay, defined from symptom onset to emergency department arrival. For in-hospital delay, the weighted Poisson regression models indicated no meaningful changes in delay time from emergency department arrival to emergency department evaluation (3.1%, P=0.49 based on 12 population groups). There was a 10.2% annual decline in hours/year from emergency department arrival to neurology evaluation or notification (P=0.23 based on 16 population groups) and a 10.7% annual decline in hours/year for delay time from emergency department arrival to initiation of computed tomography (P=0.11 based on 23 population groups). Only one study reported on times from arrival to computed tomography scan interpretation, two studies on arrival to drug administration, and no studies on arrival to transfer to an in-patient setting, precluding generalizations. Prehospital delay continues to contribute the largest proportion of delay time. The next decade provides opportunities to establish more effective community-based interventions worldwide. It will be crucial to have effective stroke surveillance systems in place to better understand and improve both prehospital and in-hospital delays for acute stroke care.

Effects of time delay and pitch control sensitivity in the flared landing

NASA Technical Reports Server (NTRS)

Berthe, C. J.; Chalk, C. R.; Wingarten, N. C.; Grantham, W.

1986-01-01

Between December 1985 and January 1986, a flared landing program was conducted, using the USAF Total In-Flight simulator airplane, to examine time delay effects in a formal manner. Results show that as pitch sensitivity is increased, tolerance to time delay decreases. With the proper selection of pitch sensitivity, Level I performance was maintained with time delays ranging from 150 milliseconds to greater than 300 milliseconds. With higher sensitivity, configurations with Level I performance at 150 milliseconds degraded to level 2 at 200 milliseconds. When metrics of time delay and pitch sensitivity effects are applied to enhance previously developed predictive criteria, the result is an improved prediction technique which accounts for significant closed loop items.

Exact synchronization bound for coupled time-delay systems.

PubMed

Senthilkumar, D V; Pesquera, Luis; Banerjee, Santo; Ortín, Silvia; Kurths, J

2013-04-01

We obtain an exact bound for synchronization in coupled time-delay systems using the generalized Halanay inequality for the general case of time-dependent delay, coupling, and coefficients. Furthermore, we show that the same analysis is applicable to both uni- and bidirectionally coupled time-delay systems with an appropriate evolution equation for their synchronization manifold, which can also be defined for different types of synchronization. The exact synchronization bound assures an exponential stabilization of the synchronization manifold which is crucial for applications. The analytical synchronization bound is independent of the nature of the modulation and can be applied to any time-delay system satisfying a Lipschitz condition. The analytical results are corroborated numerically using the Ikeda system.

Time delay induced different synchronization patterns in repulsively coupled chaotic oscillators

NASA Astrophysics Data System (ADS)

Yao, Chenggui; Yi, Ming; Shuai, Jianwei

2013-09-01

Time delayed coupling plays a crucial role in determining the system's dynamics. We here report that the time delay induces transition from the asynchronous state to the complete synchronization (CS) state in the repulsively coupled chaotic oscillators. In particular, by changing the coupling strength or time delay, various types of synchronous patterns, including CS, antiphase CS, antiphase synchronization (ANS), and phase synchronization, can be generated. In the transition regions between different synchronous patterns, bistable synchronous oscillators can be observed. Furthermore, we show that the time-delay-induced phase flip bifurcation is of key importance for the emergence of CS. All these findings may light on our understanding of neuronal synchronization and information processing in the brain.

Stability analysis of fractional-order Hopfield neural networks with time delays.

PubMed

Wang, Hu; Yu, Yongguang; Wen, Guoguang

2014-07-01

This paper investigates the stability for fractional-order Hopfield neural networks with time delays. Firstly, the fractional-order Hopfield neural networks with hub structure and time delays are studied. Some sufficient conditions for stability of the systems are obtained. Next, two fractional-order Hopfield neural networks with different ring structures and time delays are developed. By studying the developed neural networks, the corresponding sufficient conditions for stability of the systems are also derived. It is shown that the stability conditions are independent of time delays. Finally, numerical simulations are given to illustrate the effectiveness of the theoretical results obtained in this paper. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of coal particles on ignition delay times of methane-air mixture

NASA Astrophysics Data System (ADS)

Fedorov, A. V.; Tropin, D. A.

2018-03-01

The results of numerical investigation of the ignition of a stoichiometric methane-air mixture in the presence of carbon particles with diameters of 20-52 μm in the temperature range 950-1150 K and pressures of 1.5-2.0 MPa are presented. The calculated data of the ignition delay times of coal particles in the coal particles/air mixture and of the ignition delay times of methane and coal particles in the methane/coal particles /air mixture are compared with the experimental ones. A satisfactory agreement of the data on the coal particles ignition delay times and methane ignition delay times in all the mixtures considered is shown.

Stochastic parameter estimation in nonlinear time-delayed vibratory systems with distributed delay

NASA Astrophysics Data System (ADS)

Torkamani, Shahab; Butcher, Eric A.

2013-07-01

The stochastic estimation of parameters and states in linear and nonlinear time-delayed vibratory systems with distributed delay is explored. The approach consists of first employing a continuous time approximation to approximate the delayed integro-differential system with a large set of ordinary differential equations having stochastic excitations. Then the problem of state and parameter estimation in the resulting stochastic ordinary differential system is represented as an optimal filtering problem using a state augmentation technique. By adapting the extended Kalman-Bucy filter to the augmented filtering problem, the unknown parameters of the time-delayed system are estimated from noise-corrupted, possibly incomplete measurements of the states. Similarly, the upper bound of the distributed delay can also be estimated by the proposed technique. As an illustrative example to a practical problem in vibrations, the parameter, delay upper bound, and state estimation from noise-corrupted measurements in a distributed force model widely used for modeling machine tool vibrations in the turning operation is investigated.

Optical resonators for true-time-delay beam steering

NASA Astrophysics Data System (ADS)

Gesell, Leslie H.; Evanko, Stephen M.

1996-06-01

Conventional true time delay beamforming and steering devices rely on switching between various lengths of delay line. Therefore only discrete delays are possible. Proposed is a new photonics concept for true time delay beamforming which provides a finely controlled continuum of delays with switching speeds on the order of 10's of nanoseconds or faster. The architecture uses an array of waveguide cavities with different resonate frequencies to channelize the signal. Each spectral component of the signal is phase shifted by an amount proportional to the frequency of that component and the desired time delay. These phase shifted spectral components are then summed to obtain the delayed signal. This paper provides an overview of the results of a Phase I SBIR contract where this concept has been refined and analyzed. The parameters for an operational system are determined and indication of the feasibility of this approach is given. Among the issues addressed are the requirements of the resonators and the methods necessary to implement fiber optic Bragg gratings as these resonators.

Stability analysis for discrete-time stochastic memristive neural networks with both leakage and probabilistic delays.

PubMed

Liu, Hongjian; Wang, Zidong; Shen, Bo; Huang, Tingwen; Alsaadi, Fuad E

2018-06-01

This paper is concerned with the globally exponential stability problem for a class of discrete-time stochastic memristive neural networks (DSMNNs) with both leakage delays as well as probabilistic time-varying delays. For the probabilistic delays, a sequence of Bernoulli distributed random variables is utilized to determine within which intervals the time-varying delays fall at certain time instant. The sector-bounded activation function is considered in the addressed DSMNN. By taking into account the state-dependent characteristics of the network parameters and choosing an appropriate Lyapunov-Krasovskii functional, some sufficient conditions are established under which the underlying DSMNN is globally exponentially stable in the mean square. The derived conditions are made dependent on both the leakage and the probabilistic delays, and are therefore less conservative than the traditional delay-independent criteria. A simulation example is given to show the effectiveness of the proposed stability criterion. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of sodium borate on the early age hydration of calcium sulfoaluminate cement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Champenois, Jean-Baptiste; Dhoury, Mélanie; Cau Dit Coumes, Céline, E-mail: celine.cau-dit-coumes@cea.fr

Calcium sulfoaluminate (CSA) cements are potential candidates for the conditioning of radioactive wastes with high sodium borate concentrations. This work thus investigates early age hydration of two CSA cements with different gypsum contents (0 to 20%) as a function of the mixing solution composition (borate and NaOH concentrations). Gypsum plays a key role in controlling the reactivity of cement. When the mixing solution is pure water, increasing the gypsum concentration accelerates cement hydration. However, the reverse is observed when the mixing solution contains sodium borate. Until gypsum exhaustion, the pore solution pH remains constant at ~ 10.8, and a poorlymore » crystallized borate compound (ulexite) precipitates. A correlation is established between this transient precipitation and the hydration delay. Decreasing the gypsum content in the binder, or increasing the sodium content in the mixing solution, are two ways of reducing the stability of ulexite, thus decreasing the hydration delay.« less

14 CFR 417.221 - Time delay analysis.

Code of Federal Regulations, 2012 CFR

2012-01-01

... occurs; (2) A flight safety official's decision and reaction time, including variation in human response... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Time delay analysis. 417.221 Section 417... OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.221 Time delay analysis. (a...

14 CFR 417.221 - Time delay analysis.

Code of Federal Regulations, 2014 CFR

2014-01-01

... occurs; (2) A flight safety official's decision and reaction time, including variation in human response... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Time delay analysis. 417.221 Section 417... OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.221 Time delay analysis. (a...

14 CFR 417.221 - Time delay analysis.

Code of Federal Regulations, 2013 CFR

2013-01-01

... occurs; (2) A flight safety official's decision and reaction time, including variation in human response... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Time delay analysis. 417.221 Section 417... OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.221 Time delay analysis. (a...

Symmetry, Hopf bifurcation, and the emergence of cluster solutions in time delayed neural networks.

PubMed

Wang, Zhen; Campbell, Sue Ann

2017-11-01

We consider the networks of N identical oscillators with time delayed, global circulant coupling, modeled by a system of delay differential equations with Z N symmetry. We first study the existence of Hopf bifurcations induced by the coupling time delay and then use symmetric Hopf bifurcation theory to determine how these bifurcations lead to different patterns of symmetric cluster oscillations. We apply our results to a case study: a network of FitzHugh-Nagumo neurons with diffusive coupling. For this model, we derive the asymptotic stability, global asymptotic stability, absolute instability, and stability switches of the equilibrium point in the plane of coupling time delay (τ) and excitability parameter (a). We investigate the patterns of cluster oscillations induced by the time delay and determine the direction and stability of the bifurcating periodic orbits by employing the multiple timescales method and normal form theory. We find that in the region where stability switching occurs, the dynamics of the system can be switched from the equilibrium point to any symmetric cluster oscillation, and back to equilibrium point as the time delay is increased.

Binaural sensitivity changes between cortical on and off responses

PubMed Central

Dahmen, Johannes C.; King, Andrew J.; Schnupp, Jan W. H.

2011-01-01

Neurons exhibiting on and off responses with different frequency tuning have previously been described in the primary auditory cortex (A1) of anesthetized and awake animals, but it is unknown whether other tuning properties, including sensitivity to binaural localization cues, also differ between on and off responses. We measured the sensitivity of A1 neurons in anesthetized ferrets to 1) interaural level differences (ILDs), using unmodulated broadband noise with varying ILDs and average binaural levels, and 2) interaural time delays (ITDs), using sinusoidally amplitude-modulated broadband noise with varying envelope ITDs. We also assessed fine-structure ITD sensitivity and frequency tuning, using pure-tone stimuli. Neurons most commonly responded to stimulus onset only, but purely off responses and on-off responses were also recorded. Of the units exhibiting significant binaural sensitivity nearly one-quarter showed binaural sensitivity in both on and off responses, but in almost all (∼97%) of these units the binaural tuning of the on responses differed significantly from that seen in the off responses. Moreover, averaged, normalized ILD and ITD tuning curves calculated from all units showing significant sensitivity to binaural cues indicated that on and off responses displayed different sensitivity patterns across the population. A principal component analysis of ITD response functions suggested a continuous cortical distribution of binaural sensitivity, rather than discrete response classes. Rather than reflecting a release from inhibition without any functional significance, we propose that binaural off responses may be important to cortical encoding of sound-source location. PMID:21562191

75 FR 41920 - Agency Information Collection; Activity Under OMB Review; Airline Service Quality Performance...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-19

... and analyze air traffic delays. Wheels-up and wheels-down times are used in conjunction with departure and arrival times to show the extent of ground delays. Actual elapsed flight time, wheels-down minus wheels- up time, is compared to scheduled elapsed flight time to identify airborne delays. The reporting...

High resolution digital delay timer

DOEpatents

Martin, Albert D.

1988-01-01

Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay (20) provides a first output signal (24) at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits (26, 28) latch the high resolution data (24) to form a first synchronizing data set (60). A selected time interval has been preset to internal counters (142, 146, 154) and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses (32, 34) count down the counters to generate an internal pulse delayed by an interval which is functionally related to the preset time interval. A second LCD (184) corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD (74) to generate a second set of synchronizing data (76) which is complementary with the first set of synchronizing data (60) for presentation to logic circuits (64). The logic circuits (64) further delay the internal output signal (72) to obtain a proper phase relationship of an output signal (80) with the internal pulses (32, 34). The final delayed output signal (80) thereafter enables the output pulse generator (82) to produce the desired output pulse (84) at the preset time delay interval following input of the trigger pulse (10, 12).

Analyzing Double Delays at Newark Liberty International Airport

NASA Technical Reports Server (NTRS)

Evans, Antony D.; Lee, Paul

2016-01-01

When weather or congestion impacts the National Airspace System, multiple different Traffic Management Initiatives can be implemented, sometimes with unintended consequences. One particular inefficiency that is commonly identified is in the interaction between Ground Delay Programs (GDPs) and time based metering of internal departures, or TMA scheduling. Internal departures under TMA scheduling can take large GDP delays, followed by large TMA scheduling delays, because they cannot be easily fitted into the overhead stream. In this paper we examine the causes of these double delays through an analysis of arrival operations at Newark Liberty International Airport (EWR) from June to August 2010. Depending on how the double delay is defined between 0.3 percent and 0.8 percent of arrivals at EWR experienced double delays in this period. However, this represents between 21 percent and 62 percent of all internal departures in GDP and TMA scheduling. A deep dive into the data reveals that two causes of high internal departure scheduling delays are upstream flights making up time between their estimated departure clearance times (EDCTs) and entry into time based metering, which undermines the sequencing and spacing underlying the flight EDCTs, and high demand on TMA, when TMA airborne metering delays are high. Data mining methods (currently) including logistic regression, support vector machines and K-nearest neighbors are used to predict the occurrence of double delays and high internal departure scheduling delays with accuracies up to 0.68. So far, key indicators of double delay and high internal departure scheduling delay are TMA virtual runway queue size, and the degree to which estimated runway demand based on TMA estimated times of arrival has changed relative to the estimated runway demand based on EDCTs. However, more analysis is needed to confirm this.

Determination of Relevant Neuron–Neuron Connections for Neural Prosthetics Using Time-Delayed Mutual Information: Tutorial and Preliminary Results

PubMed Central

Taghva, Alexander; Song, Dong; Hampson, Robert E.; Deadwyler, Sam A.; Berger, Theodore W.

2013-01-01

BACKGROUND Identification of functional dependence among neurons is a necessary component in both the rational design of neural prostheses as well as in the characterization of network physiology. The objective of this article is to provide a tutorial for neurosurgeons regarding information theory, specifically time-delayed mutual information, and to compare time-delayed mutual information, an information theoretic quantity based on statistical dependence, with cross-correlation, a commonly used metric for this task in a preliminary analysis of rat hippocampal neurons. METHODS Spike trains were recorded from rats performing delayed nonmatch-to-sample task using an array of electrodes surgically implanted into the hippocampus of each hemisphere of the brain. In addition, spike train simulations of positively correlated neurons, negatively correlated neurons, and neurons correlated by nonlinear functions were generated. These were evaluated by time-delayed mutual information (MI) and cross-correlation. RESULTS Application of time-delayed MI to experimental data indicated the optimal bin size for information capture in the CA3-CA1 system was 40 ms, which may provide some insight into the spatiotemporal nature of encoding in the rat hippocampus. On simulated data, time-delayed MI showed peak values at appropriate time lags in positively correlated, negatively correlated, and complexly correlated data. Cross-correlation showed peak and troughs with positively correlated and negatively correlated data, but failed to capture some higher order correlations. CONCLUSIONS Comparison of time-delayed MI to cross-correlation in identification of functionally dependent neurons indicates that the methods are not equivalent. Time-delayed MI appeared to capture some interactions between CA3-CA1 neurons at physiologically plausible time delays missed by cross-correlation. It should be considered as a method for identification of functional dependence between neurons and may be useful in the development of neural prosthetics. PMID:22120279

Determination of relevant neuron-neuron connections for neural prosthetics using time-delayed mutual information: tutorial and preliminary results.

PubMed

Taghva, Alexander; Song, Dong; Hampson, Robert E; Deadwyler, Sam A; Berger, Theodore W

2012-12-01

Identification of functional dependence among neurons is a necessary component in both the rational design of neural prostheses as well as in the characterization of network physiology. The objective of this article is to provide a tutorial for neurosurgeons regarding information theory, specifically time-delayed mutual information, and to compare time-delayed mutual information, an information theoretic quantity based on statistical dependence, with cross-correlation, a commonly used metric for this task in a preliminary analysis of rat hippocampal neurons. Spike trains were recorded from rats performing delayed nonmatch-to-sample task using an array of electrodes surgically implanted into the hippocampus of each hemisphere of the brain. In addition, spike train simulations of positively correlated neurons, negatively correlated neurons, and neurons correlated by nonlinear functions were generated. These were evaluated by time-delayed mutual information (MI) and cross-correlation. Application of time-delayed MI to experimental data indicated the optimal bin size for information capture in the CA3-CA1 system was 40 ms, which may provide some insight into the spatiotemporal nature of encoding in the rat hippocampus. On simulated data, time-delayed MI showed peak values at appropriate time lags in positively correlated, negatively correlated, and complexly correlated data. Cross-correlation showed peak and troughs with positively correlated and negatively correlated data, but failed to capture some higher order correlations. Comparison of time-delayed MI to cross-correlation in identification of functionally dependent neurons indicates that the methods are not equivalent. Time-delayed MI appeared to capture some interactions between CA3-CA1 neurons at physiologically plausible time delays missed by cross-correlation. It should be considered as a method for identification of functional dependence between neurons and may be useful in the development of neural prosthetics. Copyright © 2012 Elsevier Inc. All rights reserved.

Reduced order modelling in searches for continuous gravitational waves - I. Barycentring time delays

NASA Astrophysics Data System (ADS)

Pitkin, M.; Doolan, S.; McMenamin, L.; Wette, K.

2018-06-01

The frequencies and phases of emission from extra-solar sources measured by Earth-bound observers are modulated by the motions of the observer with respect to the source, and through relativistic effects. These modulations depend critically on the source's sky-location. Precise knowledge of the modulations are required to coherently track the source's phase over long observations, for example, in pulsar timing, or searches for continuous gravitational waves. The modulations can be modelled as sky-location and time-dependent time delays that convert arrival times at the observer to the inertial frame of the source, which can often be the Solar system barycentre. We study the use of reduced order modelling for speeding up the calculation of this time delay for any sky-location. We find that the time delay model can be decomposed into just four basis vectors, and with these the delay for any sky-location can be reconstructed to sub-nanosecond accuracy. When compared to standard routines for time delay calculation in gravitational wave searches, using the reduced basis can lead to speed-ups of 30 times. We have also studied components of time delays for sources in binary systems. Assuming eccentricities <0.25, we can reconstruct the delays to within 100 s of nanoseconds, with best case speed-ups of a factor of 10, or factors of two when interpolating the basis for different orbital periods or time stamps. In long-duration phase-coherent searches for sources with sky-position uncertainties, or binary parameter uncertainties, these speed-ups could allow enhancements in their scopes without large additional computational burdens.

Longitudinal Outcomes of Start Time Delay on Sleep, Behavior, and Achievement in High School

PubMed Central

Thacher, Pamela V.; Onyper, Serge V.

2016-01-01

Study Objectives: To establish whether sleep, health, mood, behavior, and academics improved after a 45-minute delay in high school start time, and whether changes persisted longitudinally. Methods: We collected data from school records and student self-report across a number of domains at baseline (May 2012) and at two follow-up time points (November 2012 and May 2013), at a public high school in upstate New York. Students enrolled during academic years (AY) 2011–2012 and 2012–2013 completed the Pittsburgh Sleep Quality Index; the DASS-21; the “Owl-Lark” Scale; the Daytime Sleepiness Index; and a brief self-report of health. Reports from school records regarding attendance, tardiness, disciplinary violations, and academic performance were collected for AY 2010–2011 through 2013–2014. Results: Students delayed but did not extend their sleep period; we found lasting improvements in tardiness and disciplinary violations after the start-time delay, but no changes to other variables. At the first follow-up, students reported 20 minutes longer sleep, driven by later rise times and stable bed times. At the second follow-up, students maintained later rise times but delayed bedtimes, returning total sleep to baseline levels. A delay in rise time, paralleling the delay in the start time that occurred, resulted in less tardiness and decreased disciplinary incidents, but larger improvements to sleep patterns may be necessary to affect health, attendance, sleepiness, and academic performance. Conclusions: Later start times improved tardiness and disciplinary issues at this school district. A delay in start time may be a necessary but not sufficient means to increase sleep time and may depend on preexisting individual differences. Commentary: A commentary on this article appears in this issue on page 267. Citation: Thacher PV, Onyper SV. Longitudinal outcomes of start time delay on sleep, behavior, and achievement in high school. SLEEP 2016;39(2):271–281. PMID:26446106

Stability and Bifurcation Analysis in a Maglev System with Multiple Delays

NASA Astrophysics Data System (ADS)

Zhang, Lingling; Huang, Jianhua; Huang, Lihong; Zhang, Zhizhou

This paper considers the time-delayed feedback control for Maglev system with two discrete time delays. We determine constraints on the feedback time delays which ensure the stability of the Maglev system. An algorithm is developed for drawing a two-parametric bifurcation diagram with respect to two delays τ1 and τ2. Direction and stability of periodic solutions are also determined using the normal form method and center manifold theory by Hassard. The complex dynamical behavior of the Maglev system near the domain of stability is confirmed by exhaustive numerical simulation.

PRECISION TIME-DELAY CIRCUIT

DOEpatents

Creveling, R.

1959-03-17

A tine-delay circuit which produces a delay time in d. The circuit a capacitor, an te back resistance, connected serially with the anode of the diode going to ground. At the start of the time delay a negative stepfunction is applied to the series circuit and initiates a half-cycle transient oscillatory voltage terminated by a transient oscillatory voltage of substantially higher frequency. The output of the delay circuit is taken at the junction of the inductor and diode where a sudden voltage rise appears after the initiation of the higher frequency transient oscillations.

Academic delay of gratification, self-efficacy, and time management among academically unprepared college students.

PubMed

Bembenutty, Héfer

2009-04-01

This study examined the associations between academic delay of gratification, self-efficacy beliefs, and time management among academically unprepared college students participating in a summer-immersion program. This study also examined whether the relation of self-efficacy with time management is mediated by academic delay of gratification. Analysis indicated that self-efficacy was directly associated with time management, as delay of gratification served to mediate this effect partially. Self-efficacy emerged as the strongest positive predictor of academic achievement.

Time delay in atomic photoionization with circularly polarized light

NASA Astrophysics Data System (ADS)

Ivanov, I. A.; Kheifets, A. S.

2013-03-01

We study time delay in atomic photoionization by circularly polarized light. By considering the Li atom in an excited 2p state, we demonstrate a strong time-delay asymmetry between the photoemission of the target electrons that are co- and counter-rotating with the electromagnetic field in the polarization plane. In addition, we observe the time-delay sensitivity to the polar angle of the photoelectron emission in the polarization plane. This modulation depends on the shape and duration of the electromagnetic pulse.

Generating chaos for discrete time-delayed systems via impulsive control.

PubMed

Guan, Zhi-Hong; Liu, Na

2010-03-01

Generating chaos for a class of discrete time-delayed systems via impulsive control is investigated in this paper. With the augmented matrix method, the time-delay impulsive systems can be transformed into a new class of linear discrete impulsive systems. Based on the largest Lyapunov exponent and the boundedness of the systems, some theoretical results about the chaotification for the discrete impulsive systems with time delay are derived and an example is given to visualize the satisfactory control performance.

QT Adaptation and Intrinsic QT Variability in Congenital Long QT Syndrome.

PubMed

Seethala, Srikanth; Singh, Prabhpreet; Shusterman, Vladimir; Ribe, Margareth; Haugaa, Kristina H; Němec, Jan

2015-12-16

Increased variability of QT interval (QTV) has been linked to arrhythmias in animal experiments and multiple clinical situations. Congenital long QT syndrome (LQTS), a pure repolarization disease, may provide important information on the relationship between delayed repolarization and QTV. Twenty-four-hour Holter monitor tracings from 78 genotyped congenital LQTS patients (52 females; 51 LQT1, 23 LQT2, 2 LQT5, 2 JLN, 27 symptomatic; age, 35.2±12.3 years) were evaluated with computer-assisted annotation of RR and QT intervals. Several models of RR-QT relationship were tested in all patients. A model assuming exponential decrease of past RR interval contributions to QT duration with 60-second time constant provided the best data fit. This model was used to calculate QTc and residual "intrinsic" QTV, which cannot be explained by heart rate change. The intrinsic QTV was higher in patients with long QTc (r=0.68; P<10(-4)), and in LQT2 than in LQT1/5 patients (5.65±1.28 vs 4.46±0.82; P<0.0002). Both QTc and intrinsic QTV were similar in symptomatic and asymptomatic patients (467±52 vs 459±53 ms and 5.10±1.19 vs 4.74±1.09, respectively). In LQTS patients, QT interval adaptation to heart rate changes occurs with time constant ≈60 seconds, similar to results reported in control subjects. Intrinsic QTV correlates with the degree of repolarization delay and might reflect action potential instability observed in animal models of LQTS. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Insensitivity of synchronization to network structure in chaotic pendulum systems with time-delay coupling.

PubMed

Yao, Chenggui; Zhan, Meng; Shuai, Jianwei; Ma, Jun; Kurths, Jürgen

2017-12-01

It has been generally believed that both time delay and network structure could play a crucial role in determining collective dynamical behaviors in complex systems. In this work, we study the influence of coupling strength, time delay, and network topology on synchronization behavior in delay-coupled networks of chaotic pendulums. Interestingly, we find that the threshold value of the coupling strength for complete synchronization in such networks strongly depends on the time delay in the coupling, but appears to be insensitive to the network structure. This lack of sensitivity was numerically tested in several typical regular networks, such as different locally and globally coupled ones as well as in several complex networks, such as small-world and scale-free networks. Furthermore, we find that the emergence of a synchronous periodic state induced by time delay is of key importance for the complete synchronization.

Determining collective barrier operation skew in a parallel computer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faraj, Daniel A.

2015-11-24

Determining collective barrier operation skew in a parallel computer that includes a number of compute nodes organized into an operational group includes: for each of the nodes until each node has been selected as a delayed node: selecting one of the nodes as a delayed node; entering, by each node other than the delayed node, a collective barrier operation; entering, after a delay by the delayed node, the collective barrier operation; receiving an exit signal from a root of the collective barrier operation; and measuring, for the delayed node, a barrier completion time. The barrier operation skew is calculated by:more » identifying, from the compute nodes' barrier completion times, a maximum barrier completion time and a minimum barrier completion time and calculating the barrier operation skew as the difference of the maximum and the minimum barrier completion time.« less

Effects of time delays on stability and Hopf bifurcation in a fractional ring-structured network with arbitrary neurons

NASA Astrophysics Data System (ADS)

Huang, Chengdai; Cao, Jinde; Xiao, Min; Alsaedi, Ahmed; Hayat, Tasawar

2018-04-01

This paper is comprehensively concerned with the dynamics of a class of high-dimension fractional ring-structured neural networks with multiple time delays. Based on the associated characteristic equation, the sum of time delays is regarded as the bifurcation parameter, and some explicit conditions for describing delay-dependent stability and emergence of Hopf bifurcation of such networks are derived. It reveals that the stability and bifurcation heavily relies on the sum of time delays for the proposed networks, and the stability performance of such networks can be markedly improved by selecting carefully the sum of time delays. Moreover, it is further displayed that both the order and the number of neurons can extremely influence the stability and bifurcation of such networks. The obtained criteria enormously generalize and improve the existing work. Finally, numerical examples are presented to verify the efficiency of the theoretical results.

Determining collective barrier operation skew in a parallel computer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faraj, Daniel A.

Determining collective barrier operation skew in a parallel computer that includes a number of compute nodes organized into an operational group includes: for each of the nodes until each node has been selected as a delayed node: selecting one of the nodes as a delayed node; entering, by each node other than the delayed node, a collective barrier operation; entering, after a delay by the delayed node, the collective barrier operation; receiving an exit signal from a root of the collective barrier operation; and measuring, for the delayed node, a barrier completion time. The barrier operation skew is calculated by:more » identifying, from the compute nodes' barrier completion times, a maximum barrier completion time and a minimum barrier completion time and calculating the barrier operation skew as the difference of the maximum and the minimum barrier completion time.« less

Reader Architectures for Wireless Surface Acoustic Wave Sensors.

PubMed

Lurz, Fabian; Ostertag, Thomas; Scheiner, Benedict; Weigel, Robert; Koelpin, Alexander

2018-05-28

Wireless surface acoustic wave (SAW) sensors have some unique features that make them promising for industrial metrology. Their decisive advantage lies in their purely passive operation and the wireless readout capability allowing the installation also at particularly inaccessible locations. Furthermore, they are small, low-cost and rugged components on highly stable substrate materials and thus particularly suited for harsh environments. Nevertheless, a sensor itself does not carry out any measurement but always requires a suitable excitation and interrogation circuit: a reader. A variety of different architectures have been presented and investigated up to now. This review paper gives a comprehensive survey of the present state of reader architectures such as time domain sampling (TDS), frequency domain sampling (FDS) and hybrid concepts for both SAW resonators and reflective SAW delay line sensors. Furthermore, critical performance parameters such as measurement accuracy, dynamic range, update rate, and hardware costs of the state of the art in science and industry are presented, compared and discussed.

A Mathematical Model of Marine Diesel Engine Speed Control System

NASA Astrophysics Data System (ADS)

Sinha, Rajendra Prasad; Balaji, Rajoo

2018-02-01

Diesel engine is inherently an unstable machine and requires a reliable control system to regulate its speed for safe and efficient operation. Also, the diesel engine may operate at fixed or variable speeds depending upon user's needs and accordingly the speed control system should have essential features to fulfil these requirements. This paper proposes a mathematical model of a marine diesel engine speed control system with droop governing function. The mathematical model includes static and dynamic characteristics of the control loop components. Model of static characteristic of the rotating fly weights speed sensing element provides an insight into the speed droop features of the speed controller. Because of big size and large time delay, the turbo charged diesel engine is represented as a first order system or sometimes even simplified to a pure integrator with constant gain which is considered acceptable in control literature. The proposed model is mathematically less complex and quick to use for preliminary analysis of the diesel engine speed controller performance.

Skin temperature reveals the intensity of acute stress

PubMed Central

Herborn, Katherine A.; Graves, James L.; Jerem, Paul; Evans, Neil P.; Nager, Ruedi; McCafferty, Dominic J.; McKeegan, Dorothy E.F.

2015-01-01

Acute stress triggers peripheral vasoconstriction, causing a rapid, short-term drop in skin temperature in homeotherms. We tested, for the first time, whether this response has the potential to quantify stress, by exhibiting proportionality with stressor intensity. We used established behavioural and hormonal markers: activity level and corticosterone level, to validate a mild and more severe form of an acute restraint stressor in hens (Gallus gallus domesticus). We then used infrared thermography (IRT) to non-invasively collect continuous temperature measurements following exposure to these two intensities of acute handling stress. In the comb and wattle, two skin regions with a known thermoregulatory role, stressor intensity predicted the extent of initial skin cooling, and also the occurrence of a more delayed skin warming, providing two opportunities to quantify stress. With the present, cost-effective availability of IRT technology, this non-invasive and continuous method of stress assessment in unrestrained animals has the potential to become common practice in pure and applied research. PMID:26434785

Skin temperature reveals the intensity of acute stress.

PubMed

Herborn, Katherine A; Graves, James L; Jerem, Paul; Evans, Neil P; Nager, Ruedi; McCafferty, Dominic J; McKeegan, Dorothy E F

2015-12-01

Acute stress triggers peripheral vasoconstriction, causing a rapid, short-term drop in skin temperature in homeotherms. We tested, for the first time, whether this response has the potential to quantify stress, by exhibiting proportionality with stressor intensity. We used established behavioural and hormonal markers: activity level and corticosterone level, to validate a mild and more severe form of an acute restraint stressor in hens (Gallus gallus domesticus). We then used infrared thermography (IRT) to non-invasively collect continuous temperature measurements following exposure to these two intensities of acute handling stress. In the comb and wattle, two skin regions with a known thermoregulatory role, stressor intensity predicted the extent of initial skin cooling, and also the occurrence of a more delayed skin warming, providing two opportunities to quantify stress. With the present, cost-effective availability of IRT technology, this non-invasive and continuous method of stress assessment in unrestrained animals has the potential to become common practice in pure and applied research. Copyright © 2015 Elsevier Inc. All rights reserved.

Single-photon blockade in a hybrid cavity-optomechanical system via third-order nonlinearity

NASA Astrophysics Data System (ADS)

Sarma, Bijita; Sarma, Amarendra K.

2018-04-01

Photon statistics in a weakly driven optomechanical cavity, with Kerr-type nonlinearity, are analyzed both analytically and numerically. The single-photon blockade effect is demonstrated via calculations of the zero-time-delay second-order correlation function g (2)(0). The analytical results obtained by solving the Schrödinger equation are in complete conformity with the results obtained through numerical solution of the quantum master equation. A systematic study on the parameter regime for observing photon blockade in the weak coupling regime is reported. The parameter regime where the photon blockade is not realizable due to the combined effect of nonlinearities owing to the optomechanical coupling and the Kerr-effect is demonstrated. The experimental feasibility with state-of-the-art device parameters is discussed and it is observed that photon blockade could be generated at the telecommunication wavelength. An elaborate analysis of the thermal effects on photon antibunching is presented. The system is found to be robust against pure dephasing-induced decoherences and thermal phonon number fluctuations.

Delay-dependent coupling for a multi-agent LTI consensus system with inter-agent delays

NASA Astrophysics Data System (ADS)

Qiao, Wei; Sipahi, Rifat

2014-01-01

Delay-dependent coupling (DDC) is considered in this paper in a broadly studied linear time-invariant multi-agent consensus system in which agents communicate with each other under homogeneous delays, while attempting to reach consensus. The coupling among the agents is designed here as an explicit parameter of this delay, allowing couplings to autonomously adapt based on the delay value, and in order to guarantee stability and a certain degree of robustness in the network despite the destabilizing effect of delay. Design procedures, analysis of convergence speed of consensus, comprehensive numerical studies for the case of time-varying delay, and limitations are presented.

Delay correlation analysis and representation for vital complaint VHDL models

DOEpatents

Rich, Marvin J.; Misra, Ashutosh

2004-11-09

A method and system unbind a rise/fall tuple of a VHDL generic variable and create rise time and fall time generics of each generic variable that are independent of each other. Then, according to a predetermined correlation policy, the method and system collect delay values in a VHDL standard delay file, sort the delay values, remove duplicate delay values, group the delay values into correlation sets, and output an analysis file. The correlation policy may include collecting all generic variables in a VHDL standard delay file, selecting each generic variable, and performing reductions on the set of delay values associated with each selected generic variable.

Pneumatic shutoff and time-delay valve operates at controlled rate

NASA Technical Reports Server (NTRS)

Horning, J. L.; Tomlinson, L. E.

1966-01-01

Shutoff and time delay valve, which incorporates a metering spool that moves at constant velocity under pneumatic pressure and spring compression, increases fluid-flow area at a uniform rate. Diaphragm areas, control cavity volume, and bleed-orifice size may be varied to give any desired combination of time delay and spool travel time.

The phantom robot - Predictive displays for teleoperation with time delay

NASA Technical Reports Server (NTRS)

Bejczy, Antal K.; Kim, Won S.; Venema, Steven C.

1990-01-01

An enhanced teleoperation technique for time-delayed bilateral teleoperator control is discussed. The control technique selected for time delay is based on the use of a high-fidelity graphics phantom robot that is being controlled in real time (without time delay) against the static task image. Thus, the motion of the phantom robot image on the monitor predicts the motion of the real robot. The real robot's motion will follow the phantom robot's motion on the monitor with the communication time delay implied in the task. Real-time high-fidelity graphics simulation of a PUMA arm is generated and overlaid on the actual camera view of the arm. A simple camera calibration technique is used for calibrated graphics overlay. A preliminary experiment is performed with the predictive display by using a very simple tapping task. The results with this simple task indicate that predictive display enhances the human operator's telemanipulation task performance significantly during free motion when there is a long time delay. It appears, however, that either two-view or stereoscopic predictive displays are necessary for general three-dimensional tasks.

Detection and characterization of Budd-Chiari syndrome with inferior vena cava obstruction: Comparison of fixed and flexible delayed scan time of computed tomography venography.

PubMed

Zhou, Peng-Li; Wu, Gang; Han, Xin-Wei; Bi, Yong-Hua; Zhang, Wen-Guang; Wu, Zheng-Yang

2017-06-01

To compare the results of computed tomography venography (CTV) with a fixed and a flexible delayed scan time for Budd-Chiari syndrome (BCS) with inferior vena cava (IVC) obstruction. A total of 209 consecutive BCS patients with IVC obstruction underwent either a CTV with a fixed delayed scan time of 180s (n=87) or a flexible delayed scan time for good image quality according to IVC blood flow in color Doppler ultrasonography (n=122). The IVC blood flow velocity was measured using a color Doppler ultrasound prior to CT scan. Image quality was classified as either good, moderate, or poor. Image quality, surrounding structures and the morphology of the IVC obstruction were compared between the two groups using a χ 2 -test or paired or unpaired t-tests as appropriate. Inter-observer agreement was assessed using Kappa statistics. There was no significant difference in IVC blood flow velocity between the two groups. Overall image quality, surrounding structures and IVC obstruction morphology delineation on the flexible delayed scan time of CTV images were rated better relative to those obtained by fixed delayed scan time of CTV images (p<0.001). Evaluation of CTV data sets was significantly facilitated with flexible delayed scan time of CTV. There were no significant differences in Kappa statistics between Group A and Group B. The flexible delayed scan time of CTV was associated with better detection and more reliable characterization of BCS with IVC obstruction compared to a fixed delayed scan time. Copyright © 2017 Elsevier B.V. All rights reserved.

Impact of geographic distance on appraisal delay for active TB treatment seeking in Uganda: a network analysis of the Kawempe Community Health Cohort Study.

PubMed

Fluegge, Kyle; Malone, LaShaunda L; Nsereko, Mary; Okware, Brenda; Wejse, Christian; Kisingo, Hussein; Mupere, Ezekiel; Boom, W Henry; Stein, Catherine M

2018-06-26

Appraisal delay is the time a patient takes to consider a symptom as not only noticeable, but a sign of illness. The study's objective was to determine the association between appraisal delay in seeking tuberculosis (TB) treatment and geographic distance measured by network travel (driving and pedestrian) time (in minutes) and distance (Euclidean and self-reported) (in kilometers) and to identify other risk factors from selected covariates and how they modify the core association between delay and distance. This was part of a longitudinal cohort study known as the Kawempe Community Health Study based in Kampala, Uganda. The study enrolled households from April 2002 to July 2012. Multivariable interval regression with multiplicative heteroscedasticity was used to assess the impact of time and distance on delay. The delay interval outcome was defined using a comprehensive set of 28 possible self-reported symptoms. The main independent variables were network travel time (in minutes) and Euclidean distance (in kilometers). Other covariates were organized according to the Andersen utilization conceptual framework. A total of 838 patients with both distance and delay data were included in the network analysis. Bivariate analyses did not reveal a significant association of any distance metric with the delay outcome. However, adjusting for patient characteristics and cavitary disease status, the multivariable model indicated that each minute of driving time to the clinic significantly (p = 0.02) and positively predicted 0.25 days' delay. At the median distance value of 47 min, this represented an additional delay of about 12 (95% CI: [3, 21]) days to the mean of 40 days (95% CI: [25, 56]). Increasing Euclidean distance significantly predicted (p = 0.02) reduced variance in the delay outcome, thereby increasing precision of the mean delay estimate. At the median Euclidean distance of 2.8 km, the variance in the delay was reduced by more than 25%. Of the four geographic distance measures, network travel driving time was a better and more robust predictor of mean delay in this setting. Including network travel driving time with other risk factors may be important in identifying populations especially vulnerable to delay.

What you feel is what you see: inverse dynamics estimation underlies the resistive sensation of a delayed cursor.

PubMed

Takamuku, Shinya; Gomi, Hiroaki

2015-07-22

How our central nervous system (CNS) learns and exploits relationships between force and motion is a fundamental issue in computational neuroscience. While several lines of evidence have suggested that the CNS predicts motion states and signals from motor commands for control and perception (forward dynamics), it remains controversial whether it also performs the 'inverse' computation, i.e. the estimation of force from motion (inverse dynamics). Here, we show that the resistive sensation we experience while moving a delayed cursor, perceived purely from the change in visual motion, provides evidence of the inverse computation. To clearly specify the computational process underlying the sensation, we systematically varied the visual feedback and examined its effect on the strength of the sensation. In contrast to the prevailing theory that sensory prediction errors modulate our perception, the sensation did not correlate with errors in cursor motion due to the delay. Instead, it correlated with the amount of exposure to the forward acceleration of the cursor. This indicates that the delayed cursor is interpreted as a mechanical load, and the sensation represents its visually implied reaction force. Namely, the CNS automatically computes inverse dynamics, using visually detected motions, to monitor the dynamic forces involved in our actions. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Operating room efficiency improvement after implementation of a postoperative team assessment.

PubMed

Porta, Christopher R; Foster, Andrew; Causey, Marlin W; Cordier, Patricia; Ozbirn, Roger; Bolt, Stephen; Allison, Dennis; Rush, Robert

2013-03-01

Operating room time is highly resource intensive, and delays can be a source of lost revenue and surgeon frustration. Methods to decrease these delays are important not only for patient care, but to maximize operating room resource utilization. The purpose of this study was to determine the root cause of operating room delays in a standardized manner to help improve overall operating room efficiency. We performed a single-center prospective observational study analyzing operating room utilization and efficiency after implementing an executive-driven standardized postoperative team debriefing system from January 2010 to December 2010. A total of 11,342 procedures were performed over the 1-y study period (elective 86%, urgent 11%, and emergent 3%), with 1.3 million min of operating room time, 865,864 min of surgeon operative time (62.5%), and 162,958 min of anesthesia time (11.8%). Overall, the average operating room delay was 18 min and varied greatly based on the surgical specialty. The longest delays were due to need for radiology (40 min); other significant delays were due to supply issues (22.7 min), surgeon issues (18 min), nursing issues (14 min), and room turnover (14 min). Over the 1-y period, there was a decrease in mean delay duration, averaging a decrease in delay of 0.147 min/mo with an overall 9% decrease in the mean delay times. With regard to overall operating room utilization, there was a 39% decrease in overall un-utilized available OR time that was due to delays, improving efficiency by 2334 min (212 min/mo). During this study interval no sentinel events occurred in the operating room. A standardized postoperative debrief tracking system is highly beneficial in identifying and reducing overall operative delays and improving operating room utilization. Published by Elsevier Inc.

Time-delayed directional beam phased array antenna

DOEpatents

Fund, Douglas Eugene; Cable, John William; Cecil, Tony Myron

2004-10-19

An antenna comprising a phased array of quadrifilar helix or other multifilar antenna elements and a time-delaying feed network adapted to feed the elements. The feed network can employ a plurality of coaxial cables that physically bridge a microstrip feed circuitry to feed power signals to the elements. The cables provide an incremental time delay which is related to their physical lengths, such that replacing cables having a first set of lengths with cables having a second set of lengths functions to change the time delay and shift or steer the antenna's main beam. Alternatively, the coaxial cables may be replaced with a programmable signal processor unit adapted to introduce the time delay using signal processing techniques applied to the power signals.

Methane oxidation behind reflected shock waves: Ignition delay times measured by pressure and flame band emission

NASA Technical Reports Server (NTRS)

Brabbs, T. A.; Robertson, T. F.

1986-01-01

Ignition delay data were recorded for three methane-oxygen-argon mixtures (phi = 0.5, 1.0, 2.0) for the temperature range 1500 to 1920 K. Quiet pressure trances enabled us to obtain delay times for the start of the experimental pressure rise. These times were in good agreement with those obtained from the flame band emission at 3700 A. The data correlated well with the oxygen and methane dependence of Lifshitz, but showed a much stronger temperature dependence (phi = 0.5 delta E = 51.9, phi = 1.0 delta = 58.8, phi = 2.0 delta E = 58.7 Kcal). The effect of probe location on the delay time measurement was studied. It appears that the probe located 83 mm from the reflecting surface measured delay times which may not be related to the initial temperature and pressure. It was estimated that for a probe located 7 mm from the reflecting surface, the measured delay time would be about 10 microseconds too short, and it was suggested that delay times less than 100 microsecond should not be used. The ignition period was defined as the time interval between start of the experimental pressure rise and 50 percent of the ignition pressure. This time interval was measured for three gas mixtures and found to be similar (40 to 60 micro sec) for phi = 1.0 and 0.5 but much longer (100 to 120) microsecond for phi = 2.0. It was suggested that the ignition period would be very useful to the kinetic modeler in judging the agreement between experimental and calculated delay times.

Longitudinal Outcomes of Start Time Delay on Sleep, Behavior, and Achievement in High School.

PubMed

Thacher, Pamela V; Onyper, Serge V

2016-02-01

To establish whether sleep, health, mood, behavior, and academics improved after a 45-minute delay in high school start time, and whether changes persisted longitudinally. We collected data from school records and student self-report across a number of domains at baseline (May 2012) and at two follow-up time points (November 2012 and May 2013), at a public high school in upstate New York. Students enrolled during academic years (AY) 2011-2012 and 2012-2013 completed the Pittsburgh Sleep Quality Index; the DASS-21; the "Owl-Lark" Scale; the Daytime Sleepiness Index; and a brief self-report of health. Reports from school records regarding attendance, tardiness, disciplinary violations, and academic performance were collected for AY 2010-2011 through 2013-2014. Students delayed but did not extend their sleep period; we found lasting improvements in tardiness and disciplinary violations after the start-time delay, but no changes to other variables. At the first follow-up, students reported 20 minutes longer sleep, driven by later rise times and stable bed times. At the second follow-up, students maintained later rise times but delayed bedtimes, returning total sleep to baseline levels. A delay in rise time, paralleling the delay in the start time that occurred, resulted in less tardiness and decreased disciplinary incidents, but larger improvements to sleep patterns may be necessary to affect health, attendance, sleepiness, and academic performance. Later start times improved tardiness and disciplinary issues at this school district. A delay in start time may be a necessary but not sufficient means to increase sleep time and may depend on preexisting individual differences. A commentary on this article appears in this issue on page 267. © 2016 Associated Professional Sleep Societies, LLC.

Design of surface acoustic wave filters for the multiplex transmission system of multilevel inverter circuits

NASA Astrophysics Data System (ADS)

Kubo, Keita; Kanai, Nanae; Kobayashi, Fumiya; Goka, Shigeyoshi; Wada, Keiji; Kakio, Shoji

2017-07-01

We designed surface acoustic wave (SAW) filters for a multiplex transmission system of multilevel inverter circuits, and applied them to a single-phase three-level inverter. To reduce the transmission delay time of the SAW filters, a four-channel SAW filter array was fabricated and its characteristics were measured. The delay time of the SAW filters was <350 ns, and the delay time difference was reduced to ≤184 ns, less than half that previously reported. The SAW filters withstood up to 990 V, which is sufficient for the inverters used in most domestic appliances. A single-phase three-level inverter with the fabricated SAW filters worked with a total delay time shorter than our target delay time of 2.5 µs. The delay time difference of the proposed system was 0.26 µs, which is sufficient for preventing the inverter circuit from short-circuiting. The SAW filters controlled a multilevel inverter system with simple signal wiring and high dielectric withstanding voltages.

Incorporating time-delays in S-System model for reverse engineering genetic networks.

PubMed

Chowdhury, Ahsan Raja; Chetty, Madhu; Vinh, Nguyen Xuan

2013-06-18

In any gene regulatory network (GRN), the complex interactions occurring amongst transcription factors and target genes can be either instantaneous or time-delayed. However, many existing modeling approaches currently applied for inferring GRNs are unable to represent both these interactions simultaneously. As a result, all these approaches cannot detect important interactions of the other type. S-System model, a differential equation based approach which has been increasingly applied for modeling GRNs, also suffers from this limitation. In fact, all S-System based existing modeling approaches have been designed to capture only instantaneous interactions, and are unable to infer time-delayed interactions. In this paper, we propose a novel Time-Delayed S-System (TDSS) model which uses a set of delay differential equations to represent the system dynamics. The ability to incorporate time-delay parameters in the proposed S-System model enables simultaneous modeling of both instantaneous and time-delayed interactions. Furthermore, the delay parameters are not limited to just positive integer values (corresponding to time stamps in the data), but can also take fractional values. Moreover, we also propose a new criterion for model evaluation exploiting the sparse and scale-free nature of GRNs to effectively narrow down the search space, which not only reduces the computation time significantly but also improves model accuracy. The evaluation criterion systematically adapts the max-min in-degrees and also systematically balances the effect of network accuracy and complexity during optimization. The four well-known performance measures applied to the experimental studies on synthetic networks with various time-delayed regulations clearly demonstrate that the proposed method can capture both instantaneous and delayed interactions correctly with high precision. The experiments carried out on two well-known real-life networks, namely IRMA and SOS DNA repair network in Escherichia coli show a significant improvement compared with other state-of-the-art approaches for GRN modeling.

IDENTIFYING ANOMALIES IN GRAVITATIONAL LENS TIME DELAYS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Congdon, Arthur B.; Keeton, Charles R.; Nordgren, C. Erik, E-mail: acongdon@jpl.nasa.go, E-mail: keeton@physics.rutgers.ed, E-mail: nordgren@sas.upenn.ed

2010-02-01

We examine the ability of gravitational lens time delays to reveal complex structure in lens potentials. In a previous paper, we predicted how the time delay between the bright pair of images in a 'fold' lens scales with the image separation, for smooth lens potentials. Here we show that the proportionality constant increases with the quadrupole moment of the lens potential, and depends only weakly on the position of the source along the caustic. We use Monte Carlo simulations to determine the range of time delays that can be produced by realistic smooth lens models consisting of isothermal ellipsoid galaxiesmore » with tidal shear. We can then identify outliers as 'time delay anomalies'. We find evidence for anomalies in close image pairs in the cusp lenses RX J1131 - 1231 and B1422+231. The anomalies in RX J1131 - 1231 provide strong evidence for substructure in the lens potential, while at this point the apparent anomalies in B1422+231 mainly indicate that the time delay measurements need to be improved. We also find evidence for time delay anomalies in larger-separation image pairs in the fold lenses, B1608+656 and WFI 2033 - 4723, and the cusp lens RX J0911+0551. We suggest that these anomalies are caused by some combination of substructure and a complex lens environment. Finally, to assist future monitoring campaigns we use our smooth models with shear to predict the time delays for all known four-image lenses.« less

Identifying Anomalies in Gravitational Lens Time Delays

NASA Astrophysics Data System (ADS)

Congdon, Arthur B.; Keeton, Charles R.; Nordgren, C. Erik

2010-02-01

We examine the ability of gravitational lens time delays to reveal complex structure in lens potentials. In a previous paper, we predicted how the time delay between the bright pair of images in a "fold" lens scales with the image separation, for smooth lens potentials. Here we show that the proportionality constant increases with the quadrupole moment of the lens potential, and depends only weakly on the position of the source along the caustic. We use Monte Carlo simulations to determine the range of time delays that can be produced by realistic smooth lens models consisting of isothermal ellipsoid galaxies with tidal shear. We can then identify outliers as "time delay anomalies." We find evidence for anomalies in close image pairs in the cusp lenses RX J1131 - 1231 and B1422+231. The anomalies in RX J1131 - 1231 provide strong evidence for substructure in the lens potential, while at this point the apparent anomalies in B1422+231 mainly indicate that the time delay measurements need to be improved. We also find evidence for time delay anomalies in larger-separation image pairs in the fold lenses, B1608+656 and WFI 2033 - 4723, and the cusp lens RX J0911+0551. We suggest that these anomalies are caused by some combination of substructure and a complex lens environment. Finally, to assist future monitoring campaigns we use our smooth models with shear to predict the time delays for all known four-image lenses.

COSMOGRAIL XVII: Time Delays for the Quadruply Imaged Quasar PG 1115+080

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonvin, V.; et al.

We present time-delay estimates for the quadruply imaged quasar PG 1115+080. Our resuls are based on almost daily observations for seven months at the ESO MPIA 2.2m telescope at La Silla Observatory, reaching a signal-to-noise ratio of about 1000 per quasar image. In addition, we re-analyse existing light curves from the literature that we complete with an additional three seasons of monitoring with the Mercator telescope at La Palma Observatory. When exploring the possible source of bias we consider the so-called microlensing time delay, a potential source of systematic error so far never directly accounted for in previous time-delay publications.more » In fifteen years of data on PG 1115+080, we find no strong evidence of microlensing time delay. Therefore not accounting for this effect, our time-delay estimates on the individual data sets are in good agreement with each other and with the literature. Combining the data sets, we obtain the most precise time-delay estimates to date on PG 1115+080, with Dt(AB) = 8.3+1.5-1.6 days (18.7% precision), Dt(AC) = 9.9+1.1-1.1 days (11.1%) and Dt(BC) = 18.8+1.6-1.6 days (8.5%). Turning these time delays into cosmological constraints is done in a companion paper that makes use of ground-based Adaptive Optics (AO) with the Keck telescope.« less

Nuclear reactor with internal thimble-type delayed neutron detection system

DOEpatents

Gross, Kenny C.; Poloncsik, John; Lambert, John D. B.

1990-01-01

This invention teaches improved apparatus for the method of detecting a breach in cladded fuel used in a nuclear reactor. The detector apparatus is located in the primary heat exchanger which conveys part of the reactor coolant past at least three separate delayed-neutron detectors mounted in this heat exchanger. The detectors are spaced apart such that the coolant flow time from the core to each detector is different, and these differences are known. The delayed-neutron activity at the detectors is a function of the delay time after the reaction in the fuel until the coolant carrying the delayed-neutron emitter passes the respective detector. This time delay is broken down into separate components including an isotopic holdup time required for the emitter to move through the fuel from the reaction to the coolant at the breach, and two transit times required for the emitter now in the coolant to flow from the breach to the detector loop and then via the loop to the detector. At least two of these time components are determined during calibrated operation of the reactor. Thereafter during normal reactor operation, repeated comparisons are made by the method of regression approximation of the third time component for the best-fit line correlating measured delayed-neutron activity against activity that is approximated according to specific equations. The equations use these time-delay components and known parameter values of the fuel and of the part and emitting daughter isotopes.

Time and decision making: differential contribution of the posterior insular cortex and the striatum during a delay discounting task.

PubMed

Wittmann, Marc; Leland, David S; Paulus, Martin P

2007-06-01

Delay discounting refers to the fact that an immediate reward is valued more than the same reward if it occurs some time in the future. To examine the neural substrates underlying this process, we studied 13 healthy volunteers who repeatedly had to decide between an immediate and parametrically varied delayed hypothetical reward using a delay discounting task during event-related functional magnetic resonance imaging. Subject's preference judgments resulted in different discounting slopes for shorter (<1 year) and for longer (> or =1 year) delays. Neural activation associated with the shorter delays relative to the longer delays was associated with increased activation in the head of the left caudate nucleus and putamen. When individuals selected the delayed relative to the immediate reward, a strong activation was found in bilateral posterior insular cortex. Several brain areas including the left caudate nucleus showed a correlation between the behaviorally determined discounting and brain activation for the contrast of intervals with delays <1 and > or =1 year. These results suggest that (1) the posterior insula, which is a critical component of the decision-making neural network, is involved in delaying gratification and (2) the degree of neural activation in the striatum, which plays a fundamental role in reward prediction and in time estimation, may code for the time delay.

Retrorectal Tumors

PubMed Central

Neale, Jeffrey A.

2011-01-01

Tumors that arise in the retrorectal (presacral) space are uncommon lesions that present with nonspecific signs and symptoms, which lead to difficult diagnoses. For complete evaluation of the lesion, cross-sectional imaging is required to determine the extent of resection and the appropriate surgical approach. Surgical removal leads to favorable outcomes for patients with benign purely cystic retrorectal tumors. Preoperative tissue diagnosis with transperineal and transsacral biopsies of solid or heterogeneous cystic lesions, are essential to determine the necessity of neoadjuvant therapy, which may decrease local recurrence after surgery and avoid an unnecessary delay in systemic therapy. PMID:22942797

Modelling and simulation techniques for membrane biology.

PubMed

Burrage, Kevin; Hancock, John; Leier, André; Nicolau, Dan V

2007-07-01

One of the most important aspects of Computational Cell Biology is the understanding of the complicated dynamical processes that take place on plasma membranes. These processes are often so complicated that purely temporal models cannot always adequately capture the dynamics. On the other hand, spatial models can have large computational overheads. In this article, we review some of these issues with respect to chemistry, membrane microdomains and anomalous diffusion and discuss how to select appropriate modelling and simulation paradigms based on some or all the following aspects: discrete, continuous, stochastic, delayed and complex spatial processes.

Zooming in on children's behavior during delay of gratification: Disentangling impulsigenic and volitional processes underlying self-regulation.

PubMed

Neuenschwander, Regula; Blair, Clancy

2017-02-01

When delaying gratification, both motivational and regulatory processes are likely to be at play; however, the relative contributions of motivational and regulatory influences on delay behavior are unclear. By examining behavioral responses during a delay task, this study sought to examine the motivational (anticipatory behavior) and regulatory mechanisms (executive function and self-control strategies) underlying children's self-regulation. The participants, 65 5- to 9-year-old children (M age =7.19years, SD=0.89), were video-recorded during a delay procedure and later coded for anticipatory behaviors (e.g., gazing intensely at the tablet) and self-control strategies. Children also completed two executive function (EF) tasks. We found that anticipatory behavior was curvilinearly related to delay time. Children showing either very low or very high levels of anticipatory behavior were not able to wait the entire time. Furthermore, our results indicated that anticipatory behavior interacted with EF to predict delay time. Specifically, anticipatory behavior was negatively related to delay time only if EF abilities were low. Finally, self-control strategies also interacted with EF to predict children's ability to delay. Spontaneous engagement in self-control strategies such as fidgeting and engagement in alternative activities were beneficial for children with low EF but were unrelated to delay time for children with high EF. Results indicate the value of examining motivational and regulatory influences on delay behavior. Lapses in self-regulation may be due to the combination of powerful impulsigenic (i.e., anticipatory behavior) and weak volitional processes (i.e., EF, self-control strategies). Copyright © 2016. Published by Elsevier Inc.

Finite-time resilient decentralized control for interconnected impulsive switched systems with neutral delay.

PubMed

Ren, Hangli; Zong, Guangdeng; Hou, Linlin; Yang, Yi

2017-03-01

This paper is concerned with the problem of finite-time control for a class of interconnected impulsive switched systems with neutral delay in which the time-varying delay appears in both the state and the state derivative. The concepts of finite-time boundedness and finite-time stability are respectively extended to interconnected impulsive switched systems with neutral delay for the first time. By applying the average dwell time method, sufficient conditions are first derived to cope with the problem of finite-time boundedness and finite-time stability for interconnected impulsive switched systems with neutral delay. In addition, the purpose of finite-time resilient decentralized control is to construct a resilient decentralized state-feedback controller such that the closed-loop system is finite-time bounded and finite-time stable. All the conditions are formulated in terms of linear matrix inequalities to ensure finite-time boundedness and finite-time stability of the given system. Finally, an example is presented to illustrate the effectiveness of the proposed approach. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Method and apparatus for measuring the intensity and phase of an ultrashort light pulse

DOEpatents

Kane, Daniel J.; Trebino, Rick P.

1998-01-01

The pulse shape I(t) and phase evolution x(t) of ultrashort light pulses are obtained using an instantaneously responding nonlinear optical medium to form a signal pulse. A light pulse, such a laser pulse, is split into a gate pulse and a probe pulse, where the gate pulse is delayed relative to the probe pulse. The gate pulse and the probe pulse are combined within an instantaneously responding optical medium to form a signal pulse functionally related to a temporal slice of the gate pulse corresponding to the time delay of the probe pulse. The signal pulse is then input to a wavelength-selective device to output pulse field information comprising intensity vs. frequency for a first value of the time delay. The time delay is varied over a range of values effective to yield an intensity plot of signal intensity vs. wavelength and delay. In one embodiment, the beams are overlapped at an angle so that a selected range of delay times is within the intersection to produce a simultaneous output over the time delays of interest.

Radar wideband digital beamforming based on time delay and phase compensation

NASA Astrophysics Data System (ADS)

Fu, Wei; Jiang, Defu

2018-07-01

In conventional phased array radars, analogue time delay devices and phase shifters have been used for wideband beamforming. These methods suffer from insertion losses, gain mismatches and delay variations, and they occupy a large chip area. To solve these problems, a compact architecture of digital array antennas based on subarrays was considered. In this study, the receiving beam patterns of wideband linear frequency modulation (LFM) signals were constructed by applying analogue stretch processing via mixing with delayed reference signals at the subarray level. Subsequently, narrowband digital time delaying and phase compensation of the tone signals were implemented with reduced arithmetic complexity. Due to the differences in amplitudes, phases and time delays between channels, severe performance degradation of the beam patterns occurred without corrections. To achieve good beamforming performance, array calibration was performed in each channel to adjust the amplitude, frequency and phase of the tone signal. Using a field-programmable gate array, wideband LFM signals and finite impulse response filters with continuously adjustable time delays were implemented in a polyphase structure. Simulations and experiments verified the feasibility and effectiveness of the proposed digital beamformer.

77 FR 33718 - Taking and Importing Marine Mammals: Taking Marine Mammals Incidental to Navy Training Exercises...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-07

...). Here, the Navy identifies the distance that a marine mammal is likely to travel during the time... typically travel within a given time-delay period (Table 1). Based on acoustic propagation modeling... Speed and Length of Time-Delay Potential Species group Swim speed Time-delay (min) distance traveled (yd...

An active balance board system with real-time control of stiffness and time-delay to assess mechanisms of postural stability.

PubMed

Cruise, Denise R; Chagdes, James R; Liddy, Joshua J; Rietdyk, Shirley; Haddad, Jeffrey M; Zelaznik, Howard N; Raman, Arvind

2017-07-26

Increased time-delay in the neuromuscular system caused by neurological disorders, concussions, or advancing age is an important factor contributing to balance loss (Chagdes et al., 2013, 2016a,b). We present the design and fabrication of an active balance board system that allows for a systematic study of stiffness and time-delay induced instabilities in standing posture. Although current commercial balance boards allow for variable stiffness, they do not allow for manipulation of time-delay. Having two controllable parameters can more accurately determine the cause of balance deficiencies, and allows us to induce instabilities even in healthy populations. An inverted pendulum model of human posture on such an active balance board predicts that reduced board rotational stiffness destabilizes upright posture through board tipping, and limit cycle oscillations about the upright position emerge as feedback time-delay is increased. We validate these two mechanisms of instability on the designed balance board, showing that rotational stiffness and board time-delay induced the predicted postural instabilities in healthy, young adults. Although current commercial balance boards utilize control of rotational stiffness, real-time control of both stiffness and time-delay on an active balance board is a novel and innovative manipulation to reveal balance deficiencies and potentially improve individualized balance training by targeting multiple dimensions contributing to standing balance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Maturation delay for the predators can enhance stable coexistence for a class of prey-predator models.

PubMed

Banerjee, Malay; Takeuchi, Yasuhiro

2017-01-07

Maturation time delay for the predators is introduced in prey-predator models to implicitly model the stage-structure of predators. Most of the prey-predator models with maturation delay are known to exhibit destabilization of coexistence steady-state. Discrete time delay induced destabilization is a common finding, however, this is due to the introduction of time delay with lack of ecological justification. The main objective of the present work is to show the stabilizing role of maturation delay for a class of delayed prey-predator model. To be specific, we consider prey-predator models with strong and weak Allee effects in prey growth and Michaelis-Menten type functional response. We provide ecological justification for the introduction of maturation delay parameter in predator's growth equation. We obtain the conditions for stable and oscillatory coexistence of prey and their specialist predator in case of strong as well as weak Allee effect for non-delayed and delayed models. Apart from the analytical results for the models under consideration, we perform extensive numerical simulations to construct the relevant bifurcation diagrams. Our analytical and supportive numerical findings reveal that delay is not always a destabilizing factor rather the stable coexistence in the presence of time delay depends upon the formulation of the delayed model. The biological implications of the current investigation are provided in the conclusion section. We also explain the validity of obtained results for other types of prey-predator models with a specialist predator. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oscillatory dynamics of an intravenous glucose tolerance test model with delay interval

NASA Astrophysics Data System (ADS)

Shi, Xiangyun; Kuang, Yang; Makroglou, Athena; Mokshagundam, Sriprakash; Li, Jiaxu

2017-11-01

Type 2 diabetes mellitus (T2DM) has become prevalent pandemic disease in view of the modern life style. Both diabetic population and health expenses grow rapidly according to American Diabetes Association. Detecting the potential onset of T2DM is an essential focal point in the research of diabetes mellitus. The intravenous glucose tolerance test (IVGTT) is an effective protocol to determine the insulin sensitivity, glucose effectiveness, and pancreatic β-cell functionality, through the analysis and parameter estimation of a proper differential equation model. Delay differential equations have been used to study the complex physiological phenomena including the glucose and insulin regulations. In this paper, we propose a novel approach to model the time delay in IVGTT modeling. This novel approach uses two parameters to simulate not only both discrete time delay and distributed time delay in the past interval, but also the time delay distributed in a past sub-interval. Normally, larger time delay, either a discrete or a distributed delay, will destabilize the system. However, we find that time delay over a sub-interval might not. We present analytically some basic model properties, which are desirable biologically and mathematically. We show that this relatively simple model provides good fit to fluctuating patient data sets and reveals some intriguing dynamics. Moreover, our numerical simulation results indicate that our model may remove the defect in well known Minimal Model, which often overestimates the glucose effectiveness index.

Modeling of synchronization behavior of bursting neurons at nonlinearly coupled dynamical networks.

PubMed

Çakir, Yüksel

2016-01-01

Synchronization behaviors of bursting neurons coupled through electrical and dynamic chemical synapses are investigated. The Izhikevich model is used with random and small world network of bursting neurons. Various currents which consist of diffusive electrical and time-delayed dynamic chemical synapses are used in the simulations to investigate the influences of synaptic currents and couplings on synchronization behavior of bursting neurons. The effects of parameters, such as time delay, inhibitory synaptic strengths, and decay time on synchronization behavior are investigated. It is observed that in random networks with no delay, bursting synchrony is established with the electrical synapse alone, single spiking synchrony is observed with hybrid coupling. In small world network with no delay, periodic bursting behavior with multiple spikes is observed when only chemical and only electrical synapse exist. Single-spike and multiple-spike bursting are established with hybrid couplings. A decrease in the synchronization measure is observed with zero time delay, as the decay time is increased in random network. For synaptic delays which are above active phase period, synchronization measure increases with an increase in synaptic strength and time delay in small world network. However, in random network, it increases with only an increase in synaptic strength.

[Influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating on pure titanium].

PubMed

Yin, Lu; Yao, Jiang-wu; Xu, De-wen

2010-10-01

The aim of this study was to observed the influence of deposition time on chromatics during nitrogen-doped diamond like carbon coating (N-DLC) on pure titanium by multi impulse are plasma plating machine. Applying multi impulse are plasma plating machine to produce TiN coatings on pure titanium in nitrogen atmosphere, then filming with nitrogen-doped DLC on TiN in methane (10-80 min in every 5 min). The colors of N-DLC were evaluated in the CIE1976 L*a*b* uniform color scale and Mussell notation. The surface morphology of every specimen was analyzed using scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). When changing the time of N-DLC coating deposition, N-DLC surface showed different color. Golden yellow was presented when deposition time was 30 min. SEM showed that crystallization was found in N-DLC coatings, the structure changed from stable to clutter by varying the deposition time. The chromatics of N-DLC coatings on pure titanium could get golden yellow when deposition time was 30 min, then the crystallized structure was stable.

Effects of delayed polymerization time and bracket manipulation on orthodontic resin modified glass ionomer adhesive

NASA Astrophysics Data System (ADS)

Gilbert, Danielle Wiggins

This study examined the effect of varying delayed polymerization times in combination with bracket manipulation on shear bond strength (SBS), degree of conversion (DC), and adhesive remnant index (ARI) score when using a resin modified glass ionomer (RMGI) adhesive. Specimens were divided into three groups of clinically relevant delay times (0.5, 2, and 4-min) to simulate the delay that frequently occurs between bracket placement and manipulation and subsequent light curing. Based on an analysis of variance (alpha=.05), the SBS was not significantly different between the three groups. While one of the goals of this study was to be the first study to quantify DC of RMGI using Raman microspectroscopy, several challenges, including weak peak signal with and without fluorescence, were encountered and as a result, DC could not be determined. A significant difference (p<0.05) in ARI score was detected between the 0.5-min and 4.0-min delay groups with more adhesive remaining on the bracket with increasing delay time. A Spearman correlation between SBS and ARI indicated no positive association between SBS and ARI measures across delay times. The results of this study suggest that clinically relevant delay times of 0.5, 2, and 4-min do not negatively impact the SBS of a RMGI adhesive. However, with increasing delay time, the results suggest that more adhesive might remain on the bracket during debonding. With more adhesive remaining on the bracket, this could be beneficial in that less adhesive needs to be removed from enamel by grinding at the time of bracket removal when orthodontic treatment is completed.

Using a new discretization approach to design a delayed LQG controller

NASA Astrophysics Data System (ADS)

Haraguchi, M.; Hu, H. Y.

2008-07-01

In general, discrete-time controls have become more and more preferable in engineering because of their easy implementation and simple computations. However, the available discretization approaches for the systems having time delays increase the system dimensions and have a high computational cost. This paper presents an effective discretization approach for the continuous-time systems with an input delay. The approach enables one to transform the input-delay system into a delay-free system, but retain the system dimensions unchanged in the state transformation. To demonstrate an application of the approach, this paper presents the design of an LQ regulator for continuous-time systems with an input delay and gives a state observer with a Kalman filter for estimating the full-state vector from some measurements of the system as well. The case studies in the paper well support the efficacy and efficiency of the proposed approach applied to the vibration control of a three-story structure model with the actuator delay taken into account.

Pre-school children with and without developmental delay: behaviour problems and parenting stress over time.

PubMed

Baker, B L; McIntyre, L L; Blacher, J; Crnic, K; Edelbrock, C; Low, C

2003-01-01

Children with intellectual disability are at heightened risk for behaviour problems and diagnosed mental disorder. The present authors studied the early manifestation and continuity of problem behaviours in 205 pre-school children with and without developmental delays. Behaviour problems were quite stable over the year from age 36-48 months. Children with developmental delays were rated higher on behaviour problems than their non-delayed peers, and were three times as likely to score in the clinical range. Mothers and fathers showed high agreement in their rating of child problems, especially in the delayed group. Parenting stress was also higher in the delayed group, but was related to the extent of behaviour problems rather than to the child's developmental delay. Over time, a transactional model fit the relationship between parenting stress and behaviour problems: high parenting stress contributed to a worsening in child behaviour problems over time, and high child behaviour problems contributed to a worsening in parenting stress. Findings for mothers and fathers were quite similar.

49 CFR 236.563 - Delay time.

Code of Federal Regulations, 2011 CFR

2011-10-01

... OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Train Stop, Train Control and Cab Signal Systems Rules and Instructions; Locomotives § 236.563 Delay time. Delay time of automatic train stop or train control system shall not exceed 8 seconds and the spacing of signals to meet the...

Relativistic effects in photoionization: Wigner time delay for the noble gases and IIB atoms

NASA Astrophysics Data System (ADS)

Banerjee, Sourav; Deshmukh, Pranawa; Dolmatov, Valeriy; Kheifets, Anatoli; Manson, Steven

2017-04-01

Time delay in atomic photoionization has been observed in several experiments, and various theoretical and experimental approaches are developing rapidly to obtain a better understanding of this phenomena. Theoretical methods that account for many body correlations include the relativistic random phase approximation (RRPA) and its non-relativistic analogue, RPAE. Calculations using RRPA are performed and the impact of relativistic interactions on Wigner time delay are explored via comparison of this result with RPAE results. In addition, results on Wigner time delay for Zn Cd and Hg are presented.

Delay decomposition at a single server queue with constant service time and multiple inputs. [Waiting time on computer network

NASA Technical Reports Server (NTRS)

Ziegler, C.; Schilling, D. L.

1977-01-01

Two networks consisting of single server queues, each with a constant service time, are considered. The external inputs to each network are assumed to follow some general probability distribution. Several interesting equivalencies that exist between the two networks considered are derived. This leads to the introduction of an important concept in delay decomposition. It is shown that the waiting time experienced by a customer can be decomposed into two basic components called self delay and interference delay.

Finite-time robust stabilization of uncertain delayed neural networks with discontinuous activations via delayed feedback control.

PubMed

Wang, Leimin; Shen, Yi; Sheng, Yin

2016-04-01

This paper is concerned with the finite-time robust stabilization of delayed neural networks (DNNs) in the presence of discontinuous activations and parameter uncertainties. By using the nonsmooth analysis and control theory, a delayed controller is designed to realize the finite-time robust stabilization of DNNs with discontinuous activations and parameter uncertainties, and the upper bound of the settling time functional for stabilization is estimated. Finally, two examples are provided to demonstrate the effectiveness of the theoretical results. Copyright © 2016 Elsevier Ltd. All rights reserved.

Flight Departure Delay and Rerouting Under Uncertainty in En Route Convective Weather

NASA Technical Reports Server (NTRS)

Mukherjee, Avijit; Grabbe, Shon; Sridhar, Banavar

2011-01-01

Delays caused by uncertainty in weather forecasts can be reduced by improving traffic flow management decisions. This paper presents a methodology for traffic flow management under uncertainty in convective weather forecasts. An algorithm for assigning departure delays and reroutes to aircraft is presented. Departure delay and route assignment are executed at multiple stages, during which, updated weather forecasts and flight schedules are used. At each stage, weather forecasts up to a certain look-ahead time are treated as deterministic and flight scheduling is done to mitigate the impact of weather on four-dimensional flight trajectories. Uncertainty in weather forecasts during departure scheduling results in tactical airborne holding of flights. The amount of airborne holding depends on the accuracy of forecasts as well as the look-ahead time included in the departure scheduling. The weather forecast look-ahead time is varied systematically within the experiments performed in this paper to analyze its effect on flight delays. Based on the results, longer look-ahead times cause higher departure delays and additional flying time due to reroutes. However, the amount of airborne holding necessary to prevent weather incursions reduces when the forecast look-ahead times are higher. For the chosen day of traffic and weather, setting the look-ahead time to 90 minutes yields the lowest total delay cost.

Passivity of memristive BAM neural networks with leakage and additive time-varying delays

NASA Astrophysics Data System (ADS)

Wang, Weiping; Wang, Meiqi; Luo, Xiong; Li, Lixiang; Zhao, Wenbing; Liu, Linlin; Ping, Yuan

2018-02-01

This paper investigates the passivity of memristive bidirectional associate memory neural networks (MBAMNNs) with leakage and additive time-varying delays. Based on some useful inequalities and appropriate Lyapunov-Krasovskii functionals (LKFs), several delay-dependent conditions for passivity performance are obtained in linear matrix inequalities (LMIs). Moreover, the leakage delays as well as additive delays are considered separately. Finally, numerical simulations are provided to demonstrate the feasibility of the theoretical results.

Time signal distribution in communication networks based on synchronous digital hierarchy

NASA Technical Reports Server (NTRS)

Imaoka, Atsushi; Kihara, Masami

1993-01-01

A new method that uses round-trip paths to accurately measure transmission delay for time synchronization is proposed. The performance of the method in Synchronous Digital Hierarchy networks is discussed. The feature of this method is that it separately measures the initial round trip path delay and the variations in round-trip path delay. The delay generated in SDH equipment is determined by measuring the initial round-trip path delay. In an experiment with actual SDH equipment, the error of initial delay measurement was suppressed to 30ns.

OTDR fiber-optical chemical sensor system for detection and location of hydrocarbon leakage.

PubMed

Buerck, J; Roth, S; Kraemer, K; Mathieu, H

2003-08-15

A distributed sensing system for apolar hydrocarbons is presented which is built from a polymer-clad silica fiber adapted to an optical time domain reflectometer (OTDR) set-up. OTDR measurements allow locating and detecting chemicals by measuring the time delay between short light pulses entering the fiber and discrete changes in the backscatter signals that are caused by local extraction of hydrocarbons into the fiber cladding. The light guiding properties of the fiber are affected by interaction of the extracted chemicals with the evanescent wave light field extending into the fiber cladding. Distributed sensing of pure liquid hydrocarbons (HC) and aqueous HC solutions with a commercially available mini-OTDR adapted to sensing fibers of up to 1km length could be demonstrated. A pulsed laser diode emitting at the 850 nm telecommunication wavelength was applied in the mini-OTDR to locate the HCs by analyzing the step drop (light loss) in the backscatter signal, which is induced by local refractive index (RI) increase in the silicone cladding due to the extracted HC. The prototype instrument can be applied for monitoring hydrocarbon leakage in large technical installations, such as tanks, chemical pipelines or chemical waste disposal containments.

Portable bacterial identification system based on elastic light scatter patterns.

PubMed

Bae, Euiwon; Ying, Dawei; Kramer, Donald; Patsekin, Valery; Rajwa, Bartek; Holdman, Cheryl; Sturgis, Jennifer; Davisson, V Jo; Robinson, J Paul

2012-08-28

Conventional diagnosis and identification of bacteria requires shipment of samples to a laboratory for genetic and biochemical analysis. This process can take days and imposes significant delay to action in situations where timely intervention can save lives and reduce associated costs. To enable faster response to an outbreak, a low-cost, small-footprint, portable microbial-identification instrument using forward scatterometry has been developed. This device, weighing 9 lb and measuring 12 × 6 × 10.5 in., utilizes elastic light scatter (ELS) patterns to accurately capture bacterial colony characteristics and delivers the classification results via wireless access. The overall system consists of two CCD cameras, one rotational and one translational stage, and a 635-nm laser diode. Various software algorithms such as Hough transform, 2-D geometric moments, and the traveling salesman problem (TSP) have been implemented to provide colony count and circularity, centering process, and minimized travel time among colonies. Experiments were conducted with four bacteria genera using pure and mixed plate and as proof of principle a field test was conducted in four different locations where the average classification rate ranged between 95 and 100%.

Effect of Discharge Time on Plasma Electrolytic Borocarbonitriding of Pure Iron

NASA Astrophysics Data System (ADS)

Jin, Xiaoyue; Wu, Jie; Wang, Bin; Yang, Xuan; Chen, Lin; Qu, Yao; Xue, Wenbin

The plasma electrolytic borocarbonitriding (PEB/C/N) process on pure iron was carried out in 25% borax solution with glycerine and carbamide additives under different discharge time at 360V. The morphology and structure of PEB/C/N hardened layers were analyzed by SEM and XRD. The hardness profiles of hardened layers were measured by microhardness test. Corrosion behavior of PEB/C/N layers was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Their wear performance was carried out using a pin-disc friction and wear tester under dry sliding test. The PEB/C/N samples mainly consisted of α-Fe, Fe2B, Fe3C, FeN, FeB, Fe2O3 and Fe4N phases, and the Fe2B phase was the dominant phase in the boride layer. It was found that the thickness of boride layer increased with the discharge time and reached 14μm after 60min treatment. The microhardness of the boride layer was up to 2100HV, which was much higher than that of the bare pure iron (about 150HV). After PEB/C/N treatment, the corrosion resistance of pure iron was slightly improved. The friction coefficient of PEB/C/N treated pure iron decreased to 0.129 from 0.556 of pure iron substrate. The wear rate of the PEB/C/N layer after 60min under dry sliding against ZrO2 ball was only 1/10 of that of the bare pure iron. The PEB/C/N treatment is an effective way to improve the wear behavior of pure iron.

Solar flux forecasting using mutual information with an optimal delay

NASA Technical Reports Server (NTRS)

Ashrafi, S.; Conway, D.; Rokni, M.; Sperling, R.; Roszman, L.; Cooley, J.

1993-01-01

Solar flux F(sub 10.7) directly affects the atmospheric density, thereby changing the lifetime and prediction of satellite orbits. For this reason, accurate forecasting of F(sub 10.7) is crucial for orbit determination of spacecraft. Our attempts to model and forecast F(sub 10.7) uncovered highly entangled dynamics. We concluded that the general lack of predictability in solar activity arises from its nonlinear nature. Nonlinear dynamics allow us to predict F(sub 10.7) more accurately than is possible using stochastic methods for time scales shorter than a characteristic horizon, and with about the same accuracy as using stochastic techniques when the forecasted data exceed this horizon. The forecast horizon is a function of two dynamical invariants: the attractor dimension and the Lyapunov exponent. In recent years, estimation of the attractor dimension reconstructed from a time series has become an important tool in data analysis. In calculating the invariants of the system, the first necessary step is the reconstruction of the attractor for the system from the time-delayed values of the time series. The choice of the time delay is critical for this reconstruction. For an infinite amount of noise-free data, the time delay can, in principle, be chosen almost arbitrarily. However, the quality of the phase portraits produced using the time-delay technique is determined by the value chosen for the delay time. Fraser and Swinney have shown that a good choice for this time delay is the one suggested by Shaw, which uses the first local minimum of the mutual information rather than the autocorrelation function to determine the time delay. This paper presents a refinement of this criterion and applies the refined technique to solar flux data to produce a forecast of the solar activity.

Numerical simulation of flow around the NREL S826 airfoil at moderate Reynolds number using delayed detached Eddy simulation (DDES)

NASA Astrophysics Data System (ADS)

Prytz, Erik R.; Huuse, Øyvind; Müller, Bernhard; Bartl, Jan; Sætran, Lars Roar

2017-07-01

Turbulent flow at Reynolds numbers 5 . 104 to 106 around the NREL S826 airfoil used for wind turbine blades is simulated using delayed detached eddy simulation (DDES). The 3D domain is built as a replica of the low speed wind tunnel at the Norwegian University of Science and Technology (NTNU) with the wind tunnel walls considered as slip walls. The subgrid turbulent kinetic energy is used to model the sub-grid scale in the large eddy simulation (LES) part of DDES. Different Reynoldsaveraged Navier-Stokes (RANS) models are tested in ANSYS Fluent. The realizable k - ∈ model as the RANS model in DDES is found to yield the best agreement of simulated pressure distributions with the experimental data both from NTNU and the Technical University of Denmark (DTU), the latter for a shorter spanwise domain. The present DDES results are in excellent agreement with LES results from DTU. Since DDES requires much fewer cells in the RANS region near the wing surface than LES, DDES is computationally much more efficient than LES. Whereas DDES is able to predict lift and drag in close agreement with experiment up to stall, pure 2D RANS simulations fail near stall. After testing different numerical settings, time step sizes and grids for DDES, a Reynolds number study is conducted. Near stall, separated flow structures, so-called stall cells, are observed in the DDES results.

Economic Costs Avoided by Diagnosing Melanoma Six Months Earlier Justify >100 Benign Biopsies.

PubMed

Aires, Daniel J; Wick, Jo; Shaath, Tarek S; Rajpara, Anand N; Patel, Vikas; Badawi, Ahmed H; Li, Cicy; Fraga, Garth R; Doolittle, Gary; Liu, Deede Y

2016-05-01

New melanoma drugs bring enormous benefits but do so at significant costs. Because melanoma grows deeper and deadlier over time, deeper lesions are costlier due to increased sentinel lymph node biopsy, chemotherapy, and disease-associated income loss. Prior studies have justified pigmented lesion biopsies on a "value per life" basis; by contrast we sought to assess how many biopsies are justified per melanoma found on a purely economic basis. We modeled how melanomas in the United States would behave if diagnosis were delayed by 6 months, eg, not biopsied, only observed until the next surveillance visit. Economic loss from delayed biopsy is the obverse of economic benefit of performing biopsy earlier. Growth rates were based on Liu et al. The results of this study can be applied to all patients presenting to dermatologists with pigmented skin lesions suspicious for melanoma. In-situ melanomas were excluded because no studies to date have modeled growth rates analogous to those for invasive melanoma. We assume conservatively that all melanomas not biopsied initially will be biopsied and treated 6 months later. Major modeled costs are (1) increased sentinel lymph node biopsy, (2) increased chemotherapy for metastatic lesions using increased 5-yr death as metastasis marker, and (3) income loss per melanoma death at $413,370 as previously published. Costs avoided by diagnosing melanoma earlier justify 170 biopsies per melanoma found. Efforts to penalize "unnecessary" biopsies may be economically counterproductive.

J Drugs Dermatol. 2016;15(5):527-532.

Mechanisms of time-based figure-ground segregation.

PubMed

Kandil, Farid I; Fahle, Manfred

2003-11-01

Figure-ground segregation can rely on purely temporal information, that is, on short temporal delays between positional changes of elements in figure and ground (Kandil, F.I. & Fahle, M. (2001) Eur. J. Neurosci., 13, 2004-2008). Here, we investigate the underlying mechanisms by measuring temporal segregation thresholds for various kinds of motion cues. Segregation can rely on monocular first-order motion (based on luminance modulation) and second-order motion cues (contrast modulation) with a high temporal resolution of approximately 20 ms. The mechanism can also use isoluminant motion with a reduced temporal resolution of 60 ms. Figure-ground segregation can be achieved even at presentation frequencies too high for human subjects to inspect successive frames individually. In contrast, when stimuli are presented dichoptically, i.e. separately to both eyes, subjects are unable to perceive any segregation, irrespective of temporal frequency. We propose that segregation in these displays is detected by a mechanism consisting of at least two stages. On the first level, standard motion or flicker detectors signal local positional changes (flips). On the second level, a segregation mechanism combines the local activities of the low-level detectors with high temporal precision. Our findings suggest that the segregation mechanism can rely on monocular detectors but not on binocular mechanisms. Moreover, the results oppose the idea that segregation in these displays is achieved by motion detectors of a higher order (motion-from-motion), but favour mechanisms sensitive to short temporal delays even without activation of higher-order motion detectors.

Probing cochlear tuning and tonotopy in the tiger using otoacoustic emissions.

PubMed

Bergevin, Christopher; Walsh, Edward J; McGee, JoAnn; Shera, Christopher A

2012-08-01

Otoacoustic emissions (sound emitted from the ear) allow cochlear function to be probed noninvasively. The emissions evoked by pure tones, known as stimulus-frequency emissions (SFOAEs), have been shown to provide reliable estimates of peripheral frequency tuning in a variety of mammalian and non-mammalian species. Here, we apply the same methodology to explore peripheral auditory function in the largest member of the cat family, the tiger (Panthera tigris). We measured SFOAEs in 9 unique ears of 5 anesthetized tigers. The tigers, housed at the Henry Doorly Zoo (Omaha, NE), were of both sexes and ranged in age from 3 to 10 years. SFOAE phase-gradient delays are significantly longer in tigers--by approximately a factor of two above 2 kHz and even more at lower frequencies--than in domestic cats (Felis catus), a species commonly used in auditory studies. Based on correlations between tuning and delay established in other species, our results imply that cochlear tuning in the tiger is significantly sharper than in domestic cat and appears comparable to that of humans. Furthermore, the SFOAE data indicate that tigers have a larger tonotopic mapping constant (mm/octave) than domestic cats. A larger mapping constant in tiger is consistent both with auditory brainstem response thresholds (that suggest a lower upper frequency limit of hearing for the tiger than domestic cat) and with measurements of basilar-membrane length (about 1.5 times longer in the tiger than domestic cat).

Design of hybrid optical delay line for automotive radar test system

NASA Astrophysics Data System (ADS)

Son, Byung-Hee; Kim, Kwang-Jin; Li, Ye; Park, Chang-In; Choi, Young-Wan

2015-03-01

In this paper, hybrid optical delay line (HODL) which is demanded on automotive radar test system (RTS) is proposed and demonstrated. HODL is composed with coaxial cable in short delay time (< 32 nsec) and optical fiber in long delay time (>= 32 nsec) which are considering the volume, loss and frequency characteristics. Also, the optical transceiver that has the bandwidth of 1 GHz is designed for frequency modulated continuous wave (FMCW). Experimental results show that the S21 is +/- 0.5 dB in the optical transceiver and +/- 1.7 dB in the whole system at 3.7 GHz ~ 4.7 GHz. The resolution of delay time is 1 ns and the delay flatness is +/- 0.23 ns.

The impact of physicochemical property interactions of iso -octane/ethanol blends on ignition timescales

DOE PAGES

Barraza-Botet, Cesar L.; Luecke, Jon; Zigler, Bradley T.; ...

2018-03-20

This work presents new measurements of liquid fuel ignition delay times of iso-octane and ethanol fuel blends obtained from an ignition quality tester at the National Renewable Energy Laboratory (NREL IQT), which are compared to previous ignition delay data from the University of Michigan rapid compression facility (UM RCF), at the same experimental conditions. Pressure-time histories were used to determine liquid fuel ignition delays at global stoichiometric non-premixed conditions for iso-octane, ethanol and iso-octane/ethanol blends of 25, 50, 75% by volume in mixtures of 10% oxygen diluted in nitrogen. Temperatures ranging from 880 to 970 K were studied at amore » pressure of 10 atm. By comparing total ignition delay times from the NREL IQT with chemical ignition delay times from the UM RCF, the contributions of physical phenomena were quantified as representative time scales for spray injection, breakup and evaporation processes, and for gas-phase turbulent mixing. Regression analyses were developed for ignition time scales as function of blend level and charge temperature. Non-dimensional analyses were also carried out to determine the relative effects of physical time scales with respect to chemical ignition delay times.« less

The impact of physicochemical property interactions of iso -octane/ethanol blends on ignition timescales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barraza-Botet, Cesar L.; Luecke, Jon; Zigler, Bradley T.

This work presents new measurements of liquid fuel ignition delay times of iso-octane and ethanol fuel blends obtained from an ignition quality tester at the National Renewable Energy Laboratory (NREL IQT), which are compared to previous ignition delay data from the University of Michigan rapid compression facility (UM RCF), at the same experimental conditions. Pressure-time histories were used to determine liquid fuel ignition delays at global stoichiometric non-premixed conditions for iso-octane, ethanol and iso-octane/ethanol blends of 25, 50, 75% by volume in mixtures of 10% oxygen diluted in nitrogen. Temperatures ranging from 880 to 970 K were studied at amore » pressure of 10 atm. By comparing total ignition delay times from the NREL IQT with chemical ignition delay times from the UM RCF, the contributions of physical phenomena were quantified as representative time scales for spray injection, breakup and evaporation processes, and for gas-phase turbulent mixing. Regression analyses were developed for ignition time scales as function of blend level and charge temperature. Non-dimensional analyses were also carried out to determine the relative effects of physical time scales with respect to chemical ignition delay times.« less

A New Method to Test the Einstein’s Weak Equivalence Principle

NASA Astrophysics Data System (ADS)

Yu, Hai; Xi, Shao-Qiang; Wang, Fa-Yin

2018-06-01

The Einstein’s weak equivalence principle (WEP) is one of the foundational assumptions of general relativity and some other gravity theories. In the theory of parametrized post-Newtonian (PPN), the difference between the PPN parameters γ of different particles or the same type of particle with different energies, Δγ, represents the violation of WEP. Current constraints on Δγ are derived from the observed time delay between correlated particles of astronomical sources. However, the observed time delay is contaminated by other effects, such as the time delays due to different particle emission times, the potential Lorentz invariance violation, and none-zero photon rest mass. Therefore, current constraints are only upper limits. Here, we propose a new method to test WEP based on the fact that the gravitational time delay is direction-dependent while others are not. This is the first method that can naturally correct other time-delay effects. Using the time-delay measurements of BASTE gamma-ray burst sample and the gravitational potential of local super galaxy cluster Laniakea, we find that the constraint on Δγ of different energy photons can be as low as 10‑14. In the future, if more gravitational wave events and fast radio bursts with much more precise time-delay measurements are observed, this method can give a reliable and tight constraint on WEP.

Non-Gaussian noise-weakened stability in a foraging colony system with time delay

NASA Astrophysics Data System (ADS)

Dong, Xiaohui; Zeng, Chunhua; Yang, Fengzao; Guan, Lin; Xie, Qingshuang; Duan, Weilong

2018-02-01

In this paper, the dynamical properties in a foraging colony system with time delay and non-Gaussian noise were investigated. Using delay Fokker-Planck approach, the stationary probability distribution (SPD), the associated relaxation time (ART) and normalization correlation function (NCF) are obtained, respectively. The results show that: (i) the time delay and non-Gaussian noise can induce transition from a single peak to double peaks in the SPD, i.e., a type of bistability occurring in a foraging colony system where time delay and non-Gaussian noise not only cause transitions between stable states, but also construct the states themselves. Numerical simulations are presented and are in good agreement with the approximate theoretical results; (ii) there exists a maximum in the ART as a function of the noise intensity, this maximum for ART is identified as the characteristic of the non-Gaussian noise-weakened stability of the foraging colonies in the steady state; (iii) the ART as a function of the noise correlation time exhibits a maximum and a minimum, where the minimum for ART is identified as the signature of the non-Gaussian noise-enhanced stability of the foraging colonies; and (iv) the time delay can enhance the stability of the foraging colonies in the steady state, while the departure from Gaussian noise can weaken it, namely, the time delay and departure from Gaussian noise play opposite roles in ART or NCF.

Truncated Linear Statistics Associated with the Eigenvalues of Random Matrices II. Partial Sums over Proper Time Delays for Chaotic Quantum Dots

NASA Astrophysics Data System (ADS)

Grabsch, Aurélien; Majumdar, Satya N.; Texier, Christophe

2017-06-01

Invariant ensembles of random matrices are characterized by the distribution of their eigenvalues \\{λ _1,\\ldots ,λ _N\\}. We study the distribution of truncated linear statistics of the form \\tilde{L}=\\sum _{i=1}^p f(λ _i) with p

Radiation dependence of inverter propagation delay from timing sampler measurements

NASA Technical Reports Server (NTRS)

Buehler, M. G.; Blaes, B. R.; Lin, Y.-S.

1989-01-01

A timing sampler consisting of 14 four-stage inverter-pair chains with different load capacitances was fabricated in 1.6-micron n-well CMOS and irradiated with cobalt-60 at 10 rad(Si)/s. For this CMOS process the measured results indicate that the rising delay increases by about 2.2 ns/Mrad(Si) and the falling delay increase is very small, i.e., less than 300 ps/Mrad(Si). The amount of radiation-induced delay depends on the size of the load capacitance. The maximum value observed for this effect was 5.65 ns/pF-Mrad(Si). Using a sensitivity analysis, the sensitivity of the rising delay to radiation can be explained by a simple timing model and the radiation sensitivity of dc MOSFET parameters. This same approach could not explain the insensitivity of the falling delay to radiation. This may be due to a failure of the timing model and/or trapping effects.

Micromachined silicon acoustic delay line with improved structural stability and acoustic directivity for real-time photoacoustic tomography

NASA Astrophysics Data System (ADS)

Cho, Young; Kumar, Akhil; Xu, Song; Zou, Jun

2017-03-01

Recent studies have shown that micromachined silicon acoustic delay lines can provide a promising solution to achieve real-time photoacoustic tomography without the need for complex transducer arrays and data acquisition electronics. However, as its length increases to provide longer delay time, the delay line becomes more vulnerable to structural instability due to reduced mechanical stiffness. In addition, the small cross-section area of the delay line results in a large acoustic acceptance angle and therefore poor directivity. To address these two issues, this paper reports the design, fabrication, and testing of a new silicon acoustic delay line enhanced with 3D printed polymer micro linker structures. First, mechanical deformation of the silicon acoustic delay line (with and without linker structures) under gravity was simulated by using finite element method. Second, the acoustic crosstalk and acoustic attenuation caused by the polymer micro linker structures were evaluated with both numerical simulation and ultrasound transmission testing. The result shows that the use of the polymer micro linker structures significantly improves the structural stability of the silicon acoustic delay lines without creating additional acoustic attenuation and crosstalk. In addition, a new tapered design for the input terminal of the delay line was also investigate to improve its acoustic directivity by reducing the acoustic acceptance angle. These two improvements are expected to provide an effective solution to eliminate current limitations on the achievable acoustic delay time and out-of-plane imaging resolution of micromachined silicon acoustic delay line arrays.

Observer design for compensation of network-induced delays in integrated communication and control systems

NASA Technical Reports Server (NTRS)

Luck, R.; Ray, A.

1988-01-01

A method for compensating the effects of network-induced delays in integrated communication and control systems (ICCS) is proposed, and a finite-dimensional time-invariant ICCS model is developed. The problem of analyzing systems with time-varying and stochastic delays is circumvented by the application of a deterministic observer. For the case of controller-to-actuator delays, the observed design must rely on an extended model which represents the delays as additional states.

Linear stability and nonlinear analyses of traffic waves for the general nonlinear car-following model with multi-time delays

NASA Astrophysics Data System (ADS)

Sun, Dihua; Chen, Dong; Zhao, Min; Liu, Weining; Zheng, Linjiang

2018-07-01

In this paper, the general nonlinear car-following model with multi-time delays is investigated in order to describe the reactions of vehicle to driving behavior. Platoon stability and string stability criteria are obtained for the general nonlinear car-following model. Burgers equation and Korteweg de Vries (KdV) equation and their solitary wave solutions are derived adopting the reductive perturbation method. We investigate the properties of typical optimal velocity model using both analytic and numerical methods, which estimates the impact of delays about the evolution of traffic congestion. The numerical results show that time delays in sensing relative movement is more sensitive to the stability of traffic flow than time delays in sensing host motion.

Biocatalytic Synthesis of the Rare Sugar Kojibiose: Process Scale-Up and Application Testing.

PubMed

Beerens, Koen; De Winter, Karel; Van de Walle, Davy; Grootaert, Charlotte; Kamiloglu, Senem; Miclotte, Lisa; Van de Wiele, Tom; Van Camp, John; Dewettinck, Koen; Desmet, Tom

2017-07-26

Cost-efficient (bio)chemical production processes are essential to evaluate the commercial and industrial applications of promising carbohydrates and also are essential to ensure economically viable production processes. Here, the synthesis of the naturally occurring disaccharide kojibiose (2-O-α-d-glucopyranosyl-d-glucopyranoside) was evaluated using different Bifidobacterium adolescentis sucrose phosphorylase variants. Variant L341I_Q345S was found to efficiently synthesize kojibiose while remaining fully active after 1 week of incubation at 55 °C. Process optimization allowed kojibiose production at the kilogram scale, and simple but efficient downstream processing, using a yeast treatment and crystallization, resulted in more than 3 kg of highly pure crystalline kojibiose (99.8%). These amounts allowed a deeper characterization of its potential in food applications. It was found to have possible beneficial health effects, including delayed glucose release and potential to trigger SCFA production. Finally, we compared the bulk functionality of highly pure kojibiose to that of sucrose, hereby mapping its potential as a new sweetener in confectionery products.

Steroid androgen 17α-methyltestosterone induces malformations and biochemical alterations in zebrafish embryos.

PubMed

Rivero-Wendt, Carla Letícia Gediel; Oliveira, Rhaul; Monteiro, Marta Sofia; Domingues, Inês; Soares, Amadeu Mortágua Velho Maia; Grisolia, Cesar Koppe

2016-06-01

The synthetic androgen 17α-methyltestosterone is widely used in fish aquaculture for sex reversion of female individuals. Little is known about the amount of MT residues reaching the aquatic environment and further impacts in non-target organisms, including fish early-life stages. Thus, in this work, zebrafish embryos were exposed to two forms of 17α-methyltestosterone: the pure compound (MT) and a formulation commonly used in Brazil (cMT). For MT, a 96h-LC50 of 10.09mg/l was calculated. MT also affected embryo development inducing tail malformations, edemas, abnormal development of the head, and hatching delay. At biochemical level MT inhibited vitellogenin (VTG) and inhibited cholinesterase and lactate dehydrogenase. cMT elicited similar patterns of toxicity as the pure compound (MT). Effects reported in this study suggest a potential environmental risk of MT, especially since the VTG effects occurred at environmental relevant concentrations (0.004mg/l). Copyright © 2016 Elsevier B.V. All rights reserved.

Using Constant Time Delay to Teach Braille Word Recognition

ERIC Educational Resources Information Center

Hooper, Jonathan; Ivy, Sarah; Hatton, Deborah

2014-01-01

Introduction: Constant time delay has been identified as an evidence-based practice to teach print sight words and picture recognition (Browder, Ahlbrim-Delzell, Spooner, Mims, & Baker, 2009). For the study presented here, we tested the effectiveness of constant time delay to teach new braille words. Methods: A single-subject multiple baseline…

Impact of time delays on oscillatory dynamics of interlinked positive and negative feedback loops

NASA Astrophysics Data System (ADS)

Huang, Bo; Tian, Xinyu; Liu, Feng; Wang, Wei

2016-11-01

Interlinking a positive feedback loop (PFL) with a negative feedback loop (NFL) constitutes a typical motif in genetic networks, performing various functions in cell signaling. How time delay in feedback regulation affects the dynamics of such systems still remains unclear. Here, we investigate three systems of interlinked PFL and NFL with time delays: a synthetic genetic oscillator, a three-node circuit, and a simplified single-node model. The stability of steady states and the routes to oscillation in the single-node model are analyzed in detail. The amplitude and period of oscillations vary with a pointwise periodicity over a range of time delay. Larger-amplitude oscillations can be induced when the PFL has an appropriately long delay, in comparison with the PFL with no delay or short delay; this conclusion holds true for all the three systems. We unravel the underlying mechanism for the above effects via analytical derivation under a limiting condition. We also develop a stochastic algorithm for simulating a single reaction with two delays and show that robust oscillations can be maintained by the PFL with a properly long delay in the single-node system. This work presents an effective method for constructing robust large-amplitude oscillators and interprets why similar circuit architectures are engaged in timekeeping systems such as circadian clocks.

Estimates of delays in diagnosis of cervical cancer in Nepal

PubMed Central

2014-01-01

Background Cervical cancer is the leading cause of cancer related deaths among women in Nepal. The long symptom to diagnosis interval means that women have advanced disease at presentation. The aim of this study was to identify, estimate and describe the extent of different delays in diagnosis of cervical cancer in Nepal. Methods A cross-sectional descriptive study was conducted in two tertiary cancer hospitals of Nepal. Face to face interview and medical records review were carried out among 110 cervical cancer patients. Total diagnostic delay was categorized into component delays: patient delay, health care providers delay, referral delay and diagnostic waiting time. Results Total 110 patients recruited in the study represented 40 districts from all three ecological regions of the country. Median total diagnostic delay was 157 days with more than three fourth (77.3%) of the patients having longer total diagnostic delay of >90 days. Out of the total diagnostic delay, median patient delay, median health care provider delay, median referral delay and median diagnostic waiting time were 68.5 days, 40 days, 5 days and 9 days respectively. Majority of the patients had experienced longer delay of each type except referral delay. Fifty seven percent of the patients had experienced longer patient delay of >60 days, 90% had suffered longer health care provider delay of >1 week, 31.8% had longer referral delay of >1 week and 66.2% had waited >1 week at diagnostic center for final diagnosis. Variation in each type of delay was observed among women with different attributes and in context of health care service delivery. Conclusions Longer delays were observed in all the diagnostic pathways except for referral delay and diagnostic waiting time. Among the delays, patient delay is of crucial importance because of its longer span, although health care provider delay is equally important. In the context of limited screening services in Nepal, the efforts should be to reduce the diagnostic delay especially patient and health care provider delay for early detection and reduction of mortality rate of cervical cancer. PMID:24533670

Delay discounting as emotional processing: an electrophysiological study.

PubMed

Blackburn, Marianna; Mason, Liam; Hoeksma, Marco; Zandstra, Elizabeth H; El-Deredy, Wael

2012-01-01

Both theoretical models and functional imaging studies implicate the involvement of emotions within the delay discounting process. However, defining this role has been difficult to establish with neuroimaging techniques given the automaticity of emotional responses. To address this, the current study examined electrophysiological correlates involved in the detection and evaluation of immediate and delayed monetary outcomes. Our results showed that modulation of both early and later ERP components previously associated with affective stimuli processing are sensitive to the signalling of delayed rewards. Together with behavioural reaction times that favoured immediacy, we demonstrated, for the first time, that time delays modify the incentive value of monetary rewards via mechanisms of emotional bias and selective visual attention. Furthermore, our data are consistent with the hypothesis that delayed and thus intangible rewards are perceived less saliently, and rely on emotion as a common currency within decision making. This study provides a new approach to delay discounting and highlights a potential novel route through which delay discounting may be investigated.

Improving Procedure Start Times and Decreasing Delays in Interventional Radiology: A Department's Quality Improvement Initiative.

PubMed

Villarreal, Monica C; Rostad, Bradley S; Wright, Richard; Applegate, Kimberly E

2015-12-01

To identify and reduce reasons for delays in procedure start times, particularly the first cases of the day, within the interventional radiology (IR) divisions of the Department of Radiology using principles of continuous quality improvement. An interdisciplinary team representative of the IR and preprocedure/postprocedure care area (PPCA) health care personnel, managers, and data analysts was formed. A standardized form was used to document both inpatient and outpatient progress through the PPCA and IR workflow in six rooms and to document reasons for delays. Data generated were used to identify key problems areas, implement improvement interventions, and monitor their effects. Project duration was 6 months. The average number of on-time starts for the first case of the day increased from 23% to 56% (P value < .01). The average number of on-time, scheduled outpatients increased from 30% to 45% (P value < .01). Patient wait time to arrive at treatment room once they were ready for their procedure was reduced on average by 10 minutes (P value < .01). Patient care delay duration per 100 patients was reduced from 30.3 to 21.6 hours (29% reduction). Number of patient care delays per 100 patients was reduced from 46.6 to 40.1 (17% reduction). Top reasons for delay included waiting for consent (26% of delays duration) and laboratory tests (12%). Many complex factors contribute to procedure start time delays within an IR practice. A data-driven and patient-centered, interdisciplinary team approach was effective in reducing delays in IR. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

Impact of delay on disease outbreak in a spatial epidemic model

NASA Astrophysics Data System (ADS)

Zhao, Xia-Xia; Wang, Jian-Zhong

2015-04-01

One of the central issues in studying epidemic spreading is the mechanism on disease outbreak. In this paper, we investigate the effects of time delay on disease outbreak in spatial epidemics based on a reaction-diffusion model. By mathematical analysis and numerical simulations, we show that when time delay is more than a critical value, the disease outbreaks. The obtained results show that the time delay is an important factor in the spread of the disease, which may provide new insights on disease control.

Delay decomposition at a single server queue with constant service time and multiple inputs

NASA Technical Reports Server (NTRS)

Ziegler, C.; Schilling, D. L.

1978-01-01

Two network consisting of single server queues, each with a constant service time, are considered. The external inputs to each network are assumed to follow some general probability distribution. Several interesting equivalencies that exist between the two networks considered are derived. This leads to the introduction of an important concept in delay decomposition. It is shown that the waiting time experienced by a customer can be decomposed into two basic components called self-delay and interference delay.

Time-delayed feedback control of coherence resonance chimeras

NASA Astrophysics Data System (ADS)

Zakharova, Anna; Semenova, Nadezhda; Anishchenko, Vadim; Schöll, Eckehard

2017-11-01

Using the model of a FitzHugh-Nagumo system in the excitable regime, we investigate the influence of time-delayed feedback on noise-induced chimera states in a network with nonlocal coupling, i.e., coherence resonance chimeras. It is shown that time-delayed feedback allows for the control of the range of parameter values where these chimera states occur. Moreover, for the feedback delay close to the intrinsic period of the system, we find a novel regime which we call period-two coherence resonance chimera.

Application of Time-Delay Absorber to Suppress Vibration of a Dynamical System to Tuned Excitation.

PubMed

El-Ganaini, W A A; El-Gohary, H A

2014-08-01

In this work, we present a comprehensive investigation of the time delay absorber effects on the control of a dynamical system represented by a cantilever beam subjected to tuned excitation forces. Cantilever beam is one of the most widely used system in too many engineering applications, such as mechanical and civil engineering. The main aim of this work is to control the vibration of the beam at simultaneous internal and combined resonance condition, as it is the worst resonance case. Control is conducted via time delay absorber to suppress chaotic vibrations. Time delays often appear in many control systems in the state, in the control input, or in the measurements. Time delay commonly exists in various engineering, biological, and economical systems because of the finite speed of the information processing. It is a source of performance degradation and instability. Multiple time scale perturbation method is applied to obtain a first order approximation for the nonlinear differential equations describing the system behavior. The different resonance cases are reported and studied numerically. The stability of the steady-state solution at the selected worst resonance case is investigated applying Runge-Kutta fourth order method and frequency response equations via Matlab 7.0 and Maple11. Time delay absorber is effective, but within a specified range of time delay. It is the critical factor in selecting such absorber. Time delay absorber is better than the ordinary one as from the effectiveness point of view. The effects of the different absorber parameters on the system behavior and stability are studied numerically. A comparison with the available published work showed a close agreement with some previously published work.

Precise Time Delays from Strongly Gravitationally Lensed Type Ia Supernovae with Chromatically Microlensed Images

NASA Astrophysics Data System (ADS)

Goldstein, Daniel A.; Nugent, Peter E.; Kasen, Daniel N.; Collett, Thomas E.

2018-03-01

Time delays between the multiple images of strongly gravitationally lensed Type Ia supernovae (glSNe Ia) have the potential to deliver precise cosmological constraints, but the effects of microlensing on time delay extraction have not been studied in detail. Here we quantify the effect of microlensing on the glSN Ia yield of the Large Synoptic Survey Telescope (LSST) and the effect of microlensing on the precision and accuracy of time delays that can be extracted from LSST glSNe Ia. Microlensing has a negligible effect on the LSST glSN Ia yield, but it can be increased by a factor of ∼2 over previous predictions to 930 systems using a novel photometric identification technique based on spectral template fitting. Crucially, the microlensing of glSNe Ia is achromatic until three rest-frame weeks after the explosion, making the early-time color curves microlensing-insensitive time delay indicators. By fitting simulated flux and color observations of microlensed glSNe Ia with their underlying, unlensed spectral templates, we forecast the distribution of absolute time delay error due to microlensing for LSST, which is unbiased at the sub-percent level and peaked at 1% for color curve observations in the achromatic phase, while for light-curve observations it is comparable to state-of-the-art mass modeling uncertainties (4%). About 70% of LSST glSN Ia images should be discovered during the achromatic phase, indicating that microlensing time delay uncertainties can be minimized if prompt multicolor follow-up observations are obtained. Accounting for microlensing, the 1–2 day time delay on the recently discovered glSN Ia iPTF16geu can be measured to 40% precision, limiting its cosmological utility.

Delay differential analysis of time series.

PubMed

Lainscsek, Claudia; Sejnowski, Terrence J

2015-03-01

Nonlinear dynamical system analysis based on embedding theory has been used for modeling and prediction, but it also has applications to signal detection and classification of time series. An embedding creates a multidimensional geometrical object from a single time series. Traditionally either delay or derivative embeddings have been used. The delay embedding is composed of delayed versions of the signal, and the derivative embedding is composed of successive derivatives of the signal. The delay embedding has been extended to nonuniform embeddings to take multiple timescales into account. Both embeddings provide information on the underlying dynamical system without having direct access to all the system variables. Delay differential analysis is based on functional embeddings, a combination of the derivative embedding with nonuniform delay embeddings. Small delay differential equation (DDE) models that best represent relevant dynamic features of time series data are selected from a pool of candidate models for detection or classification. We show that the properties of DDEs support spectral analysis in the time domain where nonlinear correlation functions are used to detect frequencies, frequency and phase couplings, and bispectra. These can be efficiently computed with short time windows and are robust to noise. For frequency analysis, this framework is a multivariate extension of discrete Fourier transform (DFT), and for higher-order spectra, it is a linear and multivariate alternative to multidimensional fast Fourier transform of multidimensional correlations. This method can be applied to short or sparse time series and can be extended to cross-trial and cross-channel spectra if multiple short data segments of the same experiment are available. Together, this time-domain toolbox provides higher temporal resolution, increased frequency and phase coupling information, and it allows an easy and straightforward implementation of higher-order spectra across time compared with frequency-based methods such as the DFT and cross-spectral analysis.

Precise Time Delays from Strongly Gravitationally Lensed Type Ia Supernovae with Chromatically Microlensed Images

DOE PAGES

Goldstein, Daniel A.; Nugent, Peter E.; Kasen, Daniel N.; ...

2018-03-01

Time delays between the multiple images of strongly gravitationally lensed Type Ia supernovae (glSNe Ia) have the potential to deliver precise cosmological constraints, but the effects of microlensing on time delay extraction have not been studied in detail. Here we quantify the effect of microlensing on the glSN Ia yield of the Large Synoptic Survey Telescope (LSST) and the effect of microlensing on the precision and accuracy of time delays that can be extracted from LSST glSNe Ia. Microlensing has a negligible effect on the LSST glSN Ia yield, but it can be increased by a factor of ~2 overmore » previous predictions to 930 systems using a novel photometric identification technique based on spectral template fitting. Crucially, the microlensing of glSNe Ia is achromatic until three rest-frame weeks after the explosion, making the early-time color curves microlensing-insensitive time delay indicators. By fitting simulated flux and color observations of microlensed glSNe Ia with their underlying, unlensed spectral templates, we forecast the distribution of absolute time delay error due to microlensing for LSST, which is unbiased at the sub-percent level and peaked at 1% for color curve observations in the achromatic phase, while for light-curve observations it is comparable to state-of-the-art mass modeling uncertainties (4%). About 70% of LSST glSN Ia images should be discovered during the achromatic phase, indicating that microlensing time delay uncertainties can be minimized if prompt multicolor follow-up observations are obtained. Lastly, accounting for microlensing, the 1-2 day time delay on the recently discovered glSN Ia iPTF16geu can be measured to 40% precision, limiting its cosmological utility.« less

Precise Time Delays from Strongly Gravitationally Lensed Type Ia Supernovae with Chromatically Microlensed Images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldstein, Daniel A.; Nugent, Peter E.; Kasen, Daniel N.

Time delays between the multiple images of strongly gravitationally lensed Type Ia supernovae (glSNe Ia) have the potential to deliver precise cosmological constraints, but the effects of microlensing on time delay extraction have not been studied in detail. Here we quantify the effect of microlensing on the glSN Ia yield of the Large Synoptic Survey Telescope (LSST) and the effect of microlensing on the precision and accuracy of time delays that can be extracted from LSST glSNe Ia. Microlensing has a negligible effect on the LSST glSN Ia yield, but it can be increased by a factor of ~2 overmore » previous predictions to 930 systems using a novel photometric identification technique based on spectral template fitting. Crucially, the microlensing of glSNe Ia is achromatic until three rest-frame weeks after the explosion, making the early-time color curves microlensing-insensitive time delay indicators. By fitting simulated flux and color observations of microlensed glSNe Ia with their underlying, unlensed spectral templates, we forecast the distribution of absolute time delay error due to microlensing for LSST, which is unbiased at the sub-percent level and peaked at 1% for color curve observations in the achromatic phase, while for light-curve observations it is comparable to state-of-the-art mass modeling uncertainties (4%). About 70% of LSST glSN Ia images should be discovered during the achromatic phase, indicating that microlensing time delay uncertainties can be minimized if prompt multicolor follow-up observations are obtained. Lastly, accounting for microlensing, the 1-2 day time delay on the recently discovered glSN Ia iPTF16geu can be measured to 40% precision, limiting its cosmological utility.« less

Robust output feedback H∞ control for networked control systems based on the occurrence probabilities of time delays

NASA Astrophysics Data System (ADS)

Guo, Chenyu; Zhang, Weidong; Bao, Jie

2012-02-01

This article is concerned with the problem of robust H ∞ output feedback control for a kind of networked control systems with time-varying network-induced delays. Instead of using boundaries of time delays to represent all time delays, the occurrence probability of each time delay is considered in H∞ stability analysis and stabilisation. The problem addressed is the design of an output feedback controller such that, for all admissible uncertainties, the resulting closed-loop system is stochastically stable for the zero disturbance input and also simultaneously achieves a prescribed H∞ performance level. It is shown that less conservativeness is obtained. A set of linear matrix inequalities is given to solve the corresponding controller design problem. An example is provided to show the effectiveness and applicability of the proposed method.

Channel noise-induced temporal coherence transitions and synchronization transitions in adaptive neuronal networks with time delay

NASA Astrophysics Data System (ADS)

Gong, Yubing; Xie, Huijuan

2017-09-01

Using spike-timing-dependent plasticity (STDP), we study the effect of channel noise on temporal coherence and synchronization of adaptive scale-free Hodgkin-Huxley neuronal networks with time delay. It is found that the spiking regularity and spatial synchronization of the neurons intermittently increase and decrease as channel noise intensity is varied, exhibiting transitions of temporal coherence and synchronization. Moreover, this phenomenon depends on time delay, STDP, and network average degree. As time delay increases, the phenomenon is weakened, however, there are optimal STDP and network average degree by which the phenomenon becomes strongest. These results show that channel noise can intermittently enhance the temporal coherence and synchronization of the delayed adaptive neuronal networks. These findings provide a new insight into channel noise for the information processing and transmission in neural systems.

Finite-time stability of neutral-type neural networks with random time-varying delays

NASA Astrophysics Data System (ADS)

Ali, M. Syed; Saravanan, S.; Zhu, Quanxin

2017-11-01

This paper is devoted to the finite-time stability analysis of neutral-type neural networks with random time-varying delays. The randomly time-varying delays are characterised by Bernoulli stochastic variable. This result can be extended to analysis and design for neutral-type neural networks with random time-varying delays. On the basis of this paper, we constructed suitable Lyapunov-Krasovskii functional together and established a set of sufficient linear matrix inequalities approach to guarantee the finite-time stability of the system concerned. By employing the Jensen's inequality, free-weighting matrix method and Wirtinger's double integral inequality, the proposed conditions are derived and two numerical examples are addressed for the effectiveness of the developed techniques.

Finite-dimensional modeling of network-induced delays for real-time control systems

NASA Technical Reports Server (NTRS)

Ray, Asok; Halevi, Yoram

1988-01-01

In integrated control systems (ICS), a feedback loop is closed by the common communication channel, which multiplexes digital data from the sensor to the controller and from the controller to the actuator along with the data traffic from other control loops and management functions. Due to asynchronous time-division multiplexing in the network access protocols, time-varying delays are introduced in the control loop, which degrade the system dynamic performance and are a potential source of instability. The delayed control system is represented by a finite-dimensional, time-varying, discrete-time model which is less complex than the existing continuous-time models for time-varying delays; this approach allows for simpler schemes for analysis and simulation of the ICS.

Permutation entropy with vector embedding delays

NASA Astrophysics Data System (ADS)

Little, Douglas J.; Kane, Deb M.

2017-12-01

Permutation entropy (PE) is a statistic used widely for the detection of structure within a time series. Embedding delay times at which the PE is reduced are characteristic timescales for which such structure exists. Here, a generalized scheme is investigated where embedding delays are represented by vectors rather than scalars, permitting PE to be calculated over a (D -1 ) -dimensional space, where D is the embedding dimension. This scheme is applied to numerically generated noise, sine wave and logistic map series, and experimental data sets taken from a vertical-cavity surface emitting laser exhibiting temporally localized pulse structures within the round-trip time of the laser cavity. Results are visualized as PE maps as a function of embedding delay, with low PE values indicating combinations of embedding delays where correlation structure is present. It is demonstrated that vector embedding delays enable identification of structure that is ambiguous or masked, when the embedding delay is constrained to scalar form.

Estimation of time- and state-dependent delays and other parameters in functional differential equations

NASA Technical Reports Server (NTRS)

Murphy, K. A.

1988-01-01

A parameter estimation algorithm is developed which can be used to estimate unknown time- or state-dependent delays and other parameters (e.g., initial condition) appearing within a nonlinear nonautonomous functional differential equation. The original infinite dimensional differential equation is approximated using linear splines, which are allowed to move with the variable delay. The variable delays are approximated using linear splines as well. The approximation scheme produces a system of ordinary differential equations with nice computational properties. The unknown parameters are estimated within the approximating systems by minimizing a least-squares fit-to-data criterion. Convergence theorems are proved for time-dependent delays and state-dependent delays within two classes, which say essentially that fitting the data by using approximations will, in the limit, provide a fit to the data using the original system. Numerical test examples are presented which illustrate the method for all types of delay.

Estimation of time- and state-dependent delays and other parameters in functional differential equations

NASA Technical Reports Server (NTRS)

Murphy, K. A.

1990-01-01

A parameter estimation algorithm is developed which can be used to estimate unknown time- or state-dependent delays and other parameters (e.g., initial condition) appearing within a nonlinear nonautonomous functional differential equation. The original infinite dimensional differential equation is approximated using linear splines, which are allowed to move with the variable delay. The variable delays are approximated using linear splines as well. The approximation scheme produces a system of ordinary differential equations with nice computational properties. The unknown parameters are estimated within the approximating systems by minimizing a least-squares fit-to-data criterion. Convergence theorems are proved for time-dependent delays and state-dependent delays within two classes, which say essentially that fitting the data by using approximations will, in the limit, provide a fit to the data using the original system. Numerical test examples are presented which illustrate the method for all types of delay.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morishita, Sadaharu; Goto, Tetsuya; Nagase, Masaaki

Multiprocesses in a single plasma process chamber with high throughput require precise, sequential, high-speed alteration of partial pressures of multiple gas species. A conventional gas-distribution system cannot realize this because the system seriously overshoots gas pressure immediately following valve operation. Furthermore, chamber volume and conductance of gas piping between the system and chamber should both be considered because they delay the stabilizing time of gas pressure. Therefore, the authors proposed a new gas-distribution system without overshoot by controlling gas flow rate based on pressure measurement, as well as a method of pulse-controlled gas injection immediately following valve operation. Time variationmore » of measured partial pressure agrees well with a calculation based on an equivalent-circuit model that represents the chamber and gas piping between the system and chamber. Using pulse-controlled gas injection, the stabilizing time can be reduced drastically to 0.6 s for HBr added to pure Ar plasma, and 0.7 s for O{sub 2} added to Ar/HBr plasma; without the pulse control, the stabilizing times are 3 and 7 s, respectively. In the O{sub 2} addition case, rapid stabilization can be achieved during the period of line/space pattern etching of poly-Si on a thin SiO{sub 2} film. This occurs without anomalous etching of the underlying SiO{sub 2} film or the Si substrate near the sidewall, thus obtaining a wide process margin with high throughput.« less

Biological warfare warriors, secrecy and pure science in the Cold War: how to understand dialogue and the classifications of science.

PubMed

Bud, Robert

2014-01-01

This paper uses a case study from the Cold War to reflect on the meaning at the time of the term 'Pure Science'. In 1961, four senior scientists from Britain's biological warfare centre at Porton Down visited Moscow both attending an International Congress and visiting Russian microbiological and biochemical laboratories. The reports of the British scientists in talking about a limited range of topics encountered in the Soviet Union expressed qualities of openness, sociologists of the time associated with pure science. The paper reflects on the discourses of "Pure Science", secrecy and security in the Cold War. Using Bakhtin's approach, I suggest the cordial communication between scientists from opposing sides can be seen in terms of the performance, or speaking, of one language among several at their disposal. Pure science was the language they were allowed to share outside their institutions, and indeed political blocs.

How time delay and network design shape response patterns in biochemical negative feedback systems.

PubMed

Börsch, Anastasiya; Schaber, Jörg

2016-08-24

Negative feedback in combination with time delay can bring about both sustained oscillations and adaptive behaviour in cellular networks. Here, we study which design features of systems with delayed negative feedback shape characteristic response patterns with special emphasis on the role of time delay. To this end, we analyse generic two-dimensional delay differential equations describing the dynamics of biochemical signal-response networks. We investigate the influence of several design features on the stability of the model equilibrium, i.e., presence of auto-inhibition and/or mass conservation and the kind and/or strength of the delayed negative feedback. We show that auto-inhibition and mass conservation have a stabilizing effect, whereas increasing abruptness and decreasing feedback threshold have a de-stabilizing effect on the model equilibrium. Moreover, applying our theoretical analysis to the mammalian p53 system we show that an auto-inhibitory feedback can decouple period and amplitude of an oscillatory response, whereas the delayed feedback can not. Our theoretical framework provides insight into how time delay and design features of biochemical networks act together to elicit specific characteristic response patterns. Such insight is useful for constructing synthetic networks and controlling their behaviour in response to external stimulation.

Interesting and unusual clinical presentations in leprosy at a referral center.

PubMed

Tayshetye, Pritam U; Pai, Vivek V; Khanolkar, Subhash A; Rathod, Vikram; Ganapati, Ramaswamy

2013-10-01

Leprosy is a disease of declining global endemicity but is still an important health-care problem in India. Pure neural leprosy is an important subset of presentations of leprosy in India. Leprosy is a known disease of the skin and nerves, but cases of pure neural involvement are relatively less. We hereby present 10 cases of pure neural leprosy in which the diagnosis of leprosy was difficult with routine methods. The study was conducted at the main referral center and satellite clinics of our organization. A retrospective analysis of patient records for the last four years was undertaken to identify patients presenting with predominantly neurological manifestations and uncommon presentations including those without skin lesions. The medical records of the patients were used as source of data. All the patients were subjected to a detailed clinical examination and bacteriological examination with slit-skin smears. Investigations like nerve biopsy, electromyography, and nerve conduction studies were done in patients with diagnostic difficulties. Patients presented with neurological symptoms like paresthesias (60%), diminished sensations (40%), nonhealing ulcers (30%), and blisters (20%). All except one had thickened nerves on clinical examination. Slit-skin smear was negative in all but one patient. Nerve biopsy confirmed the diagnosis of leprosy in seven cases. Pure neural leprosy is difficult to diagnose with routine methods. The diagnosis should be considered, especially by neurologists and dermatologists, who are more likely to see such patients with predominant neural manifestations. The diagnosis should be confirmed with nerve biopsy to prevent delay in therapy and associated complications.

An adaptive robust controller for time delay maglev transportation systems

NASA Astrophysics Data System (ADS)

Milani, Reza Hamidi; Zarabadipour, Hassan; Shahnazi, Reza

2012-12-01

For engineering systems, uncertainties and time delays are two important issues that must be considered in control design. Uncertainties are often encountered in various dynamical systems due to modeling errors, measurement noises, linearization and approximations. Time delays have always been among the most difficult problems encountered in process control. In practical applications of feedback control, time delay arises frequently and can severely degrade closed-loop system performance and in some cases, drives the system to instability. Therefore, stability analysis and controller synthesis for uncertain nonlinear time-delay systems are important both in theory and in practice and many analytical techniques have been developed using delay-dependent Lyapunov function. In the past decade the magnetic and levitation (maglev) transportation system as a new system with high functionality has been the focus of numerous studies. However, maglev transportation systems are highly nonlinear and thus designing controller for those are challenging. The main topic of this paper is to design an adaptive robust controller for maglev transportation systems with time-delay, parametric uncertainties and external disturbances. In this paper, an adaptive robust control (ARC) is designed for this purpose. It should be noted that the adaptive gain is derived from Lyapunov-Krasovskii synthesis method, therefore asymptotic stability is guaranteed.

Effects of coffee intake and intraperitoneal caffeine on bone repair process--a histologic and histometric study.

PubMed

Macedo, Rander Moreira; Brentegani, Luiz Guilherme; Lacerda, Suzie Aparecida de

2015-01-01

Studies have suggested that caffeine acts on bone promoting an increase of calcium excretion, inhibition of osteoblast proliferation and delay in tissue repair process, raising the risk of fractures, osteoporosis, periodontal disease and affecting the success of bone reconstructive procedures. The aim of this study was to analyze histomorphometrically the process of alveolar bone healing after tooth extraction in rats subjected to daily intake of boiled coffee or intraperitoneal administration of caffeine. Forty-five male rats were divided according to the treatment in Control group (C); Coffee group (CO) - treated with coffee since birth; and Caffeine (CAF) - intraperitoneal injection of aqueous solution of caffeine 1.5% (0.2 mL/100g body weight) for 30 days. When weighing between 250-300 g they were anesthetized, subjected to extraction of the maxillary right incisor, and euthanized 7, 21 and 42 days after surgery for histological assessments of bone volume and the quality of formed bone in the dental socket. The qualitative results demonstrated larger amounts of blood clot and immature bone in animals under treatment of pure caffeine compared to coffee and control. Histometric analysis revealed that coffee treatment led to a 40% drop in bone formation, and caffeine a 60% drop in comparison to control animals (ANOVA p≤0.01). It was concluded that both the daily ingestion of coffee and the intraperitoneal administration of caffeine in rats delayed the alveolar bone reparative process after tooth extraction, and this effect was more aggressive when pure caffeine was used.

Stability and Hopf bifurcation of a delayed ratio-dependent predator-prey system

NASA Astrophysics Data System (ADS)

Wang, Wan-Yong; Pei, Li-Jun

2011-04-01

Since the ratio-dependent theory reflects the fact that predators must share and compete for food, it is suitable for describing the relationship between predators and their preys and has recently become a very important theory put forward by biologists. In order to investigate the dynamical relationship between predators and their preys, a so-called Michaelis-Menten ratio-dependent predator-prey model is studied in this paper with gestation time delays of predators and preys taken into consideration. The stability of the positive equilibrium is investigated by the Nyquist criteria, and the existence of the local Hopf bifurcation is analyzed by employing the theory of Hopf bifurcation. By means of the center manifold and the normal form theories, explicit formulae are derived to determine the stability, direction and other properties of bifurcating periodic solutions. The above theoretical results are validated by numerical simulations with the help of dynamical software WinPP. The results show that if both the gestation delays are small enough, their sizes will keep stable in the long run, but if the gestation delays of predators are big enough, their sizes will periodically fluctuate in the long term. In order to reveal the effects of time delays on the ratio-dependent predator-prey model, a ratio-dependent predator-prey model without time delays is considered. By Hurwitz criteria, the local stability of positive equilibrium of this model is investigated. The conditions under which the positive equilibrium is locally asymptotically stable are obtained. By comparing the results with those of the model with time delays, it shows that the dynamical behaviors of ratio-dependent predator-prey model with time delays are more complicated. Under the same conditions, namely, with the same parameters, the stability of positive equilibrium of ratio-dependent predator-prey model would change due to the introduction of gestation time delays for predators and preys. Moreover, with the variation of time delays, the positive equilibrium of the ratio-dependent predator-prey model subjects to Hopf bifurcation.

Profitless delays for extinction in nonautonomous Lotka-Volterra system

NASA Astrophysics Data System (ADS)

Liu, Shengqiang; Chen, Lansun

2001-12-01

We study the delayed periodic n-species Lotka-Voterra systems where the growth rate of each species is not always positive. The sufficient conditions for the extinction that are independent of the delays are obtained. Some known results are improved and generalized. Our results suggest that under some conditions, the introduction and the variance of the time delays can be both harmless and profitless. Discussion about the effect of time delays on the extinction of the system is also advanced.

Predicting fluctuations-caused regime shifts in a time delayed dynamics of an invading species

NASA Astrophysics Data System (ADS)

Xie, Qingshuang; Wang, Tonghuan; Zeng, Chunhua; Dong, Xiaohui; Guan, Lin

2018-03-01

In this paper, we investigate early warning signals (EWS) of regime shifts in a density-dependent invading population model with time delay, in which the population density is assumed to be disturbed by intrinsic and extrinsic fluctuations. It is shown that the time delay and noises can cause the regime shifts between low and high population density states. The regime shift time (RST) as a function of noise intensity exhibits a maximum, which identifies the signature of the noise-enhanced stability of the low density state, while the time delay weakens the stability of the low density state. Applying the Kramers time technique, we also discuss the intersection point of the RST between low and high population density states, i.e., a critical point in the RST is found. Therefore, the critical point may give an EWS of regime shifts from one alternative state to another one for the changes in the noise parameters and time delay.

Effects of the gaseous and liquid water content of the atmosphere on range delay and Doppler frequency

NASA Technical Reports Server (NTRS)

Flock, W. L.

1981-01-01

When high precision is required for range measurement on Earth space paths, it is necessary to correct as accurately as possible for excess range delays due to the dry air, water vapor, and liquid water content of the atmosphere. Calculations based on representative values of atmospheric parameters are useful for illustrating the order of magnitude of the expected delays. Range delay, time delay, and phase delay are simply and directly related. Doppler frequency variations or noise are proportional to the time rate of change of excess range delay. Tropospheric effects were examined as part of an overall consideration of the capability of precision two way ranging and Doppler systems.

The Effects of Time Delay and Increasing Prompt Hierarchy Strategies on the Acquisition of Purchasing Skills by Students with Severe Handicaps.

ERIC Educational Resources Information Center

McDonnell, John

1987-01-01

Two teaching strategies (constant time delay and increasing prompt hierarchy assistance) were compared in teaching four severely handicapped high school students to purchase snack items at a convenience store and fast food restaurant. Results indicated the time delay procedure was more effective. (DB)

Using Time Delay to Teach Literacy to Students with Severe Developmental Disabilities

ERIC Educational Resources Information Center

Browder, Diane; Ahlgrim-Delzell, Lynn; Spooner, Fred; Mims, Pamela J.; Baker, Joshua N.

2009-01-01

A review of the literature was conducted for articles published between 1975 and 2007 on the application of time delay as an instructional procedure to teach word and picture recognition to students with severe developmental disabilities in an effort to evaluate time delay as an evidence-based practice. A total of 30 experiments were analyzed…

The Effects of Aging on Time Reproduction in Delayed Free-Recall

ERIC Educational Resources Information Center

Rakitin, B.C.; Stern, Y.; Malapani, C.

2005-01-01

The experiments presented here demonstrate that normal aging amplifies differences in time production occurring in delayed free-recall testing. Experiment 1 compared the time production ability of two healthy aged groups as well as college-aged participants. During the test session, which followed a 24-h delay and omitted all feedback and examples…

Caregivers as Teachers: Using Constant Time Delay To Teach Adults How To Use Constant Time Delay.

ERIC Educational Resources Information Center

Wall, Maureen E.; Gast, David L.

1997-01-01

A study involving four caregivers evaluated the effectiveness of a systematic instructional procedure known as constant time delay (CTD) in teaching caregivers how to use CTD to teach their adolescent or adult children, siblings, or clients with disabilities, response chain skills. Results found the procedure to be effective. (CR)

Delay and déjà vu: timing and repetition increase the power of false evidence.

PubMed

Wright, Deborah S; Wade, Kimberley A; Watson, Derrick G

2013-08-01

False images and videos can induce people to believe in and remember events that never happened. Using a novel method, we examined whether the timing of false evidence would influence its effect (Experiment 1) and determined the relationship between timing and repetition (Experiment 2). Subjects completed a hazard perception driving test and were falsely accused of cheating. Some subjects were shown a fake video or photograph of the cheating either after a 9-min delay (Experiment 1) or more than once with or without a delay (Experiment 2). Subjects were more likely to falsely believe that they had cheated and to provide details about how the cheating happened when the false evidence was delayed or repeated-especially when repeated over time-relative to controls. The results show that even a strikingly short delay between an event and when false evidence is disclosed can distort people's beliefs and that repeating false evidence over a brief delay fosters false beliefs more so than without a delay. These findings have theoretical implications for metacognitive models of autobiographical memory and practical implications for police interrogations.

Effects of stochastic time-delayed feedback on a dynamical system modeling a chemical oscillator.

PubMed

González Ochoa, Héctor O; Perales, Gualberto Solís; Epstein, Irving R; Femat, Ricardo

2018-05-01

We examine how stochastic time-delayed negative feedback affects the dynamical behavior of a model oscillatory reaction. We apply constant and stochastic time-delayed negative feedbacks to a point Field-Körös-Noyes photosensitive oscillator and compare their effects. Negative feedback is applied in the form of simulated inhibitory electromagnetic radiation with an intensity proportional to the concentration of oxidized light-sensitive catalyst in the oscillator. We first characterize the system under nondelayed inhibitory feedback; then we explore and compare the effects of constant (deterministic) versus stochastic time-delayed feedback. We find that the oscillatory amplitude, frequency, and waveform are essentially preserved when low-dispersion stochastic delayed feedback is used, whereas small but measurable changes appear when a large dispersion is applied.

Using time-delay to improve social play skills with peers for children with autism.

PubMed

Liber, Daniella B; Frea, William D; Symon, Jennifer B G

2008-02-01

Interventions that teach social communication and play skills are crucial for the development of children with autism. The time delay procedure is effective in teaching language acquisition, social use of language, discrete behaviors, and chained activities to individuals with autism and developmental delays. In this study, three boys with autism, attending a non-public school, were taught play activities that combined a play sequence with requesting peer assistance, using a graduated time delay procedure. A multiple-baseline across subjects design demonstrated the success of this procedure to teach multiple-step social play sequences. Results indicated an additional gain of an increase in pretend play by one of the participants. Two also demonstrated a generalization of the skills learned through the time delay procedure.

Effects of stochastic time-delayed feedback on a dynamical system modeling a chemical oscillator

NASA Astrophysics Data System (ADS)

González Ochoa, Héctor O.; Perales, Gualberto Solís; Epstein, Irving R.; Femat, Ricardo

2018-05-01

We examine how stochastic time-delayed negative feedback affects the dynamical behavior of a model oscillatory reaction. We apply constant and stochastic time-delayed negative feedbacks to a point Field-Körös-Noyes photosensitive oscillator and compare their effects. Negative feedback is applied in the form of simulated inhibitory electromagnetic radiation with an intensity proportional to the concentration of oxidized light-sensitive catalyst in the oscillator. We first characterize the system under nondelayed inhibitory feedback; then we explore and compare the effects of constant (deterministic) versus stochastic time-delayed feedback. We find that the oscillatory amplitude, frequency, and waveform are essentially preserved when low-dispersion stochastic delayed feedback is used, whereas small but measurable changes appear when a large dispersion is applied.

Teleseismic P-wave Delay Time Tomography of the southern Superior Province and Midcontinent Rift System (MRS) Region

NASA Astrophysics Data System (ADS)

Bollmann, T. A.; van der Lee, S.; Frederiksen, A. W.; Wolin, E.; Aleqabi, G. I.; Revenaugh, J.; Wiens, D. A.; Darbyshire, F. A.

2014-12-01

The Superior Province Rifting Earthscope Experiment (SPREE) and the northern midwest footprint of USArray's Transportable Array recorded continuous ground motion for a period of 2.5 years. From around 400 M>5.5 teleseismic earthquakes recorded at 337 stations, we measured body wave delay times for 255 of these earthquakes. The P wave delays are accumulated over more than 45 thousand wave paths with turning points in the lower mantle. We combine these delay times with a similar number delay times used in previous tomographic studies of the study region. The latter delay times stem from fewer stations, including Polaris and CNSN stations, and nearly a thousand earthquakes. We combine these two sets of delay times to image the three-dimensional distribution of seismic velocity variations beneath the southern Superior Province and surrounding provinces. This combined data coverage is illustrated in the accompanying figure for a total number of 447 stations . The coverage and the combined delays form the best configuration yet to image the three-dimensional distribution of seismic P and S-wave velocity variations beneath the southern Superior and surrounding provinces. Closely spaced stations (~12 km) along and across the MRS provide higher resolving power for lithospheric structure beneath the rift system. Conforming to expectations that the entire region is underlain by thick, cool lithosphere, a mean delay of -.55 +/- .54 s. This is very similar to the mean delays -.6s +/- .37s measured for this region before 2012. Event corrections range from -.2 +/-.54 s and correlate with tectonics for 80% of the earthquakes. An inversion of these nearly one hundred thousand P and around thirty thousand S-wave delay times for high-resolution P and S-wave velocity structure, respectively, does not show structures that are obviously related to the crustal signature of the MRS. None of structures imaged, align with or have a similar shape to the high Mid-continent Gravity Anomaly (MGA). However, a low-velocity structure is imaged in the lithosphere just east of the MGA.

Superluminal and negative delay times in isotropic-anisotropic one-dimensional photonic crystal

NASA Astrophysics Data System (ADS)

Ouchani, N.; El Moussaouy, A.; Aynaou, H.; El Hassouani, Y.; El Boudouti, E. H.; Djafari-Rouhani, B.

2017-11-01

In this work, we investigate the possibility of superluminal and negative delay times for electromagnetic wave propagation in a linear and passive periodic structure consisting of alternating isotropic and anisotropic media. This phenomenon is due to the birefringence of the anisotropic layers of the structure. By adjusting the orientations of these layers, the delay times of transmitted waves can be controlled from subluminality to superluminality and vice versa. Numerical results indicate that the apparent superluminal propagation of light occurs inside the photonic band-gaps when the principal axes of the anisotropic layers are parallel or perpendicular to the fixed axes. For other orientations of these layers, tunneling and superluminal regimes appear inside the photonic bandgaps and in the allowed bands for frequencies close to the transmission minima. The effect of the number of unit cells of the photonic crystal structure on the propagation of light with superluminal and negative delay times is also investigated. We show that the structure exhibits the Hartman effect in which the tunneling delay time of the electromagnetic wave through the photonic band-gap of the structure converges asymptotically to a finite value with increasing the number of layers. The Green's function approach has been used to derive the transmission and reflection coefficients, the density of states, and the delay times of electromagnetic waves propagating through the structure. The control of the magnitude and the sign of the delay time of light propagation represent a key point in slow and fast light technologies. The proposed structure in this study represents a new system for controlling the delay times of wave propagation without a need of active or non-linear media as well as lossy or asymmetric periodic structures.

76 FR 1403 - Pure Magnesium From the People's Republic of China: Extension of Time Limit for the Preliminary...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-10

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-832] Pure Magnesium From the... order on pure magnesium from the People's Republic of China (``PRC''). See Antidumping or Countervailing... 23236 (May 3, 2010). Respondent, Tianjin Magnesium International Co., Ltd. (``TMI''), requested a review...

75 FR 2108 - Pure Magnesium from the People's Republic of China: Extension of Time for the Preliminary Results...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-14

... DEPARTMENT OF COMMERCE International Trade Administration [A-570-832] Pure Magnesium from the... order on pure magnesium from the People's Republic of China (``PRC''). See Antidumping or Countervailing... 20278 (May 1, 2009). Respondent, Tianjin Magnesium International Co., Ltd. (``TMI''), requested a review...

Physical-Chemical Characterization of Fruit Purees and Relationship with Sensory Analysis Carried out by Infants (12 to 24 mo).

PubMed

Inarejos-García, A M; Mancebo-Campos, V; Cañizares, P; Llanos, J

2015-05-01

Fruit purees are one of the foods earliest introduced foods in infants' diet during the complementary period. The rheological characteristics together with the sensory analysis are decisive factors for the acceptance of the food product by the infant. The sensory analysis of three commercial fruit purees (mixed fruits, pear, and plum) was studied by employing a new objective sensory parameter named as SAIR (Sensory Acceptance by Infants Ratio), which is the quotient between the percentage of puree consumed (%) by the time (seconds) throughout the storage time. In parallel, the rheological characteristics of the purees were analyzed in order to obtain a relationship with the SAIR parameter. It was proved that the best acceptance of the product (higher SAIR) was observed for such purees showing a lower apparent viscosity (lower consistency index, "K") and a less pseudoplastic behavior (higher flow behavior index, "n"). These results may help to obtain higher acceptance values based on easy obtainable and objective parameters. © 2015 Institute of Food Technologists®

Successful strategies for improving operating room efficiency at academic institutions.

PubMed

Overdyk, F J; Harvey, S C; Fishman, R L; Shippey, F

1998-04-01

In this prospective study, we evaluated the etiology of operating room (OR) delays in an academic institution, examined the impact of multidisciplinary strategies to improve OR efficiency, and established OR timing benchmarks for use in future OR efficiency studies. OR times and delay etiologies were collected for 94 cases during the initial phase of the study. Timing data and delay etiologies were analyzed, and 2 wk of multidisciplinary OR efficiency awareness education was conducted for the nursing, surgical, and anesthesia staff. After the education period, timing data were collected from 1787 cases, and monthly reports listing individual case delays and timing data were sent to the Chiefs of Service. For the first case of the day, patient in room, anesthesia ready, surgical preparation start, and procedure start time were significantly earlier (P < 0.01) in the posteducation period compared with the preeducation period, and the procedure start time for the first case of the day occurred, on average, 22 min earlier than all other procedures. For all cases combined, turnover time decreased, on average, by 16 min. Unavailability of surgeons, anesthesiologists, and residents decreased significantly (P < 0.05) as causes of OR delays. Anesthesia induction times were consistently longer for the vascular and cardiothoracic services, whereas surgical preparation time was increased for the neurosurgical and orthopedic services (P < 0.05). Identification of the etiology of OR inefficiency, combined with multidisciplinary awareness training and personal accountability, can improve OR efficiency. The time savings realized are probably most cost-effective when combined with more flexible OR staffing and improved OR scheduling. We achieved significant improvements in operating room efficiency by analyzing operating room data on causes of delays, devising strategies for minimizing the most common delays, and subsequently measuring delay data. Personal accountability, streamlining of procedures, interdisciplinary team work, and accurate data collection were all important contributors to improved efficiency.

Combined action of time-delay and colored cross-associated multiplicative and additive noises on stability and stochastic resonance for a stochastic metapopulation system

NASA Astrophysics Data System (ADS)

Wang, Kang-Kang; Zong, De-Cai; Wang, Ya-Jun; Li, Sheng-Hong

2016-05-01

In this paper, the transition between the stable state of a big density and the extinction state and stochastic resonance (SR) for a time-delayed metapopulation system disturbed by colored cross-correlated noises are investigated. By applying the fast descent method, the small time-delay approximation and McNamara and Wiesenfeld's SR theory, we investigate the impacts of time-delay, the multiplicative, additive noises and colored cross-correlated noise on the SNR and the shift between the two states of the system. Numerical results show that the multiplicative, additive noises and time-delay can all speed up the transition from the stable state to the extinction state, while the correlation noise and its correlation time can slow down the extinction process of the population system. With respect to SNR, the multiplicative noise always weakens the SR effect, while noise correlation time plays a dual role in motivating the SR phenomenon. Meanwhile, time-delay mainly plays a negative role in stimulating the SR phenomenon. Conversely, it could motivate the SR effect to increase the strength of the cross-correlation noise in the SNR-β plot, while the increase of additive noise intensity will firstly excite SR, and then suppress the SR effect.

A compensation controller based on a regional pole-assignment method for AMD control systems with a time-varying delay

NASA Astrophysics Data System (ADS)

Li, Zuohua; Chen, Chaojun; Teng, Jun; Wang, Ying

2018-04-01

Active mass damper/driver (AMD) control system has been proposed as an effective tool for high-rise buildings to resist strong dynamic loads. However, such disadvantage as time-varying delay in AMD control systems impedes their application in practices. Time-varying delay, which has an effect on the performance and stability of single-degree-of-freedom (SDOF) and multi-degree-of-freedom (MDOF) systems, is considered in the paper. In addition, a new time-delay compensation controller based on regional pole-assignment method is presented. To verify its effectiveness, the proposed method is applied to a numerical example of a ten-storey frame and an experiment of a single span four-storey steel frame. Both numerical and experimental results demonstrate that the proposed method can enhance the performances of an AMD control system with time-varying delays.

Back-propagation learning of infinite-dimensional dynamical systems.

PubMed

Tokuda, Isao; Tokunaga, Ryuji; Aihara, Kazuyuki

2003-10-01

This paper presents numerical studies of applying back-propagation learning to a delayed recurrent neural network (DRNN). The DRNN is a continuous-time recurrent neural network having time delayed feedbacks and the back-propagation learning is to teach spatio-temporal dynamics to the DRNN. Since the time-delays make the dynamics of the DRNN infinite-dimensional, the learning algorithm and the learning capability of the DRNN are different from those of the ordinary recurrent neural network (ORNN) having no time-delays. First, two types of learning algorithms are developed for a class of DRNNs. Then, using chaotic signals generated from the Mackey-Glass equation and the Rössler equations, learning capability of the DRNN is examined. Comparing the learning algorithms, learning capability, and robustness against noise of the DRNN with those of the ORNN and time delay neural network, advantages as well as disadvantages of the DRNN are investigated.

Spin-dependent delay time in ferromagnet/insulator/ferromagnet heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, ZhengWei; Zheng Shi, De; Lv, HouXiang

2014-07-07

We study theoretically spin-dependent group delay and dwell time in ferromagnet/insulator/ferromagnet (FM/I/FM) heterostructure. The results indicate that, when the electrons with different spin orientations tunnel through the FM/I/FM junction, the spin-up process and the spin-down process are separated on the time scales. As the self-interference delay has the spin-dependent features, the variations of spin-dependent dwell-time and spin-dependent group-delay time with the structure parameters appear different features, especially, in low incident energy range. These different features show up as that the group delay times for the spin-up electrons are always longer than those for spin-down electrons when the barrier height ormore » incident energy increase. In contrast, the dwell times for the spin-up electrons are longer (shorter) than those for spin-down electrons when the barrier heights (the incident energy) are under a certain value. When the barrier heights (the incident energy) exceed a certain value, the dwell times for the spin-up electrons turn out to be shorter (longer) than those for spin-down electrons. In addition, the group delay time and the dwell time for spin-up and down electrons also relies on the comparative direction of magnetization in two FM layers and tends to saturation with the thickness of the barrier.« less

Economy with the time delay of information flow—The stock market case

NASA Astrophysics Data System (ADS)

Miśkiewicz, Janusz

2012-02-01

Any decision process requires information about the past and present state of the system, but in an economy acquiring data and processing it is an expensive and time-consuming task. Therefore, the state of the system is often measured over some legal interval, analysed after the end of well defined time periods and the results announced much later before any strategic decision is envisaged. The various time delay roles have to be crucially examined. Here, a model of stock market coupled with an economy is investigated to emphasise the role of the time delay span on the information flow. It is shown that the larger the time delay the more important the collective behaviour of agents since one observes time oscillations in the absolute log-return autocorrelations.

Discovery of talatisamine as a novel specific blocker for the delayed rectifier K+ channels in rat hippocampal neurons.

PubMed

Song, M-K; Liu, H; Jiang, H-L; Yue, J-M; Hu, G-Y; Chen, H-Z

2008-08-13

Blocking specific K+ channels has been proposed as a promising strategy for the treatment of neurodegenerative diseases. Using a computational virtual screening approach and electrophysiological testing, we found four Aconitum alkaloids are potent blockers of the delayed rectifier K+ channel in rat hippocampal neurons. In the present study, we first tested the action of the four alkaloids on the voltage-gated K+, Na+ and Ca2+ currents in rat hippocampal neurons, and then identified that talatisamine is a specific blocker for the delayed rectifier K+ channel. External application of talatisamine reversibly inhibited the delayed rectifier K+ current (IK) with an IC50 value of 146.0+/-5.8 microM in a voltage-dependent manner, but exhibited very slight blocking effect on the voltage-gated Na+ and Ca2+ currents even at the high concentration of 1-3 mM. Moreover, talatisamine exerted a significant hyperpolarizing shift of the steady-state activation, but did not influence the steady state inactivation of IK and its recovery from inactivation, suggesting that talatisamine had no allosteric action on IK channel and was a pure blocker binding to the external pore entry of the channel. Our present study made the first discovery of potent and specific IK channel blocker from Aconitum alkaloids. It has been argued that suppressing K+ efflux by blocking IK channel may be favorable for Alzheimer's disease therapy. Talatisamine can therefore be considered as a leading compound worthy of further investigations.

Free-running waveform characterization using a delay-time tunable laser based delay-line-free electro-optic sampling oscilloscope

NASA Astrophysics Data System (ADS)

Lin, Gong-Ru

2002-12-01

We develop a delay-line-free and frequency traceable electro-optic sampling oscilloscope by use of a digital phase-locked loop phase shifter (PLL-PS) controlled delay-time-tunable gain-switched laser diode (GSLD). The home-made voltage-controllable PLL-PS exhibits a linear transfer function with ultra-wide phase shifting range of ±350° and tuning error of <±5%, which benefits the advantages of frequency tracking to free-running signals with suppressed timing-jitter. The maximum delay-time of PLL-PS controlled GSLD is up to 1.95 periods by changing the controlling voltage ( VREF) from -3.5 to 3.5 V, which corresponds to 3.9 ns at repetition frequency of 500 MHz. The tuning responsivity and resolution are about 0.56 ns/V and 0.15˜0.2 ps, respectively. The maximum delay-time switching bandwidth of 100 Hz is determined under the control of a saw-tooth modulated VREF function. The waveform sampling of microwave PECL signals generated from a free-running digital frequency divider is performed with acceptable measuring deviation.

Existence and Stability of Traveling Waves for Degenerate Reaction-Diffusion Equation with Time Delay

NASA Astrophysics Data System (ADS)

Huang, Rui; Jin, Chunhua; Mei, Ming; Yin, Jingxue

2018-01-01

This paper deals with the existence and stability of traveling wave solutions for a degenerate reaction-diffusion equation with time delay. The degeneracy of spatial diffusion together with the effect of time delay causes us the essential difficulty for the existence of the traveling waves and their stabilities. In order to treat this case, we first show the existence of smooth- and sharp-type traveling wave solutions in the case of c≥c^* for the degenerate reaction-diffusion equation without delay, where c^*>0 is the critical wave speed of smooth traveling waves. Then, as a small perturbation, we obtain the existence of the smooth non-critical traveling waves for the degenerate diffusion equation with small time delay τ >0 . Furthermore, we prove the global existence and uniqueness of C^{α ,β } -solution to the time-delayed degenerate reaction-diffusion equation via compactness analysis. Finally, by the weighted energy method, we prove that the smooth non-critical traveling wave is globally stable in the weighted L^1 -space. The exponential convergence rate is also derived.

Existence and Stability of Traveling Waves for Degenerate Reaction-Diffusion Equation with Time Delay

NASA Astrophysics Data System (ADS)

Huang, Rui; Jin, Chunhua; Mei, Ming; Yin, Jingxue

2018-06-01

This paper deals with the existence and stability of traveling wave solutions for a degenerate reaction-diffusion equation with time delay. The degeneracy of spatial diffusion together with the effect of time delay causes us the essential difficulty for the existence of the traveling waves and their stabilities. In order to treat this case, we first show the existence of smooth- and sharp-type traveling wave solutions in the case of c≥c^* for the degenerate reaction-diffusion equation without delay, where c^*>0 is the critical wave speed of smooth traveling waves. Then, as a small perturbation, we obtain the existence of the smooth non-critical traveling waves for the degenerate diffusion equation with small time delay τ >0. Furthermore, we prove the global existence and uniqueness of C^{α ,β }-solution to the time-delayed degenerate reaction-diffusion equation via compactness analysis. Finally, by the weighted energy method, we prove that the smooth non-critical traveling wave is globally stable in the weighted L^1-space. The exponential convergence rate is also derived.

SU-E-J-141: Assessment of the Magnitude and Impact of Trigger Delay in Respiratory Triggered Real-Time Imaging during Radiotherapy.

PubMed

Duan, J; Shen, S; Popple, R; Wu, X; Cardan, R; Brezovich, I

2012-06-01

To assess the trigger delay in respiratory triggered real-time imaging and its impact on image guided radiotherapy (IGRT) with Varian TrueBeam System. A sinusoidal motion phantom with 2cm motion amplitude was used. The trigger delay was determined directly with video image, and indirectly by the distance between expected and actual triggering phantom positions. For the direct method, a fluorescent screen was placed on the phantom to visualize the x-ray. The motion of the screen was recorded at 60 frames/second. The number of frames between the time when the phantom reached expected triggering position and the time when the screen was illuminated by the x-ray was used to determine the trigger delay. In the indirect method, triggered kV x-ray images were acquired in real-time during 'treatment' with triggers set at 25% and 75% respiratory phases where the phantom moved at the maximum speed. 39-40 triggered images were acquired continuously in each series. The distance between the expected and actual triggering points, d, was measured on the images to determine the delay time t by d=Asin(wt), where w=2π/T, T=period and A=amplitude. Motion periods of 2s and 4s were used in the measurement. The trigger delay time determined with direct video imaging was 125ms (7.5 video frames). The average distance between the expected and actual triggering positions determined by the indirect method was 3.93±0.74mm for T=4s and 7.02±1.25mm for T=2s, yielding mean trigger delay times of 126±24ms and 120±22ms, respectively. Although the mean over-travel distance is significant at 25% and 75% phases, clinically, the target over-travel resulted from the trigger delay at the end of expiration (50% phase) is negligibly small(< 0.5mm). The trigger delay in respiration-triggered imaging is in the range of 120-126ms. This delay has negligible clinical effect on gated IGRT. © 2012 American Association of Physicists in Medicine.

Discrete-time bidirectional associative memory neural networks with variable delays

NASA Astrophysics Data System (ADS)

Liang, variable delays [rapid communication] J.; Cao, J.; Ho, D. W. C.

2005-02-01

Based on the linear matrix inequality (LMI), some sufficient conditions are presented in this Letter for the existence, uniqueness and global exponential stability of the equilibrium point of discrete-time bidirectional associative memory (BAM) neural networks with variable delays. Some of the stability criteria obtained in this Letter are delay-dependent, and some of them are delay-independent, they are less conservative than the ones reported so far in the literature. Furthermore, the results provide one more set of easily verified criteria for determining the exponential stability of discrete-time BAM neural networks.

Time Delay in the Kuramoto Model of Coupled Oscillators

NASA Astrophysics Data System (ADS)

Yeung, M. K. Stephen; Strogatz, Steven H.

1999-01-01

We generalize the Kuramoto model of coupled oscillators to allow time-delayed interactions. New phenomena include bistability between synchronized and incoherent states, and unsteady solutions with time-dependent order parameters. We derive exact formulas for the stability boundaries of the incoherent and synchronized states, as a function of the delay, in the special case where the oscillators are identical. The experimental implications of the model are discussed for populations of chirping crickets, where the finite speed of sound causes communication delays, and for physical systems such as coupled phase-locked loops or lasers.

Reading Comprehension in Quiet and in Noise: Effects on Immediate and Delayed Recall in Relation to Tinnitus and High-Frequency Hearing Thresholds.

PubMed

Brännström, K Jonas; Waechter, Sebastian

2018-06-01

A common complaint by people with tinnitus is that they experience that the tinnitus causes attention and concentration problems. Previous studies have examined how tinnitus influences cognitive performance on short and intensive cognitive tasks but without proper control of hearing status. To examine the impact tinnitus and high-frequency hearing thresholds have on reading comprehension in quiet and in background noise. A between-group design with matched control participants. One group of participants with tinnitus (n = 20) and an age and gender matched control group without tinnitus (n = 20) participated. Both groups had normal hearing thresholds (20 dB HL at frequencies 0.125 to 8 kHz). Measurements were made assessing hearing thresholds and immediate and delayed recall using a reading comprehension test in quiet and in noise. All participants completed the Swedish version of the Hospital Anxiety and Depression Scale, and participants with tinnitus also completed the Tinnitus Questionnaire. The groups did not differ in immediate nor delayed recall. Accounting for the effect of age, a significant positive correlation was found between best ear high-frequency pure tone average (HF-PTA; 10000, 12500, and 14000 Hz) and the difference score between immediate and delayed recall in noise. Tinnitus seems to have no effect on immediate and delayed recall in quiet or in background noise when hearing status is controlled for. The detrimental effect of background noise on the processes utilized for efficient encoding into long-term memory is larger in participants with better HF-PTA. More specifically, when reading in noise, participants with better HF-PTA seem to recall less information than participants with poorer HF-PTA. American Academy of Audiology.

Surface acoustic wave devices as passive buried sensors

NASA Astrophysics Data System (ADS)

Friedt, J.-M.; Rétornaz, T.; Alzuaga, S.; Baron, T.; Martin, G.; Laroche, T.; Ballandras, S.; Griselin, M.; Simonnet, J.-P.

2011-02-01

Surface acoustic wave (SAW) devices are currently used as passive remote-controlled sensors for measuring various physical quantities through a wireless link. Among the two main classes of designs—resonator and delay line—the former has the advantage of providing narrow-band spectrum informations and hence appears compatible with an interrogation strategy complying with Industry-Scientific-Medical regulations in radio-frequency (rf) bands centered around 434, 866, or 915 MHz. Delay-line based sensors require larger bandwidths as they consists of a few interdigitated electrodes excited by short rf pulses with large instantaneous energy and short response delays but is compatible with existing equipment such as ground penetrating radar (GPR). We here demonstrate the measurement of temperature using the two configurations, particularly for long term monitoring using sensors buried in soil. Although we have demonstrated long term stability and robustness of packaged resonators and signal to noise ratio compatible with the expected application, the interrogation range (maximum 80 cm) is insufficient for most geology or geophysical purposes. We then focus on the use of delay lines, as the corresponding interrogation method is similar to the one used by GPR which allows for rf penetration distances ranging from a few meters to tens of meters and which operates in the lower rf range, depending on soil water content, permittivity, and conductivity. Assuming propagation losses in a pure dielectric medium with negligible conductivity (snow or ice), an interrogation distance of about 40 m is predicted, which overcomes the observed limits met when using interrogation methods specifically developed for wireless SAW sensors, and could partly comply with the above-mentioned applications. Although quite optimistic, this estimate is consistent with the signal to noise ratio observed during an experimental demonstration of the interrogation of a delay line buried at a depth of 5 m in snow.

Probability-based constrained MPC for structured uncertain systems with state and random input delays

NASA Astrophysics Data System (ADS)

Lu, Jianbo; Li, Dewei; Xi, Yugeng

2013-07-01

This article is concerned with probability-based constrained model predictive control (MPC) for systems with both structured uncertainties and time delays, where a random input delay and multiple fixed state delays are included. The process of input delay is governed by a discrete-time finite-state Markov chain. By invoking an appropriate augmented state, the system is transformed into a standard structured uncertain time-delay Markov jump linear system (MJLS). For the resulting system, a multi-step feedback control law is utilised to minimise an upper bound on the expected value of performance objective. The proposed design has been proved to stabilise the closed-loop system in the mean square sense and to guarantee constraints on control inputs and system states. Finally, a numerical example is given to illustrate the proposed results.

Methodology for Analysis, Modeling and Simulation of Airport Gate-waiting Delays

NASA Astrophysics Data System (ADS)

Wang, Jianfeng

This dissertation presents methodologies to estimate gate-waiting delays from historical data, to identify gate-waiting-delay functional causes in major U.S. airports, and to evaluate the impact of gate operation disruptions and mitigation strategies on gate-waiting delay. Airport gates are a resource of congestion in the air transportation system. When an arriving flight cannot pull into its gate, the delay it experiences is called gate-waiting delay. Some possible reasons for gate-waiting delay are: the gate is occupied, gate staff or equipment is unavailable, the weather prevents the use of the gate (e.g. lightning), or the airline has a preferred gate assignment. Gate-waiting delays potentially stay with the aircraft throughout the day (unless they are absorbed), adding costs to passengers and the airlines. As the volume of flights increases, ensuring that airport gates do not become a choke point of the system is critical. The first part of the dissertation presents a methodology for estimating gate-waiting delays based on historical, publicly available sources. Analysis of gate-waiting delays at major U.S. airports in the summer of 2007 identifies the following. (i) Gate-waiting delay is not a significant problem on majority of days; however, the worst delay days (e.g. 4% of the days at LGA) are extreme outliers. (ii) The Atlanta International Airport (ATL), the John F. Kennedy International Airport (JFK), the Dallas/Fort Worth International Airport (DFW) and the Philadelphia International Airport (PHL) experience the highest gate-waiting delays among major U.S. airports. (iii) There is a significant gate-waiting-delay difference between airlines due to a disproportional gate allocation. (iv) Gate-waiting delay is sensitive to time of a day and schedule peaks. According to basic principles of queueing theory, gate-waiting delay can be attributed to over-scheduling, higher-than-scheduled arrival rate, longer-than-scheduled gate-occupancy time, and reduced gate availability. Analysis of the worst days at six major airports in the summer of 2007 indicates that major gate-waiting delays are primarily due to operational disruptions---specifically, extended gate occupancy time, reduced gate availability and higher-than-scheduled arrival rate (usually due to arrival delay). Major gate-waiting delays are not a result of over-scheduling. The second part of this dissertation presents a simulation model to evaluate the impact of gate operational disruptions and gate-waiting-delay mitigation strategies, including building new gates, implementing common gates, using overnight off-gate parking and adopting self-docking gates. Simulation results show the following effects of disruptions: (i) The impact of arrival delay in a time window (e.g. 7 pm to 9 pm) on gate-waiting delay is bounded. (ii) The impact of longer-than-scheduled gate-occupancy times in a time window on gate-waiting delay can be unbounded and gate-waiting delay can increase linearly as the disruption level increases. (iii) Small reductions in gate availability have a small impact on gate-waiting delay due to slack gate capacity, while larger reductions have a non-linear impact as slack gate capacity is used up. Simulation results show the following effects of mitigation strategies: (i) Implementing common gates is an effective mitigation strategy, especially for airports with a flight schedule not dominated by one carrier, such as LGA. (ii) The overnight off-gate rule is effective in mitigating gate-waiting delay for flights stranded overnight following departure cancellations. This is especially true at airports where the gate utilization is at maximum overnight, such as LGA and DFW. The overnight off-gate rule can also be very effective to mitigate gate-waiting delay due to operational disruptions in evenings. (iii) Self-docking gates are effective in mitigating gate-waiting delay due to reduced gate availability.

Time delays, population, and economic development

NASA Astrophysics Data System (ADS)

Gori, Luca; Guerrini, Luca; Sodini, Mauro

2018-05-01

This research develops an augmented Solow model with population dynamics and time delays. The model produces either a single stationary state or multiple stationary states (able to characterise different development regimes). The existence of time delays may cause persistent fluctuations in both economic and demographic variables. In addition, the work identifies in a simple way the reasons why economics affects demographics and vice versa.

Relations between Self Regulation, Future Time Perspective and the Delay of Gratification in University Students

ERIC Educational Resources Information Center

Avci, Suleyman

2013-01-01

The present study was conducted on 508 (331 female, 144 male) first grade university students in order to investigate the relations between self regulation, the future time perspectives, and the delay of gratification in the academic field. A future time perspective scale, an academic delay of gratification scale and a motivational strategies for…

Procedural Adaptations for Use of Constant Time Delay to Teach Highly Motivating Words to Beginning Braille Readers

ERIC Educational Resources Information Center

Ivy, Sarah E.; Guerra, Jennifer A.; Hatton, Deborah D.

2017-01-01

Introduction: Constant time delay is an evidence-based practice to teach sight word recognition to students with a variety of disabilities. To date, two studies have documented its effectiveness for teaching braille. Methods: Using a multiple-baseline design, we evaluated the effectiveness of constant time delay to teach highly motivating words to…

An Evaluation of Constant Time Delay and Simultaneous Prompting Procedures in Skill Acquisition for Young Children with Autism

ERIC Educational Resources Information Center

Brandt, Julie A. Ackerlund; Weinkauf, Sara; Zeug, Nicole; Klatt, Kevin P.

2016-01-01

Previous research has shown that various prompting procedures are effective in teaching skills to children and adults with developmental disabilities. Simultaneous prompting includes proving a prompt immediately following an instruction; whereas constant time-delay procedures include a set time delay (i.e., 5 s or 10 s) prior to delivering a…

A dynamic IS-LM business cycle model with two time delays in capital accumulation equation

NASA Astrophysics Data System (ADS)

Zhou, Lujun; Li, Yaqiong

2009-06-01

In this paper, we analyze a augmented IS-LM business cycle model with the capital accumulation equation that two time delays are considered in investment processes according to Kalecki's idea. Applying stability switch criteria and Hopf bifurcation theory, we prove that time delays cause the equilibrium to lose or gain stability and Hopf bifurcation occurs.

Wigner-Eisenbud-Smith photoionization time delay due to autoioinization resonances

NASA Astrophysics Data System (ADS)

Deshmukh, P. C.; Kumar, A.; Varma, H. R.; Banerjee, S.; Manson, Steven T.; Dolmatov, V. K.; Kheifets, A. S.

2018-03-01

An empirical ansatz for the complex photoionization amplitude and Wigner-Eisenbud-Smith time delay in the vicinity of a Fano autoionization resonance are proposed to evaluate and interpret the time delay in the resonant region. The utility of this expression is evaluated in comparison with accurate numerical calculations employing the ab initio relativistic random phase approximation and relativistic multichannel quantum defect theory. The indisputably good qualitative agreement (and semiquantitative agreement) between corresponding results of the proposed model and results produced by the ab initio theories proves the usability of the model. In addition, the phenomenology of the time delay in the vicinity of multichannel autoionizing resonances is detailed.

Single-shot transient absorption spectroscopy with a 45  ps pump-probe time delay range.

PubMed

Wilson, Kelly S; Wong, Cathy Y

2018-02-01

We report a single-shot transient absorption apparatus that successfully uses a tilted pump pulse to spatially encode a 45 ps pump-probe time delay. The time delay range is significantly improved over other reported instruments by using a spatial light modulator to flatten the intensity of the excitation field at the sample position. The full time delay range of the instrument is demonstrated by measuring a long-lived dye. A signal-to-noise ratio of >35 is attained in 8 s. This advance will enable the measurement of excited state dynamics of systems that are not at structural equilibrium.

Measurements and interpretation of shock tube ignition delay times in highly CO 2 diluted mixtures using multiple diagnostics

DOE PAGES

Vasu, Subith S.; Pryor, Owen; Barak, Samuel; ...

2017-03-12

Common definitions for ignition delay time are often hard to determine due to the issue of bifurcation and other non-idealities that result from high levels of CO 2 addition. Using high-speed camera imagery in comparison with more standard methods (e.g., pressure, emission, and laser absorption spectroscopy) to measure the ignition delay time, the effect of bifurcation has been examined in this study. Experiments were performed at pressures between 0.6 and 1.2 atm for temperatures between 1650 and 2040 K. The equivalence ratio for all experiments was kept at a constant value of 1 with methane as the fuel. The COmore » 2 mole fraction was varied between a value of X CO2 = 0.00 to 0.895. The ignition delay time was determined from three different measurements at the sidewall: broadband chemiluminescent emission captured via a photodetector, CH 4 concentrations determined using a distributed feedback interband cascade laser centered at 3403.4 nm, and pressure recorded via a dynamic Kistler type transducer. All methods for the ignition delay time were compared to high-speed camera images taken of the axial cross-section during combustion. Methane time-histories and the methane decay times were also measured using the laser. It was determined that the flame could be correlated to the ignition delay time measured at the side wall but that the flame as captured by the camera was not homogeneous as assumed in typical shock tube experiments. The bifurcation of the shock wave resulted in smaller flames with large boundary layers and that the flame could be as small as 30% of the cross-sectional area of the shock tube at the highest levels of CO 2 dilution. Here, comparisons between the camera images and the different ignition delay time methods show that care must be taken in interpreting traditional ignition delay data for experiments with large bifurcation effects as different methods in measuring the ignition delay time could result in different interpretations of kinetic mechanisms and impede the development of future mechanisms.« less

Measurements and interpretation of shock tube ignition delay times in highly CO 2 diluted mixtures using multiple diagnostics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vasu, Subith S.; Pryor, Owen; Barak, Samuel

Common definitions for ignition delay time are often hard to determine due to the issue of bifurcation and other non-idealities that result from high levels of CO 2 addition. Using high-speed camera imagery in comparison with more standard methods (e.g., pressure, emission, and laser absorption spectroscopy) to measure the ignition delay time, the effect of bifurcation has been examined in this study. Experiments were performed at pressures between 0.6 and 1.2 atm for temperatures between 1650 and 2040 K. The equivalence ratio for all experiments was kept at a constant value of 1 with methane as the fuel. The COmore » 2 mole fraction was varied between a value of X CO2 = 0.00 to 0.895. The ignition delay time was determined from three different measurements at the sidewall: broadband chemiluminescent emission captured via a photodetector, CH 4 concentrations determined using a distributed feedback interband cascade laser centered at 3403.4 nm, and pressure recorded via a dynamic Kistler type transducer. All methods for the ignition delay time were compared to high-speed camera images taken of the axial cross-section during combustion. Methane time-histories and the methane decay times were also measured using the laser. It was determined that the flame could be correlated to the ignition delay time measured at the side wall but that the flame as captured by the camera was not homogeneous as assumed in typical shock tube experiments. The bifurcation of the shock wave resulted in smaller flames with large boundary layers and that the flame could be as small as 30% of the cross-sectional area of the shock tube at the highest levels of CO 2 dilution. Here, comparisons between the camera images and the different ignition delay time methods show that care must be taken in interpreting traditional ignition delay data for experiments with large bifurcation effects as different methods in measuring the ignition delay time could result in different interpretations of kinetic mechanisms and impede the development of future mechanisms.« less

Coherent Pattern Prediction in Swarms of Delay-Coupled Agents

NASA Astrophysics Data System (ADS)

Mier-Y-Teran-Romero, Luis; Forgoston, Eric; Scwartz, Ira

2013-03-01

We consider a general swarm model of self-propelling particles interacting through a pairwise potential in the presence of a fixed communication time delay. Previous work has shown that swarms with communication time delays and noise may display pattern transitions that depend on the size of the coupling amplitude. We extend these results by completely unfolding the bifurcation structure of the mean field approximation. Our analysis reveals a direct correspondence between the different dynamical behaviors found in different regions of the coupling-time delay plane with the different classes of simulated coherent swarm patterns. We derive the spatio-temporal scales of the swarm structures, and also demonstrate how the complicated interplay of coupling strength, time delay, noise intensity, and choice of initial conditions can affect the swarm. In addition, when adding noise to the system, we find that for sufficiently large values of the coupling strength and/or the time delay, there is a noise intensity threshold that forces a transition of the swarm from a misaligned state into an aligned state. We show that this alignment transition exhibits hysteresis when the noise intensity is taken to be time dependent. Office of Naval Research, NIH (LMR and IBS) and NRL (EF)

Laser-induced periodic surface structures on 6H-SiC single crystals using temporally delayed femtosecond laser double-pulse trains

NASA Astrophysics Data System (ADS)

Song, Juan; Tao, Wenjun; Song, Hui; Gong, Min; Ma, Guohong; Dai, Ye; Zhao, Quanzhong; Qiu, Jianrong

2016-04-01

In this paper, a time-delay-adjustable double-pulse train with 800-nm wavelength, 200-fs pulse duration and a repetition rate of 1 kHz, produced by a collinear two-beam optical system like a Mach-Zehnder interferometer, was employed for irradiation of 6H-SiC crystal. The dependence of the induced structures on time delay of double-pulse train for parallel-polarization configuration was studied. The results show that as the time delay of collinear parallel-polarization dual-pulse train increased, the induced near-subwavelength ripples (NSWRs) turn from irregular rippled pattern to regularly periodic pattern and have their grooves much deepened. The characteristics timescale for this transition is about 6.24 ps. Besides, the areas of NSWR were found to decay exponentially for time delay from 0 to 1.24 ps and then slowly increase for time delay from 1.24 to 14.24 ps. Analysis shows that multiphoton ionization effect, grating-assisted surface plasmon coupling effect, and timely intervene of second pulse in a certain physical stage experienced by 6H-SiC excited upon first pulse irradiation may contribute to the transition of morphology details.

Size reduction techniques for vital compliant VHDL simulation models

DOEpatents

Rich, Marvin J.; Misra, Ashutosh

2006-08-01

A method and system select delay values from a VHDL standard delay file that correspond to an instance of a logic gate in a logic model. Then the system collects all the delay values of the selected instance and builds super generics for the rise-time and the fall-time of the selected instance. Then, the system repeats this process for every delay value in the standard delay file (310) that correspond to every instance of every logic gate in the logic model. The system then outputs a reduced size standard delay file (314) containing the super generics for every instance of every logic gate in the logic model.

Qualitative analysis of Cohen-Grossberg neural networks with multiple delays

NASA Astrophysics Data System (ADS)

Ye, Hui; Michel, Anthony N.; Wang, Kaining

1995-03-01

It is well known that a class of artificial neural networks with symmetric interconnections and without transmission delays, known as Cohen-Grossberg neural networks, possesses global stability (i.e., all trajectories tend to some equilibrium). We demonstrate in the present paper that many of the qualitative properties of Cohen-Grossberg networks will not be affected by the introduction of sufficiently small delays. Specifically, we establish some bound conditions for the time delays under which a given Cohen-Grossberg network with multiple delays is globally stable and possesses the same asymptotically stable equilibria as the corresponding network without delays. An effective method of determining the asymptotic stability of an equilibrium of a Cohen-Grossberg network with multiple delays is also presented. The present results are motivated by some of the authors earlier work [Phys. Rev. E 50, 4206 (1994)] and by some of the work of Marcus and Westervelt [Phys. Rev. A 39, 347 (1989)]. These works address qualitative analyses of Hopfield neural networks with one time delay. The present work generalizes these results to Cohen-Grossberg neural networks with multiple time delays. Hopfield neural networks constitute special cases of Cohen-Grossberg neural networks.

Adaptive Fading Memory H∞ Filter Design for Compensation of Delayed Components in Self Powered Flux Detectors

NASA Astrophysics Data System (ADS)

Tamboli, Prakash Kumar; Duttagupta, Siddhartha P.; Roy, Kallol

2015-08-01

The paper deals with dynamic compensation of delayed Self Powered Flux Detectors (SPFDs) using discrete time H∞ filtering method for improving the response of SPFDs with significant delayed components such as Platinum and Vanadium SPFD. We also present a comparative study between the Linear Matrix Inequality (LMI) based H∞ filtering and Algebraic Riccati Equation (ARE) based Kalman filtering methods with respect to their delay compensation capabilities. Finally an improved recursive H∞ filter based on the adaptive fading memory technique is proposed which provides an improved performance over existing methods. The existing delay compensation algorithms do not account for the rate of change in the signal for determining the filter gain and therefore add significant noise during the delay compensation process. The proposed adaptive fading memory H∞ filter minimizes the overall noise very effectively at the same time keeps the response time at minimum values. The recursive algorithm is easy to implement in real time as compared to the LMI (or ARE) based solutions.

Synchronization of generalized reaction-diffusion neural networks with time-varying delays based on general integral inequalities and sampled-data control approach.

PubMed

Dharani, S; Rakkiyappan, R; Cao, Jinde; Alsaedi, Ahmed

2017-08-01

This paper explores the problem of synchronization of a class of generalized reaction-diffusion neural networks with mixed time-varying delays. The mixed time-varying delays under consideration comprise of both discrete and distributed delays. Due to the development and merits of digital controllers, sampled-data control is a natural choice to establish synchronization in continuous-time systems. Using a newly introduced integral inequality, less conservative synchronization criteria that assure the global asymptotic synchronization of the considered generalized reaction-diffusion neural network and mixed delays are established in terms of linear matrix inequalities (LMIs). The obtained easy-to-test LMI-based synchronization criteria depends on the delay bounds in addition to the reaction-diffusion terms, which is more practicable. Upon solving these LMIs by using Matlab LMI control toolbox, a desired sampled-data controller gain can be acuqired without any difficulty. Finally, numerical examples are exploited to express the validity of the derived LMI-based synchronization criteria.

Detection of time delays and directional interactions based on time series from complex dynamical systems

NASA Astrophysics Data System (ADS)

Ma, Huanfei; Leng, Siyang; Tao, Chenyang; Ying, Xiong; Kurths, Jürgen; Lai, Ying-Cheng; Lin, Wei

2017-07-01

Data-based and model-free accurate identification of intrinsic time delays and directional interactions is an extremely challenging problem in complex dynamical systems and their networks reconstruction. A model-free method with new scores is proposed to be generally capable of detecting single, multiple, and distributed time delays. The method is applicable not only to mutually interacting dynamical variables but also to self-interacting variables in a time-delayed feedback loop. Validation of the method is carried out using physical, biological, and ecological models and real data sets. Especially, applying the method to air pollution data and hospital admission records of cardiovascular diseases in Hong Kong reveals the major air pollutants as a cause of the diseases and, more importantly, it uncovers a hidden time delay (about 30-40 days) in the causal influence that previous studies failed to detect. The proposed method is expected to be universally applicable to ascertaining and quantifying subtle interactions (e.g., causation) in complex systems arising from a broad range of disciplines.

Fine Output Voltage Control Method considering Time-Delay of Digital Inverter System for X-ray Computed Tomography

NASA Astrophysics Data System (ADS)

Shibata, Junji; Kaneko, Kazuhide; Ohishi, Kiyoshi; Ando, Itaru; Ogawa, Mina; Takano, Hiroshi

This paper proposes a new output voltage control for an inverter system, which has time-delay and nonlinear load. In the next generation X-ray computed tomography of a medical device (X-ray CT) that uses the contactless power transfer method, the feedback signal often contains time-delay due to AD/DA conversion and error detection/correction time. When the PID controller of the inverter system is received the adverse effects of the time-delay, the controller often has an overshoot and a oscillated response. In order to overcome this problem, this paper proposes a compensation method based on the Smith predictor for an inverter system having a time-delay and the nonlinear loads which are the diode bridge rectifier and X-ray tube. The proposed compensation method consists of the hybrid Smith predictor system based on an equivalent analog circuit and DSP. The experimental results confirm the validity of the proposed system.

Stability of uncertain impulsive complex-variable chaotic systems with time-varying delays.

PubMed

Zheng, Song

2015-09-01

In this paper, the robust exponential stabilization of uncertain impulsive complex-variable chaotic delayed systems is considered with parameters perturbation and delayed impulses. It is assumed that the considered complex-variable chaotic systems have bounded parametric uncertainties together with the state variables on the impulses related to the time-varying delays. Based on the theories of adaptive control and impulsive control, some less conservative and easily verified stability criteria are established for a class of complex-variable chaotic delayed systems with delayed impulses. Some numerical simulations are given to validate the effectiveness of the proposed criteria of impulsive stabilization for uncertain complex-variable chaotic delayed systems. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Stability Switches, Hopf Bifurcations, and Spatio-temporal Patterns in a Delayed Neural Model with Bidirectional Coupling

NASA Astrophysics Data System (ADS)

Song, Yongli; Zhang, Tonghua; Tadé, Moses O.

2009-12-01

The dynamical behavior of a delayed neural network with bi-directional coupling is investigated by taking the delay as the bifurcating parameter. Some parameter regions are given for conditional/absolute stability and Hopf bifurcations by using the theory of functional differential equations. As the propagation time delay in the coupling varies, stability switches for the trivial solution are found. Conditions ensuring the stability and direction of the Hopf bifurcation are determined by applying the normal form theory and the center manifold theorem. We also discuss the spatio-temporal patterns of bifurcating periodic oscillations by using the symmetric bifurcation theory of delay differential equations combined with representation theory of Lie groups. In particular, we obtain that the spatio-temporal patterns of bifurcating periodic oscillations will alternate according to the change of the propagation time delay in the coupling, i.e., different ranges of delays correspond to different patterns of neural activities. Numerical simulations are given to illustrate the obtained results and show the existence of bursts in some interval of the time for large enough delay.

Minimum expected delay-based routing protocol (MEDR) for Delay Tolerant Mobile Sensor Networks.

PubMed

Feng, Yong; Liu, Ming; Wang, Xiaomin; Gong, Haigang

2010-01-01

It is a challenging work to develop efficient routing protocols for Delay Tolerant Mobile Sensor Networks (DTMSNs), which have several unique characteristics such as sensor mobility, intermittent connectivity, energy limit, and delay tolerability. In this paper, we propose a new routing protocol called Minimum Expected Delay-based Routing (MEDR) tailored for DTMSNs. MEDR achieves a good routing performance by finding and using the connected paths formed dynamically by mobile sensors. In MEDR, each sensor maintains two important parameters: Minimum Expected Delay (MED) and its expiration time. According to MED, messages will be delivered to the sensor that has at least a connected path with their hosting nodes, and has the shortest expected delay to communication directly with the sink node. Because of the changing network topology, the path is fragile and volatile, so we use the expiration time of MED to indicate the valid time of the path, and avoid wrong transmissions. Simulation results show that the proposed MEDR achieves a higher message delivery ratio with lower transmission overhead and data delivery delay than other DTMSN routing approaches.

Constructing Hopf bifurcation lines for the stability of nonlinear systems with two time delays

NASA Astrophysics Data System (ADS)

Nguimdo, Romain Modeste

2018-03-01

Although the plethora real-life systems modeled by nonlinear systems with two independent time delays, the algebraic expressions for determining the stability of their fixed points remain the Achilles' heel. Typically, the approach for studying the stability of delay systems consists in finding the bifurcation lines separating the stable and unstable parameter regions. This work deals with the parametric construction of algebraic expressions and their use for the determination of the stability boundaries of fixed points in nonlinear systems with two independent time delays. In particular, we concentrate on the cases for which the stability of the fixed points can be ascertained from a characteristic equation corresponding to that of scalar two-delay differential equations, one-component dual-delay feedback, or nonscalar differential equations with two delays for which the characteristic equation for the stability analysis can be reduced to that of a scalar case. Then, we apply our obtained algebraic expressions to identify either the parameter regions of stable microwaves generated by dual-delay optoelectronic oscillators or the regions of amplitude death in identical coupled oscillators.

Improve the Communication, Decrease the Distance: The Investigation into Problematic Communication and Delays in Inter-Hospital Transfer of Rural Trauma Patients

ERIC Educational Resources Information Center

Avtgis, Theodore A.; Polack, E. Phillips; Martin, Matthew M.; Rossi, Daniel

2010-01-01

Time delays in the treatment and transfer of trauma patients is a contributing factor responsible for many fatalities. Time delays are more characteristic of rural trauma systems due to factors such as greater distance, and delays in accident reporting. Efforts to reduce the trauma transfer process have resulted in many changes in protocol and use…

Delay-controlled primary and stochastic resonances of the SD oscillator with stiffness nonlinearities

NASA Astrophysics Data System (ADS)

Yang, Tao; Cao, Qingjie

2018-03-01

This work presents analytical studies of the stiffness nonlinearities SD (smooth and discontinuous) oscillator under displacement and velocity feedback control with a time delay. The SD oscillator can capture the qualitative characteristics of quasi-zero-stiffness and negative-stiffness. We focus mainly on the primary resonance of the quasi-zero-stiffness SD oscillator and the stochastic resonance (SR) of the negative-stiffness SD oscillator. Using the averaging method, we have been analyzed the amplitude response of the quasi-zero-stiffness SD oscillator. In this regard, the optimum time delay for changing the control intensity according to the optimization standard proposed can be obtained. For the optimum time delay, increasing the displacement feedback intensity is advantageous to suppress the vibrations in resonant regime where vibration isolation is needed, however, increasing the velocity feedback intensity is advantageous to strengthen the vibrations. Moreover, the effects of time-delayed feedback on the SR of the negative-stiffness SD oscillator are investigated under harmonic forcing and Gaussian white noise, based on the Langevin and Fokker-Planck approaches. The time-delayed feedback can enhance the SR phenomenon where vibrational energy harvesting is needed. This paper established the relationship between the parameters and vibration properties of a stiffness nonlinearities SD which provides the guidance for optimizing time-delayed control for vibration isolation and vibrational energy harvesting of the nonlinear systems.

Autonomous Mission Operations

NASA Technical Reports Server (NTRS)

Frank, Jeremy; Spirkovska, Lilijana; McCann, Rob; Wang, Lui; Pohlkamp, Kara; Morin, Lee

2012-01-01

NASA's Advanced Exploration Systems Autonomous Mission Operations (AMO) project conducted an empirical investigation of the impact of time-delay on todays mission operations, and of the effect of processes and mission support tools designed to mitigate time-delay related impacts. Mission operation scenarios were designed for NASA's Deep Space Habitat (DSH), an analog spacecraft habitat, covering a range of activities including nominal objectives, DSH system failures, and crew medical emergencies. The scenarios were simulated at time-delay values representative of Lunar (1.2-5 sec), Near Earth Object (NEO) (50 sec) and Mars (300 sec) missions. Each combination of operational scenario and time-delay was tested in a Baseline configuration, designed to reflect present-day operations of the International Space Station, and a Mitigation configuration in which a variety of software tools, information displays, and crew-ground communications protocols were employed to assist both crews and Flight Control Team (FCT) members with the long-delay conditions. Preliminary findings indicate: 1) Workload of both crew members and FCT members generally increased along with increasing time delay. 2) Advanced procedure execution viewers, caution and warning tools, and communications protocols such as text messaging decreased the workload of both flight controllers and crew, and decreased the difficulty of coordinating activities. 3) Whereas crew workload ratings increased between 50 sec and 300 sec of time-delay in the Baseline configuration, workload ratings decreased (or remained flat) in the Mitigation configuration.

A Demonstration of Precise Calibration of Tropospheric Delay Fluctuations with Water Vapor Radiometers

NASA Technical Reports Server (NTRS)

Teitelbaum, L. P.; Keihm, S. J.; Linfield, R. P.; Mahoney, M. J.; Resch, G. M.

1996-01-01

The ability of water vapor radiometers (WVRs) to calibrate changes in tropospheric delay was demonstrated during very long baseline radio interferometer (VLBI) observations at Goldstone, California. WVR measurements reduced the observed VLBI delay variations over a 13 hr period by a factor of approx. = 2.5. When applied to shorter time scales, a approx. = 50% reduction in 100-700 s delay variations was achieved during conditions of high tropospheric activity. Thermal WVR noise precluded calibration of short time scale delay fluctuations during quiet tropospheric conditions.

Maximum principle for a stochastic delayed system involving terminal state constraints.

PubMed

Wen, Jiaqiang; Shi, Yufeng

2017-01-01

We investigate a stochastic optimal control problem where the controlled system is depicted as a stochastic differential delayed equation; however, at the terminal time, the state is constrained in a convex set. We firstly introduce an equivalent backward delayed system depicted as a time-delayed backward stochastic differential equation. Then a stochastic maximum principle is obtained by virtue of Ekeland's variational principle. Finally, applications to a state constrained stochastic delayed linear-quadratic control model and a production-consumption choice problem are studied to illustrate the main obtained result.

Actual Operation Simulation of RESSOX Ground Experiments

DTIC Science & Technology

2010-11-01

Note 1289,” (Hewlett-Packard), 60 pp. [5] F. Tappero, A. Dempster, T . Iwata, M. Imae, T . Ikegami , Y. Fukuyama, K. Hagimoto, and A. Iwasaki, 2006...Delay Ionospheric Delay Ku-band Delay Estimation Frequency- Independent part Frequency- Dependent part Elapsed Time with Current Time Set as 0 (s) T ...im e t o b e A d ju s te d 0-6-105 Extrapolated with First- Order Least-Squares Filter Time Adjustment Command 42 nd Annual Precise Time and Time

Modeling the pharmacokinetics of extended release pharmaceutical systems

NASA Astrophysics Data System (ADS)

di Muria, Michela; Lamberti, Gaetano; Titomanlio, Giuseppe

2009-03-01

The pharmacokinetic (PK) models predict the hematic concentration of drugs after the administration. In compartment modeling, the body is described by a set of interconnected “vessels” or “compartments”; the modeling consisting of transient mass balances. Usually the orally administered drugs were considered as immediately available: this cannot describe the administration of extended-release systems. In this work we added to the traditional compartment models the ability to account for a delay in administration, relating this delay to in vitro data. Firstly, the method was validated, applying the model to the dosage of nicotine by chewing-gum; the model was tuned by in vitro/in vivo data of drugs (divalproex-sodium and diltiazem) with medium-rate release kinetics, then it was applied in describing in vivo evolutions due to the assumption of fast- and slow-release systems. The model reveals itself predictive, the same of a Level A in vitro/in vivo correlation, but being physically based, it is preferable to a purely statistical method.

Observer-based output feedback control of networked control systems with non-uniform sampling and time-varying delay

NASA Astrophysics Data System (ADS)

Meng, Su; Chen, Jie; Sun, Jian

2017-10-01

This paper investigates the problem of observer-based output feedback control for networked control systems with non-uniform sampling and time-varying transmission delay. The sampling intervals are assumed to vary within a given interval. The transmission delay belongs to a known interval. A discrete-time model is first established, which contains time-varying delay and norm-bounded uncertainties coming from non-uniform sampling intervals. It is then converted to an interconnection of two subsystems in which the forward channel is delay-free. The scaled small gain theorem is used to derive the stability condition for the closed-loop system. Moreover, the observer-based output feedback controller design method is proposed by utilising a modified cone complementary linearisation algorithm. Finally, numerical examples illustrate the validity and superiority of the proposed method.

Understanding Preprocedure Patient Flow in IR.

PubMed

Zafar, Abdul Mueed; Suri, Rajeev; Nguyen, Tran Khanh; Petrash, Carson Cope; Fazal, Zanira

2016-08-01

To quantify preprocedural patient flow in interventional radiology (IR) and to identify potential contributors to preprocedural delays. An administrative dataset was used to compute time intervals required for various preprocedural patient-flow processes. These time intervals were compared across on-time/delayed cases and inpatient/outpatient cases by Mann-Whitney U test. Spearman ρ was used to assess any correlation of the rank of a procedure on a given day and the procedure duration to the preprocedure time. A linear-regression model of preprocedure time was used to further explore potential contributing factors. Any identified reason(s) for delay were collated. P < .05 was considered statistically significant. Of the total 1,091 cases, 65.8% (n = 718) were delayed. Significantly more outpatient cases started late compared with inpatient cases (81.4% vs 45.0%; P < .001, χ(2) test). The multivariate linear regression model showed outpatient status, length of delay in arrival, and longer procedure times to be significantly associated with longer preprocedure times. Late arrival of patients (65.9%), unavailability of physicians (18.4%), and unavailability of procedure room (13.0%) were the three most frequently identified reasons for delay. The delay was multifactorial in 29.6% of cases (n = 213). Objective measurement of preprocedural IR patient flow demonstrated considerable waste and highlighted high-yield areas of possible improvement. A data-driven approach may aid efficient delivery of IR care. Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.

Stability and delay sensitivity of neutral fractional-delay systems.

PubMed

Xu, Qi; Shi, Min; Wang, Zaihua

2016-08-01

This paper generalizes the stability test method via integral estimation for integer-order neutral time-delay systems to neutral fractional-delay systems. The key step in stability test is the calculation of the number of unstable characteristic roots that is described by a definite integral over an interval from zero to a sufficient large upper limit. Algorithms for correctly estimating the upper limits of the integral are given in two concise ways, parameter dependent or independent. A special feature of the proposed method is that it judges the stability of fractional-delay systems simply by using rough integral estimation. Meanwhile, the paper shows that for some neutral fractional-delay systems, the stability is extremely sensitive to the change of time delays. Examples are given for demonstrating the proposed method as well as the delay sensitivity.

Unequal-Arm Interferometry and Ranging in Space

NASA Technical Reports Server (NTRS)

Tinto, Massimo

2005-01-01

Space-borne interferometric gravitational wave detectors, sensitive in the low-frequency (millihertz) band, will fly in the next decade. In these detectors the spacecraft-to-spacecraft light-traveltimes will necessarily be unequal, time-varying, and (due to aberration) have different time delays on up- and down-links. By using knowledge of the inter-spacecraft light-travel-times and their time evolution it is possible to cancel in post-processing the otherwise dominant laser phase noise and obtain a variety of interferometric data combinations sensitive to gravitational radiation. This technique, which has been named Time-Delay Interferometry (TDI), can be implemented with constellations of three or more formation-flying spacecraft that coherently track each other. As an example application we consider the Laser Interferometer Space Antenna (LISA) mission and show that TDI combinations can be synthesized by properly time-shifting and linearly combining the phase measurements performed on board the three spacecraft. Since TDI exactly suppresses the laser noises when the delays coincide with the light-travel-times, we then show that TDI can also be used for estimating the time-delays needed for its implementation. This is done by performing a post-processing non-linear minimization procedure, which provides an effective, powerful, and simple way for making measurements of the inter-spacecraft light-travel-times. This processing technique, named Time-Delay Interferometric Ranging (TDIR), is highly accurate in estimating the time-delays and allows TDI to be successfully implemented without the need of a dedicated ranging subsystem.

Depot effect of bioactive components in experimental membrane filtrations

NASA Astrophysics Data System (ADS)

Mitev, D.; Peshev, D.; Peev, G.; Peeva, L.

2017-01-01

Depot effects were found to be accompanying phenomena of membrane separation processes. Accumulation of target species in the membrane matrix during feasibility tests can hamper proper conclusions or compromise the filtration results. Therefore, we investigated the effects of delayed membrane release of chlorogenic acid and caffeine, considered as key compounds of interest in spent coffee products’ recovery treatment. Permeate fluxes and key components release were studied in course of 24 hours via nanofiltration of pure solvent, both immediately after the mock solution filtration and after idle stay. Conclusions are drawn and recommendations advised for proper analysis of experimental data on membrane screening.

Delay-induced wave instabilities in single-species reaction-diffusion systems

NASA Astrophysics Data System (ADS)

Otto, Andereas; Wang, Jian; Radons, Günter

2017-11-01

The Turing (wave) instability is only possible in reaction-diffusion systems with more than one (two) components. Motivated by the fact that a time delay increases the dimension of a system, we investigate the presence of diffusion-driven instabilities in single-species reaction-diffusion systems with delay. The stability of arbitrary one-component systems with a single discrete delay, with distributed delay, or with a variable delay is systematically analyzed. We show that a wave instability can appear from an equilibrium of single-species reaction-diffusion systems with fluctuating or distributed delay, which is not possible in similar systems with constant discrete delay or without delay. More precisely, we show by basic analytic arguments and by numerical simulations that fast asymmetric delay fluctuations or asymmetrically distributed delays can lead to wave instabilities in these systems. Examples, for the resulting traveling waves are shown for a Fisher-KPP equation with distributed delay in the reaction term. In addition, we have studied diffusion-induced instabilities from homogeneous periodic orbits in the same systems with variable delay, where the homogeneous periodic orbits are attracting resonant periodic solutions of the system without diffusion, i.e., periodic orbits of the Hutchinson equation with time-varying delay. If diffusion is introduced, standing waves can emerge whose temporal period is equal to the period of the variable delay.

Teleoperation in surgical robotics--network latency effects on surgical performance.

PubMed

Lum, Mitchell J H; Rosen, Jacob; King, Hawkeye; Friedman, Diana C W; Lendvay, Thomas S; Wright, Andrew S; Sinanan, Mika N; Hannaford, Blake

2009-01-01

A teleoperated surgical robotic system allows surgical procedures to be conducted across long distances while utilizing wired and wireless communication with a wide spectrum of performance that may affect the outcome. An open architecture portable surgical robotic system (Raven) was developed for both open and minimally invasive surgery. The system has been the subject of an intensive telesurgical experimental protocol aimed at exploring the boundaries of the system and surgeon performance during a series of field experiments in extreme environments (desert and underwater) teleportation between US, Europe, and Japan as well as lab experiments under synthetic fixed time delay. One standard task (block transfer emulating tissue manipulation) of the Fundamentals of Laparoscopic Surgery (FLS) training kit was used for the experimental protocol. Network characterization indicated a typical time delay in the range of 16-172 ms in field experiments. The results of the lab experiments showed that the completion time of the task as well as the length of the tool tip trajectory significantly increased (alpha< 0.02) as time delay increased in the range of 0-0.5 sec increased. For teleoperation with a time delay of 0.25s and 0.5s the task completion time was lengthened by a factor of 1.45 and 2.04 with respect to no time delay, whereas the length of the tools' trajectory was increased by a factor of 1.28 and 1.53 with respect to no time delay. There were no statistical differences between experienced surgeons and non-surgeons in the number of errors (block drooping) as well as the completion time and the tool tip path length at different time delays.

Correction of ultrasonic wave aberration with a time delay and amplitude filter.

PubMed

Måsøy, Svein-Erik; Johansen, Tonni F; Angelsen, Bjørn

2003-04-01

Two-dimensional simulations with propagation through two different heterogeneous human body wall models have been performed to analyze different correction filters for ultrasonic wave aberration due to forward wave propagation. The different models each produce most of the characteristic aberration effects such as phase aberration, relatively strong amplitude aberration, and waveform deformation. Simulations of wave propagation from a point source in the focus (60 mm) of a 20 mm transducer through the body wall models were performed. Center frequency of the pulse was 2.5 MHz. Corrections of the aberrations introduced by the two body wall models were evaluated with reference to the corrections obtained with the optimal filter: a generalized frequency-dependent phase and amplitude correction filter [Angelsen, Ultrasonic Imaging (Emantec, Norway, 2000), Vol. II]. Two correction filters were applied, a time delay filter, and a time delay and amplitude filter. Results showed that correction with a time delay filter produced substantial reduction of the aberration in both cases. A time delay and amplitude correction filter performed even better in both cases, and gave correction close to the ideal situation (no aberration). The results also indicated that the effect of the correction was very sensitive to the accuracy of the arrival time fluctuations estimate, i.e., the time delay correction filter.

Delayed and Unreported Drug-Susceptibility Testing Results in the US National Tuberculosis Surveillance System, 1993-2014.

PubMed

Jones, Jefferson Michael; Armstrong, Lori R

Drug-susceptibility testing (DST) of Mycobacterium tuberculosis is necessary for identifying drug-resistant tuberculosis, administering effective treatment regimens, and preventing the spread of drug-resistant tuberculosis. DST is recommended for all culture-confirmed cases of tuberculosis. We examined trends in delayed and unreported DST results in the Centers for Disease Control and Prevention's National Tuberculosis Surveillance System. We analyzed culture-confirmed tuberculosis cases reported to the National Tuberculosis Surveillance System during 1993-2014 for annual trends in initial DST reporting for first-line antituberculosis drugs and trends in on-time, delayed, and unreported results. We defined on-time reporting as DST results received during the same calendar year in which the patient's case was reported or ≤4 months after the calendar year ended and delayed reporting as DST results received after the calendar year. We compared cases with on-time, delayed, and unreported DST results by patient and tuberculosis program characteristics. The proportion of cases with reported results for all first-line antituberculosis drugs increased during 1993-2011. Reporting of pyrazinamide results was lower than reporting of other drugs. However, during 2000-2012, of 134 787 tuberculosis cases reported to the National Tuberculosis Surveillance System, reporting was on time for 125 855 (93.4%) cases, delayed for 5332 (4.0%) cases, and unreported for 3600 (2.7%) cases. Despite increases in the proportion of cases with on-time DST results, delayed and unreported results persisted. Carefully assessing causes for delayed and unreported DST results should lead to more timely reporting of drug-resistant tuberculosis.

Cortical Composition Hierarchy Driven by Spine Proportion Economical Maximization or Wire Volume Minimization

PubMed Central

Karbowski, Jan

2015-01-01

The structure and quantitative composition of the cerebral cortex are interrelated with its computational capacity. Empirical data analyzed here indicate a certain hierarchy in local cortical composition. Specifically, neural wire, i.e., axons and dendrites take each about 1/3 of cortical space, spines and glia/astrocytes occupy each about (1/3)2, and capillaries around (1/3)4. Moreover, data analysis across species reveals that these fractions are roughly brain size independent, which suggests that they could be in some sense optimal and thus important for brain function. Is there any principle that sets them in this invariant way? This study first builds a model of local circuit in which neural wire, spines, astrocytes, and capillaries are mutually coupled elements and are treated within a single mathematical framework. Next, various forms of wire minimization rule (wire length, surface area, volume, or conduction delays) are analyzed, of which, only minimization of wire volume provides realistic results that are very close to the empirical cortical fractions. As an alternative, a new principle called “spine economy maximization” is proposed and investigated, which is associated with maximization of spine proportion in the cortex per spine size that yields equally good but more robust results. Additionally, a combination of wire cost and spine economy notions is considered as a meta-principle, and it is found that this proposition gives only marginally better results than either pure wire volume minimization or pure spine economy maximization, but only if spine economy component dominates. However, such a combined meta-principle yields much better results than the constraints related solely to minimization of wire length, wire surface area, and conduction delays. Interestingly, the type of spine size distribution also plays a role, and better agreement with the data is achieved for distributions with long tails. In sum, these results suggest that for the efficiency of local circuits wire volume may be more primary variable than wire length or temporal delays, and moreover, the new spine economy principle may be important for brain evolutionary design in a broader context. PMID:26436731

Time delay in Swiss cheese gravitational lensing

NASA Astrophysics Data System (ADS)

Chen, B.; Kantowski, R.; Dai, X.

2010-08-01

We compute time delays for gravitational lensing in a flat Λ dominated cold dark matter Swiss cheese universe. We assume a primary and secondary pair of light rays are deflected by a single point mass condensation described by a Kottler metric (Schwarzschild with Λ) embedded in an otherwise homogeneous cosmology. We find that the cosmological constant’s effect on the difference in arrival times is nonlinear and at most around 0.002% for a large cluster lens; however, we find differences from time delays predicted by conventional linear lensing theory that can reach ˜4% for these large lenses. The differences in predicted delay times are due to the failure of conventional lensing to incorporate the lensing mass into the mean mass density of the universe.

H∞ control problem of linear periodic piecewise time-delay systems

NASA Astrophysics Data System (ADS)

Xie, Xiaochen; Lam, James; Li, Panshuo

2018-04-01

This paper investigates the H∞ control problem based on exponential stability and weighted L2-gain analyses for a class of continuous-time linear periodic piecewise systems with time delay. A periodic piecewise Lyapunov-Krasovskii functional is developed by integrating a discontinuous time-varying matrix function with two global terms. By applying the improved constraints to the stability and L2-gain analyses, sufficient delay-dependent exponential stability and weighted L2-gain criteria are proposed for the periodic piecewise time-delay system. Based on these analyses, an H∞ control scheme is designed under the considerations of periodic state feedback control input and iterative optimisation. Finally, numerical examples are presented to illustrate the effectiveness of our proposed conditions.

Study on statistical breakdown delay time in argon gas using a W-band millimeter-wave gyrotron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Dongsung; Yu, Dongho; Choe, MunSeok

2016-04-15

In this study, we investigated plasma initiation delay times for argon volume breakdown at the W-band frequency regime. The threshold electric field is defined as the minimum electric field amplitude needed for plasma breakdown at various pressures. The measured statistical delay time showed an excellent agreement with the theoretical Gaussian distribution and the theoretically estimated formative delay time. Also, we demonstrated that the normalized effective electric field as a function of the product of pressure and formative time shows an outstanding agreement to that of 1D particle-in-cell simulation coupled with a Monte Carlo collision model [H. C. Kim and J.more » P. Verboncoeur, Phys. Plasmas 13, 123506 (2006)].« less

Impact of health care system delay in patients with ST-elevation myocardial infarction on return to labor market and work retirement.

PubMed

Laut, Kristina Grønborg; Hjort, Jacob; Engstrøm, Thomas; Jensen, Lisette Okkels; Tilsted Hansen, Hans-Henrik; Jensen, Jan Skov; Pedersen, Frants; Jørgensen, Erik; Holmvang, Lene; Pedersen, Alma Becic; Christensen, Erika Frischknecht; Lippert, Freddy; Lang-Jensen, Torsten; Jans, Henning; Hansen, Poul Anders; Trautner, Sven; Kristensen, Steen Dalby; Lassen, Jens Flensted; Lash, Timothy L; Clemmensen, Peter; Terkelsen, Christian Juhl

2014-12-15

System delay (delay from emergency medical service call to reperfusion with primary percutaneous coronary intervention [PPCI]) is acknowledged as a performance measure in ST-elevation myocardial infarction (STEMI), as shorter system delay is associated with lower mortality. It is unknown whether system delay also impacts ability to stay in the labor market. Therefore, the aim of the study was to evaluate whether system delay is associated with duration of absence from work or time to retirement from work among patients with STEMI treated with PPCI. We conducted a population-based cohort study including patients ≤67 years of age who were admitted with STEMI from January 1, 1999, to December 1, 2011 and treated with PPCI. Data were derived from Danish population-based registries. Only patients who were full- or part-time employed before their STEMI admission were included. Association between system delay and time to return to the labor market was analyzed using a competing-risk regression analysis. Association between system delay and time to retirement from work was analyzed using a Cox regression model. A total of 4,061 patients were included. Ninety-three percent returned to the labor market during 4 years of follow-up, and 41% retired during 8 years of follow-up. After adjustment, system delay >120 minutes was associated with reduced resumption of work (subhazard ratio 0.86, 95% confidence interval 0.81 to 0.92) and earlier retirement from work (hazard ratio 1.21, 95% confidence interval 1.08 to 1.36). In conclusion, system delay was associated with reduced work resumption and earlier retirement. This highlights the value of system delay as a performance measure in treating patients with STEMI. Copyright © 2014 Elsevier Inc. All rights reserved.

Forward masking of dynamic acoustic intensity: effects of intensity region and end-level.

PubMed

Olsen, Kirk N; Stevens, Catherine J

2012-01-01

Overestimation of loudness change typically occurs in response to up-ramp auditory stimuli (increasing intensity) relative to down-ramps (decreasing intensity) matched on frequency, duration, and end-level. In the experiment reported, forward masking is used to investigate a sensory component of up-ramp overestimation: persistence of excitation after stimulus presentation. White-noise and synthetic vowel 3.6 s up-ramp and down-ramp maskers were presented over two regions of intensity change (40-60 dB SPL, 60-80 dB SPL). Three participants detected 10 ms 1.5 kHz pure tone signals presented at masker-offset to signal-offset delays of 10, 20, 30, 50, 90, 170 ms. Masking magnitude was significantly greater in response to up-ramps compared with down-ramps for masker-signal delays up to and including 50 ms. When controlling for an end-level recency bias (40-60 dB SPL up-ramp vs 80-60 dB SPL down-ramp), the difference in masking magnitude between up-ramps and down-ramps was not significant at each masker-signal delay. Greater sensory persistence in response to up-ramps is argued to have minimal effect on perceptual overestimation of loudness change when response biases are controlled. An explanation based on sensory adaptation is discussed.

Delay-time distribution in the scattering of time-narrow wave packets (II)—quantum graphs

NASA Astrophysics Data System (ADS)

Smilansky, Uzy; Schanz, Holger

2018-02-01

We apply the framework developed in the preceding paper in this series (Smilansky 2017 J. Phys. A: Math. Theor. 50 215301) to compute the time-delay distribution in the scattering of ultra short radio frequency pulses on complex networks of transmission lines which are modeled by metric (quantum) graphs. We consider wave packets which are centered at high wave number and comprise many energy levels. In the limit of pulses of very short duration we compute upper and lower bounds to the actual time-delay distribution of the radiation emerging from the network using a simplified problem where time is replaced by the discrete count of vertex-scattering events. The classical limit of the time-delay distribution is also discussed and we show that for finite networks it decays exponentially, with a decay constant which depends on the graph connectivity and the distribution of its edge lengths. We illustrate and apply our theory to a simple model graph where an algebraic decay of the quantum time-delay distribution is established.

Using time-delayed mutual information to discover and interpret temporal correlation structure in complex populations

NASA Astrophysics Data System (ADS)

Albers, D. J.; Hripcsak, George

2012-03-01

This paper addresses how to calculate and interpret the time-delayed mutual information (TDMI) for a complex, diversely and sparsely measured, possibly non-stationary population of time-series of unknown composition and origin. The primary vehicle used for this analysis is a comparison between the time-delayed mutual information averaged over the population and the time-delayed mutual information of an aggregated population (here, aggregation implies the population is conjoined before any statistical estimates are implemented). Through the use of information theoretic tools, a sequence of practically implementable calculations are detailed that allow for the average and aggregate time-delayed mutual information to be interpreted. Moreover, these calculations can also be used to understand the degree of homo or heterogeneity present in the population. To demonstrate that the proposed methods can be used in nearly any situation, the methods are applied and demonstrated on the time series of glucose measurements from two different subpopulations of individuals from the Columbia University Medical Center electronic health record repository, revealing a picture of the composition of the population as well as physiological features.

Comparing Teacher-Directed and Computer-Assisted Constant Time Delay for Teaching Functional Sight Words to Students with Moderate Intellectual Disability

ERIC Educational Resources Information Center

Coleman, Mari Beth; Hurley, Kevin J.; Cihak, David F.

2012-01-01

The purpose of this study was to compare the effectiveness and efficiency of teacher-directed and computer-assisted constant time delay strategies for teaching three students with moderate intellectual disability to read functional sight words. Target words were those found in recipes and were taught via teacher-delivered constant time delay or…

Distributed Optimal Consensus Control for Multiagent Systems With Input Delay.

PubMed

Zhang, Huaipin; Yue, Dong; Zhao, Wei; Hu, Songlin; Dou, Chunxia; Huaipin Zhang; Dong Yue; Wei Zhao; Songlin Hu; Chunxia Dou; Hu, Songlin; Zhang, Huaipin; Dou, Chunxia; Yue, Dong; Zhao, Wei

2018-06-01

This paper addresses the problem of distributed optimal consensus control for a continuous-time heterogeneous linear multiagent system subject to time varying input delays. First, by discretization and model transformation, the continuous-time input-delayed system is converted into a discrete-time delay-free system. Two delicate performance index functions are defined for these two systems. It is shown that the performance index functions are equivalent and the optimal consensus control problem of the input-delayed system can be cast into that of the delay-free system. Second, by virtue of the Hamilton-Jacobi-Bellman (HJB) equations, an optimal control policy for each agent is designed based on the delay-free system and a novel value iteration algorithm is proposed to learn the solutions to the HJB equations online. The proposed adaptive dynamic programming algorithm is implemented on the basis of a critic-action neural network (NN) structure. Third, it is proved that local consensus errors of the two systems and weight estimation errors of the critic-action NNs are uniformly ultimately bounded while the approximated control policies converge to their target values. Finally, two simulation examples are presented to illustrate the effectiveness of the developed method.

Factors associated with delay in trauma team activation and impact on patient outcomes.

PubMed

Connolly, Rory; Woo, Michael Y; Lampron, Jacinthe; Perry, Jeffrey J

2017-09-05

Trauma code activation is initiated by emergency physicians using physiological and anatomical criteria, mechanism of injury, and patient demographic factors. Our objective was to identify factors associated with delayed trauma team activation. We assessed consecutive cases from a regional trauma database from January 2008 to March 2014. We defined a delay in trauma code activation as a time greater than 30 minutes from the time of arrival. We conducted univariate analysis for factors potentially influencing trauma team activation, and we subsequently used multiple logistic regression analysis models for delayed activation in relation to mortality, length of stay, and time to operative management. Patients totalling 846 were included for our analysis; 4.1% (35/846) of trauma codes were activated after 30 minutes. Mean age was 40.8 years in the early group versus 49.2 in the delayed group (p=0.01). Patients were over age 70 years in 7.6% in the early activation group versus 17.1% in the delayed group (p=0.04). There was no significant difference in sex, type of injury, injury severity, or time from injury between the two groups. There was no significant difference in mortality, median length of stay, or median time to operative management. Delayed activation is linked with increasing age with no clear link to increased mortality. Given the severe injuries in the delayed cohort that required activation of the trauma team, further emphasis on the older trauma patient and interventions to recognize this vulnerable population should be made.

Hindrance of conservation biology by delays in the submission of manuscripts.

PubMed

O'Donnell, Ryan P; Supp, Sarah R; Cobbold, Stephanie M

2010-04-01

Timely dissemination of scientific findings depends not only on rapid publication of submitted manuscripts, a topic which has received much discussion, but also on rapid submission of research after the research is completed. We measured submission delay (time from the last date of data collection to the submission of a manuscript) for every paper from 14 journals in 2007 and compared these submission delays among four fields of biology (conservation, taxonomy, behavior, and evolution). Manuscripts published in leading journals in the field of conservation biology have the longest delays in publication of accepted manuscripts and the longest intervals between completion of research and submission of the manuscript. Delay in manuscript submission accounts for more than half of the total time from last date of data collection to publication. Across fields, the number of authors was significantly negatively correlated with submission delay, but conservation journals had the second highest number of authors and the greatest submission delay, so submission of conservation manuscripts was not hindered by a shortage of collaboration relative to other fields. Rejection rates were greater in conservation journals than in behavior and evolution, but rejection times were faster; thus, there were no obvious net differences among fields in the time papers spent waiting to be rejected. Publication delay has been reduced significantly in the last 7 years, but was still greater in conservation journals than in any of the other three fields we studied. Thus, the urgent field of conservation biology is hindered in both preparation and publication of manuscripts.

Direct measurement of group delay with joint time-frequency analysis of a white-light spectral interferogram.

PubMed

Deng, Yuqiang; Yang, Weijian; Zhou, Chun; Wang, Xi; Tao, Jun; Kong, Weipeng; Zhang, Zhigang

2008-12-01

We propose and demonstrate an analysis method to directly extract the group delay rather than the phase from the white-light spectral interferogram. By the joint time-frequency analysis technique, group delay is directly read from the ridge of wavelet transform, and group-delay dispersion is easily obtained by additional differentiation. The technique shows reasonable potential for the characterization of ultra-broadband chirped mirrors.

Digital tanlock loop architecture with no delay

NASA Astrophysics Data System (ADS)

Al-Kharji AL-Ali, Omar; Anani, Nader; Al-Araji, Saleh; Al-Qutayri, Mahmoud; Ponnapalli, Prasad

2012-02-01

This article proposes a new architecture for a digital tanlock loop which eliminates the time-delay block. The ? (rad) phase shift relationship between the two channels, which is generated by the delay block in the conventional time-delay digital tanlock loop (TDTL), is preserved using two quadrature sampling signals for the loop channels. The proposed system outperformed the original TDTL architecture, when both systems were tested with frequency shift keying input signal. The new system demonstrated better linearity and acquisition speed as well as improved noise performance compared with the original TDTL architecture. Furthermore, the removal of the time-delay block enables all processing to be digitally performed, which reduces the implementation complexity. Both the original TDTL and the new architecture without the delay block were modelled and simulated using MATLAB/Simulink. Implementation issues, including complexity and relation to simulation of both architectures, are also addressed.

Relation between delayed feedback and delay-coupled systems and its application to chaotic lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soriano, Miguel C., E-mail: miguel@ifisc.uib-csic.es; Flunkert, Valentin; Fischer, Ingo

2013-12-15

We present a systematic approach to identify the similarities and differences between a chaotic system with delayed feedback and two mutually delay-coupled systems. We consider the general case in which the coupled systems are either unsynchronized or in a generally synchronized state, in contrast to the mostly studied case of identical synchronization. We construct a new time-series for each of the two coupling schemes, respectively, and present analytic evidence and numerical confirmation that these two constructed time-series are statistically equivalent. From the construction, it then follows that the distribution of time-series segments that are small compared to the overall delaymore » in the system is independent of the value of the delay and of the coupling scheme. By focusing on numerical simulations of delay-coupled chaotic lasers, we present a practical example of our findings.« less

Reducing the Handover Delay in FMIPv6 Using Proactive Care-of Address Scheme

NASA Astrophysics Data System (ADS)

Li, Yong; Jin, Depeng; Su, Li; Zeng, Lieguang

To deal with the increasing number of mobile devices accessing the Internet and the increasing demands of mobility management, IETF has proposed Mobile IPv6 and its fast handover protocol FMIPv6. In FMIPv6, the possibility of Care-of Address (CoA) collision and the time for Return Routability (RR) procedure result in long handover delay, which makes it unsuitable for real-time applications. In this paper, we propose an improved handover scheme for FMIPv6, which reduces the handover delay by using proactive CoA acquisition, configuration and test method. In our proposal, collision-free CoA is proactively prepared, and the time for RR procedure does not contribute to the handover delay. Furthermore, we analyze our proposal's benefits and overhead tradeoff. The numerical results demonstrate that it outperforms the current schemes, such as FMIPv6 and enhanced FMIPv6, on the aspect of handover delay and packet transmission delay.

Automatic transponder. [measurement of the internal delay time of a transponder

NASA Technical Reports Server (NTRS)

Anderson, R. E.; Brisken, A. F.; Lewis, J. R. (Inventor)

1977-01-01

A method and apparatus for the automatic, remote measurement of the internal delay time of a transponder at the time of operation is provided. A small portion of the transmitted signal of the transponder is converted to the receive signal frequency of the transponder and supplied to the input of the transponder. The elapsed time between the receive signal locally generated and the receive signal causing the transmission of the transmitted signal is measured, said time being representative of or equal to the internal delay time of the transponder at the time of operation.

CORRECTING FOR INTERSTELLAR SCATTERING DELAY IN HIGH-PRECISION PULSAR TIMING: SIMULATION RESULTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palliyaguru, Nipuni; McLaughlin, Maura; Stinebring, Daniel

2015-12-20

Light travel time changes due to gravitational waves (GWs) may be detected within the next decade through precision timing of millisecond pulsars. Removal of frequency-dependent interstellar medium (ISM) delays due to dispersion and scattering is a key issue in the detection process. Current timing algorithms routinely correct pulse times of arrival (TOAs) for time-variable delays due to cold plasma dispersion. However, none of the major pulsar timing groups correct for delays due to scattering from multi-path propagation in the ISM. Scattering introduces a frequency-dependent phase change in the signal that results in pulse broadening and arrival time delays. Any methodmore » to correct the TOA for interstellar propagation effects must be based on multi-frequency measurements that can effectively separate dispersion and scattering delay terms from frequency-independent perturbations such as those due to a GW. Cyclic spectroscopy, first described in an astronomical context by Demorest (2011), is a potentially powerful tool to assist in this multi-frequency decomposition. As a step toward a more comprehensive ISM propagation delay correction, we demonstrate through a simulation that we can accurately recover impulse response functions (IRFs), such as those that would be introduced by multi-path scattering, with a realistic signal-to-noise ratio (S/N). We demonstrate that timing precision is improved when scatter-corrected TOAs are used, under the assumptions of a high S/N and highly scattered signal. We also show that the effect of pulse-to-pulse “jitter” is not a serious problem for IRF reconstruction, at least for jitter levels comparable to those observed in several bright pulsars.« less

Flip-flop resolving time test circuit

NASA Technical Reports Server (NTRS)

Rosenberger, F.; Chaney, T. J.

1982-01-01

Integrated circuit (IC) flip-flop resolving time parameters are measured by wafer probing, without need of dicing or bonding, throught the incorporation of test structures on an IC together with the flip-flop to be measured. Several delays that are fabricated as part of the test circuit, including a voltage-controlled delay with a resolution of a few picosecs, are calibrated as part of the test procedure by integrating them into, and out of, the delay path of a ring oscillator. Each of the delay values is calculated by subtracting the period of the ring oscillator with the delay omitted from the period with the delay included. The delay measurement technique is sufficiently general for other applications. The technique is illustrated for the case of the flip-flop parameters of a 5-micron feature size NMOS circuit.

Time-resolved coherent Raman spectroscopy by high-speed pump-probe delay scanning.

PubMed

Domingue, S R; Winters, D G; Bartels, R A

2014-07-15

Using a spinning window pump-probe delay scanner, we demonstrate a means of acquiring time-resolved vibrational spectra at rates up to 700 Hz. The time-dependent phase shift accumulated by the probe pulse in the presence of a coherently vibrating sample gives rise to a Raman-induced frequency shifting readily detectable in a balanced detector. This rapid delay scanning system represents a 23-fold increase in averaging speed and is >10× faster than state-of-the-art voice coil delay lines. These advancements make pump-probe spectroscopy a more practical means of imaging complex media.

Association between delayed bedtime and sleep-related problems among community-dwelling 2-year-old children in Japan.

PubMed

Kitamura, Shingo; Enomoto, Minori; Kamei, Yuichi; Inada, Naoko; Moriwaki, Aiko; Kamio, Yoko; Mishima, Kazuo

2015-03-13

Although delayed sleep timing causes many socio-psycho-biological problems such as sleep loss, excessive daytime sleepiness, obesity, and impaired daytime neurocognitive performance in adults, there are insufficient data showing the clinical significance of a 'night owl lifestyle' in early life. This study examined the association between habitual delayed bedtime and sleep-related problems among community-dwelling 2-year-old children in Japan. Parents/caregivers of 708 community-dwelling 2-year-old children in Nishitokyo City, Tokyo, participated in the study. The participants answered a questionnaire to evaluate their child's sleep habits and sleep-related problems for the past 1 month. Of the 425 children for whom complete data were collected, 90 (21.2%) went to bed at 22:00 or later. Children with delayed bedtime showed significantly more irregular bedtime, delayed wake time, shorter total sleep time, and difficulty in initiating and terminating sleep. Although this relationship indicated the presence of sleep debt in children with delayed bedtime, sleep onset latency did not differ between children with earlier bedtime and those with delayed bedtime. Rather, delayed bedtime was significantly associated with bedtime resistance and problems in the morning even when adjusting for nighttime and daytime sleep time. Even in 2-year-old children, delayed bedtime was associated with various sleep-related problems. The causal factors may include diminished homeostatic sleep drive due to prolonged daytime nap as well as diurnal preference (morning or night type) regulated by the biological clock.

Comparative study of phase transition and textural changes upon calcination of two commercial titania samples: A pure anatase and a mixed anatase-rutile

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kordouli, Eleana; Dracopoulos, Vassileios; Vaimakis, Tiverios

2015-12-15

The effect of calcination temperature and time on structural and textural changes of two commercial TiO{sub 2} samples (pure anatase and a mixture of anatase and rutile) has been investigated using N{sub 2} physisorption, ex-situ and in-situ X-ray powder diffraction, differential scanning calorimetry and UV–vis diffuse reflectance spectroscopy. The increase of the calcination temperature (up to 700 °C) and time (up to 8 h) causes only textural changes in the pure anatase, whereas a transformation of the anatase to rutile takes place, in addition, in the mixed titania (containing anatase and rutile). The textural changes observed in pure anatase samplemore » were attributed to solid state diffusion leading to an increase in the size of anatase nanocrystals, through sintering. Thus, the mean pore diameter shifts to higher values and the pore volume and specific surface area decrease. The successful application of the Johnson–Mehl–Avrami–Kolmogorov model in the kinetic data concerning the pure anatase indicates a mass transfer control of sintering process. Similar textural changes were also observed upon calcination of the sample containing anatase and rutile. In this case not only sintering but the anatase to rutile transformation contributes also to the textural changes. Kinetic analysis showed that the rutile nanocrystals in the mixed titania served as seed for by-passing the high energy barrier nucleation step allowing/facilitating thus the anatase to rutile transformation. A fine control of the anatase to rutile ratio and thus of energy-gap and the population of hetero-junctions may be obtained by adjusting the calcination temperature and time. - Graphical Abstract: Dependence of anatase content of P25 on the calcination temperature (600 °C (■), 650 °C (●), 700 °C (▲)) and time. - Highlights: • Increase of calcination temperature up to 800 °C and time up to 8 h causes only textural changes in pure anatase • Progressive transformation of anatase to rutile with time takes place in the mixed titania above 600 °C • A high activation energy barrier inhibits the solid state transformation in pure anatase • Rutile nanocrystals in mixed titania serve as seeding for favouring transformation • Calcination temperature and time allow a fine control of E{sub g} and heterojunctions population in mixed titania.« less

The nature of adolescent competencies predicted by preschool delay of gratification.

PubMed

Mischel, W; Shoda, Y; Peake, P K

1988-04-01

Delay of gratification, assessed in a series of experiments when the subjects were in preschool, was related to parental personality ratings obtained a decade later for 95 of these children in adolescence. Clear and consistent patterns of correlations between self-imposed delay time in preschool and later ratings were found for both sexes over this time span. Delay behavior predicted a set of cognitive and social competencies and stress tolerance consistent with experimental analyses of the process underlying effective delay in the preschool delay situation. Specifically, children who were able to wait longer at age 4 or 5 became adolescents whose parents rated them as more academically and socially competent, verbally fluent, rational, attentive, planful, and able to deal well with frustration and stress. Comparisons with related longitudinal research using other delay situations help to clarify the important features of the situations and person variables involved in different aspects of delay of gratification.

Improved extraction of avocado oil by application of sono-physical processes.

PubMed

Martínez-Padilla, Laura Patricia; Franke, Lisa; Xu, Xin-Qing; Juliano, Pablo

2018-01-01

Ultrasound treatment is known to increase the oil extractability in olive and palm oil processes. This work examined the effect of ultrasound conditioning of avocado puree on oil extractability and quality, at low (18+40kHz) and high (2MHz) frequencies, at litre-scale. Other ultrasound parameters evaluated included high frequency effect (0.4, 0.6, and 2MHz; 5min; 90kJ/kg) and sonication time (2.5-10min at 2MHz), without malaxation. Finally, a megasonic post-malaxation intervention was assessed at selected malaxation times (15, 30, and 60min). Both low and high frequency ultrasound treatments of the non-malaxed avocado puree improved extractability by 15-24% additional oil recovery, with the highest extractability achieved after 2MHz treatments, depending on the fruit maturity and oil content. There was no preferential improvement on oil extractability observed across high frequencies, even though extractability increased with sonication time. Ultrasound treatment also showed a positive effect after puree malaxation. Oils obtained from sonicated purees showed peroxide and free fatty acid values below the industrial specification levels and an increase in total phenolic compounds after 2MHz treatment. High frequency ultrasound conditioning of avocado puree can enhance oil separation and potentially decrease the malaxation time in industrial processes without impacting on oil quality. Copyright © 2017 Elsevier B.V. All rights reserved.

Development and blood compatibility assessment of electrospun polyvinyl alcohol blended with metallocene polyethylene and plectranthus amboinicus (PVA/mPE/PA) for bone tissue engineering.

PubMed

Qi, Jie; Zhang, Huang; Wang, Yingzhou; Mani, Mohan Prasath; Jaganathan, Saravana Kumar

2018-01-01

Currently, the design of extracellular matrix (ECM) with nanoscale properties in bone tissue engineering is challenging. For bone tissue engineering, the ECM must have certain properties such as being nontoxic, highly porous, and should not cause foreign body reactions. In this study, the hybrid scaffold based on polyvinyl alcohol (PVA) blended with metallocene polyethylene (mPE) and plectranthus amboinicus (PA) was fabricated for bone tissue engineering via electrospinning. The fabricated hybrid nanocomposites were characterized by scanning electron microscopy (SEM), Fourier transform and infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), contact angle measurement, and atomic force microscopy (AFM). Furthermore, activated partial thromboplastin time (APTT), prothrombin time (PT), and hemolytic assays were used to investigate the blood compatibility of the prepared hybrid nanocomposites. The prepared hybrid nanocomposites showed reduced fiber diameter (238±45 nm) and also increased porosity (87%) with decreased pore diameter (340±86 nm) compared with pure PVA. The interactions between PVA, mPE, and PA were identified by the formation of the additional peaks as revealed in FTIR. Furthermore, the prepared hybrid nanocomposites showed a decreased contact angle of 51°±1.32° indicating a hydrophilic nature and exhibited lower thermal stability compared to pristine PVA. Moreover, the mechanical results revealed that the electrospun scaffold showed an improved tensile strength of 3.55±0.29 MPa compared with the pristine PVA (1.8±0.52 MPa). The prepared hybrid nanocomposites showed delayed blood clotting as noted in APTT and PT assays indicating better blood compatibility. Moreover, the hemolysis assay revealed that the hybrid nanocomposites exhibited a low hemolytic index of 0.6% compared with pure PVA, which was 1.6% suggesting the safety of the developed nanocomposite to red blood cells (RBCs). The prepared nanocomposites exhibited better physico-chemical properties, sufficient porosity, mechanical strength, and blood compatibility, which favors it as a valuable candidate in bone tissue engineering for repairing the bone defects.

Apparatus for and method of monitoring for breached fuel elements

DOEpatents

Gross, K.C.; Strain, R.V.

1981-04-28

This invention teaches improved apparatus for the method of detecting a breach in cladded fuel used in a nuclear reactor. The detector apparatus uses a separate bypass loop for conveying part of the reactor coolant away from the core, and at least three separate delayed-neutron detectors mounted proximate this detector loop. The detectors are spaced apart so that the coolant flow time from the core to each detector is different, and these differences are known. The delayed-neutron activity at the detectors is a function of the delay time after the reaction in the fuel until the coolant carrying the delayed-neutron emitter passes the respective detector. This time delay is broken down into separate components including an isotopic holdup time required for the emitter to move through the fuel from the reaction to the coolant at the breach, and two transit times required for the emitter now in the coolant to flow from the breach to the detector loop and then via the loop to the detector.

The synchronization of asymmetric-structured electric coupling neuronal system

NASA Astrophysics Data System (ADS)

Wang, Guanping; Jin, Wuyin; Liu, Hao; Sun, Wei

2018-02-01

Based on the Hindmarsh-Rose (HR) model, the synchronization dynamics of asymmetric-structured electric coupling two neuronal system is investigated in this paper. It is discovered that when the time-delay scope and coupling strength for the synchronization are correlated positively under unequal time delay, the time-delay difference does not make a clear distinction between the two individual inter-spike intervals (ISI) bifurcation diagrams of the two coupled neurons. Therefore, the superficial difference of the system synchronization dynamics is not obvious for the unequal time-delay feedback. In the asymmetrical current incentives under asymmetric electric coupled system, the two neurons can only be almost completely synchronized in specific area of the interval which end-pointed with two discharge modes for a single neuron under different stimuli currents before coupling, but the intervention of time-delay feedback, together with the change of the coupling strength, can make the coupled system not only almost completely synchronized within anywhere in the front area, but also outside of it.

Multiple-parameter bifurcation analysis in a Kuramoto model with time delay and distributed shear

NASA Astrophysics Data System (ADS)

Niu, Ben; Zhang, Jiaming; Wei, Junjie

2018-05-01

In this paper, time delay effect and distributed shear are considered in the Kuramoto model. On the Ott-Antonsen's manifold, through analyzing the associated characteristic equation of the reduced functional differential equation, the stability boundary of the incoherent state is derived in multiple-parameter space. Moreover, very rich dynamical behavior such as stability switches inducing synchronization switches can occur in this equation. With the loss of stability, Hopf bifurcating coherent states arise, and the criticality of Hopf bifurcations is determined by applying the normal form theory and the center manifold theorem. On one hand, theoretical analysis indicates that the width of shear distribution and time delay can both eliminate the synchronization then lead the Kuramoto model to incoherence. On the other, time delay can induce several coexisting coherent states. Finally, some numerical simulations are given to support the obtained results where several bifurcation diagrams are drawn, and the effect of time delay and shear is discussed.

Impulsive stabilization and impulsive synchronization of discrete-time delayed neural networks.

PubMed

Chen, Wu-Hua; Lu, Xiaomei; Zheng, Wei Xing

2015-04-01

This paper investigates the problems of impulsive stabilization and impulsive synchronization of discrete-time delayed neural networks (DDNNs). Two types of DDNNs with stabilizing impulses are studied. By introducing the time-varying Lyapunov functional to capture the dynamical characteristics of discrete-time impulsive delayed neural networks (DIDNNs) and by using a convex combination technique, new exponential stability criteria are derived in terms of linear matrix inequalities. The stability criteria for DIDNNs are independent of the size of time delay but rely on the lengths of impulsive intervals. With the newly obtained stability results, sufficient conditions on the existence of linear-state feedback impulsive controllers are derived. Moreover, a novel impulsive synchronization scheme for two identical DDNNs is proposed. The novel impulsive synchronization scheme allows synchronizing two identical DDNNs with unknown delays. Simulation results are given to validate the effectiveness of the proposed criteria of impulsive stabilization and impulsive synchronization of DDNNs. Finally, an application of the obtained impulsive synchronization result for two identical chaotic DDNNs to a secure communication scheme is presented.

Slow-light, band-edge waveguides for tunable time delays.

PubMed

Povinelli, M; Johnson, Steven; Joannopoulos, J

2005-09-05

We propose the use of slow-light, band-edge waveguides for compact, integrated, tunable optical time delays. We show that slow group velocities at the photonic band edge give rise to large changes in time delay for small changes in refractive index, thereby shrinking device size. Figures of merit are introduced to quantify the sensitivity, as well as the accompanying signal degradation due to dispersion. It is shown that exact calculations of the figures of merit for a realistic, three-dimensional grating structure are well predicted by a simple quadratic-band model, simplifying device design. We present adiabatic taper designs that attain <0.1% reflection in short lengths of 10 to 20 times the grating period. We show further that cascading two gratings compensates for signal dispersion and gives rise to a constant tunable time delay across bandwidths greater than 100GHz. Given typical loss values for silicon-on-insulator waveguides, we estimate that gratings can be designed to exhibit tunable delays in the picosecond range using current fabrication technology.

Dynamics of one- and two-dimensional fronts in a bistable equation with time-delayed global feedback: Propagation failure and control mechanisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boubendir, Yassine; Mendez, Vicenc; Rotstein, Horacio G.

2010-09-15

We study the evolution of fronts in a bistable equation with time-delayed global feedback in the fast reaction and slow diffusion regime. This equation generalizes the Hodgkin-Grafstein and Allen-Cahn equations. We derive a nonlinear equation governing the motion of fronts, which includes a term with delay. In the one-dimensional case this equation is linear. We study the motion of one- and two-dimensional fronts, finding a much richer dynamics than for the previously studied cases (without time-delayed global feedback). We explain the mechanism by which localized fronts created by inhibitory global coupling loose stability in a Hopf bifurcation as the delaymore » time increases. We show that for certain delay times, the prevailing phase is different from that corresponding to the system in the absence of global coupling. Numerical simulations of the partial differential equation are in agreement with the analytical predictions.« less

The Impact of Competing Time Delays in Stochastic Coordination Problems

NASA Astrophysics Data System (ADS)

Korniss, G.; Hunt, D.; Szymanski, B. K.

2011-03-01

Coordinating, distributing, and balancing resources in coupled systems is a complex task as these operations are very sensitive to time delays. Delays are present in most real communication and information systems, including info-social and neuro-biological networks, and can be attributed to both non-zero transmission times between different units of the system and to non-zero times it takes to process the information and execute the desired action at the individual units. Here, we investigate the importance and impact of these two types of delays in a simple coordination (synchronization) problem in a noisy environment. We establish the scaling theory for the phase boundary of synchronization and for the steady-state fluctuations in the synchronizable regime. Further, we provide the asymptotic behavior near the boundary of the synchronizable regime. Our results also imply the potential for optimization and trade-offs in stochastic synchronization and coordination problems with time delays. Supported in part by DTRA, ARL, and ONR.

Synchronization of unidirectionally delay-coupled chaotic oscillators with memory

NASA Astrophysics Data System (ADS)

Jaimes-Reátegui, Rider; Vera-Ávila, Victor P.; Sevilla-Escoboza, Ricardo; Huerta-Cuéllar, Guillermo; Castañeda-Hernández, Carlos E.; Chiu-Zarate, Roger; Pisarchik, Alexander N.

2016-11-01

We study synchronization of two chaotic oscillators coupled with time delay in a master-slave configuration and with delayed positive feedback in the slave oscillator which acts as memory. The dynamics of the slave oscillator is analyzed with bifurcation diagrams of the peak value of the system variable with respect to the coupling and feedback strengths and two delay times. For small coupling, when the oscillators' phases synchronize, memory can induce bistability and stabilize periodic orbits, whereas for stronger coupling it is not possible. The delayed feedback signal impairs synchronization, simultaneously enhancing coherence of the slave oscillator.

Using Video to Bridge the Gap Between Problem Behavior and a Delayed Time-out Procedure.

PubMed

Coppage, Sara; Meindl, James N

2017-09-01

Treatment plans focused on problem behavior often include punishment contingencies to decrease problem behavior. Immediate punishers are typically more effective than delayed punishers, but immediate delivery of a punisher is not always possible. Strategies need to be developed to increase the suppressive effects of delayed punishers. This study demonstrated the effectiveness of a treatment package involving replaying a video recording of problem behavior immediately before delivering a 15 min delayed time-out. This treatment package may prove to be an accessible and inexpensive strategy when using delayed punishers.

Spacecraft stability and control using new techniques for periodic and time-delayed systems

NASA Astrophysics Data System (ADS)

NAzari, Morad

This dissertation addresses various problems in spacecraft stability and control using specialized theoretical and numerical techniques for time-periodic and time-delayed systems. First, the effects of energy dissipation are considered in the dual-spin spacecraft, where the damper masses in the platform (?) and the rotor (?) cause energy loss in the system. Floquet theory is employed to obtain stability charts for different relative spin rates of the subsystem [special characters omitted] with respect to the subsystem [special characters omitted]. Further, the stability and bifurcation of delayed feedback spin stabilization of a rigid spacecraft is investigated. The spin is stabilized about the principal axis of the intermediate moment of inertia using a simple delayed feedback control law. In particular, linear stability is analyzed via the exponential-polynomial characteristic equations and then the method of multiple scales is used to obtain the normal form of the Hopf bifurcation. Next, the dynamics of a rigid spacecraft with nonlinear delayed multi-actuator feedback control are studied, where a nonlinear feedback controller using an inverse dynamics approach is sought for the controlled system to have the desired linear delayed closed-loop dynamics (CLD). Later, three linear state feedback control strategies based on Chebyshev spectral collocation and the Lyapunov Floquet transformation (LFT) are explored for regulation control of linear periodic time delayed systems. First , a delayed feedback control law with discrete delay is implemented and the stability of the closed-loop response is investigated in the parameter space of available control gains using infinite-dimensional Floquet theory. Second, the delay differential equation (DDE) is discretized into a large set of ordinary differential equations (ODEs) using the Chebyshev spectral continuous time approximation (CSCTA) and delayed feedback with distributed delay is applied. The third strategy involves use of both CSCTA and the reduced Lyapunov Floquet transformation (RLFT) in order to design a non-delayed feedback control law. The delayed Mathieu equation is used as an illustrative example in which the closed-loop response and control effort are compared for all three control strategies. Finally, three example applications of control of time-periodic astrodynamic systems, i.e. formation flying control for an elliptic Keplerian chief orbit, body-fixed hovering control over a tumbling asteroid, and stationkeeping in Earth-Moon L1 halo orbits, are shown using versions of the control strategies introduced above. These applications employ a mixture of feedforward and non-delayed periodic-gain state feedback for tracking control of natural and non-natural motions in these systems. A major conclusion is that control effort is minimized by employing periodic-gain (rather than constant-gain) feedback control in such systems.

Micromachined silicon acoustic delay line with 3D-printed micro linkers and tapered input for improved structural stability and acoustic directivity

NASA Astrophysics Data System (ADS)

Cho, Y.; Kumar, A.; Xu, S.; Zou, J.

2016-10-01

Recent studies have shown that micromachined silicon acoustic delay lines can provide a promising solution to achieve real-time photoacoustic tomography without the need for complex transducer arrays and data acquisition electronics. To achieve deeper imaging depth and wider field of view, a longer delay time and therefore delay length are required. However, as the length of the delay line increases, it becomes more vulnerable to structural instability due to reduced mechanical stiffness. In this paper, we report the design, fabrication, and testing of a new silicon acoustic delay line enhanced with 3D printed polymer micro linker structures. First, mechanical deformation of the silicon acoustic delay line (with and without linker structures) under gravity was simulated by using finite element method. Second, the acoustic crosstalk and acoustic attenuation caused by the polymer micro linker structures were evaluated with both numerical simulation and ultrasound transmission testing. The result shows that the use of the polymer micro linker structures significantly improves the structural stability of the silicon acoustic delay lines without creating additional acoustic attenuation and crosstalk. In addition, the improvement of the acoustic acceptance angle of the silicon acoustic delay lines was also investigated to better suppress the reception of unwanted ultrasound signals outside of the imaging plane. These two improvements are expected to provide an effective solution to eliminate current limitations on the achievable acoustic delay time and out-of-plane imaging resolution of micromachined silicon acoustic delay line arrays.

Gender and socio-cultural determinants of delay to diagnosis of TB in Bangladesh, India and Malawi.

PubMed

Gosoniu, G D; Ganapathy, S; Kemp, J; Auer, C; Somma, D; Karim, F; Weiss, M G

2008-07-01

Tuberculosis (TB) control programmes in Bangladesh, India and Malawi. To compare the interval from symptom onset to diagnosis of TB for men and women, and to assess socio-cultural and gender-related features of illness explaining diagnostic delay. Semi-structured Explanatory Model Interview Catalogue (EMIC) interviews were administered to 100 or more patients at each site, assessing categories of distress, perceived causes and help seeking. Based on time from initial symptoms to diagnosis of TB, patients were classified with problem delay (>90 days), timely diagnosis (< or =30 days) or moderate delay. EMIC interview data were analysed to explain problem delay. The median interval from symptom onset to diagnosis was longest in India and shortest in Malawi. With adjustment for confounding, female sex (Bangladesh), and status of married woman (India) and housewife (Malawi) were associated with problem delay. Prominent non-specific symptoms--chest pain (Bangladesh) and breathlessness (Malawi)--were also significant. Cough in India, widely associated with TB, was associated with timely diagnosis. Sanitation as a perceived cause linked to poor urban conditions was associated with delayed diagnosis in India. Specific prior help seeking with circuitous referral patterns was identified. The study identified gender- and illness-related features of diagnostic delay. Further research distinguishing patient and provider delay is needed.

When good pigeons make bad decisions: Choice with probabilistic delays and outcomes.

PubMed

Pisklak, Jeffrey M; McDevitt, Margaret A; Dunn, Roger M; Spetch, Marcia L

2015-11-01

Pigeons chose between an (optimal) alternative that sometimes provided food after a 10-s delay and other times after a 40-s delay and another (suboptimal) alternative that sometimes provided food after 10 s but other times no food after 40 s. When outcomes were not signaled during the delays, pigeons strongly preferred the optimal alternative. When outcomes were signaled, choices of the suboptimal alternative increased and most pigeons preferred the alternative that provided no food after the long delay despite the cost in terms of obtained food. The pattern of results was similar whether the short delays occurred on 25% or 50% of the trials. Shortening the 40-s delay to food sharply reduced suboptimal choices, but shortening the delay to no food had little effect. The results suggest that a signaled delay to no food does not punish responding in probabilistic choice procedures. The findings are discussed in terms of conditioned reinforcement by signals for good news. © Society for the Experimental Analysis of Behavior.

Robust passivity analysis for discrete-time recurrent neural networks with mixed delays

NASA Astrophysics Data System (ADS)

Huang, Chuan-Kuei; Shu, Yu-Jeng; Chang, Koan-Yuh; Shou, Ho-Nien; Lu, Chien-Yu

2015-02-01

This article considers the robust passivity analysis for a class of discrete-time recurrent neural networks (DRNNs) with mixed time-delays and uncertain parameters. The mixed time-delays that consist of both the discrete time-varying and distributed time-delays in a given range are presented, and the uncertain parameters are norm-bounded. The activation functions are assumed to be globally Lipschitz continuous. Based on new bounding technique and appropriate type of Lyapunov functional, a sufficient condition is investigated to guarantee the existence of the desired robust passivity condition for the DRNNs, which can be derived in terms of a family of linear matrix inequality (LMI). Some free-weighting matrices are introduced to reduce the conservatism of the criterion by using the bounding technique. A numerical example is given to illustrate the effectiveness and applicability.

Stochastic nonlinear time series forecasting using time-delay reservoir computers: performance and universality.

PubMed

Grigoryeva, Lyudmila; Henriques, Julie; Larger, Laurent; Ortega, Juan-Pablo

2014-07-01

Reservoir computing is a recently introduced machine learning paradigm that has already shown excellent performances in the processing of empirical data. We study a particular kind of reservoir computers called time-delay reservoirs that are constructed out of the sampling of the solution of a time-delay differential equation and show their good performance in the forecasting of the conditional covariances associated to multivariate discrete-time nonlinear stochastic processes of VEC-GARCH type as well as in the prediction of factual daily market realized volatilities computed with intraday quotes, using as training input daily log-return series of moderate size. We tackle some problems associated to the lack of task-universality for individually operating reservoirs and propose a solution based on the use of parallel arrays of time-delay reservoirs. Copyright © 2014 Elsevier Ltd. All rights reserved.

Numerical simulation of time delay Interferometry for LISA with one arm dysfunctional

NASA Astrophysics Data System (ADS)

Ni, Wei-Tou; Dhurandhar, Sanjeev V.; Nayak, K. Rajesh; Wang, Gang

In order to attain the requisite sensitivity for LISA, laser frequency noise must be suppressed below the secondary noises such as the optical path noise, acceleration noise etc. In a previous paper(a), we have found an infinite family of second generation analytic solutions of time delay interferometry and estimated the laser noise due to residual time delay semi-analytically from orbit perturbations due to earth. Since other planets and solar-system bodies also perturb the orbits of LISA spacecraft and affect the time delay interferometry, we simulate the time delay numerically in this paper. To conform to the actual LISA planning, we have worked out a set of 10-year optimized mission orbits of LISA spacecraft using CGC3 ephemeris framework(b). Here we use this numerical solution to calculate the residual errors in the second generation solutions upto n 3 of our previous paper, and compare with the semi-analytic error estimate. The accuracy of this calculation is better than 1 m (or 30 ns). (a) S. V. Dhurandhar, K. Rajesh Nayak and J.-Y. Vinet, time delay Interferometry for LISA with one arm dysfunctional (b) W.-T. Ni and G. Wang, Orbit optimization for 10-year LISA mission orbit starting at 21 June, 2021 using CGC3 ephemeris framework

Noise and time delay induce critical point in a bistable system

NASA Astrophysics Data System (ADS)

Zhang, Jianqiang; Nie, Linru; Yu, Lilong; Zhang, Xinyu

2014-07-01

We study relaxation time Tc of time-delayed bistable system driven by two cross-correlated Gaussian white noises that one is multiplicative and the other is additive. By means of numerical calculations, the results indicate that: (i) Combination of noise and time delay can induce two critical points about the relaxation time at some certain noise cross-correlation strength λ under the condition that the multiplicative intensity D equals to the additive noise intensity α. (ii) For each fixed D or α, there are two symmetrical critical points which locates in the regions of positive and negative correlations, respectively. Namely, as λ equals to the critical value λc, Tc is independent of the delay time and the result of Tc versus τ is a horizontal line, but as |λ|>|λc| (or |λ|<|λc|), the relaxation time Tc monotonically increases (or decreases) with the delay time increasing. (iii) In the presence of D = α, the change of λc with D is two symmetrical curves about the axis of λc = 0, and the critical value λc is close to zero for a smaller D, which approaches to +1 or -1 for a greater D.

High pressure shock tube ignition delay time measurements during oxy-methane combustion with high levels of CO 2 dilution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pryor, Owen; Barak, Samuel; Lopez, Joseph

For this study, ignition delay times and methane species time-histories were measured for methane/O 2 mixtures in a high CO 2 diluted environment using shock tube and laser absorption spectroscopy. The experiments were performed between 1300 K and 2000 K at pressures between 6 and 31 atm. The test mixtures were at an equivalence ratio of 1 with CH 4 mole fractions ranging from 3.5% -5% and up to 85% CO 2 with a bath of argon gas as necessary. The ignition delay times and methane time histories were measured using pressure, emission, and laser diagnostics. Predictive ability of twomore » literature kinetic mechanisms (GRI 3.0 and ARAMCO Mech 1.3) was tested against current data. In general, both mechanisms performed reasonably well against measured ignition delay time data. The methane time-histories showed good agreement with the mechanisms for most of the conditions measured. A correlation for ignition delay time was created taking into the different parameters showing that the ignition activation energy for the fuel to be 49.64 kcal/mol. Through a sensitivity analysis, CO 2 is shown to slow the overall reaction rate and increase the ignition delay time. To the best of our knowledge, we present the first shock tube data during ignition of methane/CO 2/O 2 under these conditions. In conclusion, current data provides crucial validation data needed for development of future kinetic mechanisms.« less

High pressure shock tube ignition delay time measurements during oxy-methane combustion with high levels of CO 2 dilution

DOE PAGES

Pryor, Owen; Barak, Samuel; Lopez, Joseph; ...

2017-03-30

For this study, ignition delay times and methane species time-histories were measured for methane/O 2 mixtures in a high CO 2 diluted environment using shock tube and laser absorption spectroscopy. The experiments were performed between 1300 K and 2000 K at pressures between 6 and 31 atm. The test mixtures were at an equivalence ratio of 1 with CH 4 mole fractions ranging from 3.5% -5% and up to 85% CO 2 with a bath of argon gas as necessary. The ignition delay times and methane time histories were measured using pressure, emission, and laser diagnostics. Predictive ability of twomore » literature kinetic mechanisms (GRI 3.0 and ARAMCO Mech 1.3) was tested against current data. In general, both mechanisms performed reasonably well against measured ignition delay time data. The methane time-histories showed good agreement with the mechanisms for most of the conditions measured. A correlation for ignition delay time was created taking into the different parameters showing that the ignition activation energy for the fuel to be 49.64 kcal/mol. Through a sensitivity analysis, CO 2 is shown to slow the overall reaction rate and increase the ignition delay time. To the best of our knowledge, we present the first shock tube data during ignition of methane/CO 2/O 2 under these conditions. In conclusion, current data provides crucial validation data needed for development of future kinetic mechanisms.« less

Finite-time hybrid projective synchronization of the drive-response complex networks with distributed-delay via adaptive intermittent control

NASA Astrophysics Data System (ADS)

Cheng, Lin; Yang, Yongqing; Li, Li; Sui, Xin

2018-06-01

This paper studies the finite-time hybrid projective synchronization of the drive-response complex networks. In the model, general transmission delays and distributed delays are also considered. By designing the adaptive intermittent controllers, the response network can achieve hybrid projective synchronization with the drive system in finite time. Based on finite-time stability theory and several differential inequalities, some simple finite-time hybrid projective synchronization criteria are derived. Two numerical examples are given to illustrate the effectiveness of the proposed method.

Switching Characteristics of Ferroelectric Transistor Inverters

NASA Technical Reports Server (NTRS)

Laws, Crystal; Mitchell, Coey; MacLeod, Todd C.; Ho, Fat D.

2010-01-01

This paper presents the switching characteristics of an inverter circuit using a ferroelectric field effect transistor, FeFET. The propagation delay time characteristics, phl and plh are presented along with the output voltage rise and fall times, rise and fall. The propagation delay is the time-delay between the V50% transitions of the input and output voltages. The rise and fall times are the times required for the output voltages to transition between the voltage levels V10% and V90%. Comparisons are made between the MOSFET inverter and the ferroelectric transistor inverter.

Wigner time-delay distribution in chaotic cavities and freezing transition.

PubMed

Texier, Christophe; Majumdar, Satya N

2013-06-21

Using the joint distribution for proper time delays of a chaotic cavity derived by Brouwer, Frahm, and Beenakker [Phys. Rev. Lett. 78, 4737 (1997)], we obtain, in the limit of the large number of channels N, the large deviation function for the distribution of the Wigner time delay (the sum of proper times) by a Coulomb gas method. We show that the existence of a power law tail originates from narrow resonance contributions, related to a (second order) freezing transition in the Coulomb gas.

Comparison of delayed versus immediate pushing during second stage of labor for nulliparous women with epidural anesthesia.

PubMed

Gillesby, Erica; Burns, Suzan; Dempsey, Amy; Kirby, Shirley; Mogensen, Kami; Naylor, Kelly; Petrella, Joann; Vanicelli, Rebecca; Whelan, Breon

2010-01-01

To determine if the use of delayed pushing after the onset of the second stage of labor decreases the time of active pushing and decreases maternal fatigue. Randomized clinical trial. Labor and delivery unit of a not-for-profit community hospital. Convenience sample of nulliparous laboring women with epidural anesthesia. Immediate or delayed pushing (2 hours) during the second stage of labor at the time of complete cervical dilatation. The length of pushing, total length of the second stage, and maternal fatigue. A total of 77 women were studied (immediate pushing group=39; delayed pushing=38). The immediate pushing group averaged 94 (± 57) minutes in active pushing, while the delayed pushing group averaged 68 (± 46) minutes, a statistically significant difference (p=.04). No significant differences were found in fatigue scores between the immediate and delayed pushing groups (p>.05). We found that by delaying the onset of active pushing for 2 hours after the beginning of the second stage of labor, the time that nulliparous women with epidural anesthesia spent in active pushing was significantly decreased by 27%. Although the delayed pushing group rested for up to 2 hours, the total time in the second stage of labor averaged only 59 minutes longer than the immediate pushing group. © 2010 AWHONN, the Association of Women's Health, Obstetric and Neonatal Nurses.

Timing and delay in children vaccination; evaluation of expanded program of immunization in outskirt of Iranian cities.

PubMed

Rejali, Mehri; Mohammadbeigi, Abolfazl; Mokhtari, Mohsen; Zahraei, Seyed Mohsen; Eshrati, Babak

2015-01-01

Most studies evaluated the vaccine coverage, but the time of vaccination is important as coverage. This study was conducted to evaluate the Expanded Program of Immunization (EPI) in outskirt of Iranian cities regarding to incidence of delay vaccination among children less than 4 years. This cross sectional descriptive study was conducted among children 24-47 months old, living in the suburbs of five metropolises of Iran. Totally, 3610 eligible children selected with proportioned cluster sampling method and data of vaccination card extracted after interview with child parents. Delayed incidence rate reported and predictive factors assessed by Chi square test and Multivariate logistic regression. Overall, 56.6% to 93.2% vaccines were administered out of time. Delayed vaccination incidence with more than one-week delay varies from 5.5% to 74.9% for polio at birth and MMR2 at 18 month, respectively. Mother's educational level and birth order were the most important predictors of delayed vaccination. Incidence of delayed vaccination was enlarged by increasing birth order and decreased in lower educated mothers. Incidence rate of delayed vaccination is more than expectation. Regarding to high coverage vaccines in Iran, heath officers and health policy makers should attempt for on-time vaccination beside of high immunization coverage especially in slum areas with more concentrated immigrants due to low literature and crowded families.

Research on the Applicable Method of Valuation of Pure Electric Used vehicles

NASA Astrophysics Data System (ADS)

Cai, yun; Tan, zhengping; Wang, yidong; Mao, pan

2018-03-01

With the rapid growth in the ownership of pure electric vehicles, the research on the valuation of used electric vehicles has become the key to the development of the pure electric used vehicle market. The paper analyzed the application of the three value assessment methods, current market price method, capitalized earning method and replacement cost method, in pure electric used vehicles, and draws a conclusion that the replacement cost method is more suitable for pure electric used car. At the same time, the article also conducted a parametric correction exploration research, aiming at the characteristics of pure electric vehicles and replacement cost of the constituent factors. Through the analysis of the applicability parameters of physical devaluation, functional devaluation and economic devaluation, the revised replacement cost method can be used for the valuation of purely used electric vehicles for private use.

The Strong Lensing Time Delay Challenge (2014)

NASA Astrophysics Data System (ADS)

Liao, Kai; Dobler, G.; Fassnacht, C. D.; Treu, T.; Marshall, P. J.; Rumbaugh, N.; Linder, E.; Hojjati, A.

2014-01-01

Time delays between multiple images in strong lensing systems are a powerful probe of cosmology. At the moment the application of this technique is limited by the number of lensed quasars with measured time delays. However, the number of such systems is expected to increase dramatically in the next few years. Hundred such systems are expected within this decade, while the Large Synoptic Survey Telescope (LSST) is expected to deliver of order 1000 time delays in the 2020 decade. In order to exploit this bounty of lenses we needed to make sure the time delay determination algorithms have sufficiently high precision and accuracy. As a first step to test current algorithms and identify potential areas for improvement we have started a "Time Delay Challenge" (TDC). An "evil" team has created realistic simulated light curves, to be analyzed blindly by "good" teams. The challenge is open to all interested parties. The initial challenge consists of two steps (TDC0 and TDC1). TDC0 consists of a small number of datasets to be used as a training template. The non-mandatory deadline is December 1 2013. The "good" teams that complete TDC0 will be given access to TDC1. TDC1 consists of thousands of lightcurves, a number sufficient to test precision and accuracy at the subpercent level, necessary for time-delay cosmography. The deadline for responding to TDC1 is July 1 2014. Submissions will be analyzed and compared in terms of predefined metrics to establish the goodness-of-fit, efficiency, precision and accuracy of current algorithms. This poster describes the challenge in detail and gives instructions for participation.

Tolerable hearing-aid delays: IV. effects on subjective disturbance during speech production by hearing-impaired subjects.

PubMed

Stone, Michael A; Moore, Brian C J

2005-04-01

We assessed the effects of time delay in a hearing aid on subjective disturbance and reading rates while the user of the aid was speaking, using hearing-impaired subjects and real-time processing. The time delay was constant across frequency. A digital signal processor was programmed as a four-channel, fast-acting, wide-dynamic-range compression hearing aid. One of four delays could be selected on the aid to produce a total delay of 13, 21, 30, or 40 msec between microphone and receiver. Twenty-five subjects, mostly with near-symmetric hearing impairment of cochlear origin, were fitted bilaterally with behind-the-ear aids connected to the processor. The aids were programmed with insertion gains prescribed by the CAMEQ loudness equalization procedure for each subject and ear. Subjects were asked to read aloud from scripts: speech production rates were measured and subjective ratings of the disturbance of the delay were obtained. Subjects required some training to recognize the effects of the delay to rate it consistently. Subjective disturbance increased progressively with increasing delay and was a nonmonotonic function of low-frequency hearing loss. Subjects with mild or severe low-frequency hearing loss were generally less disturbed by the delay than those with moderate loss. Disturbance ratings tended to decrease over successive tests. Word production rates were not significantly affected by delay over the range of delays tested. The results follow a pattern similar to those presented in , obtained using a simulation of hearing loss and normally hearing subjects, except for the nonmonotonic variation of disturbance with low-frequency hearing loss. We hypothesize that disturbance is maximal when the levels in the ear canal of the low-frequency components are similar for the unaided and aided sounds. A rating of 3, which is probably just acceptable, was obtained for delays ranging from 14 to 30 msec, depending on the hearing loss. Some acclimatization to the subjective disturbance occurred over a time scale of about 1 hour.

The devil is in the details: retention of recipient group A type 5 years after a successful allogeneic bone marrow transplant from a group O donor.

PubMed

Cooling, Laura L W; Herrst, Michelle; Hugan, Sherri L

2018-01-01

ABO-incompatible (ABOi) hematopoietic stem cell transplants (HSCTs) can present challenges in the blood bank. During transplantation, patients receive components that are ABO-compatible with both the donor graft and recipient; this practice can strain group O red blood cell (RBC) inventories.1 In addition, there are risks for acute hemolysis at the time of infusion and in the early post-transplant period.1,2 In ABO major-incompatible bone marrow HSCTs, which contain significant quantities of donor RBCs that are ABOi with recipient plasma, it is common to perform a RBC depletion of the bone marrow in an effort to minimize hemolysis at the time of infusion.2 Furthermore, patients with high-titer ABO antibodies may undergo a prophylactic, pre-transplant plasma exchange to further reduce the risk of acute hemolysis, delayed RBC engraftment, and pure RBC aplasia.2-4 ABO minor-incompatible HSCTs, in which donor plasma is ABOi with the recipient, have less risk for hemolysis at the time of infusion but can result in transient hemolysis approximately 10-21 days post-transplant, especially in patients undergoing nonmyeloablative HSCT and/or patients who have not received methotrexate for graft-versus-host-disease (GVHD) prophylaxis.1-4 In these patients, viable donor B-lymphocytes in the graft may expand and produce ABO antibodies capable of hemolyzing patient RBCs.

Performance evaluation of a six-axis generalized force-reflecting teleoperator

NASA Technical Reports Server (NTRS)

Hannaford, B.; Wood, L.; Guggisberg, B.; Mcaffee, D.; Zak, H.

1989-01-01

Work in real-time distributed computation and control has culminated in a prototype force-reflecting telemanipulation system having a dissimilar master (cable-driven, force-reflecting hand controller) and a slave (PUMA 560 robot with custom controller), an extremely high sampling rate (1000 Hz), and a low loop computation delay (5 msec). In a series of experiments with this system and five trained test operators covering over 100 hours of teleoperation, performance was measured in a series of generic and application-driven tasks with and without force feedback, and with control shared between teleoperation and local sensor referenced control. Measurements defining task performance included 100-Hz recording of six-axis force/torque information from the slave manipulator wrist, task completion time, and visual observation of predefined task errors. The task consisted of high precision peg-in-hole insertion, electrical connectors, velcro attach-de-attach, and a twist-lock multi-pin connector. Each task was repeated three times under several operating conditions: normal bilateral telemanipulation, forward position control without force feedback, and shared control. In shared control, orientation was locally servo controlled to comply with applied torques, while translation was under operator control. All performance measures improved as capability was added along a spectrum of capabilities ranging from pure position control through force-reflecting teleoperation and shared control. Performance was optimal for the bare-handed operator.

Testing Delays Resulting in Increased Identification Accuracy in Line-Ups and Show-Ups.

ERIC Educational Resources Information Center

Dekle, Dawn J.

1997-01-01

Investigated time delays (immediate, two-three days, one week) between viewing a staged theft and attempting an eyewitness identification. Compared lineups to one-person showups in a laboratory analogue involving 412 subjects. Results show that across all time delays, participants maintained a higher identification accuracy with the showup…