Differences In Relative Timing Research Articles

Scintillation Properties of Ba$_{x}$Sr$_{1 - {x}}$Cl$_{2}$ Single Crystals

In this paper, we present scintillation properties of the new developed single crystals of BaxSr1-xCl2 for different concentration of x. We manufactured Ba0.12Sr0.88Cl2, Ba0.20Sr0.80Cl2, Ba0.22Sr0.78Cl2 crystals, and CsI(Tl) crystal as reference by using the Czochralski method. The crystals were cut into a size of 5 times 10 times 10 mm3. The X-ray diffraction technique was used to verify the structure of crystals. The emission spectra were measured with X-ray excitation at room temperature. Scintillation properties of the crystals such as pulse height spectra, energy resolution, alpha/beta ratio, relative light output, proportionality, and fluorescence decay time were measured with the various radioactive gamma sources at room temperature. The light output of these crystals were compared with that of the CsI(Tl) crystal. The differences in relative light outputs, energy resolutions, and decay times among these crystals were studied in detail.

Phrase boundary effects on the temporal kinematics of sequential tongue tip consonants

This study evaluates the effects of phrase boundaries on the intra- and intergestural kinematic characteristics of blended gestures, i.e., overlapping gestures produced with a single articulator. The sequences examined are the juncture geminate [d(#)d], the sequence [d(#)z], and, for comparison, the singleton tongue tip gesture in [d(#)b]. This allows the investigation of the process of gestural aggregation [Munhall, K. G., and Lofqvist, A. (1992). "Gestural aggregation in speech: laryngeal gestures," J. Phonetics 20, 93-110] and the manner in which it is affected by prosodic structure. Juncture geminates are predicted to be affected by prosodic boundaries in the same way as other gestures; that is, they should display prosodic lengthening and lesser overlap across a boundary. Articulatory prosodic lengthening is also investigated using a signal alignment method of the functional data analysis framework [Ramsay, J. O., and Silverman, B. W. (2005). Functional Data Analysis, 2nd ed. (Springer-Verlag, New York)]. This provides the ability to examine a time warping function that characterizes relative timing difference (i.e., lagging or advancing) of a test signal with respect to a given reference, thus offering a way of illuminating local nonlinear deformations at work in prosodic lengthening. These findings are discussed in light of the pi-gesture framework of Byrd and Saltzman [(2003) "The elastic phrase: Modeling the dynamics of boundary-adjacent lengthening," J. Phonetics 31, 149-180].

Localization of Directional Sound Sources Supported by A Priori Information of the Acoustic Environment

Speaker localization with microphone arrays has received significant attention in the past decade as a means for automated speaker tracking of individuals in a closed space for videoconferencing systems, directed speech capture systems, and surveillance systems. Traditional techniques are based on estimating the relative time difference of arrivals (TDOA) between different channels, by utilizing crosscorrelation function. As we show in the context of speaker localization, these estimates yield poor results, due to the joint effect of reverberation and the directivity of sound sources. In this paper, we present a novel method that utilizes a priori acoustic information of the monitored region, which makes it possible to localize directional sound sources by taking the effect of reverberation into account. The proposed method shows significant improvement of performance compared with traditional methods in "noise-free" condition. Further work is required to extend its capabilities to noisy environments.

Predictable real-time software synthesis

Formal theories for real-time systems (such as timed process algebra, timed automata and timed petri nets) have gained great success in the modeling of concurrent timing behavior and in the analysis of real-time properties. However, due to the ineliminable timing differences between a model and its realization, synthesizing a software realization from a model in a predictable way is still a challenging research topic. In this article, we tackle this problem by solving a set of sub-problems. The solution is based on the theoretical results for property prediction proposed in Huang et al. (2003, Real-time property preservation in approximations of timed systems. In: Proceedings of 1st ACM and IEEE international conference on formal methods and models for codesign. IEEE Computer Society, Los Alamitos, pp 163–171) and Huang (2005, Predictability in real-time system design. PhD thesis, Eindhoven University of Technology, The Netherlands), where quantitative property relations are established between two absolute/relative “close” real-time systems. This theory basically implies that if two systems are “close”, they enjoy “similar” properties. These results cannot be directly applied in practice though, because a model and its realization typically have infinitely large absolute and relative timing differences. We show that this infinite time gap can be bridged through a sequence of carefully constructed intermediate time domains. Then the property-prediction results can be applied to any pair of adjacent time domains in the sequence. Consequently, real-time properties of the implementation can be predicted from the model. We propose two parameterized hypotheses to characterize the timing differences in the sequence and to guide a correctness-preserving design process. It is shown that these hypotheses can be incorporated in a concrete tool set. We demonstrate the feasibility of the predictable synthesis approach through the design of a railroad crossing system.

Measurement-Based Analysis of Delay Variation Induced by Dynamic Power Supply Noise

Accurate on-chip 100-ps/100-μV waveform measurements of signal transition in a large-scale digital integrated circuit clearly demonstrates the correlation of dynamic delay variation with power supply noise waveforms. In addition to the linear dependence of delay increase with the height of static IR drop, the distortion of a signal waveform during a logic transition that is induced by dynamic power supply noise causes significant delay variation. However, an analysis reveals that average modeling of dynamic power supply noise, which is often used in conventional simulation techniques, cannot match the experimentally measured values. Our proposed circuit simulation technique, which incorporates time-domain power supply noise waveform macro models along with parasitic impedance networks, reproduces the delay variation well, even with a relative timing difference among different clock domains. Such basic knowledge can be applied in precise delay calculations that consider dynamic power supply noise, a crucial factor in deep sub-100-nm LSI design.

Adaptive Input Shaping for Nonlinear Systems: A Case Study

Input shaping is a technique that seeks to reduce residual vibrations of lightly damped systems through modification of the command input to the system. Although several input shaping techniques have been derived primarily from linear system theory, theoretical results are hard to be traced for their application to nonlinear systems. In most of the reported cases, a fixed shaper is designed based on the linearized version around an operating point of the nonlinear system. In this paper, an adaptive form of the input shaper is proposed for a class of nonlinear lightly damped systems. The adaptive shaper adjusts the magnitude and relative time difference between its impulses according to the instant frequency and damping of the linearized systems. The efficacy of the proposed scheme and its comparison to a fixed shaper is investigated through its application to a pendulum system. The adaptive shaper’s parameters vary according to the pendulum’s angle. The illustrative examples indicate the deficiencies of the fixed case and demonstrate the efficacy of the designed controller.

Surface electrode placement affects the EMG recordings of the quadriceps muscles

Objectives This study examined the EMG activities of the medial and lateral vasti muscles with four different surface electrode positions during isometric knee extension and knee perturbation. Design Repeated measures design. Setting Orthopaedic rehabilitation laboratory of a university. Participants Eight able-bodied non-athletic male volunteers. Main outcome measures The relative onset time difference in milliseconds of vastus medialis obliquus (VMO) and vastus lateralis (VL) during knee perturbation, and the normalized EMG amplitude in root-mean-square ratio of VMO:VL during submaximal isometric knee extension were analyzed using repeated measures ANOVA. Results Different electrode positions on VL resulted in different VMO-VL onset time ( p = 0.002 ) and normalized VMO:VL activity ratios ( p = 0.002 , 0.014). Conclusions The position of surface electrodes has significantly affected the EMG readings of the vasti muscles. This finding has vital clinical implications for the application of EMG measurement and biofeedback training for the rehabilitation of the vasti muscles.

Comparison of Class I and Class II Treatment Duration Among Three Different Orthodontic Practices

The purpose of this investigation was to assess the relative treatment time difference (months/appointments) between Class II Division 1 patients and Class I patients from 3 different orthodontic offices. In addition, we also compared the estimated treatment length with the actual treatment length to determine how accurate the orthodontists were in predicting treatment duration. A total sample of 237 patients representing 3 observational groups (Angle Class I nonextraction, and Class II Division I extraction and nonextraction) were selected from the active retention files of each office. Pretreatment ANB angle, pretreatment overjet, and the pre- and posttreatment PAR scores (weighted) were measured. The results of this investigation indicated that among the 3 orthodontic offices, Class II Division 1 cases took an average of 5 more months than Class I cases. There was no significant treatment time difference (months) between the Class II extraction and nonextraction groups. Class II treatments including Herbst therapy were significantly longer (around 8 months) than treatments including headgears. The treatment length in 4 of the 9 observational groups was significantly underestimated and our data demonstrated no association of pretreatment PAR scores and percentage PAR reduction with treatment duration.

Waveform Measurement of Ultra-Short Optical Pulses Based on Two-Photon Absorption in Si-Image Sensor

We demonstrate a novel waveform mesurement system of ultra-short optical pulses based on the two-photon absorption process in a Si-image sensor. Using an interferometer with a tilt mirror in the reference path, the relative time difference between the signal and reference pulses is spatially distributed on the Si-image sensor, so the intensity auto-correlation is monitored as an image at a time without using moving parts. This system can create or remove an interference fringe pattern overlapped on the auto-correlation image by controlling the polarization states of the laser pulse, which is useful for measuring the crossing angle between the signal and reference beams as well as avoiding contamination of the interference fringe into the auto-correlation image. We successfully measured optical pulses less than 100 fs from a fiber ring laser with a temporal resolution of 0.4 fs. The obtained waveform agreed well with that observed with a conventional second harmonic generation (SHG) based auto-correlator.

Risk factors for Kaposi's sarcoma among HHV‐8 seropositive homosexual men with AIDS

Kaposi's sarcoma (KS) is a frequent complication of the acquired immunodeficiency syndrome (AIDS) in homosexual men. Risk factors for developing this malignancy are uncertain, other than immunosuppression and coinfection with human herpesvirus 8 (HHV-8). We therefore examined factors associated with KS in a cross-sectional analysis of 99 cases among 503 HHV-8 seropositive homosexual men with AIDS. Data were collected by computer-assisted personal interviews and medical chart reviews. HHV-8 seroreactivity was determined by enzyme-linked immunosorbent assay for antibodies against HHV-8 K8.1 glycoprotein. KS was significantly less common in blacks compared to whites [risk ratio (RR) = 0.4; 95% CI = 0.2 =0.8] and more common in subjects who had completed college (RR = 1.7; 95% CI = 1.1-2.7) or had annual income greater than dollar 30,000 (RR = 1.5; 95% CI = 1.1-2.2). KS was less common in cigarette smokers (RR = 0.6; 95% CI = 0.5-0.9) and users of crack cocaine (RR = 0.4; 95% CI = 0.1-0.8). KS was less common in bisexual men compared to men who were exclusively homosexual (estimated RR = 0.6; 95% CI = 0.4-0.9) and inversely associated with number of female partners. KS was also less common in men who had received pay for sex (RR = 0.6; 95% CI = 0.4-1.0). These cross-sectional associations could be biased by potential differences in relative timing of HHV-8 and HIV infection, a postulated determinant of KS risk. Alternatively, our findings may reflect factors protective against KS in individuals infected with HHV-8. Future research should focus on identifying practical measures for countering KS that do not increase the risk of other diseases.

Kinematic and dynamic processes for the control of pointing movements in humans revealed by short-term exposure to microgravity

The generation of accurate motor commands requires implicit knowledge of both limb and environmental dynamics. The action of gravity on moving limb segments must be taken into account within the motor command, and may affect the limb trajectory chosen to accomplish a given motor task. Exactly how the CNS deals with these gravitoinertial forces remains an open question. Does the CNS measure gravitational forces directly, or are they accommodated in the motor plan by way of internal models of physical laws? In this study five male subjects participated. We measured kinematic and dynamic parameters of upward and downward arm movements executed at two different speeds, in both normal Earth gravity and in the weightless conditions of parabolic flight. Exposure to microgravity affected velocity profiles for both directions and speeds. The shape of velocity profiles (the ratio of maximum to mean velocity) and movement duration both showed transient perturbations initially in microgravity, but returned to normal gravity values with practice in 0× g. Differences in relative time to peak velocity between upward versus downward movements, persisted for all trial performed in weightlessness. These differences in kinematic profiles and in the torque profiles used to produce them, diminished, however, with practice in 0× g. These findings lead to the conclusion that the CNS explicitly represents gravitational and inertial forces in the internal models used to generate and execute arm movements. Furthermore, the results suggest that the CNS adapts motor plans to novel environments on different time scales; dynamics adapt first to reproduce standard kinematics, and then kinematics patterns are adapted to optimize dynamics.

Análisis de la marcha en la enfermedad de Parkinson y su respuesta al tratamiento dopaminérgico

The objective of this study was to analyze the gait abnormalities in patients with idiopathic Parkinson's disease (PD), and their response to dopaminergic treatment. 15 patients and 15 healthy age-matched subjects were included for comparison between pathologic and "normal" gait, and 24 PD patients were included to assess the effects of treatment. Gait analysis was achieved with a new 3D-photogrammetry system. Patients had significative lower velocity, stride length, step length and hip and knee ranges when compared with control subjects. There were no differences in cadence, step width and relative times of gait-cycle. There were no differences in the patients' gait variables after administration of a dopaminergic medication. Gait analysis allows quantification of gait disturbances in patients with PD and the potential effects of treatment. The results of this study suggest a certain degree of "levodopa-resistance" in gait in these patients.

Time-Delay Estimation via Linear Interpolation and Cross Correlation

Time-delay estimation (TDE), which aims at measuring the relative time difference of arrival (TDOA) between different channels is a fundamental approach for identifying, localizing, and tracking radiating sources. Recently, there has been a growing interest in the use of TDE based locator for applications such as automatic camera steering in a room conferencing environment where microphone sensors receive not only the direct-path signal, but also attenuated and delayed replicas of the source signal due to reflections from boundaries and objects in the room. This multipath propagation effect introduces echoes and spectral distortions into the observation signal, termed as reverberation, which severely deteriorates a TDE algorithm in its performance. This paper deals with the TDE problem with emphasis on combating reverberation using multiple microphone sensors. The multichannel cross correlation coefficient (MCCC) is rederived here, in a new way, to connect it to the well-known linear interpolation technique. Some interesting properties and bounds of the MCCC are discussed and a recursive algorithm is introduced so that the MCCC can be estimated and updated efficiently when new data snapshots are available. We then apply the MCCC to the TDE problem. The resulting new algorithm can be treated as a natural generalization of the generalized cross correlation (GCC) TDE method to the multichannel case. It is shown that this new algorithm can take advantage of the redundancy provided by multiple microphone sensors to improve TDE against both reverberation and noise. Experiments confirm that the relative time-delay estimation accuracy increases with the number of sensors.

Small-scale variations in seismic anisotropy near Kimberley, South Africa

SUMMARY We have exploited a new data set of broad-band seismic waveforms recorded near the region of Kimberley, South Africa to place new constraints on seismic anisotropy in an area of extensive mantle modification within an Archaean cratonic setting. The Kimberley region is significant in that it represents Archaean cratonic mantle that has been studied extensively via petrologic, geochemical and seismic means, and provides a unique opportunity to meld the results of a broad range of data sets to examine processes of crust and mantle deformation. Shear wave splitting observations using SKS phases recorded by a dense broad-band seismic array in the Kimberley region exhibit consistent fast polarization directions of ∼NE‐SW and splitting times that range from 0.15 s in the SE to nearly 0.75 s in the NW regions of the array. Multichannel cross-correlation of relative arrival times of teleseismic SKS phases across the array reveals clear azimuthal variations and a relative arrival-time range comparable to the shear wave splitting delay-time range. A like analysis of teleseismic PKPdf phases does not exhibit significant differences in relative arrival times across the array. The combined relative arrival time and splitting analyses indicate that a significant change in the strength of anisotropic structure is required across the region. Our results are most consistent with a model in which variations in seismic anisotropy near the Kimberley region are constrained to the lithosphere with an average anisotropic strength of ∼1.8 per cent, extend to depths no greater than 150 km and are primarily controlled by a significant change in the strength of anisotropy within the lateral bounds of the seismic array. This inferred structural boundary is near the location of the ca 2.9 Gyr old Colesberg magnetic lineament, a prominent aeromagnetic feature interpreted as the primary suture zone joining the eastern Meso-Archaean and western Neo-Archaean blocks of the Kaapvaal craton. The proposed boundary is also located within the southern exposure of the ca 2.7 Gyr old Ventersdorp volcanic-sedimentary sequence, a key continental rifting feature in the region. We hypothesize that the observed seismic anisotropy is the result of straininduced lattice-preferred orientation of olivine caused by the amalgamation and deformation of the eastern and western blocks of the Kaapvaal craton. This collisional process mechanically weakened the region to generate the observed mantle fabric, which was exploited by significant rifting events that may have subsequently enhanced the regional fabric. This model is also consistent with SKS splitting results for the whole of southern Africa, which suggest either weak anisotropic or isotropic mantle structure in the eastern Kaapvaal and coherent mantle anisotropy across much of the western Kaapvaal. Our results support the notion that seismic anisotropy beneath Archaean continental regions is not created (or, alternatively, not preserved) during initial continental formation, but is instead generated during subsequent significant mantle-deforming events.

Production and characterization of antibodies for the specific determination of the opioid peptide Met5-Enkephalin-Arg6-Phe7

Finn A, Ågren G, Bjellerup P, Vedin I, Lundeberg T. Production and characterization of antibodies for the specific determination of the opioid peptide Met5-Enkephalin-Arg6-Phe7. 2004; 64: 49-56.Endogenous opioids serve as modulators of neuroendocrine and immune system processes, the investigation of which calls for high-specificity radioimmunoassays (RIAs). This study focuses on the development and use of a specific radioimmunoassay for the opioid peptide Met5-Enkephalin-Arg6-Phe7 (MEAP), the C-terminus part of proenkepbalin A. Antibodies were raised in four rabbits and investigated in terms of titre, avidity and specificity, followed by finding ideal conditions for these antibodies in RIA. MEAP concentrations were determined in crude extracts of rat hypothalamus, dorsal root ganglia, adrenals and ankle using this standardized assay after an oxidizing process. At reverse-phase high-pressure liquid chromatography (HPLC), the position of immunoreactive material from rat hypothalamus eluted as two peaks out of which one was compatible with that of synthetic MEAP. All rabbits exhibited individual differences in relative immune response and time of its onset. The avidity constant was 10 times higher on a molar basis for ab 4108 compared with ab 4182. There was no cross-reactivity for ab 4182 to related peptides, such as enkephalins and dynorphin B, and negligible background values for ab 4108. The relative levels of immunoreactive MEAP from the CNS versus peripheral tissues contrasted in accordance with current knowledge. It is suggested that reports with RIA results should include characterization of antibodies, extraction procedures, standard curves and compositions of buffers. Furthermore, the results should preferably be expressed in relation to total protein content.

Calibration of 3D positioning in a Ge cross-strip detector

In preparation for the Nuclear Compton Telescope, a novel gamma-ray telescope designed for balloon-borne astrophysical observations, we have calibrated, the 3D positioning capabilities of a prototype 2mm pitch cross-strip Ge detector. To accurately position in the third dimension (depth) we use the relative timing difference in charge collection on the anode and cathode, a sensitive measure of depth in the detector. In order to calibrate the depth determination in terms of the collection time difference, we have developed a statistical calibration technique which involves illuminating opposite sides of the detector with photons of known energy and requiring self-consistency of the measured mean free path of the photons on both sides. Requiring this to occur simultaneously for several different photon energies ensures that there will be no energy dependence of the calibration (within our sensitivity range). We can then check for consistency with the known mean free paths in germanium for each photon energy, as well as with our detailed simulations of the detector performance. We present the result of our prototype detector calibration as well as demonstrate the excellent agreement between these calibrations and our simulations.

Use of `relative-phase' analysis to assess correlation between neuronal spike trains

We propose a new method of studying the correlation between neuronal spike trains. This technique is based on the analysis of relative phase between two point processes. Relative phase here is defined as the relative timing difference between two spike trains normalized by the associated interspike interval of one cell. This phase measurement is intended to reveal the relative timing relationship between spike trains at different firing rates. We apply this method to a numerical example and an example from two cerebellar neuronal spike trains of a behaving rat. The results are compared with classical cross-correlation analysis. We show that the technique can avoid some of the limitations of cross-correlation methods, reveal certain statistical dependencies that cannot be shown by cross correlation, and provide information as to the direction of influence between two spike trains.

The Neupert effect and new RHESSI measures of thetotal energy in electrons accelerated in solar flares

Abstract It is believed that a large fraction of the total energy released in a solar flare goes initially into acceleratedelectrons. These electrons generate the observed hard X-ray bremsstrahlung as they lose most of their energy by coulomb collisions in the lower corona and chromosphere. Results from the Solar Maximum Mission showed that there may be even more energy in accelerated electrons with energies above 25 keV than in the soft X-ray emitting thermal plasma. If this is the case, it is difficult to understand why the Neupert Effect — the empirical result that for many flares the time integral of the hard X-ray emission closely matches the temporal variation of the soft X-ray emission — is not more clearly observed in many flares. From recent studies, it appears that the fraction of the released energy going into accelerated electrons is lower, on average, for smaller flares than for larger flares. Also, from relative timing differences, about 25% of all flares are inconsistent with the Neupert Effect. The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is uniquely capable of investigating the Neupert Effec since it covers soft X-rays down to 3 keV (when both attenuators are out of the field of view) and hard X-rays with keV energy resolution, arcsecond-class angular resolution, and sub-second time resolution. When combined with the anticipated observations from the Soft X-ray Imager on the next GOES satellite, these observations will provide us with the ability to track the Neupert Effect in space and time and learn more about the relation between plasma heating and particle acceleration. The early results from RHESSI show that the electron spectrum extends down to as low as 10 keV in many flares, thus increasing the total energy estimates of the accelerated electrons by an order of magnitude or more compared with the SMM values. This combined with the possible effects of filling factors smaller than unity for the soft X-ray plasma suggest that there is significantly more energy in nonthermal electrons than in the soft X-ray emitting plasma in many flares.

Derivation of seismic cone interval velocities utilizing forward modeling and the downhill simplex method

The seismic cone penetration test (SCPT) has proven to be a very valuable geotechnical tool in facilitating the determination of low strain (<10–4%) in situ compression (P) and shear (S) wave velocities. The P- and S-wave velocities are directly related to the soil elastic constants of Poisson's ratio, shear modulus, bulk modulus, and Young's modulus. The accurate determination of P- and S-wave velocities from the recorded seismic cone time series is of paramount importance to the evaluation of reliable elastic constants. Furthermore, since the shear and compression wave velocities are squared in deriving the elastic constants, small variations in the estimated velocities can cause appreciable errors. The standard techniques implemented in deriving SCPT interval velocities rely upon obtaining reference P- and S-wave arrival times as the probe is advanced into the soil profile. By assuming a straight ray travel path from the source to the SCPT seismic receiver and calculating the relative reference arrival time differences, interval SCPT velocities are obtained. The forward modeling – downhill simplex method (FMDSM) outlined in this paper offers distinct advantages over conventional SCPT velocity profile estimation methods. Some of these advantages consist of the allowance of ray path refraction, greater sophistication in interval velocity determination, incorporation of measurement weights, and meaningful interval velocity accuracy estimators.Key words: seismic cone penetration testing (SCPT), downhill simplex method (DSM), forward modeling, Fermat's principle, weighted least squares (l2 norm), cost function.

Optical clock recovery using SOA for relative timing extraction between counterpropagating short picosecond pulses

A technique that determines the relative arrival timing difference between two counterpropagating picosecond pulses in a nonlinear waveguide is presented. Optical clock recovery experiment constructed around a semiconductor optical amplifier demonstrates a recovered clock with less than 100 fs of jitter. The bit-error-rate measurement at 10 GHz, using 2/sup 31/-1 long pseudorandom bit sequence data, revealed error free operation.