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Sample records for recurring spatiotemporal activity

  1. Plasticity of recurring spatiotemporal activity patterns in cortical networks

    NASA Astrophysics Data System (ADS)

    Madhavan, Radhika; Chao, Zenas C.; Potter, Steve M.

    2007-09-01

    How do neurons encode and store information for long periods of time? Recurring patterns of activity have been reported in various cortical structures and were suggested to play a role in information processing and memory. To study the potential role of bursts of action potentials in memory mechanisms, we investigated patterns of spontaneous multi-single-unit activity in dissociated rat cortical cultures in vitro. Spontaneous spikes were recorded from networks of approximately 50 000 neurons and glia cultured on a grid of 60 extracellular substrate- embedded electrodes (multi-electrode arrays). These networks expressed spontaneous culture- wide bursting from approximately one week in vitro. During bursts, a large portion of the active electrodes showed elevated levels of firing. Spatiotemporal activity patterns within spontaneous bursts were clustered using a correlation-based clustering algorithm, and the occurrences of these burst clusters were tracked over several hours. This analysis revealed spatiotemporally diverse bursts occurring in well-defined patterns, which remained stable for several hours. Activity evoked by strong local tetanic stimulation resulted in significant changes in the occurrences of spontaneous bursts belonging to different clusters, indicating that the dynamical flow of information in the neuronal network had been altered. The diversity of spatiotemporal structure and long-term stability of spontaneous bursts together with their plastic nature strongly suggests that such network patterns could be used as codes for information transfer and the expression of memories stored in cortical networks.

  2. Internally Recurring Hippocampal Sequences as a Population Template of Spatiotemporal Information

    PubMed Central

    Villette, Vincent; Malvache, Arnaud; Tressard, Thomas; Dupuy, Nathalie; Cossart, Rosa

    2015-01-01

    Summary The hippocampus is essential for spatiotemporal cognition. Sequences of neuronal activation provide a substrate for this fundamental function. At the behavioral timescale, these sequences have been shown to occur either in the presence of successive external landmarks or through internal mechanisms within an episodic memory task. In both cases, activity is externally constrained by the organization of the task and by the size of the environment explored. Therefore, it remains unknown whether hippocampal activity can self-organize into a default mode in the absence of any external memory demand or spatiotemporal boundary. Here we show that, in the presence of self-motion cues, a population code integrating distance naturally emerges in the hippocampus in the form of recurring sequences. These internal dynamics clamp spontaneous travel since run distance distributes into integer multiples of the span of these sequences. These sequences may thus guide navigation when external landmarks are reduced. PMID:26494280

  3. Discovering frequently recurring movement sequences in team-sport athlete spatiotemporal data.

    PubMed

    Sweeting, Alice J; Aughey, Robert J; Cormack, Stuart J; Morgan, Stuart

    2017-02-09

    Athlete external load is typically analysed from predetermined movement thresholds. The combination of movement sequences and differences in these movements between playing positions is also currently unknown. This study developed a method to discover the frequently recurring movement sequences across playing position during matches. The external load of 12 international female netball athletes was collected by a local positioning system during four national-level matches. Velocity, acceleration and angular velocity were calculated from positional (X, Y) data, clustered via one-dimensional k-means and assigned a unique alphabetic label. Combinations of velocity, acceleration and angular velocity movement were compared using the Levenshtein distance and similarities computed by the longest common substring problem. The contribution of each movement sequence, according to playing position and relative to the wider data set, was then calculated via the Minkowski distance. A total of 10 frequently recurring combinations of movement were discovered, regardless of playing position. Only the wing attack, goal attack and goal defence playing positions are closely related. We developed a technique to discover the movement sequences, according to playing position, performed by elite netballers. This methodology can be extended to discover the frequently recurring movements within other team sports and across levels of competition.

  4. Temperature and density structure of a recurring active region jet

    NASA Astrophysics Data System (ADS)

    Mulay, Sargam M.; Zanna, Giulio Del; Mason, Helen

    2017-01-01

    Aims: We present a study of a recurring jet observed on October 31, 2011 by the Atmosphereic Imaging Assembly (AIA) on board the Solar Dynamic Observatory, the X-ray Telescope (XRT) and EUV Imaging Spectrometer (EIS) on board Hinode. We discuss the physical parameters of the jet that are obtained using imaging and spectroscopic observations, such as density, differential emission measure, peak temperature, velocity, and filling factor. Methods: A differential emission measure (DEM) analysis was performed at the region of the jet spire and the footpoint using EIS observations and also by combining AIA and XRT observations. The resulting EIS DEM curves were compared to those obtained with AIA-XRT. The DEM curves were used to create synthetic spectra with the CHIANTI atomic database. The predicted total count rates for each AIA channel were compared with the observed count rates. The effects of varying elemental abundances and the temperature range for the DEM inversion were investigated. Spectroscopic diagnostics were used to obtain an electron number density distribution for the jet spire and the jet footpoint. Results: The plasma along the line of sight in the jet spire and jet footpoint was found to be peak at 2.0 MK (log T [K] = 6.3). We calculated electron densities using the Fe XII (λ186/λ195) line ratio in the region of the spire (Ne = 7.6 × 1010 cm-3) and the footpoint (1.1 × 1011 cm-3). The plane-of-sky velocity of the jet is found to be 524 km s-1. The resulting EIS DEM values are in good agreement with those obtained from AIA-XRT. The synthetic spectra contributing to each AIA channel confirms the multi-thermal nature of the AIA channels in both regions. There is no indication of high temperatures, such as emission from Fe XVII (λ254.87) (log T [K] = 6.75) seen in the jet spire. In the case of the jet footpoint, synthetic spectra predict weak contributions from Ca XVII (λ192.85) and Fe XVII (λ254.87). With further investigation, we confirmed

  5. Effects of Recurring Droughts on Extracellular Enzyme Activity in Mountain Grassland

    NASA Astrophysics Data System (ADS)

    Fuchslueger, L.; Bahn, M.; Kienzl, S.; Hofhansl, F.; Schnecker, J.; Richter, A.

    2015-12-01

    Water availability is a key factor for biogeochemical processes and determines microbial activity and functioning, and thereby organic matter decomposition in soils by affecting the osmotic potential, soil pore connectivity, substrate diffusion and nutrient availability. Low water availability during drought periods therefore directly affects microbial activity. Recurring drought periods likely induce shifts in microbial structure that might be reflected in altered responses of microbial turnover of organic matter by extracellular enzymes. To study this we measured a set of potential extracellular enzyme activity rates (cellobiohydrolase CBH; leucine-amino-peptidase LAP; phosphatase PHOS; phenoloxidase POX), in grassland soils that were exposed to extreme experimental droughts during the growing seasons of up to five subsequent years. During the first drought period after eight weeks of rain exclusion all measured potential enzyme activities were significantly decreased. In parallel, soil extractable organic carbon and nitrogen concentrations increased and microbial community structure, determined by phospholipid fatty acid analysis, changed. In soils that were exposed to two and three drought periods only PHOS decreased. After four years of drought again CBH, PHOS and POX decreased, while LAP was unaffected; after five years of drought PHOS and POX decreased and CBH and LAP remained stable. Thus, our results suggest that recurring extreme drought events can cause different responses of extracellular enzyme activities and that the responses change over time. We will discuss whether and to what degree these changes were related to shifts in microbial community composition. However, independent of whether a solitary or a recurrent drought was imposed, in cases when enzyme activity rates were altered during drought, they quickly recovered after rewetting. Overall, our data suggest that microbial functioning in mountain grassland is sensitive to drought, but highly

  6. Spatiotemporal Data Mining, Analysis, and Visualization of Human Activity Data

    ERIC Educational Resources Information Center

    Li, Xun

    2012-01-01

    This dissertation addresses the research challenge of developing efficient new methods for discovering useful patterns and knowledge in large volumes of electronically collected spatiotemporal activity data. I propose to analyze three types of such spatiotemporal activity data in a methodological framework that integrates spatial analysis, data…

  7. Spatio-temporal modeling of Active Layer Thickness

    NASA Astrophysics Data System (ADS)

    Touyz, J.; Apanasovich, T. V.; Streletskiy, D. A.; Shiklomanov, N. I.

    2015-12-01

    Arctic Regions are experiencing an unprecedented rate of environmental and climate change. The active layer (the uppermost layer of soil between the atmosphere and permafrost that freezes in winter and thaws in summer) is sensitive to both climate and environmental changes and plays an important role in the functioning of Arctic ecosystems, planning, and economic activities. Knowledge about spatio-temporal variability of ALT is crucial for environmental and engineering applications. The objective of this study is to provide the methodology to model and estimate spatio-temporal variation in the active layer thickness (ALT) at several sites located in the Circumpolar region spanning the Alaska North Slope, and to demonstrate its use in spatio-temporal interpolation as well as time-forward prediction. In our data analysis we estimate a parametric trend and examine residuals for the presence of spatial and temporal dependence. We propose models that provide a description of residual space-time variability in ALT. Formulations that take into account interaction among spatial and temporal components are also developed. Moreover, we compare our models to naive models in which residual spatio-temporal and temporal correlations are not considered. The predicted root mean squared and absolute errors are significantly reduced when our approach is employed. While the methodology is developed in the context of ALT, it can also be applied to model and predict other environmental variables which use similar spatio-temporal sampling designs.

  8. Tensor analysis methods for activity characterization in spatiotemporal data

    SciTech Connect

    Haass, Michael Joseph; Van Benthem, Mark Hilary; Ochoa, Edward M.

    2014-03-01

    Tensor (multiway array) factorization and decomposition offers unique advantages for activity characterization in spatio-temporal datasets because these methods are compatible with sparse matrices and maintain multiway structure that is otherwise lost in collapsing for regular matrix factorization. This report describes our research as part of the PANTHER LDRD Grand Challenge to develop a foundational basis of mathematical techniques and visualizations that enable unsophisticated users (e.g. users who are not steeped in the mathematical details of matrix algebra and mulitway computations) to discover hidden patterns in large spatiotemporal data sets.

  9. Active region 11748: Recurring X-class flares, large scale dimmings and waves.

    NASA Astrophysics Data System (ADS)

    Davey, Alisdair R.; Malanushenko, Anna; McIntosh, Scott W.

    2014-06-01

    AR 11748 was a relatively compact active region that crossed the solar disk between 05/14/2013 and 05/26/2013. Despite its size it produced a number X-class flares, and global scale eruptive events that were captured by the SDO Feature Finding Team's (FFT) Dimming Region Detector. Using the results of this module and other FFT modules, we present an analysis of the this AR region and investigate why it was so globally impactful.

  10. Mononucleosis: Can It Recur?

    MedlinePlus

    ... once you got mono you couldn't get it again. Answers from James M. Steckelberg, M.D. ... people who have infectious mononucleosis, or mono, get it only once. Rarely, however, mononucleosis symptoms may recur ...

  11. Emergence of reproducible spatiotemporal activity during motor learning.

    PubMed

    Peters, Andrew J; Chen, Simon X; Komiyama, Takaki

    2014-06-12

    The motor cortex is capable of reliably driving complex movements yet exhibits considerable plasticity during motor learning. These observations suggest that the fundamental relationship between motor cortex activity and movement may not be fixed but is instead shaped by learning; however, to what extent and how motor learning shapes this relationship are not fully understood. Here we addressed this issue by using in vivo two-photon calcium imaging to monitor the activity of the same population of hundreds of layer 2/3 neurons while mice learned a forelimb lever-press task over two weeks. Excitatory and inhibitory neurons were identified by transgenic labelling. Inhibitory neuron activity was relatively stable and balanced local excitatory neuron activity on a movement-by-movement basis, whereas excitatory neuron activity showed higher dynamism during the initial phase of learning. The dynamics of excitatory neurons during the initial phase involved the expansion of the movement-related population which explored various activity patterns even during similar movements. This was followed by a refinement into a smaller population exhibiting reproducible spatiotemporal sequences of activity. This pattern of activity associated with the learned movement was unique to expert animals and not observed during similar movements made during the naive phase, and the relationship between neuronal activity and individual movements became more consistent with learning. These changes in population activity coincided with a transient increase in dendritic spine turnover in these neurons. Our results indicate that a novel and reproducible activity-movement relationship develops as a result of motor learning, and we speculate that synaptic plasticity within the motor cortex underlies the emergence of reproducible spatiotemporal activity patterns for learned movements. These results underscore the profound influence of learning on the way that the cortex produces movements.

  12. Assessing global vegetation activity using spatio-temporal Bayesian modelling

    NASA Astrophysics Data System (ADS)

    Mulder, Vera L.; van Eck, Christel M.; Friedlingstein, Pierre; Regnier, Pierre A. G.

    2016-04-01

    This work demonstrates the potential of modelling vegetation activity using a hierarchical Bayesian spatio-temporal model. This approach allows modelling changes in vegetation and climate simultaneous in space and time. Changes of vegetation activity such as phenology are modelled as a dynamic process depending on climate variability in both space and time. Additionally, differences in observed vegetation status can be contributed to other abiotic ecosystem properties, e.g. soil and terrain properties. Although these properties do not change in time, they do change in space and may provide valuable information in addition to the climate dynamics. The spatio-temporal Bayesian models were calibrated at a regional scale because the local trends in space and time can be better captured by the model. The regional subsets were defined according to the SREX segmentation, as defined by the IPCC. Each region is considered being relatively homogeneous in terms of large-scale climate and biomes, still capturing small-scale (grid-cell level) variability. Modelling within these regions is hence expected to be less uncertain due to the absence of these large-scale patterns, compared to a global approach. This overall modelling approach allows the comparison of model behavior for the different regions and may provide insights on the main dynamic processes driving the interaction between vegetation and climate within different regions. The data employed in this study encompasses the global datasets for soil properties (SoilGrids), terrain properties (Global Relief Model based on SRTM DEM and ETOPO), monthly time series of satellite-derived vegetation indices (GIMMS NDVI3g) and climate variables (Princeton Meteorological Forcing Dataset). The findings proved the potential of a spatio-temporal Bayesian modelling approach for assessing vegetation dynamics, at a regional scale. The observed interrelationships of the employed data and the different spatial and temporal trends support

  13. Spatio-temporal activity of lightnings over Greece

    NASA Astrophysics Data System (ADS)

    Nastos, P. T.; Matsangouras, I. T.; Chronis, T. G.

    2012-04-01

    Extreme precipitation events are always associated with convective weather conditions driving to intense lightning activity: Cloud to Ground (CG), Ground to Cloud (GC) and Cloud to Cloud (CC). Thus, the study of lightnings, which typically occur during thunderstorms, gives evidence of the spatio-temporal variability of intense precipitation. Lightning is a natural phenomenon in the atmosphere, being a major cause of storm related with deaths and main trigger of forest fires during dry season. Lightning affects the many electrochemical systems of the body causing nerve damage, memory loss, personality change, and emotional problems. Besides, among the various nitrogen oxides sources, the contribution from lightning likely represents the largest uncertainty. An operational lightning detection network (LDN) has been established since 2007 by HNMS, consisting of eight time-of-arrival sensors (TOA), spatially distributed across Greek territory. In this study, the spatial and temporal variability of recorded lightnings (CG, GC and CC) are analyzed over Greece, during the period from January 14, 2008 to December 31, 2009, for the first time. The data for retrieving the location and time-of-occurrence of lightning were acquired from Hellenic National Meteorological Service (HNMS). In addition to the analysis of spatio-temporal activity over Greece, the HNMS-LDN characteristics are also presented. The results of the performed analysis reveal the specific geographical sub-regions associated with lightnings incidence. Lightning activity occurs mainly during the autumn season, followed by summer and spring. Higher frequencies of flashes appear over Ionian and Aegean Sea than over land during winter period against continental mountainous regions during summer period.

  14. Controlling spatiotemporal chaos in active dissipative-dispersive nonlinear systems

    NASA Astrophysics Data System (ADS)

    Gomes, S. N.; Pradas, M.; Kalliadasis, S.; Papageorgiou, D. T.; Pavliotis, G. A.

    2015-08-01

    We present an alternative methodology for the stabilization and control of infinite-dimensional dynamical systems exhibiting low-dimensional spatiotemporal chaos. We show that with an appropriate choice of time-dependent controls we are able to stabilize and/or control all stable or unstable solutions, including steady solutions, traveling waves (single and multipulse ones or bound states), and spatiotemporal chaos. We exemplify our methodology with the generalized Kuramoto-Sivashinsky equation, a paradigmatic model of spatiotemporal chaos, which is known to exhibit a rich spectrum of wave forms and wave transitions and a rich variety of spatiotemporal structures.

  15. Spatiotemporal order and emergent edge currents in active spinner materials

    PubMed Central

    van Zuiden, Benjamin C.; Paulose, Jayson; Irvine, William T. M.; Bartolo, Denis; Vitelli, Vincenzo

    2016-01-01

    Collections of interacting, self-propelled particles have been extensively studied as minimal models of many living and synthetic systems from bird flocks to active colloids. However, the influence of active rotations in the absence of self-propulsion (i.e., spinning without walking) remains less explored. Here, we numerically and theoretically investigate the behavior of ensembles of self-spinning dimers. We find that geometric frustration of dimer rotation by interactions yields spatiotemporal order and active melting with no equilibrium counterparts. At low density, the spinning dimers self-assemble into a triangular lattice with their orientations phase-locked into spatially periodic phases. The phase-locked patterns form dynamical analogs of the ground states of various spin models, transitioning from the three-state Potts antiferromagnet at low densities to the striped herringbone phase of planar quadrupoles at higher densities. As the density is raised further, the competition between active rotations and interactions leads to melting of the active spinner crystal. Emergent edge currents, whose direction is set by the chirality of the active spinning, arise as a nonequilibrium signature of the transition to the active spinner liquid and vanish when the system eventually undergoes kinetic arrest at very high densities. Our findings may be realized in systems ranging from liquid crystal and colloidal experiments to tabletop realizations using macroscopic chiral grains. PMID:27803323

  16. Prediction of Spatiotemporal Patterns of Neural Activity from Pairwise Correlations

    SciTech Connect

    Marre, O.; El Boustani, S.; Fregnac, Y.; Destexhe, A.

    2009-04-03

    We designed a model-based analysis to predict the occurrence of population patterns in distributed spiking activity. Using a maximum entropy principle with a Markovian assumption, we obtain a model that accounts for both spatial and temporal pairwise correlations among neurons. This model is tested on data generated with a Glauber spin-glass system and is shown to correctly predict the occurrence probabilities of spatiotemporal patterns significantly better than Ising models only based on spatial correlations. This increase of predictability was also observed on experimental data recorded in parietal cortex during slow-wave sleep. This approach can also be used to generate surrogates that reproduce the spatial and temporal correlations of a given data set.

  17. Photoactivated Spatiotemporally-Responsive Nanosensors of in Vivo Protease Activity.

    PubMed

    Dudani, Jaideep S; Jain, Piyush K; Kwong, Gabriel A; Stevens, Kelly R; Bhatia, Sangeeta N

    2015-12-22

    Proteases play diverse and important roles in physiology and disease, including influencing critical processes in development, immune responses, and malignancies. Both the abundance and activity of these enzymes are tightly regulated and highly contextual; thus, in order to elucidate their specific impact on disease progression, better tools are needed to precisely monitor in situ protease activity. Current strategies for detecting protease activity are focused on functionalizing synthetic peptide substrates with reporters that emit detection signals following peptide cleavage. However, these activity-based probes lack the capacity to be turned on at sites of interest and, therefore, are subject to off-target activation. Here we report a strategy that uses light to precisely control both the location and time of activity-based sensing. We develop photocaged activity-based sensors by conjugating photolabile molecules directly onto peptide substrates, thereby blocking protease cleavage by steric hindrance. At sites of disease, exposure to ultraviolet light unveils the nanosensors to allow proteases to cleave and release a reporter fragment that can be detected remotely. We apply this spatiotemporally controlled system to probe secreted protease activity in vitro and tumor protease activity in vivo. In vitro, we demonstrate the ability to dynamically and spatially measure metalloproteinase activity in a 3D model of colorectal cancer. In vivo, veiled nanosensors are selectively activated at the primary tumor site in colorectal cancer xenografts to capture the tumor microenvironment-enriched protease activity. The ability to remotely control activity-based sensors may offer a valuable complement to existing tools for measuring biological activity.

  18. Spatiotemporal characteristics of electrocortical brain activity during mental calculation.

    PubMed

    Vansteensel, Mariska J; Bleichner, Martin G; Freudenburg, Zac V; Hermes, Dora; Aarnoutse, Erik J; Leijten, Frans S S; Ferrier, Cyrille H; Jansma, Johan Martijn; Ramsey, Nick F

    2014-12-01

    Mental calculation is a complex mental procedure involving a frontoparietal network of brain regions. Functional MRI (fMRI) studies have revealed interesting characteristics of these regions, but the precise function of some areas remains elusive. In the present study, we used electrocorticographic (ECoG) recordings to chronometrically assess the neuronal processes during mental arithmetic. A calculation task was performed during presurgical 3T fMRI scanning and subsequent ECoG monitoring. Mental calculation induced an increase in fMRI blood oxygen level dependent signal in prefrontal, parietal and lower temporo-occipital regions. The group-fMRI result was subsequently used to cluster the implanted electrodes into anatomically defined regions of interest (ROIs). We observed remarkable differences in high frequency power profiles between ROIs, some of which were closely associated with stimulus presentation and others with the response. Upon stimulus presentation, occipital areas were the first to respond, followed by parietal and frontal areas, and finally by motor areas. Notably, we demonstrate that the fMRI activation in the middle frontal gyrus/precentral gyrus is associated with two subfunctions during mental calculation. This finding reveals the significance of the temporal dynamics of neural ensembles within regions with an apparent uniform function. In conclusion, our results shed more light on the spatiotemporal aspects of brain activation during a mental calculation task, and demonstrate that the use of fMRI data to cluster ECoG electrodes is a useful approach for ECoG group analysis.

  19. Spatiotemporal dynamics of large-scale brain activity

    NASA Astrophysics Data System (ADS)

    Neuman, Jeremy

    Understanding the dynamics of large-scale brain activity is a tough challenge. One reason for this is the presence of an incredible amount of complexity arising from having roughly 100 billion neurons connected via 100 trillion synapses. Because of the extremely high number of degrees of freedom in the nervous system, the question of how the brain manages to properly function and remain stable, yet also be adaptable, must be posed. Neuroscientists have identified many ways the nervous system makes this possible, of which synaptic plasticity is possibly the most notable one. On the other hand, it is vital to understand how the nervous system also loses stability, resulting in neuropathological diseases such as epilepsy, a disease which affects 1% of the population. In the following work, we seek to answer some of these questions from two different perspectives. The first uses mean-field theory applied to neuronal populations, where the variables of interest are the percentages of active excitatory and inhibitory neurons in a network, to consider how the nervous system responds to external stimuli, self-organizes and generates epileptiform activity. The second method uses statistical field theory, in the framework of single neurons on a lattice, to study the concept of criticality, an idea borrowed from physics which posits that in some regime the brain operates in a collectively stable or marginally stable manner. This will be examined in two different neuronal networks with self-organized criticality serving as the overarching theme for the union of both perspectives. One of the biggest problems in neuroscience is the question of to what extent certain details are significant to the functioning of the brain. These details give rise to various spatiotemporal properties that at the smallest of scales explain the interaction of single neurons and synapses and at the largest of scales describe, for example, behaviors and sensations. In what follows, we will shed some

  20. The brain's spontaneous activity and its psychopathological symptoms - "Spatiotemporal binding and integration".

    PubMed

    Northoff, Georg

    2017-03-28

    Neuroimaging provided much insight into the neural activity of the brain and its alterations in psychiatric disorders. However, despite extensive research, the exact neuronal mechanisms leading to the various psychopathological symptoms remain unclear, yet. In addition to task-evoked activity during affective, cognitive, or other challenges, the brain's spontaneous or resting state activity has come increasingly into the focus. Basically all psychiatric disorders show abnormal resting state activity with the relation to psychopathological symptoms remaining unclear though. I here suggest to conceive the brain's spontaneous activity in spatiotemporal terms that is, by various mechanisms that are based on its spatial, i.e., functional connectivity, and temporal, i.e., fluctuations in different frequencies, features. I here point out two such spatiotemporal mechanisms, i.e., "spatiotemporal binding and integration". Alterations in the resting state's spatial and temporal features lead to abnormal "spatiotemporal binding and integration" which results in abnormal contents in cognition as in the various psychopathological symptoms. This, together with concrete empirical evidence, is demonstrated in depression and schizophrenia. I therefore conclude that we need to develop a spatiotemporal approach to psychopathology, "spatiotemporal psychopathology:" as I call it.

  1. Activity induces traveling waves, vortices and spatiotemporal chaos in a model actomyosin layer

    PubMed Central

    Ramaswamy, Rajesh; Jülicher, Frank

    2016-01-01

    Inspired by the actomyosin cortex in biological cells, we investigate the spatiotemporal dynamics of a model describing a contractile active polar fluid sandwiched between two external media. The external media impose frictional forces at the interface with the active fluid. The fluid is driven by a spatially-homogeneous activity measuring the strength of the active stress that is generated by processes consuming a chemical fuel. We observe that as the activity is increased over two orders of magnitude the active polar fluid first shows spontaneous flow transition followed by transition to oscillatory dynamics with traveling waves and traveling vortices in the flow field. In the flow-tumbling regime, the active polar fluid also shows transition to spatiotemporal chaos at sufficiently large activities. These results demonstrate that level of activity alone can be used to tune the operating point of actomyosin layers with qualitatively different spatiotemporal dynamics. PMID:26877263

  2. Changes in direction-specific activity of psoas major and quadratus lumborum in people with recurring back pain differ between muscle regions and patient groups.

    PubMed

    Park, Rachel J; Tsao, Henry; Cresswell, Andrew G; Hodges, Paul W

    2013-06-01

    Psoas major (PM) and quadratus lumborum (QL) muscles have anatomically discrete regions. Redistribution of activity between these regions has been observed in people with low back pain (LBP). We hypothesised that the bias of activity of specific regions of PM and QL towards trunk extension may change depending on whether LBP individuals have more or less erector spinae (ES) activity in an extended/upright lumbar posture. Ten volunteers with recurring episodes of LBP and nine pain-free controls performed isometric trunk efforts in upright sitting. LBP individuals were subgrouped into those with high and low ES electromyographic activity (EMG) when sitting with a lumbar lordosis. Fine-wire electrodes were inserted into fascicles of PM arising from the transverse process (PM-t) and vertebral body (PM-v) and anterior (QL-a) and posterior layers (QL-p) of QL. The LBP group with low ES EMG had greater bias of PM-t, PM-v and QL-p towards trunk extension. The LBP group with high ES activity showed less PM activity towards extension. These findings suggest redistribution of activity within and/or between these muscles with extensor moments. This is likely to be important to consider for effective clinical interventions for individuals with LBP.

  3. Activity Changes Induced by Spatio-Temporally Correlated Stimuli in Cultured Cortical Networks

    NASA Astrophysics Data System (ADS)

    Takayama, Yuzo; Moriguchi, Hiroyuki; Jimbo, Yasuhiko

    Activity-dependent plasticity probably plays a key role in learning and memory in biological information processing systems. Though long-term potentiation and depression have been extensively studied in the filed of neuroscience, little is known on the mechanisms for integrating these modifications on network-wide activity changes. In this report, we studied effects of spatio-temporally correlated stimuli on the neuronal network activity. Rat cortical neurons were cultured on substrates with 64 embedded micro-electrodes and the evoked responses were extracellularly recorded and analyzed. We compared spatio-temporal patterns of the responses between before and after repetitive application of correlated stimuli. After the correlated stimuli, the networks showed significantly different responses from those in the initial states. The modified activity reflected structures of the repeatedly applied correlated stimuli. The results suggested that spatiotemporally correlated inputs systematically induced modification of synaptic strengths in neuronal networks, which could serve as an underlying mechanism of associative memory.

  4. Controlling Spatiotemporal Chaos in Active Dissipative-Dispersive Nonlinear Systems

    NASA Astrophysics Data System (ADS)

    Gomes, Susana; Pradas, Marc; Kalliadasis, Serafim; Papageorgiou, Demetrios; Pavliotis, Grigorios

    2015-11-01

    We present a novel generic methodology for the stabilization and control of infinite-dimensional dynamical systems exhibiting low-dimensional spatiotemporal chaos. The methodology is exemplified with the generalized Kuramoto-Sivashinsky equation, the simplest possible prototype that retains that fundamental elements of any nonlinear process involving wave evolution. The equation is applicable on a wide variety of systems including falling liquid films and plasma waves with dispersion due to finite banana width. We show that applying the appropriate choice of time-dependent feedback controls via blowing and suction, we are able to stabilize and/or control all stable or unstable solutions, including steady solutions, travelling waves and spatiotemporal chaos, but also use the controls obtained to stabilize the solutions to more general long wave models. We acknowledge financial support from Imperial College through a Roth PhD studentship, Engineering and Physical Sciences Research Council of the UK through Grants No. EP/H034587, EP/J009636, EP/K041134, EP/L020564 and EP/L024926 and European Research Council via Advanced Grant No. 247031.

  5. Robust segmentation of moving objects in video based on spatiotemporal visual saliency and active contour model

    NASA Astrophysics Data System (ADS)

    Ramadan, Hiba; Tairi, Hamid

    2016-11-01

    This paper presents an algorithm for automatic segmentation of moving objects in video based on spatiotemporal visual saliency and an active contour model. Our algorithm exploits the visual saliency and motion information to build a spatiotemporal visual saliency map used to extract a moving region of interest. This region is used to automatically provide the seeds for the convex active contour (CAC) model to segment the moving object accurately. The experiments show a good performance of our algorithm for moving object segmentation in video without user interaction, especially on the SegTrack dataset.

  6. Spatiotemporal Analysis of a Glycolytic Activity Gradient Linked to Mouse Embryo Mesoderm Development.

    PubMed

    Bulusu, Vinay; Prior, Nicole; Snaebjornsson, Marteinn T; Kuehne, Andreas; Sonnen, Katharina F; Kress, Jana; Stein, Frank; Schultz, Carsten; Sauer, Uwe; Aulehla, Alexander

    2017-02-27

    How metabolism is rewired during embryonic development is still largely unknown, as it remains a major technical challenge to resolve metabolic activities or metabolite levels with spatiotemporal resolution. Here, we investigated metabolic changes during development of organogenesis-stage mouse embryos, focusing on the presomitic mesoderm (PSM). We measured glycolytic labeling kinetics from (13)C-glucose tracing experiments and detected elevated glycolysis in the posterior, more undifferentiated PSM. We found evidence that the spatial metabolic differences are functionally relevant during PSM development. To enable real-time quantification of a glycolytic metabolite with spatiotemporal resolution, we generated a pyruvate FRET-sensor reporter mouse line. We revealed dynamic changes in cytosolic pyruvate levels as cells transit toward a more anterior PSM state. Combined, our approach identifies a gradient of glycolytic activity across the PSM, and we provide evidence that these spatiotemporal metabolic changes are intrinsically linked to PSM development and differentiation.

  7. Brain Network Activation Analysis Utilizing Spatiotemporal Features for Event Related Potentials Classification

    PubMed Central

    Stern, Yaki; Reches, Amit; Geva, Amir B.

    2016-01-01

    The purpose of this study was to introduce an improved tool for automated classification of event-related potentials (ERPs) using spatiotemporally parcellated events incorporated into a functional brain network activation (BNA) analysis. The auditory oddball ERP paradigm was selected to demonstrate and evaluate the improved tool. Methods: The ERPs of each subject were decomposed into major dynamic spatiotemporal events. Then, a set of spatiotemporal events representing the group was generated by aligning and clustering the spatiotemporal events of all individual subjects. The temporal relationship between the common group events generated a network, which is the spatiotemporal reference BNA model. Scores were derived by comparing each subject's spatiotemporal events to the reference BNA model and were then entered into a support vector machine classifier to classify subjects into relevant subgroups. The reliability of the BNA scores (test-retest repeatability using intraclass correlation) and their utility as a classification tool were examined in the context of Target-Novel classification. Results: BNA intraclass correlation values of repeatability ranged between 0.51 and 0.82 for the known ERP components N100, P200, and P300. Classification accuracy was high when the trained data were validated on the same subjects for different visits (AUCs 0.93 and 0.95). The classification accuracy remained high for a test group recorded at a different clinical center with a different recording system (AUCs 0.81, 0.85 for 2 visits). Conclusion: The improved spatiotemporal BNA analysis demonstrates high classification accuracy. The BNA analysis method holds promise as a tool for diagnosis, follow-up and drug development associated with different neurological conditions. PMID:28066224

  8. Spatiotemporal patterns of acoustic emission (AE) activity in salt mine

    NASA Astrophysics Data System (ADS)

    Maghsoudi, S.; Cesca, S.; Hainzl, S.; Kaiser, D.; Dahm, T.

    2012-04-01

    Assessing the magnitude of completeness (Mc) is essential for the correct interpretation of earthquake catalogs. Knowledge on the spatiotemporal variation of Mc allows the mapping of other seismicity parameters, such as b-values. Spatial and temporal variations of b-values can indicate structural heterogeneities, stress perturbations and time-dependent fracturing processes. In order to precisely estimate Mc in strongly heterogeneous media, we propose a 3D development of the probabilistic magnitude of completeness (PMC) method, which relies on the analysis of network detection capabilities, to study spatial distribution of the Mc and b-value estimations for mining networks. We used a large dataset including more than 1 million acoustic emissions (AE), recorded at the Morsleben salt mine, Germany. Our study shows that the PMC estimations strongly depend on the source-receiver direction, and cannot be correctly accounted using a standard approach. The comparison between Mc using the 3D PMC method and Gutenberg-Richter methods show agreements for two reference depth ranges. Following our approach, we estimate Mc ranging between 1.25 (AE ,relative acoustic magnitude), at the center of the network, and 3.5, at further distances outside the network. Our method provides small-scale details about the capability of sensors to detect an AE event, and spatial distributions of Mc and b-value, which can be linked to the presence of structural heterogeneities or cavities in specific directions. Effects of heterogeneities on detection analysis are confirmed by synthetic tests using waveform modeling in heterogeneous media. This work has been funded by the German BMBF "Geotechnologien" project MINE (BMBF03G0737A).

  9. Supervised learning for neural manifold using spatiotemporal brain activity

    NASA Astrophysics Data System (ADS)

    Kuo, Po-Chih; Chen, Yong-Sheng; Chen, Li-Fen

    2015-12-01

    Objective. Determining the means by which perceived stimuli are compactly represented in the human brain is a difficult task. This study aimed to develop techniques for the construction of the neural manifold as a representation of visual stimuli. Approach. We propose a supervised locally linear embedding method to construct the embedded manifold from brain activity, taking into account similarities between corresponding stimuli. In our experiments, photographic portraits were used as visual stimuli and brain activity was calculated from magnetoencephalographic data using a source localization method. Main results. The results of 10 × 10-fold cross-validation revealed a strong correlation between manifolds of brain activity and the orientation of faces in the presented images, suggesting that high-level information related to image content can be revealed in the brain responses represented in the manifold. Significance. Our experiments demonstrate that the proposed method is applicable to investigation into the inherent patterns of brain activity.

  10. Synaptic background activity influences spatiotemporal integration in single pyramidal cells.

    PubMed Central

    Bernander, O; Douglas, R J; Martin, K A; Koch, C

    1991-01-01

    The standard one-dimensional Rall cable model assumes that the electrotonic structure of neurons does not change in response to synaptic input. This model is used in a great number of both theoretical and anatomical-physiological structure-function studies. In particular, the membrane time constant, tau m, the somatic input resistance, Rin, and the electrotonic length are used to characterize single cells. However, these studies do not take into account that neurons are embedded in a network of spontaneously active cells. Synapses from these cells will contribute significantly to the membrane conductance, especially if recent evidence of very high specific membrane resistance, Rm = 100 k omega.cm2, is taken into account. We numerically simulated the electrical behavior of an anatomically reconstructed layer V cortical pyramidal cell receiving input from 4000 excitatory and 1000 inhibitory cells firing spontaneously at 0-7 Hz. We found that, over this range of synaptic background activity, tau m and Rin change by a factor of 10 (80-7 msec, 110-14 M omega) and the electrotonic length of the cell changes by a factor of 3. We show that this significantly changes the response of the cell to temporal desynchronized versus temporal synchronized synaptic input distributed throughout the neuron. Thus, the global activity of the network can control how individual cells perform spatial and temporal integration. PMID:1763072

  11. Optogenetically induced spatiotemporal gamma oscillations and neuronal spiking activity in primate motor cortex

    PubMed Central

    Lu, Yao; Truccolo, Wilson; Wagner, Fabien B.; Vargas-Irwin, Carlos E.; Ozden, Ilker; Zimmermann, Jonas B.; May, Travis; Agha, Naubahar S.; Wang, Jing

    2015-01-01

    Transient gamma-band (40–80 Hz) spatiotemporal patterns are hypothesized to play important roles in cortical function. Here we report the direct observation of gamma oscillations as spatiotemporal waves induced by targeted optogenetic stimulation, recorded by intracortical multichannel extracellular techniques in macaque monkeys during their awake resting states. Microelectrode arrays integrating an optical fiber at their center were chronically implanted in primary motor (M1) and ventral premotor (PMv) cortices of two subjects. Targeted brain tissue was transduced with the red-shifted opsin C1V1(T/T). Constant (1-s square pulses) and ramp stimulation induced narrowband gamma oscillations during awake resting states. Recordings across 95 microelectrodes (4 × 4-mm array) enabled us to track the transient gamma spatiotemporal patterns manifested, e.g., as concentric expanding and spiral waves. Gamma oscillations were induced well beyond the light stimulation volume, via network interactions at distal electrode sites, depending on optical power. Despite stimulation-related modulation in spiking rates, neuronal spiking remained highly asynchronous during induced gamma oscillations. In one subject we examined stimulation effects during preparation and execution of a motor task and observed that movement execution largely attenuated optically induced gamma oscillations. Our findings demonstrate that, beyond previously reported induced gamma activity under periodic drive, a prolonged constant stimulus above a certain threshold may carry primate motor cortex network dynamics into gamma oscillations, likely via a Hopf bifurcation. More broadly, the experimental capability in combining microelectrode array recordings and optogenetic stimulation provides an important approach for probing spatiotemporal dynamics in primate cortical networks during various physiological and behavioral conditions. PMID:25761956

  12. Optogenetically induced spatiotemporal gamma oscillations and neuronal spiking activity in primate motor cortex.

    PubMed

    Lu, Yao; Truccolo, Wilson; Wagner, Fabien B; Vargas-Irwin, Carlos E; Ozden, Ilker; Zimmermann, Jonas B; May, Travis; Agha, Naubahar S; Wang, Jing; Nurmikko, Arto V

    2015-06-01

    Transient gamma-band (40-80 Hz) spatiotemporal patterns are hypothesized to play important roles in cortical function. Here we report the direct observation of gamma oscillations as spatiotemporal waves induced by targeted optogenetic stimulation, recorded by intracortical multichannel extracellular techniques in macaque monkeys during their awake resting states. Microelectrode arrays integrating an optical fiber at their center were chronically implanted in primary motor (M1) and ventral premotor (PMv) cortices of two subjects. Targeted brain tissue was transduced with the red-shifted opsin C1V1(T/T). Constant (1-s square pulses) and ramp stimulation induced narrowband gamma oscillations during awake resting states. Recordings across 95 microelectrodes (4 × 4-mm array) enabled us to track the transient gamma spatiotemporal patterns manifested, e.g., as concentric expanding and spiral waves. Gamma oscillations were induced well beyond the light stimulation volume, via network interactions at distal electrode sites, depending on optical power. Despite stimulation-related modulation in spiking rates, neuronal spiking remained highly asynchronous during induced gamma oscillations. In one subject we examined stimulation effects during preparation and execution of a motor task and observed that movement execution largely attenuated optically induced gamma oscillations. Our findings demonstrate that, beyond previously reported induced gamma activity under periodic drive, a prolonged constant stimulus above a certain threshold may carry primate motor cortex network dynamics into gamma oscillations, likely via a Hopf bifurcation. More broadly, the experimental capability in combining microelectrode array recordings and optogenetic stimulation provides an important approach for probing spatiotemporal dynamics in primate cortical networks during various physiological and behavioral conditions.

  13. Spatiotemporal relations of primary sensorimotor and secondary motor activation patterns mapped by NIR imaging

    PubMed Central

    Khan, Bilal; Chand, Pankaj; Alexandrakis, George

    2011-01-01

    Functional near infrared (fNIR) imaging was used to identify spatiotemporal relations between spatially distinct cortical regions activated during various hand and arm motion protocols. Imaging was performed over a field of view (FOV, 12 x 8.4 cm) including the secondary motor, primary sensorimotor, and the posterior parietal cortices over a single brain hemisphere. This is a more extended FOV than typically used in current fNIR studies. Three subjects performed four motor tasks that induced activation over this extended FOV. The tasks included card flipping (pronation and supination) that, to our knowledge, has not been performed in previous functional magnetic resonance imaging (fMRI) or fNIR studies. An earlier rise and a longer duration of the hemodynamic activation response were found in tasks requiring increased physical or mental effort. Additionally, analysis of activation images by cluster component analysis (CCA) demonstrated that cortical regions can be grouped into clusters, which can be adjacent or distant from each other, that have similar temporal activation patterns depending on whether the performed motor task is guided by visual or tactile feedback. These analyses highlight the future potential of fNIR imaging to tackle clinically relevant questions regarding the spatiotemporal relations between different sensorimotor cortex regions, e.g. ones involved in the rehabilitation response to motor impairments. PMID:22162826

  14. Spatiotemporal analysis of RhoA/B/C activation in primary human endothelial cells

    PubMed Central

    Reinhard, Nathalie R.; van Helden, Suzanne F.; Anthony, Eloise C.; Yin, Taofei; Wu, Yi I.; Goedhart, Joachim; Gadella, Theodorus W. J.; Hordijk, Peter L.

    2016-01-01

    Endothelial cells line the vasculature and are important for the regulation of blood pressure, vascular permeability, clotting and transendothelial migration of leukocytes and tumor cells. A group of proteins that that control the endothelial barrier function are the RhoGTPases. This study focuses on three homologous (>88%) RhoGTPases: RhoA, RhoB, RhoC of which RhoB and RhoC have been poorly characterized. Using a RhoGTPase mRNA expression analysis we identified RhoC as the highest expressed in primary human endothelial cells. Based on an existing RhoA FRET sensor we developed new RhoB/C FRET sensors to characterize their spatiotemporal activation properties. We found all these RhoGTPase sensors to respond to physiologically relevant agonists (e.g. Thrombin), reaching transient, localized FRET ratio changes up to 200%. These RhoA/B/C FRET sensors show localized GEF and GAP activity and reveal spatial activation differences between RhoA/C and RhoB. Finally, we used these sensors to monitor GEF-specific differential activation of RhoA/B/C. In summary, this study adds high-contrast RhoB/C FRET sensors to the currently available FRET sensor toolkit and uncover new insights in endothelial and RhoGTPase cell biology. This allows us to study activation and signaling by these closely related RhoGTPases with high spatiotemporal resolution in primary human cells. PMID:27147504

  15. Sensitivity of cochlear nucleus neurons to spatio-temporal changes in auditory nerve activity

    PubMed Central

    Wang, Grace I.

    2012-01-01

    The spatio-temporal pattern of auditory nerve (AN) activity, representing the relative timing of spikes across the tonotopic axis, contains cues to perceptual features of sounds such as pitch, loudness, timbre, and spatial location. These spatio-temporal cues may be extracted by neurons in the cochlear nucleus (CN) that are sensitive to relative timing of inputs from AN fibers innervating different cochlear regions. One possible mechanism for this extraction is “cross-frequency” coincidence detection (CD), in which a central neuron converts the degree of coincidence across the tonotopic axis into a rate code by preferentially firing when its AN inputs discharge in synchrony. We used Huffman stimuli (Carney LH. J Neurophysiol 64: 437–456, 1990), which have a flat power spectrum but differ in their phase spectra, to systematically manipulate relative timing of spikes across tonotopically neighboring AN fibers without changing overall firing rates. We compared responses of CN units to Huffman stimuli with responses of model CD cells operating on spatio-temporal patterns of AN activity derived from measured responses of AN fibers with the principle of cochlear scaling invariance. We used the maximum likelihood method to determine the CD model cell parameters most likely to produce the measured CN unit responses, and thereby could distinguish units behaving like cross-frequency CD cells from those consistent with same-frequency CD (in which all inputs would originate from the same tonotopic location). We find that certain CN unit types, especially those associated with globular bushy cells, have responses consistent with cross-frequency CD cells. A possible functional role of a cross-frequency CD mechanism in these CN units is to increase the dynamic range of binaural neurons that process cues for sound localization. PMID:22972956

  16. Recurring slope lineae in equatorial regions of Mars

    USGS Publications Warehouse

    McEwen, Alfred S.; Dundas, Colin M.; Mattson, Sarah S.; Toigo, Anthony D.; Ojha, Lujendra; Wray, James J.; Chojnacki, Matthew; Byrne, Shane; Murchie, Scott L.; Thomas, Nicolas

    2014-01-01

    The presence of liquid water is a requirement of habitability on a planet. Possible indicators of liquid surface water on Mars include intermittent flow-like features observed on sloping terrains. These recurring slope lineae are narrow, dark markings on steep slopes that appear and incrementally lengthen during warm seasons on low-albedo surfaces. The lineae fade in cooler seasons and recur over multiple Mars years. Recurring slope lineae were initially reported to appear and lengthen at mid-latitudes in the late southern spring and summer and are more common on equator-facing slopes where and when the peak surface temperatures are higher. Here we report extensive activity of recurring slope lineae in equatorial regions of Mars, particularly in the deep canyons of Valles Marineris, from analysis of data acquired by the Mars Reconnaissance Orbiter. We observe the lineae to be most active in seasons when the slopes often face the sun. Expected peak temperatures suggest that activity may not depend solely on temperature. Although the origin of the recurring slope lineae remains an open question, our observations are consistent with intermittent flow of briny water. Such an origin suggests surprisingly abundant liquid water in some near-surface equatorial regions of Mars.

  17. Taxis of Artificial Swimmers in a Spatio-Temporally Modulated Activation Medium

    NASA Astrophysics Data System (ADS)

    Geiseler, Alexander; Hänggi, Peter; Marchesoni, Fabio

    2017-03-01

    Contrary to microbial taxis, where a tactic response to external stimuli is controlled by complex chemical pathways acting like sensor-actuator loops, taxis of artificial microswimmers is a purely stochastic effect associated with a non-uniform activation of the particles' self-propulsion. We study the tactic response of such swimmers in a spatio-temporally modulated activating medium by means of both numerical and analytical techniques. In the opposite limits of very fast and very slow rotational particle dynamics, we obtain analytic approximations that closely reproduce the numerical description. A swimmer drifts on average either parallel or anti-parallel to the propagation direction of the activating pulses, depending on their speed and width. The drift in line with the pulses is solely determined by the finite persistence length of the active Brownian motion performed by the swimmer, whereas the drift in the opposite direction results from the combination of ballistic and diffusive properties of the swimmer's dynamics.

  18. Parallel optical control of spatiotemporal neuronal spike activity using high-speed digital light processing.

    PubMed

    Jerome, Jason; Foehring, Robert C; Armstrong, William E; Spain, William J; Heck, Detlef H

    2011-01-01

    Neurons in the mammalian neocortex receive inputs from and communicate back to thousands of other neurons, creating complex spatiotemporal activity patterns. The experimental investigation of these parallel dynamic interactions has been limited due to the technical challenges of monitoring or manipulating neuronal activity at that level of complexity. Here we describe a new massively parallel photostimulation system that can be used to control action potential firing in in vitro brain slices with high spatial and temporal resolution while performing extracellular or intracellular electrophysiological measurements. The system uses digital light processing technology to generate 2-dimensional (2D) stimulus patterns with >780,000 independently controlled photostimulation sites that operate at high spatial (5.4 μm) and temporal (>13 kHz) resolution. Light is projected through the quartz-glass bottom of the perfusion chamber providing access to a large area (2.76 mm × 2.07 mm) of the slice preparation. This system has the unique capability to induce temporally precise action potential firing in large groups of neurons distributed over a wide area covering several cortical columns. Parallel photostimulation opens up new opportunities for the in vitro experimental investigation of spatiotemporal neuronal interactions at a broad range of anatomical scales.

  19. Parallel Optical Control of Spatiotemporal Neuronal Spike Activity Using High-Speed Digital Light Processing

    PubMed Central

    Jerome, Jason; Foehring, Robert C.; Armstrong, William E.; Spain, William J.; Heck, Detlef H.

    2011-01-01

    Neurons in the mammalian neocortex receive inputs from and communicate back to thousands of other neurons, creating complex spatiotemporal activity patterns. The experimental investigation of these parallel dynamic interactions has been limited due to the technical challenges of monitoring or manipulating neuronal activity at that level of complexity. Here we describe a new massively parallel photostimulation system that can be used to control action potential firing in in vitro brain slices with high spatial and temporal resolution while performing extracellular or intracellular electrophysiological measurements. The system uses digital light processing technology to generate 2-dimensional (2D) stimulus patterns with >780,000 independently controlled photostimulation sites that operate at high spatial (5.4 μm) and temporal (>13 kHz) resolution. Light is projected through the quartz–glass bottom of the perfusion chamber providing access to a large area (2.76 mm × 2.07 mm) of the slice preparation. This system has the unique capability to induce temporally precise action potential firing in large groups of neurons distributed over a wide area covering several cortical columns. Parallel photostimulation opens up new opportunities for the in vitro experimental investigation of spatiotemporal neuronal interactions at a broad range of anatomical scales. PMID:21904526

  20. Spatiotemporal regulation of chemical reaction kinetics of cell surface molecules by active remodeling of cortical actin

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Bhaswati; Chaudhuri, Abhishek; Gowrishankar, Kripa; Mayor, Satyajit; Rao, Madan

    2010-03-01

    Cell surface proteins such as lipid tethered GPI-anchored proteins and Ras-proteins are distributed as monomers and nanoclusters on the surface of living cells. Recent work from our laboratory suggests that the spatial distribution and dynamics of formation and breakup of these nanoclusters is controlled by the active remodeling dynamics of the underlying cortical actin. To explain these observations, we propose a novel mechanism of nanoclustering, involving the transient binding to and advection along constitutively occuring ``asters'' of cortical actin. Here we study the consequences of such active actin based clustering, in the context of chemical reactions involving conformational changes of cell surface proteins. We find that active remodeling of cortical actin, can give rise to a dramatic increase in the reaction efficiency and output levels. In general, such actin driven clustering of membrane proteins could be a cellular mechanism to spatiotemporally regulate and amplify local chemical reaction rates, in the context of signalling and endocytosis.

  1. Reconstruction of Neural Activity from EEG Data Using Dynamic Spatiotemporal Constraints.

    PubMed

    Giraldo-Suarez, E; Martinez-Vargas, J D; Castellanos-Dominguez, G

    2016-11-01

    We present a novel iterative regularized algorithm (IRA) for neural activity reconstruction that explicitly includes spatiotemporal constraints, performing a trade-off between space and time resolutions. For improving the spatial accuracy provided by electroencephalography (EEG) signals, we explore a basis set that describes the smooth, localized areas of potentially active brain regions. In turn, we enhance the time resolution by adding the Markovian assumption for brain activity estimation at each time period. Moreover, to deal with applications that have either distributed or localized neural activity, the spatiotemporal constraints are expressed through [Formula: see text] and [Formula: see text] norms, respectively. For the purpose of validation, we estimate the neural reconstruction performance in time and space separately. Experimental testing is carried out on artificial data, simulating stationary and non-stationary EEG signals. Also, validation is accomplished on two real-world databases, one holding Evoked Potentials and another with EEG data of focal epilepsy. Moreover, responses of functional magnetic resonance imaging for the former EEG data have been measured in advance, allowing to contrast our findings. Obtained results show that the [Formula: see text]-based IRA produces a spatial resolution that is comparable to the one achieved by some widely used sparse-based estimators of brain activity. At the same time, the [Formula: see text]-based IRA outperforms other similar smooth solutions, providing a spatial resolution that is lower than the sparse [Formula: see text]-based solution. As a result, the proposed IRA is a promising method for improving the accuracy of brain activity reconstruction.

  2. Characterization of orderly spatiotemporal patterns of clock gene activation in mammalian suprachiasmatic nucleus

    PubMed Central

    Foley, Nicholas C.; Tong, Tina Y.; Foley, Duncan; LeSauter, Joseph; Welsh, David K.

    2012-01-01

    Because we can observe oscillation within individual cells and in the tissue as a whole, the suprachiasmatic nucleus (SCN) presents a unique system in the mammalian brain for the analysis of individual cells and the networks of which they are a part. While dispersed cells of the SCN sustain circadian oscillations in isolation, they are unstable oscillators that require network interactions for robust cycling. Using cluster analysis to assess bioluminescence in acute brain slices from PERIOD2∷Luciferase (PER2∷LUC) knockin mice, and immunochemistry of SCN from animals harvested at various circadian times, we assessed the spatiotemporal activation patterns of PER2 to explore the emergence of a coherent oscillation at the tissue level. The results indicate that circadian oscillation is characterized by a stable daily cycle of PER2 expression involving orderly serial activation of specific SCN subregions, followed by a silent interval, with substantial symmetry between the left and right side of the SCN. The biological significance of the clusters identified in living slices was confirmed by co-expression of LUC and PER2 in fixed, immunochemically stained brain sections, with the spatiotemporal pattern of LUC expression resembling that revealed in the cluster analysis of bioluminescent slices. We conclude that the precise timing of PER2 expression within individual neurons is dependent on their location within the nucleus, and that small groups of neurons within the SCN give rise to distinctive and identifiable subregions. We propose that serial activation of these subregions is the basis of robustness and resilience of the daily rhythm of the SCN. PMID:21488990

  3. Spatio-temporal expression of peroxisome proliferator-activated receptor α during human prenatal development.

    PubMed

    Cizkova, Katerina; Rajdova, Aneta; Ehrmann, Jiri

    2015-04-01

    Peroxisome proliferator-activated receptor α (PPARα) is a ligand-dependent transcription factor which is activated by various endogenous as well as exogenous compounds. It is involved in the regulation of a variety of biological processes, such as nutrient metabolism, energy homoeostasis, immunological response and xenobiotic metabolism. Little is known about its expression during human prenatal development. We examined the spatio-temporal expression pattern of PPARα in human embryonic/foetal intestines, liver and kidney from the 5th to 20th week of prenatal life by indirect two-step immunohistochemistry. PPARα expression can already be detected in the early stages of prenatal development; as early as the 7th week of intrauterine development (IUD) in the intestines, 5th week of IUD in the liver and 6th week of IUD in the kidney. We found age-dependent changes in the PPARα expression pattern in the intestines and kidney. These events occur approximately at the commencement of function of these organs. In the intestines, we detected an obvious change of the PPARα expression pattern along the crypt-villous axis in the 11th week of IUD. In the kidney, the most apparent change was increased expression of PPARα in glomeruli in the 12th week of IUD. Moreover, in the liver, we detected a strong positivity in part of the developing blood elements. Information about the spatio-temporal expression pattern of PPARα could be the first step in evaluating the potential harmful impact of a wide range of environmental or pharmaceutical compounds which serve as PPARα ligands on the developing human organism.

  4. Imaging the spatiotemporal organization of neural activity in the developing spinal cord.

    PubMed

    O'Donovan, Michael J; Bonnot, Agnes; Mentis, George Z; Arai, Yoshi; Chub, Nikolai; Shneider, Neil A; Wenner, Peter

    2008-05-01

    In this review, we discuss the use of imaging to visualize the spatiotemporal organization of network activity in the developing spinal cord of the chick embryo and the neonatal mouse. We describe several different methods for loading ion- and voltage-sensitive dyes into spinal neurons and consider the advantages and limitations of each one. We review work in the chick embryo, suggesting that motoneurons play a critical role in the initiation of each cycle of spontaneous network activity and describe how imaging has been used to identify a class of spinal interneuron that appears to be the avian homolog of mammalian Renshaw cells or 1a-inhibitory interneurons. Imaging of locomotor-like activity in the neonatal mouse revealed a wave-like activation of motoneurons during each cycle of discharge. We discuss the significance of this finding and its implications for understanding how locomotor-like activity is coordinated across different segments of the cord. In the last part of the review, we discuss some of the exciting new prospects for the future.

  5. Resting-state hemodynamics are spatiotemporally coupled to synchronized and symmetric neural activity in excitatory neurons

    PubMed Central

    Ma, Ying; Shaik, Mohammed A.; Kozberg, Mariel G.; Portes, Jacob P.; Timerman, Dmitriy

    2016-01-01

    Brain hemodynamics serve as a proxy for neural activity in a range of noninvasive neuroimaging techniques including functional magnetic resonance imaging (fMRI). In resting-state fMRI, hemodynamic fluctuations have been found to exhibit patterns of bilateral synchrony, with correlated regions inferred to have functional connectivity. However, the relationship between resting-state hemodynamics and underlying neural activity has not been well established, making the neural underpinnings of functional connectivity networks unclear. In this study, neural activity and hemodynamics were recorded simultaneously over the bilateral cortex of awake and anesthetized Thy1-GCaMP mice using wide-field optical mapping. Neural activity was visualized via selective expression of the calcium-sensitive fluorophore GCaMP in layer 2/3 and 5 excitatory neurons. Characteristic patterns of resting-state hemodynamics were accompanied by more rapidly changing bilateral patterns of resting-state neural activity. Spatiotemporal hemodynamics could be modeled by convolving this neural activity with hemodynamic response functions derived through both deconvolution and gamma-variate fitting. Simultaneous imaging and electrophysiology confirmed that Thy1-GCaMP signals are well-predicted by multiunit activity. Neurovascular coupling between resting-state neural activity and hemodynamics was robust and fast in awake animals, whereas coupling in urethane-anesthetized animals was slower, and in some cases included lower-frequency (<0.04 Hz) hemodynamic fluctuations that were not well-predicted by local Thy1-GCaMP recordings. These results support that resting-state hemodynamics in the awake and anesthetized brain are coupled to underlying patterns of excitatory neural activity. The patterns of bilaterally-symmetric spontaneous neural activity revealed by wide-field Thy1-GCaMP imaging may depict the neural foundation of functional connectivity networks detected in resting-state fMRI. PMID:27974609

  6. Resting-state hemodynamics are spatiotemporally coupled to synchronized and symmetric neural activity in excitatory neurons.

    PubMed

    Ma, Ying; Shaik, Mohammed A; Kozberg, Mariel G; Kim, Sharon H; Portes, Jacob P; Timerman, Dmitriy; Hillman, Elizabeth M C

    2016-12-27

    Brain hemodynamics serve as a proxy for neural activity in a range of noninvasive neuroimaging techniques including functional magnetic resonance imaging (fMRI). In resting-state fMRI, hemodynamic fluctuations have been found to exhibit patterns of bilateral synchrony, with correlated regions inferred to have functional connectivity. However, the relationship between resting-state hemodynamics and underlying neural activity has not been well established, making the neural underpinnings of functional connectivity networks unclear. In this study, neural activity and hemodynamics were recorded simultaneously over the bilateral cortex of awake and anesthetized Thy1-GCaMP mice using wide-field optical mapping. Neural activity was visualized via selective expression of the calcium-sensitive fluorophore GCaMP in layer 2/3 and 5 excitatory neurons. Characteristic patterns of resting-state hemodynamics were accompanied by more rapidly changing bilateral patterns of resting-state neural activity. Spatiotemporal hemodynamics could be modeled by convolving this neural activity with hemodynamic response functions derived through both deconvolution and gamma-variate fitting. Simultaneous imaging and electrophysiology confirmed that Thy1-GCaMP signals are well-predicted by multiunit activity. Neurovascular coupling between resting-state neural activity and hemodynamics was robust and fast in awake animals, whereas coupling in urethane-anesthetized animals was slower, and in some cases included lower-frequency (<0.04 Hz) hemodynamic fluctuations that were not well-predicted by local Thy1-GCaMP recordings. These results support that resting-state hemodynamics in the awake and anesthetized brain are coupled to underlying patterns of excitatory neural activity. The patterns of bilaterally-symmetric spontaneous neural activity revealed by wide-field Thy1-GCaMP imaging may depict the neural foundation of functional connectivity networks detected in resting-state fMRI.

  7. Spatiotemporal trends of illegal activities from ranger-collected data in a Ugandan national park.

    PubMed

    Critchlow, R; Plumptre, A J; Driciru, M; Rwetsiba, A; Stokes, E J; Tumwesigye, C; Wanyama, F; Beale, C M

    2015-10-01

    Within protected areas, biodiversity loss is often a consequence of illegal resource use. Understanding the patterns and extent of illegal activities is therefore essential for effective law enforcement and prevention of biodiversity declines. We used extensive data, commonly collected by ranger patrols in many protected areas, and Bayesian hierarchical models to identify drivers, trends, and distribution of multiple illegal activities within the Queen Elizabeth Conservation Area (QECA), Uganda. Encroachment (e.g., by pastoralists with cattle) and poaching of noncommercial animals (e.g., snaring bushmeat) were the most prevalent illegal activities within the QECA. Illegal activities occurred in different areas of the QECA. Poaching of noncommercial animals was most widely distributed within the national park. Overall, ecological covariates, although significant, were not useful predictors for occurrence of illegal activities. Instead, the location of illegal activities in previous years was more important. There were significant increases in encroachment and noncommercial plant harvesting (nontimber products) during the study period (1999-2012). We also found significant spatiotemporal variation in the occurrence of all activities. Our results show the need to explicitly model ranger patrol effort to reduce biases from existing uncorrected or capture per unit effort analyses. Prioritization of ranger patrol strategies is needed to target illegal activities; these strategies are determined by protected area managers, and therefore changes at a site-level can be implemented quickly. These strategies should also be informed by the location of past occurrences of illegal activity: the most useful predictor of future events. However, because spatial and temporal changes in illegal activities occurred, regular patrols throughout the protected area, even in areas of low occurrence, are also required.

  8. Spatio-temporal analysis of brain electrical activity in epilepsy based on cellular nonlinear networks

    NASA Astrophysics Data System (ADS)

    Gollas, Frank; Tetzlaff, Ronald

    2009-05-01

    Epilepsy is the most common chronic disorder of the nervous system. Generally, epileptic seizures appear without foregoing sign or warning. The problem of detecting a possible pre-seizure state in epilepsy from EEG signals has been addressed by many authors over the past decades. Different approaches of time series analysis of brain electrical activity already are providing valuable insights into the underlying complex dynamics. But the main goal the identification of an impending epileptic seizure with a sufficient specificity and reliability, has not been achieved up to now. An algorithm for a reliable, automated prediction of epileptic seizures would enable the realization of implantable seizure warning devices, which could provide valuable information to the patient and time/event specific drug delivery or possibly a direct electrical nerve stimulation. Cellular Nonlinear Networks (CNN) are promising candidates for future seizure warning devices. CNN are characterized by local couplings of comparatively simple dynamical systems. With this property these networks are well suited to be realized as highly parallel, analog computer chips. Today available CNN hardware realizations exhibit a processing speed in the range of TeraOps combined with low power consumption. In this contribution new algorithms based on the spatio-temporal dynamics of CNN are considered in order to analyze intracranial EEG signals and thus taking into account mutual dependencies between neighboring regions of the brain. In an identification procedure Reaction-Diffusion CNN (RD-CNN) are determined for short segments of brain electrical activity, by means of a supervised parameter optimization. RD-CNN are deduced from Reaction-Diffusion Systems, which usually are applied to investigate complex phenomena like nonlinear wave propagation or pattern formation. The Local Activity Theory provides a necessary condition for emergent behavior in RD-CNN. In comparison linear spatio-temporal

  9. Spatiotemporal Imaging of Glutamate-Induced Biophotonic Activities and Transmission in Neural Circuits

    PubMed Central

    Tang, Rendong; Dai, Jiapei

    2014-01-01

    The processing of neural information in neural circuits plays key roles in neural functions. Biophotons, also called ultra-weak photon emissions (UPE), may play potential roles in neural signal transmission, contributing to the understanding of the high functions of nervous system such as vision, learning and memory, cognition and consciousness. However, the experimental analysis of biophotonic activities (emissions) in neural circuits has been hampered due to technical limitations. Here by developing and optimizing an in vitro biophoton imaging method, we characterize the spatiotemporal biophotonic activities and transmission in mouse brain slices. We show that the long-lasting application of glutamate to coronal brain slices produces a gradual and significant increase of biophotonic activities and achieves the maximal effect within approximately 90 min, which then lasts for a relatively long time (>200 min). The initiation and/or maintenance of biophotonic activities by glutamate can be significantly blocked by oxygen and glucose deprivation, together with the application of a cytochrome c oxidase inhibitor (sodium azide), but only partly by an action potential inhibitor (TTX), an anesthetic (procaine), or the removal of intracellular and extracellular Ca2+. We also show that the detected biophotonic activities in the corpus callosum and thalamus in sagittal brain slices mostly originate from axons or axonal terminals of cortical projection neurons, and that the hyperphosphorylation of microtubule-associated protein tau leads to a significant decrease of biophotonic activities in these two areas. Furthermore, the application of glutamate in the hippocampal dentate gyrus results in increased biophotonic activities in its intrahippocampal projection areas. These results suggest that the glutamate-induced biophotonic activities reflect biophotonic transmission along the axons and in neural circuits, which may be a new mechanism for the processing of neural

  10. Spatiotemporal dissociation of brain activity underlying threat and reward in social anxiety disorder.

    PubMed

    A Richey, John; Ghane, Merage; Valdespino, Andrew; Coffman, Marika C; Strege, Marlene V; White, Susan W; Ollendick, Thomas H

    2016-10-19

    Social anxiety disorder (SAD) involves abnormalities in social motivation, which may be independent of well-documented differences in fear and arousal systems. Yet, the neurobiology underlying motivational difficulties in SAD is not well understood. The aim of the current study was to spatiotemporally dissociate reward circuitry dysfunction from alterations in fear and arousal-related neural activity during anticipation and notification of social and non-social reward and punishment. During fMRI acquisition, non-depressed adults with social anxiety disorder (SAD; N = 21) and age-, sex- and IQ-matched control subjects (N = 22) completed eight runs of an incentive delay task, alternating between social and monetary outcomes and interleaved in alternating order between gain and loss outcomes. Adults with SAD demonstrated significantly reduced neural activity in ventral striatum during the anticipation of positive but not negative social outcomes. No differences between the SAD and control groups were observed during anticipation of monetary gain or loss outcomes or during anticipation of negative social images. However, consistent with previous work, the SAD group demonstrated amygdala hyper-activity upon notification of negative social outcomes. Degraded anticipatory processing in bilateral ventral striatum in SAD was constrained exclusively to anticipation of positive social information and dissociable from the effects of negative social outcomes previously observed in the amygdala. Alterations in anticipation-related neural signals may represent a promising target for treatment that is not addressed by available evidence-based interventions, which focus primarily on fear extinction and habituation processes.

  11. Spatio-temporal activity in real time (STAR): Optimization of regional fMRI feedback

    PubMed Central

    Magland, Jeremy F.; Tjoa, Christopher W.; Childress, Anna Rose

    2011-01-01

    The use of real-time feedback has expanded fMRI from a brain probe to include potential brain interventions with significant therapeutic promise. However, whereas time-averaged blood oxygenation level-dependent (BOLD) signal measurement is usually sufficient for probing a brain state, the real-time (frame-to-frame) BOLD signal is noisy, compromising feedback accuracy. We have developed a new real-time processing technique (STAR) that combines noise-reduction properties of multi-voxel (e.g., whole-brain) techniques with the regional specificity critical for therapeutics. Nineteen subjects were given real-time feedback in a cognitive control task (imagining repetitive motor activity vs. spatial navigation), and were all able to control a visual feedback cursor based on whole-brain neural activity. The STAR technique was evaluated, retrospectively, for five a priori regions of interest in these data, and was shown to provide significantly better (frame-by-frame) classification accuracy than a regional BOLD technique. In addition to regional feedback signals, the output of the STAR technique includes spatio-temporal activity maps (movies) providing insight into brain dynamics. The STAR approach offers an appealing optimization for real-time fMRI applications requiring an anatomically-localized feedback signal. PMID:21232612

  12. The cerebellar Golgi cell and spatiotemporal organization of granular layer activity

    PubMed Central

    D'Angelo, Egidio; Solinas, Sergio; Mapelli, Jonathan; Gandolfi, Daniela; Mapelli, Lisa; Prestori, Francesca

    2013-01-01

    The cerebellar granular layer has been suggested to perform a complex spatiotemporal reconfiguration of incoming mossy fiber signals. Central to this role is the inhibitory action exerted by Golgi cells over granule cells: Golgi cells inhibit granule cells through both feedforward and feedback inhibitory loops and generate a broad lateral inhibition that extends beyond the afferent synaptic field. This characteristic connectivity has recently been investigated in great detail and been correlated with specific functional properties of these neurons. These include theta-frequency pacemaking, network entrainment into coherent oscillations and phase resetting. Important advances have also been made in terms of determining the membrane and synaptic properties of the neuron, and clarifying the mechanisms of activation by input bursts. Moreover, voltage sensitive dye imaging and multi-electrode array (MEA) recordings, combined with mathematical simulations based on realistic computational models, have improved our understanding of the impact of Golgi cell activity on granular layer circuit computations. These investigations have highlighted the critical role of Golgi cells in: generating dense clusters of granule cell activity organized in center-surround structures, implementing combinatorial operations on multiple mossy fiber inputs, regulating transmission gain, and cut-off frequency, controlling spike timing and burst transmission, and determining the sign, intensity and duration of long-term synaptic plasticity at the mossy fiber-granule cell relay. This review considers recent advances in the field, highlighting the functional implications of Golgi cells for granular layer network computation and indicating new challenges for cerebellar research. PMID:23730271

  13. Active processing of spatio-temporal input patterns in silicon dendrites.

    PubMed

    Wang, Yingxue; Liu, Shih-Chii

    2013-06-01

    Capturing the functionality of active dendritic processing into abstract mathematical models will help us to understand the role of complex biophysical neurons in neuronal computation and to build future useful neuromorphic analog Very Large Scale Integrated (aVLSI) neuronal devices. Previous work based on an aVLSI multi-compartmental neuron model demonstrates that the compartmental response in the presence of either of two widely studied classes of active mechanisms, is a nonlinear sigmoidal function of the degree of either input temporal synchrony OR input clustering level. Using the same silicon model, this work expounds the interaction between both active mechanisms in a compartment receiving input patterns of varying temporal AND spatial clustering structure and demonstrates that this compartmental response can be captured by a combined sigmoid and radial-basis function over both input dimensions. This paper further shows that the response to input spatio-temporal patterns in a one-dimensional multi-compartmental dendrite, can be described by a radial-basis like function of the degree of temporal synchrony between the inter-compartmental inputs.

  14. Spatiotemporal patterns of mountain pine beetle activity in the southern Rocky Mountains.

    PubMed

    Chapman, Teresa B; Veblen, Thomas T; Schoennagel, Tania

    2012-10-01

    The current mountain pine beetle (MPB; Dendroctonus ponderosae) outbreak in the southern Rocky Mountains has impacted approximately 750 000 ha of forest. Weather and habitat heterogeneity influence forest insect population dynamics at multiple spatial and temporal scales. Comparison of forest insect population dynamics in two principal host species may elucidate the relative contribution of weather and landscape factors in initiating and driving extensive outbreaks. To investigate potential drivers of the current MPB outbreak, we compared broadscale spatiotemporal patterns of MPB activity in lodgepole pine (Pinus contorta) and ponderosa pine (Pinus ponderosa) from 1996 to 2010 in Colorado and southern Wyoming with regional weather fluctuations, and then tracked the annual meso-scale progression of the epidemic in lodgepole pine with respect to weather, topographic, previous MPB activity, and forest stand attributes. MPB activity in lodgepole pine compared to ponderosa pine showed higher magnitude and extent of spatial synchrony. Warm temperatures and low annual precipitation favorable to beetle populations showed high regional synchrony across areas of both pine species, suggesting that habitat interacts with weather in synchronizing MPB populations. Cluster analysis of time series patterns identified multiple, disjunct locations of incipient MPB activity (epicenters) in lodgepole pine, which overlapped an earlier 1980s MPB outbreak, and suggests a regional trigger (drought) across this homogenous forest type. Negative departures from mean annual precipitation played a key role in subsequent spread of MPB outbreak. Development of the outbreak was also associated with lower elevations, greater dominance by lodgepole pine, stands of larger tree size, and stands with higher percentage canopy cover. After epidemic levels of MPB activity were attained, MPB activity was less strongly associated with stand and weather variables. These results emphasize the importance of

  15. Neural speech recognition: continuous phoneme decoding using spatiotemporal representations of human cortical activity

    NASA Astrophysics Data System (ADS)

    Moses, David A.; Mesgarani, Nima; Leonard, Matthew K.; Chang, Edward F.

    2016-10-01

    Objective. The superior temporal gyrus (STG) and neighboring brain regions play a key role in human language processing. Previous studies have attempted to reconstruct speech information from brain activity in the STG, but few of them incorporate the probabilistic framework and engineering methodology used in modern speech recognition systems. In this work, we describe the initial efforts toward the design of a neural speech recognition (NSR) system that performs continuous phoneme recognition on English stimuli with arbitrary vocabulary sizes using the high gamma band power of local field potentials in the STG and neighboring cortical areas obtained via electrocorticography. Approach. The system implements a Viterbi decoder that incorporates phoneme likelihood estimates from a linear discriminant analysis model and transition probabilities from an n-gram phonemic language model. Grid searches were used in an attempt to determine optimal parameterizations of the feature vectors and Viterbi decoder. Main results. The performance of the system was significantly improved by using spatiotemporal representations of the neural activity (as opposed to purely spatial representations) and by including language modeling and Viterbi decoding in the NSR system. Significance. These results emphasize the importance of modeling the temporal dynamics of neural responses when analyzing their variations with respect to varying stimuli and demonstrate that speech recognition techniques can be successfully leveraged when decoding speech from neural signals. Guided by the results detailed in this work, further development of the NSR system could have applications in the fields of automatic speech recognition and neural prosthetics.

  16. Quorum activation at a distance: spatiotemporal patterns of gene regulation from diffusion of an autoinducer signal

    NASA Astrophysics Data System (ADS)

    Dilanji, Gabriel; Langebrake, Jessica; Deleenheer, Patrick; Hagen, Stephen J.

    2012-02-01

    Bacteria in colonies coordinate gene regulation through the exchange of diffusible signal molecules known as autoinducers (AI). This ``quorum signaling'' often occurs in physically heterogeneous and spatially extended environments such as biofilms. Under these conditions the space and time scales for diffusion of the signal limit the range and timing of effective gene regulation. We expect that spatial and temporal patterns of gene expression will reflect physical environmental constraints as well as nonlinear transcriptional activation and feedback within the gene regulatory system. We have combined experiments and modeling to investigate how these spatiotemporal patterns develop. We embed engineered plasmid/GFP quorum sensor strains or wild type strains in a long narrow agar lane, and then introduce AI signal at one terminus of the lane. Diffusion of the AI initiates reporter expression along the length of the lane, extending to macroscopic distances of mm-cm. Resulting patterns are captured quantitatively by a mathematical model that incorporates logistic growth of the population, diffusion of AI, and nonlinear transcriptional activation. Our results show that a diffusing quorum signal can coordinate gene expression over distances of order 1cm on time scales of order 10 hrs.

  17. Clustering and Recurring Anomaly Identification: Recurring Anomaly Detection System (ReADS)

    NASA Technical Reports Server (NTRS)

    McIntosh, Dawn

    2006-01-01

    This viewgraph presentation reviews the Recurring Anomaly Detection System (ReADS). The Recurring Anomaly Detection System is a tool to analyze text reports, such as aviation reports and maintenance records: (1) Text clustering algorithms group large quantities of reports and documents; Reduces human error and fatigue (2) Identifies interconnected reports; Automates the discovery of possible recurring anomalies; (3) Provides a visualization of the clusters and recurring anomalies We have illustrated our techniques on data from Shuttle and ISS discrepancy reports, as well as ASRS data. ReADS has been integrated with a secure online search

  18. Spatio-Temporal Progression of Cortical Activity Related to Continuous Overt and Covert Speech Production in a Reading Task

    PubMed Central

    Brumberg, Jonathan S.; Krusienski, Dean J.; Chakrabarti, Shreya; Gunduz, Aysegul; Brunner, Peter; Ritaccio, Anthony L.; Schalk, Gerwin

    2016-01-01

    How the human brain plans, executes, and monitors continuous and fluent speech has remained largely elusive. For example, previous research has defined the cortical locations most important for different aspects of speech function, but has not yet yielded a definition of the temporal progression of involvement of those locations as speech progresses either overtly or covertly. In this paper, we uncovered the spatio-temporal evolution of neuronal population-level activity related to continuous overt speech, and identified those locations that shared activity characteristics across overt and covert speech. Specifically, we asked subjects to repeat continuous sentences aloud or silently while we recorded electrical signals directly from the surface of the brain (electrocorticography (ECoG)). We then determined the relationship between cortical activity and speech output across different areas of cortex and at sub-second timescales. The results highlight a spatio-temporal progression of cortical involvement in the continuous speech process that initiates utterances in frontal-motor areas and ends with the monitoring of auditory feedback in superior temporal gyrus. Direct comparison of cortical activity related to overt versus covert conditions revealed a common network of brain regions involved in speech that may implement orthographic and phonological processing. Our results provide one of the first characterizations of the spatiotemporal electrophysiological representations of the continuous speech process, and also highlight the common neural substrate of overt and covert speech. These results thereby contribute to a refined understanding of speech functions in the human brain. PMID:27875590

  19. fMRI single trial discovery of spatio-temporal brain activity patterns.

    PubMed

    Allegra, Michele; Seyed-Allaei, Shima; Pizzagalli, Fabrizio; Baftizadeh, Fahimeh; Maieron, Marta; Reverberi, Carlo; Laio, Alessandro; Amati, Daniele

    2017-03-01

    There is growing interest in the description of short-lived patterns in the spatiotemporal cortical activity monitored via neuroimaging. Most traditional analysis methods, designed to estimate relatively long-term brain dynamics, are not always appropriate to capture these patterns. Here we introduce a novel data-driven approach for detecting short-lived fMRI brain activity patterns. Exploiting Density Peak Clustering (Rodriguez and Laio [2014]), our approach reveals well localized clusters by identifying and grouping together voxels whose time-series are similar, irrespective of their brain location, even when very short time windows (∼10 volumes) are used. The method, which we call Coherence Density Peak Clustering (CDPC), is first tested on simulated data and compared with a standard unsupervised approach for fMRI analysis, independent component analysis (ICA). CDPC identifies activated voxels with essentially no false-positives and proves more reliable than ICA, which is troubled by a number of false positives comparable to that of true positives. The reliability of the method is demonstrated on real fMRI data from a simple motor task, containing brief iterations of the same movement. The clusters identified are found in regions expected to be involved in the task, and repeat synchronously with the paradigm. The methodology proposed is especially suitable for the study of short-time brain dynamics and single trial experiments, where the event or task of interest cannot be repeated for the same subject, as happens, for instance, in problem-solving, learning and decision-making. A GUI implementation of our method is available for download at https://github.com/micheleallegra/CDPC. Hum Brain Mapp 38:1421-1437, 2017. © 2016 Wiley Periodicals, Inc.

  20. Spatiotemporally synchronized cancer combination therapy using photo-activated nanoparticle drug delivery systems (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hasan, Tayyaba

    2016-03-01

    This talk will introduce a new nanotechnology platform for cancer combination therapy that utilizes near infrared light activation not only for photodynamic damage but also as an extrinsic mechanism to initiate release of complimentary drugs to suppress dynamic bursts in molecular signaling networks that promote tumor cell survival and treatment escape. The goal is to achieve co-delivery with concomitant activity of photodynamic, molecular inhibitor and chemotherapeutic agents, selectively within the tumor. This approach overcomes challenges in achieving synergistic interactions using sequential drug delivery. Conventional drug delivery is compromised by the differential pharmacokinetics of individual agents and potentially antagonistic effects—such as vascular shutdown by one agent that limits delivery of the second. Here, photodynamic damage—which efficiently kills drug-resistant cells via damage of common proteins involved in drug-resistance (such as anti-apoptosis factors and drug-efflux transporters)—is synchronized spatially and temporally with the photo-initiated release of complimentary agents—to enable full interaction amongst the individual therapies. This spatiotemporal synchronization offers new prospects for exploiting time-sensitive synergistic interactions. Specific implementations of these concepts will be presented in preclinical models of cancer. Strategies to enable molecular-targeting of cancer cells via site-specific attachment of targeting moieties to the outer lipid shell of these nanovehicles will also be discussed. If successful in humans, this new paradigm for synchronized, tumor-focused combination therapy will ultimately supersede the present use of chronic drug injection by increasing efficacy per cycle whilst reducing systemic exposure to toxic drugs.

  1. Exploiting Recurring Structure in a Semantic Network

    NASA Technical Reports Server (NTRS)

    Wolfe, Shawn R.; Keller, Richard M.

    2004-01-01

    With the growing popularity of the Semantic Web, an increasing amount of information is becoming available in machine interpretable, semantically structured networks. Within these semantic networks are recurring structures that could be mined by existing or novel knowledge discovery methods. The mining of these semantic structures represents an interesting area that focuses on mining both for and from the Semantic Web, with surprising applicability to problems confronting the developers of Semantic Web applications. In this paper, we present representative examples of recurring structures and show how these structures could be used to increase the utility of a semantic repository deployed at NASA.

  2. Spatio-temporal PLC activation in parallel with intracellular Ca2+ wave propagation in mechanically stimulated single MDCK cells.

    PubMed

    Tsukamoto, Akira; Hayashida, Yasunori; Furukawa, Katsuko S; Ushida, Takashi

    2010-03-01

    Intracellular Ca2+ transients are evoked either by the opening of Ca2+ channels on the plasma membrane or by phospholipase C (PLC) activation resulting in IP3 production. Ca2+ wave propagation is known to occur in mechanically stimulated cells; however, it remains uncertain whether and how PLC activation is involved in intracellular Ca2+ wave propagation in mechanically stimulated cells. To answer these questions, it is indispensable to clarify the spatio-temporal relations between intracellular Ca2+ wave propagation and PLC activation. Thus, we visualized both cytosolic Ca2+ and PLC activation using a real-time dual-imaging system in individual Mardin-Darby Canine Kidney (MDCK) cells. This system allowed us to simultaneously observe intracellular Ca2+ wave propagation and PLC activation in a spatio-temporal manner in a single mechanically stimulated MDCK cell. The results showed that PLC was activated not only in the mechanically stimulated region but also in other subcellular regions in parallel with intracellular Ca2+ wave propagation. These results support a model in which PLC is involved in Ca2+ signaling amplification in mechanically stimulated cells.

  3. Anticancer drug released from near IR-activated prodrug overcomes spatiotemporal limits of singlet oxygen.

    PubMed

    Rajaputra, Pallavi; Bio, Moses; Nkepang, Gregory; Thapa, Pritam; Woo, Sukyung; You, Youngjae

    2016-04-01

    Photodynamic therapy (PDT) is a cancer treatment modality where photosensitizer (PS) is activated by visible and near IR light to produce singlet oxygen ((1)O2). However, (1)O2 has a short lifetime (<40 ns) and cannot diffuse (<20 nm) beyond the cell diameter (e.g., ∼ 1800 nm). Thus, (1)O2 damage is both spatially and temporally limited and does not produce bystander effect. In a heterogeneous tumor, cells escaping (1)O2 damage can regrow after PDT treatment. To overcome these limitations, we developed a prodrug concept (PS-L-D) composed of a photosensitizer (PS), an anti-cancer drug (D), and an (1)O2-cleavable linker (L). Upon illumination of the prodrug, (1)O2 is generated, which damages the tumor and also releases anticancer drug. The locally released drug could cause spatially broader and temporally sustained damage, killing the surviving cancer cells after the PDT damage. In our previous report, we presented the superior activity of our prodrug of CA4 (combretastatin A-4), Pc-(L-CA4)2, compared to its non-cleavable analog, Pc-(NCL-CA4)2, that produced only PDT effects. Here, we provide clear evidence demonstrating that the released anticancer drug, CA4, indeed damages the surviving cancer cells over and beyond the spatial and temporal limits of (1)O2. In the limited light illumination experiment, cells in the entire well were killed due to the effect of released anti-cancer drug, whereas only a partial damage was observed in the pseudo-prodrug treated wells. A time-dependent cell survival study showed more cell death in the prodrug-treated cells due to the sustained damage by the released CA4. Cell cycle analysis and microscopic imaging data demonstrated the typical damage patterns by CA4 in the prodrug treated cells. A time-dependent histological study showed that prodrug-treated tumors lacked mitotic bodies, and the prodrug caused broader and sustained tumor size reduction compared to those seen in the tumors treated with the pseudo-prodrug. This data

  4. Device and programming abstractions for spatiotemporal control of active micro-particle swarms.

    PubMed

    Lam, Amy T; Samuel-Gama, Karina G; Griffin, Jonathan; Loeun, Matthew; Gerber, Lukas C; Hossain, Zahid; Cira, Nate J; Lee, Seung Ah; Riedel-Kruse, Ingmar H

    2017-03-21

    We present a hardware setup and a set of executable commands for spatiotemporal programming and interactive control of a swarm of self-propelled microscopic agents inside a microfluidic chip. In particular, local and global spatiotemporal light stimuli are used to direct the motion of ensembles of Euglena gracilis, a unicellular phototactic organism. We develop three levels of programming abstractions (stimulus space, swarm space, and system space) to create a scripting language for directing swarms. We then implement a multi-level proof-of-concept biotic game using these commands to demonstrate their utility. These device and programming concepts will enhance our capabilities for manipulating natural and synthetic swarms, with future applications for on-chip processing, diagnostics, education, and research on collective behaviors.

  5. Monitoring the Spatiotemporal Activities of miRNAs in Small Animal Models Using Molecular Imaging Modalities

    PubMed Central

    Baril, Patrick; Ezzine, Safia; Pichon, Chantal

    2015-01-01

    MicroRNAs (miRNAs) are a class of small non-coding RNAs that regulate gene expression by binding mRNA targets via sequence complementary inducing translational repression and/or mRNA degradation. A current challenge in the field of miRNA biology is to understand the functionality of miRNAs under physiopathological conditions. Recent evidence indicates that miRNA expression is more complex than simple regulation at the transcriptional level. MiRNAs undergo complex post-transcriptional regulations such miRNA processing, editing, accumulation and re-cycling within P-bodies. They are dynamically regulated and have a well-orchestrated spatiotemporal localization pattern. Real-time and spatio-temporal analyses of miRNA expression are difficult to evaluate and often underestimated. Therefore, important information connecting miRNA expression and function can be lost. Conventional miRNA profiling methods such as Northern blot, real-time PCR, microarray, in situ hybridization and deep sequencing continue to contribute to our knowledge of miRNA biology. However, these methods can seldom shed light on the spatiotemporal organization and function of miRNAs in real-time. Non-invasive molecular imaging methods have the potential to address these issues and are thus attracting increasing attention. This paper reviews the state-of-the-art of methods used to detect miRNAs and discusses their contribution in the emerging field of miRNA biology and therapy. PMID:25749473

  6. Recurring Slope Lineae on Mars: Atmospheric Origin?

    NASA Astrophysics Data System (ADS)

    McEwen, AS; Chojnacki, M.; Dundas, C.; Ojha, L.; Masse, M.; Schaefer, E.; Leung, C.

    2015-10-01

    Recurring Slope Lineae (RSL) are seasonal flows or seeps on warm Martian slopes. Observed gradual or incremental growth, fading, and yearly recurrence can be explained by seasonal seeps of water, which is probably salty. The origin of the water is not understood, but several observations indicate a key role for atmospheric processes. If sufficient deliquescent salts are present at these locations, the water could be entirely of atmospheric origin.

  7. Spectral evidence for hydrated salts in recurring slope lineae on Mars

    NASA Astrophysics Data System (ADS)

    Ojha, Lujendra; Wilhelm, Mary Beth; Murchie, Scott L.; McEwen, Alfred S.; Wray, James J.; Hanley, Jennifer; Massé, Marion; Chojnacki, Matt

    2015-11-01

    Determining whether liquid water exists on the Martian surface is central to understanding the hydrologic cycle and potential for extant life on Mars. Recurring slope lineae, narrow streaks of low reflectance compared to the surrounding terrain, appear and grow incrementally in the downslope direction during warm seasons when temperatures reach about 250-300 K, a pattern consistent with the transient flow of a volatile species. Brine flows (or seeps) have been proposed to explain the formation of recurring slope lineae, yet no direct evidence for either liquid water or hydrated salts has been found. Here we analyse spectral data from the Compact Reconnaissance Imaging Spectrometer for Mars instrument onboard the Mars Reconnaissance Orbiter from four different locations where recurring slope lineae are present. We find evidence for hydrated salts at all four locations in the seasons when recurring slope lineae are most extensive, which suggests that the source of hydration is recurring slope lineae activity. The hydrated salts most consistent with the spectral absorption features we detect are magnesium perchlorate, magnesium chlorate and sodium perchlorate. Our findings strongly support the hypothesis that recurring slope lineae form as a result of contemporary water activity on Mars.

  8. Visiting the wizard: children's memory for a recurring event.

    PubMed

    Price, D W; Goodman, G S

    1990-06-01

    The development of children's scripts for a recurring event was examined. 24 girls--2.5, 4, and 5.5 years of age--repeatedly experienced an initially novel episode (a trip to the "wizard's room") in a laboratory setting. Based on parents' ratings, the episode was defined as consisting of 26 actions organized into 7 activities. The sequential, spatial, and causal relations among the activities remained constant across episodes. Each child's knowledge of the recurring event was assessed by 4 probe conditions: free recall, prop reenactment, in-context reenactment, and in-context deviations. Results support conclusions that during early stages of script formation: (a) more actions and activities are included with age in children's scripts, (b) causally related activities are sequenced at all ages but temporal ordering is age-related, (c) hierarchical organization of actions within activities emerges gradually over the preschool years, and (d) probe conditions strongly influence performance for the younger but not for the older children.

  9. Improving spatio-temporal resolution of infrared images to detect thermal activity of defect at the surface of inorganic glass

    NASA Astrophysics Data System (ADS)

    Corvec, Guillaume; Robin, Eric; Le Cam, Jean-Benoît; Sangleboeuf, Jean-Christophe; Lucas, Pierre

    2016-07-01

    This paper proposes a noise suppression methodology to improve the spatio-temporal resolution of infrared images. The methodology is divided in two steps. The first one consists in removing the noise from the temporal signal at each pixel. Three basic temporal filters are considered for this purpose: average filter, cost function minimization (FIT) and short time Fast Fourier Transform approach (STFFT). But while this step effectively reduces the temporal signal noise at each pixel, the infrared images may still appear noisy. This is due to a random distribution of a residual offset value of pixels signal. Hence in the second step, the residual offset is identified by considering thermal images for which no mechanical loading is applied. In this case, the temperature variation field is homogeneous and the value of temperature variation at each pixel is theoretically equal to zero. The method is first tested on synthetic images built from infrared computer-generated images combined with experimental noise. The results demonstrate that this approach permits to keep the spatial resolution of infrared images equal to 1 pixel. The methodology is then applied to characterize thermal activity of a defect at the surface of inorganic glass submitted to cyclic mechanical loading. The three basic temporal filters are quantitatively compared and contrasted. Results obtained demonstrate that, contrarily to a basic spatio-temporal approach, the denoising method proposed is suitable to characterize low thermal activity combined to strong spatial gradients induced by cyclic heterogeneous deformations.

  10. Assessing the spatiotemporal evolution of neuronal activation with single-trial event-related potentials and functional MRI.

    PubMed

    Eichele, Tom; Specht, Karsten; Moosmann, Matthias; Jongsma, Marijtje L A; Quiroga, Rodrigo Quian; Nordby, Helge; Hugdahl, Kenneth

    2005-12-06

    The brain acts as an integrated information processing system, which methods in cognitive neuroscience have so far depicted in a fragmented fashion. Here, we propose a simple and robust way to integrate functional MRI (fMRI) with single trial event-related potentials (ERP) to provide a more complete spatiotemporal characterization of evoked responses in the human brain. The idea behind the approach is to find brain regions whose fMRI responses can be predicted by paradigm-induced amplitude modulations of simultaneously acquired single trial ERPs. The method was used to study a variant of a two-stimulus auditory target detection (odd-ball) paradigm that manipulated predictability through alternations of stimulus sequences with random or regular target-to-target intervals. In addition to electrophysiologic and hemodynamic evoked responses to auditory targets per se, single-trial modulations were expressed during the latencies of the P2 (170-ms), N2 (200-ms), and P3 (320-ms) components and predicted spatially separated fMRI activation patterns. These spatiotemporal matches, i.e., the prediction of hemodynamic activation by time-variant information from single trial ERPs, permit inferences about regional responses using fMRI with the temporal resolution provided by electrophysiology.

  11. The Mechanism by Which a Propeptide-encoded pH Sensor Regulates Spatiotemporal Activation of Furin*

    PubMed Central

    Williamson, Danielle M.; Elferich, Johannes; Ramakrishnan, Parvathy; Thomas, Gary; Shinde, Ujwal

    2013-01-01

    The proprotein convertase furin requires the pH gradient of the secretory pathway to regulate its multistep, compartment-specific autocatalytic activation. Although His-69 within the furin prodomain serves as the pH sensor that detects transport of the propeptide-enzyme complex to the trans-Golgi network, where it promotes cleavage and release of the inhibitory propeptide, a mechanistic understanding of how His-69 protonation mediates furin activation remains unclear. Here we employ biophysical, biochemical, and computational approaches to elucidate the mechanism underlying the pH-dependent activation of furin. Structural analyses and binding experiments comparing the wild-type furin propeptide with a nonprotonatable His-69 → Leu mutant that blocks furin activation in vivo revealed protonation of His-69 reduces both the thermodynamic stability of the propeptide as well as its affinity for furin at pH 6.0. Structural modeling combined with mathematical modeling and molecular dynamic simulations suggested that His-69 does not directly contribute to the propeptide-enzyme interface but, rather, triggers movement of a loop region in the propeptide that modulates access to the cleavage site and, thus, allows for the tight pH regulation of furin activation. Our work establishes a mechanism by which His-69 functions as a pH sensor that regulates compartment-specific furin activation and provides insights into how other convertases and proteases may regulate their precise spatiotemporal activation. PMID:23653353

  12. On the Characterization of the Spatio-Temporal Profiles of Brain Activity Associated with Face Naming and the Tip-of-the-Tongue State: A Magnetoencephalographic (MEG) Study

    ERIC Educational Resources Information Center

    Lindin, Monica; Diaz, Fernando; Capilla, Almudena; Ortiz, Tomas; Maestu, Fernando

    2010-01-01

    The tip-of-the-tongue state (TOT) in face naming is a transient state of difficulty in access to a person's name along with the conviction that the name is known. The aim of the present study was to characterize the spatio-temporal course of brain activation in the successful naming and TOT states, by means of magnetoencephalography, during a…

  13. Imaging the Spatio-Temporal Dynamics of Supragranular Activity in the Rat Somatosensory Cortex in Response to Stimulation of the Paws

    PubMed Central

    Morales-Botello, M. L.; Aguilar, J.; Foffani, G.

    2012-01-01

    We employed voltage-sensitive dye (VSD) imaging to investigate the spatio-temporal dynamics of the responses of the supragranular somatosensory cortex to stimulation of the four paws in urethane-anesthetized rats. We obtained the following main results. (1) Stimulation of the contralateral forepaw evoked VSD responses with greater amplitude and smaller latency than stimulation of the contralateral hindpaw, and ipsilateral VSD responses had a lower amplitude and greater latency than contralateral responses. (2) While the contralateral stimulation initially activated only one focus, the ipsilateral stimulation initially activated two foci: one focus was typically medial to the focus activated by contralateral stimulation and was stereotaxically localized in the motor cortex; the other focus was typically posterior to the focus activated by contralateral stimulation and was stereotaxically localized in the somatosensory cortex. (3) Forepaw and hindpaw somatosensory stimuli activated large areas of the sensorimotor cortex, well beyond the forepaw and hindpaw somatosensory areas of classical somatotopic maps, and forepaw stimuli activated larger cortical areas with greater activation velocity than hindpaw stimuli. (4) Stimulation of the forepaw and hindpaw evoked different cortical activation dynamics: forepaw responses displayed a clear medial directionality, whereas hindpaw responses were much more uniform in all directions. In conclusion, this work offers a complete spatio-temporal map of the supragranular VSD cortical activation in response to stimulation of the paws, showing important somatotopic differences between contralateral and ipsilateral maps as well as differences in the spatio-temporal activation dynamics in response to forepaw and hindpaw stimuli. PMID:22829873

  14. Spatio-Temporal Cellular Dynamics of the Arabidopsis Flagellin Receptor Reveal Activation Status-Dependent Endosomal Sorting[C][W

    PubMed Central

    Beck, Martina; Zhou, Ji; Faulkner, Christine; MacLean, Daniel; Robatzek, Silke

    2012-01-01

    The activity of surface receptors is location specific, dependent upon the dynamic membrane trafficking network and receptor-mediated endocytosis (RME). Therefore, the spatio-temporal dynamics of RME are critical to receptor function. The plasma membrane receptor FLAGELLIN SENSING2 (FLS2) confers immunity against bacterial infection through perception of flagellin (flg22). Following elicitation, FLS2 is internalized into vesicles. To resolve FLS2 trafficking, we exploited quantitative confocal imaging for colocalization studies and chemical interference. FLS2 localizes to bona fide endosomes via two distinct endocytic trafficking routes depending on its activation status. FLS2 receptors constitutively recycle in a Brefeldin A (BFA)–sensitive manner, while flg22-activated receptors traffic via ARA7/Rab F2b– and ARA6/Rab F1–positive endosomes insensitive to BFA. FLS2 endocytosis required a functional Rab5 GTPase pathway as revealed by dominant-negative ARA7/Rab F2b. Flg22-induced FLS2 endosomal numbers were increased by Concanamycin A treatment but reduced by Wortmannin, indicating that activated FLS2 receptors are targeted to late endosomes. RME inhibitors Tyrphostin A23 and Endosidin 1 altered but did not block induced FLS2 endocytosis. Additional inhibitor studies imply the involvement of the actin-myosin system in FLS2 internalization and trafficking. Altogether, we report a dynamic pattern of subcellular trafficking for FLS2 and reveal a defined framework for ligand-dependent endocytosis of this receptor. PMID:23085733

  15. Spatio-Temporal Analysis of Micro Economic Activities in Rome Reveals Patterns of Mixed-Use Urban Evolution.

    PubMed

    Fiasconaro, Alessandro; Strano, Emanuele; Nicosia, Vincenzo; Porta, Sergio; Latora, Vito

    2016-01-01

    Understanding urban growth is one with understanding how society evolves to satisfy the needs of its individuals in sharing a common space and adapting to the territory. We propose here a quantitative analysis of the historical development of a large urban area by investigating the spatial distribution and the age of commercial activities in the whole city of Rome. We find that the age of activities of various categories presents a very interesting double exponential trend, with a transition possibly related to the long-term economical effects determined by the oil crisis of the Seventies. The diversification of commercial categories, studied through various measures of entropy, shows, among other interesting features, a saturating behaviour with the density of activities. Moreover, different couples of commercial categories exhibit over the years a tendency to attract in space. Our results demonstrate that the spatio-temporal distribution of commercial activities can provide important insights on the urbanisation processes at work, revealing specific and non trivial socio-economical dynamics, as the presence of crisis periods and expansion trends, and contributing to the characterisation of the maturity of urban areas.

  16. Spatio-Temporal Analysis of Micro Economic Activities in Rome Reveals Patterns of Mixed-Use Urban Evolution

    PubMed Central

    Fiasconaro, Alessandro; Strano, Emanuele; Nicosia, Vincenzo; Porta, Sergio; Latora, Vito

    2016-01-01

    Understanding urban growth is one with understanding how society evolves to satisfy the needs of its individuals in sharing a common space and adapting to the territory. We propose here a quantitative analysis of the historical development of a large urban area by investigating the spatial distribution and the age of commercial activities in the whole city of Rome. We find that the age of activities of various categories presents a very interesting double exponential trend, with a transition possibly related to the long-term economical effects determined by the oil crisis of the Seventies. The diversification of commercial categories, studied through various measures of entropy, shows, among other interesting features, a saturating behaviour with the density of activities. Moreover, different couples of commercial categories exhibit over the years a tendency to attract in space. Our results demonstrate that the spatio-temporal distribution of commercial activities can provide important insights on the urbanisation processes at work, revealing specific and non trivial socio-economical dynamics, as the presence of crisis periods and expansion trends, and contributing to the characterisation of the maturity of urban areas. PMID:26982028

  17. The spatio-temporal dynamics of PKA activity profile during mitosis and its correlation to chromosome segregation.

    PubMed

    Vandame, Pauline; Spriet, Corentin; Trinel, Dave; Gelaude, Armance; Caillau, Katia; Bompard, Coralie; Biondi, Emanuele; Bodart, Jean-François

    2014-01-01

    The cyclic adenosine monophosphate dependent kinase protein (PKA) controls a variety of cellular processes including cell cycle regulation. Here, we took advantages of genetically encoded FRET-based biosensors, using an AKAR-derived biosensor to characterize PKA activity during mitosis in living HeLa cells using a single-cell approach. We measured PKA activity changes during mitosis. HeLa cells exhibit a substantial increase during mitosis, which ends with telophase. An AKAREV T>A inactive form of the biosensor and H89 inhibitor were used to ascertain for the specificity of the PKA activity measured. On a spatial point of view, high levels of activity near to chromosomal plate during metaphase and anaphase were detected. By using the PKA inhibitor H89, we assessed the role of PKA in the maintenance of a proper division phenotype. While this treatment in our hands did not impaired cell cycle progression in a drastic manner, inhibition of PKA leads to a dramatic increase in chromososme misalignement on the spindle during metaphase that could result in aneuploidies. Our study emphasizes the insights that can be gained with genetically encoded FRET-based biosensors, which enable to overcome the shortcomings of classical methologies and unveil in vivo PKA spatiotemporal profiles in HeLa cells.

  18. Spatiotemporal mapping of the muscular activity of the gizzard of the chicken (Gallus domesticus).

    PubMed

    Lentle, R G; Reynolds, G; de Loubens, C; Hulls, C; Janssen, P W M; Ravindran, V

    2013-02-01

    We report the results of spatiotemporal mapping of the spontaneous actions of component muscles of the gizzard and associated structures in ex vivo preparations with combined superfusion and vascular perfusion. Ongoing spontaneous contraction of cranial and caudal thin muscles occurred at a frequency of 2.2 ± 0.1 cycles per minute. Contractions of M. tenuis craniodorsalis with mean duration of 2.8 ± 0.2 s commenced ventrally adjacent to the distal limit of the proventriculus and progressed dorsally at 2.02 ± 0.03 mm•s(-1) in a concerted front. Near simultaneous contraction of M. tenuis caudoventralis of mean duration of contraction of 4.7 ± 0.7 s commenced dorsally and progressed ventrally at a similar rate (2.1 ± 0.1 mm•s(-1)) and in a similar manner. Contraction of the caudoventralis preceded that of craniodorsalis (mean 1.1 ± 0.15 s). Contraction of the 2 tenuis muscles was synchronous with the first component peak of the cyclic increase in lumen pressure and with distension of the crassus musculature. Contraction of the M. crassus caudodorsalis muscle coincided with the second component peak and was followed by distension of the tenuis musculature. The latter commenced before the relaxation of the tenuis muscles. Contractions of the crassus muscle propagated rapidly at right angles to the orientation of the muscle fibers at a faster velocity than that of the tenuis musculature. The durations of the component peaks in lumen pressure indicated that the duration of crassus contraction was similar to that of the tenuis musculature.

  19. Distinct Spatiotemporal Activation Patterns of the Perirhinal-Entorhinal Network in Response to Cortical and Amygdala Input

    PubMed Central

    Willems, Janske G. P.; Wadman, Wytse J.; Cappaert, Natalie L. M.

    2016-01-01

    The perirhinal (PER) and entorhinal cortex (EC) receive input from the agranular insular cortex (AiP) and the subcortical lateral amygdala (LA) and the main output area is the hippocampus. Information transfer through the PER/EC network however, is not always guaranteed. It is hypothesized that this network actively regulates the (sub)cortical activity transfer to the hippocampal network and that the inhibitory system is involved in this function. This study determined the recruitment by the AiP and LA afferents in PER/EC network with the use of voltage sensitive dye (VSD) imaging in horizontal mouse brain slices. Electrical stimulation (500 μA) of the AiP induced activity that gradually propagated predominantly in the rostro-caudal direction: from the PER to the lateral EC (LEC). In the presence of 1 μM of the competitive γ-aminobutyric acid (GABAA) receptor antagonist bicuculline, AiP stimulation recruited the medial EC (MEC) as well. In contrast, LA stimulation (500 μA) only induced activity in the deep layers of the PER. In the presence of bicuculline, the initial population activity in the PER propagated further towards the superficial layers and the EC after a delay. The latency of evoked responses decreased with increasing stimulus intensities (50–500 μA) for both the AiP and LA stimuli. The stimulation threshold for evoking responses in the PER/EC network was higher for the LA than for the AiP. This study showed that the extent of the PER/EC network activation depends on release of inhibition. When GABAA dependent inhibition is reduced, both the AiP and the LA activate spatially overlapping regions, although in a distinct spatiotemporal fashion. It is therefore hypothesized that the inhibitory network regulates excitatory activity from both cortical and subcortical areas that has to be transmitted through the PER/EC network. PMID:27378860

  20. Integrated device for optical stimulation and spatiotemporal electrical recording of neural activity in light-sensitized brain tissue

    PubMed Central

    Zhang, Jiayi; Laiwalla, Farah; Kim, Jennifer A; Urabe, Hayato; Van Wagenen, Rick; Song, Yoon-Kyu; Connors, Barry W; Zhang, Feng; Deisseroth, Karl; Nurmikko, Arto V

    2010-01-01

    Neural stimulation with high spatial and temporal precision is desirable both for studying the real-time dynamics of neural networks and for prospective clinical treatment of neurological diseases. Optical stimulation of genetically targeted neurons expressing the light sensitive channel protein Channelrhodopsin (ChR2) has recently been reported as a means for millisecond temporal control of neuronal spiking activities with cell-type selectivity. This offers the prospect of enabling local delivery of optical stimulation and the simultaneous monitoring of the neural activity by electrophysiological means, both in the vicinity of and distant to the stimulation site. We report here a novel dual-modality hybrid device, which consists of a tapered coaxial optical waveguide (‘optrode’) integrated into a 100 element intra-cortical multi-electrode recording array. We first demonstrate the dual optical delivery and electrical recording capability of the single optrode in in vitro preparations of mouse retina, photo-stimulating the native retinal photoreceptors while recording light-responsive activities from ganglion cells. The dual-modality array device was then used in ChR2 transfected mouse brain slices. Specifically, epileptiform events were reliably optically triggered by the optrode and their spatiotemporal patterns were simultaneously recorded by the multi-electrode array. PMID:19721185

  1. Unique spatiotemporal activation pattern of Cdc42 by Gef1 and Scd1 promotes different events during cytokinesis

    PubMed Central

    Wei, Bin; Hercyk, Brian S.; Mattson, Nicholas; Mohammadi, Ahmad; Rich, Julie; DeBruyne, Erica; Clark, Mikayla M.; Das, Maitreyi

    2016-01-01

    The Rho-family GTPase Cdc42 regulates cell polarity and localizes to the cell division site. Cdc42 is activated by guanine nucleotide exchange factors (GEFs). We report that Cdc42 promotes cytokinesis via a unique spatiotemporal activation pattern due to the distinct action of its GEFs, Gef1 and Scd1, in fission yeast. Before cytokinetic ring constriction, Cdc42 activation, is Gef1 dependent, and after ring constriction, it is Scd1 dependent. Gef1 localizes to the actomyosin ring immediately after ring assembly and promotes timely onset of ring constriction. Gef1 is required for proper actin organization during cytokinesis, distribution of type V myosin Myo52 to the division site, and timely recruitment of septum protein Bgs1. In contrast, Scd1 localizes to the broader region of ingressing membrane during cytokinetic furrowing. Scd1 promotes normal septum formation, and scd1Δ cells display aberrant septa with reduced Bgs1 localization. Thus we define unique roles of the GEFs Gef1 and Scd1 in the regulation of distinct events during cytokinesis. Gef1 localizes first to the cytokinetic ring and promotes timely constriction, whereas Scd1 localizes later to the ingressing membrane and promotes septum formation. Our findings are consistent with reports that complexity in GTPase signaling patterns enables exquisite precision over the control of cellular processes. PMID:26941334

  2. Simultaneous spatiotemporal mapping of in situ pH and bacterial activity within an intact 3D microcolony structure

    NASA Astrophysics Data System (ADS)

    Hwang, Geelsu; Liu, Yuan; Kim, Dongyeop; Sun, Victor; Aviles-Reyes, Alejandro; Kajfasz, Jessica K.; Lemos, Jose A.; Koo, Hyun

    2016-09-01

    Biofilms are comprised of bacterial-clusters (microcolonies) enmeshed in an extracellular matrix. Streptococcus mutans can produce exopolysaccharides (EPS)-matrix and assemble microcolonies with acidic microenvironments that can cause tooth-decay despite the surrounding neutral-pH found in oral cavity. How the matrix influences the pH and bacterial activity locally remains unclear. Here, we simultaneously analyzed in situ pH and gene expression within intact biofilms and measured the impact of damage to the surrounding EPS-matrix. The spatiotemporal changes of these properties were characterized at a single-microcolony level following incubation in neutral-pH buffer. The middle and bottom-regions as well as inner-section within the microcolony 3D structure were resistant to neutralization (vs. upper and peripheral-region), forming an acidic core. Concomitantly, we used a green fluorescent protein (GFP) reporter to monitor expression of the pH-responsive atpB (PatpB::gfp) by S. mutans within microcolonies. The atpB expression was induced in the acidic core, but sharply decreased at peripheral/upper microcolony regions, congruent with local pH microenvironment. Enzymatic digestion of the surrounding matrix resulted in nearly complete neutralization of microcolony interior and down-regulation of atpB. Altogether, our data reveal that biofilm matrix facilitates formation of an acidic core within microcolonies which in turn activates S. mutans acid-stress response, mediating both the local environment and bacterial activity in situ.

  3. NeuroCa: integrated framework for systematic analysis of spatiotemporal neuronal activity patterns from large-scale optical recording data

    PubMed Central

    Jang, Min Jee; Nam, Yoonkey

    2015-01-01

    Abstract. Optical recording facilitates monitoring the activity of a large neural network at the cellular scale, but the analysis and interpretation of the collected data remain challenging. Here, we present a MATLAB-based toolbox, named NeuroCa, for the automated processing and quantitative analysis of large-scale calcium imaging data. Our tool includes several computational algorithms to extract the calcium spike trains of individual neurons from the calcium imaging data in an automatic fashion. Two algorithms were developed to decompose the imaging data into the activity of individual cells and subsequently detect calcium spikes from each neuronal signal. Applying our method to dense networks in dissociated cultures, we were able to obtain the calcium spike trains of ∼1000 neurons in a few minutes. Further analyses using these data permitted the quantification of neuronal responses to chemical stimuli as well as functional mapping of spatiotemporal patterns in neuronal firing within the spontaneous, synchronous activity of a large network. These results demonstrate that our method not only automates time-consuming, labor-intensive tasks in the analysis of neural data obtained using optical recording techniques but also provides a systematic way to visualize and quantify the collective dynamics of a network in terms of its cellular elements. PMID:26229973

  4. Simultaneous spatiotemporal mapping of in situ pH and bacterial activity within an intact 3D microcolony structure

    PubMed Central

    Hwang, Geelsu; Liu, Yuan; Kim, Dongyeop; Sun, Victor; Aviles-Reyes, Alejandro; Kajfasz, Jessica K.; Lemos, Jose A.; Koo, Hyun

    2016-01-01

    Biofilms are comprised of bacterial-clusters (microcolonies) enmeshed in an extracellular matrix. Streptococcus mutans can produce exopolysaccharides (EPS)-matrix and assemble microcolonies with acidic microenvironments that can cause tooth-decay despite the surrounding neutral-pH found in oral cavity. How the matrix influences the pH and bacterial activity locally remains unclear. Here, we simultaneously analyzed in situ pH and gene expression within intact biofilms and measured the impact of damage to the surrounding EPS-matrix. The spatiotemporal changes of these properties were characterized at a single-microcolony level following incubation in neutral-pH buffer. The middle and bottom-regions as well as inner-section within the microcolony 3D structure were resistant to neutralization (vs. upper and peripheral-region), forming an acidic core. Concomitantly, we used a green fluorescent protein (GFP) reporter to monitor expression of the pH-responsive atpB (PatpB::gfp) by S. mutans within microcolonies. The atpB expression was induced in the acidic core, but sharply decreased at peripheral/upper microcolony regions, congruent with local pH microenvironment. Enzymatic digestion of the surrounding matrix resulted in nearly complete neutralization of microcolony interior and down-regulation of atpB. Altogether, our data reveal that biofilm matrix facilitates formation of an acidic core within microcolonies which in turn activates S. mutans acid-stress response, mediating both the local environment and bacterial activity in situ. PMID:27604325

  5. Recurring priapism may be a symptom of voiding dysfunction – case report and literature review

    PubMed Central

    de Jesus, Lisieux Eyer; Teixeira, Leonardo; Bertelli, André

    2016-01-01

    ABSTRACT Recurring priapism is rare in pre-pubertal children and may be attributed to multiple causes. We propose that voiding dysfunction (VD) may also justify this symptom and detail a clinical case of recurring stuttering priapism associated to overactive bladder that completely resolved after usage of anticholinergics and urotherapy. Sacral parasympathetic activity is responsible for detrusor contraction and for spontaneous erections and a relationship between erections and bladder status has been proved in healthy subjects (morning erections) and models of medullar trauma. High bladder pressures and/or volumes, voiding incoordination and posterior urethritis can potentially trigger reflex erections. PMID:27256196

  6. Recurring waterbird mortalities and unusual etiologies

    USGS Publications Warehouse

    Cole, R.A.; Franson, J.C.; Boere, Gerard C.; Galbraith, Colin A.; Stroud, David A.

    2006-01-01

    Over the last decade, the National Wildlife Health Center of the United States Geological Survey has documented various largescale mortalities of birds caused by infectious and non-infectious disease agents. Some of these mortality events have unusual or unidentified etiologies and have been recurring. While some of the causes of mortalities have been elucidated, others remain in various stages of investigation and identification. Two examples are discussed: 1) Leyogonimus polyoon (Class: Trematoda), not found in the New World until 1999, causes severe enteritis and has killed over 15 000 American Coot Fulica americana in the upper mid-western United States. The geographic range of this parasite within North America is predicted to be limited to the Great Lakes Basin. 2) In the early 1990s, estimates of up to 6% of the North American population of the Eared Grebe Podiceps nigricollis died at Salton Sea, California, with smaller mortalities occurring throughout the 1990s. Birds were observed to have unusual preening behaviour, and to congregate at freshwater drains and move onto land. Suggested etiologies included interactions of contaminants, immuno-suppression, an unusual form of a bacterial disease, and an unknown biotoxin. During studies carried out from 2000 to 2003, Eared Grebe mortality did not approach the level seen in the early 1990s and, although bacteria were identified as minor factors, the principal cause of mortality remains undetermined. The potential population impact of these emerging and novel disease agents is currently unknown.

  7. Long-Term Spatiotemporal Reconfiguration of Neuronal Activity Revealed by Voltage-Sensitive Dye Imaging in the Cerebellar Granular Layer

    PubMed Central

    Gandolfi, Daniela; Mapelli, Jonathan; D'Angelo, Egidio

    2015-01-01

    Understanding the spatiotemporal organization of long-term synaptic plasticity in neuronal networks demands techniques capable of monitoring changes in synaptic responsiveness over extended multineuronal structures. Among these techniques, voltage-sensitive dye imaging (VSD imaging) is of particular interest due to its good spatial resolution. However, improvements of the technique are needed in order to overcome limits imposed by its low signal-to-noise ratio. Here, we show that VSD imaging can detect long-term potentiation (LTP) and long-term depression (LTD) in acute cerebellar slices. Combined VSD imaging and patch-clamp recordings revealed that the most excited regions were predominantly associated with granule cells (GrCs) generating EPSP-spike complexes, while poorly responding regions were associated with GrCs generating EPSPs only. The correspondence with cellular changes occurring during LTP and LTD was highlighted by a vector representation obtained by combining amplitude with time-to-peak of VSD signals. This showed that LTP occurred in the most excited regions lying in the core of activated areas and increased the number of EPSP-spike complexes, while LTD occurred in the less excited regions lying in the surround. VSD imaging appears to be an efficient tool for investigating how synaptic plasticity contributes to the reorganization of multineuronal activity in neuronal circuits. PMID:26294979

  8. A FRET biosensor reveals spatiotemporal activation and functions of aurora kinase A in living cells.

    PubMed

    Bertolin, Giulia; Sizaire, Florian; Herbomel, Gaëtan; Reboutier, David; Prigent, Claude; Tramier, Marc

    2016-09-14

    Overexpression of AURKA is a major hallmark of epithelial cancers. It encodes the multifunctional serine/threonine kinase aurora A, which is activated at metaphase and is required for cell cycle progression; assessing its activation in living cells is mandatory for next-generation drug design. We describe here a Förster's resonance energy transfer (FRET) biosensor detecting the conformational changes of aurora kinase A induced by its autophosphorylation on Thr288. The biosensor functionally replaces the endogenous kinase in cells and allows the activation of the kinase to be followed throughout the cell cycle. Inhibiting the catalytic activity of the kinase prevents the conformational changes of the biosensor. Using this approach, we discover that aurora kinase A activates during G1 to regulate the stability of microtubules in cooperation with TPX2 and CEP192. These results demonstrate that the aurora kinase A biosensor is a powerful tool to identify new regulatory pathways controlling aurora kinase A activation.

  9. A FRET biosensor reveals spatiotemporal activation and functions of aurora kinase A in living cells

    PubMed Central

    Bertolin, Giulia; Sizaire, Florian; Herbomel, Gaëtan; Reboutier, David; Prigent, Claude; Tramier, Marc

    2016-01-01

    Overexpression of AURKA is a major hallmark of epithelial cancers. It encodes the multifunctional serine/threonine kinase aurora A, which is activated at metaphase and is required for cell cycle progression; assessing its activation in living cells is mandatory for next-generation drug design. We describe here a Förster's resonance energy transfer (FRET) biosensor detecting the conformational changes of aurora kinase A induced by its autophosphorylation on Thr288. The biosensor functionally replaces the endogenous kinase in cells and allows the activation of the kinase to be followed throughout the cell cycle. Inhibiting the catalytic activity of the kinase prevents the conformational changes of the biosensor. Using this approach, we discover that aurora kinase A activates during G1 to regulate the stability of microtubules in cooperation with TPX2 and CEP192. These results demonstrate that the aurora kinase A biosensor is a powerful tool to identify new regulatory pathways controlling aurora kinase A activation. PMID:27624869

  10. An imaging flow cytometry-based approach to measuring the spatiotemporal calcium mobilisation in activated T cells.

    PubMed

    Cerveira, Joana; Begum, Julfa; Di Marco Barros, Rafael; van der Veen, Annemarthe G; Filby, Andrew

    2015-08-01

    Calcium ions (Ca(2+)) are a ubiquitous transducer of cellular signals controlling key processes such as proliferation, differentiation, secretion and metabolism. In the context of T cells, stimulation through the T cell receptor has been shown to induce the release of Ca(2+) from intracellular stores. This sudden elevation within the cytoplasm triggers the opening of ion channels in the plasma membrane allowing an influx of extracellular Ca(2+) that in turn activates key molecules such as calcineurin. This cascade ultimately results in gene transcription and changes in the cellular state. Traditional methods for measuring Ca(2+) include spectrophotometry, conventional flow cytometry (CFC) and live cell imaging techniques. While each method has strengths and weaknesses, none can offer a detailed picture of Ca(2+) mobilisation in response to various agonists. Here we report an Imaging Flow Cytometry (IFC)-based method that combines the throughput and statistical rigour of CFC with the spatial information of a microscope. By co-staining cells with Ca(2+) indicators and organelle-specific dyes we can address the spatiotemporal patterns of Ca(2+) flux in Jurkat cells after stimulation with anti-CD3. The multispectral, high-throughput nature of IFC means that the organelle co-staining functions to direct the measurement of Ca(2+) indicator fluorescence to either the endoplasmic reticulum (ER) or the mitochondrial compartments without the need to treat cells with detergents such as digitonin to eliminate cytoplasmic background. We have used this system to look at the cellular localisation of Ca(2+) after stimulating cells with CD3, thapsigargin or ionomycin in the presence or absence of extracellular Ca(2+). Our data suggest that there is a dynamic interplay between the ER and mitochondrial compartments and that mitochondria act as a sink for both intracellular and extracellular derived Ca(2+). Moreover, by generating an NFAT-GFP expressing Jurkat line, we were able to

  11. Multilevel Methodology for Simulation of Spatio-Temporal Systems with Heterogeneous Activity; Application to Spread of Valley Fever Fungus

    USGS Publications Warehouse

    Jammalamadaka, Rajanikanth

    2009-01-01

    This report consists of a dissertation submitted to the faculty of the Department of Electrical and Computer Engineering, in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Graduate College, The University of Arizona, 2008. Spatio-temporal systems with heterogeneity in their structure and behavior have two major problems associated with them. The first one is that such complex real world systems extend over very large spatial and temporal domains and consume so many computational resources to simulate that they are infeasible to study with current computational platforms. The second one is that the data available for understanding such systems is limited because they are spread over space and time making it hard to obtain micro and macro measurements. This also makes it difficult to get the data for validation of their constituent processes while simultaneously considering their global behavior. For example, the valley fever fungus considered in this dissertation is spread over a large spatial grid in the arid Southwest and typically needs to be simulated over several decades of time to obtain useful information. It is also hard to get the temperature and moisture data (which are two critical factors on which the survival of the valley fever fungus depends) at every grid point of the spatial domain over the region of study. In order to address the first problem, we develop a method based on the discrete event system specification which exploits the heterogeneity in the activity of the spatio-temporal system and which has been shown to be effective in solving relatively simple partial differential equation systems. The benefit of addressing the first problem is that it now makes it feasible to address the second problem. We address the second problem by making use of a multilevel methodology based on modeling and simulation and systems theory. This methodology helps us in the construction of models with different resolutions (base and

  12. Spatiotemporal chaos from bursting dynamics

    SciTech Connect

    Berenstein, Igal; De Decker, Yannick

    2015-08-14

    In this paper, we study the emergence of spatiotemporal chaos from mixed-mode oscillations, by using an extended Oregonator model. We show that bursting dynamics consisting of fast/slow mixed mode oscillations along a single attractor can lead to spatiotemporal chaotic dynamics, although the spatially homogeneous solution is itself non-chaotic. This behavior is observed far from the Hopf bifurcation and takes the form of a spatiotemporal intermittency where the system locally alternates between the fast and the slow phases of the mixed mode oscillations. We expect this form of spatiotemporal chaos to be generic for models in which one or several slow variables are coupled to activator-inhibitor type of oscillators.

  13. CIR-XL recurring for several years

    NASA Astrophysics Data System (ADS)

    Dósa, Melinda; Erdös, Géza

    2016-04-01

    The heliospheric magnetic flux is determined from the radial component of the magnetic field vector measured onboard interplanetary space probes. Earlier Ulysses research has shown remarkable independence of the flux from heliographic latitude. Here we are investigating whether any longitudinal variation exist in the 50 year long OMNI magnetic data set. When determining the heliographic longitude of the plasma source, correction was applied for the solar wind travel time. Significant recurrent enhancements of the magnetic flux was observed during the declining phase of the solar cycles. These flux enhancements are associated with co-rotating interaction regions (CIR) lasting several years. The recurrence period is slightly faster than the Carrington Rotation rate. The same, long lasting recurring features can be observed when plotting the deviation angle of the solar wind velocity vector from the radial direction. However, the deviation angle is small - in order of a few degrees - and cannot account for the observed flux increases. An increase of the magnetic field is clearly caused by the plasma compression associated to CIRs. Comparing interplanetary data with synoptic maps of the coronal magnetic field (PFSS modell) and coronal temperature data of ACE, we came to the possible explanation that these long-term structures are caused by fast speed solar wind originating from coronal holes. This results supports the idea that magnetic field lines from coronal holes spread out and reach to low latitudes as well. The recurrent longitudinal variation of the magnetic flux during the declining phase of the solar cycle has impact on the modulation of cosmic rays as well as on the frequency and intensity of space weather events.

  14. Effects of a Multicomponent Exercise Program on Spatiotemporal Gait Parameters, Risk of Falling and Physical Activity in Dementia Patients

    PubMed Central

    Perrochon, Anaïck; Tchalla, Achille E.; Bonis, Joelle; Perucaud, Florian; Mandigout, Stéphane

    2015-01-01

    Background Exercise programs are presumed to rehabilitate gait disorders and to reduce the risk of falling in dementia patients. This study aimed to analyze the specific effects of multicomponent exercise on gait disorders and to determine the association between gait impairments and the risk of falling in dementia patients before and after intervention. Methods We conducted an 8-week multicomponent exercise program in 16 dementia patients (age 86.7 ± 5.4 years). All participants were assessed several times for gait analysis (Locométrix®), Tinetti score and physical activity (Body Media SenseWear® Pro armband). Results After 8 weeks of the exercise program, the mean gait speed was 0.12 m/s faster than before the intervention (0.55 ± 0.17 vs. 0.67 ± 0.14 m/s). The multicomponent exercise program improved gait performance and Tinetti score (p < 0.05). Gait performance (gait speed, stride length) was correlated with the Tinetti score (p < 0.05). Conclusion Analysis of spatiotemporal gait parameters using an accelerometer method provided a quick and easy tool to estimate the benefits of an exercise program and the risk of falling. PMID:26557134

  15. The type III effector EspF coordinates membrane trafficking by the spatiotemporal activation of two eukaryotic signaling pathways

    PubMed Central

    Alto, Neal M.; Weflen, Andrew W.; Rardin, Matthew J.; Yarar, Defne; Lazar, Cheri S.; Tonikian, Raffi; Koller, Antonius; Taylor, Susan S.; Boone, Charles; Sidhu, Sachdev S.; Schmid, Sandra L.; Hecht, Gail A.; Dixon, Jack E.

    2007-01-01

    Bacterial toxins and effector proteins hijack eukaryotic enzymes that are spatially localized and display rapid signaling kinetics. However, the molecular mechanisms by which virulence factors engage highly dynamic substrates in the host cell environment are poorly understood. Here, we demonstrate that the enteropathogenic Escherichia coli (EPEC) type III effector protein EspF nucleates a multiprotein signaling complex composed of eukaryotic sorting nexin 9 (SNX9) and neuronal Wiskott-Aldrich syndrome protein (N-WASP). We demonstrate that a specific and high affinity association between EspF and SNX9 induces membrane remodeling in host cells. These membrane-remodeling events are directly coupled to N-WASP/Arp2/3–mediated actin nucleation. In addition to providing a biochemical mechanism of EspF function, we find that EspF dynamically localizes to membrane-trafficking organelles in a spatiotemporal pattern that correlates with SNX9 and N-WASP activity in living cells. Thus, our findings suggest that the EspF-dependent assembly of SNX9 and N-WASP represents a novel form of signaling mimicry used to promote EPEC pathogenesis and gastrointestinal disease. PMID:17893247

  16. The Importance of Spatiotemporal Information in Biological Motion Perception: White Noise Presented with a Step-like Motion Activates the Biological Motion Area.

    PubMed

    Callan, Akiko; Callan, Daniel; Ando, Hiroshi

    2017-02-01

    Humans can easily recognize the motion of living creatures using only a handful of point-lights that describe the motion of the main joints (biological motion perception). This special ability to perceive the motion of animate objects signifies the importance of the spatiotemporal information in perceiving biological motion. The posterior STS (pSTS) and posterior middle temporal gyrus (pMTG) region have been established by many functional neuroimaging studies as a locus for biological motion perception. Because listening to a walking human also activates the pSTS/pMTG region, the region has been proposed to be supramodal in nature. In this study, we investigated whether the spatiotemporal information from simple auditory stimuli is sufficient to activate this biological motion area. We compared spatially moving white noise, having a running-like tempo that was consistent with biological motion, with stationary white noise. The moving-minus-stationary contrast showed significant differences in activation of the pSTS/pMTG region. Our results suggest that the spatiotemporal information of the auditory stimuli is sufficient to activate the biological motion area.

  17. Spatiotemporal trends of terrestrial vegetation activity along the urban development intensity gradient in China's 32 major cities.

    PubMed

    Zhou, Decheng; Zhao, Shuqing; Liu, Shuguang; Zhang, Liangxia

    2014-08-01

    Terrestrial vegetation plays many pivotal roles in urban systems. However, the impacts of urbanization on vegetation are poorly understood. Here we examined the spatiotemporal trends of the vegetation activity measured by MODIS Enhanced Vegetation Index (EVI) along Urban Development Intensity (UDI) gradient in 32 major Chinese cities from 2000 to 2012. We also proposed to use a new set of concepts (i.e., actual, theoretical, and positive urbanization effects) to better understand and quantify the impacts of urbanization on vegetation activities. Results showed that the EVI decreased significantly along a rising UDI for 28 of 32 cities (p<0.05) in linear, convex or concave form, signifying the urbanization impacts on vegetation varied across cities and UDI zones within a city. Further, the actual urbanization effects were much weaker than the theoretical estimates because of the offsetting positive effects generated by multiple urban environmental and anthropogenic factors. Examining the relative changes of EVI in various UDI zones against that in the rural area (ΔEVI), which effectively removed the effects of climate variability, demonstrated that ΔEVI decreased markedly from 2000 to 2012 for about three-quarters of the cities in the exurban (0.05activities.

  18. Spatio-temporally precise activation of engineered receptor tyrosine kinases by light

    PubMed Central

    Grusch, Michael; Schelch, Karin; Riedler, Robert; Reichhart, Eva; Differ, Christopher; Berger, Walter; Inglés-Prieto, Álvaro; Janovjak, Harald

    2014-01-01

    Receptor tyrosine kinases (RTKs) are a large family of cell surface receptors that sense growth factors and hormones and regulate a variety of cell behaviours in health and disease. Contactless activation of RTKs with spatial and temporal precision is currently not feasible. Here, we generated RTKs that are insensitive to endogenous ligands but can be selectively activated by low-intensity blue light. We screened light-oxygen-voltage (LOV)-sensing domains for their ability to activate RTKs by light-activated dimerization. Incorporation of LOV domains found in aureochrome photoreceptors of stramenopiles resulted in robust activation of the fibroblast growth factor receptor 1 (FGFR1), epidermal growth factor receptor (EGFR) and rearranged during transfection (RET). In human cancer and endothelial cells, light induced cellular signalling with spatial and temporal precision. Furthermore, light faithfully mimicked complex mitogenic and morphogenic cell behaviour induced by growth factors. RTKs under optical control (Opto-RTKs) provide a powerful optogenetic approach to actuate cellular signals and manipulate cell behaviour. PMID:24986882

  19. Spatiotemporal dissociation of brain activity underlying subjective awareness, objective performance and confidence.

    PubMed

    Li, Qi; Hill, Zachary; He, Biyu J

    2014-03-19

    Despite intense recent research, the neural correlates of conscious visual perception remain elusive. The most established paradigm for studying brain mechanisms underlying conscious perception is to keep the physical sensory inputs constant and identify brain activities that correlate with the changing content of conscious awareness. However, such a contrast based on conscious content alone would not only reveal brain activities directly contributing to conscious perception, but also include brain activities that precede or follow it. To address this issue, we devised a paradigm whereby we collected, trial-by-trial, measures of objective performance, subjective awareness, and the confidence level of subjective awareness. Using magnetoencephalography recordings in healthy human volunteers, we dissociated brain activities underlying these different cognitive phenomena. Our results provide strong evidence that widely distributed slow cortical potentials (SCPs) correlate with subjective awareness, even after the effects of objective performance and confidence were both removed. The SCP correlate of conscious perception manifests strongly in its waveform, phase, and power. In contrast, objective performance and confidence were both contributed by relatively transient brain activity. These results shed new light on the brain mechanisms of conscious, unconscious, and metacognitive processing.

  20. Spatiotemporal analysis of soil moisture in using active and passive remotely sensed data and ground observations

    NASA Astrophysics Data System (ADS)

    Li, H.; Fang, B.; Lakshmi, V.

    2015-12-01

    Abstract: Soil moisture plays a vital role in ecosystem, biological processes, climate, weather and agriculture. The Soil Moisture Active Passive (SMAP) improves data by combining the advantages and avoiding the limitation of passive microwave remote sensing (low resolution), and active microwave (challenge of soil moisture retrieval). This study will advance the knowledge of the application of soil moisture by using the Soil Moisture Active Passive Validation Experiment 2012 (SMAPVEX12) data as well as data collected at Walnut Gulch Arizona in August 2015 during SMAPVEX15. Specifically, we will analyze the 5m radar data from Unmanned Airborne Vehicle Synthetic Aperture Radar (UAVSAR) to study spatial variability within the PALS radiometer pixel. SMAPVEX12/15 and SMAP data will also be analyzed to evaluate disaggregation algorithms. The analytical findings will provide valuable information for policy-makers to initiate and adjust protocols and regulations for protecting land resources and improving environmental conditions. Keywords: soil moisture, Remote Sensing (RS), spatial statistic

  1. Locus Ceruleus Norepinephrine Release: A Central Regulator of CNS Spatio-Temporal Activation?

    PubMed Central

    Atzori, Marco; Cuevas-Olguin, Roberto; Esquivel-Rendon, Eric; Garcia-Oscos, Francisco; Salgado-Delgado, Roberto C.; Saderi, Nadia; Miranda-Morales, Marcela; Treviño, Mario; Pineda, Juan C.; Salgado, Humberto

    2016-01-01

    Norepinephrine (NE) is synthesized in the Locus Coeruleus (LC) of the brainstem, from where it is released by axonal varicosities throughout the brain via volume transmission. A wealth of data from clinics and from animal models indicates that this catecholamine coordinates the activity of the central nervous system (CNS) and of the whole organism by modulating cell function in a vast number of brain areas in a coordinated manner. The ubiquity of NE receptors, the daunting number of cerebral areas regulated by the catecholamine, as well as the variety of cellular effects and of their timescales have contributed so far to defeat the attempts to integrate central adrenergic function into a unitary and coherent framework. Since three main families of NE receptors are represented—in order of decreasing affinity for the catecholamine—by: α2 adrenoceptors (α2Rs, high affinity), α1 adrenoceptors (α1Rs, intermediate affinity), and β adrenoceptors (βRs, low affinity), on a pharmacological basis, and on the ground of recent studies on cellular and systemic central noradrenergic effects, we propose that an increase in LC tonic activity promotes the emergence of four global states covering the whole spectrum of brain activation: (1) sleep: virtual absence of NE, (2) quiet wake: activation of α2Rs, (3) active wake/physiological stress: activation of α2- and α1-Rs, (4) distress: activation of α2-, α1-, and β-Rs. We postulate that excess intensity and/or duration of states (3) and (4) may lead to maladaptive plasticity, causing—in turn—a variety of neuropsychiatric illnesses including depression, schizophrenic psychoses, anxiety disorders, and attention deficit. The interplay between tonic and phasic LC activity identified in the LC in relationship with behavioral response is of critical importance in defining the short- and long-term biological mechanisms associated with the basic states postulated for the CNS. While the model has the potential to explain a

  2. Spatio-temporal variability in the GDH activity to ammonium excretion ratio in epipelagic marine zooplankton

    NASA Astrophysics Data System (ADS)

    Fernández-Urruzola, I.; Osma, N.; Packard, T. T.; Maldonado, F.; Gómez, M.

    2016-11-01

    Glutamate dehydrogenase (GDH) activities have been widely used in oceanographic research as an index of in situ NH4+ excretion rates (RNH4+) in zooplankton. Here we study the variability in the relationship between the enzymatic rates and the actual rates measured in epipelagic marine zooplankton between several marine ecosystems. Although both measures were significantly correlated across zooplankton assemblages, the regression models yielded different GDH/RNH4+ ratios across ecosystems. Accordingly, the error of a general equation increased up to ±42.5 % when regressing all our data together. Aside from possible interspecific differences, some of the variability was explained by the unequal allometric relation that each rate maintained with protein. Scaling exponents were 1.38 for GDH activities and 0.87 for RNH4+, which would induce uncertainties in the GDH/RNH4+ ratios when organisms with different sizes were considered. Nevertheless, the main factor causing divergence between GDH activities and RNH4+ was the potential prey availability. We compared the excretory metabolism of the zooplankton community at different productivity periods in waters off Gran Canaria, and observed an important decrease in the RNH4+ during stratification. A similar decrease was found in the internal pool of glutamate, which may be critical in the regulation of in vivo rates. Strengthening our knowledge of the relationship between GDH activities and the RNH4+ will lead to more meaningful predictions of phytoplankton regeneration and community nitrogen fluxes across large spatial scales.

  3. Spatiotemporal Stability of Neonatal Rat Cardiomyocyte Monolayers Spontaneous Activity Is Dependent on the Culture Substrate

    PubMed Central

    Boudreau-Béland, Jonathan; Duverger, James Elber; Petitjean, Estelle; Maguy, Ange; Ledoux, Jonathan; Comtois, Philippe

    2015-01-01

    In native conditions, cardiac cells must continuously comply with diverse stimuli necessitating a perpetual adaptation. Polydimethylsiloxane (PDMS) is commonly used in cell culture to study cellular response to changes in the mechanical environment. The aim of this study was to evaluate the impact of using PDMS substrates on the properties of spontaneous activity of cardiomyocyte monolayer cultures. We compared PDMS to the gold standard normally used in culture: a glass substrate. Although mean frequency of spontaneous activity remained unaltered, incidence of reentrant activity was significantly higher in samples cultured on glass compared to PDMS substrates. Higher spatial and temporal instability of the spontaneous rate activation was found when cardiomyocytes were cultured on PDMS, and correlated with decreased connexin-43 and increased CaV3.1 and HCN2 mRNA levels. Compared to cultures on glass, cultures on PDMS were associated with the strongest response to isoproterenol and acetylcholine. These results reveal the importance of carefully selecting the culture substrate for studies involving mechanical stimulation, especially for tissue engineering or pharmacological high-throughput screening of cardiac tissue analog. PMID:26035822

  4. Bioresorbable Silicon Electronics for Transient Spatio-temporal Mapping of Electrical Activity from the Cerebral Cortex

    PubMed Central

    Hwang, Suk-Won; Kim, Bong Hoon; Juul, Halvor; Kim, Nam Heon; Won, Sang Min; Chiang, Ken; Trumpis, Michael; Richardson, Andrew G.; Cheng, Huanyu; Fang, Hui; Thomson, Marissa; Bink, Hank; Talos, Delia; Seo, Kyung Jin; Lee, Hee Nam; Kang, Seung-Kyun; Kim, Jae-Hwan; Lee, Jung Yup; Huang, Younggang; Jensen, Frances E.; Dichter, Marc A.; Lucas, Timothy H.; Viventi, Jonathan; Litt, Brian; Rogers, John A.

    2016-01-01

    Bioresorbable silicon electronics technology offers unprecedented opportunities to deploy advanced implantable monitoring systems that eliminate risks, cost and discomfort associated with surgical extraction. Applications include post-operative monitoring and transient physiologic recording after percutaneous or minimally invasive placement of vascular, cardiac, orthopedic, neural or other devices. We present an embodiment of these materials in both passive and actively addressed arrays of bioresorbable silicon electrodes with multiplexing capabilities, that record in vivo electrophysiological signals from the cortical surface and the subgaleal space. The devices detect normal physiologic and epileptiform activity, both in acute and chronic recordings. Comparative studies show sensor performance comparable to standard clinical systems and reduced tissue reactivity relative to conventional clinical electrocorticography (ECoG) electrodes. This technology offers general applicability in neural interfaces, with additional potential utility in treatment of disorders where transient monitoring and modulation of physiologic function, implant integrity and tissue recovery or regeneration are required. PMID:27088236

  5. A vascular anatomical network model of the spatio-temporal response to brain activation

    PubMed Central

    Boas, David A.; Jones, Stephanie R.; Devor, Anna; Huppert, Theodore J.; Dale, Anders M.

    2008-01-01

    Neuronal activity-induced changes in vascular tone and oxygen consumption result in a dynamic evolution of blood flow, volume, and oxygenation. Functional neuroimaging techniques, such as functional magnetic resonance imaging, optical imaging, and PET, provide indirect measures of the neural-induced vascular dynamics driving the blood parameters. Models connecting changes in vascular tone and oxygen consumption to observed changes in the blood parameters are needed to guide more quantitative physiological interpretation of these functional neuroimaging modalities. Effective lumped-parameter vascular balloon and Windkessel models have been developed for this purpose, but the lumping of the complex vascular network into a series of arterioles, capillaries, and venules allows only qualitative interpretation. We have therefore developed a parallel vascular anatomical network (VAN) model based on microscopically measurable properties to improve quantitative interpretation of the vascular response. The model, derived from measured physical properties, predicts baseline blood pressure and oxygen saturation distributions and dynamic responses consistent with literature. Furthermore, the VAN model allows investigation of spatial features of the dynamic vascular and oxygen response to neuronal activity. We find that a passive surround negative vascular response (“negative BOLD”) is predicted, but that it underestimates recently observed surround negativity suggesting that additional active surround vasoconstriction is required to explain the experimental data. PMID:18289880

  6. Regularized two-step brain activity reconstruction from spatiotemporal EEG data

    NASA Astrophysics Data System (ADS)

    Alecu, Teodor I.; Voloshynovskiy, Sviatoslav; Pun, Thierry

    2004-10-01

    We are aiming at using EEG source localization in the framework of a Brain Computer Interface project. We propose here a new reconstruction procedure, targeting source (or equivalently mental task) differentiation. EEG data can be thought of as a collection of time continuous streams from sparse locations. The measured electric potential on one electrode is the result of the superposition of synchronized synaptic activity from sources in all the brain volume. Consequently, the EEG inverse problem is a highly underdetermined (and ill-posed) problem. Moreover, each source contribution is linear with respect to its amplitude but non-linear with respect to its localization and orientation. In order to overcome these drawbacks we propose a novel two-step inversion procedure. The solution is based on a double scale division of the solution space. The first step uses a coarse discretization and has the sole purpose of globally identifying the active regions, via a sparse approximation algorithm. The second step is applied only on the retained regions and makes use of a fine discretization of the space, aiming at detailing the brain activity. The local configuration of sources is recovered using an iterative stochastic estimator with adaptive joint minimum energy and directional consistency constraints.

  7. Spatiotemporal control of microRNA function using light-activated antagomirs.

    PubMed

    Connelly, Colleen M; Uprety, Rajendra; Hemphill, James; Deiters, Alexander

    2012-11-01

    MicroRNAs (miRNAs) are small non-coding RNAs that act as post-transcriptional gene regulators and have been shown to regulate many biological processes including embryonal development, cell differentiation, apoptosis, and proliferation. Variations in the expression of certain miRNAs have been linked to a wide range of human diseases - especially cancer - and the diversity of miRNA targets suggests that they are involved in various cellular networks. Several tools have been developed to control the function of individual miRNAs and have been applied to study their biogenesis, biological role, and therapeutic potential; however, common methods lack a precise level of control that allows for the study of miRNA function with high spatial and temporal resolution. Light-activated miRNA antagomirs for mature miR-122 and miR-21 were developed through the site-specific installation of caging groups on the bases of selected nucleotides. Installation of caged nucleotides led to complete inhibition of the antagomir-miRNA hybridization and thus inactivation of antagomir function. The miRNA-inhibitory activity of the caged antagomirs was fully restored upon decaging through a brief UV irradiation. The synthesized antagomirs were applied to the photochemical regulation of miRNA function in mammalian cells. Moreover, spatial control over antagomir activity was obtained in mammalian cells through localized UV exposure. The presented approach enables the precise regulation of miRNA function and miRNA networks with unprecedented spatial and temporal resolution using UV irradiation and can be extended to any miRNA of interest.

  8. Cloud-to-ground lightning activity over Greece: Spatio-temporal analysis and impacts

    NASA Astrophysics Data System (ADS)

    Matsangouras, I. T.; Nastos, P. T.; Kapsomenakis, J.

    2016-03-01

    Cloud-to-ground (CG) lightning activity recorded by the Hellenic National Meteorological Service (HNMS) Precision Lightning Network (PLN) is analysed over the wider area of Greece. In addition, the spatial and temporal relationships between TRMM 3B42 (Tropical Rainfall Measuring Mission) datasets and lightning are presented. The analyses concern the period from January 14, 2008 to December 31, 2012. The Laboratory of Climatology and Atmospheric Environment, University of Athens, has established a detailed dataset of lightning impacts over Greece from 1895 to 2013, based on digitized archive editions of newspapers. The mean seasonal variability of CG lightning activity revealed autumn as the most dominant season with 303 LD, while the mean monthly variability of CG indicated October as the most lightning active month and May as the month with a mean of 27 LD. The mean annual spatial distribution of CG lightning per km2, depicted the maximum frequency over Pindus mountain range (> 7 CG/km2). During the autumn season, the northern Ionian Sea experienced a mean frequency of more than 5 CG/km2, compared to the southern Ionian Sea and NW Peloponnesus, where values of more than 7 CG/km2 are depicted. During the summer season, the maximum frequency appeared along Pindus mountain range, around Attica, Thessaly and central Macedonia highlands. The spatial distribution of seasonal correlations between the number of CG flashes/day and gridded (TRMM 3B42) daily rainfall totals for the period 2008-2012 over Greece, indicated that correlations were mainly positive all over the under study area, within all seasons, and especially during summer and autumn. Regarding the lightning impacts in Greece, based on the 1895-2013 study period, more than 343 fatalities and at least 224 injured people have been recorded. The spatial analysis of lightning impacts, showed that the majority of events has been recorded over Greek mainland and only few scattered events have been reported over

  9. Spatiotemporal imaging of cortical activation during verb generation and picture naming.

    PubMed

    Edwards, Erik; Nagarajan, Srikantan S; Dalal, Sarang S; Canolty, Ryan T; Kirsch, Heidi E; Barbaro, Nicholas M; Knight, Robert T

    2010-03-01

    One hundred and fifty years of neurolinguistic research has identified the key structures in the human brain that support language. However, neither the classic neuropsychological approaches introduced by Broca (1861) and Wernicke (1874), nor modern neuroimaging employing PET and fMRI has been able to delineate the temporal flow of language processing in the human brain. We recorded the electrocorticogram (ECoG) from indwelling electrodes over left hemisphere language cortices during two common language tasks, verb generation and picture naming. We observed that the very high frequencies of the ECoG (high-gamma, 70-160 Hz) track language processing with spatial and temporal precision. Serial progression of activations is seen at a larger timescale, showing distinct stages of perception, semantic association/selection, and speech production. Within the areas supporting each of these larger processing stages, parallel (or "incremental") processing is observed. In addition to the traditional posterior vs. anterior localization for speech perception vs. production, we provide novel evidence for the role of premotor cortex in speech perception and of Wernicke's and surrounding cortex in speech production. The data are discussed with regards to current leading models of speech perception and production, and a "dual ventral stream" hybrid of leading speech perception models is given.

  10. Characterization of pharmaceutically active compounds in Beijing, China: Occurrence pattern, spatiotemporal distribution and its environmental implication.

    PubMed

    Ma, Ruixue; Wang, Bin; Yin, Lina; Zhang, Yizhe; Deng, Shubo; Huang, Jun; Wang, Yujue; Yu, Gang

    2017-02-05

    Pharmaceutically active compounds (PhACs) as an important group of "emerging contaminants" (ECs), have been highlighted and received global attentions in last decade. China has tremendous consumption of PhACs and the most pharmaceutical manufacturers worldwide. In this study, 33 PhACs (19 antibiotics included) were monitored in the Beiyun River basin in Beijing, China. The seasonal occurrence, temporal-spatial distribution and potential source were investigated. The total levels were about 2μgL(-1). Non-antibiotics were more frequently detected. The highest median concentrations were observed for caffeine (558ngL(-1)) and erythromycin (319ngL(-1)). Acetaminophen, erythromycin, diclofenac and N,N-diethyl-meta-toluamide showed highly significant seasonal variation, while caffeine, carbamazepine, metoprolol and most sulfonamides were more stable. The burden was most heavy in Qing River in both seasons (up to 4μgL(-1)). Antibiotics from veterinary use accounted for minor contribution in this region. The characteristics and trends were overviewed by comparing with our previous survey. The total level of 15 PhACs dropped significantly by 37% on average from 2013 to 2015. The proportion of caffeine, once a major component in 2013, reduced from 77% to 47%. The burden of these ECs in surface water of Beijing is remarkably reduced, suggesting the overall situation has been improving.

  11. Atypical Functional Brain Activation during a Multiple Object Tracking Task in Girls with Turner Syndrome: Neurocorrelates of Reduced Spatiotemporal Resolution

    ERIC Educational Resources Information Center

    Beaton, Elliott A.; Stoddard, Joel; Lai, Song; Lackey, John; Shi, Jianrong; Ross, Judith L.; Simon, Tony J.

    2010-01-01

    Turner syndrome is associated with spatial and numerical cognitive impairments. We hypothesized that these nonverbal cognitive impairments result from limits in spatial and temporal processing, particularly as it affects attention. To examine spatiotemporal attention in girls with Turner syndrome versus typically developing controls, we used a…

  12. Spatiotemporal pattern of motoneuron activation in the rostral lumbar and the sacral segments during locomotor-like activity in the neonatal mouse spinal cord.

    PubMed

    Bonnot, Agnès; Whelan, Patrick J; Mentis, George Z; O'Donovan, Michael J

    2002-02-01

    We used calcium imaging to visualize the spatiotemporal pattern of motoneuron activity during dorsal root-evoked locomotor-like bursting in the lumbosacral spinal cord of the neonatal mouse. Dorsal root stimuli elicited a tonic discharge in motoneurons on which alternating left-right rhythmic discharges were superimposed. Both the tonic and the rhythmic components could be recorded optically from populations of motoneurons labeled with calcium-green dextran. Optical and electrical recordings revealed that rhythmic signals from different parts of the lumbar (L1, L2) and sacral (S1-S3) segments rose, peaked, and decayed in a rostrocaudal sequence. This pattern gave rise to a rostrocaudal "wave" in the activation of motoneurons during each cycle of locomotor-like activity. A similar rostrocaudal delay was observed during episodes of alternation that occurred in the absence of stimulation, suggesting that this delay was not caused by the train of dorsal root stimuli. It is hypothesized that this behavior may simplify the appropriate sequencing of motoneurons during locomotion.

  13. Recurring Reports of Civilian Employment and Payrolls

    DTIC Science & Technology

    1989-09-11

    DARPA)* 7. Office of Civilian Health and Medical Program of the Uniformed Services (OCHAMPUS)* 8. Defense Medical Support Activity ( DMSA )* 9...Agency (DARPA)* 7. Office of Civilian Health and Medical Program of the Uniformed Services (OCHAMPUS)* 8. Defense Medical Support Activity ( DMSA )* 9...Support Activity ( DMSA )* 9. Washington Headquarters Services (WHS)* 10. Office of Economic Adjustment (OEA)* 11. Defense Legal Services Agency (DLSA

  14. Exploiting flow to control the in vitro spatiotemporal distribution of microbubble-seeded acoustic cavitation activity in ultrasound therapy.

    PubMed

    Pouliopoulos, Antonios N; Bonaccorsi, Simone; Choi, James J

    2014-11-21

    Focused ultrasound and microbubbles have been extensively used to generate therapeutic bioeffects. Despite encouraging in vivo results, there remains poor control of the magnitude and spatial distribution of these bioeffects due to the limited ability of conventional pulse shapes and sequences to control cavitation dynamics. Thus current techniques are restricted by an efficacy-safety trade-off. The primary aim of the present study was to incorporate the presence of flow in the design of new short pulse sequences, which can more uniformly distribute the cavitation activity. Microbubbles flowing (fluid velocity: 10 mm s(-1)) through a 300 μm tube were sonicated with a focused 0.5 MHz transducer while acoustic emissions were captured with an inserted focused 7.5 MHz passive cavitation detector. The two foci were co-axially aligned and their focal points were overlapped. Whereas conventional sequences are composed of a long burst (>10,000 cycles) emitted at a low burst repetition frequency (<10 Hz), we decomposed this burst into short pulses by adding intervals to facilitate inter-pulse microbubble movement. To evaluate how this sequence influenced cavitation distribution, we emitted short pulses (peak-rarefactional pressure (PRP): 40-366 kPa, pulse length (PL): 5-25 cycles) at high pulse repetition frequencies (PRF: 0.625-10 kHz) for a burst length of 100 ms. Increased cavitation persistence, implied by the duration of the microbubble acoustic emissions, was a measure of improved distribution due to the presence of flow. Sonication at lower acoustic pressures, longer pulse intervals and lower PLs improved the spatial distribution of cavitation. Furthermore, spectral analysis of the microbubble emissions revealed that the improvement at low pressures is due to persisting stable cavitation. In conclusion, new short-pulse sequences were shown to improve spatiotemporal control of acoustic cavitation dynamics during physiologically relevant flow. This

  15. Recurring Slope Lineae and Future Exploration of Mars

    NASA Astrophysics Data System (ADS)

    McEwen, Alfred; Byrne, Shane; Chevrier, Vincent; Chojnacki, Matt; Dundas, Colin; Masse, Marion; Mattson, Sarah; Ojha, Lujendra; Pommerol, Antoine; Toigo, Anthony; Wray, James

    2014-05-01

    Recurring slope lineae (RSL) on Mars may be evidence for the seasonal flow or seepage of water on relatively warm slopes. RSL are narrow (<5 m), relatively dark markings on steep (25°-40°) slopes that appear and incrementally grow during warm seasons over low-albedo surfaces, fade when inactive, and recur over multiple Mars years [McEwen et al., 2011, Science]. RSL often follow small gullies, but no topographic changes have been detected via 30 cm/pixel images from HiRISE on MRO. The fans on which RSL terminate have distinctive color and spectral properties in MRO/CRISM, but lack distinctive water absorption bands [Ojha et al., 2013, GRL]. The first group of confirmed RSL appear and lengthen in the late southern spring through summer from 48° - 32°S latitude, favoring equator-facing slopes—times and places with peak surface temperatures ranging from >250 K to >300 K. Over the past Martian year we have monitored active RSL in equatorial (0°-15°S) regions of Mars, especially in the deep canyons of Valles Marineris [McEwen et al., 2014, Nature Geoscience]. These equatorial RSL are especially active on north-facing slopes in northern summer and spring and on south-facing slopes in southern spring and summer, following the most normal solar incidence angles on these steep slopes. More recently we have confirmed RSL near 35°N in the low-albedo and low-altitude Acidalia Planitia. All RSL locations have warm peak daily temperatures (typically >273 K at the surface) in the seasons when RSL are active, and occur on steep, rocky, low-albedo slopes. However, most times and places with these properties lack apparent RSL, so there are additional, unseen requirements. We do not know what time of day RSL are actively flowing. Seasonal variation in the atmospheric column abundance of water vapor does not match the RSL activity. Seasonal melting of shallow ice best explains the RSL observations, but the origin and replenishment of such ice is not understood, especially in

  16. Equivalence between free-electron-laser oscillators and actively-mode-locked lasers: Detailed studies of temporal, spatiotemporal, and spectrotemporal dynamics

    SciTech Connect

    Bruni, C.; Legrand, T.; Szwaj, C.; Bielawski, S.; Couprie, M. E.

    2011-12-15

    We show experimentally and numerically that free-electron-laser (FEL) oscillators behave in a very similar way to conventional actively-mode-locked lasers. This stems from the similar structures of their underlying Haus equations. A comparative study of the temporal evolutions of the pulse train shapes and spatiotemporal regimes is performed on a Nd:YVO{sub 4} laser and a storage-ring free-electron laser. Furthermore, since direct observations of time-resolved pulse shapes and spectra are more accessible on free-electron lasers, the analogy also potentially enables one to investigate mode-locked laser dynamics using existing FEL facilities.

  17. Altered Spatiotemporal Dynamics of Cortical Activation to Tactile Stimuli in Somatosensory Area 3b and Area 1 of Monkeys after Spinal Cord Injury

    PubMed Central

    Su, Langting

    2016-01-01

    Abstract Reactivation of deafferented cortex plays a key role in mediating the recovery of lost functions, although the precise mechanism is not fully understood. This study simultaneously characterized the dynamic spatiotemporal features of tactile responses in areas 3b and 1 before and 6–8 weeks after partial dorsal column lesion (DCL), and examined how the reactivation relates to the recovery of simple hand use in squirrel monkeys. A combination of high spatiotemporal resolution functional intrinsic optical imaging, microelectrode mapping, behavioral assessment, and tracer histology methods were used. Compared with the normal cortex, we found that the responses of deafferented areas 3b and 1 to 3 s of continuous 8 Hz tactile stimulation of a single digit were significantly weaker and more transient. This finding indicates a loss of response to sustained tactile stimuli. The activation area enlarged for areas 3b and 1 in both directions along digit representation (medial–lateral) and across areas (anterior–posterior). All subjects showed behavioral deficits in a food reaching-grasping-retrieving task within the first 5 weeks after DCL, but recovered at the time when optical images were acquired. Summarily, we showed that these populations of cortical neurons responded to peripheral tactile inputs, albeit in significantly altered manners in each area, several weeks after deafferentation. We propose that compromised ascending driven inputs, impaired lateral inhibition, and local integration of input signals may account for the altered spatiotemporal dynamics of the reactivated areas 3b and 1 cortices. Further investigation with large sample sizes is needed to fully characterize the effects of deafferentation on area 1 activation size. PMID:27699211

  18. Discussion on spatio-temporal data model of mining-land use change

    NASA Astrophysics Data System (ADS)

    Liu, Chang-Hua; Zhang, Hou-Tian; Wang, Shi-Dong

    2009-12-01

    To build and apply Temporal Geographic Information System (TGIS), to manage mining land spatio-temporal data is a key research aspect for present production administration and ecological environment protection. Spatio-temporal database, whose foundation is spatio-temporal data model, is the core of TGIS. Considering the feature of land use to change, this paper builds up a model of mining land spatio-temporal data based on ground-state amended model with some improvements. This data model stores space information and time information of mining land in spatial database. From judging the spatio-temporal information in historical and current database, the land use situation at different historical period can be recurred very conveniently. At the same time, the mutual transforming situation among lands at different periods can be educed from overlaying the lands by use of the related analyzed function of GIS. Accordingly, that will give an important reference to open out the rule of mining land evolution.

  19. Integrating the ChE Curriculum via a Recurring Laboratory

    ERIC Educational Resources Information Center

    Kubilius, Matthew B.; Tu, Raymond S.; Anderson, Ryan

    2014-01-01

    A recurring framework has been integrated throughout the curriculum via a Continuously Stirred Tank Reactor (CSTR) platform. This laboratory is introduced during the material and energy balance course, and subsequent courses can use these results when explaining more advanced concepts. Further, this laboratory gives students practical experience…

  20. Kimura's Recurring-Figures-Test: A Normative Study.

    ERIC Educational Resources Information Center

    Rixecker, H.; Hartje, W.

    1980-01-01

    Administered Kimura's Recurring-Figures-Test to 427 normal subjects from Germany. A Kuder-Richardson test reliability was obtained. T-scale norms are given for two subgroups of different educational levels. Results indicated that the RFT is a valid instrument for the assessment of nonverbal memory function, and has a high test reliability. (Author)

  1. Detailed analysis of the spatio-temporal evolution of tremor, foreshock, and aftershock activities near the September 5, 2012 Nicoya Peninsula earthquake

    NASA Astrophysics Data System (ADS)

    Walter, J. I.; Peng, Z.; Schwartz, S. Y.; Meng, X.; Newman, A. V.; Protti, M.

    2013-05-01

    The subduction megathrust interface, at the Nicoya Peninsula, exhibits a wide range of complex fault behavior, from recently discovered slow slip and tremor, numerous microearthquakes, to infrequent megathrust (> Mw 7) earthquakes. In contrast to other subduction zones, the Nicoya tremor originates up-dip, down-dip, and within the seismogenic zone. The September 5, 2012 earthquake makes the Nicoya Peninsula uniquely poised to investigate the wide range of fault behavior and spatio-temporal evolution of seismic activity around the mainshock, as the seismogenic zone lies directly below the Peninsula. Preliminary matched-filter analysis using a template earthquake that precedes the mainshock by ~120 s indicates similar events occurring 20-40 min prior to the mainshock, as well as, immediately following the mainshock. We are expanding this analysis with a broader catalogue of template events and utilizing matched-filter codes optimized for graphics processing units (GPUs). While detailed analysis of the foreshock/aftershock sequence is ongoing, the early aftershocks cluster in a distinct region that is immediately adjacent to regions that have undergone slow slip in past events. We hope to gain better insight into the spatio-temporal transitions from stable sliding to stick-slip motion, and underlying physics of earthquake nucleation and interaction.

  2. Working memory load-dependent spatio-temporal activity of single-trial P3 response detected with an adaptive wavelet denoiser.

    PubMed

    Zhang, Qiushi; Yang, Xueqian; Yao, Li; Zhao, Xiaojie

    2017-03-27

    Working memory (WM) refers to the holding and manipulation of information during cognitive tasks. Its underlying neural mechanisms have been explored through both functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). Trial-by-trial coupling of simultaneously collected EEG and fMRI signals has become an important and promising approach to study the spatio-temporal dynamics of such cognitive processes. Previous studies have demonstrated a modulation effect of the WM load on both the BOLD response in certain brain areas and the amplitude of P3. However, much remains to be explored regarding the WM load-dependent relationship between the amplitude of ERP components and cortical activities, and the low signal-to-noise ratio (SNR) of the EEG signal still poses a challenge to performing single-trial analyses. In this paper, we investigated the spatio-temporal activities of P3 during an n-back verbal WM task by introducing an adaptive wavelet denoiser into the extraction of single-trial P3 features and using general linear model (GLM) to integrate simultaneously collected EEG and fMRI data. Our results replicated the modulation effect of the WM load on the P3 amplitude. Additionally, the activation of single-trial P3 amplitudes was detected in multiple brain regions, including the insula, the cuneus, the lingual gyrus (LG), and the middle occipital gyrus (MOG). Moreover, we found significant correlations between P3 features and behavioral performance. These findings suggest that the single-trial integration of simultaneous EEG and fMRI signals may provide new insights into classical cognitive functions.

  3. Spatiotemporal Wave Patterns: Information Dynamics

    SciTech Connect

    Mikhail Rabinovich; Lev Tsimring

    2006-01-20

    Pattern formation has traditionally been studied in non-equilibrium physics from the viewpoint of describing the basic structures and their interactions. While this is still an important area of research, the emphasis in the last few years has shifted towards analysis of specific properties of patterns in various complex media. For example, diverse and unexpected phenomena occur in neuro-like media that are characterized by highly non-trivial local dynamics. We carried out an active research program on analysis of spatio-temporal patterns in various physical systems (convection, oscillating fluid layer, soap film), as well as in neuro-like media, with an emphasis on informational aspects of the dynamics. Nonlinear nonequilibrium media and their discrete analogs have a unique ability to represent, memorize, and process the information contained in spatio-temporal patterns. Recent neurophysiological experiments demonstrated a certain universality of spatio-temporal representation of information by neural ensembles. Information processing is also revealed in the spatio-temporal dynamics of cellular patterns in nonequilibrium media. It is extremely important for many applications to study the informational aspects of these dynamics, including the origins and mechanisms of information generation, propagation and storage. Some of our results are: the discovery of self-organization of periodically oscillatory patterns in chaotic heterogeneous media; the analysis of the propagation of the information along a chaotic media as function of the entropy of the signal; the analysis of wave propagation in discrete non-equilibrium media with autocatalytic properties, which simulates the calcium dynamics in cellular membranes. Based on biological experiments we suggest the mechanism by which the spatial sensory information is transferred into the spatio-temporal code in the neural media. We also found a new mechanism of self-pinning in cellular structures and the related phenomenon

  4. Acute and recurring pericarditis: More colchicine, less corticosteroids

    PubMed Central

    Farand, Paul; Bonenfant, Francis; Belley-Côté, Emilie P; Tzouannis, Nicholas

    2010-01-01

    Acute and recurring pericarditis are frequently encountered clinical entities. Given that severe complications such as tamponade and constrictive pericarditis occur rarely, the majority of patients suffering from acute pericarditis will have a benign clinical course. However, pericarditis recurrence, with its painful symptoms, is frequent. In effect, recent studies have demonstrated a beneficial role of colchicine in preventing recurrence, while also suggesting an increase in recurrences with the use of corticosteroids, the traditional first-line agent. PMID:21191540

  5. Recurring errors among recent history of psychology textbooks.

    PubMed

    Thomas, Roger K

    2007-01-01

    Five recurring errors in history of psychology textbooks are discussed. One involves an identical misquotation. The remaining examples involve factual and interpretational errors that more than one and usually several textbook authors made. In at least 2 cases some facts were fabricated, namely, so-called facts associated with Pavlov's mugging and Descartes's reasons for choosing the pineal gland as the locus for mind-body interaction. A fourth example involves Broca's so-called discovery of the speech center, and the fifth example involves misinterpretations of Lloyd Morgan's intentions regarding his famous canon. When an error involves misinterpretation and thus misrepresentation, I will show why the misinterpretation is untenable.

  6. An empirical Bayes approach to analyzing recurring animal surveys

    USGS Publications Warehouse

    Johnson, D.H.

    1989-01-01

    Recurring estimates of the size of animal populations are often required by biologists or wildlife managers. Because of cost or other constraints, estimates frequently lack the accuracy desired but cannot readily be improved by additional sampling. This report proposes a statistical method employing empirical Bayes (EB) estimators as alternatives to those customarily used to estimate population size, and evaluates them by a subsampling experiment on waterfowl surveys. EB estimates, especially a simple limited-translation version, were more accurate and provided shorter confidence intervals with greater coverage probabilities than customary estimates.

  7. Discovering Recurring Anomalies in Text Reports Regarding Complex Space Systems

    NASA Technical Reports Server (NTRS)

    Zane-Ulman, Brett; Srivastava, Ashok N.

    2005-01-01

    Many existing complex space systems have a significant amount of historical maintenance and problem data bases that are stored in unstructured text forms. For some platforms, these reports may be encoded as scanned images rather than even searchable text. The problem that we address in this paper is the discovery of recurring anomalies and relationships between different problem reports that may indicate larger systemic problems. We will illustrate our techniques on data from discrepancy reports regarding software anomalies in the Space Shuttle. These free text reports are written by a number of different penp!e, thus the emphasis and wording varies considerably.

  8. Recurred Post-intubation Tracheal Stenosis Treated with Bronchoscopic Cryotherapy.

    PubMed

    Jung, Ye-Ryung; Taek Jeong, Joon; Kyu Lee, Myoung; Kim, Sang-Ha; Joong Yong, Suk; Jeong Lee, Seok; Lee, Won-Yeon

    Post-intubation tracheal stenosis accounts for the greatest proportion of whole-cause tracheal stenosis. Treatment of post-intubation tracheal stenosis requires a multidisciplinary approach. Surgery or an endoscopic procedure can be used, depending on the type of stenosis. However, the efficacy of cryotherapy in post-intubation tracheal stenosis has not been validated. Here, we report a case of recurring post-intubation tracheal stenosis successfully treated with bronchoscopic cryotherapy that had previously been treated with surgery. In this case, cryotherapy was effective in treating web-like fibrous stenosis, without requiring more surgery. Cryotherapy can be considered as an alternative or primary treatment for post-intubation tracheal stenosis.

  9. Variability in spatio-temporal pattern of trapezius activity and coordination of hand-arm muscles during a sustained repetitive dynamic task.

    PubMed

    Samani, Afshin; Srinivasan, Divya; Mathiassen, Svend Erik; Madeleine, Pascal

    2017-02-01

    The spatio-temporal distribution of muscle activity has been suggested to be a determinant of fatigue development. Pursuing this hypothesis, we investigated the pattern of muscular activity in the shoulder and arm during a repetitive dynamic task performed until participants' rating of perceived exertion reached 8 on Borg's CR-10 scale. We collected high-density surface electromyogram (HD-EMG) over the upper trapezius, as well as bipolar EMG from biceps brachii, triceps brachii, deltoideus anterior, serratus anterior, upper and lower trapezius from 21 healthy women. Root-mean-square (RMS) and mean power frequency (MNF) were calculated for all EMG signals. The barycenter of RMS values over the HD-EMG grid was also determined, as well as normalized mutual information (NMI) for each pair of muscles. Cycle-to-cycle variability of these metrics was also assessed. With time, EMG RMS increased for most of the muscles, and MNF decreased. Trapezius activity became higher on the lateral side than on the medial side of the HD-EMG grid and the barycenter moved in a lateral direction. NMI between muscle pairs increased with time while its variability decreased. The variability of the metrics during the initial 10 % of task performance was not associated with the time to task termination. Our results suggest that the considerable variability in force and posture contained in the dynamic task per se masks any possible effects of differences between subjects in initial motor variability on the rate of fatigue development.

  10. Stress-induced spatiotemporal variations in anisotropic structures beneath Hakone volcano, Japan, detected by S wave splitting: A tool for volcanic activity monitoring

    NASA Astrophysics Data System (ADS)

    Honda, Ryou; Yukutake, Yohei; Yoshida, Akio; Harada, Masatake; Miyaoka, Kazuki; Satomura, Mikio

    2014-09-01

    Hakone volcano, located at the northern tip of the Izu-Mariana volcanic arc, Japan, has a large caldera structure containing numerous volcanic hot springs. Earthquake swarms have occurred repeatedly within the caldera. The largest seismic swarm since the commencement of modern seismic observations (in 1968) occurred in 2001. We investigated the anisotropic structure of Hakone volcano based on S wave splitting analysis and found spatiotemporal changes in the splitting parameters accompanying the seismic swarm activity. Depth-dependent anisotropic structures are clearly observed. A highly anisotropic layer with a thickness of ~1.5 km is located beneath the Koziri (KZR) and Kozukayama (KZY) stations. The anisotropic intensity in the region reaches a maximum of 6-7% at a depth of 1 km and decreases markedly to less than 1% at a depth of 2 km. The anisotropic intensity beneath Komagatake station (KOM) decreases gradually from a maximum of 6% at the surface to 0% at a depth of 5 km but is still greater than 2.5% at a depth of 3 km. At KZY, the anisotropic intensity along a travel path of which the back azimuth was the south decreased noticeably after the 2001 seismic swarm activity. During the swarm activity, tilt meters and GPS recorded the crustal deformation. The observed decrease in anisotropic intensity is presumed to be caused by the closing of microcracks by stress changes accompanying crustal deformation near the travel path.

  11. Physico-chemical characteristics and methanogen communities in swine and dairy manure storage tanks: spatio-temporal variations and impact on methanogenic activity.

    PubMed

    Barret, Maialen; Gagnon, Nathalie; Topp, Edward; Masse, Lucie; Massé, Daniel I; Talbot, Guylaine

    2013-02-01

    Greenhouse gas emissions represent a major environmental problem associated with the management of manure from the livestock industry. Methane is the primary GHG emitted during manure outdoor storage. In this paper, the variability of two swine and two dairy manure storage tanks was surveyed, in terms of physico-chemical and microbiological parameters. The impact of the inter-tank and spatio-temporal variations of these parameters on the methanogenic activity of manure was ascertained. A Partial Least Square regression was carried out, which demonstrated that physico-chemical as well as microbiological parameters had a major influence on the methanogenic activity. Among the 19 parameters included in the regression, the concentrations of VFAs had the strongest negative influence on the methane emission rate of manure, resulting from their well-known inhibitory effect. The relative abundance of two amplicons in archaeal fingerprints was found to positively influence the methanogenic activity, suggesting that Methanoculleus spp. and possibly Methanosarcina spp. are major contributors to methanogenesis in storage tanks. This work gave insights into the mechanisms, which drive methanogenesis in swine and dairy manure storage tanks.

  12. Spatio-temporal clustering

    NASA Astrophysics Data System (ADS)

    Kisilevich, Slava; Mansmann, Florian; Nanni, Mirco; Rinzivillo, Salvatore

    Spatio-temporal clustering is a process of grouping objects based on their spatial and temporal similarity. It is relatively new subfield of data mining which gained high popularity especially in geographic information sciences due to the pervasiveness of all kinds of location-based or environmental devices that record position, time or/and environmental properties of an object or set of objects in real-time. As a consequence, different types and large amounts of spatio-temporal data became available that introduce new challenges to data analysis and require novel approaches to knowledge discovery. In this chapter we concentrate on the spatio-temporal clustering in geographic space. First, we provide a classification of different types of spatio-temporal data. Then, we focus on one type of spatio-temporal clustering - trajectory clustering, provide an overview of the state-of-the-art approaches and methods of spatio-temporal clustering and finally present several scenarios in different application domains such as movement, cellular networks and environmental studies.

  13. Spatio-temporal analysis reveals active control of both task-relevant and task-irrelevant variables

    PubMed Central

    Rácz, Kornelius; Valero-Cuevas, Francisco J.

    2013-01-01

    redundancy. Instead of a dichotomy of presence vs. absence of control, we should speak of a continuum of weaker to stronger—and potentially different—control strategies in specific spatiotemporal domains, indicated here by the magnitude of deviation from the 0.5 scaling exponent. Moreover, these results are counter examples to the UCM hypothesis and the Minimal Intervention principle, and the similar nature of control actions across time scales in both task-relevant and task-irrelevant spaces points to a level of modularity not previously recognized. PMID:24312045

  14. Code System to Detect Recurring Loss of Special Nuclear Materials.

    SciTech Connect

    PICARD, R. R.

    2001-08-23

    Version 00 NRCPAGE is used in safeguards applications to detect a recurring loss of special nuclear material by frequent evaluation (sequential analysis) of accountability data. Standard sequential testing procedures are traditionally based on sequences of independent and normally distributed measurements. This same approach can be applied to materials balance (MB) data. Here, the term materials balance has a meaning similar to inventory difference and represents a materials loss indicator localized in time and space. However, distinct Mbs cannot be reasonably treated as statistically independent and may not always be reasonably treated as normally distributed. Furthermore, the covariance structure associated with a given MB sequence is not known and must be estimated. Nonindependence is treated by converting the MB sequence to the innovation sequence, sometimes called the ITMUF sequence or the sequence of MUF residuals, which are statistically independent and amenable to sequential test procedures. A one-sided page's test, effective for a wide range of recurring loss scenarios, is applied to the standardized innovation sequence. The program can be easily modified to suit particular needs; the models for the assumption of multivariate normality for MBs when computing the innovation sequence or the test procedure can be changed as can the input/output format, dimensioning, local error checking, and simulation work. Input files can be sequentially constructed using local text editors to update existing files. Output files can be read by graphics, report writer, or other stand-alone utility routines.

  15. Adult Rhabdomyosarcoma of Ethmoid Sinus Recurring as an Orbital Mass

    PubMed Central

    Eshraghi, Bahram; Ameli, Kambiz

    2016-01-01

    Alveolar rhabdomyosarcoma (RMS) is a primitive, malignant, round cell neoplasm derived from mesenchymal tissue that exhibits partial skeletal muscle differentiation. We describe a rare case of alveolar RMS of ethmoid sinus, recurring as an orbital mass. A 23-year-old man with the chief complaint of anosmia and mild proptosis was diagnosed with RMS of the left ethmoid sinus and orbit following an endoscopic biopsy of the mass. He was treated with chemotherapy and radiotherapy. At 12 months after diagnosis, while still on maintenance chemotherapy, he presented to our eye hospital with a large medial canthal mass and lateral globe displacement. Orbital computed tomography revealed an extraconal mass in the medial orbit of the left eye, extending posteriorly and compressing the medial rectus muscle. Notably, the ethmoid sinus was clear. Incisional biopsy was performed and the recurrence of alveolar RMS was confirmed. Alveolar RMS of the ethmoid sinus may recur as an orbital mass, even if the sinus where it originated is clear at the time of recurrence. PMID:27190854

  16. Spatio-temporal co-ordination of RhoA, Rac1 and Cdc42 activation during prototypical edge protrusion and retraction dynamics

    PubMed Central

    Martin, Katrin; Reimann, Andreas; Fritz, Rafael D.; Ryu, Hyunryul; Jeon, Noo Li; Pertz, Olivier

    2016-01-01

    The three canonical Rho GTPases RhoA, Rac1 and Cdc42 co-ordinate cytoskeletal dynamics. Recent studies indicate that all three Rho GTPases are activated at the leading edge of motile fibroblasts, where their activity fluctuates at subminute time and micrometer length scales. Here, we use a microfluidic chip to acutely manipulate fibroblast edge dynamics by applying pulses of platelet-derived growth factor (PDGF) or the Rho kinase inhibitor Y-27632 (which lowers contractility). This induces acute and robust membrane protrusion and retraction events, that exhibit stereotyped cytoskeletal dynamics, allowing us to fairly compare specific morphodynamic states across experiments. Using a novel Cdc42, as well as previously described, second generation RhoA and Rac1 biosensors, we observe distinct spatio-temporal signaling programs that involve all three Rho GTPases, during protrusion/retraction edge dynamics. Our results suggest that Rac1, Cdc42 and RhoA regulate different cytoskeletal and adhesion processes to fine tune the highly plastic edge protrusion/retraction dynamics that power cell motility. PMID:26912264

  17. Fibrin Networks Support Recurring Mechanical Loads by Adapting their Structure across Multiple Scales.

    PubMed

    Kurniawan, Nicholas A; Vos, Bart E; Biebricher, Andreas; Wuite, Gijs J L; Peterman, Erwin J G; Koenderink, Gijsje H

    2016-09-06

    Tissues and cells sustain recurring mechanical loads that span a wide range of loading amplitudes and timescales as a consequence of exposure to blood flow, muscle activity, and external impact. Both tissues and cells derive their mechanical strength from fibrous protein scaffolds, which typically have a complex hierarchical structure. In this study, we focus on a prototypical hierarchical biomaterial, fibrin, which is one of the most resilient naturally occurring biopolymers and forms the structural scaffold of blood clots. We show how fibrous networks composed of fibrin utilize irreversible changes in their hierarchical structure at different scales to maintain reversible stress stiffening up to large strains. To trace the origin of this paradoxical resilience, we systematically tuned the microstructural parameters of fibrin and used a combination of optical tweezers and fluorescence microscopy to measure the interactions of single fibrin fibers for the first time, to our knowledge. We demonstrate that fibrin networks adapt to moderate strains by remodeling at the network scale through the spontaneous formation of new bonds between fibers, whereas they adapt to high strains by plastic remodeling of the fibers themselves. This multiscale adaptation mechanism endows fibrin gels with the remarkable ability to sustain recurring loads due to shear flows and wound stretching. Our findings therefore reveal a microscopic mechanism by which tissues and cells can balance elastic nonlinearity and plasticity, and thus can provide microstructural insights into cell-driven remodeling of tissues.

  18. Finite-element models on spatiotemporal variations in intraplate seismicity caused by postglacial unloading and rebound: Implications for active normal faults in the Basin and Range Province

    NASA Astrophysics Data System (ADS)

    Karow, T.; Hampel, A.

    2007-12-01

    The actively extending Basin and Range Province was covered by numerous pluvial lakes and glaciers on several of the higher ranges during the Last Glacial Maximum (Osburn and Bevis, QSR, 2001). The largest lakes were Lake Bonneville and Lake Lahontan, located in the eastern and western parts of the Basin and Range Province, respectively. Regression of these lakes at the end of last glacial period caused significant isostatic rebound of the lithosphere (Bills et al., JGR, 1994; Bills et al., JGR, 2007). The rebound associated with the regression of Lake Bonneville has been shown, using two-dimensional numerical models, to affect the stress field of the lithosphere and to cause a slip rate increase on the Wasatch normal fault (Hetzel and Hampel, Nature 2005). Here we use three-dimensional finite-element models of normal fault arrays to investigate spatiotemporal variations in the regional stress field and in the rate of normal faulting caused by glacial-interglacial variations of the surface load. Our models indicate that regression of Lake Lahontan but also of smaller lakes and glaciers alter the regional stress field and hence may ultimately affect the intraplate seismicity. Paleoseismological data from faults in the east-central and northern Basin and Range Province seem to support the idea of an increase in seismicity after the Last Glacial Maximum (Friedrich el al., JGR, 2003; Stickney and Bartholomew, BSSA, 1987; Wesnousky et al., JGR, 2005).

  19. Chaotic Dynamics of Flags from Recurring Values of Flapping Moment

    NASA Astrophysics Data System (ADS)

    Virot, Emmanuel; Faranda, Davide; Amandolese, Xavier; Hémon, Pascal

    The performance of recently proposed flag-based energy harvesters is strongly limited by the chaotic response of flags to strong winds. From an experimental point of view, the detection of flag chaotic dynamics were scarce, based on the flapping amplitude and the maximal Lyapunov exponent. In practice, tracking the flapping amplitude is difficult and flawed in the large oscillation limit. Also, computing the maximal Lyapunov exponent from time series of limited size requires strong assumptions on the attractor geometry, without getting insurance of their reliability. For bypassing these issues, (1) we use a time series which takes into account the whole dynamics of the flag, by using the flapping moment which integrates its displacements, and (2) we apply an algorithm of detection of chaos based on recurring values in time series.

  20. Building resilience to face recurring environmental crisis in African Sahel

    NASA Astrophysics Data System (ADS)

    Boyd, Emily; Cornforth, Rosalind J.; Lamb, Peter J.; Tarhule, Aondover; Lélé, M. Issa; Brouder, Alan

    2013-07-01

    The present food shortages in the Horn of Africa and the West African Sahel are affecting 31 million people. Such continuing and future crises require that people in the region adapt to an increasing and potentially irreversible global sustainability challenge. Given this situation and that short-term weather and seasonal climate forecasting have limited skill for West Africa, the Rainwatch project illustrates the value of near real-time monitoring and improved communication for the unfavourable 2011 West African monsoon, the resulting severe drought-induced humanitarian impacts continuing into 2012, and their exacerbation by flooding in 2012. Rainwatch is now coupled with a boundary organization (Africa Climate Exchange, AfClix) with the aim of integrating the expertise and actions of relevant institutions, agencies and stakeholders to broker ground-based dialogue to promote resilience in the face of recurring crisis.

  1. Recurred Post-intubation Tracheal Stenosis Treated with Bronchoscopic Cryotherapy

    PubMed Central

    Jung, Ye-Ryung; Taek Jeong, Joon; Kyu Lee, Myoung; Kim, Sang-Ha; Joong Yong, Suk; Jeong Lee, Seok; Lee, Won-Yeon

    2016-01-01

    Post-intubation tracheal stenosis accounts for the greatest proportion of whole-cause tracheal stenosis. Treatment of post-intubation tracheal stenosis requires a multidisciplinary approach. Surgery or an endoscopic procedure can be used, depending on the type of stenosis. However, the efficacy of cryotherapy in post-intubation tracheal stenosis has not been validated. Here, we report a case of recurring post-intubation tracheal stenosis successfully treated with bronchoscopic cryotherapy that had previously been treated with surgery. In this case, cryotherapy was effective in treating web-like fibrous stenosis, without requiring more surgery. Cryotherapy can be considered as an alternative or primary treatment for post-intubation tracheal stenosis. PMID:27853078

  2. Failure of flat warts to recur in electrosurgically altered skin.

    PubMed

    Berman, A

    1978-12-01

    Two men with recurring flat warts in the beard area have been observed for five and ten years, respectively. Both have depigmented patches at sites where flat warts had been removed by electrosurgical destruction. Crops of new warts appear periodically. These develop always on the normally pigmented skin and have never been found in the leukodermic areas. Flat warts have been observed repeatedly at the margin of depigmented and normal skin; these invariably enlarge toward the normal skin and never encroach on leukodermic skin. The failure of flat warts to develop in electrosurgically treated skin, if substantiated, would indicate that local tissue factors influence resistance to development of flat warts. Perhaps this phenomenon is similar to that reported in Darier's disease, where partial-thickness excision of involved skin has resulted in resistance to recurrent disease.

  3. Recurring patterns in bacterioplankton dynamics during coastal spring algae blooms

    PubMed Central

    Teeling, Hanno; Fuchs, Bernhard M; Bennke, Christin M; Krüger, Karen; Chafee, Meghan; Kappelmann, Lennart; Reintjes, Greta; Waldmann, Jost; Quast, Christian; Glöckner, Frank Oliver; Lucas, Judith; Wichels, Antje; Gerdts, Gunnar; Wiltshire, Karen H; Amann, Rudolf I

    2016-01-01

    A process of global importance in carbon cycling is the remineralization of algae biomass by heterotrophic bacteria, most notably during massive marine algae blooms. Such blooms can trigger secondary blooms of planktonic bacteria that consist of swift successions of distinct bacterial clades, most prominently members of the Flavobacteriia, Gammaproteobacteria and the alphaproteobacterial Roseobacter clade. We investigated such successions during spring phytoplankton blooms in the southern North Sea (German Bight) for four consecutive years. Dense sampling and high-resolution taxonomic analyses allowed the detection of recurring patterns down to the genus level. Metagenome analyses also revealed recurrent patterns at the functional level, in particular with respect to algal polysaccharide degradation genes. We, therefore, hypothesize that even though there is substantial inter-annual variation between spring phytoplankton blooms, the accompanying succession of bacterial clades is largely governed by deterministic principles such as substrate-induced forcing. DOI: http://dx.doi.org/10.7554/eLife.11888.001 PMID:27054497

  4. Patterns of spatio-temporal correlations in the neural activity of the cat motor cortex during trained forelimb movements.

    PubMed

    Ghosh, Soumya; Putrino, David; Burro, Bianca; Ring, Alexander

    2009-06-01

    In order to study how neurons in the primary motor cortex (MI) are dynamically linked together during skilled movement, we recorded simultaneously from many cortical neurons in cats trained to perform a reaching and retrieval task using their forelimbs. Analysis of task-related spike activity in the MI of the hemisphere contralateral to the reaching forelimb (in identified forelimb or hindlimb representations) recorded through chronically implanted microwires, was followed by pairwise evaluation of temporally correlated activity in these neurons during task performance using shuffle corrected cross-correlograms. Over many months of recording, a variety of task-related modulations of neural activities were observed in individual efferent zones. Positively correlated activity (mainly narrow peaks at zero or short latencies) was seen during task performance frequently between neurons recorded within the forelimb representation of MI, rarely within the hindlimb area of MI, and never between forelimb and hindlimb areas. Correlated activity was frequently observed between neurons with different patterns of task-related activity or preferential activity during different task elements (reaching, feeding, etc.), and located in efferent zones with dissimilar representation as defined by intracortical microstimulation. The observed synchronization of action potentials among selected but functionally varied groups of MI neurons possibly reflects dynamic recruitment of network connections between efferent zones during skilled movement.

  5. Spatio-temporal variation and seasonality of Odontocetes' foraging activity in the leeward side of the island of Hawaii

    NASA Astrophysics Data System (ADS)

    Giorli, Giacomo; Au, Whitlow W. L.

    2017-03-01

    The Kona coast of the island of Hawaii hosts many species of odontocetes. These marine mammals are top predators and their foraging activity plays an important role in the ecosystem dynamics. Three passive acoustics recorders were used to study the temporal and spatial occurrence of the foraging activity of odontocetes (excluding beaked and sperm whales) at three locations along the Kona coast of Hawaii between 2012 and 2013. Echolocation clicks were detected using the M3R1

  6. 78 FR 48802 - Safety Zones; Recurring Events in Captain of the Port Duluth Zone

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-12

    ... Island fireworks, and other historically recurring marine events, including the Lake Superior Dragon Boat...) Lake Superior Dragon Boat Festival Fireworks; Superior, WI. (i) Location. All waters of Superior...

  7. [Spatio-Temporal Bioelectrical Brain Activity Organization during Reading Syntagmatic and Paradigmatic Collocations by Students with Different Foreign Language Proficiency].

    PubMed

    Sokolova, L V; Cherkasova, A S

    2015-01-01

    Texts or words/pseudowords are often used as stimuli for human verbal activity research. Our study pays attention to decoding processes of grammatical constructions consisted of two-three words--collocations. Russian and English collocation sets without any narrative were presented to Russian-speaking students with different English language skill. Stimulus material had two types of collocations: paradigmatic and syntagmatic. 30 students (average age--20.4 ± 0.22) took part in the study, they were divided into two equal groups depending on their English language skill (linguists/nonlinguists). During reading brain bioelectrical activity of cortex has been registered from 12 electrodes in alfa-, beta-, theta-bands. Coherent function reflecting cooperation of different cortical areas during reading collocations has been analyzed. Increase of interhemispheric and diagonal connections while reading collocations in different languages in the group of students with low knowledge of foreign language testifies of importance of functional cooperation between the hemispheres. It has been found out that brain bioelectrical activity of students with good foreign language knowledge during reading of all collocation types in Russian and English is characterized by economization of nervous substrate resources compared to nonlinguists. Selective activation of certain cortical areas has also been observed (depending on the grammatical construction type) in nonlinguists group that is probably related to special decoding system which processes presented stimuli. Reading Russian paradigmatic constructions by nonlinguists entailed increase between left cortical areas, reading of English syntagmatic collocations--between right ones.

  8. Single-trial analysis of cortical oscillatory activities during voluntary movements using empirical mode decomposition (EMD)-based spatiotemporal approach.

    PubMed

    Lee, Po-Lei; Shang, Li-Zen; Wu, Yu-Te; Shu, Chih-Hung; Hsieh, Jen-Chuen; Lin, Yung-Yang; Wu, Chi-Hsun; Liu, Yu-Lu; Yang, Chia-Yen; Sun, Chia-Wei; Shyu, Kuo-Kai

    2009-08-01

    This study presents a method based on empirical mode decomposition (EMD) and a spatial template-based matching approach to extract sensorimotor oscillatory activities from multi-channel magnetoencephalographic (MEG) measurements during right index finger lifting. The longitudinal gradiometer of the sensor unit which presents most prominent SEF was selected on which each single-trial recording was decomposed into a set of intrinsic mode functions (IMFs). The correlation between each IMF of the selected channel and raw data on other channels were created and represented as a spatial map. The sensorimotor-related IMFs with corresponding correlational spatial map exhibiting large values on primary sensorimotor area (SMI) were selected via spatial-template matching process. Trial-specific alpha and beta bands were determined in sensorimotor-related oscillatory activities using a two-spectrum comparison between the spectra obtained from baseline period (-4 to -3 s) and movement-onset period (-0.5 to 0.5 s). Sensorimotor-related oscillatory activities were filtered within the trial-specific frequency bands to resolve task-related oscillatory activities. Results demonstrated that the optimal phase and amplitude information were preserved not only for alpha suppression (event-related desynchronization) and beta rebound (event-related synchronization) but also for profound analysis of subtle dynamics across trials. The retention of high SNR in the extracted oscillatory activities allow various methods of source estimation that can be applied to study the intricate brain dynamics of motor control mechanisms. The present study enables the possibility of investigating cortical pathophysiology of movement disorder on a trial-by-trial basis which also permits an effective alternative for participants or patients who can not endure lengthy procedures or are incapable of sustaining long experiments.

  9. Genetic instability is prevented by Mrc1-dependent spatio-temporal separation of replicative and repair activities of homologous recombination

    PubMed Central

    Prado, Félix

    2014-01-01

    Homologous recombination (HR) is required to protect and restart stressed replication forks. Paradoxically, the Mrc1 branch of the S phase checkpoints, which is activated by replicative stress, prevents HR repair at breaks and arrested forks. Indeed, the mechanisms underlying HR can threaten genome integrity if not properly regulated. Thus, understanding how cells avoid genetic instability associated with replicative stress, a hallmark of cancer, is still a challenge. Here I discuss recent results that support a model by which HR responds to replication stress through replicative and repair activities that operate at different stages of the cell cycle (S and G2, respectively) and in distinct subnuclear structures. Remarkably, the replication checkpoint appears to control this scenario by inhibiting the assembly of HR repair centers at stressed forks during S phase, thereby avoiding genetic instability. PMID:24615940

  10. Spatio-temporal imaging of EGF-induced activation of protein kinase A by FRET in living cells

    NASA Astrophysics Data System (ADS)

    Wang, Jin Jun; Chen, Xiao-Chuan; Xing, Da

    2004-07-01

    Intracellular molecular interaction is important for the study of cell physiology, yet current relevant methods require fixation or microinjection and lack temporal or spatial resolution. We introduced a new method -- fluorescence resonance energy transfer (FRET) to detect molecular interaction in living cells. On the basis of FRET principle, A-kinase activity reporter (AKAR) protein was designed to consist of the fusions of cyan fluorescent protein (CFP), a phosphoamino acid binding domain, a consensus substrate for protein kinase-A (PKA), and yellow fluorescent protein (YFP). In this study, the designed pAKAR plasmid was used to transfect a human lung cancer cell line (ASTC-a-1). When the AKAR-transfected cells were treated by forskolin (Fsk), we were able to observe the efficient transfer of energy from excited CFP to YFP within the AKAR molecule by fluorescence microcopy, whereas no FRET was detected in the transfected cells without the treatment of Fsk. When the cells were treated by Epidermal growth factor (EGF), the change of FRET was observed at different subcellular locations, reflecting PKA activation inside the cells upon EGF stimulation. The successful design of a fluorescence reporter of PKA activation and its application demonstrated the superiority of this technology in the research of intracellular protein-protein interaction.

  11. Frequency-dependent spatiotemporal profiles of visual responses recorded with subdural ECoG electrodes in awake monkeys: Differences between high- and low-frequency activity.

    PubMed

    Takaura, Kana; Tsuchiya, Naotsugu; Fujii, Naotaka

    2016-01-01

    Electrocorticography (ECoG) constitutes a powerful and promising neural recording modality in humans and animals. ECoG signals are often decomposed into several frequency bands, among which the so-called high-gamma band (80-250Hz) has been proposed to reflect local cortical functions near the cortical surface below the ECoG electrodes. It is typically assumed that the lower the frequency bands, the lower the spatial resolution of the signals; thus, there is not much to gain by analyzing the event-related changes of the ECoG signals in the lower-frequency bands. However, differences across frequency bands have not been systematically investigated. To address this issue, we recorded ECoG activity from two awake monkeys performing a retinotopic mapping task. We characterized the spatiotemporal profiles of the visual responses in the time-frequency domain. We defined the preferred spatial position, receptive field (RF), and response latencies of band-limited power (BLP) (i.e., alpha [3.9-11.7Hz], beta [15.6-23.4Hz], low [30-80Hz] and high [80-250Hz] gamma) for each electrode and compared them across bands and time-domain visual evoked potentials (VEPs). At the population level, we found that the spatial preferences were comparable across bands and VEPs. The high-gamma power showed a smaller RF than the other bands and VEPs. The response latencies for the alpha band were always longer than the latencies for the other bands and fastest in VEPs. Comparing the response profiles in both space and time for each cortical region (V1, V4+, and TEO/TE) revealed regional idiosyncrasies. Although the latencies of visual responses in the beta, low-, and high-gamma bands were almost identical in V1 and V4+, beta and low-gamma BLP occurred about 17ms earlier than high-gamma power in TEO/TE. Furthermore, TEO/TE exhibited a unique pattern in the spatial response profile: the alpha and high-gamma responses tended to prefer the foveal regions, whereas the beta and low-gamma responses

  12. Potential of two submontane broadleaved species (Acer opalus, Quercus pubescens) to reveal spatiotemporal patterns of rockfall activity

    NASA Astrophysics Data System (ADS)

    Favillier, Adrien; Lopez-Saez, Jérôme; Corona, Christophe; Trappmann, Daniel; Toe, David; Stoffel, Markus; Rovéra, Georges; Berger, Frédéric

    2015-10-01

    Long-term records of rockfalls have proven to be scarce and typically incomplete, especially in increasingly urbanized areas where inventories are largely absent and the risk associated with rockfall events rises proportionally with urbanization. On forested slopes, tree-ring analyses may help to fill this gap, as they have been demonstrated to provide annually-resolved data on past rockfall activity over long periods. Yet, the reconstruction of rockfall chronologies has been hampered in the past by the paucity of studies that include broadleaved tree species, which are, in fact, quite common in various rockfall-prone environments. In this study, we test the sensitivity of two common, yet unstudied, broadleaved species - Quercus pubescens Willd. (Qp) and Acer opalus Mill. (Ao) - to record rockfall impacts. The approach is based on a systematic mapping of trees and the counting of visible scars on the stem surface of both species. Data are presented from a site in the Vercors massif (French Alps) where rocks are frequently detached from Valanginian limestone and marl cliffs. We compare recurrence interval maps obtained from both species and from two different sets of tree structures (i.e., single trees vs. coppice stands) based on Cohen's k coefficient and the mean absolute error. A total of 1230 scars were observed on the stem surface of 847 A. opalus and Q. pubescens trees. Both methods yield comparable results on the spatial distribution of relative rockfall activity with similar downslope decreasing recurrence intervals. Yet recurrence intervals vary significantly according to tree species and tree structure. The recurrence interval observed on the stem surface of Q. pubescens exceeds that of A. opalus by > 20 years in the lower part of the studied plot. Similarly, the recurrence interval map derived from A. opalus coppice stands, dominant at the stand scale, does not exhibit a clear spatial pattern. Differences between species may be explained by the bark

  13. Spatiotemporal relationships between the abundance, distribution, and potential activities of ammonia-oxidizing and denitrifying microorganisms in intertidal sediments.

    PubMed

    Smith, Jason M; Mosier, Annika C; Francis, Christopher A

    2015-01-01

    The primary objective of this study was to gain an understanding of how key microbial communities involved in nitrogen cycling in estuarine sediments vary over a 12-month period. Furthermore, we sought to determine whether changes in the size of these communities are related to, or indicative of, seasonal patterns in fixed nitrogen dynamics in Elkhorn Slough--a small, agriculturally impacted estuary with a direct connection to Monterey Bay. We assessed sediment and pore water characteristics, abundance of functional genes for nitrification (bacterial and archaeal amoA, encoding ammonia monooxygenase subunit A) and denitrification (nirS and nirK, encoding nitrite reductase), and measurements of potential nitrification and denitrification activities at six sites. No seasonality in the abundance of denitrifier or ammonia oxidizer genes was observed. A strong association between potential nitrification activity and the size of ammonia-oxidizing bacterial communities was observed across the estuary. In contrast, ammonia-oxidizing archaeal abundances remained relatively constant in space and time. Unlike many other estuaries, salinity does not appear to regulate the distribution of ammonia-oxidizing communities in Elkhorn Slough. Instead, their distributions appear to be governed over two different time scales. Long-term niche characteristics selected for the gross size of archaeal and bacterial ammonia-oxidizing communities, yet covariation in their abundances between monthly samples suggests that they respond in a similar manner to short-term changes in their environment. Abundances of denitrifier and ammonia oxidizer genes also covaried, but site-specific differences in this relationship suggest differing levels of interaction (or coupling) between nitrification and denitrification.

  14. Collective synchronization of self/non-self discrimination in T cell activation, across multiple spatio-temporal scales

    NASA Astrophysics Data System (ADS)

    Altan-Bonnet, Gregoire

    The immune system is a collection of cells whose function is to eradicate pathogenic infections and malignant tumors while protecting healthy tissues. Recent work has delineated key molecular and cellular mechanisms associated with the ability to discriminate self from non-self agents. For example, structural studies have quantified the biophysical characteristics of antigenic molecules (those prone to trigger lymphocyte activation and a subsequent immune response). However, such molecular mechanisms were found to be highly unreliable at the individual cellular level. We will present recent efforts to build experimentally validated computational models of the immune responses at the collective cell level. Such models have become critical to delineate how higher-level integration through nonlinear amplification in signal transduction, dynamic feedback in lymphocyte differentiation and cell-to-cell communication allows the immune system to enforce reliable self/non-self discrimination at the organism level. In particular, we will present recent results demonstrating how T cells tune their antigen discrimination according to cytokine cues, and how competition for cytokine within polyclonal populations of cells shape the repertoire of responding clones. Additionally, we will present recent theoretical and experimental results demonstrating how competition between diffusion and consumption of cytokines determine the range of cell-cell communications within lymphoid organs. Finally, we will discuss how biochemically explicit models, combined with quantitative experimental validation, unravel the relevance of new feedbacks for immune regulations across multiple spatial and temporal scales.

  15. Planktonic food web structure at a coastal time-series site: II. Spatiotemporal variability of microbial trophic activities

    NASA Astrophysics Data System (ADS)

    Connell, Paige E.; Campbell, Victoria; Gellene, Alyssa G.; Hu, Sarah K.; Caron, David A.

    2017-03-01

    The grazing activities of phagotrophic protists on various microbial assemblages play key roles in determining the amount of carbon available for higher trophic levels and for export out of the photic zone. However, comparisons of the proportion of carbon consumed from the phytoplankton (cyanobacteria+photosynthetic eukaryotes) and heterotrophic bacteria (bacteria+archaea, excluding cyanobacteria) are rare. In this study, microbial community composition, phytoplankton growth and mortality rates (total chlorophyll a, Synechococcus, Prochlorococcus, and photosynthetic picoeukaryotes), and bacterial mortality rates were measured seasonally from 2012 to 2014 in the surface waters of three environmentally distinct sites in the San Pedro Channel, off the coast of southern CA, USA. Higher nutrient concentrations at the nearshore site supported community standing stocks that were 1.3-4.5x those found offshore, yet average growth and grazing rates of the phytoplankton and bacterial assemblages were generally similar between sites and across seasons. Thus, the amount of carbon consumed by the grazer assemblage was largely dictated by prey standing stocks. Heterotrophic bacteria constituted an important source of carbon for microbial consumers, particularly at the two offshore sites where bacterial carbon consumed was roughly equivalent to the amount of phytoplankton carbon consumed. Carbon removal by grazers at the nearshore station was predominantly from the diatoms, which were the primary component of the photosynthetic community at that site. This study highlights the significant contribution of protistan-bacterial trophic interactions to planktonic food webs and provides unique community composition and turnover data to inform biogeochemical models.

  16. The water content of recurring slope lineae on Mars

    USGS Publications Warehouse

    Edwards, Christopher S.; Piqueux, Sylvain

    2016-01-01

    Observations of recurring slope lineae (RSL) from the High-Resolution Imaging Science Experiment have been interpreted as present-day, seasonally variable liquid water flows; however, orbital spectroscopy has not confirmed the presence of liquid H2O, only hydrated salts. Thermal Emission Imaging System (THEMIS) temperature data and a numerical heat transfer model definitively constrain the amount of water associated with RSL. Surface temperature differences between RSL-bearing and dry RSL-free terrains are consistent with no water associated with RSL and, based on measurement uncertainties, limit the water content of RSL to at most 0.5–3 wt %. In addition, distinct high thermal inertia regolith signatures expected with crust-forming evaporitic salt deposits from cyclical briny water flows are not observed, indicating low water salinity (if any) and/or low enough volumes to prevent their formation. Alternatively, observed salts may be preexisting in soils at low abundances (i.e., near or below detection limits) and largely immobile. These RSL-rich surfaces experience ~100 K diurnal temperature oscillations, possible freeze/thaw cycles and/or complete evaporation on time scales that challenge their habitability potential. The unique surface temperature measurements provided by THEMIS are consistent with a dry RSL hypothesis or at least significantly limit the water content of Martian RSL.

  17. Recurring middle Pleistocene outburst floods in east-central Alaska

    USGS Publications Warehouse

    Froese, D.G.; Smith, D.G.; Westgate, J.A.; Ager, T.A.; Preece, S.J.; Sandhu, A.; Enkin, R.J.; Weber, F.

    2003-01-01

    Recurring glacial outburst floods from the Yukon-Tanana Upland are inferred from sediments exposed along the Yukon River near the mouth of Charley River in east-central Alaska. Deposits range from imbricate gravel and granules indicating flow locally extending up the Yukon valley, to more distal sediments consisting of at least 10 couplets of planar sands, granules, and climbing ripples with up-valley paleocurrent indicators overlain by massive silt. An interglacial organic silt, occurring within the sequence, indicates at least two flood events are associated with an earlier glaciation, and at least three flood events are associated with a later glaciation which postdates the organic silt. A minimum age for the floods is provided by a glass fission track age of 560,000 ?? 80,000 yr on the GI tephra, which occurs 8 m above the flood beds. A maximum age of 780,000 yr for the floods is based on normal magnetic polarity of the sediments. These age constraints allow us to correlate the flood events to the early-middle Pleistocene. And further, the outburst floods indicate extensive glaciation of the Yukon-Tanana Upland during the early-middle Pleistocene, likely representing the most extensive Pleistocene glaciation of the area. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  18. The water content of recurring slope lineae on Mars

    NASA Astrophysics Data System (ADS)

    Edwards, Christopher S.; Piqueux, Sylvain

    2016-09-01

    Observations of recurring slope lineae (RSL) from the High-Resolution Imaging Science Experiment have been interpreted as present-day, seasonally variable liquid water flows; however, orbital spectroscopy has not confirmed the presence of liquid H2O, only hydrated salts. Thermal Emission Imaging System (THEMIS) temperature data and a numerical heat transfer model definitively constrain the amount of water associated with RSL. Surface temperature differences between RSL-bearing and dry RSL-free terrains are consistent with no water associated with RSL and, based on measurement uncertainties, limit the water content of RSL to at most 0.5-3 wt %. In addition, distinct high thermal inertia regolith signatures expected with crust-forming evaporitic salt deposits from cyclical briny water flows are not observed, indicating low water salinity (if any) and/or low enough volumes to prevent their formation. Alternatively, observed salts may be preexisting in soils at low abundances (i.e., near or below detection limits) and largely immobile. These RSL-rich surfaces experience ~100 K diurnal temperature oscillations, possible freeze/thaw cycles and/or complete evaporation on time scales that challenge their habitability potential. The unique surface temperature measurements provided by THEMIS are consistent with a dry RSL hypothesis or at least significantly limit the water content of Martian RSL.

  19. Recurring flares from supermassive black hole binaries: implications for tidal disruption candidates and OJ 287

    NASA Astrophysics Data System (ADS)

    Tanaka, Takamitsu L.

    2013-09-01

    I discuss the possibility that accreting supermassive black hole (SMBH) binaries with sub-parsec separations produce periodically recurring luminous outbursts that interrupt periods of relative quiescence. This hypothesis is motivated by two characteristics found generically in simulations of binaries embedded in prograde accretion discs: (i) the formation of a central, low-density cavity around the binary and (ii) the leakage of gas into this cavity, occurring once per orbit via discrete streams on nearly radial trajectories. The first feature would reduce the emergent optical/UV flux of the system relative to active galactic nuclei powered by a single SMBH, while the second can trigger quasi-periodic fluctuations in luminosity. I argue that the quasi-periodic accretion signature may be much more dramatic than previously thought, because the infalling gas streams can strongly shock-heat via self-collision and tidal compression, thereby enhancing viscous accretion. Any optically thick gas that is circularized about either SMBH can accrete before the next pair of streams is deposited, fuelling transient, luminous flares that recur every orbit. Due to the diminished flux in between accretion episodes, such cavity-accretion flares could plausibly be mistaken for the tidal disruptions of stars in quiescent nuclei. The flares could be distinguished from tidal disruption events if their quasi-periodic recurrence is observed, or if they are produced by very massive (≳109 M⊙) SMBHs that cannot disrupt solar-type stars. They may be discovered serendipitously in surveys such as LSST or eROSITA. I present a heuristic toy model as a proof of concept for the production of cavity-accretion flares, and generate mock light curves and spectra. I also apply the model to the active galaxy OJ 287, whose production of quasi-periodic pairs of optical flares has long fuelled speculation that it hosts an SMBH binary.

  20. The Recurring Author: William Shakespeare, a Case Study through Content Analysis.

    ERIC Educational Resources Information Center

    Harrison, Robert L., Jr.

    The "recurring author" is one whose works appear many times at different levels in instructional units found in literature textbook series. A descriptive case study discussed the treatment of a recurring author, William Shakespeare, using units in a sample of six literature textbook series. Developed to describe, to code, and to analyze…

  1. 77 FR 43511 - Special Local Regulations for Marine Events, Temporary Change of Dates for Recurring Marine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-25

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulations for Marine Events, Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, Wrightsville Channel... temporarily changing the enforcement period of one special local regulation for a recurring marine event...

  2. 77 FR 39453 - Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625--AA08 Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, Bogue Sound; Morehead City... regulation of a recurring marine event in the Fifth Coast Guard District. The proposed rule was initiated...

  3. 78 FR 77385 - Special Local Regulations and Safety Zones; Recurring Events in Northern New England

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-23

    ... Zones; Recurring Events in Northern New England AGENCY: Coast Guard, DHS. ACTION: Notice of proposed... marine events. When enforced, these proposed special local regulations and safety zones would restrict vessels from portions of water areas during certain annually recurring events. The proposed special...

  4. 76 FR 55561 - Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-08

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, Wrightsville Channel... temporarily change the enforcement period of one special local regulation for a recurring marine event in...

  5. Kindergarten Predictors of Recurring Externalizing and Internalizing Psychopathology in the Third and Fifth Grades

    ERIC Educational Resources Information Center

    Morgan, Paul L.; Farkas, George; Wu, Qiong

    2009-01-01

    This study evaluated the extent to which a range of risk factors (e.g., gender, race/ethnicity, low socioeconomic status) predicted kindergarten children's likelihood of later displaying recurring psychopathology. It used multilevel logistic regression to analyze teacher ratings of frequent and recurring externalizing and internalizing problem…

  6. 25 CFR 20.310 - What recurring income must be prorated?

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... AND SOCIAL SERVICES PROGRAMS Direct Assistance Determining Need and Income § 20.310 What recurring income must be prorated? The social services worker will prorate the following recurring income: (a... individuals employed on a contractual basis over the term of a contract; and (c) Intermittent income...

  7. Characteristics of the numerous and widespread recurring slope lineae (RSL) in Valles Marineris, Mars

    NASA Astrophysics Data System (ADS)

    Stillman, David E.; Michaels, Timothy I.; Grimm, Robert E.

    2017-03-01

    Recurring slope lineae (RSL) are narrow (0.5-5 m) dark features on Mars that incrementally lengthen down steep slopes, fade in colder seasons, and recur annually. These traits suggest that liquid water is flowing in the shallow subsurface of Mars today. Here we describe High Resolution Imaging Science Experiment (HiRISE) observations of RSL within Valles Marineris (VM). We have identified 239 candidate and confirmed RSL sites within all the major canyons of VM, with the exception of Echus Chasma. About half of all the globally known RSL locations occur within VM and the areal density of RSL on Coprates Montes appears to be the greatest on the planet. VM RSL are heterogeneously distributed, as they are primarily clustered in certain areas while being conspicuously absent in other locations that appear otherwise favorable. RSL have been found on many of the interior layered deposits (ILDs) within VM. Such ILD RSL appear to traverse bedrock, instead of regolith like all other RSL. Forty-six of the VM RSL sites show incremental lengthening and exhibit similar behavior in most of the canyons of VM, but the RSL duration at one site in Juventae Chasma is significantly reduced. Furthermore, the lengthening seasonality depends solely on slope orientation, with typical VM RSL on a given slope lengthening for ∼42-74% of a Mars year. There are always RSL lengthening within VM, regardless of the season. If RSL are caused by water, such a long active season at hundreds of VM RSL sites suggests that an appreciable source of water must be recharging these RSL. Thermophysical modeling indicates that a melting temperature range of ∼246 - 264 K is needed to reproduce the seasonal phenomenology of the VM RSL, suggesting the involvement of a brine consisting of tens of wt% salt. The mechanism(s) by which RSL are recharged annually remain uncertain. Overall, gaining a better understanding of how RSL form and recur can benefit the search for extant life on Mars and could provide

  8. Spatiotemporal Optical Vortices

    NASA Astrophysics Data System (ADS)

    Jhajj, N.; Larkin, I.; Rosenthal, E. W.; Zahedpour, S.; Wahlstrand, J. K.; Milchberg, H. M.

    2016-07-01

    We present the first experimental evidence, supported by theory and simulation, of spatiotemporal optical vortices (STOVs). A STOV is an optical vortex with phase and energy circulation in a spatiotemporal plane. Depending on the sign of the material dispersion, the local electromagnetic energy flow is saddle or spiral about the STOV. STOVs are a fundamental element of the nonlinear collapse and subsequent propagation of short optical pulses in material media, and conserve topological charge, constraining their birth, evolution, and annihilation. We measure a self-generated STOV consisting of a ring-shaped null in the electromagnetic field about which the phase is spiral, forming a dynamic torus that is concentric with and tracks the propagating pulse. Our results, here obtained for optical pulse collapse and filamentation in air, are generalizable to a broad class of nonlinearly propagating waves.

  9. Spatiotemporal multipartite entanglement

    SciTech Connect

    Kolobov, Mikhail I.; Patera, Giuseppe

    2011-05-15

    In this Rapid Communication, we propose, following the spirit of quantum imaging, to generalize the theory of multipartite entanglement for the continuous-variable Gaussian states by considering, instead of the global covariance matrix, the local correlation matrix at two different spatiotemporal points ({rho}-vector,t) and ({rho}-vector{sup '},t{sup '}), with {rho}-vector being the transverse coordinate. Our approach makes it possible to introduce the characteristic spatial length and the characteristic time of the multipartite entanglement, which in general depend on the number of 'parties' in the system. As an example, we consider tripartite entanglement in spontaneous parametric down-conversion with a spatially structured pump. We investigate spatiotemporal properties of such entanglement and calculate its characteristic spatial length and time.

  10. HiRISE observations of Recurring Slope Lineae (RSL) during southern summer on Mars

    USGS Publications Warehouse

    Ojha, Lujendra; McEwen, Alfred; Dundas, Colin; Byrne, Shane; Mattson, Sarah; Wray, James; Masse, Marion; Schaefer, Ethan

    2014-01-01

    Recurring Slope Lineae (RSL) are active features on Mars that might require flowing water. Most examples observed through 2011 formed on steep, equator-facing slopes in the southern mid-latitudes. They form and grow during warm seasons and fade and often completely disappear during colder seasons, but recur over multiple Mars years. They are recognizable by their incremental growth, relatively low albedo and downhill orientation. We examined all images acquired by HiRISE during Ls 250–10° (slightly longer than southern summer, Ls 270–360°) of Mars years 30–31 (03/2011–10/2011), and supplemented our results with data from previous studies to better understand the geologic context and characteristics of RSL. We also confirmed candidate and likely sites from previous studies and discovered new RSL sites. We report 13 confirmed RSL sites, including the 7 in McEwen et al. (McEwen et al. [2011]. Science 333(6043), 740–743]. The observed seasonality, latitudinal and slope orientation preferences, and THEMIS bright- ness temperatures indicate that RSL require warm temperatures to form. We conclude that RSL are a unique phenomenon on Mars, clearly distinct from other slope processes that occur at high latitudes associated with seasonal CO2 frost, and episodic mass wasting on equatorial slopes. However, only 41% (82 out of 200) of the sites that present apparently suitable conditions for RSL formation (steep, equator-facing rocky slopes with bedrock exposure) in the southern mid-latitudes (28–60°S) contain any candidate RSL, with confirmed RSL present only in 7% (13 sites) of those locations. Significant variability in abundance, size and exact location of RSL is also observed at most sites, indicating additional controls such as availability of water or salts that might be playing a crucial role.

  11. The impact of the uncertainty in the initial soil moisture condition of irrigated areas on the spatiotemporal characteristics of convective activity in Central Greece

    NASA Astrophysics Data System (ADS)

    Kotsopoulos, Stylianos; Ioannis, Tegoulias; Ioannis, Pytharoulis; Stergios, Kartsios; Dimitrios, Bampzelis; Theodore, Karacostas

    2015-04-01

    The region of Thessaly is the second largest plain in Greece and has a vital role in the financial life of the country, because of its significant agricultural production. The intensive and extensive cultivation of irrigated crops, in combination with the population increase and the alteration of precipitation patterns due to climate change, often leading the region to experience severe drought conditions, especially during the warm period of the year. The aim of the DAPHNE project is to tackle the problem of drought in this area by means of Weather Modification.In the framework of the project DAPHNE, the numerical weather prediction model WRF-ARW 3.5.1 is used to provide operational forecasts and hindcasts for the region of Thessaly. The goal of this study is to investigate the impact of the uncertainty in the initial soil moisture condition of irrigated areas, on the spatiotemporal characteristics of convective activity in the region of interest. To this end, six cases under the six most frequent synoptic conditions, which are associated with convective activity in the region of interest, are utilized, considering six different soil moisture initialization scenarios. In the first scenario (Control Run), the model is initialized with the surface soil moisture of the ECMWF analysis data, that usually does not take into account the modification of soil moisture due to agricultural activity in the area of interest. In the other five scenarios (Experiment 1,2,3,4,5) the soil moisture in the upper soil layers of the study area are modified from -50% to 50% of field capacity (-50%FC, -25%FC, FC, 25%FC, 50%FC),for the irrigated cropland.Three model domains, covering Europe, the Mediterranean Sea and northern Africa (d01), the wider area of Greece (d02) and central Greece - Thessaly region (d03) are used at horizontal grid-spacings of 15km, 5km and 1km respectively. ECMWF operational analyses at 6-hourly intervals (0.25ox0.25o lat.-long.) are imported as initial and

  12. Recurring Slope Lineae (RSL) and Future Exploration of Mars and Europa

    NASA Astrophysics Data System (ADS)

    McEwen, Alfred S.

    2014-11-01

    Recurring slope lineae (RSL) are narrow (<5 m), dark markings on steep (25°-40°) slopes that incrementally grow during warm seasons over low-albedo surfaces, fade when inactive, and recur over multiple Mars years. RSL often follow small gullies, but no topographic changes (with one exception) have been detected via 30 cm/pixel images from MRO/HiRISE. Mid-latitude RSL appear and lengthen in the late spring through summer favoring equator-facing slopes. RSL also occur in equatorial regions of Mars, especially in the deep canyons of Valles Marineris; some of these lineae are over 1 km long, again usually following pristine gullies. The fans on which many RSL terminate have distinctive color and spectral properties, but lack water absorption bands in MRO/CRISM. RSL are active at places with peak surface temperatures >250 K, but we do not know what time of day they are active. Laboratory experiments show that water or brines darken basaltic soils but produce weak water absorption bands after partial dehydration during the low-humidity middle afternoon conditions when MRO observes. The primary question is whether RSL are really due to water at or near the surface. All observations can be explained in this way, and no entirely dry model has been offered, but there is no direct detection of water. If they are due to water, where does the water come from and how is it replenished each year? Multiple hypotheses exist. RSL may be evidence for seepage of water today, and may mark the most promising sites to search for extraterrestrial life. There are 2 key unknowns: (1) Does the water originate from the subsurface where microbes would be protected from radiation, or does it have an atmospheric origin and is only skin deep? (2) Is the water too salty for life as we know it? RSL occur on steep, rocky slopes on which landing is dangerous, but several concepts for surface exploration of RSL were presented in http://www.lpi.usra.edu/meetings/marsconcepts2012/. Landing in RSL

  13. Statistical learning of recurring sound patterns encodes auditory objects in songbird forebrain.

    PubMed

    Lu, Kai; Vicario, David S

    2014-10-07

    Auditory neurophysiology has demonstrated how basic acoustic features are mapped in the brain, but it is still not clear how multiple sound components are integrated over time and recognized as an object. We investigated the role of statistical learning in encoding the sequential features of complex sounds by recording neuronal responses bilaterally in the auditory forebrain of awake songbirds that were passively exposed to long sound streams. These streams contained sequential regularities, and were similar to streams used in human infants to demonstrate statistical learning for speech sounds. For stimulus patterns with contiguous transitions and with nonadjacent elements, single and multiunit responses reflected neuronal discrimination of the familiar patterns from novel patterns. In addition, discrimination of nonadjacent patterns was stronger in the right hemisphere than in the left, and may reflect an effect of top-down modulation that is lateralized. Responses to recurring patterns showed stimulus-specific adaptation, a sparsening of neural activity that may contribute to encoding invariants in the sound stream and that appears to increase coding efficiency for the familiar stimuli across the population of neurons recorded. As auditory information about the world must be received serially over time, recognition of complex auditory objects may depend on this type of mnemonic process to create and differentiate representations of recently heard sounds.

  14. Spatiotemporal Regulation of Synaptic Vesicle Fusion Sites in Central Synapses.

    PubMed

    Maschi, Dario; Klyachko, Vitaly A

    2017-04-05

    The number and availability of vesicle release sites at the synaptic active zone (AZ) are critical factors governing neurotransmitter release; yet, these fundamental synaptic parameters have remained undetermined. Moreover, how neural activity regulates the spatiotemporal properties of the release sites within individual central synapses is unknown. Here, we combined a nanoscale imaging approach with advanced image analysis to detect individual vesicle fusion events with ∼27 nm localization precision at single hippocampal synapses under physiological conditions. Our results revealed the presence of multiple distinct release sites within individual hippocampal synapses. Release sites were distributed throughout the AZ and underwent repeated reuse. Furthermore, the spatiotemporal properties of the release sites were activity dependent with a reduction in reuse frequency and a shift in location toward the AZ periphery during high-frequency stimulation. These findings have revealed fundamental spatiotemporal properties of individual release sites in small central synapses and their activity-dependent modulation.

  15. Contagious Coronal Heating from Recurring Emergence of Magnetic Flux

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.; Falconer, David; Sterling, Alphonse; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    For each of six old bipolar active regions, we present and interpret Yohkoh/SXT and SOHO/MDI observations of the development, over several days, of enhanced coronal heating in and around the old bipole in response to new magnetic flux emerge= within the old bipole. The observations show: 1. In each active region, new flux emerges in the equatorward side of the old bipole, around a lone remaining leading sunspot and/or on the equatorward end of the neutral line of the old bipole. 2. The emerging field is marked by intense internal coronal heating, and enhanced coronal heating occurs in extended loops stemming from the emergence site. 3. In five of the six cases, a "rooster tail" of coronal loops in the poleward extent of the old bipole also brightens in response to the flux emergence. 4. There are episodes of enhanced coronal heating in surrounding magnetic fields that are contiguous with the old bipole but are not directly connected to the emerging field. From these observations, we suggest that the accommodation of localized newly emerged flux within an old active region entails far reaching adjustments in the 3D magnetic field throughout the active region and in surrounding fields in which the active region is embedded, and that these adjustments produce the extensive enhanced coronal heating. We also note that the reason for the recurrence of flux emergence in old active regions may be that active region flux tends to emerge in giant-cell convection downflows. If so, the poleward "rooster tail" is a coronal flag of a long-lasting downflow in the convection zone. This work was funded by NASA's Office of Space Science through the Solar Physics Supporting Research and Technology Program and the Sun-Earth Connection Guest Investigator Program.

  16. Summary of Tiger Team Assessment and Technical Safety Appraisal recurring concerns in the Maintenance Area

    SciTech Connect

    Not Available

    1993-01-01

    Tiger Team Assessments and Technical Safety Appraisals (TSA) were reviewed and evaluated for concerns in the Maintenance Area (MA). Two hundred and thirty one (231) maintenance concerns were identified by the Tiger Team Assessments and TSA reports. These recurring concerns appear below. A summary of the Noteworthy Practices that were identified and a compilation of the maintenance concerns for each performance objective that were not considered as recurring are also included. Where the Tiger Team Assessment and TSA identified the operating contractor or facility by name, the concern has been modified to remove the name while retaining the intent of the comment.

  17. A rare case of bilateral cystic partially differentiated nephroblastoma recurring as bilateral cystic Wilms tumour.

    PubMed

    Kurian, Jujju Jacob; Ninan, Pradeep Joseph

    2015-04-15

    Childhood cystic partially differentiated nephroblastoma (CPDN) is an uncommon renal neoplasm. Bilateral CPDN or CPDN co-existing with a cystic nephroma/Wilms tumour is extremely rare. Treatment of CPDN is by complete surgical excision. Although local recurrences are uncommon, distant metastases have not been described. We present a case of bilateral CPDN that, after complete excision, recurred as bilateral cystic Wilms tumour. To the best of our knowledge, this is the first reported case in the literature where a bilateral CPDN has recurred as bilateral Wilms tumour.

  18. Geologic context of recurring slope lineae in Melas and Coprates Chasmata, Mars

    USGS Publications Warehouse

    Chojnacki, Matthew; McEwen, Alfred; Dundas, Colin M.; Ojha, Lujendra; Urso, Anna; Sutton, Sarah

    2016-01-01

    One of the major Mars discoveries of recent years is the existence of recurring slope lineae (RSL), which suggests that liquid water occurs on or near the surface of Mars today. These dark and narrow features emerge from steep, rocky exposures and incrementally grow, fade, and reform on a seasonal basis and are detected in images from the High Resolution Imaging Science Experiment camera. RSL are known to occur at scattered midlatitude and equatorial sites with little spatial connection to one another. One major exception is the steep, low-albedo slopes of Melas and Coprates Chasmata, in Valles Marineris where RSL are detected among diverse geologic surfaces (e.g., bedrock and talus) and landforms (e.g., inselbergs and landslides). New images show topographic changes including sediment deposition on active RSL slopes. Midwall locations in Coprates and Melas appear to have more areally extensively abundant RSL and related fans as compared with other RSL sites found on Mars. Water budget estimates for regional RSL are on the order of 105 to 106 m3 of fluid, for depths of 10 to 100mm, and suggest that a significant amount of near-surface watermight be present. Many RSL are concentrated near local topographic highs, such as ridge crests or peaks, which is challenging to explain via groundwater or ice without a recharge mechanism. Collectively, results provide additional support for the notion that significant amounts of near-surface water can be found on Mars today and suggest that a widespread mechanism, possibly related to the atmosphere, is recharging RSL sources.

  19. Habituation of parasympathetic-mediated heart rate responses to recurring acoustic startle

    PubMed Central

    Chen, Kuan-Hua; Aksan, Nazan; Anderson, Steven W.; Grafft, Amanda; Chapleau, Mark W.

    2014-01-01

    Startle habituation is a type of implicit and automatic emotion regulation. Diminished startle habituation is linked to several psychiatric or neurological disorders. Most previous studies quantified startle habituation by assessing skin conductance response (SCR; reflecting sympathetic-mediated sweating), eye-blink reflex, or motor response. The habituation of parasympathetic-mediated heart rate responses to recurrent startle stimuli is not well understood. A variety of methods and metrics have been used to quantify parasympathetic activity and its effects on the heart. We hypothesized that these different measures reflect unique psychological and physiological processes that may habituate differently during repeated startle stimuli. We measured cardiac inter-beat intervals (IBIs) to recurring acoustic startle probes in 75 eight year old children. Eight acoustic stimuli of 500 ms duration were introduced at intervals of 15–25 s. Indices of parasympathetic effect included: (1) the initial rapid decrease in IBI post-startle mediated by parasympathetic inhibition (PI); (2) the subsequent IBI recovery mediated by parasympathetic reactivation (PR); (3) rapid, beat-to-beat heart rate variability (HRV) measured from the first seven IBIs following each startle probe. SCR and motor responses to startle were also measured. Results showed that habituation of PR (IBI recovery and overshoot) and SCRs were rapid and robust. In addition, changes in PR and SCR were significantly correlated. In contrast, habituation of PI (the initial decrease in IBI) was slower and relatively modest. Measurement of rapid HRV provided an index reflecting the combination of PI and PR. We conclude that different measures of parasympathetic-mediated heart rate responses to repeated startle probes habituate in a differential manner. PMID:25477830

  20. Geologic context of recurring slope lineae in Melas and Coprates Chasmata, Mars

    NASA Astrophysics Data System (ADS)

    Chojnacki, Matthew; McEwen, Alfred; Dundas, Colin; Ojha, Lujendra; Urso, Anna; Sutton, Sarah

    2016-07-01

    One of the major Mars discoveries of recent years is the existence of recurring slope lineae (RSL), which suggests that liquid water occurs on or near the surface of Mars today. These dark and narrow features emerge from steep, rocky exposures and incrementally grow, fade, and reform on a seasonal basis and are detected in images from the High Resolution Imaging Science Experiment camera. RSL are known to occur at scattered midlatitude and equatorial sites with little spatial connection to one another. One major exception is the steep, low-albedo slopes of Melas and Coprates Chasmata, in Valles Marineris where RSL are detected among diverse geologic surfaces (e.g., bedrock and talus) and landforms (e.g., inselbergs and landslides). New images show topographic changes including sediment deposition on active RSL slopes. Midwall locations in Coprates and Melas appear to have more areally extensively abundant RSL and related fans as compared with other RSL sites found on Mars. Water budget estimates for regional RSL are on the order of 105 to 106 m3 of fluid, for depths of 10 to 100 mm, and suggest that a significant amount of near-surface water might be present. Many RSL are concentrated near local topographic highs, such as ridge crests or peaks, which is challenging to explain via groundwater or ice without a recharge mechanism. Collectively, results provide additional support for the notion that significant amounts of near-surface water can be found on Mars today and suggest that a widespread mechanism, possibly related to the atmosphere, is recharging RSL sources.

  1. Spectral Study of Water Tracks as an Analog for Recurring Slope Lineae

    NASA Technical Reports Server (NTRS)

    Ojha, L.; Wilhelm, M. B.; Wray, J. J.

    2013-01-01

    Liquid water is a key requirement for life on Earth, and serves as an important constraint on present day habitability on Mars. Recurring Slope Lineae (RSL) are a unique phenomenon on Mars that may be formed by brine seeps. Their morphological, seasonal and temporal characteristics support this hypothesis; however, spectral evidence has been lacking. Ojha et al., 2013 recently analyzed CRISM images from all confirmed RSL in the southern mid-latitudes and equatorial regions and found no spectro-scopic evidence for water. Instead, enhanced abun-dances or distinct grain sizes of both ferric and ferrous minerals are observed at most sites. The strength of these spectral signatures changes as a function of sea-son, possibly indicating removal of a fine-grained sur-face component during RSL flow, precipitation of fer-ric oxides, and/or wetting of the substrate. Water tracks (WT) have been suggested as a terrestrial analog for RSL by Levy et al., 2011. WT are defined as dark surface features that extend downslope in a linear or branching fashion, usually oriented along the steepest local gradient, in the Dry Valleys of Antarctica. They can be 1-3 m in width and can have lengths up to 2 km. They share many morphological and seasonal characteristics with RSL including active growth during summer seasons and fading during winter. Snowmelt, ground ice melt and deliquescence by hygroscopic salts have been suggested as possible formation mechanisms for water tracks. No spectral work to date has been reported for water tracks.

  2. 78 FR 32608 - Safety Zones; Recurring Events in Captain of the Port Duluth Zone

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-31

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zones; Recurring Events in Captain of the Port... Safety Unit Duluth Captain of the Port (COTP) Zone. The safety zones in this proposed rule are needed to... taking place in the Duluth Captain of the Port Zone. The legal basis for the rule is the Coast...

  3. 77 FR 33970 - Safety Zones; Recurring Events in Captain of the Port New York Zone

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-08

    ... SECURITY Coast Guard 33 CFR Part 165 Safety Zones; Recurring Events in Captain of the Port New York Zone... permission of the Captain of the Port (COTP). DATES: The regulations for the safety zones described in 33 CFR... enter the regulated area. Dated: May 21, 2012. G.P. Hitchen, Captain, U.S. Coast Guard, Acting...

  4. Can a self-administered questionnaire identify workers with chronic or recurring low back pain?

    PubMed

    Takekawa, Karina Satiko; Gonçalves, Josiane Sotrate; Moriguchi, Cristiane Shinohara; Coury, Helenice Jane Cote Gil; Sato, Tatiana de Oliveira

    2015-01-01

    To verify if the Nordic Musculoskeletal Questionnaire (NMQ), Visual Analogue Scale (VAS), Roland-Morris Disability Questionnaire (RDQ) and physical examination of the lumbar spine can identify workers with chronic or recurring low back pain, using health history for reference. Fifty office workers of both sexes, aged between 19 and 55 yr, were evaluated using a standardized physical examination and the NMQ, VAS and RDQ. Discriminant analysis was performed to determine the discriminant properties of these instruments. A higher success rate (94%) was observed in the model including only the NMQ and in the model including the NMQ and the physical examination. The lowest success rate (82%) was observed in the model including the NMQ, RDQ and VAS. The NMQ was able to detect subjects with chronic or recurring low back pain with 100% sensitivity and 88% specificity. The NMQ appears to be the best instrument for identifying subjects with chronic or recurring low back pain. Thus, this self-reported questionnaire is suitable for screening workers for chronic or recurring low back pain in occupational settings.

  5. Routine and Recurring Small Transient and New Test Missions Environmental Assessment

    DTIC Science & Technology

    2008-04-01

    95th Air Base Wing Environmental Management Directorate Edwards Air Force Base, California Report Documentation Page Form... California proposes to add up to 25 aircraft, 2000 sorties per year, and 1500 military, government civilian, and contractor personnel to support small...SIGNIFICANT IMPACT (FONSI) FOR ROUTINE AND RECURRING SMALL TRANSIENT AND NEW SMALL MISSIONS ENVIRONMENTAL ASSESSMENT 1.0 INTRODUCTION The Air Force

  6. Memory Dysfunction in Caudate Infarction Caused by Heubner's Recurring Artery Occlusion

    ERIC Educational Resources Information Center

    Mizuta, Hideko; Motomura, Naoyasu

    2006-01-01

    We report five cases with caudate infarction due to Heubner's recurring artery occlusion, in which we conducted detailed memory examinations in terms of explicit memory and implicit memory. We performed the auditory verbal learning test as explicit memory tasks, and motor and cognitive procedural memory tasks, developed by Komori, as implicit…

  7. Beyond Munchausen by Proxy: A Proposed Conceptualization for Cases of Recurring, Unsubstantiated Sexual Abuse Allegations

    ERIC Educational Resources Information Center

    Lindahl, Mary W.

    2009-01-01

    In the emerging literature, cases involving recurring, unsubstantiated allegations of child sexual abuse have generally been categorized as Munchausen by proxy. Recent scholars have recommended restricting the label to the original conceptualization, involving purposeful deception motivated by psychological needs for medical attention. This leaves…

  8. 76 FR 44877 - Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-27

    .... USCG-2011-0629] RIN 1625-AA08 Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, Wrightsville Channel; Wrightsville... marine event in the Fifth Coast Guard District. The ``Wilmington YMCA Triathlon,'' conducted on...

  9. 77 FR 30929 - Special Local Regulations for Marine Events, Temporary Change of Dates for Recurring Marine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-24

    ... Number USCG-2012-0341] RIN 1625-AA08 Special Local Regulations for Marine Events, Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, Wrightsville Channel; Wrightsville... marine event in the Fifth Coast Guard District, specifically the ``Wilmington YMCA Triathlon'',...

  10. 77 FR 15320 - Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-15

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, Bogue Sound; Morehead City... event in the Fifth Coast Guard District. This change applies only to the ``Crystal Coast Super...

  11. 76 FR 57645 - Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-16

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulations for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, Wrightsville Channel... following correction is made: Sec. 100.501 Special Local Regulations; Marine Events in the Fifth Coast...

  12. 78 FR 38829 - Special Local Regulations; Recurring Marine Events in the Seventh Coast Guard District

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-28

    ... SECURITY Coast Guard 33 CFR Part 100 Special Local Regulations; Recurring Marine Events in the Seventh Coast Guard District AGENCY: Coast Guard, DHS. ACTION: Notice of enforcement of regulation. SUMMARY: The Coast Guard will enforce the special local regulation for the St. John 4th of July Carnival...

  13. 78 FR 32219 - Safety Zone, Temporary Change for Recurring Fifth Coast Guard District Fireworks Displays, Middle...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-29

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone, Temporary Change for Recurring Fifth Coast Guard District Fireworks Displays, Middle River; Baltimore County, MD AGENCY: Coast Guard, DHS. ACTION: Notice of Proposed Rulemaking. SUMMARY: The Coast Guard is proposing a temporary change to...

  14. 76 FR 69634 - Safety Zone; Temporary Change for Recurring Fireworks Display Within the Fifth Coast Guard...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-09

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Temporary Change for Recurring Fireworks Display Within the Fifth Coast Guard District, Wrightsville Beach, NC AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is temporarily changing the enforcement period and...

  15. 78 FR 34886 - Special Local Regulations; Recurring Marine Events in the Seventh Coast Guard District

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-11

    ... SECURITY Coast Guard 33 CFR Part 100 Special Local Regulations; Recurring Marine Events in the Seventh Coast Guard District AGENCY: Coast Guard, DHS. ACTION: Notice of enforcement of regulation. SUMMARY: The Coast Guard will enforce the regulation pertaining to the Beaufort Water Festival from 1 p.m. through...

  16. 78 FR 35756 - Special Local Regulations; Recurring Marine Events in the Seventh Coast Guard District

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-14

    ... SECURITY Coast Guard 33 CFR Part 100 Special Local Regulations; Recurring Marine Events in the Seventh Coast Guard District AGENCY: Coast Guard, DHS. ACTION: Notice of enforcement of regulations. SUMMARY: The Coast Guard will enforce the Fourth of July Fireworks Display regulations on certain...

  17. 78 FR 67026 - Special Local Regulations; Recurring Marine Events in the Seventh Coast Guard District

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-08

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulations; Recurring Marine Events in the Seventh Coast Guard District AGENCY: Coast Guard, DHS. ACTION: Notice of enforcement of regulation. SUMMARY: The Coast Guard will enforce the special local regulations pertaining to the Key West...

  18. The Character of Curriculum Studies: Bildung, Currere, and the Recurring Question of the Subject

    ERIC Educational Resources Information Center

    Pinar, William F.

    2011-01-01

    This volume assembles essays addressing the recurring question of the "subject," understood both as human person and school subject, thereby elaborating the subjective and disciplinary character of curriculum studies. After examining scholarship on the "subject," Pinar critiques its absence in the new sociology of curriculum,…

  19. [A forensic medicine perspective on recurring episodes of intimate partner violence].

    PubMed

    Seifert, Dragana; Heinemann, Axel; Anders, Sven; Schröer, Judith; Sperhake, Jan; Glet, Alke; Püschel, Klaus

    2007-01-01

    During a three year period, 418 victims of intimate partner violence (IPV) were examined and their injuries documented at the Center for Victims of Violence (CVV) in Hamburg, Germany. All victims were questioned if their acute injuries were attributable to recurring acts of violence by the same intimate partner. The victims' experiences with recurring IPV were analyzed and associated risk factors as well as findings of acute physical injuries were integrated into the assesment. Overall, women were significantly more often victims of recurring episodes of IPV than men. In 35.4% of cases, victims of recurring IPV sustained injuries to three or more body regions. However, women who were victimized during a single act of violence, presented with the same distribution of injuries in only 21.1% of cases (p = 0.01). The results emphasize the fact that IPV often manifests itself in a spiraling escalation of physical violence. Furthermore, blunt force trauma to the head was diagnosed significantly more often (p = 0.05). The risk of sustaining a head injury was equally high for women who experienced a first-time violent episode by their ex-partner as it was for married women or women living in a non-marital partnership during recurring episodes of IPV. In an effort to reduce the increased risk for victims of IPV, health care personnel are highly encouraged to partake in forensic medicine based continuing education. This preventative measure may prepare clinicians to recognize IPV earlier as well as to treat and advise clients appropriately.

  20. 75 FR 33502 - Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-14

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District AGENCY: Coast Guard, DHS... special local regulations for a recurring marine event in the Fifth Coast Guard District....

  1. 75 FR 17103 - Special Local Regulation for Marine Event; Temporary Change of Dates for Recurring Marine Event...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-05

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Event; Temporary Change of Dates for Recurring Marine Event in the Fifth Coast Guard District AGENCY: Coast Guard, DHS... enforcement period of special local regulations for recurring marine event in the Fifth Coast Guard...

  2. 76 FR 1564 - Special Local Regulation for Marine Event; Temporary Change of Dates for Recurring Marine Event...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-11

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Event; Temporary Change of Dates for Recurring Marine Event in the Fifth Coast Guard District AGENCY: Coast Guard, DHS... enforcement periods of special local regulations for recurring marine events in the Fifth Coast Guard...

  3. 77 FR 14959 - Special Local Regulation for Marine Event; Temporary Change of Dates for Recurring Marine Events...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-14

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Event; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District AGENCY: Coast Guard, DHS... changing the enforcement periods of special local regulations for recurring marine events in the...

  4. 75 FR 29886 - Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-28

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District AGENCY: Coast Guard, DHS... special local regulations for recurring marine events in the Fifth Coast Guard District. These...

  5. 76 FR 55558 - Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-08

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, John H. Kerr Reservoir... temporarily change the enforcement period of special local regulations for one recurring marine event in...

  6. 76 FR 13884 - Special Local Regulation for Marine Event; Temporary Change of Dates for Recurring Marine Event...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-15

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Event; Temporary Change of Dates for Recurring Marine Event in the Fifth Coast Guard District AGENCY: Coast Guard, DHS... special local regulations for a recurring marine event in the Fifth Coast Guard District....

  7. 75 FR 17099 - Special Local Regulation for Marine Event; Temporary Change of Dates for Recurring Marine Event...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-05

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Event; Temporary Change of Dates for Recurring Marine Event in Fifth Coast Guard District AGENCY: Coast Guard, DHS. ACTION... period of special local regulations for recurring marine events in Fifth Coast Guard District....

  8. 76 FR 36308 - Special Local Regulation for Marine Events; Temporary Change of dates for Recurring Marine Events...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-22

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Events; Temporary Change of dates for Recurring Marine Events in the Fifth Coast Guard District; Mill Creek, Hampton, VA... the enforcement period of one special local regulation for recurring marine events in the Fifth...

  9. 75 FR 20294 - Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-19

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District AGENCY: Coast Guard, DHS... period of special local regulations for recurring marine events in the Fifth Coast Guard District....

  10. 75 FR 748 - Special Local Regulation for Marine Events; Recurring Marine Events in the Fifth Coast Guard...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-06

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Events; Recurring Marine Events in the Fifth Coast Guard District AGENCY: Coast Guard, DHS. ACTION: Final rule. SUMMARY: The Coast Guard is amending the list of recurring marine events within the Fifth Coast Guard...

  11. 33 CFR 100.130 - Special Local Regulations; Recurring Annual Marine Events in Sector Boston Captain of the Port Zone.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...; Recurring Annual Marine Events in Sector Boston Captain of the Port Zone. 100.130 Section 100.130 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY REGATTAS AND MARINE PARADES SAFETY OF LIFE ON NAVIGABLE WATERS § 100.130 Special Local Regulations; Recurring Annual Marine Events...

  12. 77 FR 25070 - Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-27

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, Ocean City Maryland... recurring marine event in the Fifth Coast Guard District, specifically, the ``Ocean City Maryland...

  13. Auditory Perception of Spatiotemporal Patterns

    ERIC Educational Resources Information Center

    Tolkmitt, Frank J.; Brindley, Robin

    1977-01-01

    To test the tendency of subjects to perceptually organize discrete temporal patterns with regard to runs of identical stimulus events, spatiotemporal patterns of white noise were presented for reproduction. It is suggested that changes in runs of auditory patterns are perceptually analogous to changes in contours of visual patterns. (Editor/RK)

  14. Mesoscale Modeling of Water Vapor and Dust in Valles Marineris: Atmospheric Influences on Recurring Slope Lineae.

    NASA Astrophysics Data System (ADS)

    Leung, C. W. S.; Rafkin, S. C.; McEwen, A. S.

    2015-12-01

    Extensive recurring slope lineae (RSL) activity has been detected in Valles Marineris on Mars and coincides with regions where water ice fogs appear [1]. The origin of the water driving RSL flow is not well understood, but observational evidence suggests atmospheric processes play a crucial role [2]. Provided the atmospheric vapor concentration is high enough, water ice fogs can form overnight if the surface temperature cools below the condensation temperature. Correlations between dust storms and flow rates suggest that atmospheric dust opacity, and its influence on air temperature, also has a significant effect on RSL activity. We investigate planetary boundary layer processes that govern the hydrological cycle and dust cycle on Mars using a mesoscale atmospheric model to simulate the distribution of water and dust with respect to regional atmospheric circulations. Our simulations in Valles Marineris show a curious temperature structure, where the inside of the canyon appears warmer relative to the plateaus immediately outside. For a well-mixed atmosphere, this temperature structure indicates that when the atmosphere inside the canyon is saturated and fog is present within Valles Marineris, fog and low-lying clouds should also be present on the cooler surrounding plateaus as well. However, images taken with the Mars Express High Resolution Stereo Camera (HRSC) show instances where water ice fog appeared exclusively inside the canyon. These results have important implications for the origin and concentration of water vapor in Valles Marineris, with possible connections to RSL. The potential temperatures from our simulations show a high level of stability inside the canyon produced dynamically by sinking air. However, afternoon updrafts along the canyon walls indicate that over time, water vapor within the chasm would escape along the sides of the canyon. Again, this suggests a local source or mechanism to concentrate water vapor is needed to explain the fog

  15. Recurring exon deletions in the haptoglobin (HP) gene associate with lower blood cholesterol levels

    PubMed Central

    Boettger, Linda M.; Salem, Rany M.; Handsaker, Robert E.; Peloso, Gina; Kathiresan, Sekar; Hirschhorn, Joel; McCarroll, Steven A.

    2016-01-01

    Two exons of the human haptoglobin (HP) gene exhibit copy number variation that affects HP multimerization and underlies one of the first protein polymorphisms identified in humans. The evolutionary origins and medical significance of this polymorphism have been uncertain. Here we show that this variation has likely arisen from the recurring reversion of an ancient hominin-specific duplication of these exons. Though this polymorphism has been largely invisible to genome-wide genetic studies to date, we describe a way to analyze it by imputation from SNP haplotypes and find among 22,288 individuals that these HP exonic deletions associate with reduced LDL and total cholesterol levels. We show that these deletions, and a SNP that affects HP expression, are the likely drivers of the strong but complex association of cholesterol levels to SNPs near HP. Recurring exonic deletions in the haptoglobin gene likely enhance human health by lowering cholesterol levels in the blood. PMID:26901066

  16. [Repetitive phenomenona in the spontaneous speech of aphasic patients: perseveration, stereotypy, echolalia, automatism and recurring utterance].

    PubMed

    Wallesch, C W; Brunner, R J; Seemüller, E

    1983-12-01

    Repetitive phenomena in spontaneous speech were investigated in 30 patients with chronic infarctions of the left hemisphere which included Broca's and/or Wernicke's area and/or the basal ganglia. Perseverations, stereotypies, and echolalias occurred with all types of brain lesions, automatisms and recurring utterances only with those patients, whose infarctions involved Wernicke's area and basal ganglia. These patients also showed more echolalic responses. The results are discussed in view of the role of the basal ganglia as motor program generators.

  17. Tracked Vehicle Dynamics Modeling and Simulation Methodology, with Control, using RecurDyn Software Package

    DTIC Science & Technology

    2011-09-01

    track segment, with pins connecting each track segment. The modeler must align each segment properly with the track pins with the sprocket teeth and...representative track segment is copied and linked together using a simplified algorithm which assumes each track segment is identical, with force/ torque pairs...simulation, RecurDyn feeds CoLink the desired inputs (error term, speed, direction, etc), CoLink performs the programmed operation (generates torque

  18. Spatio-temporal evaluation matrices for geospatial data

    NASA Astrophysics Data System (ADS)

    Triglav, Joc; Petrovič, Dušan; Stopar, Bojan

    2011-02-01

    The global geospatial community is investing substantial effort in providing tools for geospatial data-quality information analysis and systematizing the criteria for geospatial data quality. The importance of these activities is increasing, especially in the last decade, which has witnessed an enormous expansion of geospatial data use in general and especially among mass users. Although geospatial data producers are striving to define and present data-quality standards to users and users increasingly need to assess the fitness for use of the data, the success of these activities is still far from what is expected or required. As a consequence, neglect or misunderstanding of data quality among users results in misuse or risks. This paper presents an aid in spatio-temporal quality evaluation through the use of spatio-temporal evaluation matrices (STEM) and the index of spatio-temporal anticipations (INSTANT) matrices. With the help of these two simple tools, geospatial data producers can systematically categorize and visualize the granularity of their spatio-temporal data, and users can present their requirements in the same way using business intelligence principles and a Web 2.0 approach. The basic principles and some examples are presented in the paper, and potential further applied research activities are briefly described.

  19. Bit error rate tester using fast parallel generation of linear recurring sequences

    DOEpatents

    Pierson, Lyndon G.; Witzke, Edward L.; Maestas, Joseph H.

    2003-05-06

    A fast method for generating linear recurring sequences by parallel linear recurring sequence generators (LRSGs) with a feedback circuit optimized to balance minimum propagation delay against maximal sequence period. Parallel generation of linear recurring sequences requires decimating the sequence (creating small contiguous sections of the sequence in each LRSG). A companion matrix form is selected depending on whether the LFSR is right-shifting or left-shifting. The companion matrix is completed by selecting a primitive irreducible polynomial with 1's most closely grouped in a corner of the companion matrix. A decimation matrix is created by raising the companion matrix to the (n*k).sup.th power, where k is the number of parallel LRSGs and n is the number of bits to be generated at a time by each LRSG. Companion matrices with 1's closely grouped in a corner will yield sparse decimation matrices. A feedback circuit comprised of XOR logic gates implements the decimation matrix in hardware. Sparse decimation matrices can be implemented with minimum number of XOR gates, and therefore a minimum propagation delay through the feedback circuit. The LRSG of the invention is particularly well suited to use as a bit error rate tester on high speed communication lines because it permits the receiver to synchronize to the transmitted pattern within 2n bits.

  20. Spatiotemporal dynamics of HIV infection

    NASA Astrophysics Data System (ADS)

    Strain, Matthew Carl

    Mathematical models of the dynamics of infection with the human immunodeficiency virus (HIV) have contributed to tremendous advances over the past 20 years. This thesis extends this previous work by exploring the importance of spatial heterogeneity in HIV infection both in vitro and in vivo in patients treated with highly-active antiretroviral therapy. Viral infections propagate locally in space, yet HIV infection has been widely regarded as equilibrated over the entire body of an infected patient. This dissertation constructs and explores a cellular automata model of viral spread at the cellular level. Coupling the automata to a blood compartment represented by a differential equation leads to a whole-body model of HIV infection that explicitly includes spatial effects at both the cellular and tissue levels. These models are tested by comparison with experimental data. A central prediction of the spatial model is that, due to competition between Brownian motion and viral lability, HIV infectivity increases with target cell density. This production is verified in a series of in vitro experiments in cell culture. The predicted independence of inhibitory concentrations of antiretoviral agents is verified for nevirapine, but azidothymidine inhibits HIV replication less efficiently in more dense cultures. These in vitro results suggest that systems allowing cell concentrations closer to tissue densities would better reflect virus replication kinetics, although standard measures of relative drug susceptibility may accurately reflect in vivo conditions. The coupled spatial model of in vivo dynamics is compared with novel mathematical analysis of experiments in HIV-infected patients. These analyses indicate that HIV DNA provides a useful marker of the size of long-lived cellular reservoirs of HIV. Levels of HIV DNA in peripheral blood are predictive of the average rate of residual virus production after years of treatment, regardless of whether patients initiate therapy

  1. Spatiotemporal Interpolation for Environmental Modelling

    PubMed Central

    Susanto, Ferry; de Souza, Paulo; He, Jing

    2016-01-01

    A variation of the reduction-based approach to spatiotemporal interpolation (STI), in which time is treated independently from the spatial dimensions, is proposed in this paper. We reviewed and compared three widely-used spatial interpolation techniques: ordinary kriging, inverse distance weighting and the triangular irregular network. We also proposed a new distribution-based distance weighting (DDW) spatial interpolation method. In this study, we utilised one year of Tasmania’s South Esk Hydrology model developed by CSIRO. Root mean squared error statistical methods were performed for performance evaluations. Our results show that the proposed reduction approach is superior to the extension approach to STI. However, the proposed DDW provides little benefit compared to the conventional inverse distance weighting (IDW) method. We suggest that the improved IDW technique, with the reduction approach used for the temporal dimension, is the optimal combination for large-scale spatiotemporal interpolation within environmental modelling applications. PMID:27509497

  2. Nonlinear Synchronization Analysis of Spatiotemporal Heart Data

    NASA Astrophysics Data System (ADS)

    Simonotto, Jennifer D.; Furman, Michael D.; Spano, Mark L.; Ditto, William L.; Liu, Gang; Kavanagh, Katherine M.

    2003-08-01

    A high-speed video camera and voltage-sensitive dyes were used to acquire high resolution (80×80 pixels) and high-speed (500 μs/frame) optical signals of ventricular fibrillation in a Langendorff-perfused porcine heart. The resulting spatiotemporal dynamics were recorded before and after the application of a defibrillation shock in order to study the mechanism of defibrillation failure. We calculate nonlinear synchronization index measures to qualify the evolution of different types of activity on the heart surface (focal, reentry). We observe changes with time in the spatial distribution of the first Fourier mode, showing that two main types of activity compete on the heart surface during a failed defibrillation.

  3. Boron Neutron Capture Therapy in the Treatment of Locally Recurred Head and Neck Cancer

    SciTech Connect

    Kankaanranta, Leena; Seppaelae, Tiina; Koivunoro, Hanna; Saarilahti, Kauko; Atula, Timo; Collan, Juhani; Salli, Eero; Kortesniemi, Mika; Uusi-Simola, Jouni; Maekitie, Antti; Seppaenen, Marko; Minn, Heikki; Kotiluoto, Petri; Auterinen, Iiro; Savolainen, Sauli; Kouri, Mauri; Joensuu, Heikki

    2007-10-01

    Purpose: Head and neck carcinomas that recur locally after conventional irradiation pose a difficult therapeutic problem. We evaluated safety and efficacy of boron neutron capture therapy (BNCT) in the treatment of such cancers. Methods and Materials: Twelve patients with inoperable, recurred, locally advanced (rT3, rT4, or rN2) head and neck cancer were treated with BNCT in a prospective, single-center Phase I-II study. Prior treatments consisted of surgery and conventionally fractionated photon irradiation to a cumulative dose of 56-74 Gy administered with or without concomitant chemotherapy. Tumor responses were assessed using the RECIST (Response Evaluation Criteria in Solid Tumors) criteria and adverse effects using the National Cancer Institute common toxicity grading v3.0. Intravenously administered boronophenylalanine-fructose (BPA-F, 400 mg/kg) was used as the boron carrier. Each patient was scheduled to be treated twice with BNCT. Results: Ten patients received BNCT twice; 2 were treated once. Ten (83%) patients responded to BNCT, and 2 (17%) had tumor growth stabilization for 5.5 and 7.6 months. The median duration of response was 12.1 months; six responses were ongoing at the time of analysis or death (range, 4.9-19.2 months). Four (33%) patients were alive without recurrence with a median follow-up of 14.0 months (range, 12.8-19.2 months). The most common acute adverse effects were mucositis, fatigue, and local pain; 2 patients had a severe (Grade 3) late adverse effect (xerostomia, 1; dysphagia, 1). Conclusions: Boron neutron capture therapy is effective and safe in the treatment of inoperable, locally advanced head and neck carcinomas that recur at previously irradiated sites.

  4. Recurring issues in the IEA, the discipline and the profession of ergonomics/human factors.

    PubMed

    Wilson, John R

    2012-01-01

    Although the past 25 years have seen many apparently new challenges for the academic discipline and the professional practice of ergonomics/human factors, and for the International Ergonomics Association, many issues in fact have recurred over the period. This paper takes the relevant decades and de3scribes the internal and external priorities of the IEA at the time, the main developments for researchers and practitioners, and the author's own professional interests at the time..Such an admittedly partial description of events and priorities could feed into current attempts to strengthen the position of ergonomics/ human factors for this and subsequent decades.

  5. Noise tolerant spatiotemporal chaos computing

    SciTech Connect

    Kia, Behnam; Kia, Sarvenaz; Ditto, William L.; Lindner, John F.; Sinha, Sudeshna

    2014-12-01

    We introduce and design a noise tolerant chaos computing system based on a coupled map lattice (CML) and the noise reduction capabilities inherent in coupled dynamical systems. The resulting spatiotemporal chaos computing system is more robust to noise than a single map chaos computing system. In this CML based approach to computing, under the coupled dynamics, the local noise from different nodes of the lattice diffuses across the lattice, and it attenuates each other's effects, resulting in a system with less noise content and a more robust chaos computing architecture.

  6. Enhancing chaoticity of spatiotemporal chaos.

    PubMed

    Li, Xiaowen; Zhang, Heqiao; Xue, Yu; Hu, Gang

    2005-01-01

    In some practical situations strong chaos is needed. This introduces the task of chaos control with enhancing chaoticity rather than suppressing chaoticity. In this paper a simple method of linear amplifications incorporating modulo operations is suggested to make spatiotemporal systems, which may be originally chaotic or nonchaotic, strongly chaotic. Specifically, this control can eliminate periodic windows, increase the values and the number of positive Lyapunov exponents, make the probability distributions of the output chaotic sequences more homogeneous, and reduce the correlations of chaotic outputs for different times and different space units. The applicability of the method to practical tasks, in particular to random number generators and secure communications, is briefly discussed.

  7. Noise tolerant spatiotemporal chaos computing.

    PubMed

    Kia, Behnam; Kia, Sarvenaz; Lindner, John F; Sinha, Sudeshna; Ditto, William L

    2014-12-01

    We introduce and design a noise tolerant chaos computing system based on a coupled map lattice (CML) and the noise reduction capabilities inherent in coupled dynamical systems. The resulting spatiotemporal chaos computing system is more robust to noise than a single map chaos computing system. In this CML based approach to computing, under the coupled dynamics, the local noise from different nodes of the lattice diffuses across the lattice, and it attenuates each other's effects, resulting in a system with less noise content and a more robust chaos computing architecture.

  8. Spatiotemporal chaos involving wave instability

    NASA Astrophysics Data System (ADS)

    Berenstein, Igal; Carballido-Landeira, Jorge

    2017-01-01

    In this paper, we investigate pattern formation in a model of a reaction confined in a microemulsion, in a regime where both Turing and wave instability occur. In one-dimensional systems, the pattern corresponds to spatiotemporal intermittency where the behavior of the systems alternates in both time and space between stationary Turing patterns and traveling waves. In two-dimensional systems, the behavior initially may correspond to Turing patterns, which then turn into wave patterns. The resulting pattern also corresponds to a chaotic state, where the system alternates in both space and time between standing wave patterns and traveling waves, and the local dynamics may show vanishing amplitude of the variables.

  9. Spatiotemporal Stochastic Resonance:Theory and Experiment

    NASA Astrophysics Data System (ADS)

    Peter, Jung

    1996-03-01

    The amplification of weak periodic signals in bistable or excitable systems via stochastic resonance has been studied intensively over the last years. We are going one step further and ask: Can noise enhance spatiotemporal patterns in excitable media and can this effect be observed in nature? To this end, we are looking at large, two dimensional arrays of coupled excitable elements. Due to the coupling, excitation can propagate through the array in form of nonlinear waves. We observe target waves, rotating spiral waves and other wave forms. If the coupling between the elements is below a critical threshold, any excitational pattern will die out in the absence of noise. Below this threshold, large scale rotating spiral waves - as they are observed above threshold - can be maintained by a proper level of the noise[1]. Furthermore, their geometric features, such as the curvature can be controlled by the homogeneous noise level[2]. If the noise level is too large, break up of spiral waves and collisions with spontaneously nucleated waves yields spiral turbulence. Driving our array with a spatiotemporal pattern, e.g. a rotating spiral wave, we show that for weak coupling the excitational response of the array shows stochastic resonance - an effect we have termed spatiotemporal stochastic resonance. In the last part of the talk I'll make contact with calcium waves, observed in astrocyte cultures and hippocampus slices[3]. A. Cornell-Bell and collaborators[3] have pointed out the role of calcium waves for long-range glial signaling. We demonstrate the similarity of calcium waves with nonlinear waves in noisy excitable media. The noise level in the tissue is characterized by spontaneous activity and can be controlled by applying neuro-transmitter substances[3]. Noise effects in our model are compared with the effect of neuro-transmitters on calcium waves. [1]P. Jung and G. Mayer-Kress, CHAOS 5, 458 (1995). [2]P. Jung and G. Mayer-Kress, Phys. Rev. Lett.62, 2682 (1995). [3

  10. Spatio-temporal evolution of rockfall activity from 2007 to 2011 at the Piton de la Fournaise volcano inferred from seismic data

    NASA Astrophysics Data System (ADS)

    Hibert, Clément; Mangeney, Anne; Grandjean, Gilles; Peltier, Aline; DiMuro, Andrea; Shapiro, Nikolai M.; Ferrazzini, Valérie; Boissier, Patrice; Durand, Virginie; Kowalski, Philippe

    2017-03-01

    Seismic data have been used to catalog the location and volume of most of the rockfalls that occurred at the Piton de la Fournaise volcano from May 2007, just after the major collapse of the Dolomieu summit crater floor, to May 2011. This catalog made it possible to compare the evolution of the number and volume of rockfalls at a high temporal resolution and to investigate their links with eruptions, seismicity, deformations and rainfalls affecting the Piton de la Fournaise volcano. Results show that the purge of unstable areas created by the Dolomieu crater floor collapse occurred in two phases: a first phase, lasting three months, during which the intense rockfall activity immediately following the collapse decreased abruptly and a second phase, lasting more than two years, during which the daily volume of the rockfalls slowly decreased before reaching a steady state. A detailed study of 4 time periods, including 3 eruptive cycles, indicates that strong seismicity can increase the number of rockfalls. Furthermore, when a dike reaches the surface at the summit of the central cone, giving birth to an eruption, the associated local forcing can in some cases increase the volume of rockfalls, possibly by creating or expanding weak zones. In most cases, this is not observed for dike intrusions that do not reach the surface. The newly created weak zones are most often far from the eruptive fissures of the ongoing eruption, but close to the location of the next eruption. This suggests that these distant zones are also weakened at depth, thus creating preferred paths for future dikes propagating toward the surface. The impact of rainfall on rockfall activity was also studied, given that La Réunion Island is subject to very intense rainfall events. Our results show that rainfall can in some cases trigger rockfalls rapidly, with response times of less than a day, but not systematically, and no triggering rainfall threshold was found.

  11. Recurring features of extreme rainfall events close to Veneto coast during autumn

    NASA Astrophysics Data System (ADS)

    Monai, M.; Barbi, A.; Racca, R.

    2010-09-01

    warm air coming from Adriatic sea, that is still warm (sea surface temperature above 20°C) in September; - previous weather conditions (7-10 days) with anticyclonic situation (frequently a ridge from north-Africa) with temperatures higher than usual. During most intense phases, recurring features were evidenced: - convective rains with significant thunderstorm activity; such systems are often associated to regeneration of cells, in the same coastal area; - convergence lines at low levels associated with winds coming from SE (from the sea) on the coast, and from NE (from the plane) immediately inland. It is particularly important to underline that rainfall values on short periods were extremely high if compared with mean annual amount: during last four episodes , rainfall amounts between 130 and 320 mm were recorded in 12 hours, i.e. during half a day something like 1/8 and 1/3 of total mean annual amount has fallen. Remarkable also intensity of rainfall : values like 90 mm in half an hour, or 125 mm in 1 hour were recorded. The final goal of this study was to better understand meteorological conditions associated with such events to improve forecasting and nowcasting skill. This is a crucial benefit for a Regional Met Service that must alert and support civil defence system properly, as is the case for Meteorological Centre of ARPAV in Veneto. Furthermore it is important to underline the fact that coastal area of Veneto is densely populated and it is one of the most important areas of Italian tourism, including the city of Venice and several seaside resorts with more than twenty millions of presences per year.

  12. Spatiotemporal Thinking in the Geosciences

    NASA Astrophysics Data System (ADS)

    Shipley, T. F.; Manduca, C. A.; Ormand, C. J.; Tikoff, B.

    2011-12-01

    Reasoning about spatial relations is a critical skill for geoscientists. Within the geosciences different disciplines may reason about different sorts of relationships. These relationships may span vastly different spatial and temporal scales (from the spatial alignment in atoms in crystals to the changes in the shape of plates). As part of work in a research center on spatial thinking in STEM education, we have been working to classify the spatial skills required in geology, develop tests for each spatial skill, and develop the cognitive science tools to promote the critical spatial reasoning skills. Research in psychology, neurology and linguistics supports a broad classification of spatial skills along two dimensions: one versus many objects (which roughly translates to object- focused and navigation focused skills) and static versus dynamic spatial relations. The talk will focus on the interaction of space and time in spatial cognition in the geosciences. We are working to develop measures of skill in visualizing spatiotemporal changes. A new test developed to measure visualization of brittle deformations will be presented. This is a skill that has not been clearly recognized in the cognitive science research domain and thus illustrates the value of interdisciplinary work that combines geosciences with cognitive sciences. Teaching spatiotemporal concepts can be challenging. Recent theoretical work suggests analogical reasoning can be a powerful tool to aid student learning to reason about temporal relations using spatial skills. Recent work in our lab has found that progressive alignment of spatial and temporal scales promotes accurate reasoning about temporal relations at geological time scales.

  13. Spatio-temporal patterns in simple models of marine systems

    NASA Astrophysics Data System (ADS)

    Feudel, U.; Baurmann, M.; Gross, T.

    2009-04-01

    Spatio-temporal patterns in marine systems are a result of the interaction of population dynamics with physical transport processes. These physical transport processes can be either diffusion processes in marine sediments or in the water column. We study the dynamics of one population of bacteria and its nutrient in in a simplified model of a marine sediments, taking into account that the considered bacteria possess an active as well as an inactive state, where activation is processed by signal molecules. Furthermore the nutrients are transported actively by bioirrigation and passively by diffusion. It is shown that under certain conditions Turing patterns can occur which yield heterogeneous spatial patterns of the species. The influence of bioirrigation on Turing patterns leads to the emergence of ''hot spots``, i.e. localized regions of enhanced bacterial activity. All obtained patterns fit quite well to observed patterns in laboratory experiments. Spatio-temporal patterns appear in a predator-prey model, used to describe plankton dynamics. These patterns appear due to the simultaneous emergence of Turing patterns and oscillations in the species abundance in the neighborhood of a Turing-Hopf bifurcation. We observe a large variety of different patterns where i) stationary heterogeneous patterns (e.g. hot and cold spots) compete with spatio-temporal patterns ii) slowly moving patterns are embedded in an oscillatory background iii) moving fronts and spiral waves appear.

  14. The Voxel-Wise Functional Connectome Can Be Efficiently Derived from Co-activations in a Sparse Spatio-Temporal Point-Process

    PubMed Central

    Tagliazucchi, Enzo; Siniatchkin, Michael; Laufs, Helmut; Chialvo, Dante R.

    2016-01-01

    consist of all-or-none temporally localized events, analogous to the avalanches of neural activity observed in recordings of local field potentials (LFP), an observation of potentially high neurobiological relevance. PMID:27601975

  15. Spatiotemporal localization and categorization of human actions in unsegmented image sequences.

    PubMed

    Oikonomopoulos, Antonios; Patras, Ioannis; Pantic, Maja

    2011-04-01

    In this paper we address the problem of localization and recognition of human activities in unsegmented image sequences. The main contribution of the proposed method is the use of an implicit representation of the spatiotemporal shape of the activity which relies on the spatiotemporal localization of characteristic ensembles of feature descriptors. Evidence for the spatiotemporal localization of the activity is accumulated in a probabilistic spatiotemporal voting scheme. The local nature of the proposed voting framework allows us to deal with multiple activities taking place in the same scene, as well as with activities in the presence of clutter and occlusion. We use boosting in order to select characteristic ensembles per class. This leads to a set of class specific codebooks where each codeword is an ensemble of features. During training, we store the spatial positions of the codeword ensembles with respect to a set of reference points, as well as their temporal positions with respect to the start and end of the action instance. During testing, each activated codeword ensemble casts votes concerning the spatiotemporal position and extend of the action, using the information that was stored during training. Mean Shift mode estimation in the voting space provides the most probable hypotheses concerning the localization of the subjects at each frame, as well as the extend of the activities depicted in the image sequences. We present classification and localization results for a number of publicly available datasets, and for a number of sequences where there is a significant amount of clutter and occlusion.

  16. Multisensory control of hippocampal spatiotemporal selectivity.

    PubMed

    Ravassard, Pascal; Kees, Ashley; Willers, Bernard; Ho, David; Aharoni, Daniel; Cushman, Jesse; Aghajan, Zahra M; Mehta, Mayank R

    2013-06-14

    The hippocampal cognitive map is thought to be driven by distal visual cues and self-motion cues. However, other sensory cues also influence place cells. Hence, we measured rat hippocampal activity in virtual reality (VR), where only distal visual and nonvestibular self-motion cues provided spatial information, and in the real world (RW). In VR, place cells showed robust spatial selectivity; however, only 20% were track active, compared with 45% in the RW. This indicates that distal visual and nonvestibular self-motion cues are sufficient to provide selectivity, but vestibular and other sensory cues present in RW are necessary to fully activate the place-cell population. In addition, bidirectional cells preferentially encoded distance along the track in VR, while encoding absolute position in RW. Taken together, these results suggest the differential contributions of these sensory cues in shaping the hippocampal population code. Theta frequency was reduced, and its speed dependence was abolished in VR, but phase precession was unaffected, constraining mechanisms governing both hippocampal theta oscillations and temporal coding. These results reveal cooperative and competitive interactions between sensory cues for control over hippocampal spatiotemporal selectivity and theta rhythm.

  17. Recurring two-stage evolutionary programming: a novel approach for numeric optimization.

    PubMed

    Alam, Mohammad Shafiul; Islam, Md Monirul; Yao, Xin; Murase, Kazuyuki

    2011-10-01

    In the application of evolutionary algorithms (EAs) to complex problem solving, it is essential to maintain proper balance between global exploration and local exploitation to achieve a good near-optimum solution to the problem. This paper presents a recurring two-stage evolutionary programming (RTEP) to balance the explorative and exploitative features of the conventional EAs. Unlike most previous works, RTEP is based on repeated and alternated execution of two different stages, namely, the exploration and exploitation stages, each with its own mutation operator, selection strategy, and explorative/exploitative objective. Both analytical and empirical studies have been carried out to understand the necessity of repeated and alternated exploration and exploitation operations in EAs. A suite of 48 benchmark numerical optimization problems has been used in the empirical studies. The experimental results show the remarkable effectiveness of the repeated exploration and exploitation operations employed by RTEP.

  18. Overview of historical recurring low-amplitude floods in Lower Provence, Southeastern France (1700-1950)

    NASA Astrophysics Data System (ADS)

    Maughan, Nicolas

    2015-04-01

    In the Mediterranean world, water plays a prominent role as a « prime mover » in the development of urban and rural spaces. But, the specificities of the typical climate require a management of a natural resource that varies permanently between scarcity and abundance. Since Antiquity, the chronic lack of freshwater could be limited thanks to large hydraulic infrastructures while the flood risk management has always been a recurring problem for rural and urban communities. Because of brief, intense and irregularly distributed rain, amplified by a mountainous topography, stream floods often are heavy and flash with catastrophic consequences. However, often only past extremefloods were studied because both their consequences and available archival materials they have left while many recurring low-amplitude floodshave resulted in severe damagesto hydraulic and road infrastructures, in loss of agricultural soils and inconflicts between citizens and administration. Indeed, these ones were a central problem for rural and urban settlements and for the managementof water bodies.It seems interesting to present adetailed overview of historical recurring low-amplitude floods and consider how local societies have chosen to manage these questions and how these small hydrological events have contributed to shape existing current hydrological and geomorphologicalstructure of hydrosystems. In this context, the Lower Provence area (especially the Bouches-du-Rhône district, southeastern France), subject to recurring floods for centuries, appears to be a perfect place to explore and understand these questions. The decision to start the study at the dawn of the Eighteenth Century is especially interesting because it's a turning point for economic, scientific and engineering development in many European countries during whichdisasters and environmental health risks, including flooding, begin to become a real social and technical problem for authorities and citizens. Moreover, from

  19. Chinese green tea and acute hepatitis: a rare yet recurring theme.

    PubMed

    Lugg, Sebastian Thomas; Braganza Menezes, Darryl; Gompertz, Simon

    2015-09-23

    A previously healthy 16-year-old girl presented with signs of acute hepatitis. On initial enquiry, she had not taken any prescribed or 'over-the-counter' medications, and there was no recent travel history. Further investigations revealed no viral, autoimmune or metabolic cause of hepatitis. Only following specific questioning did she reveal that she had, in the preceding 3 months, regularly consumed internet ordered Chinese green tea, which contained Camellia sinensis. After ceasing green tea consumption, there was a rapid and sustained recovery of her hepatitis. The authors discuss the probable cause of herbal tea in this case of acute hepatitis, and the importance of awareness of this rare yet recurring theme for patients and clinicians alike.

  20. Electrochemotherapy increases local control after incomplete excision of a recurring penile fibrosarcoma in a stallion

    PubMed Central

    Spugnini, E.P.; Bolaffio, C.; Scacco, L.; Baldi, A.

    2016-01-01

    An eleven-year-old stallion was referred for adjuvant treatment of an incompletely excised, recurring penile fibrosarcoma. The horse was bright, alert and responsive with a 15 x 12 cm ulcerated lesion on the ventral side of the penis. The lesion was the tumor bed of an incompletely excised fibrosarcoma. After complete staging procedures, the owner elected to treat the horse with electrochemotherapy (ECT) using cisplatin as chemotherapy agent. Two sessions of ECT were performed at two-week intervals using local cisplatin followed by trains of biphasic electric pulses applied using different electrodes until complete coverage of the area was achieved. The treatment was well tolerated, and the patient is still disease free after 12 months. ECT resulted in improved local control and should be considered among the available adjuvant treatments in equines carrying soft tissue tumors. PMID:27995080

  1. Discretization of Gene Expression Data Unmasks Molecular Subgroups Recurring in Different Human Cancer Types

    PubMed Central

    Soeldner, Robert; Egorov, Mark; Guenther, Rolf; Dehler, Silvia; Morys-Wortmann, Corinna; Moch, Holger; Henco, Karsten; Schraml, Peter

    2016-01-01

    Despite the individually different molecular alterations in tumors, the malignancy associated biological traits are strikingly similar. Results of a previous study using renal cell carcinoma (RCC) as a model pointed towards cancer-related features, which could be visualized as three groups by microarray based gene expression analysis. In this study, we used a mathematic model to verify the presence of these groups in RCC as well as in other cancer types. We developed an algorithm for gene-expression deviation profiling for analyzing gene expression data of a total of 8397 patients with 13 different cancer types and normal tissues. We revealed three common Cancer Transcriptomic Profiles (CTPs) which recurred in all investigated tumors. Additionally, CTPs remained robust regardless of the functions or numbers of genes analyzed. CTPs may represent common genetic fingerprints, which potentially reflect the closely related biological traits of human cancers. PMID:27537329

  2. Anomaly Analysis: NASA's Engineering and Safety Center Checks Recurring Shuttle Glitches

    NASA Technical Reports Server (NTRS)

    Morring, Frank, Jr.

    2004-01-01

    The NASA Engineering and Safety Center (NESC), set up in the wake of the Columbia accident to backstop engineers in the space shuttle program, is reviewing hundreds of recurring anomalies that the program had determined don't affect flight safety to see if in fact they might. The NESC is expanding its support to other programs across the agency, as well. The effort, which will later extend to the International Space Station (ISS), is a principal part of the attempt to overcome the normalization of deviance--a situation in which organizations proceeded as if nothing was wrong in the face of evidence that something was wrong--cited by sociologist Diane Vaughn as contributing to both space shuttle disasters.

  3. Recurring dominant-negative mutations in the AVP-NPII gene cause neurohypophyseal diabetes insipidus

    SciTech Connect

    Repaske, D.R.; Phillips, J.A.; Krishnamani, M.R.S.

    1994-09-01

    Autosomal dominant neurohypophyseal diabetes insipidus (ADNDI) is a familial form of arginine vasopressin (or antidiuretic hormone) deficiency that is usually manifest in early childhood with polyuria, polydipsia and an antidiuretic response to exogenous vasopressin or its analogs. The phenotype is postulated to arise from gliosis and depletion of the magnocellular neurons that produce vasopressin in the supraoptic and paraventricular nuclei of the hypothalamus. ADNDI is caused by heterozygosity for a variety of mutations in the AVP-NPII gene which encodes vasopressin, its carrier protein (NPII) and a glycoprotein (copeptin) of unknown function. These mutations include: (1) Ala 19{r_arrow}Thr (G279A) in AVP`s signal peptide, (2) Gly 17{r_arrow}Val (G1740T), (3) Pro 24{r_arrow}Leu (C1761T), (4) Gly 57{r_arrow}Ser (G1859A) and (5) del Glu 47({delta}AGG 1824-26), all of which occur in NPII. In characterizing the AVP-NPII mutations in five non-related ADNDI kindreds, we have detected two kindreds having mutation 1 (G279A), two having mutation 3 (C1761T) and one having mutation 4 (G1859A) without any other allelic changes being detected. Two of these recurring mutations (G279A and G1859A) are transitions that occur at CpG dinucleotides while the third (C1761T) does not. Interestingly, families with the same mutations differed in their ethnicity or in their affected AVP-NPII allele`s associated haplotype of closely linked DNA polymorphisms. Our data indicated that at least three of five known AVP-NPII mutations causing ADNDI tend to recur but the mechanisms by which these dominant-negative mutations cause variable or progressive expression of the ADNDI phenotype remain unclear.

  4. t(1;3)(p36;p21) is a recurring therapy-related translocation.

    PubMed

    Sato, Yuko; Izumi, Tohru; Kanamori, Hirakazu; Davis, Elizabeth M; Miura, Yasusada; Larson, Richard A; Le Beau, Michelle M; Ozawa, Keiya; Rowley, Janet D

    2002-06-01

    Chromosome bands 1p36 and 3p21 are known to be recurring breakpoints in therapy-related (t-) leukemia. We identified a recurring translocation, t(1;3)(p36;p21), in eight patients with various hematologic malignancies: three patients with ALL, one with chronic myelogenous leukemia (CML) in accelerated phase (AP), two with MDS, and two with AML(M3). Five of the eight patients had a history of chemotherapy, including alkylating agents in three, before the translocation was detected. In two of these five patients, the t(1;3)(p36;p21) emerged only at relapse or in the accelerated phase of CML. The karyotypes of the patients were complex, including -7 and structural abnormalities of 5q, 6q, 7q, 9p, and 11q23. Survival time varied among patients (25 days to more than 16 years). Using FISH with 13 1p35-36 cosmid probes (tel-FB12-CA5-G7-FD2-CB1-ED8-FD9-G32-AE3-G50-AD8-GG4-G43-cen), we delineated the 1p36 breakpoint in two patients with MDS and ALL as lying between FB12 and FD2 (between BAC47P3 and PAC963K15), with a small deletion near the breakpoint in both cases. In the patient with MDS, there was also a deletion at 3p21.3, as detected with the cosmid probe cosNRL9. The results of the present study suggest that t(1;3)(p36;p21) in hematologic diseases is associated with prior exposure to mutagens, including alkylating agents.

  5. The Hunt Opinion Model—An Agent Based Approach to Recurring Fashion Cycles

    PubMed Central

    Apriasz, Rafał; Krueger, Tyll; Marcjasz, Grzegorz; Sznajd-Weron, Katarzyna

    2016-01-01

    We study a simple agent-based model of the recurring fashion cycles in the society that consists of two interacting communities: “snobs” and “followers” (or “opinion hunters”, hence the name of the model). Followers conform to all other individuals, whereas snobs conform only to their own group and anticonform to the other. The model allows to examine the role of the social structure, i.e. the influence of the number of inter-links between the two communities, as well as the role of the stability of links. The latter is accomplished by considering two versions of the same model—quenched (parameterized by fraction L of fixed inter-links) and annealed (parameterized by probability p that a given inter-link exists). Using Monte Carlo simulations and analytical treatment (the latter only for the annealed model), we show that there is a critical fraction of inter-links, above which recurring cycles occur. For p ≤ 0.5 we derive a relation between parameters L and p that allows to compare both models and show that the critical value of inter-connections, p*, is the same for both versions of the model (annealed and quenched) but the period of a fashion cycle is shorter for the quenched model. Near the critical point, the cycles are irregular and a change of fashion is difficult to predict. For the annealed model we also provide a deeper theoretical analysis. We conjecture on topological grounds that the so-called saddle node heteroclinic bifurcation appears at p*. For p ≥ 0.5 we show analytically the existence of the second critical value of p, for which the system undergoes Hopf’s bifurcation. PMID:27835679

  6. The Hunt Opinion Model-An Agent Based Approach to Recurring Fashion Cycles.

    PubMed

    Apriasz, Rafał; Krueger, Tyll; Marcjasz, Grzegorz; Sznajd-Weron, Katarzyna

    2016-01-01

    We study a simple agent-based model of the recurring fashion cycles in the society that consists of two interacting communities: "snobs" and "followers" (or "opinion hunters", hence the name of the model). Followers conform to all other individuals, whereas snobs conform only to their own group and anticonform to the other. The model allows to examine the role of the social structure, i.e. the influence of the number of inter-links between the two communities, as well as the role of the stability of links. The latter is accomplished by considering two versions of the same model-quenched (parameterized by fraction L of fixed inter-links) and annealed (parameterized by probability p that a given inter-link exists). Using Monte Carlo simulations and analytical treatment (the latter only for the annealed model), we show that there is a critical fraction of inter-links, above which recurring cycles occur. For p ≤ 0.5 we derive a relation between parameters L and p that allows to compare both models and show that the critical value of inter-connections, p*, is the same for both versions of the model (annealed and quenched) but the period of a fashion cycle is shorter for the quenched model. Near the critical point, the cycles are irregular and a change of fashion is difficult to predict. For the annealed model we also provide a deeper theoretical analysis. We conjecture on topological grounds that the so-called saddle node heteroclinic bifurcation appears at p*. For p ≥ 0.5 we show analytically the existence of the second critical value of p, for which the system undergoes Hopf's bifurcation.

  7. Stereotactic Radiosurgery for Treatment of Spinal Metastases Recurring in Close Proximity to Previously Irradiated Spinal Cord

    SciTech Connect

    Choi, Clara Y.H.; Adler, John R.; Gibbs, Iris C.; Chang, Steven D.; Jackson, Paul S.; Minn, A. Yuriko; Lieberson, Robert E.; Soltys, Scott G.

    2010-10-01

    Purpose: As the spinal cord tolerance often precludes reirradiation with conventional techniques, local recurrence within a previously irradiated field presents a treatment challenge. Methods and Materials: We retrospectively reviewed 51 lesions in 42 patients treated from 2002 to 2008 whose spinal metastases recurred in a previous radiation field (median previous spinal cord dose of 40 Gy) and were subsequently treated with stereotactic radiosurgery (SRS). Results: SRS was delivered to a median marginal dose of 20 Gy (range, 10-30 Gy) in 1-5 fractions (median, 2), targeting a median tumor volume of 10.3 cm{sup 3} (range, 0.2-128.6 cm{sup 3}). Converting the SRS regimens with the linear quadratic model ({alpha}/{beta} = 3), the median spinal cord maximum single-session equivalent dose (SSED) was 12.1 Gy{sub 3} (range, 4.7-19.3 Gy{sub 3}). With a median follow-up of 7 months (range, 2-47 months), the Kaplan-Meier local control and overall survival rates at 6/12 months were 87%/73% and 81%/68%, respectively. A time to retreatment of {<=}12 months and the combination of time to retreatment of {<=}12 months with an SSED of <15 Gy{sub 10} were significant predictors of local failure on univariate and multivariate analyses. In patients with a retreatment interval of <12 months, 6/12 month local control rates were 88%/58%, with a SSED of >15 Gy{sub 10}, compared to 45%/0% with <15 Gy{sub 10}, respectively. One patient (2%) experienced Grade 4 neurotoxicity. Conclusion: SRS is safe and effective in the treatment of spinal metastases recurring in previously irradiated fields. Tumor recurrence within 12 months may correlate with biologic aggressiveness and require higher SRS doses (SSED >15 Gy{sub 10}). Further research is needed to define the partial volume retreatment tolerance of the spinal cord and the optimal target dose.

  8. Laboratory Simulations and Spectral Analyses of Recurring Slope Streaks on Mars

    NASA Astrophysics Data System (ADS)

    Wing, B.; Irvin, B.; Hibbitts, C.; Mushkin, A.

    2014-12-01

    Low albedo streaks on Martian slopes have been cited as possible evidence for present-day intermittent and repeated surface flow of water, or brine (Mushkin et al., 2010). Also termed as Recurring Slope Lineae (1), such streaks can grow, fade, and recur repeatedly on the same slopes. Although distinguishable by being darker than surrounding terrain slope streaks have no diagnostic spectral absorption features (2). A leading hypothesis is formation by multiple wetting and drying events. Laboratory investigations have previously explored this possibility (e.g 3). When wetted with brines, soils darken, but as the sample dries, it brightens again. Wetting also results in absorption bands near 1.5 and 2 microns, which are not detected in spectra of slope streaks. Additionally, dried brines of most salts such as MgSO4, or other sulfates and many chlorides are brighter than Martian soils. However, iron chlorides are a salt that have lower albedo than most other salts and may present a mechanism for darkening slope streaks without inducing a spectral absorption feature. To explore this hypothesis, we have begun to conduct experiments investigating the spectra of iron chloride chloride solutions wetting palagonite and subsequently drying under Martian atmospheric conditions. Preliminary experiments demonstrate that FeIII chloride dried onto palagonite has no absorption features in the NIR and SWIR and remains dark and red. However, these chlorides will oxidize under terrestrial conditions forming Fe2O3 as they dry. We have constructed an environmental chamber that mimics Martian oxygen fugacity though a combination of vacuum and N2 purging, allowing for sample wetting and drying while concurrently taking spectra from 0.4 to 2.4 microns. Results from this experimental setup under Martian atmospheric conditions will be presented. References: (1) McEwen et al., (2011) Science, 333, 740-743, (2) Mushkin et al., (2010) Geophys. Res. Lett., 37, L22201, doi: 10.1029/2010GL044535

  9. Decomposing Spatiotemporal Brain Patterns into Topographic Latent Sources

    PubMed Central

    Gershman, Samuel J.; Blei, David M.; Norman, Kenneth A.; Sederberg, Per B.

    2014-01-01

    This paper extends earlier work on spatial modeling of fMRI data to the temporal domain, providing a framework for analyzing high temporal resolution brain imaging modalities such as electroencapholography (EEG). The central idea is to decompose brain imaging data into a covariate-dependent superposition of functions defined over continuous time and space (what we refer to as topographic latent sources). The continuous formulation allows us to parametrically model spatiotemporally localized activations. To make group-level inferences, we elaborate the model hierarchically by sharing sources across subjects. We describe a variational algorithm for parameter estimation that scales efficiently to large data sets. Applied to three EEG data sets, we find that the model produces good predictive performance and reproduces a number of classic findings. Our results suggest that topographic latent sources serve as an effective hypothesis space for interpreting spatiotemporal brain imaging data. PMID:24791745

  10. STPMiner: A Highperformance Spatiotemporal Pattern Mining Toolbox

    SciTech Connect

    Vatsavai, Raju

    2011-01-01

    The volume of spatiotemporal data being generated from scientific simulations and observations from sensors is growing at an astronomical rate. This data explosion is going to pose three challenges to the existing data mining infrastructure: algorithmic, computational, and I/O. Over the years we have implemented several spatiotemporal data mining algorithms including: outliers/anomalies, colocation patterns, change patterns, clustering, classification, and prediction algorithms. In this paper we briefly discuss the core spatiotemporal pattern mining algorithms along with some of the computational and I/O challenges associated with the big data.

  11. Spatio-temporal representativeness of aerosol remote sensing observations

    NASA Astrophysics Data System (ADS)

    Schutgens, Nick; Gryspeerdt, Edward; Tsyro, Svetlana; Goto, Daisuke; Watson-Parris, Duncan; Weigum, Natalie; Schulz, Michael; Stier, Philip

    2016-04-01

    One characteristic of remote sensing observations is the strong intermittency with which they observe the same scene. Due to unfavourable conditions (due to e.g. low visible light, cloudiness or high surface albedo), sampling constraints (due to e.g. polar orbits) or instrument malfunction or maintenance, gaps in the observing record of hours to months exist. At the same time, satellite L3 products often are spatial aggregates over considerable distances (e.g. 1 by 1 degree). We study the impact of spatio-temporal sampling of observations on their representativeness: i.e. how well can satellite products represent the large scale (~ 100 by 100 km) aerosol field over periods of days, months, or years. This study was conducted by using diverse global and regional aerosol models as a truth and sub-sample them according to actual observations. In this way, we have been able to study the representativeness of different observing systems like MODIS, CALIOP and AERONET. Monthly and yearly averages allow serious sampling errors, that may still be present in multi-year climatologies due to recurring observing patterns. Even daily averages are affected as diurnal cycles can often not be observed. We discuss the implications these representativeness errors have for e.g. model evaluation or the construction of climatologies. We also assess similar representativeness issues in ground site in-situ observations from e.g. EMEP or IMPROVE and show that satellite datasets have distinct advantages due to their better spatial coverage provided temporal sampling is dealt with properly (i.e. through collocation of datasets). Finally, we briefly introduce a software tool (the Community Intercomparison Suite or CIS) that is designed to improve representativeness of datasets in intercomparion studies through aggregation and collocation of data.

  12. Artificial spatiotemporal touch inputs reveal complementary decoding in neocortical neurons

    PubMed Central

    Oddo, Calogero M.; Mazzoni, Alberto; Spanne, Anton; Enander, Jonas M. D.; Mogensen, Hannes; Bengtsson, Fredrik; Camboni, Domenico; Micera, Silvestro; Jörntell, Henrik

    2017-01-01

    Investigations of the mechanisms of touch perception and decoding has been hampered by difficulties in achieving invariant patterns of skin sensor activation. To obtain reproducible spatiotemporal patterns of activation of sensory afferents, we used an artificial fingertip equipped with an array of neuromorphic sensors. The artificial fingertip was used to transduce real-world haptic stimuli into spatiotemporal patterns of spikes. These spike patterns were delivered to the skin afferents of the second digit of rats via an array of stimulation electrodes. Combined with low-noise intra- and extracellular recordings from neocortical neurons in vivo, this approach provided a previously inaccessible high resolution analysis of the representation of tactile information in the neocortical neuronal circuitry. The results indicate high information content in individual neurons and reveal multiple novel neuronal tactile coding features such as heterogeneous and complementary spatiotemporal input selectivity also between neighboring neurons. Such neuronal heterogeneity and complementariness can potentially support a very high decoding capacity in a limited population of neurons. Our results also indicate a potential neuroprosthetic approach to communicate with the brain at a very high resolution and provide a potential novel solution for evaluating the degree or state of neurological disease in animal models. PMID:28374841

  13. CATchUP: A Web Database for Spatiotemporally Regulated Genes.

    PubMed

    Nakamura, Yukino; Kudo, Toru; Terashima, Shin; Saito, Misa; Nambara, Eiji; Yano, Kentaro

    2017-01-01

    For proper control of biological activity, some key genes are highly expressed in a particular spatiotemporal domain. Mining of such spatiotemporally expressed genes using large-scale gene expression data derived from a broad range of experimental sources facilitates our understanding of genome-scale functional gene networks. However, comprehensive information on spatiotemporally expressed genes is lacking in plants. To collect such information, we devised a new index, Δdmax, which is the maximum difference in relative gene expression levels between sample runs which are neighboring when sorted by the levels. Employing this index, we comprehensively evaluated transcripts using large-scale RNA sequencing (RNA-Seq) data stored in the Sequence Read Archive for eight plant species: Arabidopsis thaliana (Arabidopsis), Solanum lycopersicum (tomato), Solanum tuberosum (potato), Oryza sativa (rice), Sorghum bicolor (sorghum), Vitis vinifera (grape), Medicago truncatula (Medicago), and Glycine max (soybean). Based on the frequency distribution of the Δdmax values, approximately 70,000 transcripts showing 0.3 or larger Δdmax values were extracted for the eight species. Information on these genes including the Δdmax values, functional annotations, conservation among species, and experimental conditions where the genes show high expression levels is provided in a new database, CATchUP (http://plantomics.mind.meiji.ac.jp/CATchUP). The CATchUP database assists in identifying genes specifically expressed under particular conditions with powerful search functions and an intuitive graphical user interface.

  14. Spatiotemporal Bayesian inference dipole analysis for MEG neuroimaging data.

    PubMed

    Jun, Sung C; George, John S; Paré-Blagoev, Juliana; Plis, Sergey M; Ranken, Doug M; Schmidt, David M; Wood, C C

    2005-10-15

    Recently, we described a Bayesian inference approach to the MEG/EEG inverse problem that used numerical techniques to estimate the full posterior probability distributions of likely solutions upon which all inferences were based [Schmidt, D.M., George, J.S., Wood, C.C., 1999. Bayesian inference applied to the electromagnetic inverse problem. Human Brain Mapping 7, 195; Schmidt, D.M., George, J.S., Ranken, D.M., Wood, C.C., 2001. Spatial-temporal bayesian inference for MEG/EEG. In: Nenonen, J., Ilmoniemi, R. J., Katila, T. (Eds.), Biomag 2000: 12th International Conference on Biomagnetism. Espoo, Norway, p. 671]. Schmidt et al. (1999) focused on the analysis of data at a single point in time employing an extended region source model. They subsequently extended their work to a spatiotemporal Bayesian inference analysis of the full spatiotemporal MEG/EEG data set. Here, we formulate spatiotemporal Bayesian inference analysis using a multi-dipole model of neural activity. This approach is faster than the extended region model, does not require use of the subject's anatomical information, does not require prior determination of the number of dipoles, and yields quantitative probabilistic inferences. In addition, we have incorporated the ability to handle much more complex and realistic estimates of the background noise, which may be represented as a sum of Kronecker products of temporal and spatial noise covariance components. This reduces the effects of undermodeling noise. In order to reduce the rigidity of the multi-dipole formulation which commonly causes problems due to multiple local minima, we treat the given covariance of the background as uncertain and marginalize over it in the analysis. Markov Chain Monte Carlo (MCMC) was used to sample the many possible likely solutions. The spatiotemporal Bayesian dipole analysis is demonstrated using simulated and empirical whole-head MEG data.

  15. Rapid molecular diagnosis of the Mycobacterium tuberculosis Rangipo strain responsible for the largest recurring TB cluster in New Zealand.

    PubMed

    Mulholland, Claire V; Ruthe, Ali; Cursons, Ray T; Durrant, Robert; Karalus, Noel; Coley, Kathryn; Bower, James; Permina, Elizabeth; Coleman, Megan J; Roberts, Sally A; Arcus, Vickery L; Cook, Gregory M; Aung, Htin Lin

    2017-03-23

    Despite New Zealand being a low-tuberculosis (TB) burden country, there are disproportionately high rates of TB in particular populations. Here, we report a rapid molecular diagnosis of the Mycobacterium tuberculosis Rangipo strain responsible for the largest recurring TB cluster in New Zealand.

  16. 33 CFR 100.130 - Special Local Regulations; Recurring Annual Marine Events in Sector Boston Captain of the Port Zone.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...; Recurring Annual Marine Events in Sector Boston Captain of the Port Zone. 100.130 Section 100.130 Navigation... Sector Boston Captain of the Port Zone. This section applies to the marine events listed in Table 1 of... Guard Auxiliary, state, or local law enforcement vessels assigned or approved by the Captain of the...

  17. 33 CFR 100.130 - Special Local Regulations; Recurring Annual Marine Events in Sector Boston Captain of the Port Zone.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...; Recurring Annual Marine Events in Sector Boston Captain of the Port Zone. 100.130 Section 100.130 Navigation... Sector Boston Captain of the Port Zone. This section applies to the marine events listed in Table 1 of... Guard Auxiliary, state, or local law enforcement vessels assigned or approved by the Captain of the...

  18. Are Some Disabilities More Equal than Others? Conceptualising Fluctuating or Recurring Impairments within Contemporary Legislation and Practice

    ERIC Educational Resources Information Center

    Boyd, Vic

    2012-01-01

    In recent years, the concept of fluctuating or recurring impairments has grown both in the public consciousness as well as in frequency of note within policy documentation and legislation. However, contention still surrounds the perceived legitimacy of such impairments, including chronic fatigue syndrome/myalgic encephalomyelitis, epilepsy and…

  19. 75 FR 24799 - Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-06

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District; Correction ACTION... events in the Fifth Coast Guard District, one on April 17-18, 2010, and one on May 29-30, 2010....

  20. 76 FR 37293 - Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-27

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Special Local Regulation for Marine Events; Temporary Change of Dates for Recurring Marine Events in the Fifth Coast Guard District, John H. Kerr Reservoir... event in the Fifth Coast Guard District, specifically, the ``Clarksville Hydroplane...

  1. 78 FR 22777 - Special Local Regulations; Recurring Marine Events in the Seventh Coast Guard District; St. Croix...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-17

    ... SECURITY Coast Guard 33 CFR Part 100 Special Local Regulations; Recurring Marine Events in the Seventh Coast Guard District; St. Croix, U.S.V.I. AGENCY: Coast Guard, DHS. ACTION: Notice of enforcement of regulation. SUMMARY: The Coast Guard will enforce the special local regulation for the Ironman St. Croix...

  2. 75 FR 64670 - Safety Zones; Temporary Change of Date for Recurring Fireworks Display Within the Fifth Coast...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-20

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zones; Temporary Change of Date for Recurring Fireworks Display Within the Fifth Coast Guard District, Wrightsville Beach, NC AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard is temporarily changing the enforcement period...

  3. 77 FR 5463 - Safety Zones; Annually Recurring Marine Events in Coast Guard Southeastern New England Captain of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-03

    ... SECURITY Coast Guard 33 CFR Part 100 and 165 RIN 1625-AA08; AA00 Safety Zones; Annually Recurring Marine Events in Coast Guard Southeastern New England Captain of the Port Zone AGENCY: Coast Guard, DHS. ACTION: Notice of proposed rulemaking. SUMMARY: The Coast Guard proposes to amend special local regulations...

  4. 76 FR 30827 - Temporary Change of Dates for Recurring Marine Event in the Fifth Coast Guard District; Elizabeth...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-27

    ... SECURITY Coast Guard 33 CFR Part 100 RIN 1625-AA08 Temporary Change of Dates for Recurring Marine Event in the Fifth Coast Guard District; Elizabeth River, Norfolk, VA AGENCY: Coast Guard, DHS. ACTION: Temporary final rule. SUMMARY: The Coast Guard will temporarily change the enforcement period of...

  5. Spatiotemporally controlled single cell sonoporation

    PubMed Central

    Fan, Zhenzhen; Liu, Haiyan; Mayer, Michael; Deng, Cheri X.

    2012-01-01

    This paper presents unique approaches to enable control and quantification of ultrasound-mediated cell membrane disruption, or sonoporation, at the single-cell level. Ultrasound excitation of microbubbles that were targeted to the plasma membrane of HEK-293 cells generated spatially and temporally controlled membrane disruption with high repeatability. Using whole-cell patch clamp recording combined with fluorescence microscopy, we obtained time-resolved measurements of single-cell sonoporation and quantified the size and resealing rate of pores. We measured the intracellular diffusion coefficient of cytoplasmic RNA/DNA from sonoporation-induced transport of an intercalating fluorescent dye into and within single cells. We achieved spatiotemporally controlled delivery with subcellular precision and calcium signaling in targeted cells by selective excitation of microbubbles. Finally, we utilized sonoporation to deliver calcein, a membrane-impermeant substrate of multidrug resistance protein-1 (MRP1), into HEK-MRP1 cells, which overexpress MRP1, and monitored the calcein efflux by MRP1. This approach made it possible to measure the efflux rate in individual cells and to compare it directly to the efflux rate in parental control cells that do not express MRP1. PMID:23012425

  6. Spatiotemporal recurrences of sandpile avalanches

    NASA Astrophysics Data System (ADS)

    Tarun, Anjali B.; Paguirigan, Antonino A.; Batac, Rene C.

    2015-10-01

    We study the space and time properties of avalanches in a continuous sandpile model by constructing a temporally directed network linking together the recurrent avalanche events based on their spatial separation. We use two different criteria for network construction: a later event is connected to a previous one if it is either nearest or farthest from it among all the later events. With this, we observe scale-free regimes emerge as characterized by the following power-law exponents: (a) α = 1.7 for the avalanche size distributions; (b) βF = 2.1 in the in-degree distribution of farthest recurrences; (c) δ = 1 for the separation distances; and (d) γ = 1 for the temporal separations of recurrences. Our results agree with earlier observations that describe the sandpile avalanches as repulsive events, i.e. the next avalanche is more likely to be physically separated from an earlier one. These observations, which are not captured by usual interoccurrence statistics and by random connection mechanisms, suggest an underlying spatiotemporal organization in the sandpile that makes it useful for modeling real-world systems.

  7. Effects of recurring summer droughts on ecosystem photosynthesis and respiration in a mountain grassland

    NASA Astrophysics Data System (ADS)

    Schmitt, Michael; Ingrisch, Johannes; Sturm, Patrick; Ladreiter-Knauss, Thomas; Hasibeder, Roland; Bramboeck, Peter; Berger, Vanessa; Bahn, Michael

    2013-04-01

    Climatic changes in mountain regions play a key role in current and future grassland ecosystem processes. It is currently expected that droughts and heatwaves will become more frequent in a changing climate. All around the world mountain regions have been labelled as sensitive zones, where declining water availability and increasing temperature are expected to increase the vulnerability of these ecosystems. However, the effects of such extreme events on ecosystem carbon (C) fluxes and their coupling in temperate and so far non-water limited Alpine grasslands are not yet well understood. We studied effects of recurring summer drought on the C dynamics of a mountain meadow at 1820 m and an abandoned grassland at 2000 m in the Austrian Central Alps. The aim of the study was (1) to analyse the multiannual effect of drought on net ecosystem CO2 exchange (NEE) and its major component processes, i.e. gross primary productivity (GPP) and ecosystem respiration (Reco), and (2) to trace drought effects on the use of recent C in soil respiration. We tested the hypothesis that drought reduces NEE, GPP and Reco and the ratio of GPP / Reco and causes a reduction in the use of recent photoassimilates in belowground respiration. At each study site, exclusion of rainfall was achieved by establishing rain-out shelters for a period of two months (June, July), while control plots remained exposed to natural precipitation. To trace the fate of recent C from assimilation to respiration 13CO2 pulse-labelling was carried out at the meadow site, and the carbon isotope composition of soil respired CO2 was continuously monitored with an open dynamic-chamber system coupled with a quantum cascade laser. Our results showed that at both sites NEE, GPP and Reco showed a consistent reduction with reduction in soil water level. Drought reduced ecosystem respiration to a lesser extent than photosynthesis. We observed memory effects on all flux processes after 3 years of recurring drought on the

  8. Intravesical chemotherapy for intermediate risk non-muscle invasive bladder cancer recurring after a first cycle of intravesical adjuvant therapy

    PubMed Central

    Serretta, Vincenzo; Sommatino, Francesco; Gesolfo, Cristina Scalici; Franco, Vito; Cicero, Giuseppe; Allegro, Rosalinda

    2015-01-01

    Context: The therapeutic strategy in intermediate risk (IR) non-muscle invasive bladder cancer (NMIBC) recurring after intravesical therapy (IT) is not well defined. Most patients are usually retreated by Bacillus Calmette-Guerin (BCG). Aims: To evaluate the efficacy of intravesical chemotherapy (ICH) given at recurrence after the first cycle of ICH in IR-NMIBC recurring 6 months or later. Settings and Design: Retrospective analysis of the efficacy of ICH given after previous IT. Materials and Methods: The clinical files of IR-NMIBC patients recurring later than 6 months after transurethral resection (TUR) and IT and retreated by IT were reviewed. The patients should be at intermediate risk both initially and at the first recurrence. BCG should have been given at full dose. Cytology and cystoscopy were performed 3 monthly for 2 years and then 6 monthly. Statistical Analysis: The RFS was estimated by the Kaplan-Meier method and the differences between treatment groups were compared by log-rank test. Mann Whitney U-test was used to compare the parameters’ distribution for median time to recurrence. Multivariate Cox proportional hazards models were used. Results: The study included 179 patients. The first IT was ICH in 146 (81.6%) and BCG in 33 (18.4%), re-IT was ICH in 112 (62.6%) and BCG in 67 (37.4%) patients. Median time to recurrence was 18 and 16 months after first and second IT (P = 0.32). At 3 years, 24 (35.8%) and 49 (43.8%) patients recurred after BCG and ICH, respectively (P = 0.90). No difference in RFS was found between BCG and ICH given after a first cycle of ICH (P = 0.23). Conclusions: Re-treatment with ICH could represent a legitimate option to BCG in patients harboring IR-NMIBC recurring after TUR and previous ICH. Prospective trials are needed. PMID:25657538

  9. Enabling the Discovery of Recurring Anomalies in Aerospace System Problem Reports using High-Dimensional Clustering Techniques

    NASA Technical Reports Server (NTRS)

    Srivastava, Ashok, N.; Akella, Ram; Diev, Vesselin; Kumaresan, Sakthi Preethi; McIntosh, Dawn M.; Pontikakis, Emmanuel D.; Xu, Zuobing; Zhang, Yi

    2006-01-01

    This paper describes the results of a significant research and development effort conducted at NASA Ames Research Center to develop new text mining techniques to discover anomalies in free-text reports regarding system health and safety of two aerospace systems. We discuss two problems of significant importance in the aviation industry. The first problem is that of automatic anomaly discovery about an aerospace system through the analysis of tens of thousands of free-text problem reports that are written about the system. The second problem that we address is that of automatic discovery of recurring anomalies, i.e., anomalies that may be described m different ways by different authors, at varying times and under varying conditions, but that are truly about the same part of the system. The intent of recurring anomaly identification is to determine project or system weakness or high-risk issues. The discovery of recurring anomalies is a key goal in building safe, reliable, and cost-effective aerospace systems. We address the anomaly discovery problem on thousands of free-text reports using two strategies: (1) as an unsupervised learning problem where an algorithm takes free-text reports as input and automatically groups them into different bins, where each bin corresponds to a different unknown anomaly category; and (2) as a supervised learning problem where the algorithm classifies the free-text reports into one of a number of known anomaly categories. We then discuss the application of these methods to the problem of discovering recurring anomalies. In fact the special nature of recurring anomalies (very small cluster sizes) requires incorporating new methods and measures to enhance the original approach for anomaly detection. ?& pant 0-

  10. Spatio-temporal variability in ventricular fibrillation

    NASA Astrophysics Data System (ADS)

    Hastings, Harold M.; Evans, Steven J.; Fenton, Flavio H.; Garfinkel, Alan

    2001-03-01

    It is widely believed that reentrant ventricular tachycardia arises when a spiral wave of activation takes over and drives the ventricle at a rate significantly faster than sinus rhythm, and that ventricular fibrillation (VF), a spatio-temporally disorganized form of cardiac activity leading to sudden cardiac death, arises when this spiral breaks down into multiple offspring. Many authors have found that VF displays significant spatial and temporal organization. The purpose of this research is to quantify time scales and temporal and spatial variability in VF. Surface electrograms were obtained from a stable canine model of VF (cf. Nwasokwa and Bodenheimer, Am. J. Physiol. 253, H643 (1987)). These electrograms were analyzed to identify activation times to an accuracy of 1 ms (cf. Garfinkel et al., J. Clin. Invest. 99, 305 (1997)), yielded eighteen usable series, each containing over 1024 intervactivation intervals, two or three from widely spaced sites per episode of VF, 7 total episodes in 4 animals. Spatial and long-term (60 - 120 sec) temporal variability were analyzed and compared by ANOVA techniques (Evans et al., Proc. Royal Soc. B265, 2167 (1998)). In 6 of 7 episodes, spatial variability among sites was statistically more significant than variability between the first and second halves of each series. More recently, Fourier analysis of these series found three distinct scaling regions, with power law dynamics in each and break points of ca. 1 sec and 4 sec. Finally, there was significant variability in the fraction of "short" interactivation intervals (lasting < 60 of 125 ms) among sites. Together these results suggest variability in physiological properties among sites and consequent variability in spiral wave dynamics among sites.

  11. Lesser snow goose helminths show recurring and positive parasite infection-diversity relations.

    PubMed

    Dargent, Felipe; Morrill, André; Alisauskas, Ray T; McLaughlin, J Daniel; Shutler, Dave; Forbes, Mark R

    2017-04-01

    The patterns and mechanisms by which biological diversity is associated with parasite infection risk are important to study because of their potential implications for wildlife population's conservation and management. Almost all research in this area has focused on host species diversity and has neglected parasite diversity, despite evidence that parasites are important drivers of community structure and ecosystem processes. Here, we assessed whether presence or abundance of each of nine helminth species parasitizing lesser snow geese (Chen caerulescens) was associated with indices of parasite diversity (i.e. species richness and Shannon's Diversity Index). We found repeated instances of focal parasite presence and abundance having significant positive co-variation with diversity measures of other parasites. These results occurred both within individual samples and for combinations of all samples. Whereas host condition and parasite facilitation could be drivers of the patterns we observed, other host- or parasite-level effects, such as age or sex class of host or taxon of parasite, were discounted as explanatory variables. Our findings of recurring and positive associations between focal parasite abundance and diversity underscore the importance of moving beyond pairwise species interactions and contexts, and of including the oft-neglected parasite species diversity in infection-diversity studies.

  12. Recurring staphylococcal scalded skin syndrome in a very low birth weight infant: a case report

    PubMed Central

    2009-01-01

    Introduction Staphylococcal scalded skin syndrome is an extensive desquamative erythematous condition caused by exfoliative toxins of Staphylococcus aureus. This disease usually affects neonates and generally responds rapidly to antibiotic therapy. Case presentation We describe the case of a premature baby boy, weighing 1030 g, born after 26 6/7 weeks gestation, who developed two episodes of Staphylococcal scalded skin syndrome on days 19 and 48 of life. Cultures obtained during the first period did not reveal Staphylococcus aureus, but diagnosis was based on typical clinical grounds. Although the initial diagnosis was irritation by the fixation material of a nasal continuous positive airway pressure tube, the infant showed rapidly progressing skin blistering and exfoliation, characteristic of Staphylococcal scalded skin syndrome. After administration of antibiotic treatment, complete recovery was seen. In the second period, diagnosis of Staphylococcal scalded skin syndrome was made clinically and confirmed by results of microbiologic investigations. Staphylococcus aureus was cultured from the nose, skin lesions and the pharynx. The strain appeared to produce exfoliative toxin A. The clinical response to similar antibiotic treatment was identical to the first period of Staphylococcal scalded skin syndrome. Conclusion This case report discusses an unusual presentation of recurring Staphylococcal scalded skin syndrome in a baby with a very low birth weight. PMID:19830179

  13. Structural motifs recurring in different folds recognize the same ligand fragments

    PubMed Central

    Ausiello, Gabriele; Gherardini, Pier Federico; Gatti, Elena; Incani, Ottaviano; Helmer-Citterich, Manuela

    2009-01-01

    Background The structural analysis of protein ligand binding sites can provide information relevant for assigning functions to unknown proteins, to guide the drug discovery process and to infer relations among distant protein folds. Previous approaches to the comparative analysis of binding pockets have usually been focused either on the ligand or the protein component. Even though several useful observations have been made with these approaches they both have limitations. In the former case the analysis is restricted to binding pockets interacting with similar ligands, while in the latter it is difficult to systematically check whether the observed structural similarities have a functional significance. Results Here we propose a novel methodology that takes into account the structure of both the binding pocket and the ligand. We first look for local similarities in a set of binding pockets and then check whether the bound ligands, even if completely different, share a common fragment that can account for the presence of the structural motif. Thanks to this method we can identify structural motifs whose functional significance is explained by the presence of shared features in the interacting ligands. Conclusion The application of this method to a large dataset of binding pockets allows the identification of recurring protein motifs that bind specific ligand fragments, even in the context of molecules with a different overall structure. In addition some of these motifs are present in a high number of evolutionarily unrelated proteins. PMID:19527512

  14. Spatiotemporal dynamics of word processing in the human brain.

    PubMed

    Canolty, Ryan T; Soltani, Maryam; Dalal, Sarang S; Edwards, Erik; Dronkers, Nina F; Nagarajan, Srikantan S; Kirsch, Heidi E; Barbaro, Nicholas M; Knight, Robert T

    2007-11-01

    We examined the spatiotemporal dynamics of word processing by recording the electrocorticogram (ECoG) from the lateral frontotemporal cortex of neurosurgical patients chronically implanted with subdural electrode grids. Subjects engaged in a target detection task where proper names served as infrequent targets embedded in a stream of task-irrelevant verbs and nonwords. Verbs described actions related to the hand (e.g, throw) or mouth (e.g., blow), while unintelligible nonwords were sounds which matched the verbs in duration, intensity, temporal modulation, and power spectrum. Complex oscillatory dynamics were observed in the delta, theta, alpha, beta, low, and high gamma (HG) bands in response to presentation of all stimulus types. HG activity (80-200 Hz) in the ECoG tracked the spatiotemporal dynamics of word processing and identified a network of cortical structures involved in early word processing. HG was used to determine the relative onset, peak, and offset times of local cortical activation during word processing. Listening to verbs compared to nonwords sequentially activates first the posterior superior temporal gyrus (post-STG), then the middle superior temporal gyrus (mid-STG), followed by the superior temporal sulcus (STS). We also observed strong phase-locking between pairs of electrodes in the theta band, with weaker phase-locking occurring in the delta, alpha, and beta frequency ranges. These results provide details on the first few hundred milliseconds of the spatiotemporal evolution of cortical activity during word processing and provide evidence consistent with the hypothesis that an oscillatory hierarchy coordinates the flow of information between distinct cortical regions during goal-directed behavior.

  15. Mercury Toolset for Spatiotemporal Metadata

    NASA Astrophysics Data System (ADS)

    Devarakonda, Ranjeet; Palanisamy, Giri; Green, James; Wilson, Bruce; Rhyne, B. Timothy; Lindsley, Chris

    2010-06-01

    Mercury (http://mercury.ornl.gov) is a set of tools for federated harvesting, searching, and retrieving metadata, particularly spatiotemporal metadata. Version 3.0 of the Mercury toolset provides orders of magnitude improvements in search speed, support for additional metadata formats, integration with Google Maps for spatial queries, facetted type search, support for RSS (Really Simple Syndication) delivery of search results, and enhanced customization to meet the needs of the multiple projects that use Mercury. It provides a single portal to very quickly search for data and information contained in disparate data management systems, each of which may use different metadata formats. Mercury harvests metadata and key data from contributing project servers distributed around the world and builds a centralized index. The search interfaces then allow the users to perform a variety of fielded, spatial, and temporal searches across these metadata sources. This centralized repository of metadata with distributed data sources provides extremely fast search results to the user, while allowing data providers to advertise the availability of their data and maintain complete control and ownership of that data. Mercury periodically (typically daily)harvests metadata sources through a collection of interfaces and re-indexes these metadata to provide extremely rapid search capabilities, even over collections with tens of millions of metadata records. A number of both graphical and application interfaces have been constructed within Mercury, to enable both human users and other computer programs to perform queries. Mercury was also designed to support multiple different projects, so that the particular fields that can be queried and used with search filters are easy to configure for each different project.

  16. Mercury Toolset for Spatiotemporal Metadata

    NASA Technical Reports Server (NTRS)

    Wilson, Bruce E.; Palanisamy, Giri; Devarakonda, Ranjeet; Rhyne, B. Timothy; Lindsley, Chris; Green, James

    2010-01-01

    Mercury (http://mercury.ornl.gov) is a set of tools for federated harvesting, searching, and retrieving metadata, particularly spatiotemporal metadata. Version 3.0 of the Mercury toolset provides orders of magnitude improvements in search speed, support for additional metadata formats, integration with Google Maps for spatial queries, facetted type search, support for RSS (Really Simple Syndication) delivery of search results, and enhanced customization to meet the needs of the multiple projects that use Mercury. It provides a single portal to very quickly search for data and information contained in disparate data management systems, each of which may use different metadata formats. Mercury harvests metadata and key data from contributing project servers distributed around the world and builds a centralized index. The search interfaces then allow the users to perform a variety of fielded, spatial, and temporal searches across these metadata sources. This centralized repository of metadata with distributed data sources provides extremely fast search results to the user, while allowing data providers to advertise the availability of their data and maintain complete control and ownership of that data. Mercury periodically (typically daily) harvests metadata sources through a collection of interfaces and re-indexes these metadata to provide extremely rapid search capabilities, even over collections with tens of millions of metadata records. A number of both graphical and application interfaces have been constructed within Mercury, to enable both human users and other computer programs to perform queries. Mercury was also designed to support multiple different projects, so that the particular fields that can be queried and used with search filters are easy to configure for each different project.

  17. Neural method of spatiotemporal filter design

    NASA Astrophysics Data System (ADS)

    Szostakowski, Jaroslaw

    1997-10-01

    There is a lot of applications in medical imaging, computer vision, and the communications, where the video processing is critical. Although many techniques have been successfully developed for the filtering of the still-images, significantly fewer techniques have been proposed for the filtering of noisy image sequences. In this paper the novel approach to spatio- temporal filtering design is proposed. The multilayer perceptrons and functional-link nets are used for the 3D filtering. The spatio-temporal patterns are creating from real motion video images. The neural networks learn these patterns. The perceptrons with different number of layers and neurons in each layer are tested. Also, the different input functions in functional- link net are searched. The practical examples of the filtering are shown and compared with traditional (non-neural) spatio-temporal methods. The results are very interesting and the neural spatio-temporal filters seems to be very efficient tool for video noise reduction.

  18. Asteroid 2015 DB216: a recurring co-orbital companion to Uranus

    NASA Astrophysics Data System (ADS)

    de la Fuente Marcos, C.; de la Fuente Marcos, R.

    2015-10-01

    Minor bodies trapped in 1:1 co-orbital resonances with a host planet could be relevant to explain the origin of captured satellites. Among the giant planets, Uranus has one of the smallest known populations of co-orbitals, three objects, and all of them are short-lived. Asteroid 2015 DB216 has an orbital period that matches well that of Uranus, and here we investigate its dynamical state. Direct N-body calculations are used to assess the current status of this object, reconstruct its immediate dynamical past, and explore its future orbital evolution. A covariance matrix-based Monte Carlo scheme is presented and applied to study its short-term stability. We find that 2015 DB216 is trapped in a temporary co-orbital resonance with Uranus, the fourth known minor body to do so. A detailed analysis of its dynamical evolution shows that it is an unstable but recurring co-orbital companion to Uranus. It currently follows an asymmetric horseshoe trajectory that will last for at least 10 kyr, but it may remain inside Uranus' co-orbital zone for millions of years. As in the case of other transient Uranian co-orbitals, complex multibody ephemeral mean motion resonances trigger the switching between the various resonant co-orbital states. The new Uranian co-orbital exhibits a secular behaviour markedly different from that of the other known Uranian co-orbitals because of its higher inclination, nearly 38°. Given its rather unusual discovery circumstances, the presence of 2015 DB216 hints at the existence of a relatively large population of objects moving in similar orbits.

  19. Ocean time-series reveals recurring seasonal patterns of virioplankton dynamics in the northwestern Sargasso Sea

    PubMed Central

    Parsons, Rachel J; Breitbart, Mya; Lomas, Michael W; Carlson, Craig A

    2012-01-01

    There are an estimated 1030 virioplankton in the world oceans, the majority of which are phages (viruses that infect bacteria). Marine phages encompass enormous genetic diversity, affect biogeochemical cycling of elements, and partially control aspects of prokaryotic production and diversity. Despite their importance, there is a paucity of data describing virioplankton distributions over time and depth in oceanic systems. A decade of high-resolution time-series data collected from the upper 300 m in the northwestern Sargasso Sea revealed recurring temporal and vertical patterns of virioplankton abundance in unprecedented detail. An annual virioplankton maximum developed between 60 and 100 m during periods of summer stratification and eroded during winter convective mixing. The timing and vertical positioning of this seasonal pattern was related to variability in water column stability and the dynamics of specific picophytoplankton and heterotrophic bacterioplankton lineages. Between 60 and 100 m, virioplankton abundance was negatively correlated to the dominant heterotrophic bacterioplankton lineage SAR11, as well as the less abundant picophytoplankton, Synechococcus. In contrast, virioplankton abundance was positively correlated to the dominant picophytoplankton lineage Prochlorococcus, and the less abundant alpha-proteobacteria, Rhodobacteraceae. Seasonally, virioplankton abundances were highly synchronous with Prochlorococcus distributions and the virioplankton to Prochlorococcus ratio remained remarkably constant during periods of water column stratification. The data suggest that a significant fraction of viruses in the mid-euphotic zone of the subtropical gyres may be cyanophages and patterns in their abundance are largely determined by Prochlorococcus dynamics in response to water column stability. This high-resolution, decadal survey of virioplankton abundance provides insight into the possible controls of virioplankton dynamics in the open ocean

  20. Ocean time-series reveals recurring seasonal patterns of virioplankton dynamics in the northwestern Sargasso Sea.

    PubMed

    Parsons, Rachel J; Breitbart, Mya; Lomas, Michael W; Carlson, Craig A

    2012-02-01

    There are an estimated 10(30) virioplankton in the world oceans, the majority of which are phages (viruses that infect bacteria). Marine phages encompass enormous genetic diversity, affect biogeochemical cycling of elements, and partially control aspects of prokaryotic production and diversity. Despite their importance, there is a paucity of data describing virioplankton distributions over time and depth in oceanic systems. A decade of high-resolution time-series data collected from the upper 300 m in the northwestern Sargasso Sea revealed recurring temporal and vertical patterns of virioplankton abundance in unprecedented detail. An annual virioplankton maximum developed between 60 and 100 m during periods of summer stratification and eroded during winter convective mixing. The timing and vertical positioning of this seasonal pattern was related to variability in water column stability and the dynamics of specific picophytoplankton and heterotrophic bacterioplankton lineages. Between 60 and 100 m, virioplankton abundance was negatively correlated to the dominant heterotrophic bacterioplankton lineage SAR11, as well as the less abundant picophytoplankton, Synechococcus. In contrast, virioplankton abundance was positively correlated to the dominant picophytoplankton lineage Prochlorococcus, and the less abundant alpha-proteobacteria, Rhodobacteraceae. Seasonally, virioplankton abundances were highly synchronous with Prochlorococcus distributions and the virioplankton to Prochlorococcus ratio remained remarkably constant during periods of water column stratification. The data suggest that a significant fraction of viruses in the mid-euphotic zone of the subtropical gyres may be cyanophages and patterns in their abundance are largely determined by Prochlorococcus dynamics in response to water column stability. This high-resolution, decadal survey of virioplankton abundance provides insight into the possible controls of virioplankton dynamics in the open ocean.

  1. Spatiotemporal chaos in Easter Island ecology.

    PubMed

    Sprott, J C

    2012-10-01

    This paper demonstrates that a recently proposed spatiotemporal model for the ecology of Easter Island admits periodic and chaotic attractors, not previously reported. Such behavior may more realistically depict the population dynamics of general ecosystems and illustrates the power of simple models to produce the kind of complex behavior that is ubiquitous in such systems.

  2. Analysis of spatiotemporal signals of complex systems

    NASA Astrophysics Data System (ADS)

    Uhl, C.; Friedrich, R.; Haken, H.

    1995-05-01

    We present a method of analyzing spatiotemporal signals emerging from nonequilibrium self-organizing systems that are close to instability. The algorithm aims at an identification of spatial modes and corresponding order-parameter equations. We discuss and demonstrate the method by examples of simulated codimension I and II instabilities, including a numerically integrated partial differential equation leading to ``blinking states.''

  3. Spatio-temporal current density reconstruction (stCDR) from EEG/MEG-data.

    PubMed

    Darvas, F; Schmitt, U; Louis, A K; Fuchs, M; Knoll, G; Buchner, H

    2001-01-01

    Among the different approaches to the bioelectromagnetic inverse problem, the current-density reconstruction methods (CDR) provide the most general solutions. Since the inverse problem does not have a unique solution, model assumptions have to be taken into account. Multi-channel measurements contain not only spatial, but also temporal information about the sources, so a naturally extension to existing methods leads to spatio-temporal model constraints. Spatio-temporal CDR's (stCDR) have been tested in simplified volume conductor models, assuming different spatial model constraints and a smooth temporal activation model. Comparison to existing spatial model constraints showed a significant improvement of spatial and temporal resolution of the reconstructed sources for the spatio-temporal models especial in noisy data.

  4. Bandwidth and Noise in Spatiotemporally Modulated Mueller Matrix Polarimeters

    NASA Astrophysics Data System (ADS)

    Vaughn, Israel Jacob

    Polarimetric systems design has seen recent utilization of linear systems theory for system descriptions. Although noise optimal systems have been shown, bandwidth performance has not been addressed in depth generally and is particularly lacking for Mueller matrix (active) polarimetric systems. Bandwidth must be considered in a systematic way for remote sensing polarimetric systems design. The systematic approach facilitates both understanding of fundamental constraints and design of higher bandwidth polarimetric systems. Fundamental bandwidth constraints result in production of polarimetric "artifacts" due to channel crosstalk upon Mueller matrix reconstruction. This dissertation analyzes bandwidth trade-offs in spatio-temporal channeled Mueller matrix polarimetric systems. Bandwidth is directly related to the geometric positioning of channels in the Fourier (channel) space, however channel positioning for polarimetric systems is constrained both physically and by design parameters like domain separability. We present the physical channel constraints and the constraints imposed when the carriers are separable between space and time. Polarimetric systems are also constrained by noise performance, and there is a trade-off between noise performance and bandwidth. I develop cost functions which account for the trade-off between noise and bandwidth for spatio-temporal polarimetric systems. The cost functions allow a systems designer to jointly optimize systems with good bandwidth and noise performance. Optimization is implemented for a candidate spatio-temporal system design, and high temporal bandwidth systems resulting from the optimization are presented. Systematic errors which impact the bandwidth performance and mitigation strategies for these systematic errors are also presented. Finally, a portable imaging Mueller matrix system is built and analyzed based on the theoretical bandwidth analysis and system bandwidth optimization. Temporal bandwidth performance is

  5. Spatio-Temporal Updating in the Left Posterior Parietal Cortex

    PubMed Central

    Wada, Makoto; Takano, Kouji; Ikegami, Shiro; Ora, Hiroki; Spence, Charles; Kansaku, Kenji

    2012-01-01

    Adopting an unusual posture can sometimes give rise to paradoxical experiences. For example, the subjective ordering of successive unseen tactile stimuli delivered to the two arms can be affected when people cross them. A growing body of evidence now highlights the role played by the parietal cortex in spatio-temporal information processing when sensory stimuli are delivered to the body or when actions are executed; however, little is known about the neural basis of such paradoxical feelings resulting from such unusual limb positions. Here, we demonstrate increased fMRI activation in the left posterior parietal cortex when human participants adopted a crossed hands posture with their eyes closed. Furthermore, by assessing tactile temporal order judgments (TOJs) in the same individuals, we observed a positive association between activity in this area and the degree of reversal in TOJs resulting from crossing arms. The strongest positive association was observed in the left intraparietal sulcus. This result implies that the left posterior parietal cortex may be critically involved in monitoring limb position and in spatio-temporal binding when serial events are delivered to the limbs. PMID:22768126

  6. Cortical Spatio-Temporal Dynamics Underlying Phonological Target Detection in Humans

    ERIC Educational Resources Information Center

    Chang, Edward F.; Edwards, Erik; Nagarajan, Srikantan S.; Fogelson, Noa; Dalal, Sarang S.; Canolty, Ryan T.; Kirsch, Heidi E.; Barbaro, Nicholas M.; Knight, Robert T.

    2011-01-01

    Selective processing of task-relevant stimuli is critical for goal-directed behavior. We used electrocorticography to assess the spatio-temporal dynamics of cortical activation during a simple phonological target detection task, in which subjects press a button when a prespecified target syllable sound is heard. Simultaneous surface potential…

  7. Spatiotemporal Processing in Crossmodal Interactions for Perception of the External World: A Review

    PubMed Central

    Hidaka, Souta; Teramoto, Wataru; Sugita, Yoichi

    2015-01-01

    Research regarding crossmodal interactions has garnered much interest in the last few decades. A variety of studies have demonstrated that multisensory information (vision, audition, tactile sensation, and so on) can perceptually interact with each other in the spatial and temporal domains. Findings regarding crossmodal interactions in the spatiotemporal domain (i.e., motion processing) have also been reported, with updates in the last few years. In this review, we summarize past and recent findings on spatiotemporal processing in crossmodal interactions regarding perception of the external world. A traditional view regarding crossmodal interactions holds that vision is superior to audition in spatial processing, but audition is dominant over vision in temporal processing. Similarly, vision is considered to have dominant effects over the other sensory modalities (i.e., visual capture) in spatiotemporal processing. However, recent findings demonstrate that sound could have a driving effect on visual motion perception. Moreover, studies regarding perceptual associative learning reported that, after association is established between a sound sequence without spatial information and visual motion information, the sound sequence could trigger visual motion perception. Other sensory information, such as motor action or smell, has also exhibited similar driving effects on visual motion perception. Additionally, recent brain imaging studies demonstrate that similar activation patterns could be observed in several brain areas, including the motion processing areas, between spatiotemporal information from different sensory modalities. Based on these findings, we suggest that multimodal information could mutually interact in spatiotemporal processing in the percept of the external world and that common perceptual and neural underlying mechanisms would exist for spatiotemporal processing. PMID:26733827

  8. Termites promote resistance of decomposition to spatiotemporal variability in rainfall.

    PubMed

    Veldhuis, Michiel P; Laso, Francisco J; Olff, Han; Berg, Matty P

    2017-02-01

    The ecological impact of rapid environmental change will depend on the resistance of key ecosystems processes, which may be promoted by species that exert strong control over local environmental conditions. Recent theoretical work suggests that macrodetritivores increase the resistance of African savanna ecosystems to changing climatic conditions, but experimental evidence is lacking. We examined the effect of large fungus-growing termites and other non-fungus-growing macrodetritivores on decomposition rates empirically with strong spatiotemporal variability in rainfall and temperature. Non-fungus-growing larger macrodetritivores (earthworms, woodlice, millipedes) promoted decomposition rates relative to microbes and small soil fauna (+34%) but both groups reduced their activities with decreasing rainfall. However, fungus-growing termites increased decomposition rates strongest (+123%) under the most water-limited conditions, making overall decomposition rates mostly independent from rainfall. We conclude that fungus-growing termites are of special importance in decoupling decomposition rates from spatiotemporal variability in rainfall due to the buffered environment they create within their extended phenotype (mounds), that allows decomposition to continue when abiotic conditions outside are less favorable. This points at a wider class of possibly important ecological processes, where soil-plant-animal interactions decouple ecosystem processes from large-scale climatic gradients. This may strongly alter predictions from current climate change models.

  9. Mining Spatiotemporal Patterns of the Elder's Daily Movement

    NASA Astrophysics Data System (ADS)

    Chen, C. R.; Chen, C. F.; Liu, M. E.; Tsai, S. J.; Son, N. T.; Kinh, L. V.

    2016-06-01

    With rapid developments in wearable device technology, a vast amount of spatiotemporal data, such as people's movement and physical activities, are generated. Information derived from the data reveals important knowledge that can contribute a long-term care and psychological assessment of the elders' living condition especially in long-term care institutions. This study aims to develop a method to investigate the spatial-temporal movement patterns of the elders with their outdoor trajectory information. To achieve the goal, GPS based location data of the elderly subjects from long-term care institutions are collected and analysed with geographic information system (GIS). A GIS statistical model is developed to mine the elderly subjects' spatiotemporal patterns with the location data and represent their daily movement pattern at particular time. The proposed method first finds the meaningful trajectory and extracts the frequent patterns from the time-stamp location data. Then, a density-based clustering method is used to identify the major moving range and the gather/stay hotspot in both spatial and temporal dimensions. The preliminary results indicate that the major moving area of the elderly people encompasses their dorm and has a short moving distance who often stay in the same site. Subjects' outdoor appearance are corresponded to their life routine. The results can be useful for understanding elders' social network construction, risky area identification and medical care monitoring.

  10. Spatiotemporal Control of Supramolecular Self-Assembly and Function.

    PubMed

    Zhan, Jie; Cai, Yanbin; Ji, Shenglu; He, Shuangshuang; Cao, Yi; Ding, Dan; Wang, Ling; Yang, Zhimou

    2017-03-09

    The enzyme-triggered self-assembly of peptides has flourished in controlling the self-assembly kinetics and producing nanostructures that are typically inaccessible by conventional self-assembly pathways. However, the diffusion and nanoscale chemical gradient of self-assembling peptides generated by the enzyme also significantly affect the outcome of self-assembly, which has not been reported yet. In this work, we demonstrated for the first time a spatiotemporal control of enzyme-triggered peptide self-assembly. By simply adjusting the temperature, we could change both the catalytic activity of the enzyme of phosphatase and their aggregation states. The strategy kinetically controls the production rate of self-assembling peptides and spatially controls their distribution in the system, leading to the formation of nanoparticles at 37 °C and nanofibers at 4 °C. The nanofibers showed ∼10 times higher cellular uptake by 3T3 cells than the nanoparticles, thanks to their higher stability and more ordered structures. Using such spatiotemporal control, we could prepare optimized nanoprobes with low background fluorescence, rapid and high cellular uptake, and high sensitivity. We postulate that this strategy would be very useful in general for preparing self-assembled nanomaterials with controllable morphology and function.

  11. Cell Population Tracking and Lineage Construction with Spatiotemporal Context 1

    PubMed Central

    Li, Kang; Chen, Mei; Kanade, Takeo; Miller, Eric D.; Weiss, Lee E.; Campbell, Phil G.

    2008-01-01

    Automated visual-tracking of cell populations in vitro using phase contrast time-lapse microscopy enables quantitative, systematic and high-throughput measurements of cell behaviors. These measurements include the spatiotemporal quantification of cell migration, mitosis, apoptosis, and the construction of cell lineages. The combination of low signal-to-noise ratio of phase contrast microscopy images, high and varying densities of the cell cultures, topological complexities of cell shapes, and wide range of cell behaviors pose many challenges to existing tracking techniques. This paper presents a fully-automated multi-target tracking system that can efficiently cope with these challenges while simultaneously tracking and analyzing thousands of cells observed using time-lapse phase contrast microscopy. The system combines bottom-up and top-down image analysis by integrating multiple collaborative modules, which exploit a fast geometric active contour tracker in conjunction with adaptive interacting multiple models (IMM) motion filtering and spatiotemporal trajectory optimization. The system, which was tested using a variety of cell populations, achieved tracking accuracy in the range of 86.9%–92.5%. PMID:18656418

  12. Unique spatiotemporal requirements for intraflagellar transport genes during forebrain development

    PubMed Central

    Chang, Ching-Fang; Cionni, Megan; Brugmann, Samantha A.

    2017-01-01

    Primary cilia are organelles extended from virtually all cells and are required for the proper regulation of a number of canonical developmental pathways. The role in cortical development of proteins important for ciliary form and function is a relatively understudied area. Here we have taken a genetic approach to define the role in forebrain development of three intraflagellar transport proteins known to be important for primary cilia function. We have genetically ablated Kif3a, Ift88, and Ttc21b in a series of specific spatiotemporal domains. The resulting phenotypes allow us to draw several conclusions. First, we conclude that the Ttc21b cortical phenotype is not due to the activity of Ttc21b within the brain itself. Secondly, some of the most striking phenotypes are from ablations in the neural crest cells and the adjacent surface ectoderm indicating that cilia transduce critical tissue—tissue interactions in the developing embryonic head. Finally, we note striking differences in phenotypes from ablations only one embryonic day apart, indicating very discrete spatiotemporal requirements for these three genes in cortical development. PMID:28291836

  13. Mining spatiotemporal patterns of urban dwellers from taxi trajectory data

    NASA Astrophysics Data System (ADS)

    Mao, Feng; Ji, Minhe; Liu, Ting

    2016-06-01

    With the widespread adoption of locationaware technology, obtaining long-sequence, massive and high-accuracy spatiotemporal trajectory data of individuals has become increasingly popular in various geographic studies. Trajectory data of taxis, one of the most widely used inner-city travel modes, contain rich information about both road network traffic and travel behavior of passengers. Such data can be used to study the microscopic activity patterns of individuals as well as the macro system of urban spatial structures. This paper focuses on trajectories obtained from GPS-enabled taxis and their applications for mining urban commuting patterns. A novel approach is proposed to discover spatiotemporal patterns of household travel from the taxi trajectory dataset with a large number of point locations. The approach involves three critical steps: spatial clustering of taxi origin-destination (OD) based on urban traffic grids to discover potentially meaningful places, identifying threshold values from statistics of the OD clusters to extract urban jobs-housing structures, and visualization of analytic results to understand the spatial distribution and temporal trends of the revealed urban structures and implied household commuting behavior. A case study with a taxi trajectory dataset in Shanghai, China is presented to demonstrate and evaluate the proposed method.

  14. Spatiotemporal video segmentation based on graphical models.

    PubMed

    Wang, Yang; Loe, Kia-Fock; Tan, Tele; Wu, Jian-Kang

    2005-07-01

    This paper proposes a probabilistic framework for spatiotemporal segmentation of video sequences. Motion information, boundary information from intensity segmentation, and spatial connectivity of segmentation are unified in the video segmentation process by means of graphical models. A Bayesian network is presented to model interactions among the motion vector field, the intensity segmentation field, and the video segmentation field. The notion of the Markov random field is used to encourage the formation of continuous regions. Given consecutive frames, the conditional joint probability density of the three fields is maximized in an iterative way. To effectively utilize boundary information from the intensity segmentation, distance transformation is employed in local objective functions. Experimental results show that the method is robust and generates spatiotemporally coherent segmentation results. Moreover, the proposed video segmentation approach can be viewed as the compromise of previous motion based approaches and region merging approaches.

  15. What Is Spatio-Temporal Data Warehousing?

    NASA Astrophysics Data System (ADS)

    Vaisman, Alejandro; Zimányi, Esteban

    In the last years, extending OLAP (On-Line Analytical Processing) systems with spatial and temporal features has attracted the attention of the GIS (Geographic Information Systems) and database communities. However, there is no a commonly agreed definition of what is a spatio-temporal data warehouse and what functionality such a data warehouse should support. Further, the solutions proposed in the literature vary considerably in the kind of data that can be represented as well as the kind of queries that can be expressed. In this paper we present a conceptual framework for defining spatio-temporal data warehouses using an extensible data type system. We also define a taxonomy of different classes of queries of increasing expressive power, and show how to express such queries using an extension of the tuple relational calculus with aggregated functions.

  16. Nonlinear Analysis of Spatiotemporal Heart Data

    NASA Astrophysics Data System (ADS)

    Simonotto, Jennifer; Spano, Mark; Ditto, William; Kavanagh, Katherine; Harrison, Robert G.

    2002-03-01

    Studying the nonlinear dynamics of ventricular fibrillation (VF) and ventricular tachycardia (VT) is necessary for the development of better models of and treatments for VF/VT. Through the use of voltage sensitive dyes and new high speed video cameras, we can now obtain optical mapping data that exhibit signal to noise ratios high enough to tackle (in 2D) the acquisition and analysis of spatiotemporal dynamics of VF/VT. It is now possible to effectively apply conventional statistical analyses (spatial correlation, coherence, signal decomposition), as well as techniques based upon wavefront motion (phase maps, propagation velocity vectors, waveform dynamics) of the electrical waves under study. Yet it is unclear if these measures alone will suffice to describe the complexity of the system. Thus we combine statistical and optical analysis with nonlinear analysis (entropy measures, symbolic dynamics, unstable periodic orbits (UPO) statistics) in order to extract the most information of the spatiotemporal behavior of VF/VT.

  17. A rare case of recurring calcifying epithelial odontogenic cyst in the maxillary sinus: a case report and literature review.

    PubMed

    Karun, Vinayak; Mishra, Amit Kumar; Saikhedkar, Rashmi

    2013-01-01

    Calcifying epithelial odontogenic cyst (CEOC) is an odontogenic cyst with epithelial lining. CEOC is a rare entity that occurs in a wide age range, does not show any gender predilection, and accounts for only 1% of all jaw cysts. The lesion generally occurs in the region anterior to maxillary and mandibular molars and either intraosseously or extraosseusly. This entity might present as a cystic or solid lesion. Enucleation is the recommended treatment for a simple, unicystic CEOC. A case of recurring CEOC in the right maxilla antrum is presented here. The patient presented to the authors after postsurgical recurrence. The case was evaluated thoroughly, and the cyst was resolved.

  18. Microscale spatiotemporal dynamics during neocortical propagation of human focal seizures.

    PubMed

    Wagner, Fabien B; Eskandar, Emad N; Cosgrove, G Rees; Madsen, Joseph R; Blum, Andrew S; Potter, N Stevenson; Hochberg, Leigh R; Cash, Sydney S; Truccolo, Wilson

    2015-11-15

    Some of the most clinically consequential aspects of focal epilepsy, e.g. loss of consciousness, arise from the generalization or propagation of seizures through local and large-scale neocortical networks. Yet, the dynamics of such neocortical propagation remain poorly understood. Here, we studied the microdynamics of focal seizure propagation in neocortical patches (4×4 mm) recorded via high-density microelectrode arrays (MEAs) implanted in people with pharmacologically resistant epilepsy. Our main findings are threefold: (1) a newly developed stage segmentation method, applied to local field potentials (LFPs) and multiunit activity (MUA), revealed a succession of discrete seizure stages, each lasting several seconds. These different stages showed characteristic evolutions in overall activity and spatial patterns, which were relatively consistent across seizures within each of the 5 patients studied. Interestingly, segmented seizure stages based on LFPs or MUA showed a dissociation of their spatiotemporal dynamics, likely reflecting different contributions of non-local synaptic inputs and local network activity. (2) As previously reported, some of the seizures showed a peak in MUA that happened several seconds after local seizure onset and slowly propagated across the MEA. However, other seizures had a more complex structure characterized by, for example, several MUA peaks, more consistent with the succession of discrete stages than the slow propagation of a simple wavefront of increased MUA. In both cases, nevertheless, seizures characterized by spike-wave discharges (SWDs, ~2-3 Hz) eventually evolved into patterns of phase-locked MUA and LFPs. (3) Individual SWDs or gamma oscillation cycles (25-60 Hz), characteristic of two different types of recorded seizures, tended to propagate with varying degrees of directionality, directions of propagation and speeds, depending on the identified seizure stage. However, no clear relationship was observed between the MUA

  19. Microscale Spatiotemporal Dynamics during Neocortical Propagation of Human Focal Seizures

    PubMed Central

    Wagner, Fabien B.; Eskandar, Emad N.; Cosgrove, G. Rees; Madsen, Joseph R.; Blum, Andrew S.; Potter, N. Stevenson; Hochberg, Leigh R.; Cash, Sydney S.; Truccolo, Wilson

    2015-01-01

    Some of the most clinically consequential aspects of focal epilepsy, e.g. loss of consciousness, arise from the generalization or propagation of seizures through local and large-scale neocortical networks. Yet, the dynamics of such neocortical propagation remain poorly understood. Here, we studied the microdynamics of focal seizure propagation in neocortical patches (4 × 4 mm) recorded via high-density microelectrode arrays (MEAs) implanted in people with pharmacologically resistant epilepsy. Our main findings are threefold: (1) A newly developed stage segmentation method, applied to local field potentials (LFPs) and multi-unit activity (MUA), revealed a succession of discrete seizure stages, each lasting several seconds. These different stages showed characteristic evolutions in overall activity and spatial patterns, which were relatively consistent across seizures within each of the 5 patients studied. Interestingly, segmented seizure stages based on LFPs or MUA showed a dissociation of their spatiotemporal dynamics, likely reflecting different contributions of non-local synaptic inputs and local network activity. (2) As previously reported, some of the seizures showed a peak in MUA that happened several seconds after local seizure onset and slowly propagated across the MEA. However, other seizures had a more complex structure characterized by, for example, several MUA peaks, more consistent with the succession of discrete stages than the slow propagation of a simple wavefront of increased MUA. In both cases, nevertheless, seizures characterized by spike-wave discharges (SWDs, ~ 2–3Hz) eventually evolved into patterns of phase-locked MUA and LFPs. (3) Individual SWDs or gamma oscillation cycles (25–60 Hz), characteristic of two different types of recorded seizures, tended to propagate with varying degrees of directionality, directions of propagation and speeds, depending on the identified seizure stage. However, no clear relationship was observed between the

  20. Toward Full Spatiotemporal Control on the Nanoscale

    NASA Astrophysics Data System (ADS)

    Durach, Maxim; Rusina, Anastasia; Stockman, Mark I.; Nelson, Keith

    2007-10-01

    We introduce an approach to implement full coherent control on nanometer length scales. It is based on spatio-temporal modulation of the surface plasmon polariton (SPP) fields at the thick edge of a nanowedge. The SPP wavepackets propagating toward the sharp edge of this nanowedge are compressed and adiabatically concentrated at a nanofocus, forming an ultrashort pulse of local fields. The one-dimensional spatial profile and temporal waveform of this pulse are completely coherently controlled.

  1. Toward full spatiotemporal control on the nanoscale.

    PubMed

    Durach, Maxim; Rusina, Anastasia; Stockman, Mark I; Nelson, Keith

    2007-10-01

    We introduce an approach to implement full coherent control on nanometer length scales. It is based on spatiotemporal modulation of the surface plasmon polariton (SPP) fields at the thick edge of a nanowedge. The SPP wavepackets propagating toward the sharp edge of this nanowedge are compressed and adiabatically concentrated at a nanofocus, forming an ultrashort pulse of local fields. The profile of the focused waveform as a function of time and one spatial dimension is completely coherently controlled.

  2. Spatiotemporal Patterns and Predictability of Cyberattacks

    PubMed Central

    Chen, Yu-Zhong; Huang, Zi-Gang; Xu, Shouhuai; Lai, Ying-Cheng

    2015-01-01

    A relatively unexplored issue in cybersecurity science and engineering is whether there exist intrinsic patterns of cyberattacks. Conventional wisdom favors absence of such patterns due to the overwhelming complexity of the modern cyberspace. Surprisingly, through a detailed analysis of an extensive data set that records the time-dependent frequencies of attacks over a relatively wide range of consecutive IP addresses, we successfully uncover intrinsic spatiotemporal patterns underlying cyberattacks, where the term “spatio” refers to the IP address space. In particular, we focus on analyzing macroscopic properties of the attack traffic flows and identify two main patterns with distinct spatiotemporal characteristics: deterministic and stochastic. Strikingly, there are very few sets of major attackers committing almost all the attacks, since their attack “fingerprints” and target selection scheme can be unequivocally identified according to the very limited number of unique spatiotemporal characteristics, each of which only exists on a consecutive IP region and differs significantly from the others. We utilize a number of quantitative measures, including the flux-fluctuation law, the Markov state transition probability matrix, and predictability measures, to characterize the attack patterns in a comprehensive manner. A general finding is that the attack patterns possess high degrees of predictability, potentially paving the way to anticipating and, consequently, mitigating or even preventing large-scale cyberattacks using macroscopic approaches. PMID:25992837

  3. Spatiotemporal Analysis of Differential Akt Regulation in Plasma Membrane Microdomains

    PubMed Central

    Gao, Xinxin

    2008-01-01

    As a central kinase in the phosphatidylinositol 3-kinase pathway, Akt has been the subject of extensive research; yet, spatiotemporal regulation of Akt in different membrane microdomains remains largely unknown. To examine dynamic Akt activity in membrane microdomains in living cells, we developed a specific and sensitive fluorescence resonance energy transfer-based Akt activity reporter, AktAR, through systematic testing of different substrates and fluorescent proteins. Targeted AktAR reported higher Akt activity with faster activation kinetics within lipid rafts compared with nonraft regions of plasma membrane. Disruption of rafts attenuated platelet-derived growth factor (PDGF)-stimulated Akt activity in rafts without affecting that in nonraft regions. However, in insulin-like growth factor-1 (IGF)-1 stimulation, Akt signaling in nonraft regions is dependent on that in raft regions. As a result, cholesterol depletion diminishes Akt activity in both regions. Thus, Akt activities are differentially regulated in different membrane microdomains, and the overall activity of this oncogenic pathway is dependent on raft function. Given the increased abundance of lipid rafts in some cancer cells, the distinct Akt-activating characteristics of PDGF and IGF-1, in terms of both effectiveness and raft dependence, demonstrate the capabilities of different growth factor signaling pathways to transduce differential oncogenic signals across plasma membrane. PMID:18701703

  4. Low dose reirradiation in combination with hyperthermia: a palliative treatment for patients with breast cancer recurring in previously irradiated areas.

    PubMed

    van der Zee, J; Treurniet-Donker, A D; The, S K; Helle, P A; Seldenrath, J J; Meerwaldt, J H; Wijnmaalen, A J; van den Berg, A P; van Rhoon, G C; Broekmeyer-Reurink, M P

    1988-12-01

    Ninety-seven patients with breast cancer recurring in a previously irradiated area (mean dose 44 Gy) were reirradiated in combination with hyperthermia and had evaluable tumor responses. In the reirradiation series, radiotherapy was given twice weekly in most patients, with a fraction size varying from 200 to 400 cGy, the total dose varying from 8 to 32 Gy. Hyperthermia was given following the radiotherapy fractions. The combined treatment resulted in 35% complete and 55% partial responses. Duration of response was median 4 months for partial response and 26 months for complete response, respectively. The median survival time for all patients was 12 months. Acute skin reaction was mild, with more than moderate erythema in only 14/97 patients. Thermal burns occurred in 44/97 patients, generally at sites where pain sensation was decreased, and therefore they did not cause much inconvenience. In the 19 patients who survived more than 2 years, no late radiation damage was observed. When patients who received a "high dose" (greater than 29 Gy and hyperthermia) were compared with those who received a "low dose" (less than 29 Gy and hyperthermia), a higher complete response rate was observed in the high dose group (58% vs. 24%), whereas no difference in acute toxicity was found. We conclude that reirradiation with 8 x 4 Gy in combination with hyperthermia twice weekly is a safe, effective and well tolerated method for palliative treatment of patients with breast cancer recurring in previously irradiated areas.

  5. Language Lateralization Represented by Spatiotemporal Mapping of Magnetoencephalography

    PubMed Central

    Tanaka, N.; Liu, H.; Reinsberger, C.; Madsen, J.R.; Bourgeois, B.F.; Dworetzky, B.A.; Hämäläinen, M.S.; Stufflebeam, S.M.

    2013-01-01

    BACKGROUND AND PURPOSE Determination of hemispheric language dominance is critical for planning epilepsy surgery. We assess the usefulness of spatiotemporal source analysis of magnetoencephalography for determining language laterality. MATERIALS AND METHODS Thirty-five patients with epilepsy were studied. The patients performed a semantic word-processing task during MEG recording. Epochs containing language-related neuromagnetic activity were averaged after preprocessing. The averaged data between 250 and 550 ms after stimulus were analyzed by using dynamic statistical parametric mapping. ROIs were obtained in the opercular and triangular parts of the inferior frontal gyrus, superior temporal gyrus, and supramarginal gyrus in both hemispheres. We calculated laterality indices according to 1) dSPM-amplitude method, based on the amplitude of activation in the ROIs, and 2) dSPM-counting method, based on the number of unit dipoles with activation over a threshold in the ROIs. The threshold was determined as half of the maximum value in all ROIs for each patient. A LI ≥0.10 or ≤−0.10 was considered left- or right-hemisphere dominance, respectively; a LI between −0.10 and 0.10 was considered bilateral. All patients underwent an intracarotid amobarbital procedure as part of presurgical evaluation. RESULTS The dSPM-counting method demonstrated laterality consistent with the IAP in 32 of 35 patients (91.4%), the remaining 3 (8.6%) demonstrated bilateral language representation, whereas the dSPM-amplitude method showed 18 (51.4%) concordant and 17 (48.6%) bilateral. No laterality opposite to the IAP was found. CONCLUSIONS Spatiotemporal mapping of language lateralization with the dSPM-counting method may reduce the necessity for an IAP in as many as 90% of patients. PMID:22878013

  6. The TPM3-NTRK1 rearrangement is a recurring event in colorectal carcinoma and is associated with tumor sensitivity to TRKA kinase inhibition.

    PubMed

    Ardini, Elena; Bosotti, Roberta; Borgia, Andrea Lombardi; De Ponti, Cristina; Somaschini, Alessio; Cammarota, Rosaria; Amboldi, Nadia; Raddrizzani, Laura; Milani, Andrea; Magnaghi, Paola; Ballinari, Dario; Casero, Daniele; Gasparri, Fabio; Banfi, Patrizia; Avanzi, Nilla; Saccardo, Maria B; Alzani, Rachele; Bandiera, Tiziano; Felder, Eduard; Donati, Daniele; Pesenti, Enrico; Sartore-Bianchi, Andrea; Gambacorta, Marcello; Pierotti, Marco A; Siena, Salvatore; Veronese, Silvio; Galvani, Arturo; Isacchi, Antonella

    2014-12-01

    The NTRK1 gene encodes Tropomyosin-related kinase A (TRKA), the high-affinity Nerve Growth Factor Receptor. NTRK1 was originally isolated from a colorectal carcinoma (CRC) sample as component of a somatic rearrangement (TPM3-NTRK1) resulting in expression of the oncogenic chimeric protein TPM3-TRKA, but there has been no subsequent report regarding the relevance of this oncogene in CRC. The KM12 human CRC cell line expresses the chimeric TPM3-TRKA protein and is hypersensitive to TRKA kinase inhibition. We report the detailed characterization of the TPM3-NTRK1 genomic rearrangement in KM12 cells and through a cellular screening approach, the identification of NMS-P626, a novel highly potent and selective TRKA inhibitor. NMS-P626 suppressed TPM3-TRKA phosphorylation and downstream signaling in KM12 cells and showed remarkable antitumor activity in mice bearing KM12 tumors. Finally, using quantitative reverse transcriptase PCR and immunohistochemistry (IHC) we identified the TPM3-NTRK1 rearrangement in a CRC clinical sample, therefore suggesting that this chromosomal translocation is indeed a low frequency recurring event in CRC and that such patients might benefit from therapy with TRKA kinase inhibitors.

  7. A Hierarchical Bayesian Approach for Learning Sparse Spatio-Temporal Decomposition of Multichannel EEG

    PubMed Central

    Wu, Wei; Chen, Zhe; Gao, Shangkai; Brown, Emery N.

    2011-01-01

    Multichannel electroencephalography (EEG) offers a non-invasive tool to explore spatio-temporal dynamics of brain activity. With EEG recordings consisting of multiple trials, traditional signal processing approaches that ignore inter-trial variability in the data may fail to accurately estimate the underlying spatio-temporal brain patterns. Moreover, precise characterization of such inter-trial variability per se can be of high scientific value in establishing the relationship between brain activity and behavior. In this paper, a statistical modeling framework is introduced for learning spatiotemporal decomposition of multiple-trial EEG data recorded under two contrasting experimental conditions. By modeling the variance of source signals as random variables varying across trials, the proposed two-stage hierarchical Bayesian model is able to capture inter-trial amplitude variability in the data in a sparse way where a parsimonious representation of the data can be obtained. A variational Bayesian (VB) algorithm is developed for statistical inference of the hierarchical model. The efficacy of the proposed modeling framework is validated with the analysis of both synthetic and real EEG data. In the simulation study we show that even at low signal-to-noise ratios our approach is able to recover with high precision the underlying spatiotemporal patterns and the evolution of source amplitude across trials; on two brain-computer interface (BCI) data sets we show that our VB algorithm can extract physiologically meaningful spatio-temporal patterns and make more accurate predictions than other two widely used algorithms: the common spatial patterns (CSP) algorithm and the Infomax algorithm for independent component analysis (ICA). The results demonstrate that our statistical modeling framework can serve as a powerful tool for extracting brain patterns, characterizing trial-to-trial brain dynamics, and decoding brain states by exploiting useful structures in the data. PMID

  8. On Configuration Trajectory Formation in Spatiotemporal Profile for Reproducing Human Hand Reaching Movement.

    PubMed

    Chen, Wenbin; Xiong, Caihua; Yue, Shigang

    2016-03-01

    Most functional reaching activities in daily living generally require a hand to reach the functional position in appropriate orientation with invariant spatiotemporal profile. Effectively reproducing such spatiotemporal feature of hand configuration trajectory in real time is essential to understand the human motor control and plan human-like motion on anthropomorphic robotic arm. However, there are no novel computational models in literature toward reproducing hand configuration-to-configuration movement in spatiotemporal profile. In response to the problem, this paper presents a computational framework for hand configuration trajectory formation based on hierarchical principle of human motor control. The composite potential field is constructed on special Euclidean Group to induce time-varying configuration toward target. The dynamic behavior of hand is described by a second-order kinematic model to produce the external representation of high-level motor control. The multivariate regression relation between intrinsic and extrinsic coordinates of arm, is statistically analyzed for determining the arm orientation in real time, which produces the external representation of low-level motor control. The proposed method is demonstrated in an anthropomorphic arm by performing several highly curved self-reaching movements. The generated configuration trajectories are compared with actual human movement in spatiotemporal profile to validate the proposed method.

  9. Enzyme-Responsive Delivery of Multiple Proteins with Spatiotemporal Control

    PubMed Central

    Zhu, Suwei; Nih, Lina; Carmichael, S. Thomas; Lu, Yunfeng; Segura, Tatiana

    2015-01-01

    The growth of tissues and organs is regulated by orchestrated signals from biomolecules such as enzymes and growth factors. The ability to deliver signal molecules in response to particular biological events (e.g., enzyme expression and activation) holds great promise towards tissue healing and regeneration. The current delivery vehicles mainly rely on hydrolysable scaffolds and thin films of protein-containing polymers, which cannot be programmed to respond to biological signals. We report herein an injectable delivery platform based on enantiomeric protein nanocapsules, which can deliver multiple proteins with spatiotemporal control in response to the tissue proteases secreted during wound healing. Exemplified by stroke and diabetic wound healing in mice, sequential delivery of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) greatly enhances tissue revascularization and vessel maturation, providing effective delivery vehicles for tissue engineering and reparative medicine. PMID:25962336

  10. Spatio-temporal evolution of the Choisille River (southern Parisian Basin, France) during the Weichselian and the Holocene as a record of climate trend and human activity in north-western Europe

    NASA Astrophysics Data System (ADS)

    Morin, Eymeric; Macaire, Jean-Jacques; Hinschberger, Florent; Gay-Ovéjéro, Isabelle; Rodrigues, Stéphane; Bakyono, Jean-Paul; Visset, Lionel

    2011-02-01

    The morpho-sedimentary evolution of the Choisille floodplain (lowland river, catchment: 288 km 2), a tributary of the River Loire in the south-western Parisian Basin, was studied through 61 core drillings along eight transects and a geophysical survey located in four stretches of the river: stretches A and B correspond to two sub-catchments, and stretches C and D are in the main valley. Sixty 14C and four OSL datings were obtained, and sediments were analysed on seven reference cores. Eight phases of evolution differing markedly from the evolution of more northern areas in the Parisian Basin and north-western Europe were identified from spatio-temporal distribution of nine lithological facies. The deepest incision phase (1) occurred during the first part of the Weichselian, followed by the deposition of a gravelly-sandy unit (phase 2) during the Middle Pleniglacial, which was deeply incised (phase 3), probably during the Bölling. From the Allerød up to the last third of the Boreal (phase 4), sedimentation was continuously dominated by peaty deposits, with no evidence of either increased hydraulic energy during the Younger Dryas, or of incision during the LateGlacial-Holocene transition. This trend seems to reflect the specificity of the south-western Parisian Basin climate from the Late Weichselian up to the end of the Boreal, due to the influence of the Atlantic Ocean, compared to more northern areas where the climate was more continental. The downstream incision trend during the last third of the Boreal up to the Subatlantic (phases 5 and 6) indicates a sharp increase in precipitation and vegetation cover; the lack of peaty sediments, widespread in north-western Europe, and also of precipitated carbonates frequent in the Parisian Basin, seems to be due to local physiographic characteristics. The main part of the sediment filling, which is principally silty and retrograde, began during the Subatlantic (phase 7 and 8) as a result of deforestation of the plateaux

  11. High-Fidelity Reproduction of Spatiotemporal Visual Signals for Retinal Prosthesis

    PubMed Central

    Jepson, Lauren H.; Hottowy, Pawel; Weiner, Geoffrey A.; Dabrowski, Władys1aw; Litke, Alan M.; Chichilnisky, E.J.

    2015-01-01

    SUMMARY Natural vision relies on spatiotemporal patterns of electrical activity in the retina. We investigated the feasibility of veridically reproducing such patterns with epiretinal prostheses. Multielectrode recordings and visual and electrical stimulation were performed on populations of identified ganglion cells in isolated peripheral primate retina. Electrical stimulation patterns were designed to reproduce recorded waves of activity elicited by a moving visual stimulus. Electrical responses in populations of ON parasol cells exhibited high spatial and temporal precision, matching or exceeding the precision of visual responses measured in the same cells. Computational readout of electrical and visual responses produced similar estimates of stimulus speed, confirming the fidelity of electrical stimulation for biologically relevant visual signals. These results suggest the possibility of producing rich spatiotemporal patterns of retinal activity with a prosthesis and that temporal multiplexing may aid in reproducing the neural code of the retina. PMID:24910077

  12. Spatiotemporal Features of Retinal Waves Instruct the Wiring of the Visual Circuitry

    PubMed Central

    Arroyo, David A.; Feller, Marla B.

    2016-01-01

    Coordinated spontaneous activity is present in different sensory systems during early stages of development. This activity is thought to play a critical role in the development of sensory representations before the maturation of sensory experience. In the visual system, the mechanisms by which spatiotemporal properties of retinal spontaneous activity, called retinal waves, drive developmental events has been well studied. Recent advancements in pharmacological, genetic, and optogenetic manipulations have provided further understanding of the contribution of specific spatiotemporal properties of retinal waves to eye-specific segregation and retinotopic refinement of retinofugal projections. Here we review some of the recent progress in understanding the role of retinal waves in the early stages of visual system development, prior to the maturation of vision. PMID:27507937

  13. Spatiotemporal Features of Retinal Waves Instruct the Wiring of the Visual Circuitry.

    PubMed

    Arroyo, David A; Feller, Marla B

    2016-01-01

    Coordinated spontaneous activity is present in different sensory systems during early stages of development. This activity is thought to play a critical role in the development of sensory representations before the maturation of sensory experience. In the visual system, the mechanisms by which spatiotemporal properties of retinal spontaneous activity, called retinal waves, drive developmental events has been well studied. Recent advancements in pharmacological, genetic, and optogenetic manipulations have provided further understanding of the contribution of specific spatiotemporal properties of retinal waves to eye-specific segregation and retinotopic refinement of retinofugal projections. Here we review some of the recent progress in understanding the role of retinal waves in the early stages of visual system development, prior to the maturation of vision.

  14. Transition effects characterization on spatiotemporal images

    NASA Astrophysics Data System (ADS)

    Ruiloba, Rosa I.; Joly, Philippe

    2000-10-01

    This article presents the results of a study on spatio-temporal images to evaluate their performances for video-to-shots segmentation purposes. Some shots segmentation methods involve spatio-temporal images that are computed by a projection of successive video frames over the X or Y-axis. On these projections, transition effects and motion are supposed to have different characteristics. Whereas cuts can be easily recognized, the main problem remains in determining a measure that discriminates motions from gradual transition effects. In this article, the quality of transition detections based on line similarity of spatio-temporal images is studied. The probability functions of several measures are estimated to determine which one produce the lowest detection error rate. These distributions are computed on four classes of events: intra shot sequences without motion, sequences with cuts, sequences with fades and sequences with motion. A line matching is performed, based on correlation estimations between projection lines. To separate these classes, we estimate first the density probability functions of the correlation between consecutive lines for each class. For different line segment sizes, the experimental results prove that the class separation can not be clearly produced. To take into account the evolution of the correlation and because we try to detect some particular types of boundaries, we then consider ratios between statistic moments. There are computed over a subset of correlation values. The results show that used measures, based on the matching of projection lines, can not discriminate between motion and fade. Only a subset of motions will be differentiated from gradual transitions. Therefore previous measures should be combined with methods that produce complementary results. Such a method could be a similar measure based on correlation between spatial-shifted segments.

  15. Spatial and Spatiotemporal Data Mining: Recent Advances

    SciTech Connect

    Shekhar, Shashi; Vatsavai, Raju; Celik, Mete

    2008-01-01

    Explosive growth in geospatial data and the emergence of new spatial technologies emphasize the need for automated discovery of spatial knowledge. Spatial data mining is the process of discovering interesting and previously unknown, but potentially useful patterns from large spatial databases. The complexity of spatial data and intrinsic spatial relationships limits the usefulness of conventional data mining techniques for extracting spatial patterns. In this chapter we explore the emerging field of spatial data mining, focusing on four major topics: prediction and classification, outlier detection, co-location mining, and clustering. Spatiotemporal data mining is also briefly discussed.

  16. Spatiotemporal evolution of bacterial biofilm colonies

    NASA Astrophysics Data System (ADS)

    Wilking, James; Koehler, Stephan; Sinha, Naveen; Seminara, Agnese; Brenner, Michael; Weitz, David

    2014-03-01

    Many bacteria on earth live in surface-attached communities known as biofilms. Gene expression in a biofilm is typically varied, resulting in a variety of phenotypes within a single film. These phenotypes play a critical role in biofilm physiology and development. We use time-resolved, wide-field fluorescence microscopy to image triple-labeled fluorescent Bacillus Subtilis colonies grown on agar to determine in a non-invasive fashion the evolving phenotypes. We infer their transition rates from the resulting spatiotemporal maps of gene expression. Moreover, we correlate these transition rates with local measurements of nutrient concentration to determine the influence of extracellular signals on gene expression.

  17. Spatiotemporal rogue events in femtosecond filamentation

    SciTech Connect

    Majus, D.; Jukna, V.; Valiulis, G.; Dubietis, A.; Faccio, D.

    2011-02-15

    We present experimental and numerical investigations of optical extreme (rogue) event statistics recorded in the regime of femtosecond pulse filamentation in water. In the spectral domain, the extreme events manifest themselves as either large or small extremes of the spectral intensity, justified by right- or left-tailed statistical distributions, respectively. In the time domain, the observed extreme events are associated with pulse splitting and energy redistribution in space and therefore are exquisitely linked to three-dimensional, spatiotemporal dynamics and formation of the X waves.

  18. The spatiotemporal MEG covariance matrix modeled as a sum of Kronecker products.

    PubMed

    Bijma, Fetsje; de Munck, Jan C; Heethaar, Rob M

    2005-08-15

    The single Kronecker product (KP) model for the spatiotemporal covariance of MEG residuals is extended to a sum of Kronecker products. This sum of KP is estimated such that it approximates the spatiotemporal sample covariance best in matrix norm. Contrary to the single KP, this extension allows for describing multiple, independent phenomena in the ongoing background activity. Whereas the single KP model can be interpreted by assuming that background activity is generated by randomly distributed dipoles with certain spatial and temporal characteristics, the sum model can be physiologically interpreted by assuming a composite of such processes. Taking enough terms into account, the spatiotemporal sample covariance matrix can be described exactly by this extended model. In the estimation of the sum of KP model, it appears that the sum of the first 2 KP describes between 67% and 93%. Moreover, these first two terms describe two physiological processes in the background activity: focal, frequency-specific alpha activity, and more widespread non-frequency-specific activity. Furthermore, temporal nonstationarities due to trial-to-trial variations are not clearly visible in the first two terms, and, hence, play only a minor role in the sample covariance matrix in terms of matrix power. Considering the dipole localization, the single KP model appears to describe around 80% of the noise and seems therefore adequate. The emphasis of further improvement of localization accuracy should be on improving the source model rather than the covariance model.

  19. Faecal microbiota transplantation for recurring Clostridium difficile infection in a patient with Crohn's disease and ileorectal anastomosis.

    PubMed

    Oppfeldt, Asser Mathiassen; Dahlerup, Jens F; Christensen, Lisbet A; Hvas, Christian L

    2016-09-23

    Faecal microbiota transplantation (FMT) is increasingly being used to treat refractory and recurring Clostridium difficile infection (CDI). Although FMT appears to be safe and highly effective in patients with a preserved colon and immunocompetence, its use in patients with inflammatory bowel disease (IBD) who are on immunomodulating therapies is controversial. In particular, patients who have undergone colectomy may have different treatment responses to FMT. In this case report, we describe the successful use of FMT in a female patient aged 19 years with Crohn's disease who underwent ileorectal anastomosis following colectomy. She had recurrent CDIs that were refractory to metronidazole, pulse-tapered vancomycin and fidaxomicin treatments. She underwent 2 FMTs, which were performed via sigmoidoscopy; her mother served as a donor. Follow-up was conducted for 12 months and indicated sustained remission of CDI.

  20. Recurring sequence-structure motifs in (βα)8-barrel proteins and experimental optimization of a chimeric protein designed based on such motifs.

    PubMed

    Wang, Jichao; Zhang, Tongchuan; Liu, Ruicun; Song, Meilin; Wang, Juncheng; Hong, Jiong; Chen, Quan; Liu, Haiyan

    2017-02-01

    An interesting way of generating novel artificial proteins is to combine sequence motifs from natural proteins, mimicking the evolutionary path suggested by natural proteins comprising recurring motifs. We analyzed the βα and αβ modules of TIM barrel proteins by structure alignment-based sequence clustering. A number of preferred motifs were identified. A chimeric TIM was designed by using recurring elements as mutually compatible interfaces. The foldability of the designed TIM protein was then significantly improved by six rounds of directed evolution. The melting temperature has been improved by more than 20°C. A variety of characteristics suggested that the resulting protein is well-folded. Our analysis provided a library of peptide motifs that is potentially useful for different protein engineering studies. The protein engineering strategy of using recurring motifs as interfaces to connect partial natural proteins may be applied to other protein folds.

  1. Asynchronous Visualization of Spatiotemporal Information for Multiple Moving Targets

    ERIC Educational Resources Information Center

    Wang, Huadong

    2013-01-01

    In the modern information age, the quantity and complexity of spatiotemporal data is increasing both rapidly and continuously. Sensor systems with multiple feeds that gather multidimensional spatiotemporal data will result in information clusters and overload, as well as a high cognitive load for users of these systems. To meet future…

  2. Faster P300 Classifier Training Using Spatiotemporal Beamforming.

    PubMed

    Wittevrongel, Benjamin; Van Hulle, Marc M

    2016-05-01

    The linearly-constrained minimum-variance (LCMV) beamformer is traditionally used as a spatial filter for source localization, but here we consider its spatiotemporal extension for P300 classification. We compare two variants and show that the spatiotemporal LCMV beamformer is at par with state-of-the-art P300 classifiers, but several orders of magnitude faster in training the classifier.

  3. Spatiotemporal-atlas-based dynamic speech imaging

    NASA Astrophysics Data System (ADS)

    Fu, Maojing; Woo, Jonghye; Liang, Zhi-Pei; Sutton, Bradley P.

    2016-03-01

    Dynamic magnetic resonance imaging (DS-MRI) has been recognized as a promising method for visualizing articulatory motion of speech in scientific research and clinical applications. However, characterization of the gestural and acoustical properties of the vocal tract remains a challenging task for DS-MRI because it requires: 1) reconstructing high-quality spatiotemporal images by incorporating stronger prior knowledge; and 2) quantitatively interpreting the reconstructed images that contain great motion variability. This work presents a novel imaging method that simultaneously meets both requirements by integrating a spatiotemporal atlas into a Partial Separability (PS) model-based imaging framework. Through the use of an atlas-driven sparsity constraint, this method is capable of capturing high-quality articulatory dynamics at an imaging speed of 102 frames per second and a spatial resolution of 2.2 × 2.2 mm2. Moreover, the proposed method enables quantitative characterization of variability of speech motion, compared to the generic motion pattern across all subjects, through the spatial residual components.

  4. Spatio-temporal clustering of wildfires in Portugal

    NASA Astrophysics Data System (ADS)

    Costa, R.; Pereira, M. G.; Caramelo, L.; Vega Orozco, C.; Kanevski, M.

    2012-04-01

    Several studies have shown that wildfires in Portugal presenthigh temporal as well as high spatial variability (Pereira et al., 2005, 2011). The identification and characterization of spatio-temporal clusters contributes to a comprehensivecharacterization of the fire regime and to improve the efficiency of fire prevention and combat activities. The main goalsin this studyare: (i) to detect the spatio-temporal clusters of burned area; and, (ii) to characterize these clusters along with the role of human and environmental factors. The data were supplied by the National Forest Authority(AFN, 2011) and comprises: (a)the Portuguese Rural Fire Database, PRFD, (Pereira et al., 2011) for the 1980-2007period; and, (b) the national mapping burned areas between 1990 and 2009. In this work, in order to complement the more common cluster analysis algorithms, an alternative approach based onscan statistics and on the permutation modelwas used. This statistical methodallows the detection of local excess events and to test if such an excess can reasonably have occurred by chance.Results obtained for different simulations performed for different spatial and temporal windows are presented, compared and interpreted.The influence of several fire factors such as (climate, vegetation type, etc.) is also assessed. Pereira, M.G., Trigo, R.M., DaCamara, C.C., Pereira, J.M.C., Leite, S.M., 2005:"Synoptic patterns associated with large summer forest fires in Portugal".Agricultural and Forest Meteorology. 129, 11-25. Pereira, M. G., Malamud, B. D., Trigo, R. M., and Alves, P. I.: The history and characteristics of the 1980-2005 Portuguese rural fire database, Nat. Hazards Earth Syst. Sci., 11, 3343-3358, doi:10.5194/nhess-11-3343-2011, 2011 AFN, 2011: AutoridadeFlorestalNacional (National Forest Authority). Available at http://www.afn.min-agricultura.pt/portal.

  5. Transient spatiotemporal chaos in the Morris-Lecar neuronal ring network

    NASA Astrophysics Data System (ADS)

    Keplinger, Keegan; Wackerbauer, Renate

    2014-03-01

    Transient behavior is thought to play an integral role in brain functionality. Numerical simulations of the firing activity of diffusively coupled, excitable Morris-Lecar neurons reveal transient spatiotemporal chaos in the parameter regime below the saddle-node on invariant circle bifurcation point. The neighborhood of the chaotic saddle is reached through perturbations of the rest state, in which few initially active neurons at an effective spatial distance can initiate spatiotemporal chaos. The system escapes from the neighborhood of the chaotic saddle to either the rest state or to a state of pulse propagation. The lifetime of the chaotic transients is manipulated in a statistical sense through a singular application of a synchronous perturbation to a group of neurons.

  6. Spatiotemporal neuromodulation therapies engaging muscle synergies improve motor control after spinal cord injury

    PubMed Central

    Wenger, Nikolaus; Moraud, Eduardo Martin; Gandar, Jerome; Musienko, Pavel; Capogrosso, Marco; Baud, Laetitia; Le Goff, Camille G.; Barraud, Quentin; Pavlova, Natalia; Dominici, Nadia; Minev, Ivan R.; Asboth, Leonie; Hirsch, Arthur; Duis, Simone; Kreider, Julie; Mortera, Andrea; Haverbeck, Oliver; Kraus, Silvio; Schmitz, Felix; DiGiovanna, Jack; van den Brand, Rubia; Bloch, Jocelyne; Detemple, Peter; Lacour, Stéphanie P.; Bézard, Erwan; Micera, Silvestro; Courtine, Grégoire

    2016-01-01

    Electrical neuromodulation of lumbar segments improves motor control after spinal cord injury in animal models and humans. However, the physiological principles underlying the effect of this intervention remain poorly understood, which has limited this therapeutic approach to continuous stimulation applied to restricted spinal cord locations. Here, we developed novel stimulation protocols that reproduce the natural dynamics of motoneuron activation during locomotion. For this, we computed the spatiotemporal activation pattern of muscle synergies during locomotion in healthy rats. Computer simulations identified optimal electrode locations to target each synergy through the recruitment of proprioceptive feedback circuits. This framework steered the design of spatially selective spinal implants and real–time control software that modulate extensor versus flexor synergies with precise temporal resolution. Spatiotemporal neuromodulation therapies improved gait quality, weight–bearing capacities, endurance and skilled locomotion in multiple rodent models of spinal cord injury. These new concepts are directly translatable to strategies to improve motor control in humans. PMID:26779815

  7. Transient spatiotemporal chaos in the Morris-Lecar neuronal ring network

    SciTech Connect

    Keplinger, Keegan Wackerbauer, Renate

    2014-03-15

    Transient behavior is thought to play an integral role in brain functionality. Numerical simulations of the firing activity of diffusively coupled, excitable Morris-Lecar neurons reveal transient spatiotemporal chaos in the parameter regime below the saddle-node on invariant circle bifurcation point. The neighborhood of the chaotic saddle is reached through perturbations of the rest state, in which few initially active neurons at an effective spatial distance can initiate spatiotemporal chaos. The system escapes from the neighborhood of the chaotic saddle to either the rest state or to a state of pulse propagation. The lifetime of the chaotic transients is manipulated in a statistical sense through a singular application of a synchronous perturbation to a group of neurons.

  8. 77 FR 39174 - Safety Zone, Temporary Change for Recurring Fifth Coast Guard District Fireworks Displays...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-02

    ... Display. This action is intended to restrict vessel traffic movement to protect mariners from the hazards... implications for federalism. 6. Protest Activities The Coast Guard respects the First Amendment rights of... Order 12630, Governmental Actions and Interference With Constitutionally Protected Property Rights....

  9. Microbial communities acclimate to recurring changes in soil redox potential status

    SciTech Connect

    DeAngelis, Kristen M.; Silver, Whendee; Thompson, Andrew; Firestone, Mary K.

    2010-12-03

    Rapidly fluctuating environmental conditions can significantly stress organisms, particularly when fluctuations cross thresholds of normal physiological tolerance. Redox potential fluctuations are common in humid tropical soils, and microbial community acclimation or avoidance strategies for survival will in turn shape microbial community diversity and biogeochemistry. To assess the extent to which indigenous bacterial and archaeal communities are adapted to changing in redox potential, soils were incubated under static anoxic, static oxic or fluctuating redox potential conditions, and the standing (DNA-based) and active (RNA-based) communities and biogeochemistry were determined. Fluctuating redox potential conditions permitted simultaneous CO{sub 2} respiration, methanogenesis, N{sub 2}O production and iron reduction. Exposure to static anaerobic conditions significantly changed community composition, while 4-day redox potential fluctuations did not. Using RNA: DNA ratios as a measure of activity, 285 taxa were more active under fluctuating than static conditions, compared with three taxa that were more active under static compared with fluctuating conditions. These data suggest an indigenous microbialcommunity adapted to fluctuating redox potential.

  10. Spatiotemporal Patterns of Noise-Driven Confined Actin Waves in Living Cells

    NASA Astrophysics Data System (ADS)

    Bernitt, Erik; Döbereiner, Hans-Günther

    2017-01-01

    Cells utilize waves of polymerizing actin to reshape their morphologies, which is central to physiological and pathological processes alike. Here, we force dorsal actin waves to propagate on one-dimensional domains with periodic boundary conditions, which results in striking spatiotemporal patterns with a clear signature of noise-driven dynamics. We show that these patterns can be very closely reproduced with a noise-driven active medium at coherence resonance.

  11. Generation of spatiotemporally correlated spike trains and local field potentials using a multivariate autoregressive process.

    PubMed

    Gutnisky, Diego A; Josić, Kresimir

    2010-05-01

    Experimental advances allowing for the simultaneous recording of activity at multiple sites have significantly increased our understanding of the spatiotemporal patterns in neural activity. The impact of such patterns on neural coding is a fundamental question in neuroscience. The simulation of spike trains with predetermined activity patterns is therefore an important ingredient in the study of potential neural codes. Such artificially generated spike trains could also be used to manipulate cortical neurons in vitro and in vivo. Here, we propose a method to generate spike trains with given mean firing rates and cross-correlations. To capture this statistical structure we generate a point process by thresholding a stochastic process that is continuous in space and discrete in time. This stochastic process is obtained by filtering Gaussian noise through a multivariate autoregressive (AR) model. The parameters of the AR model are obtained by a nonlinear transformation of the point-process correlations to the continuous-process correlations. The proposed method is very efficient and allows for the simulation of large neural populations. It can be optimized to the structure of spatiotemporal correlations and generalized to nonstationary processes and spatiotemporal patterns of local field potentials and spike trains.

  12. Spatio-temporal changes of photosynthesis in carnivorous plants in response to prey capture, retention and digestion.

    PubMed

    Pavlovič, Andrej

    2010-11-01

    Carnivorous plants have evolved modified leaves into the traps which assist in nutrient uptake from captured prey. It is known that the traps of carnivorous plants have usually lower photosynthetic rates than assimilation leaves as a result of adaptation to carnivory. However a few recent studies have indicated that photosynthesis and respiration undergo spatio-temporal changes during prey capture and retention, especially in the genera with active trapping mechanisms. This study describes the spatio-temporal changes of effective quantum yield of photochemical energy conversion in photosystem II (Ф PSII) in response to ant-derived formic acid during its capture and digestion.

  13. A Flexible Spatio-Temporal Model for Air Pollution with Spatial and Spatio-Temporal Covariates

    PubMed Central

    Lindström, Johan; Szpiro, Adam A; Sampson, Paul D; Oron, Assaf P; Richards, Mark; Larson, Tim V; Sheppard, Lianne

    2013-01-01

    The development of models that provide accurate spatio-temporal predictions of ambient air pollution at small spatial scales is of great importance for the assessment of potential health effects of air pollution. Here we present a spatio-temporal framework that predicts ambient air pollution by combining data from several different monitoring networks and deterministic air pollution model(s) with geographic information system (GIS) covariates. The model presented in this paper has been implemented in an R package, SpatioTemporal, available on CRAN. The model is used by the EPA funded Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air) to produce estimates of ambient air pollution; MESA Air uses the estimates to investigate the relationship between chronic exposure to air pollution and cardiovascular disease. In this paper we use the model to predict long-term average concentrations of NOx in the Los Angeles area during a ten year period. Predictions are based on measurements from the EPA Air Quality System, MESA Air specific monitoring, and output from a source dispersion model for traffic related air pollution (Caline3QHCR). Accuracy in predicting long-term average concentrations is evaluated using an elaborate cross-validation setup that accounts for a sparse spatio-temporal sampling pattern in the data, and adjusts for temporal effects. The predictive ability of the model is good with cross-validated R2 of approximately 0.7 at subject sites. Replacing four geographic covariate indicators of traffic density with the Caline3QHCR dispersion model output resulted in very similar prediction accuracy from a more parsimonious and more interpretable model. Adding traffic-related geographic covariates to the model that included Caline3QHCR did not further improve the prediction accuracy. PMID:25264424

  14. Spatiotemporal dynamics of counterpropagating Airy beams

    PubMed Central

    Wiersma, Noémi; Marsal, Nicolas; Sciamanna, Marc; Wolfersberger, Delphine

    2015-01-01

    We analyse theoretically the spatiotemporal dynamics of two incoherent counterpropagating Airy beams interacting in a photorefractive crystal under focusing conditions. For a large enough nonlinearity strength the interaction between the two Airy beams leads to light-induced waveguiding. The stability of the waveguide is determined by the crystal length, the nonlinearity strength and the beam’s intensities and is improved when comparing to the situation using Gaussian beams. We further identify the threshold above which the waveguide is no longer static but evolves dynamically either time-periodically or even chaotically. Above the stability threshold, each Airy-soliton moves erratically between privileged output positions that correspond to the spatial positions of the lobes of the counterpropagating Airy beam. These results suggest new ways of creating dynamically varying waveguides, optical logic gates and chaos-based computing. PMID:26315530

  15. Secure communication based on spatiotemporal chaos

    NASA Astrophysics Data System (ADS)

    Ren, Hai-Peng; Bai, Chao

    2015-08-01

    In this paper, we propose a novel approach to secure communication based on spatiotemporal chaos. At the transmitter end, the state variables of the coupled map lattice system are divided into two groups: one is used as the key to encrypt the plaintext in the N-shift encryption function, and the other is used to mix with the output of the N-shift function to further confuse the information to transmit. At the receiver end, the receiver lattices are driven by the received signal to synchronize with the transmitter lattices and an inverse procedure of the encoding is conducted to decode the information. Numerical simulation and experiment based on the TI TMS320C6713 Digital Signal Processor (DSP) show the feasibility and the validity of the proposed scheme. Project supported by the National Natural Science Foundation of China (Grant No. 61172070) and the Funds from the Science and Technology Innovation Team of Shaanxi Province, China (Grant No. 2013CKT-04).

  16. Cortical spatiotemporal dimensionality reduction for visual grouping.

    PubMed

    Cocci, Giacomo; Barbieri, Davide; Citti, Giovanna; Sarti, Alessandro

    2015-06-01

    The visual systems of many mammals, including humans, are able to integrate the geometric information of visual stimuli and perform cognitive tasks at the first stages of the cortical processing. This is thought to be the result of a combination of mechanisms, which include feature extraction at the single cell level and geometric processing by means of cell connectivity. We present a geometric model of such connectivities in the space of detected features associated with spatiotemporal visual stimuli and show how they can be used to obtain low-level object segmentation. The main idea is to define a spectral clustering procedure with anisotropic affinities over data sets consisting of embeddings of the visual stimuli into higher-dimensional spaces. Neural plausibility of the proposed arguments will be discussed.

  17. Concerning immune synapses: a spatiotemporal timeline

    PubMed Central

    Ortega-Carrion, Alvaro; Vicente-Manzanares, Miguel

    2016-01-01

    The term “immune synapse” was originally coined to highlight the similarities between the synaptic contacts between neurons in the central nervous system and the cognate, antigen-dependent interactions between T cells and antigen-presenting cells. Here, instead of offering a comprehensive molecular catalogue of molecules involved in the establishment, stabilization, function, and resolution of the immune synapse, we follow a spatiotemporal timeline that begins at the initiation of exploratory contacts between the T cell and the antigen-presenting cell and ends with the termination of the contact. We focus on specific aspects that distinguish synapses established by cytotoxic and T helper cells as well as unresolved issues and controversies regarding the formation of this intercellular structure. PMID:27092248

  18. Attention Modulates Spatio-temporal Grouping

    PubMed Central

    Aydın, Murat; Herzog, Michael H.; Öğmen, Haluk

    2011-01-01

    Dynamic stimuli are ubiquitous in natural viewing conditions implying that grouping operations need to operate, not only in space, but also jointly in space and time. Moreover, in natural viewing, attention plays an important role in controlling how resources are allocated. We investigated how attention interacts with spatiotemporal perceptual grouping by using a bistable stimulus, called the Ternus-Pikler display. Ternus-Pikler displays can give rise to two different motion percepts, called Element Motion (EM) and Group Motion (GM), the former dominating at short Inter-Stimulus Intervals (ISIs) and the latter at long ISIs. Our results indicate that GM grouping requires more attentional resources than EM grouping. Different theoretical accounts of perceptual grouping and attention are discussed and evaluated in the light of the current results. PMID:21266181

  19. Characterizing configurations of fire ignition points through spatiotemporal point processes

    NASA Astrophysics Data System (ADS)

    Comas, C.; Costafreda-Aumedes, S.; Vega-Garcia, C.

    2014-04-01

    Human-caused forest fires are usually regarded as unpredictable but often exhibit trends towards clustering in certain locations and periods. Characterizing such configurations is crucial for understanding spatiotemporal fire dynamics and implementing preventive actions. Our objectives were to analyse the spatiotemporal point configuration and to test for spatiotemporal interaction. We characterized the spatiotemporal structure of 984 fire ignition points in a study area of Galicia, Spain, during 2007-2011 by the K-Ripley's function. Our results suggest the presence of spatiotemporal structures for time lags of less than two years and ignition point distances in the range 0-12 km. Ignition centre points at time lags of less than 100 days are aggregated for any inter-event distance. This cluster structure loses strength as the time lag increases, and at time lags of more than 365 days this cluster structure is not significant for any lag distance. Our results also suggest spatiotemporal interdependencies at time lags of less than 100 days and inter-event distances of less than 10 km. At time lags of up to 365 days spatiotemporal components are independent for any point distance. These results suggest that risk conditions occur locally and are short-lived in this study area.

  20. Neural Sequence Generation Using Spatiotemporal Patterns of Inhibition

    PubMed Central

    Cannon, Jonathan; Kopell, Nancy; Gardner, Timothy; Markowitz, Jeffrey

    2015-01-01

    Stereotyped sequences of neural activity are thought to underlie reproducible behaviors and cognitive processes ranging from memory recall to arm movement. One of the most prominent theoretical models of neural sequence generation is the synfire chain, in which pulses of synchronized spiking activity propagate robustly along a chain of cells connected by highly redundant feedforward excitation. But recent experimental observations in the avian song production pathway during song generation have shown excitatory activity interacting strongly with the firing patterns of inhibitory neurons, suggesting a process of sequence generation more complex than feedforward excitation. Here we propose a model of sequence generation inspired by these observations in which a pulse travels along a spatially recurrent excitatory chain, passing repeatedly through zones of local feedback inhibition. In this model, synchrony and robust timing are maintained not through redundant excitatory connections, but rather through the interaction between the pulse and the spatiotemporal pattern of inhibition that it creates as it circulates the network. These results suggest that spatially and temporally structured inhibition may play a key role in sequence generation. PMID:26536029

  1. Spatiotemporal Dynamics of Cortical Representations during and after Stimulus Presentation

    PubMed Central

    van de Nieuwenhuijzen, Marieke E.; van den Borne, Eva W. P.; Jensen, Ole; van Gerven, Marcel A. J.

    2016-01-01

    Visual perception is a spatiotemporally complex process. In this study, we investigated cortical dynamics during and after stimulus presentation. We observed that visual category information related to the difference between faces and objects became apparent in the occipital lobe after 63 ms. Within the next 110 ms, activation spread out to include the temporal lobe before returning to residing mainly in the occipital lobe again. After stimulus offset, a peak in information was observed, comparable to the peak after stimulus onset. Moreover, similar processes, albeit not identical, seemed to underlie both peaks. Information about the categorical identity of the stimulus remained present until 677 ms after stimulus offset, during which period the stimulus had to be retained in working memory. Activation patterns initially resembled those observed during stimulus presentation. After about 200 ms, however, this representation changed and class-specific activity became more equally distributed over the four lobes. These results show that, although there are common processes underlying stimulus representation both during and after stimulus presentation, these representations change depending on the specific stage of perception and maintenance. PMID:27242453

  2. Statistical physics model for the spatiotemporal evolution of faults

    SciTech Connect

    Cowie, P.A.; Vanneste, C.; Sornette, D.

    1993-12-01

    A statistical physics model is used to simulate antiplane shear deformation and rupture of a tectonic plate with heterogeneous material properties. We document the spatiotemporal evolution of the rupture pattern in response to a constant velocity boundary condition. A fundamental feature of this model is that ruptures become strongly correlated in space and time, leading to the development of complex fractal structures. These structures, or `faults` are simply defined by the loci where deformation accumulates. Repeated rupture of a fault occurs in events (`earthquakes`) which themselves exhibit both spatial and temporal clustering. Furthermore, we observe that a fault may be active for long periods of time until the locus of activity spontaneously switches to a different fault. The characteristics of this scalar model suggest that spontaneous self-organization of active tectonics does not result solely from the tensorial nature of crustal deformation. Furthermore, the localization of the deformation is a dynamical effect rather than a consequence of preexisting structure or preferential weakening of faults compared to the surrounding medium. We present an analysis of scaling relationships exhibited by the fault pattern and the earthquakes in this model.

  3. Spatio-temporal properties of letter crowding

    PubMed Central

    Chung, Susana T. L.

    2016-01-01

    Crowding between adjacent letters has been investigated primarily as a spatial effect. The purpose of this study was to investigate the spatio-temporal properties of letter crowding. Specifically, we examined the systematic changes in the degradation effects in letter identification performance when adjacent letters were presented with a temporal asynchrony, as a function of letter separation and between the fovea and the periphery. We measured proportion-correct performance for identifying the middle target letter in strings of three lowercase letters at the fovea and 10° in the inferior visual field, for a range of center-to-center letter separations and a range of stimulus onset asynchronies (SOA) between the target and flanking letters (positive SOAs: target preceded flankers). As expected, the accuracy for identifying the target letters reduces with decreases in letter separation. This crowding effect shows a strong dependency on SOAs, such that crowding is maximal between 0 and ∼100 ms (depending on conditions) and diminishes for larger SOAs (positive or negative). Maximal crowding does not require the target and flanking letters to physically coexist for the entire presentation duration. Most importantly, crowding can be minimized even for closely spaced letters if there is a large temporal asynchrony between the target and flankers. The reliance of letter identification performance on SOAs and how it changes with letter separations imply that the crowding effect can be traded between space and time. Our findings are consistent with the notion that crowding should be considered as a spatio-temporal, and not simply a spatial, effect. PMID:27088895

  4. Spatio-temporal properties of letter crowding.

    PubMed

    Chung, Susana T L

    2016-01-01

    Crowding between adjacent letters has been investigated primarily as a spatial effect. The purpose of this study was to investigate the spatio-temporal properties of letter crowding. Specifically, we examined the systematic changes in the degradation effects in letter identification performance when adjacent letters were presented with a temporal asynchrony, as a function of letter separation and between the fovea and the periphery. We measured proportion-correct performance for identifying the middle target letter in strings of three lowercase letters at the fovea and 10° in the inferior visual field, for a range of center-to-center letter separations and a range of stimulus onset asynchronies (SOA) between the target and flanking letters (positive SOAs: target preceded flankers). As expected, the accuracy for identifying the target letters reduces with decreases in letter separation. This crowding effect shows a strong dependency on SOAs, such that crowding is maximal between 0 and ∼100 ms (depending on conditions) and diminishes for larger SOAs (positive or negative). Maximal crowding does not require the target and flanking letters to physically coexist for the entire presentation duration. Most importantly, crowding can be minimized even for closely spaced letters if there is a large temporal asynchrony between the target and flankers. The reliance of letter identification performance on SOAs and how it changes with letter separations imply that the crowding effect can be traded between space and time. Our findings are consistent with the notion that crowding should be considered as a spatio-temporal, and not simply a spatial, effect.

  5. A 1000-year sediment record of recurring hypoxia off the Mississippi River: The potential role of terrestrially-derived organic matter inputs

    USGS Publications Warehouse

    Swarzenski, P.W.; Campbell, P.L.; Osterman, L.E.; Poore, R.Z.

    2008-01-01

    A suite of inorganic and organic geochemical tracers and a low-oxygen tolerant benthic faunal index ('PEB') were measured in a 14C-dated 2+??m long gravity core collected on the Louisiana shelf adjacent to the Mississippi River delta to study potential millennium-scale low-oxygen events. Periodic down-core excursions in the PEB index throughout the core suggest recurring, natural bottom water low-oxygen events that extend back ??? 1000??14C years. Select trace element and biomarker distributions in these same sediments were examined as potential tracers of past hypoxic events and to help distinguish between marine versus terrestrial processes involved in organic carbon production. In discrete sediment horizons where the PEB index was elevated, redox-sensitive vanadium concentrations were consistently depleted, excursions in sedimentary ??13C suggest periodic, preferential terrestrial inputs, and the concentrations of two sterol biomarkers (sitosterol and ??-stigmasterol) also showed concurrent enrichments. If the PEB index successfully records ??? 1000??14C year-scale low-oxygen events, then the distribution of these geochemical tracers can be interpreted to corroborate the view that naturally occurring low-oxygen bottom water conditions have existed on the inner Louisiana continental shelf, not only in recent times, but also over at least the last 1000??14C years. These data support the general hypothesis that historic, low-oxygen bottom water conditions on the Louisiana shelf are likely tied to periods of increased fluvial discharge and associated wetland export in the absence of modern river levees. Enhanced river discharge and associated material export would both stimulate enhanced in situ organic carbon production and foster water column stratification. Such periodic elevated river flows during the last millennium can be linked to climate fluctuations and tropical storm activity. ?? 2008 Elsevier B.V. All rights reserved.

  6. Immune responses of phenoloxidase and superoxide dismutase in the manila clam Venerupis philippinarum challenged with Vibrio tapetis--Part I: Spatio-temporal evolution of enzymes' activities post-infection.

    PubMed

    Le Bris, Cédric; Richard, Gaëlle; Paillard, Christine; Lambert, Christophe; Seguineau, Catherine; Gauthier, Olivier; Pernet, Fabrice; Guérard, Fabienne

    2015-01-01

    Manila clams, Venerupis philippinarum (Adams and Reeve, 1850), were experimentally challenged with two Vibrio tapetis strains: CECT4600T, the causative agent of Brown Ring Disease (BRD); and LP2 supposedly non-pathogenic in V. philippinarum. Changes in phenoloxidase (PO) and superoxide dismutase (SOD), two major enzymes involved in immunity, were studied in two tissues, the mantle and hemolymph for 30 days after infection in the extrapallial cavity. Bacterial infection in V. philippinarum resulted in modulation of PO and SOD activities that was both tissue- and time-dependent. A response at early times was detected in the mantle and was associated with significant increases in PO and SOD activities in LP2- and CECT4600T-challenged clams 36 h post injection. This first response in the mantle could be explained by the proximity to the injection region (extrapallial cavity). In the hemolymph the response occurred at later times and was associated with an increase in PO activity and a decrease in SOD activity. As hemolymph is a circulating fluid, this response delay could be due to an "integration time" needed by the organism to counteract the infection. Injections also impacted PO and SOD activities in both tissues and confirmed a difference in pathogenicity between the two V. tapetis strains.

  7. Emergency Spatiotemporal Shift: The Response of Protein Kinase D to Stress Signals in the Cardiovascular System

    PubMed Central

    Wood, Brent M.; Bossuyt, Julie

    2017-01-01

    Protein Kinase D isoforms (PKD 1-3) are key mediators of neurohormonal, oxidative, and metabolic stress signals. PKDs impact a wide variety of signaling pathways and cellular functions including actin dynamics, vesicle trafficking, cell motility, survival, contractility, energy substrate utilization, and gene transcription. PKD activity is also increasingly linked to cancer, immune regulation, pain modulation, memory, angiogenesis, and cardiovascular disease. This increasing complexity and diversity of PKD function, highlights the importance of tight spatiotemporal control of the kinase via protein–protein interactions, post-translational modifications or targeting via scaffolding proteins. In this review, we focus on the spatiotemporal regulation and effects of PKD signaling in response to neurohormonal, oxidant and metabolic signals that have implications for myocardial disease. Precise targeting of these mechanisms will be crucial in the design of PKD-based therapeutic strategies. PMID:28174535

  8. Spatiotemporal evolution of the completeness magnitude of the Icelandic earthquake catalogue from 1991 to 2013

    NASA Astrophysics Data System (ADS)

    Panzera, Francesco; Mignan, Arnaud; Vogfjörð, Kristin S.

    2016-11-01

    In 1991, a digital seismic monitoring network was installed in Iceland with a digital seismic system and automatic operation. After 20 years of operation, we explore for the first time its nationwide performance by analysing the spatiotemporal variations of the completeness magnitude. We use the Bayesian magnitude of completeness (BMC) method that combines local completeness magnitude observations with prior information based on the density of seismic stations. Additionally, we test the impact of earthquake location uncertainties on the BMC results, by filtering the catalogue using a multivariate analysis that identifies outliers in the hypocentre error distribution. We find that the entire North-to-South active rift zone shows a relatively low magnitude of completeness Mc in the range 0.5-1.0, highlighting the ability of the Icelandic network to detect small earthquakes. This work also demonstrates the influence of earthquake location uncertainties on the spatiotemporal magnitude of completeness analysis.

  9. Computational EEG modelling of decision making under ambiguity reveals spatio-temporal dynamics of outcome evaluation.

    PubMed

    Jollans, Lee; Whelan, Robert; Venables, Louise; Turnbull, Oliver H; Cella, Matteo; Dymond, Simon

    2017-03-15

    Complex human cognition, such as decision-making under ambiguity, is reflected in dynamic spatio-temporal activity in the brain. Here, we combined event-related potentials with computational modelling of the time course of decision-making and outcome evaluation during the Iowa Gambling Task. Measures of choice probability generated using the Prospect Valence Learning Delta (PVL-Delta) model, in addition to objective trial outcomes (outcome magnitude and valence), were applied as regressors in a general linear model of the EEG signal. The resulting three-dimensional spatio-temporal characterization of task-related neural dynamics demonstrated that outcome valence, outcome magnitude, and PVL-Delta choice probability were expressed in distinctly separate event related potentials. Our findings showed that the P3 component was associated with an experience-based measure of outcome expectancy.

  10. Simultaneous spatio-temporal matching pursuit decomposition of evoked brain responses in MEG.

    PubMed

    Kordowski, Paweł; Matysiak, Artur; König, Reinhard; Sielużycki, Cezary

    2017-02-01

    We present a novel approach to the spatio-temporal decomposition of evoked brain responses in magnetoencephalography (MEG) aiming at a sparse representation of the underlying brain activity in terms of spatio-temporal atoms. Our approach is characterized by three attributes which constitute significant improvements with respect to existing approaches: (1) the spatial and temporal decomposition is addressed simultaneously rather than sequentially, with the benefit that source loci and corresponding waveforms can be unequivocally allocated to each other, and, hence, allow a plausible physiological interpretation of the parametrized data; (2) it is free from severe a priori assumptions about the solution space; (3) it comprises an optimization technique for the use of very large spatial and temporal subdirectories to greatly reduce the otherwise enormous computational cost by making use of the Cauchy-Schwarz inequality. We demonstrate the efficiency of the approach with simulations and real MEG data obtained from a subject exposed to a simple auditory stimulus.

  11. Effective use of forensic science in volume crime investigations: identifying recurring themes in the literature.

    PubMed

    Ludwig, Anika; Fraser, Jim

    2014-01-01

    New scientific, technological and legal developments, particularly the introduction of national databases for DNA and fingerprints, have led to increased use of forensic science in the investigation of crime. There is an assumption, and in some instances specific assertions, that such developments bring improvements either in broad criminal justice terms or more narrowly in terms of economic or practical efficiencies. The underlying presumption is that the new technological opportunities will be understood and effectively implemented. This research investigates whether such increases in activity have also been accompanied by improvements in the effective use of forensic science. A systematic review of thirty-six reports published (predominantly in England and Wales) since the 1980s, which have considered the use of forensic science in the investigation of volume crimes, was carried out. These reports have identified a number of recurrent themes that influenced how effectively forensic science was used in investigations. The themes identified included forensic knowledge and training of investigators, communication and information exchange between specialists and investigators, timeliness of forensic results, interagency relationships and deployment of crime scene examiner resources. The research findings suggest that these factors continue to hinder the effective use of forensic science despite technological advances and this paper considers their potential causes.

  12. An Observational Study of the Recurring Formation and Dissipation of a Dynamic Filament

    NASA Astrophysics Data System (ADS)

    Zhou, Guiping; Wang, Jingxiu; Zhang, Jie

    2016-10-01

    Based on observations at the Hα wavelength from the Hinode spacecraft, we report here the detailed process of a dynamical filament that showed repeated appearance and dissipation in a filament channel. First, Hα short fibrils spreading in the pre-formed filament channel joined into longer threads. The joining process was found to be accompanied by small-scale brightening activity, indicating the possible involvement of magnetic reconnection. The forming filament was thickened by merging the neighboring dark threads that were nearly parallel to the axis and also those adjacent to its main endpoints. The formed filament as a single coherent structure only existed for tens of minutes, immediately followed by the dissipation. The dissipation appeared to start with expansion of the filament body, ascending and stripping away of the filament threads, and mass drainage along the legs of the filament. The formation-dissipation process of the filament was repeated three times within the four-hour observational window of Hinode. These observations indicate that the filament structure is highly dynamic. This study provides the observational evidence to confirm the hypothesis of Martin et al. ( Ann. Geophys. 26, 3061, 2008) on the irreversible build-up of magnetic fields in the corona by discrete threads or groups of threads ascending bodily into the corona.

  13. Computer vision profiling of neurite outgrowth dynamics reveals spatiotemporal modularity of Rho GTPase signaling

    PubMed Central

    Fusco, Ludovico; Lefort, Riwal; Smith, Kevin; Benmansour, Fethallah; Gonzalez, German; Barillari, Caterina; Rinn, Bernd; Fleuret, Francois; Fua, Pascal

    2016-01-01

    Rho guanosine triphosphatases (GTPases) control the cytoskeletal dynamics that power neurite outgrowth. This process consists of dynamic neurite initiation, elongation, retraction, and branching cycles that are likely to be regulated by specific spatiotemporal signaling networks, which cannot be resolved with static, steady-state assays. We present NeuriteTracker, a computer-vision approach to automatically segment and track neuronal morphodynamics in time-lapse datasets. Feature extraction then quantifies dynamic neurite outgrowth phenotypes. We identify a set of stereotypic neurite outgrowth morphodynamic behaviors in a cultured neuronal cell system. Systematic RNA interference perturbation of a Rho GTPase interactome consisting of 219 proteins reveals a limited set of morphodynamic phenotypes. As proof of concept, we show that loss of function of two distinct RhoA-specific GTPase-activating proteins (GAPs) leads to opposite neurite outgrowth phenotypes. Imaging of RhoA activation dynamics indicates that both GAPs regulate different spatiotemporal Rho GTPase pools, with distinct functions. Our results provide a starting point to dissect spatiotemporal Rho GTPase signaling networks that regulate neurite outgrowth. PMID:26728857

  14. Fast Variable Structure Stochastic Automaton for Discovering and Tracking Spatiotemporal Event Patterns.

    PubMed

    Zhang, Junqi; Wang, Yuheng; Wang, Cheng; Zhou, MengChu

    2017-04-05

    Discovering and tracking spatiotemporal event patterns have many applications. For example, in a smart-home project, a set of spatiotemporal pattern learning automata are used to monitor a user's repetitive activities, by which the home's automaticity can be promoted while some of his/her burdens can be reduced. Existing algorithms for spatiotemporal event pattern recognition in dynamic noisy environment are based on fixed structure stochastic automata whose state transition function is fixed and predesigned to guarantee their immunity to noise. However, such design is conservative because it needs continuous and identical feedbacks to converge, thus leading to its very low convergence rate. In many real-life applications, such as ambient assisted living, consecutive nonoccurrences of an elder resident's routine activities should be treated with an alert as quickly as possible. On the other hand, no alert should be output even for some occurrences in order to diminish the effects caused by noise. Clearly, confronting a pattern's change, slow speed and low accuracy may degrade a user's life security. This paper proposes a fast and accurate leaning automaton based on variable structure stochastic automata to satisfy the realistic requirements for both speed and accuracy. Bias toward alert is necessary for elder residents while the existing method can only support the bias toward ``no alert.'' This paper introduces a method to allow bias toward alert or no alert to meet a user's specific bias requirement. Experimental results show its better performance than the state-of-the-art methods.

  15. Dissociation of Processing of Featural and Spatiotemporal Information in the Infant Cortex

    PubMed Central

    Wilcox, Teresa; Haslup, Jennifer A.; Boas, David A.

    2010-01-01

    A great deal is known about the development of visual object processing capacities and the neural structures that mediate these capacities in the mature observer. In contrast, little is known about the neural structures that mediate these capacities in the infant or how these structures eventually give rise to mature processing. The present research used near-infrared spectroscopy to investigate neural activation in visual, temporal, and parietal cortex during object processing tasks. Infants aged 5 to 7 months viewed visual events that required processing of the featural (Expt 1) or the spatiotemporal (Expt 2) properties of objects. In Expt 1, different patterns of neural were obtained in temporal cortex in response to shape than color information. In Expt 2, different patterns of neural activation were obtained in parietal cortex in response to spatiotemporal (speed and path of motion) than featural (shape and color) information. These results suggest a dissociation of processing of featural and spatiotemporal information in the infant cortex and provide evidence for early functional specification of the human brain. The outcome of these studies inform brain-behavior models of cognitive development and lay the foundation for systematic investigation of the functional maturation of object processing systems in the infant brain. PMID:20603218

  16. Balm mint extract (Lo-701) for topical treatment of recurring herpes labialis.

    PubMed

    Koytchev, R; Alken, R G; Dundarov, S

    1999-10-01

    A double-blind, placebo-controlled, randomized trial was carried out with the aim of proving efficacy of standardized balm mint cream [active ingredient: 1% Lo-701--dried extract from Melissa officinalis L. leaves (70:1)] for the therapy of herpes simplex labialis. Sixty six patients with a history of recurrent herpes labialis (at least four episodes per year) in one center were treated topically; 34 of them with verum and 32 with placebo. The cream had to be smeared on the affected area four times daily over five days. A combined symptom score of the values for complaints, size of affected area and blisters at day 2 of therapy was formed as the primary target parameter. There was a significant difference in the values of the primary target parameter between both treatment groups: verum 4.03 +/- 0.33 (3.0); placebo 4.94 +/- 0.40 (5.0); values given are mean +/- SEM (median) of the symptoms score on day 2 of therapy. The tested formulation is effective for the treatment of herpes simplex labialis. The significant difference in the combined symptom score on the second day of treatment is of particular importance having in mind that the complaints in patients suffering from herpes labialis are usually most intensive at that time. In addition to the shortening of the healing period, the prevention of a spreading of the infection and the rapid effect on typical symptoms of herpes like itching, tingling, burning, stabbing, swelling, tautness and erythema, the balm mint cream has a further advantage. The different mechanism of action of the balm mint extract rules out the development of resistance of the herpes virus. Some indication exists that the intervals between the periods with herpes might be prolonged with balm mint cream treatment.

  17. Defective organellar acidification as a cause of cystic fibrosis lung disease: reexamination of a recurring hypothesis

    PubMed Central

    Haggie, Peter M.; Verkman, A. S.

    2009-01-01

    The cellular mechanisms by which loss-of-function mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel produce cystic fibrosis (CF) lung disease remain uncertain. Defective organellar function has been proposed as an important determinant in the pathogenesis of CF lung disease. According to one hypothesis, reduced CFTR chloride conductance in organelles in CF impairs their acidification by preventing chloride entry into the organelle lumen, which is needed to balance the positive charge produced by proton entry. According to a different hypothesis, CFTR mutation hyperacidifies organelles by an indirect mechanism involving unregulated sodium efflux through epithelial sodium channels. There are reports of defective Golgi, endosomal and lysosomal acidification in CF epithelial cells, defective phagolysosomal acidification in CF alveolar macrophages, and organellar hyperacidification in CF respiratory epithelial cells. The common theme relating too high or low organellar pH to cellular dysfunction and CF pathogenesis is impaired functioning of organellar enzymes, such as those involved in ceramide metabolism and protein processing in epithelial cells and antimicrobial activity in alveolar macrophages. We review here the evidence for defective organellar acidification in CF. Significant technical and conceptual concerns are discussed regarding the validity of data showing too high/low organellar pH in CF cells, and rigorous measurements of organellar pH in CF cells are reviewed that fail to support defective organellar acidification in CF. Indeed, there is an expanding body of evidence supporting the involvement of non-CFTR chloride channels in organellar acidification. We conclude that biologically significant involvement of CFTR in organellar acidification is unlikely. PMID:19329540

  18. Spatiotemporal drivers of energy expenditure in a coastal marine fish.

    PubMed

    Brownscombe, Jacob W; Cooke, Steven J; Danylchuk, Andy J

    2017-03-01

    Animal behavior and energy expenditure often vary significantly across the landscape, and quantifying energy expenditure over space and time provides mechanistic insight into ecological dynamics. Yet, spatiotemporal variability in energy expenditure has rarely been explored in fully aquatic species such as fish. Our objective was to quantify spatially explicit energy expenditure for a tropical marine teleost fish, bonefish (Albula vulpes), to examine how bonefish energetics vary across landscape features and temporal factors. Using a swim tunnel respirometer, we calibrated acoustic accelerometer transmitters implanted in bonefish to estimate their metabolic rates and energy expenditure, and applied this technology in situ using a fine-scale telemetry system on a heterogeneous reef flat in Puerto Rico. Bonefish energy expenditure varied most among habitats, with significant interactions between habitat and temporal factors (i.e., diel period, tide state, season). The energy expenditure was generally highest in shallow water habitats (i.e., seagrass and reef crest). Variation in activity levels was the main driver of these differences in energy expenditure, which in shallow, nearshore habitats is likely related to foraging. Bonefish moderate energy expenditure across seasonal fluctuations in temperature, by selectively using shallow nearshore habitats at moderate water temperatures that correspond with their scope for activity. Quantifying how animals expend energy in association with environmental and ecological factors can provide important insight into behavioral ecology, with implications for bioenergetics models.

  19. Successful smoking cessation with electronic cigarettes in smokers with a documented history of recurring relapses: a case series

    PubMed Central

    2011-01-01

    Introduction Smoking cessation programs are useful in helping smokers to quit, but smoking is a very difficult addiction to break and the need for novel and effective approaches to smoking cessation interventions is unquestionable. The E-cigarette is a battery-powered electronic nicotine delivery device that may help smokers to remain abstinent during their quit attempt. We report for the first time objective measures of smoking cessation in smokers who experimented with the E-cigarette. Case presentation Three Caucasian smokers (two men aged 47 and 65 years and one woman aged 38 years) with a documented history of recurring relapses were able to quit and to remain abstinent for at least six months after taking up an E-cigarette. Conclusions This is the first time that objective measures of smoking cessation are reported for smokers who quit successfully after using an E-cigarette. This was accomplished in smokers who repeatedly failed in previous attempts with professional smoking cessation assistance using the usual nicotine dependence treatments and smoking cessation counselling. PMID:22185668

  20. Benign phyllodes tumor of the breast recurring as a malignant phyllodes tumor and spindle cell metaplastic carcinoma.

    PubMed

    Muller, Kristen E; Tafe, Laura J; de Abreu, Francine B; Peterson, Jason D; Wells, Wendy A; Barth, Richard J; Marotti, Jonathan D

    2015-02-01

    We report a unique case of a 59-year-old woman diagnosed with a benign phyllodes tumor (PT), which recurred twice in the same location over a 7-year period: first as a malignant PT and then as a malignant PT with coexisting spindle cell metaplastic breast carcinoma (MBC). The MBC was differentiated from the malignant PT by expression of cytokeratins (CKs) AE1/AE3, CK MNF-116, CK 5/6, and p63. Somatic mutation analysis using a next-generation sequencing platform revealed a shared mutation in F-box and WD repeat domain containing 7, a tumor suppressor gene that encodes a ubiquitin ligase-associated protein, in the original benign PT and the first recurrent malignant PT. Chromosomal microarray analysis showed shared genetic gains and losses between the malignant PT and MBC. This case highlights the utility of immunohistochemistry to differentiate malignant PT from spindle cell MBC, describes a novel mutation in PT, and demonstrates a biologic relationship between these 2 entities.

  1. Spatio-Temporal Clustering of Monitoring Network

    NASA Astrophysics Data System (ADS)

    Hussain, I.; Pilz, J.

    2009-04-01

    Pakistan has much diversity in seasonal variation of different locations. Some areas are in desserts and remain very hot and waterless, for example coastal areas are situated along the Arabian Sea and have very warm season and a little rainfall. Some areas are covered with mountains, have very low temperature and heavy rainfall; for instance Karakoram ranges. The most important variables that have an impact on the climate are temperature, precipitation, humidity, wind speed and elevation. Furthermore, it is hard to find homogeneous regions in Pakistan with respect to climate variation. Identification of homogeneous regions in Pakistan can be useful in many aspects. It can be helpful for prediction of the climate in the sub-regions and for optimizing the number of monitoring sites. In the earlier literature no one tried to identify homogeneous regions of Pakistan with respect to climate variation. There are only a few papers about spatio-temporal clustering of monitoring network. Steinhaus (1956) presented the well-known K-means clustering method. It can identify a predefined number of clusters by iteratively assigning centriods to clusters based. Castro et al. (1997) developed a genetic heuristic algorithm to solve medoids based clustering. Their method is based on genetic recombination upon random assorting recombination. The suggested method is appropriate for clustering the attributes which have genetic characteristics. Sap and Awan (2005) presented a robust weighted kernel K-means algorithm incorporating spatial constraints for clustering climate data. The proposed algorithm can effectively handle noise, outliers and auto-correlation in the spatial data, for effective and efficient data analysis by exploring patterns and structures in the data. Soltani and Modarres (2006) used hierarchical and divisive cluster analysis to categorize patterns of rainfall in Iran. They only considered rainfall at twenty-eight monitoring sites and concluded that eight clusters

  2. Transient Spatiotemporal Chaos in a Synaptically Coupled Neural Network

    NASA Astrophysics Data System (ADS)

    Lafranceschina, Jacopo; Wackerbauer, Renate

    2014-03-01

    Spatiotemporal chaos is transient in a diffusively coupled Morris-Lecar neural network. This study shows that the addition of synaptic coupling in the ring network reduces the average lifetime of spatiotemporal chaos for small to intermediate coupling strength and almost all numbers of synapses. For large coupling strength, close to the threshold of excitation, the average lifetime increases beyond the value for only diffusive coupling, and the collapse to the rest state dominates over the collapse to a traveling pulse state. The regime of spatiotemporal chaos is characterized by a slightly increasing Lyaponov exponent and degree of phase coherence as the number of synaptic links increases. The presence of transient spatiotemporal chaos in a network of coupled neurons and the associated chaotic saddle provides a possibility for switching between metastable states observed in information processing and brain function. This research is supported by the University of Alaska Fairbanks.

  3. Transition of spatiotemporal patterns in neuronal networks with chemical synapses

    NASA Astrophysics Data System (ADS)

    Wang, Rong; Li, Jiajia; Du, Mengmeng; Lei, Jinzhi; Wu, Ying

    2016-11-01

    In mammalian neocortex plane waves, spiral and irregular waves appear alternately. In this paper, we study the transition of spatiotemporal patterns in neuronal networks in which neurons are coupled via two types of chemical synapses: fast excitatory synapse and fast inhibitory synapse. Our results indicate that the fast excitatory synapse connection is easier to induce regular spatiotemporal patterns than fast inhibitory synapse connection, and the mechanism is discussed through bifurcation analysis of a single neuron. We introduce the permutation entropy as a measure of network firing complexity to study the mechanisms of formation and transition of spatiotemporal patterns. Our calculations show that the spatiotemporal pattern transitions are closely connected to a sudden decrease in the firing complexity of neuronal networks, and the neuronal networks with fast excitatory synapses have higher firing complexity than those with fast inhibitory synapses.

  4. Neural mechanisms of spatiotemporal signal processing

    NASA Astrophysics Data System (ADS)

    Khanbabaie Shoub, Shaban (Reza)

    We have studied the synaptic, dendritic, and network mechanisms of spatiotemporal signal processing underlying the computation of visual motion in the avian tectum. Such mechanisms are critical for information processing in all vertebrates, but have been difficult to elucidate in mammals because of anatomical limitations. We have therefore developed a chick tectal slice preparation, which has features that help us circumvent these limitations. Using single-electrode multi-pulse synaptic stimulation experiments we found that the SGC-I cell responds to synaptic stimulation in a binary manner and its response is phasic in a time dependent probabilistic manner over large time scales. Synaptic inputs at two locations typically interact in a mutually exclusive manner when delivered within the "interaction time" of approximately 30 ms. Then we constructed a model of SGC-I cell and the retinal inputs to examine the role of the observed non-linear cellular properties in shaping the response of SGC-I neurons to assumed retinal representations of dynamic spatiotemporal visual stimuli. We found that by these properties, SGC-I cells can classify different stimuli. Especially without the phasic synaptic signal transfer the model SGC-I cell fails to distinguish between the static stationary stimuli and dynamic spatiotemporal stimuli. Based on one-site synaptic response probability and the assumption of independent neighboring dendritic endings we predicted the response probability of SGC-I cells to multiple synaptic inputs. We tested this independence-based model prediction and found that the independency assumption is not valid. The measured SGC-I response probability to multiple synaptic inputs does not increase with the number of synaptic inputs. The presence of GABAergic horizontal cells in layer 5 suggest an inhibitory effect of these cells on the SGC-I retino-tectal synaptic responses. In our experiment we found that the measured SGC-I response probability to multiple

  5. Spatiotemporal localized modes in PT-symmetric optical media

    NASA Astrophysics Data System (ADS)

    Wang, Yue-Yue; Dai, Chao-Qing; Wang, Xiao-Gang

    2014-09-01

    We firstly obtain spatiotemporal localized mode solutions of a (3+1)-dimensional nonlinear Schrödinger equation in PT-symmetric potentials, and then discuss the linear stability of LMs, which are also tested by means of direct simulations. Moreover, phase switches and transverse power-flow density associated with these localized modes have also been examined. At last, we investigate the dynamical behaviors of spatiotemporal LMs in three kinds of inhomogeneous media.

  6. Spatiotemporal binary interaction and designer quasi-particle condensates

    NASA Astrophysics Data System (ADS)

    Ramaswamy, Radha; Pattu Sakthi, Vinayagam; Hyun Jong, Shin; Kuppuswamy, Porsezian

    2014-03-01

    We introduce a new integrable model to investigate the dynamics of two component quasi-particle condensates with spatiotemporal interaction strengths. We derive the associated Lax pair of the coupled Gross—Pitaevskii (GP) equation and construct matter wave solitons. We show that the spatiotemporal binary interaction strengths not only facilitate the stabilization of the condensates, but also enables one to fabricate condensates with desirable densities, geometries, and properties, leading to the so-called “designer quasi-particle condensates”.

  7. Manipulation of spatiotemporal photon distribution via chromatic aberration.

    PubMed

    Li, Yuelin; Chemerisov, Sergey

    2008-09-01

    We demonstrate a spatiotemporal laser-pulse-shaping scheme that exploits the chromatic aberration in a dispersive lens. This normally harmful effect transforms the phase modulation into a beam-size modulation at the focal plane. In combination with the intricate diffraction effect via beam apodization, this method provides a spatiotemporal control of photon distribution with an accuracy of diffraction limit on a time scale of femtoseconds.

  8. Spatiotemporal characteristics of flood protection level

    NASA Astrophysics Data System (ADS)

    Tanoue, M.; Ikeuchi, H.; Hirabayashi, Y.

    2015-12-01

    Flooding is the most frequent natural hazard and its global impacts will be rising associated with climate change and socioeconomic growth. So, the understanding of the physical and spatial-temporal patterns of risk drivers (exposure, damage, and flood protection level) are required to conduct effective adaptation and reduce the negative impacts of flooding. Although the understanding of exposure and damage has greatly improved using a combination of numerical model simulation and spatiotemporal distributions of population and asset, that of flood protection level is still lacking in particular spatial patterns. Previous research clarifies its temporal variation and relationship with per-capita income, however they do not consider its spatial variation. Flood protection level was associated with geographical characteristics (e.g., soil type and tectonic zone etc). This study tried to estimate spatiotemporal of flood protection level at country level and discuss about relationship between its spatial patterns and geographical characteristics. Mortality rate (percentage of fatalities in modeled exposed population) and loss rate (percentage of losses in modeled exposed GDP) to fluvial river flooding across the world suggested by Jongmann et al. (2015) were estimated from modeled flood exposure and damage statistics taken from the International Emergency Disasters Database. The result indicated that mortality rate reduced across the world from 1990 to 2005. The degree of its reduction decreased with increasing per-capita income level. On the other hand, loss rate at high income and middle low income levels reduced, while that at middle high income and low income levels drastically increased between 1995 and 2000 due to growth economic and occurrence of serious fluvial river flooding. Spatial distribution of mortality and loss rates were high in East Asia, the western part of South America, and the eastern part of Europe. These regions seem to be corresponded to the

  9. Origin and Spatiotemporal Control of Cuspate Forelands

    NASA Astrophysics Data System (ADS)

    McNinch, J. E.

    2006-12-01

    Cuspate shoreline forms are ubiquitous throughout shorelines of the world and span a wide range in size from sub-meter to 102 kilometers; in grain size from fine to coarse; and in energetic settings from small lakes and lagoons to open ocean beaches with virtually unlimited fetch. Cuspate forelands, with wavelengths ranging from 1-120 km, are found worldwide and are the largest of the rhythmic coastal forms. The origin of cuspate forelands has been debated for well over a century but no theory has emerged that fully explains both the origin and the processes controlling the size and time necessary for development. Despite this uncertainty of spatiotemporal controls, large-scale rhythmic morphology of cuspate forelands strongly suggests that scaling and linkages between physical and sedimentary processes may span many orders of magnitude. The same hydrodynamic forces driving sediment transport at the granular scale, such as wave orbital motion and mean currents, likely play a role in shaping the much larger cuspate shorelines. A survey of passive margin, microtidal shorelines from the US and select locations around the world reveals that cuspate forelands are only found in regions where the predominant wind direction is shore-parallel. Modeling and observations of waves, currents, and sediment accumulation from Cape Lookout, North Carolina indicate that water and sediment are transported well seaward of cuspate foreland promontories by wind-driven and tidal residual currents leading to: 1) the rapid growth of spits and sub-aqueous shoals, 2) elimination of sediment exchange between adjacent littoral cells, and 3) control of the wave diffraction point around the promontories. These results and earlier modeling work related to high-angle waves suggest that wind leads to feedback between waves, currents, and promontory-shoal bathymetry and ultimately defines the size and development time of cuspate forelands. Lastly, a linear relationship between the size of cuspate

  10. Bioimage informatics for understanding spatiotemporal dynamics of cellular processes.

    PubMed

    Yang, Ge

    2013-01-01

    The inner environment of the cell is highly dynamic and heterogeneous yet exquisitely organized. Successful completion of cellular processes within this environment depends on the right molecules or molecular complexes to function at the right place at the right time. Understanding spatiotemporal behaviors of cellular processes is therefore essential to understanding their molecular mechanisms at the systems level. These behaviors are usually visualized and recorded using imaging techniques. However, to infer from them systems-level molecular mechanisms, computational analysis and understanding of recorded image data is crucial, not only for acquiring quantitative behavior measurements but also for comprehending complex interactions among the molecules or molecular complexes involved. The technology of computational analysis and understanding of biological images is often referred to simply as bioimage informatics. This article introduces fundamentals of bioimage informatics for understanding spatiotemporal dynamics of cellular processes and reviews recent advances on this topic. Basic bioimage informatics concepts and techniques for characterizing spatiotemporal cell dynamics are introduced first. Studies on specific cellular processes such as cell migration and signal transduction are then used as examples to analyze and summarize recent advances, with the focus on transforming quantitative measurements of spatiotemporal cellular behaviors into knowledge of underlying molecular mechanisms. Despite the advances made, substantial technological challenges remain, especially in representation of spatiotemporal cellular behaviors and inference of systems-level molecular mechanisms. These challenges are briefly discussed. Overall, understanding spatiotemporal cell dynamics will provide critical insights into how specific cellular processes as well as the entire inner cellular environment are dynamically organized and regulated.

  11. Impaired Spatio-Temporal Predictive Motor Timing Associated with Spinocerebellar Ataxia Type 6

    PubMed Central

    Onuki, Yoshiyuki; Abdelgabar, Abdel R.; Owens, Cullen B.; Picard, Samuel; Willems, Jessica; Boele, Henk-Jan; Gazzola, Valeria; Van der Werf, Ysbrand D.; De Zeeuw, Chris I.

    2016-01-01

    Many daily life activities demand precise integration of spatial and temporal information of sensory inputs followed by appropriate motor actions. This type of integration is carried out in part by the cerebellum, which has been postulated to play a central role in learning and timing of movements. Cerebellar damage due to atrophy or lesions may compromise forward-model processing, in which both spatial and temporal cues are used to achieve prediction for future motor states. In the present study we sought to further investigate the cerebellar contribution to predictive and reactive motor timing, as well as to learning of sequential order and temporal intervals in these tasks. We tested patients with spinocerebellar ataxia type 6 (SCA6) and healthy controls for two related motor tasks; one requiring spatio-temporal prediction of dynamic visual stimuli and another one requiring reactive timing only. We found that healthy controls established spatio-temporal prediction in their responses with high temporal precision, which was absent in the cerebellar patients. SCA6 patients showed lower predictive motor timing, coinciding with a reduced number of correct responses during the ‘anticipatory’ period on the task. Moreover, on the task utilizing reactive motor timing functions, control participants showed both sequence order and temporal interval learning, whereas patients only showed sequence order learning. These results suggest that SCA6 affects predictive motor timing and temporal interval learning. Our results support and highlight cerebellar contribution to timing and argue for cerebellar engagement during spatio-temporal prediction of upcoming events. PMID:27571363

  12. Characteristics, processes, and causes of the spatio-temporal variabilities of the East Asian monsoon system

    NASA Astrophysics Data System (ADS)

    Huang, Ronghui; Chen, Jilong; Wang, Lin; Lin, Zhongda

    2012-09-01

    Recent advances in the study of the characteristics, processes, and causes of spatio-temporal variabilities of the East Asian monsoon (EAM) system are reviewed in this paper. The understanding of the EAM system has improved in many aspects: the basic characteristics of horizontal and vertical structures, the annual cycle of the East Asian summer monsoon (EASM) system and the East Asian winter monsoon (EAWM) system, the characteristics of the spatio-temporal variabilities of the EASM system and the EAWM system, and especially the multiple modes of the EAM system and their spatio-temporal variabilities. Some new results have also been achieved in understanding the atmosphere-ocean interaction and atmosphere-land interaction processes that affect the variability of the EAM system. Based on recent studies, the EAM system can be seen as more than a circulation system, it can be viewed as an atmosphere-ocean-land coupled system, namely, the EAM climate system. In addition, further progress has been made in diagnosing the internal physical mechanisms of EAM climate system variability, especially regarding the characteristics and properties of the East Asia-Pacific (EAP) teleconnection over East Asia and the North Pacific, the "Silk Road" teleconnection along the westerly jet stream in the upper troposphere over the Asian continent, and the dynamical effects of quasi-stationary planetary wave activity on EAM system variability. At the end of the paper, some scientific problems regarding understanding the EAM system variability are proposed for further study.

  13. Neurogenomic signatures of spatiotemporal memories in time-trained forager honey bees.

    PubMed

    Naeger, Nicholas L; Van Nest, Byron N; Johnson, Jennifer N; Boyd, Sam D; Southey, Bruce R; Rodriguez-Zas, Sandra L; Moore, Darrell; Robinson, Gene E

    2011-03-15

    Honey bees can form distinct spatiotemporal memories that allow them to return repeatedly to different food sources at different times of day. Although it is becoming increasingly clear that different behavioral states are associated with different profiles of brain gene expression, it is not known whether this relationship extends to states that are as dynamic and specific as those associated with foraging-related spatiotemporal memories. We tested this hypothesis by training different groups of foragers from the same colony to collect sucrose solution from one of two artificial feeders; each feeder was in a different location and had sucrose available at a different time, either in the morning or afternoon. Bees from both training groups were collected at both the morning and afternoon training times to result in one set of bees that was undergoing stereotypical food anticipatory behavior and another that was inactive for each time of day. Between the two groups with the different spatiotemporal memories, microarray analysis revealed that 1329 genes were differentially expressed in the brains of honey bees. Many of these genes also varied with time of day, time of training or state of food anticipation. Some of these genes are known to be involved in a variety of biological processes, including metabolism and behavior. These results indicate that distinct spatiotemporal foraging memories in honey bees are associated with distinct neurogenomic signatures, and the decomposition of these signatures into sets of genes that are also influenced by time or activity state hints at the modular composition of this complex neurogenomic phenotype.

  14. Automatic spatiotemporal matching of detected pleural thickenings

    NASA Astrophysics Data System (ADS)

    Chaisaowong, Kraisorn; Keller, Simon Kai; Kraus, Thomas

    2014-01-01

    Pleural thickenings can be found in asbestos exposed patient's lung. Non-invasive diagnosis including CT imaging can detect aggressive malignant pleural mesothelioma in its early stage. In order to create a quantitative documentation of automatic detected pleural thickenings over time, the differences in volume and thickness of the detected thickenings have to be calculated. Physicians usually estimate the change of each thickening via visual comparison which provides neither quantitative nor qualitative measures. In this work, automatic spatiotemporal matching techniques of the detected pleural thickenings at two points of time based on the semi-automatic registration have been developed, implemented, and tested so that the same thickening can be compared fully automatically. As result, the application of the mapping technique using the principal components analysis turns out to be advantageous than the feature-based mapping using centroid and mean Hounsfield Units of each thickening, since the resulting sensitivity was improved to 98.46% from 42.19%, while the accuracy of feature-based mapping is only slightly higher (84.38% to 76.19%).

  15. Contextualized trajectory parsing with spatiotemporal graph.

    PubMed

    Liu, Xiaobai; Lin, Liang; Jin, Hai

    2013-12-01

    This work investigates how to automatically parse object trajectories in surveillance videos, which aims at jointly solving three subproblems: 1) spatial segmentation, 2) temporal tracking, and 3) object categorization. We present a novel representation spatiotemporal graph (ST-Graph) in which: 1) Graph nodes express the motion primitives, each representing a short sequence of small-size patches over consecutive images, and 2) every two neighbor nodes are linked with either a positive edge or a negative edge to describe their collaborative or exclusive relationship of belonging to the same object trajectory. Phrasing the trajectory parsing as a graph multicoloring problem, we propose a unified probabilistic formulation to integrate various types of context knowledge as informative priors. An efficient composite cluster sampling algorithm is employed in search of the optimal solution by exploiting both the collaborative and the exclusive relationships between nodes. The proposed framework is evaluated over challenging videos from public datasets, and results show that it can achieve state-of-the-art tracking accuracy.

  16. Network Analysis Using Spatio-Temporal Patterns

    NASA Astrophysics Data System (ADS)

    Miranda, Gisele H. B.; Machicao, Jeaneth; Bruno, Odemir M.

    2016-08-01

    Different network models have been proposed along the last years inspired by real-world topologies. The characterization of these models implies the understanding of the underlying network phenomena, which accounts structural and dynamic properties. Several mathematical tools can be employed to characterize such properties as Cellular Automata (CA), which can be defined as dynamical systems of discrete nature composed by spatially distributed units governed by deterministic rules. In this paper, we proposed a method based on the modeling of one specific CA over distinct network topologies in order to perform the classification of the network model. The proposed methodology consists in the modeling of a binary totalistic CA over a network. The transition function that governs each CA cell is based on the density of living neighbors. Secondly, the distribution of the Shannon entropy is obtained from the evolved spatio-temporal pattern of the referred CA and used as a network descriptor. The experiments were performed using a dataset composed of four different types of networks: random, small-world, scale-free and geographical. We also used cross-validation for training purposes. We evaluated the accuracy of classification as a function of the initial number of living neighbors, and, also, as a function of a threshold parameter related to the density of living neighbors. The results show high accuracy values in distinguishing among the network models which demonstrates the feasibility of the proposed method.

  17. Spatiotemporal directional analysis of 4D echocardiography

    NASA Astrophysics Data System (ADS)

    Angelini-Casadevall, Elsa D.; Laine, Andrew F.; Takuma, Shin; Homma, Shunichi

    2000-12-01

    Speckle noise corrupts ultrasonic data by introducing sharp changes in an echocardiographic image intensity profile, while attenuation alters the intensity of equally significant cardiac structures. These properties introduce inhomogeneity in the spatial domain and suggests that measures based on phase information rather than intensity are more appropriate for denoising and cardiac border detection. The present analysis method relies on the expansion of temporal ultrasonic volume data on complex exponential wavelet-like basis functions called Brushlets. These basis functions decompose a signal into distinct patterns of oriented textures. Projected coefficients are associated with distinct 'brush strokes' of a particular size and orientation. 4D overcomplete brushlet analysis is applied to temporal echocardiographic values. We show that adding the time dimension in the analysis dramatically improves the quality and robustness of the method without adding complexity in the design of a segmentation tool. We have investigated mathematical and empirical methods for identifying the most 'efficient' brush stroke sizes and orientations for decomposition and reconstruction on both phantom and clinical data. In order to determine the 'best tiling' or equivalently, the 'best brushlet basis', we use an entorpy-based information cost metric function. Quantitative validation and clinical applications of this new spatio-temporal analysis tool are reported for balloon phantoms and clinical data sets.

  18. Spatio-temporal statistical models for river monitoring networks.

    PubMed

    Clement, L; Thas, O; Vanrolleghem, P A; Ottoy, J P

    2006-01-01

    When introducing new wastewater treatment plants (WWTP), investors and policy makers often want to know if there indeed is a beneficial effect of the installation of a WWTP on the river water quality. Such an effect can be established in time as well as in space. Since both temporal and spatial components affect the output of a monitoring network, their dependence structure has to be modelled. River water quality data typically come from a river monitoring network for which the spatial dependence structure is unidirectional. Thus the traditional spatio-temporal models are not appropriate, as they cannot take advantage of this directional information. In this paper, a state-space model is presented in which the spatial dependence of the state variable is represented by a directed acyclic graph, and the temporal dependence by a first-order autoregressive process. The state-space model is extended with a linear model for the mean to estimate the effect of the activation of a WWTP on the dissolved oxygen concentration downstream.

  19. Understanding the spatiotemporal pattern of grazing cattle movement

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Jurdak, Raja

    2016-08-01

    Understanding the drivers of animal movement is significant for ecology and biology. Yet researchers have so far been unable to fully understand these drivers, largely due to low data resolution. In this study, we analyse a high-frequency movement dataset for a group of grazing cattle and investigate their spatiotemporal patterns using a simple two-state ‘stop-and-move’ mobility model. We find that the dispersal kernel in the moving state is best described by a mixture exponential distribution, indicating the hierarchical nature of the movement. On the other hand, the waiting time appears to be scale-invariant below a certain cut-off and is best described by a truncated power-law distribution, suggesting that the non-moving state is governed by time-varying dynamics. We explore possible explanations for the observed phenomena, covering factors that can play a role in the generation of mobility patterns, such as the context of grazing environment, the intrinsic decision-making mechanism or the energy status of different activities. In particular, we propose a new hypothesis that the underlying movement pattern can be attributed to the most probable observable energy status under the maximum entropy configuration. These results are not only valuable for modelling cattle movement but also provide new insights for understanding the underlying biological basis of grazing behaviour.

  20. Stable weak-light ultraslow spatiotemporal solitons via atomic coherence

    SciTech Connect

    Li Huijun; Wu Yuanpo; Huang Guoxiang

    2011-09-15

    We propose a scheme to generate stable ultraslow three-dimensional spatiotemporal optical solitons, or ultraslow optical bullets, at very low light levels via atomic coherence. The system we consider is an ensemble of resonant, lifetime-broadened N-type four-level atoms, working in a regime of electromagnetically induced transparency. Due to the quantum interference effect induced by a control field, the absorption of a probe field is largely suppressed. Moreover, the Kerr nonlinearity is greatly enhanced, and the dispersion property of the probe field is drastically changed. Using a method of multiple scales, we derive two coupled nonlinear envelope equations controlling the evolution of the envelopes of the probe field and an assisted field. We show that under certain conditions the envelope of the probe field satisfies a three-dimensional nonlinear Schroedinger equation and the envelope of the assisted field obeys a linear Helmholtz equation. We obtain various optical bullet solutions for the probe-field envelope and demonstrate that such optical bullets have many novel features, including very slow propagating velocity and very low generation power. In addition, they can be actively controlled and manipulated by adjusting system parameters. The stabilization of the optical bullets obtained can be easily realized by the trapping potential contributed by the assisted field, which is also investigated in detail.

  1. Spatiotemporal properties of microsaccades: Model predictions and experimental tests

    NASA Astrophysics Data System (ADS)

    Zhou, Jian-Fang; Yuan, Wu-Jie; Zhou, Zhao

    2016-10-01

    Microsaccades are involuntary and very small eye movements during fixation. Recently, the microsaccade-related neural dynamics have been extensively investigated both in experiments and by constructing neural network models. Experimentally, microsaccades also exhibit many behavioral properties. It’s well known that the behavior properties imply the underlying neural dynamical mechanisms, and so are determined by neural dynamics. The behavioral properties resulted from neural responses to microsaccades, however, are not yet understood and are rarely studied theoretically. Linking neural dynamics to behavior is one of the central goals of neuroscience. In this paper, we provide behavior predictions on spatiotemporal properties of microsaccades according to microsaccade-induced neural dynamics in a cascading network model, which includes both retinal adaptation and short-term depression (STD) at thalamocortical synapses. We also successfully give experimental tests in the statistical sense. Our results provide the first behavior description of microsaccades based on neural dynamics induced by behaving activity, and so firstly link neural dynamics to behavior of microsaccades. These results indicate strongly that the cascading adaptations play an important role in the study of microsaccades. Our work may be useful for further investigations of the microsaccadic behavioral properties and of the underlying neural dynamical mechanisms responsible for the behavioral properties.

  2. Understanding the spatiotemporal pattern of grazing cattle movement

    PubMed Central

    Zhao, Kun; Jurdak, Raja

    2016-01-01

    Understanding the drivers of animal movement is significant for ecology and biology. Yet researchers have so far been unable to fully understand these drivers, largely due to low data resolution. In this study, we analyse a high-frequency movement dataset for a group of grazing cattle and investigate their spatiotemporal patterns using a simple two-state ‘stop-and-move’ mobility model. We find that the dispersal kernel in the moving state is best described by a mixture exponential distribution, indicating the hierarchical nature of the movement. On the other hand, the waiting time appears to be scale-invariant below a certain cut-off and is best described by a truncated power-law distribution, suggesting that the non-moving state is governed by time-varying dynamics. We explore possible explanations for the observed phenomena, covering factors that can play a role in the generation of mobility patterns, such as the context of grazing environment, the intrinsic decision-making mechanism or the energy status of different activities. In particular, we propose a new hypothesis that the underlying movement pattern can be attributed to the most probable observable energy status under the maximum entropy configuration. These results are not only valuable for modelling cattle movement but also provide new insights for understanding the underlying biological basis of grazing behaviour. PMID:27555220

  3. Recurring features of mid-Miocene transitional geomagnetic field behavior: Observations from NE Nevada and SE Oregon

    NASA Astrophysics Data System (ADS)

    Bogue, S. W.; Glen, J. M. G.

    2014-12-01

    Paleomagnetic results from a 150m thick stack of 15.2 my old lava flows in the Sheep Creek Range (north central Nevada; 40.7N, 243.2E) show that distinctive aspects of the reversing geomagnetic field can recur after 1.5 million years. The Sheep Creek lavas preserve a partial record of what is likely the C5Br-C5Bn geomagnetic reversal. That event occurred 1.5 million years and five polarity switches after reversal (C5Cr-C5Cn) recorded in great detail at Steens Mountain in SE Oregon. During both transitions, the VGP made repeat visits to low latitude positions in South America and near Africa although in different order. This behavior implies a control that varies over a timescale much longer that associated with flow in the outer core (~60 yrs), presumably lateral variations in lower mantle temperature or topography on the core-mantle boundary. Furthermore, the field in both reversals moved from clearly transitional to normal-polarity-like (i.e., down and north) directions before "rebounding" to intermediate directions. It has been suggested recently (Valet et al., Nature 2012) that this kind of behavior (i.e., directional change in the form of precursor- main polarity switch-rebound) may be a systematic aspect of transitional field behavior, a suggestion reinforced by these new observations. The distinctive, two component magnetization of a particular lava flow in the Sheep Creek section has been interpreted by Bogue and Glen (GRL, 2010) as evidence of directional change (~1 deg/week) orders of magnitude faster than normal secular variation. If the field was strong at the end of the directional change, then a large change in the local geomagnetic field vector is implied by the directional data for any initial field strength. Preliminary paleointensity experiments aimed at resolving this aspect of the record are in progress.

  4. Delayed kindling development after rapidly recurring seizures: relation to mossy fiber sprouting and neurotrophin, GAP-43 and dynorphin gene expression.

    PubMed

    Elmér, E; Kokaia, M; Kokaia, Z; Ferencz, I; Lindvall, O

    1996-03-11

    Development of kindling and mossy fiber sprouting, and changes of gene expression were studied after 40 seizures produced during about 3 h by electrical stimulation every 5 min in the ventral hippocampus. As assessed by 5 test stimulations, enhanced responsiveness was present already after 6-24 h but from 1 week post-seizure increased gradually up to 4 weeks without additional stimuli. Sprouting of mossy fibers in the dentate gyrus was demonstrated only at 4 weeks with Timm's staining. In situ hybridization showed a transient increase (maximum at 2 h) of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), TrkB and TrkC mRNA levels and reduction (maximum at 12-24 h) of neurotrophin-3 (NT-3) mRNA expression in dentate granule cells after the seizures. In addition, BDNF mRNA levels were elevated in CA1 and CA3 regions, amygdala and piriform cortex. Marked increases of mRNA for growth-associated protein (GAP-43), with maximum expression at 12-24 h, were observed in dentate granule cells and in amygdala-piriform cortex. Dynorphin mRNA levels showed biphasic changes in dentate granule cells with an increase at 2 h followed by a decrease at 24 h. No long-term alterations of gene expression were observed. These findings indicate that increased responsiveness develops rapidly after recurring seizures but that the kindled state is reached gradually in about 4 weeks. Mossy fiber sprouting occurs in parallel to epileptogenesis and may play a causative role. Short-term changes of neurotrophin and Trk, GAP-43 and dynorphin mRNA levels and the assumed alterations of the corresponding proteins could trigger structural rearrangements underlying kindling but might also contribute to the initial increase of seizure susceptibility.

  5. How to Link Brain and Experience? Spatiotemporal Psychopathology of the Lived Body

    PubMed Central

    Northoff, Georg; Stanghellini, Giovanni

    2016-01-01

    The focus of the present article is on sketching a psychopathology of the body in schizophrenia and linking it to brain activity. This is done providing converging data from psychopathological evidence (phenomenal), phenomenological contructs (trans-phenomenal) and neuroscientific measures (pre-phenomenal). The phenomenal level is the detailed documentation of the patients’ subjective anomalous experiences. These phenomena are explicit contents in the patients’ field of consciousness. The trans-phenomenal level targets the implicit yet operative matrix that underlies these anomalous subjective experiences. Abnormal phenomena are viewed as expressions of a modification of trans-phenomenal matrix, that is, in terms of an abnormal synthesis or integration through time of intero-, proprio- and extero-ceptive stimuli. Finally, we link the abnormalities of the trans-phenomenal matrix to pre-phenomenal alterations of the brain resting state and of its spatio-temporal organization, as documented by neurobiological methods providing spatial and temporal resolution of intrinsic brain activity (with many features of the resting state remaining yet unclear though). Based on phenomenological research, the body in schizophrenia is typically experienced in an itemized way as an object external to one’s self and unrelated to events in the external world. Based on neurobiological data, we tentatively hypothesize that such anomalies of the lived body are related to decreased integration between intero-, extero- and proprioceptive experiences by the brain’s spontaneous activity and its temporal structure. Taken all together, this suggests that we view abnormalities of bodily experience in terms of their underlying abnormal spatiotemporal features which, as we suppose, can be traced back to the spatiotemporal features of the brain’s spontaneous activity. PMID:27199695

  6. Spatiotemporal modeling of node temperatures in supercomputers

    DOE PAGES

    Storlie, Curtis Byron; Reich, Brian James; Rust, William Newton; ...

    2016-06-10

    Los Alamos National Laboratory (LANL) is home to many large supercomputing clusters. These clusters require an enormous amount of power (~500-2000 kW each), and most of this energy is converted into heat. Thus, cooling the components of the supercomputer becomes a critical and expensive endeavor. Recently a project was initiated to investigate the effect that changes to the cooling system in a machine room had on three large machines that were housed there. Coupled with this goal was the aim to develop a general good-practice for characterizing the effect of cooling changes and monitoring machine node temperatures in this andmore » other machine rooms. This paper focuses on the statistical approach used to quantify the effect that several cooling changes to the room had on the temperatures of the individual nodes of the computers. The largest cluster in the room has 1,600 nodes that run a variety of jobs during general use. Since extremes temperatures are important, a Normal distribution plus generalized Pareto distribution for the upper tail is used to model the marginal distribution, along with a Gaussian process copula to account for spatio-temporal dependence. A Gaussian Markov random field (GMRF) model is used to model the spatial effects on the node temperatures as the cooling changes take place. This model is then used to assess the condition of the node temperatures after each change to the room. The analysis approach was used to uncover the cause of a problematic episode of overheating nodes on one of the supercomputing clusters. Lastly, this same approach can easily be applied to monitor and investigate cooling systems at other data centers, as well.« less

  7. Spatiotemporal modeling of node temperatures in supercomputers

    SciTech Connect

    Storlie, Curtis Byron; Reich, Brian James; Rust, William Newton; Ticknor, Lawrence O.; Bonnie, Amanda Marie; Montoya, Andrew J.; Michalak, Sarah E.

    2016-06-10

    Los Alamos National Laboratory (LANL) is home to many large supercomputing clusters. These clusters require an enormous amount of power (~500-2000 kW each), and most of this energy is converted into heat. Thus, cooling the components of the supercomputer becomes a critical and expensive endeavor. Recently a project was initiated to investigate the effect that changes to the cooling system in a machine room had on three large machines that were housed there. Coupled with this goal was the aim to develop a general good-practice for characterizing the effect of cooling changes and monitoring machine node temperatures in this and other machine rooms. This paper focuses on the statistical approach used to quantify the effect that several cooling changes to the room had on the temperatures of the individual nodes of the computers. The largest cluster in the room has 1,600 nodes that run a variety of jobs during general use. Since extremes temperatures are important, a Normal distribution plus generalized Pareto distribution for the upper tail is used to model the marginal distribution, along with a Gaussian process copula to account for spatio-temporal dependence. A Gaussian Markov random field (GMRF) model is used to model the spatial effects on the node temperatures as the cooling changes take place. This model is then used to assess the condition of the node temperatures after each change to the room. The analysis approach was used to uncover the cause of a problematic episode of overheating nodes on one of the supercomputing clusters. Lastly, this same approach can easily be applied to monitor and investigate cooling systems at other data centers, as well.

  8. Neuronal Cell Fate Specification by the Convergence of Different Spatiotemporal Cues on a Common Terminal Selector Cascade

    PubMed Central

    Rubio-Ferrera, Irene; Millán-Crespo, Irene; Contero-García, Patricia; Bahrampour, Shahrzad

    2016-01-01

    Specification of the myriad of unique neuronal subtypes found in the nervous system depends upon spatiotemporal cues and terminal selector gene cascades, often acting in sequential combinatorial codes to determine final cell fate. However, a specific neuronal cell subtype can often be generated in different parts of the nervous system and at different stages, indicating that different spatiotemporal cues can converge on the same terminal selectors to thereby generate a similar cell fate. However, the regulatory mechanisms underlying such convergence are poorly understood. The Nplp1 neuropeptide neurons in the Drosophila ventral nerve cord can be subdivided into the thoracic-ventral Tv1 neurons and the dorsal-medial dAp neurons. The activation of Nplp1 in Tv1 and dAp neurons depends upon the same terminal selector cascade: col>ap/eya>dimm>Nplp1. However, Tv1 and dAp neurons are generated by different neural progenitors (neuroblasts) with different spatiotemporal appearance. Here, we find that the same terminal selector cascade is triggered by Kr/pdm>grn in dAp neurons, but by Antp/hth/exd/lbe/cas in Tv1 neurons. Hence, two different spatiotemporal combinations can funnel into a common downstream terminal selector cascade to determine a highly related cell fate. PMID:27148744

  9. Spatio-temporal networks: reachability, centrality and robustness

    PubMed Central

    Musolesi, Mirco

    2016-01-01

    Recent advances in spatial and temporal networks have enabled researchers to more-accurately describe many real-world systems such as urban transport networks. In this paper, we study the response of real-world spatio-temporal networks to random error and systematic attack, taking a unified view of their spatial and temporal performance. We propose a model of spatio-temporal paths in time-varying spatially embedded networks which captures the property that, as in many real-world systems, interaction between nodes is non-instantaneous and governed by the space in which they are embedded. Through numerical experiments on three real-world urban transport systems, we study the effect of node failure on a network's topological, temporal and spatial structure. We also demonstrate the broader applicability of this framework to three other classes of network. To identify weaknesses specific to the behaviour of a spatio-temporal system, we introduce centrality measures that evaluate the importance of a node as a structural bridge and its role in supporting spatio-temporally efficient flows through the network. This exposes the complex nature of fragility in a spatio-temporal system, showing that there is a variety of failure modes when a network is subject to systematic attacks. PMID:27429776

  10. Spatiotemporal integration of tactile patterns along and across fingers.

    PubMed

    Trojan, Jörg; Heil, Maruschka; Maihöfner, Christian; Hölzl, Rupert; Kleinböhl, Dieter; Flor, Herta; Benrath, Justus

    2014-01-01

    The volar sides of the fingers can be seen as the haptic counterpart to the fovea for visual perception. This study assessed the localisation of individual tactile stimuli and spatiotemporal patterns presented to the volar side of the fingers. Participants performed the localisation task by pointing at the perceived positions with a 3D tracker. Based on the pointing data, perceptual maps were devised in which perceived positions, their relationship to each other and to veridical stimulus positions could be analysed. Participants were able to accurately and consistently report the locations of the stimuli. Localisation of stimuli presented within a spatiotemporal pattern generally differed from localization of individual stimuli presented to the same positions. In most cases, stimuli were perceived as being spatially closer when they were presented within a spatiotemporal pattern compared to when being presented individually. Spatiotemporal integration along the fingers followed the predictions of the sensory saltation paradigm: The shorter the temporal delay between the two stimuli, the closer together they were perceived. For spatiotemporal patterns across fingers, the results were inconclusive: No general relationship between temporal delay and the difference between the perceived positions could be demonstrated, presumably because the effect could only be elicited in some finger combinations. Temporal delay did have, however, an effect on overall lateral shifts in localisation.

  11. Basic instinct undressed: early spatiotemporal processing for primary sexual characteristics.

    PubMed

    Legrand, Lore B; Del Zotto, Marzia; Tyrand, Rémi; Pegna, Alan J

    2013-01-01

    This study investigates the spatiotemporal dynamics associated with conscious and non-conscious processing of naked and dressed human bodies. To this effect, stimuli of naked men and women with visible primary sexual characteristics, as well as dressed bodies, were presented to 20 heterosexual male and female participants while acquiring high resolution EEG data. The stimuli were either consciously detectable (supraliminal presentations) or were rendered non-conscious through backward masking (subliminal presentations). The N1 event-related potential component was significantly enhanced in participants when they viewed naked compared to dressed bodies under supraliminal viewing conditions. More importantly, naked bodies of the opposite sex produced a significantly greater N1 component compared to dressed bodies during subliminal presentations, when participants were not aware of the stimulus presented. A source localization algorithm computed on the N1 showed that the response for naked bodies in the supraliminal viewing condition was stronger in body processing areas, primary visual areas and additional structures related to emotion processing. By contrast, in the subliminal viewing condition, only visual and body processing areas were found to be activated. These results suggest that naked bodies and primary sexual characteristics are processed early in time (i.e., <200 ms) and activate key brain structures even when they are not consciously detected. It appears that, similarly to what has been reported for emotional faces, sexual features benefit from automatic and rapid processing, most likely due to their high relevance for the individual and their importance for the species in terms of reproductive success.

  12. Basic Instinct Undressed: Early Spatiotemporal Processing for Primary Sexual Characteristics

    PubMed Central

    Legrand, Lore B.; Del Zotto, Marzia; Tyrand, Rémi; Pegna, Alan J.

    2013-01-01

    This study investigates the spatiotemporal dynamics associated with conscious and non-conscious processing of naked and dressed human bodies. To this effect, stimuli of naked men and women with visible primary sexual characteristics, as well as dressed bodies, were presented to 20 heterosexual male and female participants while acquiring high resolution EEG data. The stimuli were either consciously detectable (supraliminal presentations) or were rendered non-conscious through backward masking (subliminal presentations). The N1 event-related potential component was significantly enhanced in participants when they viewed naked compared to dressed bodies under supraliminal viewing conditions. More importantly, naked bodies of the opposite sex produced a significantly greater N1 component compared to dressed bodies during subliminal presentations, when participants were not aware of the stimulus presented. A source localization algorithm computed on the N1 showed that the response for naked bodies in the supraliminal viewing condition was stronger in body processing areas, primary visual areas and additional structures related to emotion processing. By contrast, in the subliminal viewing condition, only visual and body processing areas were found to be activated. These results suggest that naked bodies and primary sexual characteristics are processed early in time (i.e., <200 ms) and activate key brain structures even when they are not consciously detected. It appears that, similarly to what has been reported for emotional faces, sexual features benefit from automatic and rapid processing, most likely due to their high relevance for the individual and their importance for the species in terms of reproductive success. PMID:23894532

  13. New observations of martian southern mid-latitude recurring slope lineae (RSL) imply formation by freshwater subsurface flows

    NASA Astrophysics Data System (ADS)

    Stillman, David E.; Michaels, Timothy I.; Grimm, Robert E.; Harrison, Keith P.

    2014-05-01

    Southern mid-latitude (SML) recurring slope lineae (RSL) are narrow (0.5-5 m) dark albedo features that emanate from bedrock and incrementally lengthen down steep slopes that preferentially face the equator. We observe that SML RSL begin lengthening prior to southern summer at a solar longitude (Ls) of 245° ± 11° when Mars Global Surveyor Thermal Emission Spectrometer (TES)-derived near-maximum surface temperatures are 296 ± 5 K and Mars Reconnaissance Orbiter Mars Climate Sounder (MCS) - and Mars Odyssey Thermal Emission Imaging System (THEMIS)-derived mid-afternoon surface temperatures are >273 K. SML RSL continue to lengthen for 104 ± 38 sols with an average near-maximum surface temperature of 298 ± 5 K. The SML RSL then stop lengthening at Ls = 314° ± 12° when mid-afternoon surface temperatures drop below 273 K. They remain dark for another 116 ± 41 sols (until Ls = 16° ± 14°) as surface temperatures continue to fall. Although the RSL recharge mechanism remains unknown, our observation that the vast majority of RSL lengthen only when mid-afternoon surface temperatures are >273 K supports the hypothesis that they are formed by shallow subsurface liquid water flows without significant freezing-point depression. The number and length of RSL at multiple sites increased dramatically following the Mars Year 28 globe-encircling dust storm. We interpret this increase to be due to warmer subsurface temperatures created by a dust-laden greenhouse effect that may be unique to the southern mid-latitudes near Ls = 270°. Therefore SML RSL flow is quite sensitive to ground temperature and may only occur under favorable orbital parameters when mean insolation during the RSL lengthening season is above that of the current southern mid-latitude mean insolation value. This value is currently at a peak that has not been attained for the last ∼100 ka. Meanwhile, the RSL-poor northern mid-latitude mean insolation is near a minimum and has a value 27% lower than the

  14. Clinical value of magnetoencephalographic spike propagation represented by spatiotemporal source analysis: Correlation with surgical outcome

    PubMed Central

    Tanaka, Naoaki; Peters, Jurriaan M.; Prohl, Anna K.; Takaya, Shigetoshi; Madsen, Joseph R.; Bourgeois, Blaise F.; Dworetzky, Barbara A.; Hämäläinen, Matti S; Stufflebeam, Steven M.

    2014-01-01

    Objective To investigate the correlation between spike propagation represented by spatiotemporal source analysis of magnetoencephalographic (MEG) spikes and surgical outcome in patients with temporal lobe epilepsy. Methods Thirty-seven patients were divided into mesial (n=27) and non-mesial (n=10) groups based on the presurgical evaluation. In each patient, ten ipsilateral spikes were averaged, and spatiotemporal source maps of the averaged spike were obtained by using minimum norm estimate. Regions of interest (ROIs) were created including temporoparietal, inferior frontal, mesial temporal, anterior and posterior part of the lateral temporal cortex. We extracted activation values from the source maps and the threshold was set at half of the maximum activation at the peak latency. The leading and propagated areas of the spike were defined as those ROIs with activation reaching the threshold at the earliest and at the peak latencies, respectively. Surgical outcome was assessed based on Engel's classification. Binary variables were created from leading areas (restricted to the anterior and mesial temporal ROIs or not) and from propagation areas (involving the temporoparietal ROI or not), and for surgical outcome (Class I or not). Fisher's exact test was used for significance testing. Results In total and mesial group, restricted anterior/mesial temporal leading areas were correlated with Class I (p<0.05). Temporoparietal propagation was correlated with Class II-IV (p<0.05). For the non-mesial group, no significant relation was found. Conclusions Spike propagation patterns represented by spatiotemporal source analysis of MEG spikes may provide useful information for prognostic implication in presurgical evaluation of epilepsy. PMID:24315019

  15. Spatio-temporal pattern of EEG in young brain respiration-training children.

    PubMed

    Kim, H R; Kim, S Y; Kim, D J; Kim, Y Y; Park, S K; Chae, J H; Kim, K S; Lee, K H; Lee, S H

    2001-01-01

    We have evaluated the effect of 'Brain Respiration' training on brain activity using Karhunen-Loeve (KL) decomposition as a method for spatio-temporal analysis of the electroencephalogram (EEG). BR training is a form of breath-work to optimize the function of the brain by concentrating Qi energy in the brain. Recently, BR-training has been reported to improve emotional maturity (i.e., EQ), short-term memory and intuition (Yoo et al., 1998). EEG data were taken during BR-training from 12 young BR-trainees (average age: 9.4 years) who had trained for 4 to 14 months, and during relaxation from age matched non-trained children. Spatio-temporal analysis showed a significant difference of EEG dynamics in right prefrontal, right inferior frontal, posterior temporal, parietal and occipital areas between BR-trainees and the control group. Amplitude of eigenvector components of BR-trainees in the areas of frontal, temporal and occipital cortex was larger than that of non-trained children (values were smaller in parietal cortex), with remarkably high amplitude alpha coherence all over the scalp. These results suggest that BR-training possibly activates brain function through changes in the activity of the frontal association area where higher mental integration and creative activities are mediated.

  16. Neural avalanches at the critical point between replay and non-replay of spatiotemporal patterns.

    PubMed

    Scarpetta, Silvia; de Candia, Antonio

    2013-01-01

    We model spontaneous cortical activity with a network of coupled spiking units, in which multiple spatio-temporal patterns are stored as dynamical attractors. We introduce an order parameter, which measures the overlap (similarity) between the activity of the network and the stored patterns. We find that, depending on the excitability of the network, different working regimes are possible. For high excitability, the dynamical attractors are stable, and a collective activity that replays one of the stored patterns emerges spontaneously, while for low excitability, no replay is induced. Between these two regimes, there is a critical region in which the dynamical attractors are unstable, and intermittent short replays are induced by noise. At the critical spiking threshold, the order parameter goes from zero to one, and its fluctuations are maximized, as expected for a phase transition (and as observed in recent experimental results in the brain). Notably, in this critical region, the avalanche size and duration distributions follow power laws. Critical exponents are consistent with a scaling relationship observed recently in neural avalanches measurements. In conclusion, our simple model suggests that avalanche power laws in cortical spontaneous activity may be the effect of a network at the critical point between the replay and non-replay of spatio-temporal patterns.

  17. Experimental study of spatiotemporally localized surface gravity water waves.

    PubMed

    Chabchoub, A; Akhmediev, N; Hoffmann, N P

    2012-07-01

    We present experimental results on the study of spatiotemporally localized surface wave events on deep water that can be modeled using the Peregrine breather solution of the nonlinear Schrödinger equation. These are often considered as prototypes of oceanic rogue waves that can focus wave energy into a single wave packet. For small steepness values of the carrier gravity waves the Peregrine breathers are relatively wide, thus providing an excellent agreement between the theory and experimental results. For larger steepnesses the focusing leads to temporally and spatially shorter events. Nevertheless, agreement between measurements and the Peregrine breather theory remains reasonably good, with discrepancies of modulation gradients and spatiotemporal symmetries being tolerable. Lifetimes and travel distances of the spatiotemporally localized wave events determined from the experiment are in good agreement with the theory.

  18. Spiking neural network for recognizing spatiotemporal sequences of spikes

    NASA Astrophysics Data System (ADS)

    Jin, Dezhe Z.

    2004-02-01

    Sensory neurons in many brain areas spike with precise timing to stimuli with temporal structures, and encode temporally complex stimuli into spatiotemporal spikes. How the downstream neurons read out such neural code is an important unsolved problem. In this paper, we describe a decoding scheme using a spiking recurrent neural network. The network consists of excitatory neurons that form a synfire chain, and two globally inhibitory interneurons of different types that provide delayed feedforward and fast feedback inhibition, respectively. The network signals recognition of a specific spatiotemporal sequence when the last excitatory neuron down the synfire chain spikes, which happens if and only if that sequence was present in the input spike stream. The recognition scheme is invariant to variations in the intervals between input spikes within some range. The computation of the network can be mapped into that of a finite state machine. Our network provides a simple way to decode spatiotemporal spikes with diverse types of neurons.

  19. Spatiotemporal multi-resolution approximation of the Amari type neural field model.

    PubMed

    Aram, P; Freestone, D R; Dewar, M; Scerri, K; Jirsa, V; Grayden, D B; Kadirkamanathan, V

    2013-02-01

    Neural fields are spatially continuous state variables described by integro-differential equations, which are well suited to describe the spatiotemporal evolution of cortical activations on multiple scales. Here we develop a multi-resolution approximation (MRA) framework for the integro-difference equation (IDE) neural field model based on semi-orthogonal cardinal B-spline wavelets. In this way, a flexible framework is created, whereby both macroscopic and microscopic behavior of the system can be represented simultaneously. State and parameter estimation is performed using the expectation maximization (EM) algorithm. A synthetic example is provided to demonstrate the framework.

  20. Video quality assessment based on correlation between spatiotemporal motion energies

    NASA Astrophysics Data System (ADS)

    Yan, Peng; Mou, Xuanqin

    2016-09-01

    Video quality assessment (VQA) has been a hot research topic because of rapid increase of huge demand of video communications. From the earliest PSNR metric to advanced models that are perceptual aware, researchers have made great progress in this field by introducing properties of human vision system (HVS) into VQA model design. Among various algorithms that model the property of HVS perceiving motion, the spatiotemporal energy model has been validated to be high consistent with psychophysical experiments. In this paper, we take the spatiotemporal energy model into VQA model design by the following steps. 1) According to the pristine spatiotemporal energy model proposed by Adelson et al, we apply the linear filters, which are oriented in space-time and tuned in spatial frequency, to filter the reference and test videos respectively. The outputs of quadrature pairs of above filters are then squared and summed to give two measures of motion energy, which are named rightward and leftward energy responses, respectively. 2) Based on the pristine model, we calculate summation of the rightward and leftward energy responses as spatiotemporal features to represent perceptual quality information for videos, named total spatiotemporal motion energy maps. 3) The proposed FR-VQA model, named STME, is calculated with statistics based on the pixel-wise correlation between the total spatiotemporal motion energy maps of the reference and distorted videos. The STME model was validated on the LIVE VQA Database by comparing with existing FR-VQA models. Experimental results show that STME performs with excellent prediction accuracy and stays in state-of-the-art VQA models.

  1. Routes to spatiotemporal chaos in Kerr optical frequency combs

    SciTech Connect

    Coillet, Aurélien; Chembo, Yanne K.

    2014-03-15

    We investigate the various routes to spatiotemporal chaos in Kerr optical frequency combs, obtained through pumping an ultra-high Q-factor whispering-gallery mode resonator with a continuous-wave laser. The Lugiato–Lefever model is used to build bifurcation diagrams with regards to the parameters that are externally controllable, namely, the frequency and the power of the pumping laser. We show that the spatiotemporal chaos emerging from Turing patterns and solitons display distinctive dynamical features. Experimental spectra of chaotic Kerr combs are also presented for both cases, in excellent agreement with theoretical spectra.

  2. Classification with spatio-temporal interpixel class dependency contexts

    NASA Technical Reports Server (NTRS)

    Jeon, Byeungwoo; Landgrebe, David A.

    1992-01-01

    A contextual classifier which can utilize both spatial and temporal interpixel dependency contexts is investigated. After spatial and temporal neighbors are defined, a general form of maximum a posterior spatiotemporal contextual classifier is derived. This contextual classifier is simplified under several assumptions. Joint prior probabilities of the classes of each pixel and its spatial neighbors are modeled by the Gibbs random field. The classification is performed in a recursive manner to allow a computationally efficient contextual classification. Experimental results with bitemporal TM data show significant improvement of classification accuracy over noncontextual pixelwise classifiers. This spatiotemporal contextual classifier should find use in many applications of remote sensing, especially when the classification accuracy is important.

  3. Spatiotemporal focusing dynamics in plasmas at X-ray wavelength

    SciTech Connect

    Sharma, A. Tibai, Z.; Hebling, J.; Mishra, S. K.

    2014-03-15

    Using a finite curvature beam, we investigate here the spatiotemporal focusing dynamics of a laser pulse in plasmas at X-ray wavelength. We trace the dependence of curvature parameter on the focusing of laser pulse and recognize that the self-focusing in plasma is more intense for the X-ray laser pulse with curved wavefront than with flat wavefront. The simulation results demonstrate that spatiotemporal focusing dynamics in plasmas can be controlled with the appropriate choice of beam-plasma parameters to explore the high intensity effects in X-ray regime.

  4. Emergence of oscillations and spatio-temporal coherence states in a continuum-model of excitatory and inhibitory neurons.

    PubMed

    Sabatini, Silvio P; Solari, Fabio; Secchi, Luca

    2005-01-01

    A neural field model of the reaction-diffusion type for the emergence of oscillatory phenomena in visual cortices is proposed. To investigate the joint spatio-temporal oscillatory dynamics in a continuous distribution of excitatory and inhibitory neurons, the coupling among oscillators is modelled as a diffusion process, combined with non-linear point interactions. The model exhibits cooperative activation properties in both time and space, by reacting to volleys of activations at multiple cortical sites with ordered spatio-temporal oscillatory states, similar to those found in the physiological experiments on slow-wave field potentials. The possible use of the resulting spatial distributions of coherent states, as a flexible medium to establish feature association, is discussed.

  5. Resonant spatiotemporal learning in large random recurrent networks.

    PubMed

    Daucé, Emmanuel; Quoy, Mathias; Doyon, Bernard

    2002-09-01

    Taking a global analogy with the structure of perceptual biological systems, we present a system composed of two layers of real-valued sigmoidal neurons. The primary layer receives stimulating spatiotemporal signals, and the secondary layer is a fully connected random recurrent network. This secondary layer spontaneously displays complex chaotic dynamics. All connections have a constant time delay. We use for our experiments a Hebbian (covariance) learning rule. This rule slowly modifies the weights under the influence of a periodic stimulus. The effect of learning is twofold: (i) it simplifies the secondary-layer dynamics, which eventually stabilizes to a periodic orbit; and (ii) it connects the secondary layer to the primary layer, and realizes a feedback from the secondary to the primary layer. This feedback signal is added to the incoming signal, and matches it (i.e., the secondary layer performs a one-step prediction of the forthcoming stimulus). After learning, a resonant behavior can be observed: the system resonates with familiar stimuli, which activates a feedback signal. In particular, this resonance allows the recognition and retrieval of partial signals, and dynamic maintenance of the memory of past stimuli. This resonance is highly sensitive to the temporal relationships and to the periodicity of the presented stimuli. When we present stimuli which do not match in time or space, the feedback remains silent. The number of different stimuli for which resonant behavior can be learned is analyzed. As with Hopfield networks, the capacity is proportional to the size of the second, recurrent layer. Moreover, the high capacity displayed allows the implementation of our model on real-time systems interacting with their environment. Such an implementation is reported in the case of a simple behavior-based recognition task on a mobile robot. Finally, we present some functional analogies with biological systems in terms of autonomy and dynamic binding, and present

  6. Spatio-temporal coupling of EEG signals in epilepsy

    NASA Astrophysics Data System (ADS)

    Senger, Vanessa; Müller, Jens; Tetzlaff, Ronald

    2011-05-01

    Approximately 1% of the world's population suffer from epileptic seizures throughout their lives that mostly come without sign or warning. Thus, epilepsy is the most common chronical disorder of the neurological system. In the past decades, the problem of detecting a pre-seizure state in epilepsy using EEG signals has been addressed in many contributions by various authors over the past two decades. Up to now, the goal of identifying an impending epileptic seizure with sufficient specificity and reliability has not yet been achieved. Cellular Nonlinear Networks (CNN) are characterized by local couplings of dynamical systems of comparably low complexity. Thus, they are well suited for an implementation as highly parallel analogue processors. Programmable sensor-processor realizations of CNN combine high computational power comparable to tera ops of digital processors with low power consumption. An algorithm allowing an automated and reliable detection of epileptic seizure precursors would be a"huge step" towards the vision of an implantable seizure warning device that could provide information to patients and for a time/event specific treatment directly in the brain. Recent contributions have shown that modeling of brain electrical activity by solutions of Reaction-Diffusion-CNN as well as the application of a CNN predictor taking into account values of neighboring electrodes may contribute to the realization of a seizure warning device. In this paper, a CNN based predictor corresponding to a spatio-temporal filter is applied to multi channel EEG data in order to identify mutual couplings for different channels which lead to a enhanced prediction quality. Long term EEG recordings of different patients are considered. Results calculated for these recordings with inter-ictal phases as well as phases with seizures will be discussed in detail.

  7. Automatic identification of seismic swarms and other spatio-temporal clustering from catalogs

    NASA Astrophysics Data System (ADS)

    Nava, F. Alejandro; Glowacka, Ewa

    1994-06-01

    Statistical analysis of seismic catalogs usually requires identification of swarms and foreshocks-main event-aftershocks sequences-a tedious and time-consuming chore. SWaRMSHoW, a simple but versatile QBASIC program for PC, graphically displays on screen catalog epicentral activity, with optional temporal distribution scaling; identifies spatio-temporal hypocentral clusters (SwrSeq) which may be swarms or foreshocks-main event-aftershocks sequences and discriminates between these; and displays SwrSeq locations and limits, and assigns them equivalent magnitudes corresponding to those of single events having seismic energy equal to that of the whole SwrSeq. SWaRMSHoW features optional detailed disk output of swarms and clusters, including origin time, location, constituent events, equivalent magnitudes, and current parameters, that allows easy application of results. Graphic screen display includes optional maps and drawings. Operation can be completely automatic or interactive. Working parameters can be reset at any time during operation. Besides swarm and sequence identification, this program's modeling of the seismicity, scaled in both space and time, is useful for studying many aspects of spatio-temporal seismicity, such as fault activation, migration of activity, quiescence, etc.

  8. Multiple dipole modeling and localization from spatio-temporal MEG data

    SciTech Connect

    Mosher, J.C. ); Lewis, P.S. ); Leahy, R. )

    1992-06-01

    An array of biomagnetometers may be used to measure the spatio-temporal neuromagnetic field or magnetoencephalogram (MEG) produced by neural activity in the brain. A popular model for the neural activity produced in response to a given sensory stimulus is a set of current dipoles, where each dipole represents the primary current associated with the combined activation of a large number of neutrons located in a small volume of the brain. An important problem in the interpretation of MEG data from evoked response experiments is the localization of these neural current dipoles. The authors present here a linear algebraic framework for three common spatio-temporal dipole models: (i) unconstrained dipoles, (ii) dipoles with a fixed location, and (iii) dipoles with a fixed orientation and location. In all cases, they assume that the location, orientation, and magnitude of the dipoles are unknown. With a common model, they show how the parameter estimation problem may be decomposed into the estimation of the time invariant parameter using nonlinear least-squares minimization, followed by linear estimation of the associated time varying parameters. A subspace formulation is presented and used to derive a suboptimal least-squares subspace scanning method. The resulting algorithm is a special case of the well-known MUltiple SIgnal Classification (MUSIC) method, in which the solution (multiple dipole locations) is found by scanning potential locations using a simple one dipole model.

  9. Spatio-temporal topological relationships between land parcels in cadastral database

    NASA Astrophysics Data System (ADS)

    Song, W.; Zhang, F.

    2014-04-01

    There are complex spatio-temporal relationships among cadastral entities. Cadastral spatio-temporal data model should not only describe the data structure of cadastral objects, but also express cadastral spatio-temporal relationships between cadastral objects. In the past, many experts and scholars have proposed a variety of cadastral spatio-temporal data models, but few of them concentrated on the representation of spatiotemporal relationships and few of them make systematic studies on spatiotemporal relationships between cadastral objects. The studies on spatio-temporal topological relationships are not abundant. In the paper, we initially review current approaches to the studies of spatio-temporal topological relationships, and argue that spatio-temporal topological relation is the combination of temporal topology on the time dimension and spatial topology on the spatial dimension. Subsequently, we discuss and develop an integrated representation of spatio-temporal topological relationships within a 3-dimensional temporal space. In the end, based on the semantics of spatiotemporal changes between land parcels, we conclude the possible spatio-temporal topological relations between land parcels, which provide the theoretical basis for creating, updating and maintaining of land parcels in the cadastral database.

  10. Myocardial blood flow measurement with a conventional dual-head SPECT/CT with spatiotemporal iterative reconstructions - a clinical feasibility study

    PubMed Central

    Alhassen, Fares; Nguyen, Nhan; Bains, Sukhkarn; Gould, Robert G; Seo, Youngho; Bacharach, Stephen L; Song, Xiyun; Shao, Lingxiong; Gullberg, Grant T; Aparici, Carina Mari

    2014-01-01

    Cardiac single photon emission computed tomography (SPECT) cameras typically rotate too slowly around a patient to capture changes in the blood pool activity distribution and provide accurate kinetic parameters. A spatiotemporal iterative reconstruction method to overcome these limitations was investigated. Dynamic rest/stress 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) SPECT/CT was performed along with reference standard rest/stress dynamic positron emission tomography (PET/CT) 13N-NH3 in five patients. The SPECT data were reconstructed using conventional and spatiotemporal iterative reconstruction methods. The spatiotemporal reconstruction yielded improved image quality, defined here as a statistically significant (p<0.01) 50% contrast enhancement. We did not observe a statistically significant difference between the correlations of the conventional and spatiotemporal SPECT myocardial uptake K 1 values with PET K 1 values (r=0.25, 0.88, respectively) (p<0.17). These results indicate the clinical feasibility of quantitative, dynamic SPECT/CT using 99mTc-MIBI and warrant further investigation. Spatiotemporal reconstruction clearly provides an advantage over a conventional reconstruction in computing K 1. PMID:24380045

  11. Spatiotemporal Coupling of the Tongue in Amyotrophic Lateral Sclerosis

    ERIC Educational Resources Information Center

    Kuruvilla, Mili S.; Green, Jordan R.; Yunusova, Yana; Hanford, Kathy

    2012-01-01

    Purpose: The primary aim of the investigation was to identify deficits in spatiotemporal coupling between tongue regions in amyotrophic lateral sclerosis (ALS). The relations between disease-related changes in tongue movement patterns and speech intelligibility were also determined. Methods: The authors recorded word productions from 11…

  12. Spatio-temporal saliency perception via hypercomplex frequency spectral contrast.

    PubMed

    Li, Ce; Xue, Jianru; Zheng, Nanning; Lan, Xuguang; Tian, Zhiqiang

    2013-03-12

    Salient object perception is the process of sensing the salient information from the spatio-temporal visual scenes, which is a rapid pre-attention mechanism for the target location in a visual smart sensor. In recent decades, many successful models of visual saliency perception have been proposed to simulate the pre-attention behavior. Since most of the methods usually need some ad hoc parameters or high-cost preprocessing, they are difficult to rapidly detect salient object or be implemented by computing parallelism in a smart sensor. In this paper, we propose a novel spatio-temporal saliency perception method based on spatio-temporal hypercomplex spectral contrast (HSC). Firstly, the proposed HSC algorithm represent the features in the HSV (hue, saturation and value) color space and features of motion by a hypercomplex number. Secondly, the spatio-temporal salient objects are efficiently detected by hypercomplex Fourier spectral contrast in parallel. Finally, our saliency perception model also incorporates with the non-uniform sampling, which is a common phenomenon of human vision that directs visual attention to the logarithmic center of the image/video in natural scenes. The experimental results on the public saliency perception datasets demonstrate the effectiveness of the proposed approach compared to eleven state-of-the-art approaches. In addition, we extend the proposed model to moving object extraction in dynamic scenes, and the proposed algorithm is superior to the traditional algorithms.

  13. Spatio-Temporal Dynamics of Cross Polarized Wave Generation

    NASA Astrophysics Data System (ADS)

    Adams, Daniel; Squier, Jeff; Durfee, Charles

    2009-10-01

    We use time-domain Spatially and Spectrally Resolved Interferometry (SSRI) to investigate cross-polarized wave (XPW) generation in barium fluoride. We find that the XPW pulse is √3 smaller than the input in the spatiotemporal domain regardless of the input chirp. Additionally, we calculate a temporally dependent focal length resulting from the nonlinear interaction, and discuss its implications.

  14. Finding Spatio-Temporal Patterns in Large Sensor Datasets

    ERIC Educational Resources Information Center

    McGuire, Michael Patrick

    2010-01-01

    Spatial or temporal data mining tasks are performed in the context of the relevant space, defined by a spatial neighborhood, and the relevant time period, defined by a specific time interval. Furthermore, when mining large spatio-temporal datasets, interesting patterns typically emerge where the dataset is most dynamic. This dissertation is…

  15. Spatiotemporal characterization of Sclerotinia crown rot epidemics in pyrethrum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sclerotinia crown rot, caused by Sclerotinia minor and S. sclerotiorum is a disease of pyrethrum in Australia that may cause substantial decline in plant density. The spatiotemporal characteristics of the disease were quantified in 14 fields spread across three growing seasons. Fitting the binary ...

  16. Location, Location, Location: Development of Spatiotemporal Sequence Learning in Infancy

    ERIC Educational Resources Information Center

    Kirkham, Natasha Z.; Slemmer, Jonathan A.; Richardson, Daniel C.; Johnson, Scott P.

    2007-01-01

    We investigated infants' sensitivity to spatiotemporal structure. In Experiment 1, circles appeared in a statistically defined spatial pattern. At test 11-month-olds, but not 8-month-olds, looked longer at a novel spatial sequence. Experiment 2 presented different color/shape stimuli, but only the location sequence was violated during test;…

  17. Spatiotemporal Phase Synchronization in a Large Array of Convective Oscillators

    NASA Astrophysics Data System (ADS)

    Miranda, Montserrat A.; Burguete, Javier

    In a quasi-1D thermal convective system consisting of a large array of nonlinearly coupled oscillators, clustering is the way to achieve a regime of mostly antiphase synchronized oscillators. This regime is characterized by a spatiotemporal doubling of traveling modes. As the dynamics is explored beyond a spatiotemporal chaos regime with weak coupling, new interacting modes emerge through a supercritical bifurcation. In this new regime, the system exhibits coherent subsystems of antiphase synchronized oscillators, which are stationary clusters following a spatiotemporal beating phenomena. This regime is the result of a stronger coupling. We show from a phase mismatch model applied to each oscillator, that these phase coherent domains undergo a global phase instability meanwhile the interactions between oscillators become nonlocal. For each value of the control parameter we find out the time-varying topology (link matrix) from the contact interactions between oscillators. The new characteristic spatiotemporal scales are extracted from the antiphase correlations at the time intervals defined by the link matrix. The interpretation of these experimental results contributes to widen the understanding of other complex systems exhibiting similar phase chaotic dynamics in 2D and 3D.

  18. Water shortage risk assessment using spatiotemporal flow simulation

    NASA Astrophysics Data System (ADS)

    Hsieh, Hsin-I.; Su, Ming-Daw; Wu, Yii-Chen; Cheng, Ke-Sheng

    2016-12-01

    Paddy irrigation practices in Taiwan utilize complicated water conveyance networks which draw streamflows from different tributaries. Characterizing and simulating streamflow series is thus an essential task for irrigation risk assessment and planning mitigation measures. It generally involves modeling the temporal variation and spatial correlation of streamflow data at different sites. Like many other environmental variables, streamflows are asymmetric and non-Gaussian. Such properties exacerbate the difficulties in spatiotemporal modeling of streamflow data. A stochastic spatiotemporal simulation approach capable of generating non-Gaussian ten-day period streamflow data series at different sites is presented in this paper. Historical flow data from different flow stations in southern Taiwan were used to exemplify the application of the proposed model. Simulated realizations of the spatiotemporal anisotropic multivariate Pearson type III distribution were validated by comparing parameters and spatiotemporal correlation characteristics of the simulated data and the observed streamflow data. Risks of irrigation water shortage were estimated and the effect of mitigation measures was assessed using the simulated data.

  19. Cubic map algebra functions for spatio-temporal analysis

    USGS Publications Warehouse

    Mennis, J.; Viger, R.; Tomlin, C.D.

    2005-01-01

    We propose an extension of map algebra to three dimensions for spatio-temporal data handling. This approach yields a new class of map algebra functions that we call "cube functions." Whereas conventional map algebra functions operate on data layers representing two-dimensional space, cube functions operate on data cubes representing two-dimensional space over a third-dimensional period of time. We describe the prototype implementation of a spatio-temporal data structure and selected cube function versions of conventional local, focal, and zonal map algebra functions. The utility of cube functions is demonstrated through a case study analyzing the spatio-temporal variability of remotely sensed, southeastern U.S. vegetation character over various land covers and during different El Nin??o/Southern Oscillation (ENSO) phases. Like conventional map algebra, the application of cube functions may demand significant data preprocessing when integrating diverse data sets, and are subject to limitations related to data storage and algorithm performance. Solutions to these issues include extending data compression and computing strategies for calculations on very large data volumes to spatio-temporal data handling.

  20. Fast Spatio-Temporal Data Mining from Large Geophysical Datasets

    NASA Technical Reports Server (NTRS)

    Stolorz, P.; Mesrobian, E.; Muntz, R.; Santos, J. R.; Shek, E.; Yi, J.; Mechoso, C.; Farrara, J.

    1995-01-01

    Use of the UCLA CONQUEST (CONtent-based Querying in Space and Time) is reviewed for performance of automatic cyclone extraction and detection of spatio-temporal blocking conditions on MPP. CONQUEST is a data analysis environment for knowledge and data mining to aid in high-resolution modeling of climate modeling.

  1. Contrast Adaptation Implies Two Spatiotemporal Channels but Three Adapting Processes

    ERIC Educational Resources Information Center

    Langley, Keith; Bex, Peter J.

    2007-01-01

    The contrast gain control model of adaptation predicts that the effects of contrast adaptation correlate with contrast sensitivity. This article reports that the effects of high contrast spatiotemporal adaptors are maximum when adapting around 19 Hz, which is a factor of two or more greater than the peak in contrast sensitivity. To explain the…

  2. Spatiotemporal response of crystals in x-ray Bragg diffraction

    NASA Astrophysics Data System (ADS)

    Shvyd'ko, Yuri; Lindberg, Ryan

    2012-10-01

    The spatiotemporal response of crystals in x-ray Bragg diffraction resulting from excitation by an ultrashort, laterally confined x-ray pulse is studied theoretically. The theory presents an extension of the analysis in symmetric reflection geometry [R. R. Lindberg and Y. V. Shvyd’ko, Phys. Rev. ST Accel. Beams 15, 050706 (2012)PRABFM1098-440210.1103/PhysRevSTAB.15.050706] to the generic case, which includes Bragg diffraction both in reflection (Bragg) and transmission (Laue) asymmetric scattering geometries. The spatiotemporal response is presented as a product of a crystal-intrinsic plane-wave spatiotemporal response function and an envelope function defined by the crystal-independent transverse profile of the incident beam and the scattering geometry. The diffracted wave fields exhibit amplitude modulation perpendicular to the propagation direction due to both angular dispersion and the dispersion due to Bragg’s law. The characteristic measure of the spatiotemporal response is expressed in terms of a few parameters: the extinction length, crystal thickness, Bragg angle, asymmetry angle, and the speed of light. Applications to self-seeding of hard x-ray free-electron lasers are discussed, with particular emphasis on the relative advantages of using either the Bragg or Laue scattering geometries. Intensity front inclination in asymmetric diffraction can be used to make snapshots of ultrafast processes with femtosecond resolution.

  3. Supporting user-defined granularities in a spatiotemporal conceptual model

    USGS Publications Warehouse

    Khatri, V.; Ram, S.; Snodgrass, R.T.; O'Brien, G. M.

    2002-01-01

    Granularities are integral to spatial and temporal data. A large number of applications require storage of facts along with their temporal and spatial context, which needs to be expressed in terms of appropriate granularities. For many real-world applications, a single granularity in the database is insufficient. In order to support any type of spatial or temporal reasoning, the semantics related to granularities needs to be embedded in the database. Specifying granularities related to facts is an important part of conceptual database design because under-specifying the granularity can restrict an application, affect the relative ordering of events and impact the topological relationships. Closely related to granularities is indeterminacy, i.e., an occurrence time or location associated with a fact that is not known exactly. In this paper, we present an ontology for spatial granularities that is a natural analog of temporal granularities. We propose an upward-compatible, annotation-based spatiotemporal conceptual model that can comprehensively capture the semantics related to spatial and temporal granularities, and indeterminacy without requiring new spatiotemporal constructs. We specify the formal semantics of this spatiotemporal conceptual model via translation to a conventional conceptual model. To underscore the practical focus of our approach, we describe an on-going case study. We apply our approach to a hydrogeologic application at the United States Geologic Survey and demonstrate that our proposed granularity-based spatiotemporal conceptual model is straightforward to use and is comprehensive.

  4. Analysis of spatiotemporal signals: A method based on perturbation theory

    NASA Astrophysics Data System (ADS)

    Hutt, A.; Uhl, C.; Friedrich, R.

    1999-08-01

    We present a method of analyzing spatiotemporal signals with respect to its underlying dynamics. The algorithm aims at the determination of spatial modes and a criterion for the number of interacting modes. Simultaneously, a way of filtering of nonorthogonal noise is shown. The method is discussed by examples of simulated stable fixpoints and the Lorenz attractor.

  5. Spatio-temporal Laplacian pyramid coding for action recognition.

    PubMed

    Shao, Ling; Zhen, Xiantong; Tao, Dacheng; Li, Xuelong

    2014-06-01

    We present a novel descriptor, called spatio-temporal Laplacian pyramid coding (STLPC), for holistic representation of human actions. In contrast to sparse representations based on detected local interest points, STLPC regards a video sequence as a whole with spatio-temporal features directly extracted from it, which prevents the loss of information in sparse representations. Through decomposing each sequence into a set of band-pass-filtered components, the proposed pyramid model localizes features residing at different scales, and therefore is able to effectively encode the motion information of actions. To make features further invariant and resistant to distortions as well as noise, a bank of 3-D Gabor filters is applied to each level of the Laplacian pyramid, followed by max pooling within filter bands and over spatio-temporal neighborhoods. Since the convolving and pooling are performed spatio-temporally, the coding model can capture structural and motion information simultaneously and provide an informative representation of actions. The proposed method achieves superb recognition rates on the KTH, the multiview IXMAS, the challenging UCF Sports, and the newly released HMDB51 datasets. It outperforms state of the art methods showing its great potential on action recognition.

  6. Robust visual tracking with dual spatio-temporal context trackers

    NASA Astrophysics Data System (ADS)

    Sun, Shiyan; Zhang, Hong; Yuan, Ding

    2015-12-01

    Visual tracking is a challenging problem in computer vision. Recent years, significant numbers of trackers have been proposed. Among these trackers, tracking with dense spatio-temporal context has been proved to be an efficient and accurate method. Other than trackers with online trained classifier that struggle to meet the requirement of real-time tracking task, a tracker with spatio-temporal context can run at hundreds of frames per second with Fast Fourier Transform (FFT). Nevertheless, the performance of the tracker with Spatio-temporal context relies heavily on the learning rate of the context, which restricts the robustness of the tracker. In this paper, we proposed a tracking method with dual spatio-temporal context trackers that hold different learning rate during tracking. The tracker with high learning rate could track the target smoothly when the appearance of target changes, while the tracker with low learning rate could percepts the occlusion occurring and continues to track when the target starts to emerge again. To find the target among the candidates from these two trackers, we adopt Normalized Correlation Coefficient (NCC) to evaluate the confidence of each sample. Experimental results show that the proposed algorithm performs robustly against several state-of-the-art tracking methods.

  7. Mapping and spatiotemporal analysis tool for hydrological data: Spellmap

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lack of data management and analyses tools is one of the major limitations to effectively evaluate and use large datasets of high-resolution atmospheric, surface, and subsurface observations. High spatial and temporal resolution datasets better represent the spatiotemporal variability of hydrologica...

  8. Spatio-temporal variation of mood and anxiety symptom treatments in Christchurch in the context of the 2010/11 Canterbury earthquake sequence.

    PubMed

    Hogg, Daniel; Kingham, Simon; Wilson, Thomas M; Ardagh, Michael

    2016-11-01

    This article explores the spatio-temporal variation of mood and anxiety treatments in the context of a severe earthquake sequence. The aim was to examine a possible earthquake exposure effect, identify populations at risk and areas with particularly large mood and anxiety treatment rate increases or decreases in the affected Christchurch urban area. A significantly stronger increase of mood and anxiety treatments among residents in Christchurch compared to others in New Zealand have been found, as well as children and elderly identified as especially vulnerable. Spatio-temporal cluster analysis and Bayesian spatio-temporal modelling revealed little changes in mood and anxiety treatment patterns for most parts of the city, whereas areas in the less affected north and northwest showed the strongest increases in risk. This effect may be linked to inner-city mobility activity as a consequence of the earthquakes, but also different levels of community cohesion after the disaster, which merit further research.

  9. A High Performance Bayesian Computing Framework for Spatiotemporal Uncertainty Modeling

    NASA Astrophysics Data System (ADS)

    Cao, G.

    2015-12-01

    All types of spatiotemporal measurements are subject to uncertainty. With spatiotemporal data becomes increasingly involved in scientific research and decision making, it is important to appropriately model the impact of uncertainty. Quantitatively modeling spatiotemporal uncertainty, however, is a challenging problem considering the complex dependence and dataheterogeneities.State-space models provide a unifying and intuitive framework for dynamic systems modeling. In this paper, we aim to extend the conventional state-space models for uncertainty modeling in space-time contexts while accounting for spatiotemporal effects and data heterogeneities. Gaussian Markov Random Field (GMRF) models, also known as conditional autoregressive models, are arguably the most commonly used methods for modeling of spatially dependent data. GMRF models basically assume that a geo-referenced variable primarily depends on its neighborhood (Markov property), and the spatial dependence structure is described via a precision matrix. Recent study has shown that GMRFs are efficient approximation to the commonly used Gaussian fields (e.g., Kriging), and compared with Gaussian fields, GMRFs enjoy a series of appealing features, such as fast computation and easily accounting for heterogeneities in spatial data (e.g, point and areal). This paper represents each spatial dataset as a GMRF and integrates them into a state-space form to statistically model the temporal dynamics. Different types of spatial measurements (e.g., categorical, count or continuous), can be accounted for by according link functions. A fast alternative to MCMC framework, so-called Integrated Nested Laplace Approximation (INLA), was adopted for model inference.Preliminary case studies will be conducted to showcase the advantages of the described framework. In the first case, we apply the proposed method for modeling the water table elevation of Ogallala aquifer over the past decades. In the second case, we analyze the

  10. Field scale spatio-temporal soil moisture variability for trafficability and crop water availability

    NASA Astrophysics Data System (ADS)

    Carranza, Coleen; van der Ploeg, Martine; Ritsema, Coen

    2016-04-01

    Spatio-temporal patterns of soil moisture have been studied mostly for inputs in land surface models for weather and climate predictions. Remote sensing techniques for estimation of soil moisture have been explored because of the good spatial coverage at different scales. Current available satellite data provide surface soil moisture as microwave systems only measure soil moisture content up to 5cm soil depth. The OWAS1S project will focus on estimation of soil moisture from freely available Sentinel-1 datasets for operational water management in agricultural areas. As part of the project, it is essential to develop spatio-temporal methods to estimate root zone soil moisture from surface soil moisture. This will be used for crop water availability and trafficability in selected agricultural fields in the Netherlands. A network of single capacitance sensors installed per field will provide continuous measurements of soil moisture in the study area. Ground penetrating radar will be used to measure soil moisture variability within a single field for different time periods. During wetter months, optimal conditions for traffic will be assessed using simultaneous soil strength and soil moisture measurements. Towards water deficit periods, focus is on the relation (or the lack thereof) between surface soil moisture and root zone soil moisture to determine the amount of water for crops. Spatio-temporal distribution will determine important physical controls for surface and root zone soil moisture and provide insights for root-zone soil moisture. Existing models for field scale soil-water balance and data assimilation methods (e.g. Kalman filter) will be combined to estimate root zone soil moisture. Furthermore, effects of root development on soil structure and soil hydraulic properties and subsequent effects on trafficability and crop water availability will be investigated. This research project has recently started, therefore we want to present methods and framework of

  11. The influence of spatiotemporal structure of noisy stimuli in decision making.

    PubMed

    Insabato, Andrea; Dempere-Marco, Laura; Pannunzi, Mario; Deco, Gustavo; Romo, Ranulfo

    2014-04-01

    Decision making is a process of utmost importance in our daily lives, the study of which has been receiving notable attention for decades. Nevertheless, the neural mechanisms underlying decision making are still not fully understood. Computational modeling has revealed itself as a valuable asset to address some of the fundamental questions. Biophysically plausible models, in particular, are useful in bridging the different levels of description that experimental studies provide, from the neural spiking activity recorded at the cellular level to the performance reported at the behavioral level. In this article, we have reviewed some of the recent progress made in the understanding of the neural mechanisms that underlie decision making. We have performed a critical evaluation of the available results and address, from a computational perspective, aspects of both experimentation and modeling that so far have eluded comprehension. To guide the discussion, we have selected a central theme which revolves around the following question: how does the spatiotemporal structure of sensory stimuli affect the perceptual decision-making process? This question is a timely one as several issues that still remain unresolved stem from this central theme. These include: (i) the role of spatiotemporal input fluctuations in perceptual decision making, (ii) how to extend the current results and models derived from two-alternative choice studies to scenarios with multiple competing evidences, and (iii) to establish whether different types of spatiotemporal input fluctuations affect decision-making outcomes in distinctive ways. And although we have restricted our discussion mostly to visual decisions, our main conclusions are arguably generalizable; hence, their possible extension to other sensory modalities is one of the points in our discussion.

  12. The Influence of Spatiotemporal Structure of Noisy Stimuli in Decision Making

    PubMed Central

    Deco, Gustavo; Romo, Ranulfo

    2014-01-01

    Decision making is a process of utmost importance in our daily lives, the study of which has been receiving notable attention for decades. Nevertheless, the neural mechanisms underlying decision making are still not fully understood. Computational modeling has revealed itself as a valuable asset to address some of the fundamental questions. Biophysically plausible models, in particular, are useful in bridging the different levels of description that experimental studies provide, from the neural spiking activity recorded at the cellular level to the performance reported at the behavioral level. In this article, we have reviewed some of the recent progress made in the understanding of the neural mechanisms that underlie decision making. We have performed a critical evaluation of the available results and address, from a computational perspective, aspects of both experimentation and modeling that so far have eluded comprehension. To guide the discussion, we have selected a central theme which revolves around the following question: how does the spatiotemporal structure of sensory stimuli affect the perceptual decision-making process? This question is a timely one as several issues that still remain unresolved stem from this central theme. These include: (i) the role of spatiotemporal input fluctuations in perceptual decision making, (ii) how to extend the current results and models derived from two-alternative choice studies to scenarios with multiple competing evidences, and (iii) to establish whether different types of spatiotemporal input fluctuations affect decision-making outcomes in distinctive ways. And although we have restricted our discussion mostly to visual decisions, our main conclusions are arguably generalizable; hence, their possible extension to other sensory modalities is one of the points in our discussion. PMID:24743140

  13. Spatiotemporal Analyses of Osteogenesis and Angiogenesis via Intravital Imaging in Cranial Bone Defect Repair

    PubMed Central

    Huang, Chunlan; Ness, Vincent P.; Yang, Xiaochuan; Chen, Hongli; Luo, Jiebo; Brown, Edward B; Zhang, Xinping

    2015-01-01

    Osteogenesis and angiogenesis are two integrated components in bone repair and regeneration. A deeper understanding of osteogenesis and angiogenesis has been hampered by technical difficulties of analyzing bone and neovasculature simultaneously in spatiotemporal scales and in three-dimensional formats. To overcome these barriers, a cranial defect window chamber model was established that enabled high-resolution, longitudinal, and real-time tracking of angiogenesis and bone defect healing via Multiphoton Laser Scanning Microscopy (MPLSM). By simultaneously probing new bone matrix via second harmonic generation (SHG), neovascular networks via intravenous perfusion of fluorophore, and osteoblast differentiation via 2.3kb collagen type I promoter driven GFP (Col2.3GFP), we examined the morphogenetic sequence of cranial bone defect healing and further established the spatiotemporal analyses of osteogenesis and angiogenesis coupling in repair and regeneration. We demonstrated that bone defect closure was initiated in the residual bone around the edge of the defect. The expansion and migration of osteoprogenitors into the bone defect occurred during the first 3 weeks of healing, coupled with vigorous microvessel angiogenesis at the leading edge of the defect. Subsequent bone repair was marked by matrix deposition and active vascular network remodeling within new bone. Implantation of bone marrow stromal cells (BMSCs) isolated from Col2.3GFP mice further showed that donor-dependent bone formation occurred rapidly within the first 3 weeks of implantation, in concert with early angiogenesis. The subsequent bone wound closure was largely host-dependent, associated with localized modest induction of angiogenesis. The establishment of a live imaging platform via cranial window provides a unique tool to understand osteogenesis and angiogenesis in repair and regeneration, enabling further elucidation of the spatiotemporal regulatory mechanisms of osteoprogenitor cell interactions

  14. Spatiotemporal Temperature Distribution and Cancer Cell Death in Response to Extracellular Hyperthermia Induced by Gold Nanorods

    PubMed Central

    Huang, Huang-Chiao; Rege, Kaushal; Heys, Jeffrey J.

    2010-01-01

    Plasmonic nanoparticles have shown promise in hyperthermic cancer therapy, both in vitro and in vivo. Previous reports have described hyperthermic ablation using targeted and non-targeted nanoparticles internalized by cancer cells, but most reports do not describe a theoretical analysis for determining optimal parameters. The focus of the current research was first to evaluate the spatiotemporal temperature distribution and cell death induced by extracellular hyperthermia in which gold nanorods (GNRs) were maintained in the dispersion outside human prostate cancer cells. The nanorod dispersion was irradiated with near infrared (NIR) laser and the spatiotemporal distribution of temperature was determined experimentally. This information was employed to develop and validate theoretical models of spatiotemporal temperature profiles for gold nanorod dispersions undergoing laser irradiation, and the impact of the resulting heat generation on the viability of human prostate cancer cells. A cell injury/death model was then coupled to the heat transfer model to predict spatial and temporal variations in cell death and injury. The model predictions agreed well with experimental measurements of both, temperature and cell death profiles. Finally, the model was extended to examine the impact of selective binding of gold nanorods to cancer cells compared to non-malignant cells, coupled with a small change in cell injury activation energy. The impact of these relatively minor changes results in a dramatic change in the overall cell death rate. Taken together, extracellular hyperthermia using gold nanorods is a promising strategy and tailoring the cellular binding efficacy of nanorods can result in varying therapeutic efficacies using this approach. PMID:20387828

  15. Spatio-temporal modelling of individual exposure to air pollution and its uncertainty

    NASA Astrophysics Data System (ADS)

    Gerharz, Lydia E.; Klemm, Otto; Broich, Anna V.; Pebesma, Edzer

    2013-01-01

    We developed a generic spatio-temporal model to quantify individual exposure to air pollution, using personal activity profiles derived from GPS and diaries, ambient air quality, and an indoor model. To enhance accessibility and reusability, the model approach is deployed as a web service. The model is applied to estimate personal exposure towards PM10 and PM2.5 for ten individuals in Münster, Germany. Modelled daily averages range for PM10 between 17 and 126 and between 6 and 84 μg m-3 for PM2.5. Comparison with personal monitoring data shows good agreement at temporal resolutions from 5 min to one day. Uncertainties in the model results are considerable and increase with higher exposure levels. Large deviations between modelled and measured exposure can often be explained by missing data on indoor emissions or insufficiently detailed activity diaries. The developed model allows the assessment of individual exposure with uncertainties on a high spatio-temporal resolution. By providing the methodology through a web service interface and using generic indoor parameter distributions, the model can be easily transferred to new application areas or could be provided for public use to identify hazardous exposure events.

  16. Spatiotemporal choreography of chromosome and megaplasmids in the Sinorhizobium meliloti cell cycle.

    PubMed

    Frage, Benjamin; Döhlemann, Johannes; Robledo, Marta; Lucena, Daniella; Sobetzko, Patrick; Graumann, Peter L; Becker, Anke

    2016-06-01

    A considerable share of bacterial species maintains multipartite genomes. Precise coordination of genome replication and segregation with cell growth and division is vital for proliferation of these bacteria. The α-proteobacterium Sinorhizobium meliloti possesses a tripartite genome composed of one chromosome and the megaplasmids pSymA and pSymB. Here, we investigated the spatiotemporal pattern of segregation of these S. meliloti replicons at single cell level. Duplication of chromosomal and megaplasmid origins of replication occurred spatially and temporally separated, and only once per cell cycle. Tracking of FROS (fluorescent repressor operator system)-labelled origins revealed a strict temporal order of segregation events commencing with the chromosome followed by pSymA and then by pSymB. The repA2B2C2 region derived from pSymA was sufficient to confer the spatiotemporal behaviour of this megaplasmid to a small plasmid. Altering activity of the ubiquitous prokaryotic replication initiator DnaA, either positively or negatively, resulted in an increase in replication initiation events or G1 arrest of the chromosome only. This suggests that interference with DnaA activity does not affect replication initiation control of the megaplasmids.

  17. Investigations on postural stability and spatiotemporal parameters of human gait using developed wearable smart insole.

    PubMed

    Das, Ratan; Kumar, Neelesh

    2015-01-01

    Measurement of spatiotemporal parameters of human gait is important for designing new, intelligent and efficient prosthetic and orthotic devices. The paper presents a novel application of smart insole for measuring force generated at various pressure points during dynamic gait on a human foot. Besides recording and analysing the spatiotemporal parameters during stance phase, the developed sensor is also used for development of active orthotic devices. Data from the sensors is analysed in LabVIEW software for detection of plantar force and temporal gait parameters. The smart instrumentation allows processing, display and storage of gait parameters and gait events in real time. Variations of pressure pattern reported by gait experiments can also be used in identifying an accidental fall. This information will be used as a feedback signal for controlling the motion of an indigenously developed gait assistive device, i.e. an active orthotic device. Pressure at the heel and great toe points is higher than the metatarsal heads during dynamic walk. It is higher at the heel and metatarsals points than the toe point during standing position.

  18. Control of cell interaction using quasi-monochromatic light with varying spatiotemporal coherence

    NASA Astrophysics Data System (ADS)

    Budagovsky, A. V.; Maslova, M. V.; Budagovskaya, O. N.; Budagovsky, I. A.

    2017-02-01

    By the example of plants, fungi and bacteria, we consider the possibility of controlling the interaction of cells, being in competitive, antagonistic, or parasitic relations. For this aim we used short-time irradiation (a few seconds or minutes) with the red (633 nm) quasi-monochromatic light having different spatiotemporal coherence. It is shown that the functional activity is mostly increased in the cells whose size does not exceed the coherence length and the correlation radius of the light field. Thus, in the case of cells essentially differing in size, it is possible to increase the activity of smaller cells, avoiding the stimulation of larger ones. For example, the radiation having relatively low coherence (Lcoh, rcor <= 10 μm) facilitates mainly the damage of large-size plant cells by pathogen fungi, while the exposure to light with less statistical regularity (Lcoh = 4 μm, rcor = 5 μm) inhibits the growth of the Fusarium microcera fungus, infected by the bacterium of the Pseudomonas species. The quasi-monochromatic radiation with sufficiently high spatiotemporal coherence stimulated all interacting species (bacteria, fungi, plants). In the considered biocenosis, the equilibrium was shifted towards the favour of organisms having the highest rate of cell division or the ones better using their adaptation potential.

  19. Spatiotemporal dynamics of lipid signaling: protein kinase C as a paradigm

    PubMed Central

    Gallegos, Lisa L.; Newton, Alexandra C.

    2009-01-01

    Summary The lipid second messenger diacylglycerol (DAG) acutely controls the rate, amplitude, duration, and location of protein kinase C (PKC) activity in the cell. There are three classes of PKC isozymes and, of these, the conventional and novel isozymes are acutely controlled by DAG. The kinetics of DAG production at various intracellular membranes, the intrinsic affinity of specific isoforms for DAG-containing membranes, the coordinated use of additional membrane-binding modules, the intramolecular regulation of DAG sensitivity, and the competition from other DAG-responsive proteins together result in a unique, context-dependent activation signature for each isoform. This review focuses on the spatiotemporal dynamics of PKC activation and how it is controlled by lipid second messengers. PMID:18720411

  20. Under lock and key: Spatiotemporal regulation of WASP family proteins coordinates separate dynamic cellular processes

    PubMed Central

    Burianek, Lauren E.; Soderling, Scott H.

    2013-01-01

    WASP family proteins are nucleation promoting factors that bind to and activate the Arp2/3 complex in order to stimulate nucleation of branched actin filaments. The WASP family consists of WASP, N-WASP, WAVE1-3, WASH, and the novel family members WHAMM and JMY. Each of the family members contains a C-terminus responsible for their nucleation promoting activity and unique N-termini that allow for them to be regulated in a spatiotemporal manner. Upon activation they reorganize the cytoskeleton for different cellular functions depending on their subcellular localization and regulatory protein interactions. Emerging evidence indicates that WASH, WHAMM, and JMY have functions that require the coordination of both actin polymerization and microtubule dynamics. Here, we review the mechanisms of regulation for each family member and their associated in vivo functions including cell migration, vesicle trafficking, and neuronal development. PMID:23291261

  1. The Critical Role of Golgi Cells in Regulating Spatio-Temporal Integration and Plasticity at the Cerebellum Input Stage

    PubMed Central

    D'Angelo, Egidio

    2008-01-01

    The discovery of the Golgi cell is bound to the foundation of the Neuron Doctrine. Recently, the excitable mechanisms of this inhibitory interneuron have been investigated with modern experimental and computational techniques raising renewed interest for the implications it might have for cerebellar circuit functions. Golgi cells are pacemakers with preferential response frequency and phase-reset in the theta-frequency band and can therefore impose specific temporal dynamics to granule cell responses. Moreover, through their connectivity, Golgi cells determine the spatio-temporal organization of cerebellar activity. Finally, Golgi cells, by controlling granule cell depolarization and NMDA channel unblock, regulate the induction of long-term synaptic plasticity at the mossy fiber – granule cell synapse. Thus, the Golgi cells can exert an extensive control on spatio-temporal signal organization and information storage in the granular layer playing a critical role for cerebellar computation. PMID:18982105

  2. Effective and efficient analysis of spatio-temporal data

    NASA Astrophysics Data System (ADS)

    Zhang, Zhongnan

    Spatio-temporal data mining, i.e., mining knowledge from large amount of spatio-temporal data, is a highly demanding field because huge amounts of spatio-temporal data have been collected in various applications, ranging from remote sensing, to geographical information systems (GIS), computer cartography, environmental assessment and planning, etc. The collection data far exceeded human's ability to analyze which make it crucial to develop analysis tools. Recent studies on data mining have extended to the scope of data mining from relational and transactional datasets to spatial and temporal datasets. Among the various forms of spatio-temporal data, remote sensing images play an important role, due to the growing wide-spreading of outer space satellites. In this dissertation, we proposed two approaches to analyze the remote sensing data. The first one is about applying association rules mining onto images processing. Each image was divided into a number of image blocks. We built a spatial relationship for these blocks during the dividing process. This made a large number of images into a spatio-temporal dataset since each image was shot in time-series. The second one implemented co-occurrence patterns discovery from these images. The generated patterns represent subsets of spatial features that are located together in space and time. A weather analysis is composed of individual analysis of several meteorological variables. These variables include temperature, pressure, dew point, wind, clouds, visibility and so on. Local-scale models provide detailed analysis and forecasts of meteorological phenomena ranging from a few kilometers to about 100 kilometers in size. When some of above meteorological variables have some special change tendency, some kind of severe weather will happen in most cases. Using the discovery of association rules, we found that some special meteorological variables' changing has tight relation with some severe weather situation that will happen

  3. Spatiotemporal monitoring of soil salinization in irrigated Tadla Plain (Morocco) using satellite spectral indices

    NASA Astrophysics Data System (ADS)

    El Harti, Abderrazak; Lhissou, Rachid; Chokmani, Karem; Ouzemou, Jamal-eddine; Hassouna, Mohamed; Bachaoui, El Mostafa; El Ghmari, Abderrahmene

    2016-08-01

    Soil salinization is major environmental issue in irrigated agricultural production. Conventional methods for salinization monitoring are time and money consuming and limited by the high spatiotemporal variability of this phenomenon. This work aims to propose a spatiotemporal monitoring method of soil salinization in the Tadla plain in central Morocco using spectral indices derived from Thematic Mapper (TM) and Operational Land Imager (OLI) data. Six Landsat TM/OLI satellite images acquired during 13 years period (2000-2013) coupled with in-situ electrical conductivity (EC) measurements were used to develop the proposed method. After radiometric and atmospheric correction of TM/OLI images, a new soil salinity index (OLI-SI) is proposed for soil EC estimation. Validation shows that this index allowed a satisfactory EC estimation in the Tadla irrigated perimeter with coefficient of determination R2 varying from 0.55 to 0.77 and a Root Mean Square Error (RMSE) ranging between 1.02 dS/m and 2.35 dS/m. The times-series of salinity maps produced over the Tadla plain using the proposed method show that salinity is decreasing in intensity and progressively increasing in spatial extent, over the 2000-2013 period. This trend resulted in a decrease in agricultural activities in the southwestern part of the perimeter, located in the hydraulic downstream.

  4. Spatiotemporal dynamics and correlation networks of bacterial and fungal communities in a membrane bioreactor.

    PubMed

    Jeong, So-Yeon; Yi, Taewoo; Lee, Chung-Hak; Kim, Tae Gwan

    2016-11-15

    To systematically study biofilm communities responsible for biofouling in membrane bioreactors (MBRs), we characterized the spatiotemporal dynamics of bacterial and fungal biofilm communities, and their networks, in a pilot-scale flat-sheet MBR treating actual municipal wastewater. Activated sludge (AS) and membrane samples were collected on days 4 and 8. The membranes were cut into 18 tiles, and bacterial and fungal communities were analyzed using next generation sequencing. Nonmetric multidimensional scaling (NMDS) plots revealed significant temporal variations in bacterial and fungal biofilm communities due to changes in the abundances of a few dominant members. Although the experimental conditions and inoculum species pools remained constant, variogram plots of bacterial and fungal communities revealed decay in local community similarity with geographic distance at each sampling time. Variogram modeling (exponential rise to maximum, R(2) ≥ 0.79) revealed that decay patterns of both communities were different between days 4 and 8. In addition, networks of bacteria or fungi alone were distinct in network composition between days 4 and 8. The day-8 networks were more compact and clustered than those of the earlier time point. Bacteria-fungi networks show that the number of inter-domain associations decreased from 113 to 40 with time, confirming that membrane biofilm is a complex consortium of bacteria and fungi. Spatiotemporal succession in biofilm communities may be common on MBR membranes, resulting from different geographic distributions of initial microbial populations and their priority effects.

  5. Spatiotemporal analysis of the appearance of gamma-band Microstates in resting state MEG.

    PubMed

    Kelsey, Matthew; Prior, Fred W; Larson-Prior, Linda J

    2015-01-01

    Spatiotemporal analysis of EEG signal has revealed a rich set of methods to quantify neuronal activity using spatially global topographic templates, called Microstates. These methods complement more traditional spectral analysis, which uses band limited source data to determine defining differences in band power and peak characteristics. The high sampling rate and increased resistance to high frequency noise of MEG data offers an opportunity to explore the utility of spatiotemporal analysis over a wider spectrum than in EEG. In this work, we explore the utility of representing band limited MEG source data using established microstate techniques, especially in gamma frequency bands - a range yet unexplored using these techniques. We develop methods for gauging the goodness-of-fit achieved by resultant microstate templates and demonstrate sensor-level dispersion characteristics across wide-band signals as well as across signals filtered by canonical bands. These analyses reveal that, while high-frequency-band derived microstate templates are visually lawful, they fail to exhibit important explained variance and dispersion characteristics present in low- and full-band data necessary to meet the requirements of a microstate model.

  6. Adaptive Local Spatiotemporal Features from RGB-D Data for One-Shot Learning Gesture Recognition.

    PubMed

    Lin, Jia; Ruan, Xiaogang; Yu, Naigong; Yang, Yee-Hong

    2016-12-17

    Noise and constant empirical motion constraints affect the extraction of distinctive spatiotemporal features from one or a few samples per gesture class. To tackle these problems, an adaptive local spatiotemporal feature (ALSTF) using fused RGB-D data is proposed. First, motion regions of interest (MRoIs) are adaptively extracted using grayscale and depth velocity variance information to greatly reduce the impact of noise. Then, corners are used as keypoints if their depth, and velocities of grayscale and of depth meet several adaptive local constraints in each MRoI. With further filtering of noise, an accurate and sufficient number of keypoints is obtained within the desired moving body parts (MBPs). Finally, four kinds of multiple descriptors are calculated and combined in extended gradient and motion spaces to represent the appearance and motion features of gestures. The experimental results on the ChaLearn gesture, CAD-60 and MSRDailyActivity3D datasets demonstrate that the proposed feature achieves higher performance compared with published state-of-the-art approaches under the one-shot learning setting and comparable accuracy under the leave-one-out cross validation.

  7. Spatiotemporal earthquake clusters along the North Anatolian fault zone offshore Istanbul

    USGS Publications Warehouse

    Bulut, Fatih; Ellsworth, William L.; Bohnhoff, Marco; Aktar, Mustafa; Dresen, Georg

    2011-01-01

    We investigate earthquakes with similar waveforms in order to characterize spatiotemporal microseismicity clusters within the North Anatolian fault zone (NAFZ) in northwest Turkey along the transition between the 1999 ??zmit rupture zone and the Marmara Sea seismic gap. Earthquakes within distinct activity clusters are relocated with cross-correlation derived relative travel times using the double difference method. The spatiotemporal distribution of micro earthquakes within individual clusters is resolved with relative location accuracy comparable to or better than the source size. High-precision relative hypocenters define the geometry of individual fault patches, permitting a better understanding of fault kinematics and their role in local-scale seismotectonics along the region of interest. Temporal seismic sequences observed in the eastern Sea of Marmara region suggest progressive failure of mostly nonoverlapping areas on adjacent fault patches and systematic migration of microearthquakes within clusters during the progressive failure of neighboring fault patches. The temporal distributions of magnitudes as well as the number of events follow swarmlike behavior rather than a mainshock/aftershock pattern.

  8. Spatiotemporal compression for efficient storage and transmission of high-resolution electrocorticography data.

    PubMed

    Kim, Taehoon; Artan, N Sertac; Viventi, Jonathan; Chao, H Jonathan

    2012-01-01

    High-resolution Electrocorticography (HR-ECoG) has emerged as a key strategic technology for recording localized neural activity with high temporal and spatial resolution with potential applications in brain-computer interfaces (BCI), and seizure detection for epilepsy. However, HR-ECoG has 400 times the resolution of conventional ECoG, making it a challenge to process, transmit and store the HR-ECoG data. Therefore, simple and efficient compression algorithms are vital for the feasibility of implantable wireless medical devices for HR-ECoG recordings. In this paper, following the observation that HR-ECoG signals have both high spatial and temporal correlations similar to video/image signals, various compression methods suitable for video/image- compression based on motion estimation, discrete cosine transform (DCT) and discrete wavelet transform (DWT)- are investigated for compressing HR-ECoG data. We first simplify these methods to satisfy the low-power requirements for implantable devices. Then, we demonstrate that spatiotemporal compression methods produce up to 46% more data reduction on HR-ECoG data than compression methods using only spatial compression do. We further show that this data reduction can be achieved with low hardware complexity. In particular, among the methods investigated, spatiotemporal compression using DCT-based methods provide the best trade-off between hardware complexity and compression performance, and thus we conclude that DCT-based compression is a promising solution for ultralow-power implantable devices for HR-ECoG.

  9. Spatiotemporal progression of cell death in the zone of ischemia surrounding burns

    PubMed Central

    Lanier, Steven T.; McClain, Steve A.; Lin, Fubao; Singer, Adam J.; Clark, Richard A.F.

    2013-01-01

    Burns are dynamic injuries, characterized by progressive death of surrounding tissue over time. Though central to an understanding of burn injury progression, the spatiotemporal degrees and rates of cellular necrosis and apoptosis in the zone of ischemia surrounding burns are not well characterized. Using a validated porcine hot comb model, we probed periburn tissue at 1, 4, and 24 hours after injury for high mobility group box 1 (HMGB1) as a marker of necrosis and activated cleaved caspase 3 (CC3a) as a marker of apoptosis, followed by spatiotemporal morphometric analysis. We found that necrosis was the most prominent mechanism of cell death in burn injury progression, with significant progression between 1 and 4 hours post-burn. Apoptosis appeared not to play a role in early burn injury progression, but was observed in cells at the interface of necrotic and viable tissue at 24 hours post-burn. Our findings imply that intervention within the first 4 hours following injury is likely necessary to limit burn injury progression. Additionally, based on HMGB1 staining patterns, we define distinct early, intermediate and late pathological signs of cell necrosis that may facilitate delineation of causal mechanistic relationships of burn injury progression in vivo. PMID:22092800

  10. Small-Scale Spatio-Temporal Distribution of Bactrocera minax (Enderlein) (Diptera: Tephritidae) Using Probability Kriging.

    PubMed

    Wang, S Q; Zhang, H Y; Li, Z L

    2016-10-01

    Understanding spatio-temporal distribution of pest in orchards can provide important information that could be used to design monitoring schemes and establish better means for pest control. In this study, the spatial and temporal distribution of Bactrocera minax (Enderlein) (Diptera: Tephritidae) was assessed, and activity trends were evaluated by using probability kriging. Adults of B. minax were captured in two successive occurrences in a small-scale citrus orchard by using food bait traps, which were placed both inside and outside the orchard. The weekly spatial distribution of B. minax within the orchard and adjacent woods was examined using semivariogram parameters. The edge concentration was discovered during the most weeks in adult occurrence, and the population of the adults aggregated with high probability within a less-than-100-m-wide band on both of the sides of the orchard and the woods. The sequential probability kriged maps showed that the adults were estimated in the marginal zone with higher probability, especially in the early and peak stages. The feeding, ovipositing, and mating behaviors of B. minax are possible explanations for these spatio-temporal patterns. Therefore, spatial arrangement and distance to the forest edge of traps or spraying spot should be considered to enhance pest control on B. minax in small-scale orchards.

  11. Detecting spatio-temporal modes in multivariate data by entropy field decomposition

    NASA Astrophysics Data System (ADS)

    Frank, Lawrence R.; Galinsky, Vitaly L.

    2016-09-01

    A new data analysis method that addresses a general problem of detecting spatio-temporal variations in multivariate data is presented. The method utilizes two recent and complimentary general approaches to data analysis, information field theory (IFT) and entropy spectrum pathways (ESPs). Both methods reformulate and incorporate Bayesian theory, thus use prior information to uncover underlying structure of the unknown signal. Unification of ESP and IFT creates an approach that is non-Gaussian and nonlinear by construction and is found to produce unique spatio-temporal modes of signal behavior that can be ranked according to their significance, from which space-time trajectories of parameter variations can be constructed and quantified. Two brief examples of real world applications of the theory to the analysis of data bearing completely different, unrelated nature, lacking any underlying similarity, are also presented. The first example provides an analysis of resting state functional magnetic resonance imaging data that allowed us to create an efficient and accurate computational method for assessing and categorizing brain activity. The second example demonstrates the potential of the method in the application to the analysis of a strong atmospheric storm circulation system during the complicated stage of tornado development and formation using data recorded by a mobile Doppler radar. Reference implementation of the method will be made available as a part of the QUEST toolkit that is currently under development at the Center for Scientific Computation in Imaging.

  12. Transformation of spatiotemporal dynamics in the macaque vestibular system from otolith afferents to cortex

    PubMed Central

    Laurens, Jean; Liu, Sheng; Yu, Xiong-Jie; Chan, Raymond; Dickman, David; DeAngelis, Gregory C; Angelaki, Dora E

    2017-01-01

    Sensory signals undergo substantial recoding when neural activity is relayed from sensors through pre-thalamic and thalamic nuclei to cortex. To explore how temporal dynamics and directional tuning are sculpted in hierarchical vestibular circuits, we compared responses of macaque otolith afferents with neurons in the vestibular and cerebellar nuclei, as well as five cortical areas, to identical three-dimensional translational motion. We demonstrate a remarkable spatio-temporal transformation: otolith afferents carry spatially aligned cosine-tuned translational acceleration and jerk signals. In contrast, brainstem and cerebellar neurons exhibit non-linear, mixed selectivity for translational velocity, acceleration, jerk and position. Furthermore, these components often show dissimilar spatial tuning. Moderate further transformation of translation signals occurs in the cortex, such that similar spatio-temporal properties are found in multiple cortical areas. These results suggest that the first synapse represents a key processing element in vestibular pathways, robustly shaping how self-motion is represented in central vestibular circuits and cortical areas. DOI: http://dx.doi.org/10.7554/eLife.20787.001 PMID:28075326

  13. Adaptive Local Spatiotemporal Features from RGB-D Data for One-Shot Learning Gesture Recognition

    PubMed Central

    Lin, Jia; Ruan, Xiaogang; Yu, Naigong; Yang, Yee-Hong

    2016-01-01

    Noise and constant empirical motion constraints affect the extraction of distinctive spatiotemporal features from one or a few samples per gesture class. To tackle these problems, an adaptive local spatiotemporal feature (ALSTF) using fused RGB-D data is proposed. First, motion regions of interest (MRoIs) are adaptively extracted using grayscale and depth velocity variance information to greatly reduce the impact of noise. Then, corners are used as keypoints if their depth, and velocities of grayscale and of depth meet several adaptive local constraints in each MRoI. With further filtering of noise, an accurate and sufficient number of keypoints is obtained within the desired moving body parts (MBPs). Finally, four kinds of multiple descriptors are calculated and combined in extended gradient and motion spaces to represent the appearance and motion features of gestures. The experimental results on the ChaLearn gesture, CAD-60 and MSRDailyActivity3D datasets demonstrate that the proposed feature achieves higher performance compared with published state-of-the-art approaches under the one-shot learning setting and comparable accuracy under the leave-one-out cross validation. PMID:27999337

  14. Spatiotemporal Mapping of Interictal Spike Propagation: A Novel Methodology Applied to Pediatric Intracranial EEG Recordings.

    PubMed

    Tomlinson, Samuel B; Bermudez, Camilo; Conley, Chiara; Brown, Merritt W; Porter, Brenda E; Marsh, Eric D

    2016-01-01

    Synchronized cortical activity is implicated in both normative cognitive functioning and many neurologic disorders. For epilepsy patients with intractable seizures, irregular synchronization within the epileptogenic zone (EZ) is believed to provide the network substrate through which seizures initiate and propagate. Mapping the EZ prior to epilepsy surgery is critical for detecting seizure networks in order to achieve postsurgical seizure control. However, automated techniques for characterizing epileptic networks have yet to gain traction in the clinical setting. Recent advances in signal processing and spike detection have made it possible to examine the spatiotemporal propagation of interictal spike discharges across the epileptic cortex. In this study, we present a novel methodology for detecting, extracting, and visualizing spike propagation and demonstrate its potential utility as a biomarker for the EZ. Eighteen presurgical intracranial EEG recordings were obtained from pediatric patients ultimately experiencing favorable (i.e., seizure-free, n = 9) or unfavorable (i.e., seizure-persistent, n = 9) surgical outcomes. Novel algorithms were applied to extract multichannel spike discharges and visualize their spatiotemporal propagation. Quantitative analysis of spike propagation was performed using trajectory clustering and spatial autocorrelation techniques. Comparison of interictal propagation patterns revealed an increase in trajectory organization (i.e., spatial autocorrelation) among Sz-Free patients compared with Sz-Persist patients. The pathophysiological basis and clinical implications of these findings are considered.

  15. Spatiotemporal Mapping of Interictal Spike Propagation: A Novel Methodology Applied to Pediatric Intracranial EEG Recordings

    PubMed Central

    Tomlinson, Samuel B.; Bermudez, Camilo; Conley, Chiara; Brown, Merritt W.; Porter, Brenda E.; Marsh, Eric D.

    2016-01-01

    Synchronized cortical activity is implicated in both normative cognitive functioning and many neurologic disorders. For epilepsy patients with intractable seizures, irregular synchronization within the epileptogenic zone (EZ) is believed to provide the network substrate through which seizures initiate and propagate. Mapping the EZ prior to epilepsy surgery is critical for detecting seizure networks in order to achieve postsurgical seizure control. However, automated techniques for characterizing epileptic networks have yet to gain traction in the clinical setting. Recent advances in signal processing and spike detection have made it possible to examine the spatiotemporal propagation of interictal spike discharges across the epileptic cortex. In this study, we present a novel methodology for detecting, extracting, and visualizing spike propagation and demonstrate its potential utility as a biomarker for the EZ. Eighteen presurgical intracranial EEG recordings were obtained from pediatric patients ultimately experiencing favorable (i.e., seizure-free, n = 9) or unfavorable (i.e., seizure-persistent, n = 9) surgical outcomes. Novel algorithms were applied to extract multichannel spike discharges and visualize their spatiotemporal propagation. Quantitative analysis of spike propagation was performed using trajectory clustering and spatial autocorrelation techniques. Comparison of interictal propagation patterns revealed an increase in trajectory organization (i.e., spatial autocorrelation) among Sz-Free patients compared with Sz-Persist patients. The pathophysiological basis and clinical implications of these findings are considered. PMID:28066315

  16. Whole heart modeling - Spatiotemporal dynamics of electrical wave conduction and propagation.

    PubMed

    Hui Yang; Yun Chen; Leonelli, Fabio M

    2016-08-01

    Cardiac electrical activities are varying in both space and time. Human heart consists of a fractal network of muscle cells, Purkinje fibers, arteries and veins. Whole-heart modeling of electrical wave conduction and propagation involves a greater level of complexity. Our previous work developed a computer model of the anatomically realistic heart and simulated the electrical conduction with the use of cellular automata. However, simplistic assumptions and rules limit its ability to provide an accurate approximation of real-world dynamics on the complex heart surface, due to sensitive dependence of nonlinear dynamical systems on initial conditions. In this paper, we propose new reaction-diffusion methods and pattern recognition tools to simulate and model spatiotemporal dynamics of electrical wave conduction and propagation on the complex heart surface, which include (i) whole heart model; (ii) 2D isometric graphing of 3D heart geometry; (iii) reaction-diffusion modeling of electrical waves in 2D graph, and (iv) spatiotemporal pattern recognition. Experimental results show that the proposed numerical solution has strong potentials to model the space-time dynamics of electrical wave conduction in the whole heart, thereby achieving a better understanding of disease-altered cardiac mechanisms.

  17. Spatio-temporal representativeness of euphotic depth in situ sampling in transitional coastal waters

    NASA Astrophysics Data System (ADS)

    Luhtala, Hanna; Tolvanen, Harri

    2016-06-01

    In dynamic coastal waters, the representativeness of spot sampling is limited to the measurement time and place due to local heterogeneity and irregular water property fluctuations. We assessed the representativeness of in situ sampling by analysing spot-sampled depth profiles of photosynthetically active radiation (PAR) in dynamic coastal archipelago waters in the south-western Finnish coast of the Baltic Sea. First, we assessed the role of spatio-temporality within the underwater light dynamics. As a part of this approach, an anomaly detection procedure was tested on a dataset including a large archipelago area and extensive temporal coverage throughout the ice-free season. The results suggest that euphotic depth variability should be treated as a spatio-temporal process rather than considering spatial and temporal dimensions separately. Second, we assessed the representativeness of spot sampling through statistical analysis of comparative data from spatially denser sampling on three test sites on two optically different occasions. The datasets revealed variability in different dimensions and scales. The suitability of a dataset to reveal wanted phenomena can usually be improved by careful planning and by clearly defining the data sampling objectives beforehand. Nonetheless, conducting a sufficient in situ sampling in dynamic coastal area is still challenging: detecting the general patterns at all the relevant dimensions is complicated by the randomness effect, which reduces the reliability of spot samples on a more detailed scale. Our results indicate that good representativeness of a euphotic depth sampling location is not a stable feature in a highly dynamic environment.

  18. Sevoflurane Alters Spatiotemporal Functional Connectivity Motifs That Link Resting-State Networks during Wakefulness

    PubMed Central

    Kafashan, MohammadMehdi; Ching, ShiNung; Palanca, Ben J. A.

    2016-01-01

    Background: The spatiotemporal patterns of correlated neural activity during the transition from wakefulness to general anesthesia have not been fully characterized. Correlation analysis of blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI) allows segmentation of the brain into resting-state networks (RSNs), with functional connectivity referring to the covarying activity that suggests shared functional specialization. We quantified the persistence of these correlations following the induction of general anesthesia in healthy volunteers and assessed for a dynamic nature over time. Methods: We analyzed human fMRI data acquired at 0 and 1.2% vol sevoflurane. The covariance in the correlated activity among different brain regions was calculated over time using bounded Kalman filtering. These time series were then clustered into eight orthogonal motifs using a K-means algorithm, where the structure of correlated activity throughout the brain at any time is the weighted sum of all motifs. Results: Across time scales and under anesthesia, the reorganization of interactions between RSNs is related to the strength of dynamic connections between member pairs. The covariance of correlated activity between RSNs persists compared to that linking individual member pairs of different RSNs. Conclusions: Accounting for the spatiotemporal structure of correlated BOLD signals, anesthetic-induced loss of consciousness is mainly associated with the disruption of motifs with intermediate strength within and between members of different RSNs. In contrast, motifs with higher strength of connections, predominantly with regions-pairs from within-RSN interactions, are conserved among states of wakefulness and sevoflurane general anesthesia. PMID:28082871

  19. Spatiotemporal Dynamics of Argument Retrieval and Reordering: An fMRI and EEG Study on Sentence Processing

    PubMed Central

    Meyer, Lars; Obleser, Jonas; Kiebel, Stefan J.; Friederici, Angela D.

    2012-01-01

    In sentence processing, it is still unclear how the neural language network successfully establishes argument–verb dependencies in its spatiotemporal neuronal dynamics. Previous work has suggested that the establishment of subject–verb and object–verb dependencies requires argument retrieval from working memory, and that dependency establishment in object-first sentences additionally necessitates argument reordering. We examine the spatiotemporal neuronal dynamics of the brain regions that subserve these sub-processes by crossing an argument reordering factor (i.e., subject-first versus object-first sentences) with an argument retrieval factor (i.e., short versus long argument–verb dependencies) in German. Using functional magnetic resonance imaging (fMRI), we found that reordering demands focally activate the left pars opercularis (Broca’s area), while storage and retrieval demands activated left temporo-parietal (TP) regions. In addition, when analyzing the time course of fMRI-informed equivalent current dipole sources in the EEG at the subcategorizing verb, we found that activity in the TP-region occurs relatively early (40–180 ms), followed by activity in Broca’s area (300–500 ms). These findings were matched by topographical correlation analyses of fMRI activations in EEG sensor space, showing that, in the scalp potential, TP-region activity surfaces as an early positivity and IFG activity as a later positivity in the scalp potential. These results provide fine-grained evidence for spatiotemporally separable sub-processes of argument retrieval and reordering in sentence processing. PMID:23248607

  20. Optimum spatiotemporal receptive fields for vision in dim light.

    PubMed

    Klaus, Andreas; Warrant, Eric J

    2009-04-22

    Many nocturnal insects depend on vision for daily life and have evolved different strategies to improve their visual capabilities in dim light. Neural summation of visual signals is one strategy to improve visual performance, and this is likely to be especially important for insects with apposition compound eyes. Here we develop a model to determine the optimum spatiotemporal sampling of natural scenes at gradually decreasing light levels. Image anisotropy has a strong influence on the receptive field properties predicted to be optimal at low light intensities. Spatial summation between visual channels is predicted to extend more strongly in the direction with higher correlations between the input signals. Increased spatiotemporal summation increases signal-to-noise ratio at low frequencies but sacrifices signal-to-noise ratio at higher frequencies. These results, while obtained from a model of the insect visual system, are likely to apply to visual systems in general.

  1. Ordering spatiotemporal chaos in complex thermosensitive neuron networks

    NASA Astrophysics Data System (ADS)

    Gong, Yubing; Xu, Bo; Xu, Qiang; Yang, Chuanlu; Ren, Tingqi; Hou, Zhonghuai; Xin, Houwen

    2006-04-01

    We have studied the effect of random long-range connections in chaotic thermosensitive neuron networks with each neuron being capable of exhibiting diverse bursting behaviors, and found stochastic synchronization and optimal spatiotemporal patterns. For a given coupling strength, the chaotic burst-firings of the neurons become more and more synchronized as the number of random connections (or randomness) is increased and, rather, the most pronounced spatiotemporal pattern appears for an optimal randomness. As the coupling strength is increased, the optimal randomness shifts towards a smaller strength. This result shows that random long-range connections can tame the chaos in the neural networks and make the neurons more effectively reach synchronization. Since the model studied can be used to account for hypothalamic neurons of dogfish, catfish, etc., this result may reflect the significant role of random connections in transferring biological information.

  2. Sensitivity to Spatiotemporal Percepts Predicts the Perception of Emotion

    PubMed Central

    Castro, Vanessa L.; Boone, R. Thomas

    2015-01-01

    The present studies examined how sensitivity to spatiotemporal percepts such as rhythm, angularity, configuration, and force predicts accuracy in perceiving emotion. In Study 1, participants (N = 99) completed a nonverbal test battery consisting of three nonverbal emotion perception tests and two perceptual sensitivity tasks assessing rhythm sensitivity and angularity sensitivity. Study 2 (N = 101) extended the findings of Study 1 with the addition of a fourth nonverbal test, a third configural sensitivity task, and a fourth force sensitivity task. Regression analyses across both studies revealed partial support for the association between perceptual sensitivity to spatiotemporal percepts and greater emotion perception accuracy. Results indicate that accuracy in perceiving emotions may be predicted by sensitivity to specific percepts embedded within channel- and emotion-specific displays. The significance of such research lies in the understanding of how individuals acquire emotion perception skill and the processes by which distinct features of percepts are related to the perception of emotion. PMID:26339111

  3. A semiparametric spatio-temporal model for solar irradiance data

    SciTech Connect

    Patrick, Joshua D.; Harvill, Jane L.; Hansen, Clifford W.

    2016-03-01

    Here, we evaluate semiparametric spatio-temporal models for global horizontal irradiance at high spatial and temporal resolution. These models represent the spatial domain as a lattice and are capable of predicting irradiance at lattice points, given data measured at other lattice points. Using data from a 1.2 MW PV plant located in Lanai, Hawaii, we show that a semiparametric model can be more accurate than simple interpolation between sensor locations. We investigate spatio-temporal models with separable and nonseparable covariance structures and find no evidence to support assuming a separable covariance structure. These results indicate a promising approach for modeling irradiance at high spatial resolution consistent with available ground-based measurements. Moreover, this kind of modeling may find application in design, valuation, and operation of fleets of utility-scale photovoltaic power systems.

  4. Spatiotemporal analysis of ERP data in emotional processing

    NASA Astrophysics Data System (ADS)

    Hu, Jin; Tian, Jie; Yang, Lei; Pan, Xiaohong; Liu, Jianggang

    2006-03-01

    The aim of this paper is to analyze spatiotemporal patterns of Event-related potential (ERP) in emotional processing by using fuzzy k-means clustering method to segment ERP data into microstates.108 pictures (categorized as positive, negative and neutral) were presented to 24 healthy, right-handed subjects while 128-channel EEG data were recorded. For each subject, 3 artifact-free ERPs were computed under each condition. A modified fuzzy k-mean clustering method based on shape similarity is applied to the grand mean ERPs and the statistical analysis is performed to define the significance of each segmentation map. In the results, positive and negative conditions showed different spatiotemporal patterns of ERP. The results were in accord with other emotional study by fMRI or PET.

  5. A semiparametric spatio-temporal model for solar irradiance data

    DOE PAGES

    Patrick, Joshua D.; Harvill, Jane L.; Hansen, Clifford W.

    2016-03-01

    Here, we evaluate semiparametric spatio-temporal models for global horizontal irradiance at high spatial and temporal resolution. These models represent the spatial domain as a lattice and are capable of predicting irradiance at lattice points, given data measured at other lattice points. Using data from a 1.2 MW PV plant located in Lanai, Hawaii, we show that a semiparametric model can be more accurate than simple interpolation between sensor locations. We investigate spatio-temporal models with separable and nonseparable covariance structures and find no evidence to support assuming a separable covariance structure. These results indicate a promising approach for modeling irradiance atmore » high spatial resolution consistent with available ground-based measurements. Moreover, this kind of modeling may find application in design, valuation, and operation of fleets of utility-scale photovoltaic power systems.« less

  6. Spatiotemporal optical similaritons in dual-core waveguide with an external source

    NASA Astrophysics Data System (ADS)

    Soloman Raju, Thokala

    2017-04-01

    We explore analytically and numerically the existence of exact asymptotic spatiotemporal optical self-similar light bullets to the nonlinear Schrödinger equation with gain in the presence of an external source in (3+1)-dimensions. This model appertains to the description of self-similar wave propagation through asymmetric planar dual-core waveguide (DWG) amplifiers. The asymmetric DWG is composed of two adjoining, closely spaced, upper and lower waveguides, in which the lower one acts as a passive waveguide while the upper waveguide is an active one. Due to the linear coupling between them, we can control the dynamical behaviors of the wave propagating through the passive waveguide by controlling the wave in active waveguide. We explicate the mechanism to control the dynamical behaviors of these self-similar waves for two specific cases: (i) when the gain and width are hyperbolic functions and (ii) when the gain and width are periodic functions.

  7. Low-Energy Defibrillation Failure Correction is Possible Through Nonlinear Analysis of Spatiotemporal Arrhythmia Data

    NASA Astrophysics Data System (ADS)

    Simonotto, Jennifer; Furman, Michael; Beaver, Thomas; Spano, Mark; Kavanagh, Katherine; Iden, Jason; Hu, Gang; Ditto, William

    2004-03-01

    Explanted Porcine hearts were Langendorff-perfused, administered a voltage-sensitive fluorescent dye (Di-4-ANEPPS) and illuminated with a ND:Yag laser (532 nm); the change in fluorescence resulting from electrical activity on the heart surface was recorded with an 80 x 80 pixel CCD camera at 1000 frames per second. The heart was put into fibrillation with rapid ventricular pacing and shocks were administered close to the defibrillation threshold. Defibrillation failure data was analyzed using synchronization, space-time volume plots and recurrence quantification. Preliminary spatiotemporal synchronization results reveal a short window of time ( 1 second) after defibrillation failure in which the disordered electrical activity becomes ordered; this ordered period occurs 4-5 seconds after the defibrillation shock. Recurrence analysis of a single time series confirmed these results, thus opening the avenue for dynamic defibrillators that can detect an optimal window for cardioversion.

  8. Using the structure of inhibitory networks to unravel mechanisms of spatiotemporal patterning

    PubMed Central

    Assisi, Collins; Stopfer, Mark; Bazhenov, Maxim

    2011-01-01

    Summary Neuronal networks exhibit a rich dynamical repertoire, a consequence of both the intrinsic properties of neurons and the structure of the network. It has been hypothesized that inhibitory interneurons corral principal neurons into transiently synchronous ensembles that encode sensory information and sub–serve behavior. How does the structure of the inhibitory network facilitate such spatiotemporal patterning? We established a relationship between an important structural property of a network, its colorings, and the dynamics it constrains. Using a model of the insect antennal lobe we show that our description allows the explicit identification of the groups of inhibitory interneurons that switch, during odor stimulation, between activity and quiescence in a coordinated manner determined by features of the network structure. This description optimally matches the perspective of the downstream neurons looking for synchrony in ensembles of pre–synaptic cells and allows a low–dimensional description of seemingly complex high–dimensional network activity. PMID:21262473

  9. Rationally designed fluorogenic protease reporter visualizes spatiotemporal dynamics of apoptosis in vivo

    PubMed Central

    Piggott, Beverly J.; Makhijani, Kalpana; Yu, Dan; Jan, Yuh Nung; Shu, Xiaokun

    2015-01-01

    Fluorescence resonance energy transfer-based reporters have been widely used in imaging cell signaling; however, their in vivo application has been handicapped because of poor signal. Although fluorogenic reporters overcome this problem, no such reporter of proteases has been demonstrated for in vivo imaging. Now we have redesigned an infrared fluorescent protein so that its chromophore incorporation is regulated by protease activity. Upon protease activation, the infrared fluorogenic protease reporter becomes fluorescent with no requirement of exogenous cofactor. To demonstrate biological applications, we have designed an infrared fluorogenic executioner-caspase reporter, which reveals spatiotemporal coordination between cell apoptosis and embryonic morphogenesis, as well as dynamics of apoptosis during tumorigenesis in Drosophila. The designed scaffold may be used to engineer reporters of other proteases with specific cleavage sequence. PMID:25733847

  10. Deciphering the spatio-temporal regulation of entry and progression through mitosis.

    PubMed

    Gheghiani, Lilia; Gavet, Olivier

    2014-02-01

    Mitosis has been studied since the early 1880s as a key event of the cell division cycle where remarkable changes in cellular architecture take place and ultimately lead to an equal segregation of duplicated chromosomes into two daughter cells. A detailed description of the complex and highly ordered cellular events taking place is now available. Many regulators involved in key steps including entry into mitosis, nuclear envelope breakdown, microtubule (MT) spindle formation, and chromosome attachment, as well as mitotic exit and cytokinesis, have also been identified. However, understanding the precise spatio-temporal contribution of each regulator in the cell reorganization process has been technically challenging. This review will focus on a number of recent advances in our understanding of the spatial distribution of protein activities and the temporal regulation of their activation and inactivation during entry and progression through mitosis by the use of intramolecular Förster resonance energy transfer (FRET)-based biosensors.

  11. Spatiotemporal Dynamics and Reliable Computations in Recurrent Spiking Neural Networks

    NASA Astrophysics Data System (ADS)

    Pyle, Ryan; Rosenbaum, Robert

    2017-01-01

    Randomly connected networks of excitatory and inhibitory spiking neurons provide a parsimonious model of neural variability, but are notoriously unreliable for performing computations. We show that this difficulty is overcome by incorporating the well-documented dependence of connection probability on distance. Spatially extended spiking networks exhibit symmetry-breaking bifurcations and generate spatiotemporal patterns that can be trained to perform dynamical computations under a reservoir computing framework.

  12. Spatiotemporal causal modeling for the management of Dengue Fever

    NASA Astrophysics Data System (ADS)

    Yu, Hwa-Lung; Huang, Tailin; Lee, Chieh-Han

    2015-04-01

    Increasing climatic extremes have caused growing concerns about the health effects and disease outbreaks. The association between climate variation and the occurrence of epidemic diseases play an important role on a country's public health systems. Part of the impacts are direct casualties associated with the increasing frequency and intensity of typhoons, the proliferation of disease vectors and the short-term increase of clinic visits on gastro-intestinal discomforts, diarrhea, dermatosis, or psychological trauma. Other impacts come indirectly from the influence of disasters on the ecological and socio-economic systems, including the changes of air/water quality, living environment and employment condition. Previous risk assessment studies on dengue fever focus mostly on climatic and non-climatic factors and their association with vectors' reproducing pattern. The public-health implication may appear simple. Considering the seasonal changes and regional differences, however, the causality of the impacts is full of uncertainties. Without further investigation, the underlying dengue fever risk dynamics may not be assessed accurately. The objective of this study is to develop an epistemic framework for assessing dynamic dengue fever risk across space and time. The proposed framework integrates cross-departmental data, including public-health databases, precipitation data over time and various socio-economic data. We explore public-health issues induced by typhoon through literature review and spatiotemporal analytic techniques on public health databases. From those data, we identify relevant variables and possible causal relationships, and their spatiotemporal patterns derived from our proposed spatiotemporal techniques. Eventually, we create a spatiotemporal causal network and a framework for modeling dynamic dengue fever risk.

  13. Local Spatio-Temporal Analysis in Vision Systems

    DTIC Science & Technology

    1994-07-31

    evaluation, purchase and installation of a MasPar parallel computer. 14. SUBJECT TERMS 15. NUMBER OF PAGES 30 •ic QuaLlY INSPECTED 3 16. PRICE CODE 17...called "energy" models of spatio-temporal v!ion), and also in engineering analysis of digitized images (viz: the Fast Fourier Transform , which decomposes...nonstationary image data, and (when coupled with multiband/ wavelet decompositions) for the computation of symbolic descriptions of space-varying

  14. Ultrabroadband Dispersive Radiation by Spatiotemporal Oscillation of Multimode Waves.

    PubMed

    Wright, Logan G; Wabnitz, Stefan; Christodoulides, Demetrios N; Wise, Frank W

    2015-11-27

    In nonlinear dynamical systems, qualitatively distinct phenomena occur depending continuously on the size of the bounded domain containing the system. For nonlinear waves, a multimode waveguide is a bounded three-dimensional domain, allowing observation of dynamics impossible in open settings. Here we study radiation emitted by bounded nonlinear waves: the spatiotemporal oscillations of solitons in multimode fiber generate multimode dispersive waves over an ultrabroadband spectral range. This work suggests routes to sources of coherent electromagnetic waves with unprecedented spectral range.

  15. Numerical simulation and pattern characterization of nonlinear spatiotemporal dynamics on fractal surfaces for the whole-heart modeling applications

    NASA Astrophysics Data System (ADS)

    Chen, Yun; Yang, Hui

    2016-08-01

    Engineered and natural systems often involve irregular and self-similar geometric forms, which is called fractal geometry. For instance, precision machining produces a visually flat surface, while which looks like a rough mountain in the nanometer scale under the microscope. Human heart consists of a fractal network of muscle cells, Purkinje fibers, arteries and veins. Cardiac electrical activity exhibits highly nonlinear and fractal behaviors. Although space-time dynamics occur on the fractal geometry, e.g., chemical etching on the surface of machined parts and electrical conduction in the heart, most of existing works modeled space-time dynamics (e.g., reaction, diffusion and propagation) on the Euclidean geometry (e.g., flat planes and rectangular volumes). This brings inaccurate approximation of real-world dynamics, due to sensitive dependence of nonlinear dynamical systems on initial conditions. In this paper, we developed novel methods and tools for the numerical simulation and pattern recognition of spatiotemporal dynamics on fractal surfaces of complex systems, which include (1) characterization and modeling of fractal geometry, (2) fractal-based simulation and modeling of spatiotemporal dynamics, (3) recognizing and quantifying spatiotemporal patterns. Experimental results show that the proposed methods outperform traditional modeling approaches based on the Euclidean geometry, and provide effective tools to model and characterize space-time dynamics on fractal surfaces of complex systems.

  16. Delay driven spatiotemporal chaos in single species population dynamics models.

    PubMed

    Jankovic, Masha; Petrovskii, Sergei; Banerjee, Malay

    2016-08-01

    Questions surrounding the prevalence of complex population dynamics form one of the central themes in ecology. Limit cycles and spatiotemporal chaos are examples that have been widely recognised theoretically, although their importance and applicability to natural populations remains debatable. The ecological processes underlying such dynamics are thought to be numerous, though there seems to be consent as to delayed density dependence being one of the main driving forces. Indeed, time delay is a common feature of many ecological systems and can significantly influence population dynamics. In general, time delays may arise from inter- and intra-specific trophic interactions or population structure, however in the context of single species populations they are linked to more intrinsic biological phenomena such as gestation or resource regeneration. In this paper, we consider theoretically the spatiotemporal dynamics of a single species population using two different mathematical formulations. Firstly, we revisit the diffusive logistic equation in which the per capita growth is a function of some specified delayed argument. We then modify the model by incorporating a spatial convolution which results in a biologically more viable integro-differential model. Using the combination of analytical and numerical techniques, we investigate the effect of time delay on pattern formation. In particular, we show that for sufficiently large values of time delay the system's dynamics are indicative to spatiotemporal chaos. The chaotic dynamics arising in the wake of a travelling population front can be preceded by either a plateau corresponding to dynamical stabilisation of the unstable equilibrium or by periodic oscillations.

  17. The spatiotemporal properties of visual completion measured by response classification.

    PubMed

    Gold, Jason M; Shubel, Erin

    2006-03-03

    A constant problem faced by the visual system is the identification of partly occluded objects within the visual scene. Recent experiments have demonstrated that the visual system engages in a process of visual completion, where the hidden parts of objects are filled into the visual representation. Recent experiments have also suggested that there may be a time course to this completion process. Here, we examined the spatiotemporal properties of visual completion by having observers classify figures defined by either luminance-defined or illusory contours and then correlating their decisions with externally added spatiotemporal visual noise. This "response classification" technique allowed us to derive a spatiotemporal correlation map (a "classification movie") that revealed the locations used by observers at each point in space and time during the stimulus presentation. We found that observers gradually became more influenced by noise at locations corresponding to illusory contours across the first 175 ms of stimulus presentation. Our results are consistent with the idea that there is a time course to the completion process on the order of approximately 175 ms.

  18. Spatiotemporal System Identification With Continuous Spatial Maps and Sparse Estimation.

    PubMed

    Aram, Parham; Kadirkamanathan, Visakan; Anderson, Sean R

    2015-11-01

    We present a framework for the identification of spatiotemporal linear dynamical systems. We use a state-space model representation that has the following attributes: 1) the number of spatial observation locations are decoupled from the model order; 2) the model allows for spatial heterogeneity; 3) the model representation is continuous over space; and 4) the model parameters can be identified in a simple and sparse estimation procedure. The model identification procedure we propose has four steps: 1) decomposition of the continuous spatial field using a finite set of basis functions where spatial frequency analysis is used to determine basis function width and spacing, such that the main spatial frequency contents of the underlying field can be captured; 2) initialization of states in closed form; 3) initialization of state-transition and input matrix model parameters using sparse regression-the least absolute shrinkage and selection operator method; and 4) joint state and parameter estimation using an iterative Kalman-filter/sparse-regression algorithm. To investigate the performance of the proposed algorithm we use data generated by the Kuramoto model of spatiotemporal cortical dynamics. The identification algorithm performs successfully, predicting the spatiotemporal field with high accuracy, whilst the sparse regression leads to a compact model.

  19. A Multiple Regression Approach to Normalization of Spatiotemporal Gait Features.

    PubMed

    Wahid, Ferdous; Begg, Rezaul; Lythgo, Noel; Hass, Chris J; Halgamuge, Saman; Ackland, David C

    2016-04-01

    Normalization of gait data is performed to reduce the effects of intersubject variations due to physical characteristics. This study reports a multiple regression normalization approach for spatiotemporal gait data that takes into account intersubject variations in self-selected walking speed and physical properties including age, height, body mass, and sex. Spatiotemporal gait data including stride length, cadence, stance time, double support time, and stride time were obtained from healthy subjects including 782 children, 71 adults, 29 elderly subjects, and 28 elderly Parkinson's disease (PD) patients. Data were normalized using standard dimensionless equations, a detrending method, and a multiple regression approach. After normalization using dimensionless equations and the detrending method, weak to moderate correlations between walking speed, physical properties, and spatiotemporal gait features were observed (0.01 < |r| < 0.88), whereas normalization using the multiple regression method reduced these correlations to weak values (|r| <0.29). Data normalization using dimensionless equations and detrending resulted in significant differences in stride length and double support time of PD patients; however the multiple regression approach revealed significant differences in these features as well as in cadence, stance time, and stride time. The proposed multiple regression normalization may be useful in machine learning, gait classification, and clinical evaluation of pathological gait patterns.

  20. Spatiotemporal behavior and nonlinear dynamics in a phase conjugate resonator

    NASA Technical Reports Server (NTRS)

    Liu, Siuying Raymond

    1993-01-01

    The work described can be divided into two parts. The first part is an investigation of the transient behavior and stability property of a phase conjugate resonator (PCR) below threshold. The second part is an experimental and theoretical study of the PCR's spatiotemporal dynamics above threshold. The time-dependent coupled wave equations for four-wave mixing (FWM) in a photorefractive crystal, with two distinct interaction regions caused by feedback from an ordinary mirror, was used to model the transient dynamics of a PCR below threshold. The conditions for self-oscillation were determined and the solutions were used to define the PCR's transfer function and analyze its stability. Experimental results for the buildup and decay times confirmed qualitatively the predicted behavior. Experiments were carried out above threshold to study the spatiotemporal dynamics of the PCR as a function of Pragg detuning and the resonator's Fresnel number. The existence of optical vortices in the wavefront were identified by optical interferometry. It was possible to describe the transverse dynamics and the spatiotemporal instabilities by modeling the three-dimensional-coupled wave equations in photorefractive FWM using a truncated modal expansion approach.

  1. Improved kinect-based spatiotemporal and kinematic treadmill gait assessment.

    PubMed

    Eltoukhy, Moataz; Oh, Jeonghoon; Kuenze, Christopher; Signorile, Joseph

    2017-01-01

    A cost-effective, clinician friendly gait assessment tool that can automatically track patients' anatomical landmarks can provide practitioners with important information that is useful in prescribing rehabilitative and preventive therapies. This study investigated the validity and reliability of the Microsoft Kinect v2 as a potential inexpensive gait analysis tool. Ten healthy subjects walked on a treadmill at 1.3 and 1.6m·s(-1), as spatiotemporal parameters and kinematics were extracted concurrently using the Kinect and three-dimensional motion analysis. Spatiotemporal measures included step length and width, step and stride times, vertical and mediolateral pelvis motion, and foot swing velocity. Kinematic outcomes included hip, knee, and ankle joint angles in the sagittal plane. The absolute agreement and relative consistency between the two systems were assessed using interclass correlations coefficients (ICC2,1), while reproducibility between systems was established using Lin's Concordance Correlation Coefficient (rc). Comparison of ensemble curves and associated 90% confidence intervals (CI90) of the hip, knee, and ankle joint angles were performed to investigate if the Kinect sensor could consistently and accurately assess lower extremity joint motion throughout the gait cycle. Results showed that the Kinect v2 sensor has the potential to be an effective clinical assessment tool for sagittal plane knee and hip joint kinematics, as well as some spatiotemporal temporal variables including pelvis displacement and step characteristics during the gait cycle.

  2. Spatiotemporal behavior and nonlinear dynamics in a phase conjugate resonator

    NASA Astrophysics Data System (ADS)

    Liu, Siuying Raymond

    1993-12-01

    The work described can be divided into two parts. The first part is an investigation of the transient behavior and stability property of a phase conjugate resonator (PCR) below threshold. The second part is an experimental and theoretical study of the PCR's spatiotemporal dynamics above threshold. The time-dependent coupled wave equations for four-wave mixing (FWM) in a photorefractive crystal, with two distinct interaction regions caused by feedback from an ordinary mirror, was used to model the transient dynamics of a PCR below threshold. The conditions for self-oscillation were determined and the solutions were used to define the PCR's transfer function and analyze its stability. Experimental results for the buildup and decay times confirmed qualitatively the predicted behavior. Experiments were carried out above threshold to study the spatiotemporal dynamics of the PCR as a function of Pragg detuning and the resonator's Fresnel number. The existence of optical vortices in the wavefront were identified by optical interferometry. It was possible to describe the transverse dynamics and the spatiotemporal instabilities by modeling the three-dimensional-coupled wave equations in photorefractive FWM using a truncated modal expansion approach.

  3. Spatiotemporal Distribution of Chinavia hilaris (Hemiptera: Pentatomidae) in Corn Farmscapes

    PubMed Central

    Cottrell, Ted E.; Tillman, P. Glynn

    2015-01-01

    The green stink bug, Chinavia hilaris (Say) (Hemiptera: Pentatomidae), is a pest of cotton in the southeastern United States but little is known concerning its spatiotemporal distribution in corn cropping systems. Therefore, the spatiotemporal distribution of C. hilaris in farmscapes, when corn was adjacent to cotton, peanut, or both, was examined weekly. The spatial patterns of C. hilaris counts were analyzed using Spatial Analysis by Distance Indices methodology. Interpolated maps of C. hilaris density were used to visualize abundance and distribution of C. hilaris in crops in corn–peanut–cotton farmscapes. This stink bug was detected in six of seven corn–cotton farmscapes, four of six corn–peanut farmscapes, and in both corn–peanut–cotton farmscapes. The frequency of C. hilaris in cotton (89.47%) was significantly higher than in peanut (7.02%) or corn (3.51%). This stink bug fed on noncrop hosts that grew in field borders adjacent to crops. The spatial distribution of C. hilaris in crops and the capture of C. hilaris adults and nymphs in pheromone-baited traps near noncrop hosts indicated that these hosts were sources of this stink bug dispersing into crops, primarily cotton. Significant aggregated spatial distributions were detected in cotton on some dates within corn–peanut–cotton farmscapes. Maps of local clustering indices depicted small patches of C. hilaris in cotton or cotton–sorghum at the peanut–cotton interface. Factors affecting the spatiotemporal dynamics of C. hilaris in corn farmscapes are discussed. PMID:25843581

  4. Boron Neutron Capture Therapy in the Treatment of Locally Recurred Head-and-Neck Cancer: Final Analysis of a Phase I/II Trial

    SciTech Connect

    Kankaanranta, Leena; Seppaelae, Tiina; Koivunoro, Hanna; Saarilahti, Kauko; Atula, Timo; Collan, Juhani; Salli, Eero; Kortesniemi, Mika; Uusi-Simola, Jouni; Vaelimaeki, Petteri; Maekitie, Antti; Seppaenen, Marko; Minn, Heikki; Revitzer, Hannu; Kouri, Mauri; Kotiluoto, Petri; Seren, Tom; Auterinen, Iiro; Savolainen, Sauli; Joensuu, Heikki

    2012-01-01

    Purpose: To investigate the efficacy and safety of boron neutron capture therapy (BNCT) in the treatment of inoperable head-and-neck cancers that recur locally after conventional photon radiation therapy. Methods and Materials: In this prospective, single-center Phase I/II study, 30 patients with inoperable, locally recurred head-and-neck cancer (29 carcinomas and 1 sarcoma) were treated with BNCT. Prior treatments consisted of surgery and conventionally fractionated photon irradiation to a cumulative dose of 50 to 98 Gy administered with or without concomitant chemotherapy. Tumor responses were assessed by use of the RECIST (Response Evaluation Criteria in Solid Tumors) and adverse effects by use of the National Cancer Institute common terminology criteria version 3.0. Intravenously administered L-boronophenylalanine-fructose (400 mg/kg) was administered as the boron carrier. Each patient was scheduled to be treated twice with BNCT. Results: Twenty-six patients received BNCT twice; four were treated once. Of the 29 evaluable patients, 22 (76%) responded to BNCT, 6 (21%) had tumor growth stabilization for 5.1 and 20.3 months, and 1 (3%) progressed. The median progression-free survival time was 7.5 months (95% confidence interval, 5.4-9.6 months). Two-year progression-free survival and overall survival were 20% and 30%, respectively, and 27% of the patients survived for 2 years without locoregional recurrence. The most common acute Grade 3 adverse effects were mucositis (54% of patients), oral pain (54%), and fatigue (32%). Three patients were diagnosed with osteoradionecrosis (each Grade 3) and one patient with soft-tissue necrosis (Grade 4). Late Grade 3 xerostomia was present in 3 of the 15 evaluable patients (20%). Conclusions: Most patients who have inoperable, locally advanced head-and-neck carcinoma that has recurred at a previously irradiated site respond to boronophenylalanine-mediated BNCT, but cancer recurrence after BNCT remains frequent. Toxicity was

  5. Spatiotemporal Signatures of Lexical–Semantic Prediction

    PubMed Central

    Lau, Ellen F.; Weber, Kirsten; Gramfort, Alexandre; Hämäläinen, Matti S.; Kuperberg, Gina R.

    2016-01-01

    Although there is broad agreement that top-down expectations can facilitate lexical–semantic processing, the mechanisms driving these effects are still unclear. In particular, while previous electroencephalography (EEG) research has demonstrated a reduction in the N400 response to words in a supportive context, it is often challenging to dissociate facilitation due to bottom-up spreading activation from facilitation due to top-down expectations. The goal of the current study was to specifically determine the cortical areas associated with facilitation due to top-down prediction, using magnetoencephalography (MEG) recordings supplemented by EEG and functional magnetic resonance imaging (fMRI) in a semantic priming paradigm. In order to modulate expectation processes while holding context constant, we manipulated the proportion of related pairs across 2 blocks (10 and 50% related). Event-related potential results demonstrated a larger N400 reduction when a related word was predicted, and MEG source localization of activity in this time-window (350–450 ms) localized the differential responses to left anterior temporal cortex. fMRI data from the same participants support the MEG localization, showing contextual facilitation in left anterior superior temporal gyrus for the high expectation block only. Together, these results provide strong evidence that facilitatory effects of lexical–semantic prediction on the electrophysiological response 350–450 ms postonset reflect modulation of activity in left anterior temporal cortex. PMID:25316341

  6. Spatio-Temporal Brain Mapping of Motion-Onset VEPs Combined with fMRI and Retinotopic Maps

    PubMed Central

    Pitzalis, Sabrina; Strappini, Francesca; De Gasperis, Marco; Bultrini, Alessandro; Di Russo, Francesco

    2012-01-01

    Neuroimaging studies have identified several motion-sensitive visual areas in the human brain, but the time course of their activation cannot be measured with these techniques. In the present study, we combined electrophysiological and neuroimaging methods (including retinotopic brain mapping) to determine the spatio-temporal profile of motion-onset visual evoked potentials for slow and fast motion stimuli and to localize its neural generators. We found that cortical activity initiates in the primary visual area (V1) for slow stimuli, peaking 100 ms after the onset of motion. Subsequently, activity in the mid-temporal motion-sensitive areas, MT+, peaked at 120 ms, followed by peaks in activity in the more dorsal area, V3A, at 160 ms and the lateral occipital complex at 180 ms. Approximately 250 ms after stimulus onset, activity fast motion stimuli was predominant in area V6 along the parieto-occipital sulcus. Finally, at 350 ms (100 ms after the motion offset) brain activity was visible again in area V1. For fast motion stimuli, the spatio-temporal brain pattern was similar, except that the first activity was detected at 70 ms in area MT+. Comparing functional magnetic resonance data for slow vs. fast motion, we found signs of slow-fast motion stimulus topography along the posterior brain in at least three cortical regions (MT+, V3A and LOR). PMID:22558222

  7. Classification of motor intent in transradial amputees using sonomyography and spatio-temporal image analysis

    NASA Astrophysics Data System (ADS)

    Hariharan, Harishwaran; Aklaghi, Nima; Baker, Clayton A.; Rangwala, Huzefa; Kosecka, Jana; Sikdar, Siddhartha

    2016-04-01

    In spite of major advances in biomechanical design of upper extremity prosthetics, these devices continue to lack intuitive control. Conventional myoelectric control strategies typically utilize electromyography (EMG) signal amplitude sensed from forearm muscles. EMG has limited specificity in resolving deep muscle activity and poor signal-to-noise ratio. We have been investigating alternative control strategies that rely on real-time ultrasound imaging that can overcome many of the limitations of EMG. In this work, we present an ultrasound image sequence classification method that utilizes spatiotemporal features to describe muscle activity and classify motor intent. Ultrasound images of the forearm muscles were obtained from able-bodied subjects and a trans-radial amputee while they attempted different hand movements. A grid-based approach is used to test the feasibility of using spatio-temporal features by classifying hand motions performed by the subjects. Using the leave-one-out cross validation on image sequences acquired from able-bodied subjects, we observe that the grid-based approach is able to discern four hand motions with 95.31% accuracy. In case of the trans-radial amputee, we are able to discern three hand motions with 80% accuracy. In a second set of experiments, we study classification accuracy by extracting spatio-temporal sub-sequences the depict activity due to the motion of local anatomical interfaces. Short time and space limited cuboidal sequences are initially extracted and assigned an optical flow behavior label, based on a response function. The image space is clustered based on the location of cuboids and features calculated from the cuboids in each cluster. Using sequences of known motions, we extract feature vectors that describe said motion. A K-nearest neighbor classifier is designed for classification experiments. Using the leave-one-out cross validation on image sequences for an amputee subject, we demonstrate that the classifier is

  8. Inverse hydrological modelling of spatio-temporal rainfall patterns

    NASA Astrophysics Data System (ADS)

    Grundmann, Jens; Hörning, Sebastian; Bárdossy, András

    2016-04-01

    Distributed hydrological models are commonly used for simulating the non-linear response of a watershed to rainfall events for addressing different hydrological properties of the landscape. Such models are driven by spatial rainfall patterns for consecutive time steps, which are normally generated from point measurements using spatial interpolation methods. However, such methods fail in reproducing the true spatio-temporal rainfall patterns especially in data scarce regions with poorly gauged catchments or for highly dynamic, small scaled rainstorms which are not well recorded by existing monitoring networks. Consequently, uncertainties are associated with poorly identified spatio-temporal rainfall distribution in distributed rainfall-runoff-modelling since the amount of rainfall received by a catchment as well as the dynamics of the runoff generation of flood waves are underestimated. For addressing these challenges a novel methodology for inverse hydrological modelling is proposed using a Markov-Chain-Monte-Carlo framework. Thereby, potential candidates of spatio-temporal rainfall patterns are generated and selected according their ability to reproduce the observed surface runoff at the catchment outlet for a given transfer function in a best way. The Methodology combines the concept of random mixing of random spatial fields with a grid-based spatial distributed rainfall runoff model. The conditional target rainfall field is obtained as a linear combination of unconditional spatial random fields. The corresponding weights of the linear combination are selected such that the spatial variability of the rainfall amounts as well as the actual observed rainfall values are reproduced. The functionality of the methodology is demonstrated on a synthetic example. Thereby, the known spatio-temporal distribution of rainfall is reproduced for a given number of point observations of rainfall and the integral catchment response at the catchment outlet for a synthetic catchment

  9. Spatio-temporal processing of words and nonwords: hemispheric laterality and acute alcohol intoxication

    PubMed Central

    Marinkovic, Ksenija; Rosen, Burke Q.; Cox, Brendan; Hagler, Donald J.

    2014-01-01

    This study examined neurofunctional correlates of reading by modulating semantic, lexical, and orthographic attributes of letter strings. It compared the spatio-temporal activity patterns elicited by real words (RW), pseudowords, orthographically regular, pronounceable nonwords (PN) that carry no meaning, and orthographically illegal, nonpronounceable nonwords (NN). A double-duty lexical decision paradigm instructed participants to detect RW while ignoring nonwords and to additionally respond to words that refer to animals (AW). Healthy social drinkers (N=22) participated in both alcohol (0.6 g/kg ethanol for men, 0.55 g/kg for women) and placebo conditions in a counterbalanced design. Whole-head MEG signals were analyzed with an anatomically-constrained MEG method. Simultaneously acquired ERPs confirm previous evidence. Spatio-temporal MEG estimates to RW and PN are consistent with the highly replicable left-lateralized ventral visual processing stream. However, the PN elicit weaker activity than other stimuli starting at ~230 ms and extending to the M400 (magnetic equivalent of N400) in the left lateral temporal area, indicating their reduced access to lexicosemantic stores. In contrast, the NN uniquely engage the right hemisphere during the M400. Increased demands on lexicosemantic access imposed by AW result in greater activity in the left temporal cortex starting at ~230 ms and persisting through the M400 and response preparation stages. Alcohol intoxication strongly attenuates early visual responses occipito-temporally overall. Subsequently, alcohol selectively affects the left prefrontal cortex as a function of orthographic and semantic dimensions, suggesting that it modulates the dynamics of the lexicosemantic processing in a top-down manner, by increasing difficulty of semantic retrieval. PMID:24565928

  10. Spatiotemporal Organization and Cross-Frequency Coupling of Sleep Spindles in Primate Cerebral Cortex

    PubMed Central

    Takeuchi, Saori; Murai, Rie; Shimazu, Hideki; Isomura, Yoshikazu; Mima, Tatsuya; Tsujimoto, Toru

    2016-01-01

    Study Objectives: The sleep spindle has been implicated in thalamic sensory gating, cortical development, and memory consolidation. These multiple functions may depend on specific spatiotemporal emergence and interactions with other spindles and other forms of brain activity. Therefore, we measured sleep spindle cortical distribution, regional heterogeneity, synchronization, and phase relationships with other electroencephalographic components in freely moving primates. Methods: Transcortical field potentials were recorded from Japanese monkeys via telemetry and were analyzed using the Hilbert-Huang transform. Results: Spindle (12–20 Hz) current sources were identified over a wide region of the frontoparietal cortex. Most spindles occurred independently in their own frequency, but some appeared concordant between cortical areas with frequency interdependence, particularly in nearby regions and bilaterally symmetrical regions. Spindles in the dorsolateral prefrontal cortex appeared around the surface-positive and depth-negative phase of transcortically recorded slow oscillations (< 1 Hz), whereas centroparietal spindles emerged around the opposite phase. The slow-oscillation phase reversed between the prefrontal and central regions. Gamma activities increased before spindle onset. Several regional heterogeneities in properties of human spindles were replicated in the monkeys, including frequency, density, and inter-cortical time lags, although their topographic patterns were different from those of humans. The phase-amplitude coupling between spindle and gamma activity was also replicated. Conclusions: Spindles in widespread cortical regions are possibly driven by independent rhythm generators, but are temporally associated to spindles in other regions and to slow and gamma oscillations by corticocortical and thalamocortical pathways. Citation: Takeuchi S, Murai R, Shimazu H, Isomura Y, Mima T, Tsujimoto T. Spatiotemporal organization and cross-frequency coupling

  11. Sniffing and spatiotemporal coding in olfaction.

    PubMed

    Scott, John W

    2006-02-01

    The act of sniffing increases the air velocity and changes the duration of airflow in the nose. It is not yet clear how these changes interact with the intrinsic timing within the olfactory bulb, but this is a matter of current research activity. An action of sniffing in generating a high velocity that alters the sorption of odorants onto the lining of the nasal cavity is expected from the established work on odorant properties and sorption in the frog nose. Recent work indicates that the receptor properties in the olfactory epithelium and olfactory bulb are correlated with the receptor gene expression zones. The responses in both the epithelium and the olfactory bulb are predictable to a considerable extent by the hydrophobicity of odorants. Furthermore, receptor expression in both rodent and salamander nose interacts with the shapes of the nasal cavity to place the receptor sensitivity to odorants in optimal places according to the aerodynamic properties of the nose.

  12. Time-space Kriging to address the spatiotemporal misalignment in the large datasets.

    PubMed

    Liang, Dong; Kumar, Naresh

    2013-06-01

    This paper presents a Bayesian hierarchical spatiotemporal method of interpolation, termed as Markov Cube Kriging (MCK). The classical Kriging methods become computationally prohibitive, especially for large datasets due to the O(n(3)) matrix decomposition. MCK offers novel and computationally efficient solutions to address spatiotemporal misalignment, mismatch in the spatiotemporal scales and missing values across space and time in large spatiotemporal datasets. MCK is flexible in that it allows for non-separable spatiotemporal structure and nonstationary covariance at the hierarchical spatiotemporal scales. Employing MCK we developed estimates of daily concentration of fine particulates matter ≤2.5 μm in aerodynamic diameter (PM2.5) at 2.5 km spatial grid for the Cleveland Metropolitan Statistical Area, 2000 to 2009. Our validation and cross-validation suggest that MCK achieved robust prediction of spatiotemporal random effects and underlying hierarchical and nonstationary spatiotemporal structure in air pollution data. MCK has important implications for environmental epidemiology and environmental sciences for exposure quantification and collocation of data from different sources, available at different spatiotemporal scales.

  13. Time-space Kriging to address the spatiotemporal misalignment in the large datasets

    PubMed Central

    Liang, Dong; Kumar, Naresh

    2013-01-01

    This paper presents a Bayesian hierarchical spatiotemporal method of interpolation, termed as Markov Cube Kriging (MCK). The classical Kriging methods become computationally prohibitive, especially for large datasets due to the O(n3) matrix decomposition. MCK offers novel and computationally efficient solutions to address spatiotemporal misalignment, mismatch in the spatiotemporal scales and missing values across space and time in large spatiotemporal datasets. MCK is flexible in that it allows for non-separable spatiotemporal structure and nonstationary covariance at the hierarchical spatiotemporal scales. Employing MCK we developed estimates of daily concentration of fine particulates matter ≤2.5 μm in aerodynamic diameter (PM2.5) at 2.5 km spatial grid for the Cleveland Metropolitan Statistical Area, 2000 to 2009. Our validation and cross-validation suggest that MCK achieved robust prediction of spatiotemporal random effects and underlying hierarchical and nonstationary spatiotemporal structure in air pollution data. MCK has important implications for environmental epidemiology and environmental sciences for exposure quantification and collocation of data from different sources, available at different spatiotemporal scales. PMID:24039539

  14. Spatiotemporal Properties of Intracellular Calcium Signaling in Osteocytic and Osteoblastic Cell Networks under Fluid Flow

    PubMed Central

    Jing, Da; Lu, X. Lucas; Luo, Erping; Sajda, Paul; Leong, Pui L; Guo, X. Edward

    2013-01-01

    Mechanical stimuli can trigger intracellular calcium (Ca2+) responses in osteocytes and osteoblasts. Successful construction of bone cell networks necessitates more elaborate and systematic analysis for the spatiotemporal properties of Ca2+ signaling in the networks. In the present study, an unsupervised algorithm based on independent component analysis (ICA) was employed to extract the Ca2+ signals of bone cells in the network. We demonstrated that the ICA-based technology could yield higher signal fidelity than the manual region of interest (ROI) method. Second, the spatiotemporal properties of Ca2+ signaling in osteocyte-like MLO-Y4 and osteoblast-like MC3T3-E1 cell networks under laminar and steady fluid flow stimulation were systematically analyzed and compared. MLO-Y4 cells exhibited much more active Ca2+ transients than MC3T3-E1 cells, evidenced by more Ca2+ peaks, less time to the 1st peak and less time between the 1st and 2nd peaks. With respect to temporal properties, MLO-Y4 cells demonstrated higher spike rate and Ca2+ oscillating frequency. The spatial intercellular synchronous activities of Ca2+ signaling in MLO-Y4 cell networks were higher than those in MC3T3-E1 cell networks and also negatively correlated with the intercellular distance, revealing faster Ca2+ wave propagation in MLO-Y4 cell networks. Our findings show that the unsupervised ICA-based technique results in more sensitive and quantitative signal extraction than traditional ROI analysis, with the potential to be widely employed in Ca2+ signaling extraction in the cell networks. The present study also revealed a dramatic spatiotemporal difference in Ca2+ signaling for osteocytic and osteoblastic cell networks in processing the mechanical stimulus. The higher intracellular Ca2+ oscillatory behaviors and intercellular coordination of MLO-Y4 cells provided further evidences that osteocytes may behave as the major mechanical sensor in bone modeling and remodeling processes. PMID:23328496

  15. Spatiotemporal Patterns of Urban Human Mobility

    NASA Astrophysics Data System (ADS)

    Hasan, Samiul; Schneider, Christian M.; Ukkusuri, Satish V.; González, Marta C.

    2013-04-01

    The modeling of human mobility is adopting new directions due to the increasing availability of big data sources from human activity. These sources enclose digital information about daily visited locations of a large number of individuals. Examples of these data include: mobile phone calls, credit card transactions, bank notes dispersal, check-ins in internet applications, among several others. In this study, we consider the data obtained from smart subway fare card transactions to characterize and model urban mobility patterns. We present a simple mobility model for predicting peoples' visited locations using the popularity of places in the city as an interaction parameter between different individuals. This ingredient is sufficient to reproduce several characteristics of the observed travel behavior such as: the number of trips between different locations in the city, the exploration of new places and the frequency of individual visits of a particular location. Moreover, we indicate the limitations of the proposed model and discuss open questions in the current state of the art statistical models of human mobility.

  16. Spatiotemporal Analysis of Multichannel EEG: CARTOOL

    PubMed Central

    Brunet, Denis; Murray, Micah M.; Michel, Christoph M.

    2011-01-01

    This paper describes methods to analyze the brain's electric fields recorded with multichannel Electroencephalogram (EEG) and demonstrates their implementation in the software CARTOOL. It focuses on the analysis of the spatial properties of these fields and on quantitative assessment of changes of field topographies across time, experimental conditions, or populations. Topographic analyses are advantageous because they are reference independents and thus render statistically unambiguous results. Neurophysiologically, differences in topography directly indicate changes in the configuration of the active neuronal sources in the brain. We describe global measures of field strength and field similarities, temporal segmentation based on topographic variations, topographic analysis in the frequency domain, topographic statistical analysis, and source imaging based on distributed inverse solutions. All analysis methods are implemented in a freely available academic software package called CARTOOL. Besides providing these analysis tools, CARTOOL is particularly designed to visualize the data and the analysis results using 3-dimensional display routines that allow rapid manipulation and animation of 3D images. CARTOOL therefore is a helpful tool for researchers as well as for clinicians to interpret multichannel EEG and evoked potentials in a global, comprehensive, and unambiguous way. PMID:21253358

  17. Spatiotemporal analysis of multichannel EEG: CARTOOL.

    PubMed

    Brunet, Denis; Murray, Micah M; Michel, Christoph M

    2011-01-01

    This paper describes methods to analyze the brain's electric fields recorded with multichannel Electroencephalogram (EEG) and demonstrates their implementation in the software CARTOOL. It focuses on the analysis of the spatial properties of these fields and on quantitative assessment of changes of field topographies across time, experimental conditions, or populations. Topographic analyses are advantageous because they are reference independents and thus render statistically unambiguous results. Neurophysiologically, differences in topography directly indicate changes in the configuration of the active neuronal sources in the brain. We describe global measures of field strength and field similarities, temporal segmentation based on topographic variations, topographic analysis in the frequency domain, topographic statistical analysis, and source imaging based on distributed inverse solutions. All analysis methods are implemented in a freely available academic software package called CARTOOL. Besides providing these analysis tools, CARTOOL is particularly designed to visualize the data and the analysis results using 3-dimensional display routines that allow rapid manipulation and animation of 3D images. CARTOOL therefore is a helpful tool for researchers as well as for clinicians to interpret multichannel EEG and evoked potentials in a global, comprehensive, and unambiguous way.

  18. Spatiotemporal dynamics of distributed synthetic genetic circuits

    NASA Astrophysics Data System (ADS)

    Kanakov, Oleg; Laptyeva, Tetyana; Tsimring, Lev; Ivanchenko, Mikhail

    2016-04-01

    We propose and study models of two distributed synthetic gene circuits, toggle-switch and oscillator, each split between two cell strains and coupled via quorum-sensing signals. The distributed toggle switch relies on mutual repression of the two strains, and oscillator is comprised of two strains, one of which acts as an activator for another that in turn acts as a repressor. Distributed toggle switch can exhibit mobile fronts, switching the system from the weaker to the stronger spatially homogeneous state. The circuit can also act as a biosensor, with the switching front dynamics determined by the properties of an external signal. Distributed oscillator system displays another biosensor functionality: oscillations emerge once a small amount of one cell strain appears amid the other, present in abundance. Distribution of synthetic gene circuits among multiple strains allows one to reduce crosstalk among different parts of the overall system and also decrease the energetic burden of the synthetic circuit per cell, which may allow for enhanced functionality and viability of engineered cells.

  19. Spatiotemporal variability in surface energy balance across tundra, snow and ice in Greenland.

    PubMed

    Lund, Magnus; Stiegler, Christian; Abermann, Jakob; Citterio, Michele; Hansen, Birger U; van As, Dirk

    2017-02-01

    The surface energy balance (SEB) is essential for understanding the coupled cryosphere-atmosphere system in the Arctic. In this study, we investigate the spatiotemporal variability in SEB across tundra, snow and ice. During the snow-free period, the main energy sink for ice sites is surface melt. For tundra, energy is used for sensible and latent heat flux and soil heat flux leading to permafrost thaw. Longer snow-free perio