Trace Segments Research Articles

Association of the Iγ and Iδ Charge Movement with Calcium Release in Frog Skeletal Muscle

Charge movement and calcium transient were measured simultaneously in stretched frog cut twitch fibers under voltage clamp, with the internal solution containing 20mM EGTA plus added calcium and antipyrylazo III. When the nominal free [Ca2+]i was 10nM, the shape of the broad Iγ hump in the ON segments of charge movement traces remained invariant when the calcium release rate was greatly diminished. When the nominal free [Ca2+]i was 50nM, which was close to the physiological level, the Iγ humps were accelerated and a slow calcium-dependent Iδ component (or state) was generated. The peak of ON Iδ synchronized perfectly with the peak of the calcium release rate whereas the slow decay of ON Iδ followed the same time course as the decay of calcium release rate. Suppression of calcium release by TMB-8 reduced the amount of Qδ concomitantly but not completely, and the effects were partially reversible. The same simultaneous suppression effects were achieved by depleting the sarcoplasmic reticulum calcium store with repetitive stimulation. The results suggest that the mobility of Qδ needs to be primed by a physiological level of resting myoplasmic Ca2+. Once the priming is completed, more Iδ is mobilized by the released Ca2+ during depolarization.

Nasopharyngeal carcinoma tumor volume measurement..

Tumor volume was measured in 69 patients with nasopharyngeal carcinoma. On transverse nonenhanced T1-weighted and gadolinium-enhanced T1-weighted magnetic resonance (MR) images, segmentation was performed by means of seed growing and knowledge-based fuzzy clustering methods. Data were compared with those collected with the manual tracing method and analyzed for interoperator variance and interobserver reliability. There was no significant difference between the volumes determined with manual tracing or semiautomated segmentation (P >.05). On the volume level, Pearson correction coefficients were close for both the manual tracing and semiautomated methods. Significant differences in interoperator variance existed between the two methods on the pixel level (P <.05). Compared with manual tracing, the semiautomated method helped reduce interoperator variance and obtain higher interobserver reliability. Findings in the current study validate the use of semiautomated volume measurement methods for nasopharyngeal carcinoma.

Tongue carcinoma: tumor volume measurement

Purpose To validate the semiautomated methods of tongue carcinoma tumor volume measurement by comparing the conventional manual trace method with 2 semiautomated computer methods: seed growing and region deformation. Materials and methods The study population consisted of 16 patients with histology-proven tongue carcinoma. Two head-and-neck radiologists independently measured the tumor volume demonstrated on pretreatment T2-weighted magnetic resonance data sets. The tumor volumes were measured using manual tracing and semiautomated seed growing and region deformation algorithm. Data were recorded for analysis of interoperator variance and interobserver reliability at volume and pixel levels. Results There was no significant difference between the manually traced volume and semiautomated segmentation volumes for both operators. No significant difference was found in interobserver variance among the 3 methods at volume level. However, there was significant difference between manual tracing and semiautomated segmentation methods in interobserver reliability at pixel level. Conclusion The semiautomated methods could achieve satisfactory segmentation results. They could also reduce interoperator variance and obtain a higher interobserver reliability. This study validates the use of semiautomated volume measurement methods for tongue carcinoma.

Geometry and structure of northern surface ruptures of the 1999 Mw=7.6 Chi-Chi Taiwan earthquake: influence from inherited fold belt structures

Surface ruptures associated with the 1999 Mw=7.6 Chi-Chi earthquake in central western Taiwan have been characterised by mapping along the northern fault-segment. The earthquake occurred on the reactivated Chelungpu fault in the frontal portion of the thin-skinned Taiwan fold-and-thrust belt. The N–S trending Chelungpu fault is a 90-km-long major west-verging thrust, which principally slips within, and parallel to, bedding of the Pliocene Chinshui Shale. In the northern segment of the earthquake fault trace, that we name the Shihkang–Shangchi fault zone, the surface ruptures turn to an E–W strike and produce a series of thrust-and-backthrust pop-ups, about 15km long, forming several discontinuous subsegments distributed within a broad regional Pliocene syncline.The northern fault segments activated during the Chi-Chi earthquake, in the area where the displacement is largest, not only display anomalous trends and a variety of mechanisms, but also raise a major problem of structural inheritance. Detailed field investigation and kinematic analysis indicate that the surface ruptures in the Shihkang–Shangchi fault zone are the result of dip-slip thrusting, occasionally with a minor strike-slip component. The surface ruptures emerge at the surface from bedding-parallel thrusts on both limbs of the regional south-plunging syncline. In the middle part of the syncline, bedding-parallel thrusts are connected by thrusts that cross-cut beds. The surface ruptures also reactivate a NE–SW trending anticline (Diaoshenshan), with west-vergent thrust on the backlimb and east-vergent backthrust on the forelimb. This anticline is undergoing uplift by breaking through the regional N–S trending syncline.Combining GPS measurements, seismological data, and geological analyses, we propose a kinematic model with a 3-D fault surface for the 1999 earthquake in the area of the northern termination. We highlight the influence of both the local and regional structures (bedding parallel slip, pre-existing faults and folds) on the development of the earthquake rupture, and hence the role of the structural inheritance. We conclude that the south-plunging regional Pliocene syncline in fact acts as a slip/strain guide for the northern termination of the Chelungpu thrust. The Pliocene Chinshui Shale, as a major source of weakness within the syncline, has strongly influenced the pattern of slip surface during the 1999 earthquake rupture. We interpret the large vertical displacement along the northern segment as the fault rupture occurring over a surface whose radius of curvature tightens toward the north around the core of the syncline.

Uncoupling of contingent negative variation and alpha band event-related desynchronization in a go/no-go task

Objectives: To examine how the differences in the sequences of brain activation during the go/no-go delayed response choice reaction time (RT) task are reflected into two concurrent methods of measuring brain electrical activity, the alpha band event-related desynchronization (αERD) and the contingent negative variation (CNV).Methods: αERD and CNV were calculated using appropriate techniques from the same samples of electroencephalographic activity recorded during performance of a cued choice go/no-go delayed response RT task (i.e. S1 (go/no-go)–S2 paradigm) in 8 healthy subjects.Results: All segments of the CNV traces were different in the go and the no-go conditions. The go CNV traces displayed a typical pattern of slow rising negativity reflecting the build-up of attentional resources necessary for adequate performance of the task. On the other hand, the no-go traces remained close to zero reflecting the ‘withdrawal’ of further preparation after evaluation of S1. During the same period, both go and no-go ERD traces showed a gradual decrease in alpha band power (desynchronization) that was evident until shortly before the presentation of S2. It was only in the 500 ms before S2 presentation that there was any indication that the go and no-go ERD traces were different, but this did not reach statistical significance.Conclusions: Our data show that the pattern of the go/no-go difference in αERD traces does not correspond to the pattern that can be seen in the CNV traces. This suggests that there is no direct coupling of CNV and αERD, most probably because they measure different aspects of cortical electrical activity. In addition, the extent of the no-go αERD reveals that refraining from performance of a pre-programmed movement is by no means a passive/inactive process.

Improving seismic chimney detection using directional attributes

The chimney cube is a seismic body detection technique to facilitate the interpretation of seismic chimneys. The method uses multi-attributes and a supervised neural network to produce a chimney cube, i.e. a three-dimensional (3D) volume of the chimney probability. In the original method, single and multi-trace attributes are extracted in three vertically aligned windows. Within each window the energy and several trace-to-trace similarities are computed. Similarities are computed without correcting for structural dip. Here we discuss improvements made to the original algorithm by taking local dip and azimuth information into account. The similarity attributes are now calculated by following the local direction (dip and azimuth) from trace to trace. A technique we call “phase-locking” fine-tunes the calculated times at which trace segments are extracted for similarity calculations. The new network with these similarities and a new attribute called dip-variance yields a lower misclassification and a significantly higher resolution chimney cube as compared to the original algorithm.

A survey of new research directions in microprocessors

Current microprocessors utilise the instruction-level parallelism by a deep processor pipeline and the superscalar instruction issue technique. VLSI technology offers several solutions for aggressive exploitation of the instruction-level parallelism in future generations of microprocessors. Technological advances will replace the gate delay by on-chip wire delay as the main obstacle to increase the chip complexity and cycle rate. The implication for the microarchitecture is that functionally partitioned designs with strict nearest neighbour connections must be developed. Among the major problems facing the microprocessor designers is the application of even higher degree of speculation in combination with functional partitioning of the processor, which prepares the way for exceeding the classical dataflow limit imposed by data dependences. In this paper we survey the current approaches to solving this problem, in particular we analyse several new research directions whose solutions are based on the complex uniprocessor architecture. A uniprocessor chip features a very aggressive superscalar design combined with a trace cache and superspeculative techniques. Superspeculative techniques exceed the classical dataflow limit where even with unlimited machine resources a program cannot execute any faster than the execution of the longest dependence chain introduced by the program's data dependences. Superspeculative processors also speculate about control dependences. The trace cache stores the dynamic instruction traces contiguously and fetches instructions from the trace cache rather than from the instruction cache. Since a dynamic trace of instructions may contain multiple taken branches, there is no need to fetch from multiple targets, as would be necessary when predicting multiple branches and fetching 16 or 32 instructions from the instruction cache. Multiscalar and trace processors define several processing cores that speculatively execute different parts of a sequential program in parallel. Multiscalar processors use a compiler to partition the program segments, whereas a trace processor uses a trace cache to generate dynamically trace segments for the processing cores. A datascalar processor runs the same sequential program redundantly on several processing elements where each processing element has different data set. This paper discusses and compares the performance potential of these complex uniprocessors.

Tracing echo segment selecting method for strain reconstruction

There are numbers of error sources in elastography construction. In its basic procedure of tissue segment displacement estimation, error will be generated due to the echo waveform distortion. In this paper the necessity of a tracing segment selection is proposed and demonstrated with simulation data. To separate the tracing segments with less distortion from those segments with more distortion, the names central and edge segment are introduced. Following the idea of reducing the strain reconstruction error by discarding the edge segments and only using the central segment in the estimation of displacement, four tracing segment selection methods are established, namely the phase irregularity rejection method, the echo envelop peak centering method, the echo envelop threshold method, and the echo correlation envelop selection method. Simulation results indicate that these methods are effective in reducing the strain reconstruction error. Among the first three methods, the echo envelop peak centering method is more efficient in reducing the error but with a trade-off of losing the resolution.

The geometry of polygonal fault systems in Tertiary mudrocks of the North Sea

Polygonal networks of extensional faults have recently been identified deforming large volumes of Tertiary mudrocks in the North Sea. The main distinctive feature of this fault system is a near equal distribution of fault strike orientations and polygonal organisation of the fault trace segments in plan view. Detailed fault mapping using three-dimensional seismic reflection datasets from the central North Sea show that the complex three-dimensional geometries are primarily a function of intersections between fault surfaces oriented in all directions in space. Within stratigraphic units or layers the deformation is distributed as opposed to the clustered deformation of more co-linear tectonic fault arrays where the strain is concentrated into zones or bands at a variety of scales. End member map patterns with curved, rectilinear or irregular polygonal geometries are identified that encompass the variability observed on over 30 fault maps made at different stratigraphic levels within the three-dimesional seismic datasets. Four main classes of intersections between fault segments are defined providing a descriptive geometric framework for polygonal fault systems. The geometry of the intersection types and their geometrical stability in three-dimensions is discussed with reference to examples from the seismic datasets. Fault shapes are irregular and, in detail, shape is largely a function of intersection relationships with neighbouring faults. Faults can be planar or listric, and can have triangular shapes that may taper upwards or downwards. They frequently exhibit complex irregular upper tips. Completely isolated non-connected faults are very rare within the three-dimensional datasets studied.

Improving trace cache effectiveness with branch promotion and trace packing

The increasing widths of superscalar processors are placing greater demands upon the fetch mechanism. The trace cache meets these demands by placing logically contiguous instructions in physically contiguous storage. As a result, the trace cache delivers instructions at a high rate by supplying multiple fetch blocks each cycle.In this paper, we examine two techniques to improve the number of instructions delivered each cycle by the trace cache. The first technique, branch promotion, dynamically converts strongly biased branches into branches with static predictions. Because these promoted branches require no dynamic prediction, the branch predictor suffers less from the negative effects of interference.Branch promotion unlocks the potential of the second technique: trace packing. With trace packing, trace segments are packed with as many instructions as will fit, without regard to naturally occurring fetch block boundaries. With both techniques, the effective fetch rate of the trace cache jumps up 17% over a trace cache which implements neither.On a machine where the execution engine has a very aggressive memory disambiguator, the performance of a machine using branch promotion and trace packing is on average 11% higher than a machine using neither technique.

Application of back-propagation neural networks to identification of seismic arrival types

A back-propagation neural network (BPNN) approach is developed to identify P- and S-arrivals from three-component recordings of local earthquake data. The BPNN is trained by selecting trace segments of P- and S-waves and noise bursts converted into an attribute space based on the degree of polarization (DOP). After training, the network can automatically identify the type of arrival on earthquake recordings. Compared with manual analysis, a BPNN trained with nine groups of DOP segments can correctly identify 82.3% of the P-arrivals and 62.6% of the S-arrivals from one seismic station, and when trained with five groups from a training dataset selected from another seismic station, it can correctly identify 76.6% of the P-arrivals and 60.5% of S-arrivals. This approach is adaptive and needs only the onset time of arrivals as input, although its performance cannot be improved by simply adding more training datasets due to the complexity of DOP patterns. Our experience suggests that other information or another network may be necessary to improve its performance.

Automatic extraction and measurement of leukocyte motion in microvessels using spatiotemporal image analysis

This paper describes a computer vision system for the automatic extraction and velocity measurement of moving leukocytes that adhere to microvessel walls from a sequence of images. The motion of these leukocytes can be visualized as motion along the wall contours. We use the constraint that the leukocytes move along the vessel wall contours to generate a spatiotemporal image, and the leukocyte motion is then extracted using the methods of spatiotemporal image analysis. The generated spatiotemporal image is processed by a special-purpose orientation-selective filter and a subsequent grouping process newly developed for this application. The orientation-selective filter is designed by considering the particular properties of the spatiotemporal image in this application in order to enhance only the traces of leukocytes. In the subsequent grouping process, leukocyte trace segments are selected and grouped among all the segments obtained by simple thresholding and skeletonizing operations. We show experimentally that the proposed method can stably extract leukocyte motion.

Characterizing seismic time series using the discrete wavelet transform

The discrete wavelet transform (DWT) has potential as a tool for supplying discriminatory attributes with which to characterize or cluster groups of seismic traces in reservoir studies. The wavelet transform has the great advantage over the Fourier transform in being able to better localize changes. The multiscale nature and structure of the DWT leads to a method of display which highlights this and allows comparison of changes in the transform with changing data. Many different sorts of wavelet exist and it is found that the quality of reconstruction of a seismic trace wavelet exist and it is found that the quality of reconstruction of a seismic trace segment, using some of the coefficients, is dependent on the choice of wavelet, which leads us to consider choosing a wavelet under a best reconstruction criterion. Location shifts, time zero uncertainties, are also shown to affect the transform, as do truncations, resampling, etc. Using real data, examples of utilizing the DWT coefficients as attributes for whole trace segments or fractional trace segments are given. Provided the DWT is applied consistently, for example with a fixed wavelet, and non-truncated data, the transform produces useful results. Care must be exercised if it is applied tomore » data of different lengths. However, as the algorithm is refined and improved in the future, the DWT should prove increasingly useful.« less

Growth of vertically segmented normal faults

The geometry and evolution of vertically segmented normal faults, with dip separations of < ca 11.5 m have been studied in a coastal outcrop of finely bedded Cretaceous chalk at Flamborough Head, U.K. Fault trace segments are separated by both contractional and extensional offsets which have step, overlap or bend geometries. The location of fault trace offsets is strongly controlled by lithology occurring at either thin ( ca 1 mm-8 cm) and mechanically weak marl layers or partings between chalk units. Fault segmentation occurred during either fault nucleation within, or propagation through, the strongly anisotropic lithological sequence. An inverse relationship between fault displacement and number of offsets per length of fault trace reflects the progressive destruction of offsets during fault growth. The preservation of fault offsets is therefore dependent on offset width and fault displacement. Fault rock, comprising gouge and chalk breccia, may vary in thickness by 1.5–2.0 orders of magnitude on individual fault traces. Strongly heterogeneous fault rock distributions are most common on small faults (< 10 cm displacement) and are produced mainly by destruction of fault offsets. Shearing of fault rock with increasing displacement gives rise to a more homogeneous fault rock distribution on large faults at the outcrop scale.

Feedback neural networks for ARTIST ionogram processing

Modern pattern recognition techniques are applied to achieve high quality automatic processing of Digisonde ionograms. An artificial neural network (ANN) was found to be a promising technique for ionospheric echo tracing. A modified rotor model was tested to construct the Hopfield ANN with the mean field theory updating scheme. Tests of the models against various ionospheric data showed that the modified rotor model gives good results where conventional tracing techniques have difficulties. Use of the ANN made it possible to implement a robust scheme of trace interpretation that considers local trace inclination angles available after ANN completes tracing. The interpretation scheme features a new algorithm for ƒ0F1 identification that estimates an α angle for the trace segments in the vicinity of the critical frequency ƒ0F1. First results from off‐line tests suggest the potential of implementing new operational autoscaling software in the worldwide Digisonde network.

Tracer of complex movement by using five optical line detectors and fifth-order cross-correlation analysis

A new method to detect the trace of complex movement of vehicle by using five optical line detectors and fifth-order cross-correlation analysis is proposed. In this method, the curvature and center coordinates of trace segment can be estimated simultaneously together with the velocity of the vehicle's motion. Hence the trace of the vehicle in a fixed measuring time interval can be detected as a circular are and the whole trace is reconstructed as the connection of these arcs. To confirm the usefulness of the proposed method, an actual measurement system has been constructed and experiments using the sham road of which movement was controlled have been carried out. The details of the principle, system construction and the results are shown.

Inferred depth of creep on the Hayward Fault, central California

A relation between creep rate at the surface trace of a fault, the depth to the bottom of the creeping zone, and the rate of stress accumulation on the fault is derived from Weertman's 1964 friction model of slip on a fault. A 5 ± 1 km depth for the creeping zone on the Hayward fault is estimated from the measured creep rate (5 mm/yr) at the fault trace and the rate of stress increase on the upper segment of the fault trace inferred from geodetic measurements across the San Francisco Bay area. Although fault creep partially accommodates the secular slip rate on the Hayward fault, a slip deficit is accumulating equivalent to a magnitude 6.6 earthquake on each 40 km segment of the fault each century. Thus, the current behavior of the fault is consistent with its seismic history, which includes two moderate earthquakes in the mid‐1800's.

Image processing for the study of brain structure and function: problems and programs.

Fundamental problems in the analysis of functional and structural imaging data include data transport, boundary identification (including manual tracing, edge detection, and tissue segmentation), volume estimation, three-dimensional reconstruction and display, surface and volume rendering, shape analysis, and image overlay. These problems require that research investigators have access to suitable methods of image analysis, implemented on a set of software programs, in order to conduct neuroimaging research. The authors describe a group of software programs designed to provide a comprehensive solution for these problems.

Factors affecting the appearance of the hump charge movement component in frog cut twitch fibers.

Charge movement was measured in frog cut twitch fibers with the double Vaseline gap technique. Five manipulations listed below were applied to investigate their effects on the hump component (I gamma) in the ON segments of TEST minus CONTROL current traces. When external Cl-1 was replaced by MeSO3- to eliminate Cl current, I gamma peaked earlier due to a few millivolts shift of the voltage dependence of I gamma kinetics in the negative direction. The Q-V plots in the TEA.Cl and TEA.MeSO3 solutions were well fitted by a sum of two Boltzmann distribution functions. The more steeply voltage-dependent component (Q gamma) had a V approximately 6 mV more negative in the TEA.MeSO3 solution than in the TEA.Cl solution. These voltage shifts were partially reversible. When creatine phosphate in the end pool solution was removed, the I gamma hump disappeared slowly over the course of 20-30 min, partly due to a suppression of Q gamma. The hump reappeared when creatine phosphate was restored. When 0.2-1.0 mM Cd2+ was added to the center pool solution to block inward Ca current, the I gamma hump became less prominent due to a prolongation in the time course of I gamma but not to a suppression of Q gamma. When the holding potential was changed from -90 to -120 mV, the amplitude of I beta was increased, thereby obscuring the I gamma hump. Finally, when a cut fiber was stimulated repetitively, I gamma lost its hump appearance because its time course was prolonged. In an extreme case, a 5-min resting interval was insufficient for a complete recovery of the waveform. In general, a stimulation rate of once per minute had a negligible effect on the shape of I gamma. Of the five manipulations, MeSO3- has the least perturbation on the appearance of I gamma and is potentially a better substitute for Cl- than SO2-(4) in eliminating Cl current if the appearance of the I gamma hump is to be preserved.

Evaluation of P- and S-wave sources for shallow seismic reflection

The theoretical attractiveness of utilising both P- and S-reflection information is offset in the shallow environment by the practical difficulty of isolating high resolution reflections from other non-reflection energy. Source design is a critical component in a range of mandatory acquisition and processing optimisations. Four near-surface P-wave sources (high explosive, shotgun, weight drop, and hammer) have been evaluated in terms of their suitability for shallow reflection at a test site in the Ipswich Basin, southeast Queensland. Cross power spectral analyses of trace segments in the reflection window provide an estimate of the ‘coherent bandwidth’ of the different sources. Although the high explosive has superior signal levels, consideration of spectral symmetry, autocorrelation shape, and logistic aspects indicates that the shotgun source is a viable alternative. A pneumatic powered S-wave generator has been constructed and tested. Integrated spectral energies have been used to monitor piston velocity limitations and hence define optimum operating parameters. The pneumatic source is more controllable and of higher energy than a sledgehammer-powered equivalent.