Journal articles: 'SPIKE-distance'

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Kreuz, Thomas. "SPIKE-distance." Scholarpedia 7, no. 12 (2012): 30652. http://dx.doi.org/10.4249/scholarpedia.30652.

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Rossum, M. C. W. van. "A Novel Spike Distance." Neural Computation 13, no. 4 (April 1, 2001): 751–63. http://dx.doi.org/10.1162/089976601300014321.

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The discrimination between two spike trains is a fundamental problem for both experimentalists and the nervous system itself. We introduce a measure for the distance between two spike trains. The distance has a time constant as a parameter. Depending on this parameter, the distance interpolates between a coincidence detector and a rate difference counter. The dependence of the distance on noise is studied with an integrate-andfire model. For an intermediate range of the time constants, the distance depends linearly on the noise. This property can be used to determine the intrinsic noise of a neuron.

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Fu, Q. G., D. Flament, J. D. Coltz, and T. J. Ebner. "Relationship of Cerebellar Purkinje Cell Simple Spike Discharge to Movement Kinematics in the Monkey." Journal of Neurophysiology 78, no. 1 (July 1, 1997): 478–91. http://dx.doi.org/10.1152/jn.1997.78.1.478.

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Fu, Q.-G., D. Flament, J. D. Coltz, and T. J. Ebner. Relationship of cerebellar Purkinje cell simple spike discharge to movement kinematics in the monkey. J. Neurophysiol. 78: 478–491, 1997. The simple spike discharge of 231 cerebellar Purkinje cells in ipsilateral lobules V and VI was recorded in three monkeys trained to perform a visually guided reaching task requiring movements of different directions and distances. The discharge of 179 cells was significantly modulated during movement to one or more targets. Mean simple spike rate was fitted to a cosine function for direction tuning, a simple linear function for distance modulation, and a multiple linear regression model that included terms for direction, distance, and target position. On the basis of the fit to the direction and distance models, there were more distance-related than direction-related Purkinje cells. The simple spike discharge of most direction-related cells modulated at only one target distance. The preferred directions for the simple spike tuning were not uniformly distributed across the workspace. The discharge of most distance-related cells modulated along only one movement direction. On the basis of the multiple linear regression model, simple spike discharge was also correlated with target position, in addition to direction and distance. Approximately half of the Purkinje cells had simple spike activity associated with only a single parameter, and only a small fraction of the cells with all three. The multiple regression model was extended to evaluate the correlations as a function of time. Considerable overlap occurred in the timing of the simple spike correlations with the parameters. The latency for correlation with movement direction occurred mainly in a 500-ms interval centered on movement onset. The correlations with target position also occurred around movement onset, in the range of −200–500 ms. Distance correlations were more variable, with onset latencies from −500 to 1,000 ms. These results demonstrate that the simple spike discharge of cerebellar Purkinje cells is correlated with movement direction, distance, and target position. Comparing these results to motor cortical discharge shows that the correlations with these parameters were weaker in Purkinje cell simple spike discharge, and that, for the majority of Purkinje cells, the simple spike discharge was significantly related to only a single movement parameter. Other differences between simple spike responses and those of motor cortical cells include the nonuniform distribution of preferred directions and the extensive overlap in the timing of the correlations. These differences suggest that Purkinje cells process, encode, and use kinematic information differently than motor cortical neurons.

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Kreuz, Thomas, Daniel Chicharro, Conor Houghton, Ralph G. Andrzejak, and Florian Mormann. "Monitoring spike train synchrony." Journal of Neurophysiology 109, no. 5 (March 1, 2013): 1457–72. http://dx.doi.org/10.1152/jn.00873.2012.

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Recently, the SPIKE-distance has been proposed as a parameter-free and timescale-independent measure of spike train synchrony. This measure is time resolved since it relies on instantaneous estimates of spike train dissimilarity. However, its original definition led to spuriously high instantaneous values for eventlike firing patterns. Here we present a substantial improvement of this measure that eliminates this shortcoming. The reliability gained allows us to track changes in instantaneous clustering, i.e., time-localized patterns of (dis)similarity among multiple spike trains. Additional new features include selective and triggered temporal averaging as well as the instantaneous comparison of spike train groups. In a second step, a causal SPIKE-distance is defined such that the instantaneous values of dissimilarity rely on past information only so that time-resolved spike train synchrony can be estimated in real time. We demonstrate that these methods are capable of extracting valuable information from field data by monitoring the synchrony between neuronal spike trains during an epileptic seizure. Finally, the applicability of both the regular and the real-time SPIKE-distance to continuous data is illustrated on model electroencephalographic (EEG) recordings.

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Rusu, Cătălin V., and Răzvan V. Florian. "A New Class of Metrics for Spike Trains." Neural Computation 26, no. 2 (February 2014): 306–48. http://dx.doi.org/10.1162/neco_a_00545.

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The distance between a pair of spike trains, quantifying the differences between them, can be measured using various metrics. Here we introduce a new class of spike train metrics, inspired by the Pompeiu-Hausdorff distance, and compare them with existing metrics. Some of our new metrics (the modulus-metric and the max-metric) have characteristics that are qualitatively different from those of classical metrics like the van Rossum distance or the Victor and Purpura distance. The modulus-metric and the max-metric are particularly suitable for measuring distances between spike trains where information is encoded in bursts, but the number and the timing of spikes inside a burst do not carry information. The modulus-metric does not depend on any parameters and can be computed using a fast algorithm whose time depends linearly on the number of spikes in the two spike trains. We also introduce localized versions of the new metrics, which could have the biologically relevant interpretation of measuring the differences between spike trains as they are perceived at a particular moment in time by a neuron receiving these spike trains.

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Lou, Yanhong, Liang Chen, Qingguo Xu, and Xunzhong Zhang. "Genotypic Variation of Morphological Traits in Tall Fescue (Festuca arundinacea Schreb.) Accessions." HortScience 50, no. 4 (April 2015): 512–16. http://dx.doi.org/10.21273/hortsci.50.4.512.

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Tall fescue is an important cool-season grass widely used for forage and turf, and its genotypic variation for morphological traits has not been well documented. One hundred and fifteen tall fescue accessions, including 25 commercial cultivars, were divided into five groups based on their origination. The morphological traits, including plant height, spike length, pulvinus distance, spikelet count, branch count per spike, spike count per plant, and spike weight in different accessions were determined under field conditions in 2013 and 2014. There was significant genotypic variation in morphological traits among the 115 tall fescue accessions. Wild accessions exhibited a greater variation in the morphological traits than commercial cultivars. Close correlations were found among plant height, spike length, pulvinus distance, and spikelet count. The results of this suggest plant height, spike length, pulvinus distance, and spikelet count could be used as key morphological traits for evaluating all fescue germplasm effectively.

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Kreuz, Thomas, Mario Mulansky, and Nebojsa Bozanic. "SPIKY: a graphical user interface for monitoring spike train synchrony." Journal of Neurophysiology 113, no. 9 (May 2015): 3432–45. http://dx.doi.org/10.1152/jn.00848.2014.

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Techniques for recording large-scale neuronal spiking activity are developing very fast. This leads to an increasing demand for algorithms capable of analyzing large amounts of experimental spike train data. One of the most crucial and demanding tasks is the identification of similarity patterns with a very high temporal resolution and across different spatial scales. To address this task, in recent years three time-resolved measures of spike train synchrony have been proposed, the ISI-distance, the SPIKE-distance, and event synchronization. The Matlab source codes for calculating and visualizing these measures have been made publicly available. However, due to the many different possible representations of the results the use of these codes is rather complicated and their application requires some basic knowledge of Matlab. Thus it became desirable to provide a more user-friendly and interactive interface. Here we address this need and present SPIKY, a graphical user interface that facilitates the application of time-resolved measures of spike train synchrony to both simulated and real data. SPIKY includes implementations of the ISI-distance, the SPIKE-distance, and the SPIKE-synchronization (an improved and simplified extension of event synchronization) that have been optimized with respect to computation speed and memory demand. It also comprises a spike train generator and an event detector that makes it capable of analyzing continuous data. Finally, the SPIKY package includes additional complementary programs aimed at the analysis of large numbers of datasets and the estimation of significance levels.

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Christen, Markus, Adam Kohn, Thomas Ott, and Ruedi Stoop. "Measuring spike pattern reliability with the Lempel–Ziv-distance." Journal of Neuroscience Methods 156, no. 1-2 (September 2006): 342–50. http://dx.doi.org/10.1016/j.jneumeth.2006.02.023.

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Zhu, Jinjie, and Xianbin Liu. "Measuring spike timing distance in the Hindmarsh–Rose neurons." Cognitive Neurodynamics 12, no. 2 (December 27, 2017): 225–34. http://dx.doi.org/10.1007/s11571-017-9466-9.

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Kang, Kukjin, and Shun-ichi Amari. "Discrimination with Spike Times and ISI Distributions." Neural Computation 20, no. 6 (June 2008): 1411–26. http://dx.doi.org/10.1162/neco.2007.07-07-561.

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We study the discrimination capability of spike time sequences using the Chernoff distance as a metric. We assume that spike sequences are generated by renewal processes and study how the Chernoff distance depends on the shape of interspike interval (ISI) distribution. First, we consider a lower bound to the Chernoff distance because it has a simple closed form. Then we consider specific models of ISI distributions such as the gamma, inverse gaussian (IG), exponential with refractory period (ER), and that of the leaky integrate-and-fire (LIF) neuron. We found that the discrimination capability of spike times strongly depends on high-order moments of ISI and that it is higher when the spike time sequence has a larger skewness and a smaller kurtosis. High variability in terms of coefficient of variation (CV) does not necessarily mean that the spike times have less discrimination capability. Spike sequences generated by the gamma distribution have the minimum discrimination capability for a given mean and variance of ISI. We used series expansions to calculate the mean and variance of ISIs for LIF neurons as a function of the mean input level and the input noise variance. Spike sequences from an LIF neuron are more capable of discrimination than those of IG and gamma distributions when the stationary voltage level is close to the neuron's threshold value of the neuron.

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Ciba, Manuel, Robert Bestel, Christoph Nick, Guilherme Ferraz de Arruda, Thomas Peron, Comin César Henrique, Luciano da Fontoura Costa, Francisco Aparecido Rodrigues, and Christiane Thielemann. "Comparison of Different Spike Train Synchrony Measures Regarding Their Robustness to Erroneous Data From Bicuculline-Induced Epileptiform Activity." Neural Computation 32, no. 5 (May 2020): 887–911. http://dx.doi.org/10.1162/neco_a_01277.

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As synchronized activity is associated with basic brain functions and pathological states, spike train synchrony has become an important measure to analyze experimental neuronal data. Many measures of spike train synchrony have been proposed, but there is no gold standard allowing for comparison of results from different experiments. This work aims to provide guidance on which synchrony measure is best suited to quantify the effect of epileptiform-inducing substances (e.g., bicuculline, BIC) in in vitro neuronal spike train data. Spike train data from recordings are likely to suffer from erroneous spike detection, such as missed spikes (false negative) or noise (false positive). Therefore, different timescale-dependent (cross-correlation, mutual information, spike time tiling coefficient) and timescale-independent (Spike-contrast, phase synchronization (PS), A-SPIKE-synchronization, A-ISI-distance, ARI-SPIKE-distance) synchrony measures were compared in terms of their robustness to erroneous spike trains. For this purpose, erroneous spike trains were generated by randomly adding (false positive) or deleting (false negative) spikes (in silico manipulated data) from experimental data. In addition, experimental data were analyzed using different spike detection threshold factors in order to confirm the robustness of the synchrony measures. All experimental data were recorded from cortical neuronal networks on microelectrode array chips, which show epileptiform activity induced by the substance BIC. As a result of the in silico manipulated data, Spike-contrast was the only measure that was robust to false-negative as well as false-positive spikes. Analyzing the experimental data set revealed that all measures were able to capture the effect of BIC in a statistically significant way, with Spike-contrast showing the highest statistical significance even at low spike detection thresholds. In summary, we suggest using Spike-contrast to complement established synchrony measures because it is timescale independent and robust to erroneous spike trains.

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Moore, Michael J., Tadashi Nakano, Akihiro Enomoto, and Tatsuya Suda. "Measuring Distance From Single Spike Feedback Signals in Molecular Communication." IEEE Transactions on Signal Processing 60, no. 7 (July 2012): 3576–87. http://dx.doi.org/10.1109/tsp.2012.2193571.

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Tomas, P., and L. Sousa. "Statistical Analysis of a Spike Train Distance in Poisson Models." IEEE Signal Processing Letters 15 (2008): 357–60. http://dx.doi.org/10.1109/lsp.2008.919994.

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Eisenman, Lawrence N., Christine M. Emnett, Jayaram Mohan, Charles F. Zorumski, and Steven Mennerick. "Quantification of bursting and synchrony in cultured hippocampal neurons." Journal of Neurophysiology 114, no. 2 (August 2015): 1059–71. http://dx.doi.org/10.1152/jn.00079.2015.

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It is widely appreciated that neuronal networks exhibit patterns of bursting and synchrony that are not captured by simple measures such as average spike rate. These patterns can encode information or represent pathological behavior such as seizures. However, methods for quantifying bursting and synchrony are not agreed upon and can be confounded with spike rate measures. Previous validation has largely relied on in silico networks and single experimental conditions. How published measures of bursting and synchrony perform when applied to biological networks of varied average spike rate and subjected to varied experimental challenges is unclear. In multielectrode array recordings of network activity, we found that two mechanistically distinct drugs, cyclothiazide and bicuculline, produced equivalent increases in average spike rate but differed in bursting and synchrony. We applied several measures of bursting to the recordings (2 threshold interval methods and a surprise-based method) and found that a measure based on an average critical interval, adjusted for the array-wide spike rate, performed best in quantifying differential drug effects. To quantify synchrony, we compared a coefficient of variation-based measure, the recently proposed spike time tiling coefficient, the SPIKE-distance measure, and a global synchrony index. The spike time tiling coefficient, the SPIKE-distance measure, and the global synchrony index all captured a difference between drugs with the best performance exhibited by the global synchrony index. In summary, our exploration should aid other investigators by highlighting strengths and limitations of current methods.

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Więcław, Helena. "Morphological variability of the Carex oederi s. l. inflorescence." Biodiversity: Research and Conservation 21, no. 1 (January 1, 2011): 13–18. http://dx.doi.org/10.2478/v10119-011-0003-0.

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Morphological variability of theCarex oederis. l. inflorescenceThe most variable features describingCarex oederis. l. include: (i) the distance between two lower female spikes, (ii) the length of the peduncle of a lower female spike, (iii) the distance between two upper female spikes, (iv) the length of inflorescence and peduncle of a male spike. Most of observed stems had (3)4-5 female spikes, which were crowded around a sessile and short male spike. Specimens with fewer female spikes (2-3) were characterized generally by their loose positioning on a stem (occasionally a lower female spike was distant and had a peduncle) and the presence of usually longer male spikes on a peduncle. In conclusion,C. oederis. l. is highly variable morphologically. In the investigated materials, there are no apparent discontinuities. Further (planned) biometric research will be extended to the characteristics of the perygynium and vegetative features.

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Du, Ying, Rubin Wang, and Jingyi Qu. "Noise and Synchronization Analysis of the Cold-Receptor Neuronal Network Model." Discrete Dynamics in Nature and Society 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/173894.

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This paper analyzes the dynamics of the cold receptor neural network model. First, it examines noise effects on neuronal stimulus in the model. FromISIplots, it is shown that there are considerable differences between purely deterministic simulations and noisy ones. TheISI-distance is used to measure the noise effects on spike trains quantitatively. It is found that spike trains observed in neural models can be more strongly affected by noise for different temperatures in some aspects; meanwhile, spike train has greater variability with the noise intensity increasing. The synchronization of neuronal network with different connectivity patterns is also studied. It is shown that chaotic and high period patterns are more difficult to get complete synchronization than the situation in single spike and low period patterns. The neuronal network will exhibit various patterns of firing synchronization by varying some key parameters such as the coupling strength. Different types of firing synchronization are diagnosed by a correlation coefficient and theISI-distance method. The simulations show that the synchronization status of neurons is related to the network connectivity patterns.

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H. Berjis, Zaid, and Ahmed K. Al-sulaifanie. "Neural Spike Sorting And Classification." Journal Of Duhok University 23, no. 2 (December 9, 2020): 166–78. http://dx.doi.org/10.26682/sjuod.2020.23.2.18.

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Spike sorting is the process of separating the extracellular recording of the brain signal into one unit activity. There are a number of proposed algorithms for this purpose, but there is still no acceptable solution. In this paper a spike sorting method has been proposed based on the Euclidean distance of the most effective features of spikes represented by principle components (PCs) of the detected and aligned spikes. The assessments of the method, based on signal-to-noise ratio (SNR) representing background noise, showed that the method performed spike sorting to a high level of accuracy.

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Houghton, Conor, and Kamal Sen. "A New Multineuron Spike Train Metric." Neural Computation 20, no. 6 (June 2008): 1495–511. http://dx.doi.org/10.1162/neco.2007.10-06-350.

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The Victor-Purpura spike train metric has recently been extended to a family of multineuron metrics and used to analyze spike trains recorded simultaneously from pairs of proximate neurons. The metric is one of the two metrics commonly used for quantifying the distance between two spike trains; the other is the van Rossum metric. Here, we suggest an extension of the van Rossum metric to a multineuron metric. We believe this gives a metric that is both natural and easy to calculate. Both types of multineuron metric are applied to simulated data and are compared.

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Dubbs, Alexander J., Brad A. Seiler, and Marcelo O. Magnasco. "A Fast ℒp Spike Alignment Metric." Neural Computation 22, no. 11 (November 2010): 2785–808. http://dx.doi.org/10.1162/neco_a_00026.

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The metrization of the space of neural responses is an ongoing research program seeking to find natural ways to describe, in geometrical terms, the sets of possible activities in the brain. One component of this program is spike metrics—notions of distance between two spike trains recorded from a neuron. Alignment spike metrics work by identifying “equivalent” spikes in both trains. We present an alignment spike metric having [Formula: see text] underlying geometrical structure; the [Formula: see text] version is Euclidean and is suitable for further embedding in Euclidean spaces by multidimensional scaling methods or related procedures. We show how to implement a fast algorithm for the computation of this metric based on bipartite graph matching theory.

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Paiva, António R. C., Il Park, and José C. Príncipe. "A Reproducing Kernel Hilbert Space Framework for Spike Train Signal Processing." Neural Computation 21, no. 2 (February 2009): 424–49. http://dx.doi.org/10.1162/neco.2008.09-07-614.

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This letter presents a general framework based on reproducing kernel Hilbert spaces (RKHS) to mathematically describe and manipulate spike trains. The main idea is the definition of inner products to allow spike train signal processing from basic principles while incorporating their statistical description as point processes. Moreover, because many inner products can be formulated, a particular definition can be crafted to best fit an application. These ideas are illustrated by the definition of a number of spike train inner products. To further elicit the advantages of the RKHS framework, a family of these inner products, the cross-intensity (CI) kernels, is analyzed in detail. This inner product family encapsulates the statistical description from the conditional intensity functions of spike trains. The problem of their estimation is also addressed. The simplest of the spike train kernels in this family provide an interesting perspective to others' work, as will be demonstrated in terms of spike train distance measures. Finally, as an application example, the RKHS framework is used to derive a clustering algorithm for spike trains from simple principles.

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Wetmore, Daniel Z., and Stuart N. Baker. "Post-spike distance-to-threshold trajectories of neurones in monkey motor cortex." Journal of Physiology 555, no. 3 (March 9, 2004): 831–50. http://dx.doi.org/10.1113/jphysiol.2003.048918.

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DI MAIO, VITO, and FORTUNATO MARCIANO. "AUTOMATIC CLASSIFICATION OF NEURAL SPIKE ACTIVITY: AN APPLICATION OF MINIMUM DISTANCE CLASSIFIERS." Cybernetics and Systems 34, no. 3 (April 2003): 173–92. http://dx.doi.org/10.1080/01969720302839.

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Tang, Lilly, Mary Mantle, Paul Ferrari, Hagen Schiffbauer, Howard A. Rowley, Nicholas M. Barbaro, Mitchel S. Berger, and Timothy P. L. Roberts. "Consistency of interictal and ictal onset localization using magnetoencephalography in patients with partial epilepsy." Journal of Neurosurgery 98, no. 4 (April 2003): 837–45. http://dx.doi.org/10.3171/jns.2003.98.4.0837.

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Object. The aim of this study was to evaluate the spatial accuracy of interictal magnetoencephalography (MEG) in localizing the primary epileptogenic focus in comparison with alternative MEG-derived estimates such as ictal onset recording or sensory mapping of the periphery where seizures manifest. Methods. During this retrospective study of 12 patients with epilepsy who had undergone successful magnetic source (MS) imaging with the aid of a dual 37-channel biomagnetometer as well as simultaneous MEG/electroencephalography (EEG) recordings, ictal events were observed in five patients and quantitative comparisons of interictal spike and ictal seizure onset source localizations were made. In the eight patients who had presented with sensorimotor seizure, source localization of cortical sites concordant with seizure foci was determined using somatosensory functional mapping, and the results were quantitatively compared with interictal spike source localizations. Interictal spike sources demonstrated on MEG localized to the same region as the corresponding ictal event or somatosensory source localizations. The mean distance between the ictal foci and interictal spike sources was 1.1 ± 0.3 cm. Results of functional somatosensory mapping in patients with sensorimotor seizures demonstrated that seizure sources consistently colocalized with interictal MEG spike sources, with a mean distance of 1.5 ± 0.4 cm. No systematic directional bias was observed. Interictal sources tended to be tightly clustered, and the mean ellipsoid volume, defined by one standard deviation of the source spatial coordinates, was 1 cm3. Conclusions. Interictal spike localizations on MEG were concordant with ictal and, where relevant, functional somatosensory mapping localizations. These findings support the interpretation of interictal spikes on MEG as a useful and effective noninvasive method for localizing primary seizure foci.

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Solekhan, Solekhan, Yoyon K. Suprapto, and Wirawan Wirawan. "Impulsive spike enhancement on gamelan audio using harmonic percussive separation." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 3 (June 1, 2019): 1700. http://dx.doi.org/10.11591/ijece.v9i3.pp1700-1710.

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Impulsive spikes often occur in audio recording of gamelan where most existing methods reduce it. This research offers new method to enhance audio impulsive spike in gamelan music that is able to reduce, eliminate and even strengthen spikes. The process separates audio components into harmonics and percussive components. Percussion component is set to rise or lowered, and the results of the process combined with harmonic components again. This study proposes a new method that allows reducing, eliminating and even amplifying the spike. From the similarity test using the Cosine Distance method, it is seen that spike enhancement through Harmonic Percussive Source Separation (HPSS) has an average Cosine Distance value of 0.0004 or similar to its original, while Mean Square Error (MSE) has an average value of 0.0004 that is very small in average error and also very similar. From the Perceptual Evaluation of Audio Quality (PEAQ) testing with Harmonic Percussive Source Separation (HPSS), it has a better quality with an average Objective Difference Grade (ODG) of -0.24 or Imperceptible.

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Tatar, Özgür, Uğur Çakaloğullari, Gülden Deniz Ateş Atasoy, and Deniz Iştipliler. "Effect of Canopy Structure on Water Use of Wheat (Triticum Aestivum L.) During Post-Anthesis Stage." “Agriculture for Life, Life for Agriculture” Conference Proceedings 1, no. 1 (July 1, 2018): 116–21. http://dx.doi.org/10.2478/alife-2018-0017.

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AbstractWheat, being the main crop in Mediterranean type environments, is grown during winter under rainfed conditions and its yield potential is mostly affected by the amount and distribution of rain. This study is conducted at experimental fields of Ege University, Department of Field Crops in Izmir-Bornova which is characterized as Mediterranean type climate conditions during 2011/2012 and 2012/2013 growing season. Totally 9 canopy structures were generated by different row and line distances. Plant height, total dry weight, tiller number, harvest index, spike number, grain number per spike, thousand grain weight and grain yield were determined after harvest time while digital leaf area index and soil moisture contents were monitoring during specific growth periods to evaluate changes in soil water status by different canopy closer. Increasing in sowing density by different row and in-line distance reduced tiller and spike number per plant. On the other hand, grain number per spike and thousand grain weights were significantly affected by in-line distance instead of row distance. Higher grain yield were obtained from 20x1 cm treatments. Canopy cover speed determined using with digital imaging was not remarkable correlated (r=0.06) with soil moisture content during post-anthesis stage of wheat when higher rain amount is recorded in 2012. However, there was a significant negative correlation (r=0.51) between canopy cover speed and soil water status during post-anthesis stage when the rain amount is limited in 2013. We may suggest that rapid canopy cover lead to negative effect on soil water status via higher transpiration if the rain is limited during post-anthesis stage of wheat.

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Golomb, David. "Models of Neuronal Transient Synchrony During Propagation of Activity Through Neocortical Circuitry." Journal of Neurophysiology 79, no. 1 (January 1, 1998): 1–12. http://dx.doi.org/10.1152/jn.1998.79.1.1.

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Golomb, David. Models of neuronal transient synchrony during propagation of activity through neorcortical circuitry. J. Neurophysiol. 79: 1–12, 1998. Stereotypic paroxysmal discharges that propagate in neocortical tissues after electrical stimulations are used as a probe for studying cortical circuitry. I use modeling to investigate the effects of sparse connectivity, heterogeneity of intrinsic neuronal properties, and synaptic noise on synchronization of evoked propagating neuronal discharges in a network of excitatory, regular spiking neurons with spatially decaying connectivity. The global coherence of the traveling discharge is characterized by the correlation function between spike trains of neurons, averaged over all the pairs of neurons in the system at the same distance. Local coherence of two neurons is characterized by their correlation function averaged over many trials or, for persistent activity, over a long time interval. Spike synchronization between neurons emerges as a result of the transient activity; if activity is persistent, there is no synchrony, and cross-correlation functions are flat. During discharge propagation, system-average cross-correlation between neurons does not depend on their mutual distance except for a time shift. Spike synchronization occurs only when the average number of synapses M a cell receives is large enough. As M increases, there is a cross-over from an asynchronized to a synchronized discharge. Synaptic depression appears to help synchrony; it reduces the M value at the cross-over. The strengths of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartate (NMDA) conductances affect synchrony only weakly. Spike synchronization is robust even with large levels of heterogeneity. Synaptic noise reduces synchrony, but strong synchrony is observed at a noise level that cannot evoke spontaneous discharges. System-average spike synchronization is determined by the levels of sparseness, heterogeneity, and noise, whereas trial-average spike synchronization is determined only by the noise level. Therefore, I predict that experiments will reveal local, two-cell spike synchrony, but not global synchrony.

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Vargas-Irwin, Carlos E., David M. Brandman, Jonas B. Zimmermann, John P. Donoghue, and Michael J. Black. "Spike Train SIMilarity Space (SSIMS): A Framework for Single Neuron and Ensemble Data Analysis." Neural Computation 27, no. 1 (January 2015): 1–31. http://dx.doi.org/10.1162/neco_a_00684.

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Increased emphasis on circuit level activity in the brain makes it necessary to have methods to visualize and evaluate large-scale ensemble activity beyond that revealed by raster-histograms or pairwise correlations. We present a method to evaluate the relative similarity of neural spiking patterns by combining spike train distance metrics with dimensionality reduction. Spike train distance metrics provide an estimate of similarity between activity patterns at multiple temporal resolutions. Vectors of pair-wise distances are used to represent the intrinsic relationships between multiple activity patterns at the level of single units or neuronal ensembles. Dimensionality reduction is then used to project the data into concise representations suitable for clustering analysis as well as exploratory visualization. Algorithm performance and robustness are evaluated using multielectrode ensemble activity data recorded in behaving primates. We demonstrate how spike train SIMilarity space (SSIMS) analysis captures the relationship between goal directions for an eight-directional reaching task and successfully segregates grasp types in a 3D grasping task in the absence of kinematic information. The algorithm enables exploration of virtually any type of neural spiking (time series) data, providing similarity-based clustering of neural activity states with minimal assumptions about potential information encoding models.

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Sugano, Aki, Yutaka Takaoka, Haruyuki Kataguchi, Mika Ohta, Shigemi Kimura, Masatake Araki, Yoshitomo Morinaga, and Yoshihiro Yamamoto. "SARS-CoV-2 Omicron BA.2.75 Variant May Be Much More Infective than Preexisting Variants Based on In Silico Model." Microorganisms 10, no. 10 (October 21, 2022): 2090. http://dx.doi.org/10.3390/microorganisms10102090.

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Previously, we developed a mathematical model via molecular simulation analysis to predict the infectivity of six SARS-CoV-2 variants. In this report, we aimed to predict the relative risk of the recent new variants of SARS-CoV-2 based on our previous research. We subjected Omicron BA.4/5 and BA.2.75 variants of SARS-CoV-2 to the analysis to determine the evolutionary distance of the spike protein gene (S gene) of the variants from the Wuhan variant so as to appreciate the changes in the spike protein. We performed molecular docking simulation analyses of the spike proteins with human angiotensin-converting enzyme 2 (ACE2) to understand the docking affinities of these variants. We then compared the evolutionary distances and the docking affinities of these variants with those of the variants that we had analyzed in our previous research. As a result, BA.2.75 has both the highest docking affinity (ratio per Wuhan variant) and the longest evolutionary distance of the S gene from the Wuhan variant. These results suggest that BA.2.75 infection can spread farther than can infections of preexisting variants.

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Clarke, S. E., R. Naud, A. Longtin, and L. Maler. "Speed-invariant encoding of looming object distance requires power law spike rate adaptation." Proceedings of the National Academy of Sciences 110, no. 33 (July 29, 2013): 13624–29. http://dx.doi.org/10.1073/pnas.1306428110.

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Marquez, Walter Quispe, Masanao Masumura, and Michiyoshi Ae. "The effects of jumping distance on the landing mechanics after a volleyball spike." Sports Biomechanics 8, no. 2 (June 2009): 154–66. http://dx.doi.org/10.1080/14763140902994435.

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Schwarz, Douglas M., Muhammad S. A. Zilany, Melissa Skevington, Nicholas J. Huang, Brian C. Flynn, and Laurel H. Carney. "Semi-supervised spike sorting using pattern matching and a scaled Mahalanobis distance metric." Journal of Neuroscience Methods 206, no. 2 (May 2012): 120–31. http://dx.doi.org/10.1016/j.jneumeth.2012.02.013.

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Chu, Cheng C. J., Ping F. Chien, and Chou P. Hung. "Tuning dissimilarity explains short distance decline of spontaneous spike correlation in macaque V1." Vision Research 96 (March 2014): 113–32. http://dx.doi.org/10.1016/j.visres.2014.01.008.

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Satuvuori, Eero, and Thomas Kreuz. "Which spike train distance is most suitable for distinguishing rate and temporal coding?" Journal of Neuroscience Methods 299 (April 2018): 22–33. http://dx.doi.org/10.1016/j.jneumeth.2018.02.009.

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Yi, Zhengkun, and Yilei Zhang. "A spike train distance-based method to evaluate the response of mechanoreceptive afferents." Neural Computing and Applications 31, no. 10 (March 29, 2018): 6319–30. http://dx.doi.org/10.1007/s00521-018-3465-6.

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Kalimuthu, R., R. C. Mehta, and E. Rathakrishnan. "Investigation of aerodynamic coefficients at Mach 6 over conical, hemispherical and flat-face spiked body." Aeronautical Journal 121, no. 1245 (October 2, 2017): 1711–32. http://dx.doi.org/10.1017/aer.2017.100.

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ABSTRACTA forward spike attached to a blunt body significantly alters its flow field characteristics and influences aerodynamic characteristics at hypersonic flow due to formation of separated flow and re-circulation region around the spiked body. An experimental investigation was performed to measure aerodynamic forces for spikes blunt bodies with a conical, hemispherical and flat-face spike at Mach 6 and at an angle-of-attack range from 0° to 8° and length-to-diameterL/Dratio of spike varies from 0.5 to 2.0, whereLis the length of the spike andDis diameter of blunt body. The shape of the leading edge of the spiked blunt body reveals different types of flow field features in the formation of a shock wave, shear layer, flow separation, re-circulation region and re-attachment shock. They are analysed with the help of schlieren pictures. The shock distance ahead of the hemisphere and the flat-face spike is compared with the analytical solution and is showing satisfactory agreement with the schlieren pictures. The influence of geometrical parameters of the spike, the shape of the spike tip and angle-of-attack on the aerodynamic coefficients are investigated by measuring aerodynamic forces in a hypersonic wind tunnel. It is found that a maximum reduction of drag of about 77% was found for hemisphere spike ofL/D= 2.0 at zero angle-of-attack. Consideration for compensation of increased pitching moment is required to stabilise the aerodynamic forces.

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Choi, Kwang-Eun, Jeong-Min Kim, JeeEun Rhee, Ae Kyung Park, Eun-Jin Kim, and Nam Sook Kang. "Molecular Dynamics Studies on the Structural Characteristics for the Stability Prediction of SARS-CoV-2." International Journal of Molecular Sciences 22, no. 16 (August 13, 2021): 8714. http://dx.doi.org/10.3390/ijms22168714.

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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) affects the COVID-19 pandemic in the world. The spike protein of the various proteins encoded in SARS-CoV-2 binds to human ACE2, fuses, and enters human cells in the respiratory system. Spike protein, however, is highly variable, and many variants were identified continuously. In this study, Korean mutants for spike protein (D614G and D614A-C terminal domain, L455F and F456L-RBD, and Q787H-S2 domain) were investigated in patients. Because RBD in spike protein is related to direct interaction with ACE2, almost all researches were focused on the RBD region or ACE2-free whole domain region. The 3D structure for spike protein complexed with ACE2 was recently released. The stability analysis through RBD distance among each spike protein chain and the binding free energy calculation between spike protein and ACE2 were performed using MD simulation depending on mutant types in 1-, 2-, and 3-open-complex forms. D614G mutant of CT2 domain, showing to be the most prevalent in the global pandemic, showed higher stability in all open-complex forms than the wild type and other mutants. We hope this study will provide an insight into the importance of conformational fluctuation in the whole domain, although RBD is involved in the direct interaction with ACE2.

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Maurya*, Rajendra P., and Champa lal Nagda*. "Influence of Plant Growth Regulators on Growth, Flowering and Corm Yield of Gladiolus (Gladiolus grandiflorus L.) cv. Oscar." HortScience 39, no. 4 (July 2004): 823D—823. http://dx.doi.org/10.21273/hortsci.39.4.823d.

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In a field experiment, uniform sized corms of gladiolus (Gladiolus grandiflorus L. cv. Oscar) were planted in last week of October at a distance of 30 cm. between rows and 20 cm. between plants. The effect of GA (50, 100 ppm), Cycocel (500, 1000) and NAA (50, 100 ppm) on gladiolus plants. It was concluded that foliar application of 100 ppm GA3 at 45 days after corm planting has shown superiority in all vegetative, floral characters and corm & cormel yield viz., plant height (128.53 cm), number of leaves (8.57) per plant, spike length (108.33 cm), spike weight (128.87 g), number of florets (17.60) per spike, size of second florets (15.07 cm), number of spikes (1.67) per plant, size of largest corm (7.52 cm), number of corms (1.80) per plant, number of cormels (11.53) per plant and weight of corms (79.33 g) per plant. Whereas, a highest longevity of florets opening or survival on spike (20.33 days) was recorded in 1000 ppm Cycocel.

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Raju, Venkateshwarla Rama. "Investigation of multi-site micro recordings of subthalamic nucleus neurons using machine learning MER with DBS in Parkinson`s – A simulation study." IP Indian Journal of Neurosciences 7, no. 4 (January 15, 2022): 287–91. http://dx.doi.org/10.18231/j.ijn.2021.052.

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Multineural spikes were acquired with a multisite electrode placed in the hippocampus pyramidal cell layer of non-primate anesthetized snitch animals. If the impedance of each electrode-site is relatively low and the distance amongst electrode sites is appropriately miniatured, a spike generated by a neuron is parallelly recorded at multielectrode sites with different amplitudes. The covariance between the spike of the at each electrode-point and a template was computed as a damping-factor due to the volume conduction of the spike from the neuron to electrode-site. Computed damping factors were vectorized and analyzed by simple but elegant hierarchical-clustering using a multidimensional statistical-test. Since a cluster of damping vectors was shown to correspond to an antidromically identified neuron, spikes of distinct neurons are classified by suggesting to the scatterings of damping vectors. Errors in damping vector computing due to partially overlapping spikes were minimized by successively subtracting preceding spikes from raw data. Clustering errors due to complex-spike-bursts (i.e., spikes with variable-amplitudes) were prevented by detecting such bursts and using only the first spike of a burst for clustering.

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Larson, Eric, Cyrus P. Billimoria, and Kamal Sen. "A Biologically Plausible Computational Model for Auditory Object Recognition." Journal of Neurophysiology 101, no. 1 (January 2009): 323–31. http://dx.doi.org/10.1152/jn.90664.2008.

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Object recognition is a task of fundamental importance for sensory systems. Although this problem has been intensively investigated in the visual system, relatively little is known about the recognition of complex auditory objects. Recent work has shown that spike trains from individual sensory neurons can be used to discriminate between and recognize stimuli. Multiple groups have developed spike similarity or dissimilarity metrics to quantify the differences between spike trains. Using a nearest-neighbor approach the spike similarity metrics can be used to classify the stimuli into groups used to evoke the spike trains. The nearest prototype spike train to the tested spike train can then be used to identify the stimulus. However, how biological circuits might perform such computations remains unclear. Elucidating this question would facilitate the experimental search for such circuits in biological systems, as well as the design of artificial circuits that can perform such computations. Here we present a biologically plausible model for discrimination inspired by a spike distance metric using a network of integrate-and-fire model neurons coupled to a decision network. We then apply this model to the birdsong system in the context of song discrimination and recognition. We show that the model circuit is effective at recognizing individual songs, based on experimental input data from field L, the avian primary auditory cortex analog. We also compare the performance and robustness of this model to two alternative models of song discrimination: a model based on coincidence detection and a model based on firing rate.

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Akgün, İlknur, Tuğçe Ayşe Karakoca, and Ruziye Karaman. "Farklı Gamma Işını Dozlarının İki Sıralı Arpada (Hordeum vulgare L.) Bazı Tarımsal Özellikler Üzerine Etkisi." Turkish Journal of Agriculture - Food Science and Technology 7, sp2 (December 21, 2019): 86. http://dx.doi.org/10.24925/turjaf.v7isp2.86-92.3152.

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In this study, the effect of different doses of gamma ray (200, 300, 400 and 500 Gy) applied on seeds of Tarm-92 two-row barley varieties on some agricultural properties were investigated. The research was conducted in 2016-2017 vegetation period under Isparta conditions. In M1 generation, normal and abnormal plants are harvested separately according to the spike and plant appearance at each dose and 9 different [200, 200 A, 300, 300 A, 400, 400 A, 400 A (plants with double spike formation and branching tendency in spike Ç.B.) 500 and 500 A gray] groups were formed. A total of 10 plots with control (no irradiation) were included in the M2 generation. Results showed that the effect of gamma ray application on the thousand grain weight, test weight, ratio of husk and protein content was significant statistically. While increasing the ratio of husk and protein content, gamma ray application significantly reduced the weight of a thousand grains and test weight. In this research, plant height, spike length, number of grain per spike and weight of grain per spike were investigated on a single plant. Discriminant analysis was done and distance between groups was determined. The rate of plants similar to control in examined characters in M2 generation is 400 Gy 7.83%, 200 Gy 10%, 300 Gy 19.60% and 500 Gy 22.22%. When the coefficients containing linear separation functions are examined, it is determined that the most effective feature is spike length.

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Valadés, David, José Manuel Palao, Ángel Aúnsolo, and Aurelio Ureña. "Correlation between ball speed of the spike and the strength condition of a professional women’s volleyball team during the season." Kinesiology 48, no. 1 (2016): 87–94. http://dx.doi.org/10.26582/k.48.1.7.

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The aim of this paper was to study the relationship between spike speed and the players’ characteristics, anthropometrics, and strength levels throughout the season for a women’s professional volleyball team. Players from a Spanish first division team performed a battery of tests evaluating anthropometric characteristics, strength performance, and spike speed at the beginning, in the middle, and at the end of one competitive season. The variables were: age; training experience; height; one-hand standing reach height; body mass; body mass index; height of the vertical jump with an approach (spike jump); muscle percentage of arms; 1 repetition maximum (1RM) bench press; 1RM pullover; overhead medicine ball throws for distance using 1, 2, 3, 4, and 5 kg; spike angles; and speed of standing and jump spikes. Results showed that players’ general strength (bench press and pullover) and power parameters (medicine ball throws) increased throughout theseason, while speed of the jump did not improve. The variable that best predicted the jump spike speed at all the three time points in the season was the standing spike speed. The players’ training increased their strength and upper-body power, but these improvements were not transferred to players’ hitting speed ability. Push-pull and throwing exercises were not specific enough to improve the hitting ability of the female senior volleyball players.

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Choi, Kwang-Eun, Jeong-Min Kim, Jee Eun Rhee, Ae Kyung Park, Eun-Jin Kim, Cheon Kwon Yoo, and Nam Sook Kang. "Molecular Dynamics Studies on the Structural Stability Prediction of SARS-CoV-2 Variants Including Multiple Mutants." International Journal of Molecular Sciences 23, no. 9 (April 29, 2022): 4956. http://dx.doi.org/10.3390/ijms23094956.

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Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has caused the Coronavirus Disease (COVID-19) pandemic worldwide. The spike protein in SARS-CoV-2 fuses with and invades cells in the host respiratory system by binding to angiotensin-converting enzyme 2 (ACE2). The spike protein, however, undergoes continuous mutation from a D614G single mutant to an omicron variant, including multiple mutants. In this study, variants, including multiple mutants (double, triple mutants, B.1.620, delta, alpha, delta_E484Q, mu, and omicron) were investigated in patients. The 3D structure of the full-length spike protein was used in conformational analysis depending on the SARS-CoV-2 variants. The structural stability of the variant types was analyzed based on the distance between the receptor-binding domain (RBD) of each chain in the spike protein and the binding free energy between the spike protein and bound ACE2 in the one-, two-, and three-open-complex forms using molecular dynamics (MD) simulation. Omicron variants, the most prevalent in the recent history of the global pandemic, which consist of 32 mutations, showed higher stability in all open-complex forms compared with that of the wild type and other variants. We suggest that the conformational stability of the spike protein is the one of the important determinants for the differences in viral infectivity among variants, including multiple mutants.

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Daghigh, Ramin G., and Gabor Kunstatter. "Spacetime Metrics and Ringdown Waveforms for Galactic Black Holes Surrounded by a Dark Matter Spike." Astrophysical Journal 940, no. 1 (November 1, 2022): 33. http://dx.doi.org/10.3847/1538-4357/ac940b.

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Abstract Theoretical models suggest the existence of a dark matter spike surrounding the supermassive black holes at the core of galaxies. The spike density is thought to obey a power law that starts at a few times the black hole horizon radius and extends to a distance, R sp, of the order of a kiloparsec. We use the Tolman–Oppenheimer–Volkoff equations to construct the spacetime metric representing a black hole surrounded by such a dark matter spike. We consider the dark matter to be a perfect fluid, but make no other assumption about its nature. The assumed power-law density provides in principle three parameters with which to work: the power-law exponent γ sp, the external radius R sp, and the spike density ρ DM sp at R sp. These in turn determine the total mass of the spike. We focus on Sagittarius A* and M87 for which some theoretical and observational bounds exist on the spike parameters. Using these bounds in conjunction with the metric obtained from the Tolman–Oppenheimer–Volkoff equations, we investigate the possibility of detecting the dark matter spikes surrounding these black holes via the gravitational waves emitted at the ringdown phase of black hole perturbations. Our results suggest that if the spike to black hole mass ratio is roughly constant, greater mass black holes require relatively smaller spike densities to yield potentially observable signals. We find that is unlikely for the spike in M87 to be detected via the ringdown waveform with currently available techniques unless its mass is roughly an order of magnitude larger than existing observational estimates. However, given that the signal increases with black hole mass, dark matter spikes might be observable for more massive galactic black holes in the not too distant future.

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Kociuba, Wanda, Wieslaw Mądry, Aneta Kramek, Krzysztof Ukalski, and Marcin Studnicki. "Multtvariate diversity of Polish winter triticale cultivars for spike and other traits." Plant Breeding and Seed Science 62, no. 1 (January 1, 2010): 31–42. http://dx.doi.org/10.2478/v10129-011-0003-4.

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Multtvariate diversity of Polish winter triticale cultivars for spike and other traits The objective of the present study was to determine the extent and pattern of genotypic diversity for six spike quantitative characters and two other traits in 36 winter triticale cultivars released in Poland, to classify the cultivars into similarity groups (clusters) and to identify those traits, among the studied ones, which mostly discriminated distinguished groups of cultivars. The 36 cultivars, released in the period from 1982 to 1999, were evaluated across three years 2002-2004 at the Experimental Field Station in Czesławice near Nałęczów, Poland. The experiments were carried out on the brown soil with loess subsoil. In each year the one-replicated experimental design was used with 2 m2 plots, rows 20 cm apart, and dense sowing using about 2 cm spacing of seeds. Analyses of variance for each trait data according to the random model (both cultivars and years were assumed to be random factors) were done. To classify and characterize genotypic diversity of the cultivars for the eight traits, the pattern analysis was used. It involved both cluster analysis using Ward's procedure with a measure of the multivariate similarity among cultivars being Squared Euclidean Distance and canonical variate analysis (CVA) on the basis of cultivar BLUPs for the original traits. Quite different groups of cultivars for the studied traits were found, specially one group was substantially distanced to the others. As it was shown by CVA, spike length and number of spikelets per spike as negatively correlated with number of grains per spikelet in the studied set of the cultivars relatively largest contributed to overall differentiation of the distinguished eight groups and then, these traits best discriminated among the eight cultivar groups in the term of Mahalanobis distance for the considered traits. The 1000 grain weight and grain protein content much less contributed to overall discrimination of the cultivar groups than the previous four traits. The most important agronomic traits characterizing productivity of the spike grain weight and its two components, e.g. number of grains per spikelet and number of grains per spike had least discriminating power for the groups of cultivars. Grain yield per unit area of cereals is a result of spike grain yield and the number of spikes per unit area. In these studies of winter triticale cultivar diversity only grain spike yield and its components were included. Thus, the presented study are a primary evaluating of phenotypic diversity in the cultivars. The further study on the cultivar diversity evaluation for grain yield per unit area and its components is necessary.

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ISHIKANE, HIROSHI, AKIO KAWANA, and MASAO TACHIBANA. "Short- and long-range synchronous activities in dimming detectors of the frog retina." Visual Neuroscience 16, no. 6 (November 1999): 1001–14. http://dx.doi.org/10.1017/s0952523899166033.

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In the visual system, nearby neurons of similar functional type have a tendency to fire synchronously. Cross-correlation analysis of spike discharges recorded from pairs of neurons has revealed that the synchronized activity is frequently associated with oscillatory firing patterns. However, the underlying neural mechanisms and functions of synchronization and oscillations are not well understood. In the present study, we simultaneously recorded spike discharges from multiple OFF-sustained type ganglion cells with no antagonistic surround (the dimming detectors) of the frog retina using a planar multi-electrode array and analyzed the temporal properties of light-evoked spike discharges. With full-field, temporally modulated diffuse illumination, cross-correlation analysis revealed the presence of the synchronous oscillatory pattern. The strength of the synchronized activity decreased slightly with increased intercellular distance. Synchronized spike discharges were detected even in cell pairs more than 2 mm apart. The frequency of oscillations peaked at approximately 30 Hz. The shuffled cross-correlogram was nearly flat, indicating that the synchronous oscillatory activities are most probably of neural origin. When GABAA antagonists were applied to the retina, oscillations were suppressed almost completely and the strength of the synchronized activity decreased with increased intercellular distance more sharply than control. When small spot illumination was applied to the overlapping receptive fields of an adjacent cell pair, a weak synchronized activity was evoked without accompanying oscillations. The same cell pair generated a strong synchronized activity accompanied with oscillations with full-field illumination. Our results suggest that local synchronous activities are generated via short-range neural interactions, and that the oscillatory activities are induced by long-range neural interactions and may contribute to the establishment of synchrony between widely separated neuronal populations.

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Rao, Rajesh P. N., and Terrence J. Sejnowski. "Spike-Timing-Dependent Hebbian Plasticity as Temporal Difference Learning." Neural Computation 13, no. 10 (October 1, 2001): 2221–37. http://dx.doi.org/10.1162/089976601750541787.

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A spike-timing-dependent Hebbian mechanism governs the plasticity of recurrent excitatory synapses in the neocortex: synapses that are activated a few milliseconds before a postsynaptic spike are potentiated, while those that are activated a few milliseconds after are depressed. We show that such a mechanism can implement a form of temporal difference learning for prediction of input sequences. Using a biophysical model of a cortical neuron, we show that a temporal difference rule used in conjunction with dendritic backpropagating action potentials reproduces the temporally asymmetric window of Hebbian plasticity observed physiologically. Furthermore, the size and shape of the window vary with the distance of the synapse from the soma. Using a simple example, we show how a spike-timing-based temporal difference learning rule can allow a network of neocortical neurons to predict an input a few milliseconds before the input's expected arrival.

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d’Humières, G., and J. L. Stollery. "Drag reduction on a spiked body at hypersonic speed." Aeronautical Journal 114, no. 1152 (February 2010): 113–19. http://dx.doi.org/10.1017/s0001924000003584.

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AbstractFitting a spike on a blunt body provides a drag reduction at supersonic and hypersonic speeds. In this study, the laminar flow over a spiked, conical body terminated by a spherical cap, inspired by the Apollo re-entry capsule design, was investigated using a hypersonic wind tunnel. Schlieren pictures revealed the absence of flow unsteadiness for the range of spike lengths tested, and force measurements showed a maximum reduction of 77% of the unspiked body drag.A simple theoretical model based on the pressure drag generated by a solid cone showed good agreement with the experimental data. The measured shock stand-off distance agreed well with predictions.

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Houghton, Conor. "Calculating mutual information for spike trains and other data with distances but no coordinates." Royal Society Open Science 2, no. 5 (May 2015): 140391. http://dx.doi.org/10.1098/rsos.140391.

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Many important data types, such as the spike trains recorded from neurons in typical electrophysiological experiments, have a natural notion of distance or similarity between data points, even though there is no obvious coordinate system. Here, a simple Kozachenko–Leonenko estimator is derived for calculating the mutual information between datasets of this type.

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Brasselet, Romain, Roland S. Johansson, and Angelo Arleo. "Quantifying Neurotransmission Reliability Through Metrics-Based Information Analysis." Neural Computation 23, no. 4 (April 2011): 852–81. http://dx.doi.org/10.1162/neco_a_00099.

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We set forth an information-theoretical measure to quantify neurotransmission reliability while taking into full account the metrical properties of the spike train space. This parametric information analysis relies on similarity measures induced by the metrical relations between neural responses as spikes flow in. Thus, in order to assess the entropy, the conditional entropy, and the overall information transfer, this method does not require any a priori decoding algorithm to partition the space into equivalence classes. It therefore allows the optimal parameters of a class of distances to be determined with respect to information transmission. To validate the proposed information-theoretical approach, we study precise temporal decoding of human somatosensory signals recorded using microneurography experiments. For this analysis, we employ a similarity measure based on the Victor-Purpura spike train metrics. We show that with appropriate parameters of this distance, the relative spike times of the mechanoreceptors’ responses convey enough information to perform optimal discrimination—defined as maximum metrical information and zero conditional entropy—of 81 distinct stimuli within 40 ms of the first afferent spike. The proposed information-theoretical measure proves to be a suitable generalization of Shannon mutual information in order to consider the metrics of temporal codes explicitly. It allows neurotransmission reliability to be assessed in the presence of large spike train spaces (e.g., neural population codes) with high temporal precision.

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Tezuka, Taro, and Christophe Claramunt. "Kernel Analysis for Estimating the Connectivity of a Network with Event Sequences." Journal of Artificial Intelligence and Soft Computing Research 7, no. 1 (January 1, 2017): 17–31. http://dx.doi.org/10.1515/jaiscr-2017-0002.

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AbstractEstimating the connectivity of a network from events observed at each node has many applications. One prominent example is found in neuroscience, where spike trains (sequences of action potentials) are observed at each neuron, but the way in which these neurons are connected is unknown. This paper introduces a novel method for estimating connections between nodes using a similarity measure between sequences of event times. Specifically, a normalized positive definite kernel defined on spike trains was used. The proposed method was evaluated using synthetic and real data, by comparing with methods using transfer entropy and the Victor-Purpura distance. Synthetic data was generated using CERM (Coupled Escape-Rate Model), a model that generates various spike trains. Real data recorded from the visual cortex of an anaesthetized cat was analyzed as well. The results showed that the proposed method provides an effective way of estimating the connectivity of a network when the time sequences of events are the only available information.

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Journal articles on the topic 'SPIKE-distance'

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