Sample records for acoustics temporal patterns

  1. Syllable acoustics, temporal patterns, and call composition vary with behavioral context in Mexican free-tailed bats

    E-print Network

    Bohn, Kirsten

    Syllable acoustics, temporal patterns, and call composition vary with behavioral context in Mexican has shown that some bat species have rich vocal repertoires with diverse syllable acoustics. Few repertoire of Mexican free-tailed bats, T. brasiliensis, is presented. Syllable acoustics and temporal

  2. Syllable acoustics, temporal patterns, and call composition vary with behavioral context in Mexican free-tailed bats.

    PubMed

    Bohn, Kirsten M; Schmidt-French, Barbara; Ma, Sean T; Pollak, George D

    2008-09-01

    Recent research has shown that some bat species have rich vocal repertoires with diverse syllable acoustics. Few studies, however, have compared vocalizations across different behavioral contexts or examined the temporal emission patterns of vocalizations. In this paper, a comprehensive examination of the vocal repertoire of Mexican free-tailed bats, T. brasiliensis, is presented. Syllable acoustics and temporal emission patterns for 16 types of vocalizations including courtship song revealed three main findings. First, although in some cases syllables are unique to specific calls, other syllables are shared among different calls. Second, entire calls associated with one behavior can be embedded into more complex vocalizations used in entirely different behavioral contexts. Third, when different calls are composed of similar syllables, distinctive temporal emission patterns may facilitate call recognition. These results indicate that syllable acoustics alone do not likely provide enough information for call recognition; rather, the acoustic context and temporal emission patterns of vocalizations may affect meaning. PMID:19045674

  3. In-Situ Optical and Acoustical Measurements of the Buoyant Cyanobacterium P. Rubescens: Spatial and Temporal Distribution Patterns

    PubMed Central

    Hofmann, Hilmar; Peeters, Frank

    2013-01-01

    Optical (fluorescence) and acoustic in-situ techniques were tested in their ability to measure the spatial and temporal distribution of plankton in freshwater ecosystems with special emphasis on the harmful and buoyant cyanobacterium P. rubescens. Fluorescence was measured with the multi-spectral FluoroProbe (Moldaenke FluoroProbe, MFP) and a Seapoint Chlorophyll Fluorometer (SCF). In-situ measurements of the acoustic backscatter strength (ABS) were conducted with three different acoustic devices covering multiple acoustic frequencies (614 kHz ADCP, 2 MHz ADP, and 6 MHz ADV). The MFP provides a fast and reliable technique to measure fluorescence at different wavelengths in situ, which allows discriminating between P. rubescens and other phytoplankton species. All three acoustic devices are sensitive to P. rubescens even if other scatterers, e.g., zooplankton or suspended sediment, are present in the water column, because P. rubescens containing gas vesicles has a strong density difference and hence acoustic contrast to the ambient water and other scatterers. After calibration, the combination of optical and acoustical measurements not only allows qualitative and quantitative observation of P. rubescens, but also distinction between P. rubescens, other phytoplankton, and zooplankton. As the measuring devices can sample in situ at high rates they enable assessment of plankton distributions at high temporal (minutes) and spatial (decimeters) resolution or covering large temporal (seasonal) and spatial (basin scale) scales. PMID:24303028

  4. Temporal patterns in the acoustic signals of beaked whales at Cross Seamount.

    PubMed

    Johnston, D W; McDonald, M; Polovina, J; Domokos, R; Wiggins, S; Hildebrand, J

    2008-04-23

    Seamounts may influence the distribution of marine mammals through a combination of increased ocean mixing, enhanced local productivity and greater prey availability. To study the effects of seamounts on the presence and acoustic behaviour of cetaceans, we deployed a high-frequency acoustic recording package on the summit of Cross Seamount during April through October 2005. The most frequently detected cetacean vocalizations were echolocation sounds similar to those produced by ziphiid and mesoplodont beaked whales together with buzz-type signals consistent with prey-capture attempts. Beaked whale signals occurred almost entirely at night throughout the six-month deployment. Measurements of prey presence with a Simrad EK-60 fisheries acoustics echo sounder indicate that Cross Seamount may enhance local productivity in near-surface waters. Concentrations of micronekton were aggregated over the seamount in near-surface waters at night, and dense concentrations of nekton were detected across the surface of the summit. Our results suggest that seamounts may provide enhanced foraging opportunities for beaked whales during the night through a combination of increased productivity, vertical migrations by micronekton and local retention of prey. Furthermore, the summit of the seamount may act as a barrier against which whales concentrate prey. PMID:18252660

  5. Temporal patterns of intra- and interspecific acoustic signals differ in two closely related species of Acanthoplus (Orthoptera: Tettigoniidae: Hetrodinae).

    PubMed

    Kowalski, Kerstin; Lakes-Harlan, Reinhard

    2011-02-01

    Males of the closely related African tettigoniids Acanthoplus discoidales and Acanthoplus longipes produce a long-lasting calling song and a short disturbance sound. The temporal patterns of the sounds were analysed in respect to species differences and song type differences. The calling songs of both species consist of impulses which are separated into verses of two syllables, with fewer impulses in the first syllable. A. longipes produces more impulses in each syllable than A. discoidales and has longer verse durations, verse intervals and syllable intervals. Also, the disturbance sounds, produced after mechanical stimulation, contain distinct verses of impulses. The disturbance sound of A. longipes has a higher number of impulses per verse than that of A. discoidales. The frequency spectra of the songs in both species have similar peak frequencies (around 12.5 kHz) and both species have their greatest hearing sensitivity in the range between 5 and 10 kHz. Females of A. longipes perform phonotaxis only to songs with a species-specific temporal pattern. By contrast, females of A. discoidales react positively to calling songs of both species. PMID:21236652

  6. Writing magnetic patterns with surface acoustic waves

    SciTech Connect

    Li, Weiyang; Buford, Benjamin; Jander, Albrecht; Dhagat, Pallavi, E-mail: dhagat@eecs.oregonstate.edu [School of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331 (United States)

    2014-05-07

    A novel patterning technique that creates magnetization patterns in a continuous magnetostrictive film with surface acoustic waves is demonstrated. Patterns of 10??m wide stripes of alternating magnetization and a 3??m dot of reversed magnetization are written using standing and focusing acoustic waves, respectively. The magnetization pattern is size-tunable, erasable, and rewritable by changing the magnetic field and acoustic power. This versatility, along with its solid-state implementation (no moving parts) and electronic control, renders it as a promising technique for application in magnetic recording, magnonic signal processing, magnetic particle manipulation, and spatial magneto-optical modulation.

  7. Transduction of temporal patterns by single neurons.

    PubMed

    Hooper, S L

    1998-12-01

    As our ability to communicate by Morse code illustrates, nervous systems can produce motor outputs, and identify sensory inputs, based on temporal patterning alone. Although this ability is central to a wide range of sensory and motor tasks, the ways in which nervous systems represent temporal patterns are not well understood. I show here that individual neurons of the lobster pyloric network can integrate rhythmic patterned input over the long times (hundreds of milliseconds) characteristic of many behaviorally relevant patterns, and that their firing delays vary as a graded function of the pattern's temporal character. These neurons directly transduce temporal patterns into a neural code, and constitute a novel biological substrate for temporal pattern detection and production. The combined activities of several such neurons can encode simple rhythmic patterns, and I provide a model illustrating how this could be achieved. PMID:10196589

  8. Discovering Phonetic Coherence in Acoustic Patterns*

    E-print Network

    Discovering Phonetic Coherence in Acoustic Patterns* Catherine T. Best,t Michael Studdert signal, listeners normally report coherent phonetic patterns corresponding to the phonemes of a language that they know. What is the basis for the internal coherence of phonetic segments? On one account, listeners

  9. Mining Complex Spatio-Temporal Sequence Patterns

    Microsoft Academic Search

    Florian Verhein

    2009-01-01

    Mining sequential movement patterns describing group behaviour in potentially streaming spatio-temporal data sets is a challenging problem. Movements are typically noisy and often overlap each other. This makes a set of simple patterns difficult to interpret and sequences diffi- cult to mine. Furthermore, group behaviour is complex. Objects in a group may behave similarly for a period of time (an

  10. Spontaneous pattern formation in an acoustical resonator

    NASA Astrophysics Data System (ADS)

    Sánchez-Morcillo, V. J.

    2004-01-01

    A dynamical system of equations describing parametric sound generation (PSG) in a dispersive large aspect ratio resonator is derived. The model generalizes previously proposed descriptions of PSG by including diffraction effects and is analogous to the model used in theoretical studies of optical parametric oscillation. A linear stability analysis of the solution below the threshold of subharmonic generation reveals the existence of a pattern forming instability, which is confirmed by numerical integration. The conditions of emergence of periodic patterns in transverse space are discussed in the acoustical context.

  11. Discrimination and identification of acoustic transient patterns

    NASA Astrophysics Data System (ADS)

    Ballas, J. A.; Howard, J. H., Jr.

    1981-08-01

    The relation between the discrimination and the identification of acoustic patterns can be addressed psychophysically or cognitively. The psychophysical approach predicts a monotonic relationship between performance on the two tasks. Cognitively, the relationship may depend upon the type of structure encoded from the patterns. Structure based upon similarities in runs could enhance discrimination but degrade identification. Hierarchical structural encoding might enhance both tasks. The relationship was investigated in three dual task experiments. In one experiment, trial and error learning was used whereas in the other two, observation of positive examples was used. All three experiments indicated that discrimination was superior to identification, and that the concurrent identification task improved discrimination performance above what has been obtained in single task discrimination studies. The effects of structure in the two tasks were equivocal but implied that the type of structured encoding is important and may be influenced by the procedure used to acquire the patterns.

  12. Acoustic and temporal partitioning of cicada assemblages in city and mountain environments.

    PubMed

    Shieh, Bao-Sen; Liang, Shih-Hsiung; Chiu, Yuh-Wen

    2015-01-01

    Comparing adaptations to noisy city environments with those to natural mountain environments on the community level can provide significant insights that allow an understanding of the impact of anthropogenic noise on invertebrates that employ loud calling songs for mate attraction, especially when each species has its distinct song, as in the case of cicadas. In this study, we investigated the partitioning strategy of cicada assemblages in city and mountain environments by comparing the acoustic features and calling activity patterns of each species, recorded using automated digital recording systems. Our comparison of activity patterns of seasonal and diel calling revealed that there was no significant temporal partitioning of cicada assemblages in either environment. In addition, there was no correlation between the acoustic distance based on spectral features and temporal segregation. Heterospecific spectral overlap was low in both city and mountain environments, although city and mountain cicada assemblages were subject to significantly different levels of anthropogenic or interspecific noise. Furthermore, for the common species found in both environments, the calling activity patterns at both seasonal and diel time scales were significantly consistent across sites and across environments. We suggest that the temporal calling activity is constrained by endogenous factors for each species and is less flexible in response to external factors, such as anthropogenic noise. As a result, cicada assemblages in city environments with low species diversity do not demonstrate a more significant temporal partitioning than those in mountain environments with high species diversity. PMID:25590620

  13. Acoustic and Temporal Partitioning of Cicada Assemblages in City and Mountain Environments

    PubMed Central

    Shieh, Bao-Sen; Liang, Shih-Hsiung; Chiu, Yuh-Wen

    2015-01-01

    Comparing adaptations to noisy city environments with those to natural mountain environments on the community level can provide significant insights that allow an understanding of the impact of anthropogenic noise on invertebrates that employ loud calling songs for mate attraction, especially when each species has its distinct song, as in the case of cicadas. In this study, we investigated the partitioning strategy of cicada assemblages in city and mountain environments by comparing the acoustic features and calling activity patterns of each species, recorded using automated digital recording systems. Our comparison of activity patterns of seasonal and diel calling revealed that there was no significant temporal partitioning of cicada assemblages in either environment. In addition, there was no correlation between the acoustic distance based on spectral features and temporal segregation. Heterospecific spectral overlap was low in both city and mountain environments, although city and mountain cicada assemblages were subject to significantly different levels of anthropogenic or interspecific noise. Furthermore, for the common species found in both environments, the calling activity patterns at both seasonal and diel time scales were significantly consistent across sites and across environments. We suggest that the temporal calling activity is constrained by endogenous factors for each species and is less flexible in response to external factors, such as anthropogenic noise. As a result, cicada assemblages in city environments with low species diversity do not demonstrate a more significant temporal partitioning than those in mountain environments with high species diversity. PMID:25590620

  14. SOME TEMPORAL CHARACTERISTICS OF VISUAL PATTERN PERCEPTION

    Microsoft Academic Search

    CHARLES W. ERIKSEN; JAMES F. COLLINS

    1967-01-01

    VISUAL STIMULI WERE CONSTRUCTED SO THAT ANY GIVEN STIMULUS BY ITSELF APPEARED TO BE A RANDOM COLLECTION OF DOTS. HOWEVER, WHEN 2 CORRESPONDING STIMULI WERE SUPERIMPOSED BY MEANS OF A 2-FIELD TACHISTOSCOPE, A 3-LETTER NONSENSE SYLLABLE WAS PERCEIVED. TEMPORAL ORGANIZATION IN PERCEPTION WAS STUDIED IN EXP. I BY VARYING THE INTERVAL BETWEEN THE PRESENTATION OF THE 2 CORRESPONDING PATTERNS OVER

  15. Auditory Temporal Pattern Discrimination and Reading Ability

    ERIC Educational Resources Information Center

    McAnally, Ken I.; Castles, Anne; Bannister, Susan

    2004-01-01

    The relation between reading ability and performance on an auditory temporal pattern discrimination task was investigated in children who were either good or delayed readers. The stimuli in the primary task consisted of sequences of tones, alternating between high and low frequencies. The threshold interstimulus interval (ISI) for discrimination…

  16. A Temporal Pattern Search Algorithm for Personal History Event Visualization

    E-print Network

    Shneiderman, Ben

    focused on temporal events and their temporal patterns in a variety of domains: health care and electronic1 A Temporal Pattern Search Algorithm for Personal History Event Visualization Taowei David Wang algorithm for searching for temporal patterns of events in historical personal histories. The traditional

  17. Spatial and temporal analysis of landscape patterns

    Microsoft Academic Search

    Monica G. Turner

    1990-01-01

    A variety of ecological questions now require the study of large regions and the understanding of spatial heterogeneity. Methods\\u000a for spatial-temporal analyses are becoming increasingly important for ecological studies. A grid cell based spatial analysis\\u000a program (SPAN) is described and results of landscape pattern analysis using SPAN are presentedd. Several ecological topics\\u000a in which geographic information systems (GIS) can play

  18. Acoustic backscattering by Hawaiian lutjanid snappers. II. Broadband temporal and spectral structure

    E-print Network

    Benoit-Bird, Kelly J.

    Acoustic backscattering by Hawaiian lutjanid snappers. II. Broadband temporal and spectral The characteristics of acoustic echoes from six species of deep-dwelling up to 400 m Hawaiian Lujanid snappers were consistent within species and were easily distinguishable between species. © 2003 Acoustical Society

  19. Auditory temporal pattern learning by songbirds using maximal stimulus diversity and minimal repetition.

    PubMed

    Comins, Jordan A; Gentner, Timothy Q

    2014-09-01

    The sequential patterning of complex acoustic elements is a salient feature of bird song and other forms of vocal communication. For European starlings (Sturnus vulgaris), a songbird species, individual vocal recognition is improved when the temporal organization of song components (called motifs) follows the normal patterns of each singer. This sensitivity to natural motif sequences may underlie observations that starlings can also learn more complex, unnatural motif patterns. Alternatively, it has been proposed that the apparent acquisition of abstract motif patterning rules instead reflects idiosyncrasies of the training conditions used in prior experiments. That is, that motif patterns are learned not by recognizing differences in temporal structures between patterns, but by identifying serendipitous features (e.g., acoustical cues) in the small sets of training and testing stimuli used. Here, we investigate this possibility, by asking whether starlings can learn to discriminate between two arbitrary motif patterns, when unique examples of each pattern are presented on every trial. Our results demonstrate that abstract motif patterning rules can be acquired from trial-unique stimuli and suggest that such training leads to better pattern generalization compared with training with much smaller stimulus subsets. PMID:24526277

  20. Acoustic change responses to amplitude modulation: a method to quantify cortical temporal processing and hemispheric asymmetry

    PubMed Central

    Han, Ji Hye; Dimitrijevic, Andrew

    2015-01-01

    Objective: Sound modulation is a critical temporal cue for the perception of speech and environmental sounds. To examine auditory cortical responses to sound modulation, we developed an acoustic change stimulus involving amplitude modulation (AM) of ongoing noise. The AM transitions in this stimulus evoked an acoustic change complex (ACC) that was examined parametrically in terms of rate and depth of modulation and hemispheric symmetry. Methods: Auditory cortical potentials were recorded from 64 scalp electrodes during passive listening in two conditions: (1) ACC from white noise to 4, 40, 300 Hz AM, with varying AM depths of 100, 50, 25% lasting 1 s and (2) 1 s AM noise bursts at the same modulation rate. Behavioral measures included AM detection from an attend ACC condition and AM depth thresholds (i.e., a temporal modulation transfer function, TMTF). Results: The N1 response of the ACC was large to 4 and 40 Hz and small to the 300 Hz AM. In contrast, the opposite pattern was observed with bursts of AM showing larger responses with increases in AM rate. Brain source modeling showed significant hemispheric asymmetry such that 4 and 40 Hz ACC responses were dominated by right and left hemispheres respectively. Conclusion: N1 responses to the ACC resembled a low pass filter shape similar to a behavioral TMTF. In the ACC paradigm, the only stimulus parameter that changes is AM and therefore the N1 response provides an index for this AM change. In contrast, an AM burst stimulus contains both AM and level changes and is likely dominated by the rise time of the stimulus. The hemispheric differences are consistent with the asymmetric sampling in time hypothesis suggesting that the different hemispheres preferentially sample acoustic time across different time windows. Significance: The ACC provides a novel approach to studying temporal processing at the level of cortex and provides further evidence of hemispheric specialization for fast and slow stimuli. PMID:25717291

  1. Acoustic Predictors of Intelligibility for Segmentally Interrupted Speech: Temporal Envelope, Voicing, and Duration

    ERIC Educational Resources Information Center

    Fogerty, Daniel

    2013-01-01

    Purpose: Temporal interruption limits the perception of speech to isolated temporal glimpses. An analysis was conducted to determine the acoustic parameter that best predicts speech recognition from temporal fragments that preserve different types of speech information--namely, consonants and vowels. Method: Young listeners with normal hearing…

  2. Multimodal far-field acoustic radiation pattern: An approximate equation

    NASA Technical Reports Server (NTRS)

    Rice, E. J.

    1977-01-01

    The far-field sound radiation theory for a circular duct was studied for both single mode and multimodal inputs. The investigation was intended to develop a method to determine the acoustic power produced by turbofans as a function of mode cut-off ratio. With reasonable simplifying assumptions the single mode radiation pattern was shown to be reducible to a function of mode cut-off ratio only. With modal cut-off ratio as the dominant variable, multimodal radiation patterns can be reduced to a simple explicit expression. This approximate expression provides excellent agreement with an exact calculation of the sound radiation pattern using equal acoustic power per mode.

  3. Surface wave patterns on acoustically levitated viscous liquid alloys

    NASA Astrophysics Data System (ADS)

    Hong, Z. Y.; Yan, N.; Geng, D. L.; Wei, B.

    2014-04-01

    We demonstrate two different kinds of surface wave patterns on viscous liquid alloys, which are melted and solidified under acoustic levitation condition. These patterns are consistent with the morphologies of standing capillary waves and ensembles of oscillons, respectively. The rapid solidification of two-dimensional liquid alloy surfaces may hold them down.

  4. Scaling properties in temporal patterns of schizophrenia

    NASA Astrophysics Data System (ADS)

    Dünki, R. M.; Ambühl, B.

    1996-02-01

    Investigations into the patterns of schizophrenia reveal evidence of scaling properties in temporal behaviour. This is shown in the spectral properties of mid-range and long-range (up to two years) daily recordings from a sample of patients drawn at the therapeutic dwelling SOTERIA (Ambühl et al., in: Springer Series in Synergetics, Vol. 58, eds. Tschacher et al. (Springer, Berlin, 1992) pp. 195-203 and references therein) of the Psychiatric University Hospital in Bern. The therapeutic setting is unique in that it tries to avoid treatment by medication. Power law behaviour has been found within fractal walk analysis and Fourier spectra for the daily fluctuations. A simple dynamic principle, based on a generic intermittency model, is put in relation to these time series thus predicting an additional scaling law for the distribution P( T) of time spans T between successive hospitalizations. Testing this hypothesis with our data shows only insignificant deviations. A possible role of this dynamic principle in the risk assignment of psychotic phases is explored with the help of an example.

  5. Spectro-temporal modulation masking patterns reveal frequency selectivity.

    PubMed

    Oetjen, Arne; Verhey, Jesko L

    2015-02-01

    The present study investigated the possibility that the human auditory system demonstrates frequency selectivity to spectro-temporal amplitude modulations. Threshold modulation depth for detecting sinusoidal spectro-temporal modulations was measured using a generalized masked threshold pattern paradigm with narrowband masker modulations. Four target spectro-temporal modulations were examined, differing in their temporal and spectral modulation frequencies: a temporal modulation of -8, 8, or 16?Hz combined with a spectral modulation of 1 cycle/octave and a temporal modulation of 4?Hz combined with a spectral modulation of 0.5 cycles/octave. The temporal center frequencies of the masker modulation ranged from 0.25 to 4 times the target temporal modulation. The spectral masker-modulation center-frequencies were 0, 0.5, 1, 1.5, and 2 times the target spectral modulation. For all target modulations, the pattern of average thresholds for the eight normal-hearing listeners was consistent with the hypothesis of a spectro-temporal modulation filter. Such a pattern of modulation-frequency sensitivity was predicted on the basis of psychoacoustical data for purely temporal amplitude modulations and purely spectral amplitude modulations. An analysis of separability indicates that, for the present data set, selectivity in the spectro-temporal modulation domain can be described by a combination of a purely spectral and a purely temporal modulation filter function. PMID:25698006

  6. Coding of multisensory temporal patterns in human superior temporal sulcus

    PubMed Central

    Noesselt, Tömme; Bergmann, Daniel; Heinze, Hans-Jochen; Münte, Thomas; Spence, Charles

    2012-01-01

    Philosophers, psychologists, and neuroscientists have long been interested in how the temporal aspects of perception are represented in the brain. In the present study, we investigated the neural basis of the temporal perception of synchrony/asynchrony for audiovisual speech stimuli using functional magnetic resonance imaging (fMRI). Subjects judged the temporal relation of (a)synchronous audiovisual speech streams, and indicated any changes in their perception of the stimuli over time. Differential hemodynamic responses for synchronous versus asynchronous stimuli were observed in the multisensory superior temporal sulcus complex (mSTS-c) and prefrontal cortex. Within mSTS-c we found adjacent regions expressing an enhanced BOLD-response to the different physical (a)synchrony conditions. These regions were further modulated by the subjects' perceptual state. By calculating the distances between the modulated regions within mSTS-c in single-subjects we demonstrate that the “auditory leading (AL)” and “visual leading (VL) areas” lie closer to “synchrony areas” than to each other. Moreover, analysis of interregional connectivity indicates a stronger functional connection between multisensory prefrontal cortex and mSTS-c during the perception of asynchrony. Taken together, these results therefore suggest the presence of distinct sub-regions within the human STS-c for the maintenance of temporal relations for audiovisual speech stimuli plus differential functional connectivity with prefrontal regions. The respective local activity in mSTS-c is dependent both upon the physical properties of the stimuli presented and upon the subjects' perception of (a)synchrony. PMID:22973202

  7. Predicting the temporal responses of non-phase-locking bullfrog auditory units to complex acoustic waveforms.

    PubMed

    Yamada, W M; Lewis, E R

    1999-04-01

    Axons from the basilar papilla of the American bullfrog (Rana catesbeiana) do not phase lock to stimuli within an octave of their best frequencies. Nevertheless, they show consistent temporal patterns of instantaneous spike rate (as reflected in peristimulus time histograms) in response to repeated stimuli in that frequency range. We show that the second-order Wiener kernels for these axons, derived from the cross-correlation of continuous (non-repeating), broad-band noise stimulus with the spike train produced in response to that stimulus, can predict with considerable precision the temporal pattern of instantaneous spike rate in response to a novel, complex acoustic waveform (a repeated, 100-ms segment of noise, band-limited to cover the single octaves above and below best frequency). Furthermore, we show that most of this predictive power is retained when the second-order Wiener kernel is reduced to the highest-ranking pair of singular vectors derived from singular-value decomposition, that the retained pair of vectors corresponds to a single auditory filter followed by an envelope-detection process, and that the auditory filter itself predicts the characteristic frequency (CF) of the axon and the shape of the frequency-threshold tuning curve in the vicinity of CF. PMID:10320106

  8. 1987 WET DEPOSITION TEMPORAL AND SPATIAL PATTERNS IN NORTH AMERICA

    EPA Science Inventory

    The focus of this report is on North American wet deposition temporal patterns from 1979 to 1987 and spatial patterns for 1987. he report investigates the patterns of annual precipitation-weighted average concentration and annual deposition for nine ion species: hydrogen, sulfate...

  9. Tunable Nanowire Patterning Using Standing Surface Acoustic Waves

    PubMed Central

    Chen, Yuchao; Ding, Xiaoyun; Lin, Sz-Chin Steven; Yang, Shikuan; Huang, Po-Hsun; Nama, Nitesh; Zhao, Yanhui; Nawaz, Ahmad Ahsan; Guo, Feng; Wang, Wei; Gu, Yeyi; Mallouk, Thomas E.; Huang, Tony Jun

    2014-01-01

    Patterning of nanowires in a controllable, tunable manner is important for the fabrication of functional nanodevices. Here we present a simple approach for tunable nanowire patterning using standing surface acoustic waves (SSAW). This technique allows for the construction of large-scale nanowire arrays with well-controlled patterning geometry and spacing within 5 seconds. In this approach, SSAWs were generated by interdigital transducers (IDTs), which induced a periodic alternating current (AC) electric field on the piezoelectric substrate and consequently patterned metallic nanowires in suspension. The patterns could be deposited onto the substrate after the liquid evaporated. By controlling the distribution of the SSAW field, metallic nanowires were assembled into different patterns including parallel and perpendicular arrays. The spacing of the nanowire arrays could be tuned by controlling the frequency of the surface acoustic waves. Additionally, we observed 3D spark-shape nanowire patterns in the SSAW field. The SSAW-based nanowire-patterning technique presented here possesses several advantages over alternative patterning approaches, including high versatility, tunability, and efficiency, making it promising for device applications. PMID:23540330

  10. Discovering Temporal Patterns for Intervalbased Events

    E-print Network

    Fu, Ada Waichee

    or pattern over time. In market­basket data, we can have a pattern like ``75% of customers buy peanuts when correlations among peanuts, butter and bread so that we can have better planning for marketing strategy

  11. 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…

  12. 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.

  13. Temporal Patterns of Communication in the Workplace

    ERIC Educational Resources Information Center

    Su, Norman Makoto

    2009-01-01

    In this dissertation, we report on results of an in-depth observational study to understand the temporal dimension of communication in the workplace. By employing the "shadowing" method for in situ to-the-second data gathering of information workers' behaviors, we gained a detailed snapshot of informants' workdays, "warts and all." Our…

  14. Temporal patterns of coarticulation: lip rounding.

    PubMed

    Bell-Berti, F; Harris, K S

    1982-02-01

    According to some theories, anticipatory coarticulation occurs when phones for which a feature is unspecified precede one for which the feature is specified, with consequent migration of the feature value to the antecedent phones. Carryover coarticulation, on the other hand, is often attributed to "articulatory sluggishness." In this paper, EMG evidence is provided that this formulation is inadequate, since the beginning of EMG activity associated with vowel lip rounding is independent of measures of the acoustic duration of adjacent lingual consonants. We suggest that the vowel-rounding gesture simply co-occurs during predictable intervals with portions of preceding and following lingual consonant articulations. PMID:7069059

  15. Spatial, Temporal and Spatio-Temporal Patterns of Maritime Piracy

    PubMed Central

    Marchione, Elio

    2013-01-01

    Objectives: To examine patterns in the timing and location of incidents of maritime piracy to see whether, like many urban crimes, attacks cluster in space and time. Methods: Data for all incidents of maritime piracy worldwide recorded by the National Geospatial Intelligence Agency are analyzed using time-series models and methods originally developed to detect disease contagion. Results: At the macro level, analyses suggest that incidents of pirate attacks are concentrated in five subregions of the earth’s oceans and that the time series for these different subregions differ. At the micro level, analyses suggest that for the last 16 years (or more), pirate attacks appear to cluster in space and time suggesting that patterns are not static but are also not random. Conclusions: Much like other types of crime, pirate attacks cluster in space, and following an attack at one location the risk of others at the same location or nearby is temporarily elevated. The identification of such regularities has implications for the understanding of maritime piracy and for predicting the future locations of attacks. PMID:25076796

  16. Spatial and temporal patterns in conterminous United States streamflow characteristics

    NASA Astrophysics Data System (ADS)

    McCabe, Gregory J.; Wolock, David M.

    2014-10-01

    Spatial and temporal patterns in annual and seasonal minimum, mean, and maximum daily streamflow values were examined for a set of 516 reference stream gauges located throughout the conterminous United States for the period 1951-2009. Cluster analysis was used to classify the stream gauges into 14 groups based on similarity in their temporal patterns of streamflow. The results indicated that the temporal patterns in flow metrics (1) have strong spatial coherence within each region, (2) are similar among the three annual flow metrics and the four seasonal flow metrics within each region, (3) indicate some small magnitude trends over time, and (4) are only weakly associated with well-known climate indices. We conclude that most of the temporal variability in flow is unpredictable in terms of relations to climate indices and infer that, for the most part, future changes in flow characteristics cannot be predicted by these indices.

  17. Eleutherodactylus frogs show frequency but no temporal partitioning: implications for the acoustic niche hypothesis

    PubMed Central

    2014-01-01

    Individuals in acoustic communities compete for the use of the sound resource for communication, a problem that can be studied as niche competition. The acoustic niche hypothesis presents a way to study the partitioning of the resource, but the studies have to take into account the three dimensions of this niche: time, acoustic frequency, and space. I used an Automated Digital Recording System to determine the partitioning of time and acoustic frequency of eight frogs of the genus Eleutherodactylus from Puerto Rico. The calling activity was measured using a calling index. The community exhibited no temporal partitioning since most species called at the same time, between sunset and midnight. The species partitioned the acoustic frequency of their signals, which, in addition to the microhabitat partitioning, can provide some insight into how these species deal with the problem. This data also suggest that monitoring projects with this group should take place only before midnight to avoid false negatives. PMID:25101228

  18. Engaging concert hall acoustics is made up of temporal envelope preserving reflections.

    PubMed

    Lokki, Tapio; Pätynen, Jukka; Tervo, Sakari; Siltanen, Samuel; Savioja, Lauri

    2011-06-01

    Strong, exciting, and engaging sound is perceived in the best concert halls. Here, it is shown that wideband early reflections that preserve the temporal envelope of sound contribute to the clear and open acoustics with strong bass. Such reflections are fused with the direct sound due to the precedence effect. In contrast, reflections that distort the temporal envelope render the sound weak and muddy because they partially break down the precedence. The presented findings are based on the earlier psychoacoustics research, and confirmed by a perceptual evaluation with six simulated concert halls that have same monaural room acoustical parameter values according to ISO3382-1. PMID:21682356

  19. T-Patterns Revisited: Mining for Temporal Patterns in Sensor Data

    PubMed Central

    Salah, Albert Ali; Pauwels, Eric; Tavenard, Romain; Gevers, Theo

    2010-01-01

    The trend to use large amounts of simple sensors as opposed to a few complex sensors to monitor places and systems creates a need for temporal pattern mining algorithms to work on such data. The methods that try to discover re-usable and interpretable patterns in temporal event data have several shortcomings. We contrast several recent approaches to the problem, and extend the T-Pattern algorithm, which was previously applied for detection of sequential patterns in behavioural sciences. The temporal complexity of the T-pattern approach is prohibitive in the scenarios we consider. We remedy this with a statistical model to obtain a fast and robust algorithm to find patterns in temporal data. We test our algorithm on a recent database collected with passive infrared sensors with millions of events. PMID:22163613

  20. Extended-range temporal electronic speckle pattern interferometry

    NASA Astrophysics Data System (ADS)

    Servin, Manuel; Davila, Abundio; Quiroga, Juan Antonio

    2002-08-01

    In recent years the availability of high-speed digital video cameras has motivated the study of electronic speckle pattern interferometry (ESPI) in the time domain. To this end a properly sampled temporal sequence of N-fringe patterns is used to analyze the temporal experiment. Samples of temporal speckle images must fulfill the Nyquist criteria over the time axis. When the transient phenomena under study are too fast, the required sampling frequency over time may not be fulfilled. In that case one needs to extend the measuring range of the algorithm used to extract the modulating phase. We analyze how to use short laser pulses or short video acquisition times with fairly long temporal separation among them to estimate the modulating phase of a dynamic ESPI experiment. The only requirement is that the modulating phase being estimated be properly sampled in the spatial domain.

  1. Temporal and spatial patterns of gene profiles during chondrogenic differentiation.

    PubMed

    Skreti, G; Bei, E S; Kalantzaki, K; Zervakis, M

    2014-05-01

    Clustering analysis based on temporal profile of genes may provide new insights in particular biological processes or conditions. We report such an integrative clustering analysis which is based on the expression patterns but is also influenced by temporal changes. The proposed platform is illustrated with a temporal gene expression dataset comprised of pellet culture-conditioned human primary chondrocytes and human bone marrow-derived mesenchymal stem cells (MSCs). We derived three clusters in each cell type and compared the content of these classes in terms of temporal changes. We further considered the induced biological processes and the gene-interaction networks formed within each cluster and discuss their biological significance. Our proposed methodology provides a consistent tool that facilitates both the statistical and biological validation of temporal profiles through spatial gene network profiles. PMID:24808223

  2. Complex temporal and spatial patterns in nonequilibrium systems

    SciTech Connect

    Swinney, H.L.

    1991-09-01

    Dynamical systems methods are being developed and used to characterize the formation and evolution of temporal and spatial patterns in systems maintained far from equilibrium. In particular, experiments and analyses are considering electrodeposition of fractal metallic clusters, pattern formation in reaction-diffusion systems, and the primary instabilities of some fluid flows. Novel reactors have been developed to search for chemical patterns (spatial variations in the chemical composition), and sustained patterns have been found in several different one- and two-dimensional geometries. Bifurcations in these patterns are studied by varying control parameters, e.g., the concentrations of the feed chemicals or the temperature. The observed two-dimensional chemical patterns range from the stationary patterns, similar to those predicted by Turing in 1952 but not observed until 1990, to chemical turbulence, which is characterized by large numbers of defects and a rapid decay of spatial correlations. These provide general insights into the formation of spatiotemporal patterns in nonequilibrium systems.

  3. Detecting Multineuronal Temporal Patterns in Parallel Spike Trains

    PubMed Central

    Gansel, Kai S.; Singer, Wolf

    2012-01-01

    We present a non-parametric and computationally efficient method that detects spatiotemporal firing patterns and pattern sequences in parallel spike trains and tests whether the observed numbers of repeating patterns and sequences on a given timescale are significantly different from those expected by chance. The method is generally applicable and uncovers coordinated activity with arbitrary precision by comparing it to appropriate surrogate data. The analysis of coherent patterns of spatially and temporally distributed spiking activity on various timescales enables the immediate tracking of diverse qualities of coordinated firing related to neuronal state changes and information processing. We apply the method to simulated data and multineuronal recordings from rat visual cortex and show that it reliably discriminates between data sets with random pattern occurrences and with additional exactly repeating spatiotemporal patterns and pattern sequences. Multineuronal cortical spiking activity appears to be precisely coordinated and exhibits a sequential organization beyond the cell assembly concept. PMID:22661942

  4. Finding Spatio-Temporal Patterns in Earth Science Data

    Microsoft Academic Search

    Pang-Ning Tan; Michael Steinbach; Vipin Kumar; Christopher Potter; Steven Klooster; Alicia Torregrosa

    2001-01-01

    This paper presents preliminary work in using data mining techniques to find interesting spatio-temporal patterns from Earth Science data. The data consists of time series measurements for various Earth science and climate variables (e.g. soil moisture, temperature, and precipitation), along with additional data from existing ecosystem models (e.g. Net Primary Production). The ecological patterns of interest include associations, clusters, predictive

  5. 1988 Wet deposition temporal and spatial patterns in North America

    SciTech Connect

    Simpson, J.C.; Olsen, A.R.; Bittner, E.A.

    1992-03-01

    The focus of this report is on North American wet deposition temporal patterns from 1979 to 1988 and spatial patterns for 1988. It is the third in a series of reports that investigate the patterns of annual precipitation-weighted average concentration and annual deposition for nine ion species: hydrogen, sulfate, nitrate, ammonium, calcium, chloride, sodium, potassium, and magnesium. Mosaic maps, based on surface estimation using kriging, display concentration and deposition spatial patterns of pH, hydrogen, sulfate, nitrate, ammonium, and calcium ion species for 1988 annual, winter, and summer periods. Temporal pattern analyses use a subset of 35 sites over a 10-year (1979--1988) period and an expanded subset of 137 sites, with greater spatial coverage, over a 7-year (1982--1988) period. The 10-year period represents the longest period with wet deposition monitoring data available that has a sufficient number of sites with data of known quality to allow a descriptive summary of annual temporal patterns. Sen's median trend estimate and Kendall's seasonal tau (KST) test are calculated for each ion species concentration and deposition at each site in both subsets.

  6. 1988 Wet deposition temporal and spatial patterns in North America

    SciTech Connect

    Simpson, J.C.; Olsen, A.R.; Bittner, E.A.

    1992-03-01

    The focus of this report is on North American wet deposition temporal patterns from 1979 to 1988 and spatial patterns for 1988. It is the third in a series of reports that investigate the patterns of annual precipitation-weighted average concentration and annual deposition for nine ion species: hydrogen, sulfate, nitrate, ammonium, calcium, chloride, sodium, potassium, and magnesium. Mosaic maps, based on surface estimation using kriging, display concentration and deposition spatial patterns of pH, hydrogen, sulfate, nitrate, ammonium, and calcium ion species for 1988 annual, winter, and summer periods. Temporal pattern analyses use a subset of 35 sites over a 10-year (1979--1988) period and an expanded subset of 137 sites, with greater spatial coverage, over a 7-year (1982--1988) period. The 10-year period represents the longest period with wet deposition monitoring data available that has a sufficient number of sites with data of known quality to allow a descriptive summary of annual temporal patterns. Sen`s median trend estimate and Kendall`s seasonal tau (KST) test are calculated for each ion species concentration and deposition at each site in both subsets.

  7. Spatial, temporal and muscle action patterns of Tai Chi gait

    Microsoft Academic Search

    Ge Wu; Wei Liu; Juvena Hitt; Debra Millon

    2004-01-01

    This study was to quantitatively characterize the spatial, temporal, and neuromuscular activation patterns of Tai Chi gait (TCG). Ten healthy young subjects were tested. The kinematics of TCG and normal gait (NG) were measured using a marker-based motion analysis system and two biomechanical force plates. Surface electromyography (EMG) was recorded from six left-side muscles: tibialis anterior, soleus, peronaeus longus, rectus

  8. Visual pattern recognition based on spatio-temporal patterns of retinal ganglion cells' activities.

    PubMed

    Jing, Wei; Liu, Wen-Zhong; Gong, Xin-Wei; Gong, Hai-Qing; Liang, Pei-Ji

    2010-09-01

    Neural information is processed based on integrated activities of relevant neurons. Concerted population activity is one of the important ways for retinal ganglion cells to efficiently organize and process visual information. In the present study, the spike activities of bullfrog retinal ganglion cells in response to three different visual patterns (checker-board, vertical gratings and horizontal gratings) were recorded using multi-electrode arrays. A measurement of subsequence distribution discrepancy (MSDD) was applied to identify the spatio-temporal patterns of retinal ganglion cells' activities in response to different stimulation patterns. The results show that the population activity patterns were different in response to different stimulation patterns, such difference in activity pattern was consistently detectable even when visual adaptation occurred during repeated experimental trials. Therefore, the stimulus pattern can be reliably discriminated according to the spatio-temporal pattern of the neuronal activities calculated using the MSDD algorithm. PMID:21886670

  9. Visual pattern recognition based on spatio-temporal patterns of retinal ganglion cells’ activities

    PubMed Central

    Jing, Wei; Liu, Wen-Zhong; Gong, Xin-Wei; Gong, Hai-Qing

    2010-01-01

    Neural information is processed based on integrated activities of relevant neurons. Concerted population activity is one of the important ways for retinal ganglion cells to efficiently organize and process visual information. In the present study, the spike activities of bullfrog retinal ganglion cells in response to three different visual patterns (checker-board, vertical gratings and horizontal gratings) were recorded using multi-electrode arrays. A measurement of subsequence distribution discrepancy (MSDD) was applied to identify the spatio-temporal patterns of retinal ganglion cells’ activities in response to different stimulation patterns. The results show that the population activity patterns were different in response to different stimulation patterns, such difference in activity pattern was consistently detectable even when visual adaptation occurred during repeated experimental trials. Therefore, the stimulus pattern can be reliably discriminated according to the spatio-temporal pattern of the neuronal activities calculated using the MSDD algorithm. PMID:21886670

  10. Temporal patterns of phytoplankton abundance in the North Atlantic

    NASA Technical Reports Server (NTRS)

    Campbell, Janet W.

    1989-01-01

    A time series of CZCS images is being developed to study phytoplankton distribution patterns in the North Atlantic. The goal of this study is to observe temporal variability in phytoplankton pigments and other organic particulates, and to infer from these patterns the potential flux of biogenic materials from the euphotic layer to the deep ocean. Early results of this project are presented in this paper. Specifically, the satellite data used were 13 monthly composited images of CZCS data for the North Atlantic from January 1979 to January 1980. Results are presented for seasonal patterns along the 20 deg W meridian.

  11. 1986 wet deposition temporal and spatial patterns in North America

    SciTech Connect

    Olsen, A.R.

    1989-07-01

    The focus of this report is on North American wet deposition temporal patterns from 1979 to 1986 and spatial patterns for 1986. The report provides statistical distribution summaries of annual precipitation-weighted average concentration and annual deposition for nine ion species: hydrogen, sulfate, nitrate, ammonium, calcium, chloride, sodium, potassium, and magnesium. The data in the report are from the Acid Depositing System (ADS) for the statistical reporting of North American deposition data. Isopleth maps, based on surface estimation using kriging, display concentration and deposition spatial patterns of pH, hydrogen, sulfate, nitrate, ammonium, and calcium ion species for 1986 annual, winter, and summer periods. The temporal pattern analyses use a subset of 30 sites over an 8-year (1979-1986) period and an expanded subset of 137 sites with greater spatial coverage over a 5-year (1982-1986) period. The 8-year period represents the longest period with wet deposition monitoring data unavailable that has a sufficient number of sites with data of known quality to allow a descriptive summary of annual temporal patterns. 19 refs., 105 figs., 29 tabs.

  12. Acoustic Waves and Farfield Patterns in Two Dimensional Oceans with Porouselastic Seabeds

    E-print Network

    Acoustic Waves and Far­field Patterns in Two Dimensional Oceans with Porous­elastic Seabeds R. P of acoustic wave in an ocean with elastic­ porous sediment. A Biot model presented in [1] and [2] is adopted. Gilbert 1 and Yongzhi Xu 2 Abstract In this paper we study the propagation of acoustic waves in two

  13. Fault diagnosis of internal combustion engines using visual dot patterns of acoustic and vibration signals

    Microsoft Academic Search

    Jian-Da Wu; Chao-Qin Chuang

    2005-01-01

    An investigation of the fault diagnosis technique in internal combustion engines based on the visual dot pattern of acoustic and vibration signals is presented in this paper. Acoustic emissions and vibration signals are well known as being able to be used for monitoring the conditions of rotating machineries. Most of the conventional methods for fault diagnosis using acoustic and vibration

  14. Effect of the temporal pattern of contralateral inhibition on sound localization cues.

    PubMed

    Marsat, Gary; Pollack, Gerald S

    2005-06-29

    We studied the temporal coding properties of identified interneurons in the auditory system of crickets, using information theory as an analytical tool. The ascending neuron 1 (AN1), which is tuned to the dominant carrier frequency (CF) of cricket songs, selectively codes the limited range of amplitude modulation (AM) frequencies that occur in these signals. AN2, which is most sensitive to the ultrasonic frequencies that occur in echolocation calls of insectivorous bats, codes a broader range of AM frequencies, as occur in bat calls. A third neuron, omega neuron 1 (ON1), which is dually tuned to both ranges of carrier frequency, was shown previously to have CF-specific coding properties, allowing it to represent accurately the differing temporal structures of both cricket songs and bat calls. ON1 is a source of contralateral inhibition to AN1 and AN2, enhancing binaural contrast and facilitating sound localization. We used dichotic stimulation to examine the importance of the temporal structure of contralateral inhibition for enhancing binaural contrast. Contralateral inhibition degrades the coding of temporal pattern by AN1 and AN2, but only if the temporal pattern of inhibitory input matches that of excitation. Firing rate is also decreased most strongly by temporally matched contralateral inhibition. This is apparent for AN1 in its mean firing rate; for AN2, high-frequency firing is selectively suppressed. Our results show that the CF-specific coding properties of ON1 allow this single neuron to enhance effectively localization cues for both cricket-like and bat-like acoustic signals. PMID:15987943

  15. Music Perception with Temporal Cues in Acoustic and Electric Hearing

    Microsoft Academic Search

    Ying-Yee Kong; Rachel Cruz; J. Ackland Jones; Fan-Gang Zeng

    2004-01-01

    Design: Both normal-hearing and cochlear implant listeners participated in the experiments. Tempo discrimination was measured in a two-interval forced-choice procedure in which subjects were asked to choose the faster tempo at four standard tempo conditions (60, 80, 100, and 120 beats per minute). For rhythmic pattern identification, seven different rhythmic patterns were created and sub- jects were asked to read

  16. Impaired extraction of speech rhythm from temporal modulation patterns in speech in developmental dyslexia

    PubMed Central

    Leong, Victoria; Goswami, Usha

    2014-01-01

    Dyslexia is associated with impaired neural representation of the sound structure of words (phonology). The “phonological deficit” in dyslexia may arise in part from impaired speech rhythm perception, thought to depend on neural oscillatory phase-locking to slow amplitude modulation (AM) patterns in the speech envelope. Speech contains AM patterns at multiple temporal rates, and these different AM rates are associated with phonological units of different grain sizes, e.g., related to stress, syllables or phonemes. Here, we assess the ability of adults with dyslexia to use speech AMs to identify rhythm patterns (RPs). We study 3 important temporal rates: “Stress” (~2 Hz), “Syllable” (~4 Hz) and “Sub-beat” (reduced syllables, ~14 Hz). 21 dyslexics and 21 controls listened to nursery rhyme sentences that had been tone-vocoded using either single AM rates from the speech envelope (Stress only, Syllable only, Sub-beat only) or pairs of AM rates (Stress + Syllable, Syllable + Sub-beat). They were asked to use the acoustic rhythm of the stimulus to identity the original nursery rhyme sentence. The data showed that dyslexics were significantly poorer at detecting rhythm compared to controls when they had to utilize multi-rate temporal information from pairs of AMs (Stress + Syllable or Syllable + Sub-beat). These data suggest that dyslexia is associated with a reduced ability to utilize AMs <20 Hz for rhythm recognition. This perceptual deficit in utilizing AM patterns in speech could be underpinned by less efficient neuronal phase alignment and cross-frequency neuronal oscillatory synchronization in dyslexia. Dyslexics' perceptual difficulties in capturing the full spectro-temporal complexity of speech over multiple timescales could contribute to the development of impaired phonological representations for words, the cognitive hallmark of dyslexia across languages. PMID:24605099

  17. Auditory cortex mediates the perceptual effects of acoustic temporal expectation

    PubMed Central

    Jaramillo, Santiago; Zador, Anthony M.

    2011-01-01

    When events occur at predictable instants, anticipation improves performance. Knowledge of event timing modulates motor circuits, improving response speed. By contrast, the neuronal mechanisms underlying changes in sensory perception due to expectation are not well understood. We have developed a novel behavioral paradigm for rats in which we manipulated expectations about sound timing. Valid expectations improved both the speed and the accuracy of subjects’ performance, indicating not only improved motor preparedness but also enhanced perception. Single neuron recordings in primary auditory cortex revealed enhanced representation of sounds during periods of heightened expectation. Furthermore, we found that activity in auditory cortex was causally linked to the performance of the task, and that changes in the neuronal representation of sounds predicted performance on a trial-by-trial basis. Our results indicate that changes in neuronal representation as early as primary sensory cortex mediate the perceptual advantage conferred by temporal expectation. PMID:21170056

  18. Acoustic emission patterns from the surfaces of red oak wafers under transverse bending stress

    Microsoft Academic Search

    R. W. Rice; Ch. Skaar

    1990-01-01

    One of the applications of acoustic emission (AE) technology in the forest products field is likely to be in monitoring and\\/or controlling the drying of wood. This report describes experiments designed to monitor the acoustic emission patterns from the lower surfaces of small red oak test beams which were undergoing failure in tension perpendicular to the grain. Similar patterns are

  19. Acceleration of ultrasound thermal therapy by patterned acoustic droplet vaporization

    PubMed Central

    Kripfgans, Oliver D.; Zhang, Man; Fabiilli, Mario L.; Carson, Paul L.; Padilla, Frederic; Swanson, Scott D.; Mougenot, Charles; Brian Fowlkes, J.; Mougenot, Charles

    2014-01-01

    One application of acoustic droplet vaporization (ADV), a method of converting biocompatible microdroplets into microbubbles, is to enhance locally high intensity focused ultrasound (HIFU) therapy. Two objectives are pursued here: (1) the controlled creation of a bubble trench prior to HIFU using ADV and (2) use of the trench for increasing ablation volumes, lowering acoustic powers, and decreasing therapy duration. Thermally responsive phantoms were made with perfluorocarbon emulsion. Compound lesions were formed in a laboratory setting and a clinical magnetic resonance imaging (MRI)-guided HIFU system. Linear and spiral patterned compound lesions were generated in trenches. A larger fraction of the HIFU beam is contained to increase the generation of heat. Using the laboratory system, a 90?mm linear length spiral trench was formed in 30?s with mechanical beam steering. Comparatively, the clinical HIFU system formed a 19.9?mm linear length spiral trench in approximately 1?s with electronic beam steering. Lesions were imaged optically and with MRI. A uniform thermal ablation volume of 3.25?mL was achieved in 55.4?s (4-times faster than standard clinical HIFU and 14-times larger volume versus sum of individual lesions). Single lesions showed a 400% volume increase. PMID:24437794

  20. 1987 wet deposition temporal and spatial patterns in North America

    SciTech Connect

    Simpson, J.C.; Olsen, A.R.

    1990-03-01

    The focus of this report is on North American wet deposition temporal patterns from 1979 to 1987 and spatial patterns for 1987. The report investigates the patterns of annual precipitation-weighted average concentration and annual deposition for nine ion species: hydrogen, sulfate, nitrate, ammonium, calcium, chloride, sodium, potassium, and magnesium. Data are from the Acid Deposition System (ADS) for the statistical reporting of North American deposition data which includes the National Atmospheric Deposition Program/National Trends Network (NADP/NTN), the MAP3S precipitation chemistry network, the Utility Acid Precipitation Study Program (UAPSP), the Canadian Precipitation Monitoring Network (CAPMoN), and the daily and 4-weekly Acidic Precipitation in Ontario Study (APIOS-D and APIOS-C). Mosaic maps, based on surface estimation using kriging, display concentration and deposition spatial patterns of pH, hydrogen, sulfate, nitrate, ammonium, and calcium ion species for 1987 annual, winter, and summer periods. The temporal pattern analyses use a subset of 39 sites over a 9-year (1979--1987) period and an expanded subset of 140 sites with greater spatial coverage over a 6-year (1982--1987) period. 68 refs., 15 figs., 15 tabs.

  1. Spontaneous Firings of Carnivorous Aquatic Utricularia Traps: Temporal Patterns and Mechanical Oscillations

    E-print Network

    Paris-Sud XI, Université de

    Spontaneous Firings of Carnivorous Aquatic Utricularia Traps: Temporal Patterns and Mechanical are carnivorous plants living in environments poor in nutrients. Their trapping mechanism has fascinated) Spontaneous Firings of Carnivorous Aquatic Utricularia Traps: Temporal Patterns and Mechanical Oscillations

  2. Acoustic droplet–hydrogel composites for spatial and temporal control of growth factor delivery and scaffold stiffness

    PubMed Central

    Fabiilli, Mario L.; Wilson, Christopher G.; Padilla, Frédéric; Martín-Saavedra, Francisco M.; Fowlkes, J. Brian; Franceschi, Renny T.

    2013-01-01

    Wound healing is regulated by temporally and spatially restricted patterns of growth factor signaling, but there are few delivery vehicles capable of the “on-demand” release necessary for recapitulating these patterns. Recently we described a perfluorocarbon double emulsion that selectively releases a protein payload upon exposure to ultrasound through a process known as acoustic droplet vaporization (ADV). In this study, we describe a delivery system composed of fibrin hydrogels doped with growth factor-loaded double emulsion for applications in tissue regeneration. Release of immunoreactive basic fibroblast growth factor (bFGF) from the composites increased up to 5-fold following ADV and delayed release was achieved by delaying exposure to ultrasound. Releasates of ultrasound-treated materials significantly increased the proliferation of endothelial cells compared to sham controls, indicating that the released bFGF was bioactive. ADV also triggered changes in the ultrastructure and mechanical properties of the fibrin as bubble formation and consolidation of the fibrin in ultrasound-treated composites were accompanied by up to a 22-fold increase in shear stiffness. ADV did not reduce the viability of cells suspended in composite scaffolds. These results demonstrate that an acoustic droplet–hydrogel composite could have broad utility in promoting wound healing through on-demand control of growth factor release and/or scaffold architecture. PMID:23535233

  3. Spatial and temporal patterns of cuttlefish (Sepia officinalis) abundance and environmental influences a case study using

    E-print Network

    Pierce, Graham

    Spatial and temporal patterns of cuttlefish (Sepia officinalis) abundance and environmental and temporal patterns of cuttlefish (Sepia officinalis) abundance and environmental influences ­ a case study Journal of Marine Science, 60: 1149­1158. The spatial and temporal distribution patterns of cuttlefish

  4. Planktivorous Fish Recognize Temporal Motion Patterns of Suspended Particles

    NASA Astrophysics Data System (ADS)

    Strickler, J. R.; Tsonis, A.

    2004-12-01

    Small planktivorous fish feed by selective captures of individual zooplankters. We realize that: 1) the predator, as well as the prey is suspended in the water column, which does not provide either with stable reference points; 2) the ambient flow field acts differently on the larger predators than on the much smaller prey; and 3) within the water column there are many suspended particles of lower nutritional value than the zooplankters represent. We investigated in the laboratory whether or not fish can distinguish between small targets moving with different swimming patterns, e.g. particles entrained passively in the ambient water flow versus entrained but actively swimming particles. We created in an aquarium computer-animated stimuli with motion patterns ranging from random to actual swimming motions of live animals. The results show that planktivorous fish can recognize temporal patterns in a visually homogeneous environment. Therefore, blue-water fish must process visual information similar to terrestrial animals processing auditory information.

  5. Listener descriptions of isolated and patterned acoustic transients

    NASA Astrophysics Data System (ADS)

    Ballas, J. A.; Howard, J. H., Jr.; Kolm, C.

    1981-11-01

    A three-phase experiment was conducted to assess listeners' ability to recognize and identify environmental acoustic sounds. The first phase was a free identification of ten short duration recordings of real-world events. The second phase was a free identification of five sequences composed of a subset of these ten transients. These sequences were intended to be meaningful, representing the sounds that could be produced by opening water or steam valves. The third phase was a forced identification of the ten transients using a checklist of descriptors. The results showed that while some types of sounds were identified correctly by most listeners, others were confused and rarely identified correctly. Several metallic sounds were often confused semantically even though they were quite distinct perceptually. The identification of patterns was found to depend upon both the salience of the individual sounds in the pattern and the semantic relationship between the sounds. Finally, it was demonstrated that signal processing errors can have perceptually meaningful effects. An error in processing one of the ten sounds produced a signal which was interpreted consistently by most listeners, but in a manner which had little semantic relationship to the actual event which had been recorded.

  6. The identification of bone regions for the assistance of temporal bone surgery through analysis of the drill acoustics

    Microsoft Academic Search

    Pierce Brady; Martin Hill; Joe Connell; John Barrett; D. OaHare; Peter O Sullivan; Brendan Fennessy

    2009-01-01

    This paper presents a method to identify the bone regions encountered during a temporal bone dissection. This should aid the otolaryngologist in the identification of anatomical landmarks whilst training and performing surgical procedures. The approach adopts the mel frequency cepstrum coefficients and the Mahalanobis distance metric to indentify the temporal bone regions from the acoustic signature of the surgical drill.

  7. Sophisticated Temporal Pattern Recognition in Retinal Ganglion Cells

    PubMed Central

    Schwartz, Greg; Berry, Michael J.

    2010-01-01

    Pattern recognition is one of the most important tasks of the visual system, and uncovering the neural mechanisms underlying recognition phenomena has been a focus of researchers for decades. Surprisingly, at the earliest stages of vision, the retina is capable of highly sophisticated temporal pattern recognition. We stimulated the retina of tiger salamander (Ambystoma tigrinum) with periodic dark flash sequences and found that retinal ganglion cells had a wide variety of different responses to a periodic flash sequence with many firing when a flash was omitted. The timing of the omitted stimulus response (OSR) depended on the period, with individual cells tracking the stimulus period down to increments of 5 ms. When flashes occurred earlier than expected, cells updated their expectation of the next flash time by as much as 50 ms. When flashes occurred later than expected, cells fired an OSR and reset their temporal expectation to the average time interval between flashes. Using pharmacology to investigate the retinal circuitry involved, we found that inhibitory transmission from amacrine cells was not required, but on bipolar cells were required. The results suggest a mechanism in which the intrinsic resonance of on bipolars leads to the OSR in ganglion cells. We discuss the implications of retinal pattern recognition on the neural code of the retina and visual processing in general. PMID:18272878

  8. Sophisticated temporal pattern recognition in retinal ganglion cells.

    PubMed

    Schwartz, Greg; Berry, Michael J

    2008-04-01

    Pattern recognition is one of the most important tasks of the visual system, and uncovering the neural mechanisms underlying recognition phenomena has been a focus of researchers for decades. Surprisingly, at the earliest stages of vision, the retina is capable of highly sophisticated temporal pattern recognition. We stimulated the retina of tiger salamander (Ambystoma tigrinum) with periodic dark flash sequences and found that retinal ganglion cells had a wide variety of different responses to a periodic flash sequence with many firing when a flash was omitted. The timing of the omitted stimulus response (OSR) depended on the period, with individual cells tracking the stimulus period down to increments of 5 ms. When flashes occurred earlier than expected, cells updated their expectation of the next flash time by as much as 50 ms. When flashes occurred later than expected, cells fired an OSR and reset their temporal expectation to the average time interval between flashes. Using pharmacology to investigate the retinal circuitry involved, we found that inhibitory transmission from amacrine cells was not required, but on bipolar cells were required. The results suggest a mechanism in which the intrinsic resonance of on bipolars leads to the OSR in ganglion cells. We discuss the implications of retinal pattern recognition on the neural code of the retina and visual processing in general. PMID:18272878

  9. Spectro-temporal interpretation of activity patterns of auditory neurons.

    PubMed

    Hesselmans, G H; Johannesma, P I

    1989-03-01

    Sensory receptors transform an external sensory stimulus into an internal neural activity pattern. This mapping is studied through its inverse. An earlier paper showed that within the context of a neuron model composed of a linear filter followed by an exponential pulse generator and a Gaussian stimulus ensemble a unique "most plausible" first-order stimulus estimate can be constructed. This method, applicable only to neurons showing phase-lock, is extended to neurons without phase-lock. In this situation second-order spectro-temporal stimulus estimates are produced; examples are given from simulation. The method is applied to activity of neurons in the auditory system of the frog. PMID:2520023

  10. Spectral and Temporal Acoustic Features Modulate Response Irregularities within Primary Auditory Cortex Columns

    PubMed Central

    Carrasco, Andres; Brown, Trecia A.; Lomber, Stephen G.

    2014-01-01

    Assemblies of vertically connected neurons in the cerebral cortex form information processing units (columns) that participate in the distribution and segregation of sensory signals. Despite well-accepted models of columnar architecture, functional mechanisms of inter-laminar communication remain poorly understood. Hence, the purpose of the present investigation was to examine the effects of sensory information features on columnar response properties. Using acute recording techniques, extracellular response activity was collected from the right hemisphere of eight mature cats (felis catus). Recordings were conducted with multichannel electrodes that permitted the simultaneous acquisition of neuronal activity within primary auditory cortex columns. Neuronal responses to simple (pure tones), complex (noise burst and frequency modulated sweeps), and ecologically relevant (con-specific vocalizations) acoustic signals were measured. Collectively, the present investigation demonstrates that despite consistencies in neuronal tuning (characteristic frequency), irregularities in discharge activity between neurons of individual A1 columns increase as a function of spectral (signal complexity) and temporal (duration) acoustic variations. PMID:25494365

  11. Reconstructing spatial and temporal patterns of paleoglaciation across Central Asia

    NASA Astrophysics Data System (ADS)

    Stroeven, Arjen P.

    2014-05-01

    Understanding the behaviour of mountain glaciers and ice caps, the evolution of mountain landscapes, and testing global climate models all require well-constrained information on past spatial and temporal patterns of glacier change. Particularly important are transitional regions that have high spatial and temporal variation in glacier activity and that can provide a sensitive record of past climate change. Central Asia is an extreme continental location with glaciers that have responded sensitively to variations in major regional climate systems. As an international team, we are reconstructing glacial histories of several areas of the Tibetan Plateau as well as along the Tian Shan, Altai and Kunlun Mountains. Building on previous work, we are using remote sensing-based geomorphological mapping augmented with field observations to map out glacial landforms and the maximum distributions of erratics. We then use cosmogenic nuclide Be-10 and Al-26, optically stimulated luminescence, and electron spin resonance dating of moraines and other landforms to compare dating techniques and to constrain the ages of defined extents of paleo-glaciers and ice caps. Comparing consistently dated glacial histories across central Asia provides an opportunity to examine shifts in the dominance patterns of climate systems over time in the region. Results to date show significant variations in the timing and extent of glaciation, including areas in the southeast Tibetan Plateau and Tian Shan with extensive valley and small polythermal ice cap glaciation during the global last glacial maximum in contrast to areas in central and northeast Tibetan Plateau that had very limited valley glacier expansion then. Initial numerical modelling attempting to simulate mapped and dated paleoglacial extents indicates that relatively limited cooling is sufficient to produce observed past expansions of glaciers across the Tibetan Plateau, and predicts complex basal thermal regimes in some locations that match patterns of past glacial erosion inferred from landform patterns and ages. Future modelling will examine glacier behaviour along major mountain ranges across central Asia.

  12. Bacterial colonization of Hydra hatchlings follows a robust temporal pattern

    PubMed Central

    Franzenburg, Sören; Fraune, Sebastian; Altrock, Philipp M; Künzel, Sven; Baines, John F; Traulsen, Arne; Bosch, Thomas CG

    2013-01-01

    Animals are colonized by complex bacterial communities. The processes controlling community membership and influencing the establishment of the microbial ecosystem during development are poorly understood. Here we aimed to explore the assembly of bacterial communities in Hydra with the broader goal of elucidating the general rules that determine the temporal progression of bacterial colonization of animal epithelia. We profiled the microbial communities in polyps at various time points after hatching in four replicates. The composition and temporal patterns of the bacterial communities were strikingly similar in all replicates. Distinct features included high diversity of community profiles in the first week, a remarkable but transient adult-like profile 2 weeks after hatching, followed by progressive emergence of a stable adult-like pattern characterized by low species diversity and the preponderance of the Betaproteobacterium Curvibacter. Intriguingly, this process displayed important parallels to the assembly of human fecal communities after birth. In addition, a mathematical modeling approach was used to uncover the organizational principles of this colonization process, suggesting that both, local environmental or host-derived factor(s) modulating the colonization rate, as well as frequency-dependent interactions of individual bacterial community members are important aspects in the emergence of a stable bacterial community at the end of development. PMID:23344242

  13. Bacterial colonization of Hydra hatchlings follows a robust temporal pattern.

    PubMed

    Franzenburg, Sören; Fraune, Sebastian; Altrock, Philipp M; Künzel, Sven; Baines, John F; Traulsen, Arne; Bosch, Thomas C G

    2013-04-01

    Animals are colonized by complex bacterial communities. The processes controlling community membership and influencing the establishment of the microbial ecosystem during development are poorly understood. Here we aimed to explore the assembly of bacterial communities in Hydra with the broader goal of elucidating the general rules that determine the temporal progression of bacterial colonization of animal epithelia. We profiled the microbial communities in polyps at various time points after hatching in four replicates. The composition and temporal patterns of the bacterial communities were strikingly similar in all replicates. Distinct features included high diversity of community profiles in the first week, a remarkable but transient adult-like profile 2 weeks after hatching, followed by progressive emergence of a stable adult-like pattern characterized by low species diversity and the preponderance of the Betaproteobacterium Curvibacter. Intriguingly, this process displayed important parallels to the assembly of human fecal communities after birth. In addition, a mathematical modeling approach was used to uncover the organizational principles of this colonization process, suggesting that both, local environmental or host-derived factor(s) modulating the colonization rate, as well as frequency-dependent interactions of individual bacterial community members are important aspects in the emergence of a stable bacterial community at the end of development. PMID:23344242

  14. Finding Spatio-Temporal Patterns in Earth Science Data * Pang-Ning Tan+

    E-print Network

    Kumar, Vipin

    1 Finding Spatio-Temporal Patterns in Earth Science Data * Pang-Ning Tan+ Michael Steinbach+ Vipin-temporal patterns from Earth Science data. The data consists of time series measurements for various Earth science of the spatio-temporal issues. Earth Science data has strong seasonal components that need to be removed prior

  15. Biodiversity, productivity and the temporal stability of productivity: patterns and processes

    E-print Network

    Wilsey, Brian J.

    , species interactions can promote biodiversity and ecosystem services. Keywords Biodiversity­ecosystemLETTER Biodiversity, productivity and the temporal stability of productivity: patterns. Additionally, we tested whether biodiversity, productivity and temporal stability were similarly influenced

  16. Acoustic sleepiness detection: framework and validation of a speech-adapted pattern recognition approach.

    PubMed

    Krajewski, Jarek; Batliner, Anton; Golz, Martin

    2009-08-01

    This article describes a general framework for detecting sleepiness states on the basis of prosody, articulation, and speech-quality-related speech characteristics. The advantages of this automatic real-time approach are that obtaining speech data is nonobstrusive and is free from sensor application and calibration efforts. Different types of acoustic features derived from speech, speaker, and emotion recognition were employed (frame-level-based speech features). Combing these features with high-level contour descriptors, which capture the temporal information of frame-level descriptor contours, results in 45,088 features per speech sample. In general, the measurement process follows the speech-adapted steps of pattern recognition: (1) recording speech, (2) preprocessing, (3) feature computation (using perceptual and signal-processing-related features such as, e.g., fundamental frequency, intensity, pause patterns, formants, and cepstral coefficients), (4) dimensionality reduction, (5) classification, and (6) evaluation. After a correlation-filter-based feature subset selection employed on the feature space in order to find most relevant features, different classification models were trained. The best model-namely, the support-vector machine-achieved 86.1% classification accuracy in predicting sleepiness in a sleep deprivation study (two-class problem, N=12; 01.00-08.00 a.m.). PMID:19587194

  17. Temporal classification of Drosophila segmentation gene expression patterns by the multi-valued neural

    E-print Network

    Aizenberg, Igor

    Temporal classification of Drosophila segmentation gene expression patterns by the multi for detecting the age of an embryo on the basis of knowledge about its gene expression patterns. In this paper we perform temporal classification of confocal images of expression patterns of genes controlling

  18. Temporal patterns in adult salmon migration timing across southeast Alaska.

    PubMed

    Kovach, Ryan P; Ellison, Stephen C; Pyare, Sanjay; Tallmon, David A

    2015-05-01

    Pacific salmon migration timing can drive population productivity, ecosystem dynamics, and human harvest. Nevertheless, little is known about long-term variation in salmon migration timing for multiple species across broad regions. We used long-term data for five Pacific salmon species throughout rapidly warming southeast Alaska to describe long-term changes in salmon migration timing, interannual phenological synchrony, relationships between climatic variation and migratory timing, and to test whether long-term changes in migration timing are related to glaciation in headwater streams. Temporal changes in the median date of salmon migration timing varied widely across species. Most sockeye populations are migrating later over time (11 of 14), but pink, chum, and especially coho populations are migrating earlier than they did historically (16 of 19 combined). Temporal trends in duration and interannual variation in migration timing were highly variable across species and populations. The greatest temporal shifts in the median date of migration timing were correlated with decreases in the duration of migration timing, suggestive of a loss of phenotypic variation due to natural selection. Pairwise interannual correlations in migration timing varied widely but were generally positive, providing evidence for weak region-wide phenological synchrony. This synchrony is likely a function of climatic variation, as interannual variation in migration timing was related to climatic phenomenon operating at large- (Pacific decadal oscillation), moderate- (sea surface temperature), and local-scales (precipitation). Surprisingly, the presence or the absence of glaciers within a watershed was unrelated to long-term shifts in phenology. Overall, there was extensive heterogeneity in long-term patterns of migration timing throughout this climatically and geographically complex region, highlighting that future climatic change will likely have widely divergent impacts on salmon migration timing. Although salmon phenological diversity will complicate future predictions of migration timing, this variation likely acts as a major contributor to population and ecosystem resiliency in southeast Alaska. PMID:25482609

  19. Spatial and Temporal Patterns of Eastern Australia Subtropical Coral Communities

    PubMed Central

    Dalton, Steven J.; Roff, George

    2013-01-01

    Despite increases in the frequency and intensity of disturbances on coral reefs over the past few decades, the response of subtropical coral assemblages to climate change is poorly understood. To address this knowledge gap on Australian reefs and provide a baseline for future comparisons, we quantified spatial (10-100’s of kilometres) and temporal (decadal) patterns of benthic assemblages across a latitudinal gradient along the east Australian coastline (23.5° S to 31.5° S). Benthic community composition was quantified at six locations from the southern Great Barrier Reef, Queensland (Heron Reef, 23.5° S, 152° E) to northern New South Wales (31° S, 153.1° E) and at Lord Howe Island (31.5° S, 159.1° E). Our results indicate significant latitudinal differences in benthic assemblages, while community composition at some sites was more similar to those hundreds of kilometres away than to that of neighbouring reefs. A general trend was observed with decreasing cover of Acroporidae with increasing latitude, corresponding with an increasing cover of Pocilloporidae and Dendrophylliidae. Heron Reef comprised a high proportion of Acropora corals (43% total coral cover) and coralline algae (44%). In contrast, high-latitude reefs were dominated by mixed coral assemblages (0-52%) and high macroalgal cover (16-27%). Decadal comparisons of high-latitude reefs showed regional stability of benthic assemblages (9 out of 11 assemblages remained stable at > 75% similarity), during a period of warming oceans (0.15-0.24°C per decade). Such temporal stability suggests that eastern Australian subtropical communities may be more resistant than tropical reef communities that have experienced assembly shifts caused by perturbations associated with recent global climate change. Despite the clear differences in the structure of coral assemblages evident in our spatial surveys, we suggest that the temporal stability of high-latitude reefs may provide a limited refuge for tropical coral populations in an increasingly uncertain future. PMID:24058705

  20. Quantifying temporal and spatial scales and patterns in experiments

    NASA Astrophysics Data System (ADS)

    Reitz, M. D.; Lajeunesse, E.; Limare, A.; Devauchelle, O.; Metivier, F.; Jerolmack, D. J.

    2011-12-01

    The study of landscape evolution often meets with the difficulty of characterizing systems with data of limited temporal or spatial resolution, where boundary conditions may also be poorly constrained. Experiments can provide a useful testing ground for the development of reliable methods of quantification, and experimental delineation of the scales associated with system processes can also inform the translation between experimental and natural systems. We present our approach to quantifying the driving processes in experimental geomorphic systems by describing the methods that have proven useful in our work, with examples from two sets of experiments. In the primary set of experiments, braided rivers are studied using repeat three-dimensional topography scans, obtained through the novel use of an optical technique, which will also be briefly described. Braided rivers provide a particularly powerful example of the usefulness of experiments in elucidating patterns and order in systems which at first glance may seem too complex to be amenable to process-oriented description. Metrics used in quantifying the braided rivers are separated into those that describe unit processes such as channel geometry organization, timescales of channel movement, and bifurcation stability, and those that describe bulk system statistics of the evolving landscape and the self-organizing number and spacing of its channels. We will also draw a few examples from a second set of experiments, in which alluvial fans are studied primarily through two-dimensional image processing, with many methods similar to those used for the braided rivers. In the fan experiments, examples of measured quantities include metrics of the memory of channel locations, the manner of channel movement, and shoreline growth trends. Dominant spatial and temporal scales emerge, which we can relate to fan dynamics. Our presented methods allow us to measure intrinsic system spatial and temporal scales that provide keys to understanding the driving processes and their hierarchies. These methods are useful generally and could be applied to the quantification of a range of natural or experimental systems.

  1. Spatio-Temporal Pattern of Saturn's Equatorial Oscillation

    NASA Technical Reports Server (NTRS)

    Flasar, F. M.; Schnider, P. J.; Marouf, E. A.; McGhee, C. A.; Kliore, A. J.; Rappaport, N. J.

    2010-01-01

    Recent ground-based and Cassini CIRS thermal-infrared data have characterized the spatial and temporal characteristics of an equatorial oscillation in the middle atmosphere of Saturn above the 100-mbar level. The CIRS data [I] indicated a pattern of warm and cold anomalies near the equator, stacked vertically in alternating fashion. The ground-based observations s2, although not having the altitude range or vertical resolution of the CIRS observations, covered several years and indicated an oscillation cycle of approx.15 years, roughly half of Saturn's year. In Earth's middle atmosphere, both the quasi-biennial (approx.26 months) and semi-annual equatorial oscillations have been extensively observed and studied (see e.g., [3]), These exhibit a pattern of alternating warmer and cooler zonal-mean temperatures with altitude, relative to those at subtropical latitudes. Consistent with the thermal wind equation, this is also associated with an alternating pattern of westerly and easterly zonal winds. Moreover, the pattern of winds and temperatures descends with time. Momentum deposition by damped vertically propagating waves is thought to play a key role m forcing both types of oscillation, and it can plausibly account for the descent. Here we report the direct observation of this descent in Saturn's equatorial atmosphere from Cassini radio occultation soundings in 2005 and 2009. The retrieved temperatures are consistent with a descent of 0.7 x the pressure scale height. The descent rate is related to the magnitude of the wave forcing, radiative damping, and induced meridional circulations. We discuss possible implications.

  2. Statistical methods for investigating quiescence and other temporal seismicity patterns

    USGS Publications Warehouse

    Matthews, M.V.; Reasenberg, P.A.

    1988-01-01

    We propose a statistical model and a technique for objective recognition of one of the most commonly cited seismicity patterns:microearthquake quiescence. We use a Poisson process model for seismicity and define a process with quiescence as one with a particular type of piece-wise constant intensity function. From this model, we derive a statistic for testing stationarity against a 'quiescence' alternative. The large-sample null distribution of this statistic is approximated from simulated distributions of appropriate functionals applied to Brownian bridge processes. We point out the restrictiveness of the particular model we propose and of the quiescence idea in general. The fact that there are many point processes which have neither constant nor quiescent rate functions underscores the need to test for and describe nonuniformity thoroughly. We advocate the use of the quiescence test in conjunction with various other tests for nonuniformity and with graphical methods such as density estimation. ideally these methods may promote accurate description of temporal seismicity distributions and useful characterizations of interesting patterns. ?? 1988 Birkha??user Verlag.

  3. Psychological distress through immigration: the two-phase temporal pattern?

    PubMed

    Ritsner, M; Ponizovsky, A

    1999-01-01

    A large community sample, cross-sectional and in part longitudinal design, and comparison groups was used to determine the timing of psychological distress among immigrants. A total of 2,378 adult immigrants from the former Soviet Union to Israel completed the self-administered questionnaire Talbieh Brief Distress Inventory. The aggregate levels of distress and six psychological symptoms--obsessiveness, hostility, interpersonal sensitivity, depression, anxiety, and paranoid ideation--were compared at 20 intervals covering 1 to 60 months after resettlement. The level of psychological distress was significantly higher in the immigrants than that of Israeli natives but not in the potential immigrant controls. A two-phase temporal pattern of development of psychological distress was revealed consisting of escalation and reduction phases. The escalation phase was characterized by an increase in distress levels until the 27th month after arrival (a peak) and the reduction phase led to a decline returning to normal levels. The 1-month prevalence rate was 15.6% for the total sample, and for highly distressed subjects it reached 24% at the 27th month after arrival, and it declined to 4% at the 44th month. The time pattern of distress shared males and females, married and divorced/widowed (but not singles), as well as subjects of all age groups (except for immigrants in their forties). The two-phase pattern of distress obtained according to cross-sectional data was indirectly confirmed through a longitudinal way. Claims of early euphoric or distress-free period followed by mental health crisis frequently referred to in the literature on migration was not supported by this study. PMID:10443255

  4. Conversion of sound radiation pattern via gradient acoustic metasurface with space-coiling structure

    NASA Astrophysics Data System (ADS)

    Yuan, Baoguo; Cheng, Ying; Liu, Xiaojun

    2015-02-01

    We designed, fabricated, and experimentally demonstrated a gradient acoustic metasurface to manipulate sound radiation patterns. The gradient metasurface is constructed on the basis of a coiling-up space in a tunable interdigitated structure, which exhibits relative refractive index in a discretized classic hyperbolic secant profile. Capable of generating secondary sound sources with desired gradient phase shifts, the metasurface shows the ability of controlling sound radiation such as by cylindrical-to-plane-wave conversion, plane wave focusing, and effective tunable acoustic negative refraction. Owing to its deep-subwavelength thickness, the metasurface may reduce the size of acoustic devices and offer potential applications in imaging and scanning systems.

  5. Innovations in motoneuron synchrony drive rapid temporal modulations in vertebrate acoustic signaling

    PubMed Central

    Chagnaud, Boris P.; Zee, Michele C.; Baker, Robert

    2012-01-01

    Rapid temporal modulation of acoustic signals among several vertebrate lineages has recently been shown to depend on the actions of superfast muscles. We hypothesized that such fast events, known to require synchronous activation of muscle fibers, would rely on motoneuronal properties adapted to generating a highly synchronous output to sonic muscles. Using intracellular in vivo recordings, we identified a suite of premotor network inputs and intrinsic motoneuronal properties synchronizing the oscillatory-like, simultaneous activation of superfast muscles at high gamma frequencies in fish. Motoneurons lacked spontaneous activity, firing synchronously only at the frequency of premotor excitatory input. Population-level motoneuronal output generated a spike-like, vocal nerve volley that directly determines muscle contraction rate and, in turn, natural call frequency. In the absence of vocal output, motoneurons showed low excitability and a weak afterhyperpolarization, leading to rapid accommodation in firing rate. By contrast, vocal activity was accompanied by a prominent afterhyperpolarization, indicating a dependency on network activity. Local injection of a GABAA receptor antagonist demonstrated the necessity of electrophysiologically and immunohistochemically confirmed inhibitory GABAergic input for motoneuronal synchrony and vocalization. Numerous transneuronally labeled motoneurons following single-cell neurobiotin injection together with electrophysiological collision experiments confirmed gap junctional coupling, known to contribute to synchronous activity in other neural networks. Motoneuronal synchrony at the premotor input frequency was maintained during differential recruitment of variably sized motoneurons. Differential motoneuron recruitment led, however, to amplitude modulation (AM) of vocal output and, hence, natural call AM. In summary, motoneuronal intrinsic properties, in particular low excitability, predisposed vocal motoneurons to the synchronizing influences of premotor inputs to translate a temporal input code into a coincident and extremely synchronous, but variable-amplitude, output code. We propose an analogous suite of neuronal properties as a key innovation underlying similarly rapid acoustic events observed among amphibians, reptiles, birds, and mammals. PMID:22423004

  6. Spatial and temporal patterns in modeled particle transport to estuarine habitat with comparisons to larval fish

    E-print Network

    Jackson, George

    in suitable settlement habitat. Some studies suggest that larval supply is determined by passive transport examining spatial and temporal transport patterns of fish larvae within bays. Using a passive particleSpatial and temporal patterns in modeled particle transport to estuarine habitat with comparisons

  7. QueryMarvel: A visual query language for temporal patterns using comic strips

    Microsoft Academic Search

    Jing Jin; Pedro A. Szekely

    2009-01-01

    In many domains, decision makers want to find and understand patterns of events as these patterns often give insight into the causal relationships among events. Current systems to specify patterns are either too difficult to use or only support simple patterns. We present QueryMarvel, an interactive visual query environment that allows ordinary users to easily and efficiently specify complex temporal

  8. Spatial and Temporal Patterns of Global Onshore Wind Speed Distribution

    SciTech Connect

    Zhou, Yuyu; Smith, Steven J.

    2013-09-09

    Wind power, a renewable energy source, can play an important role in electrical energy generation. Information regarding wind energy potential is important both for energy related modeling and for decision-making in the policy community. While wind speed datasets with high spatial and temporal resolution are often ultimately used for detailed planning, simpler assumptions are often used in analysis work. An accurate representation of the wind speed frequency distribution is needed in order to properly characterize wind energy potential. Using a power density method, this study estimated global variation in wind parameters as fitted to a Weibull density function using NCEP/CFSR reanalysis data. The estimated Weibull distribution performs well in fitting the time series wind speed data at the global level according to R2, root mean square error, and power density error. The spatial, decadal, and seasonal patterns of wind speed distribution were then evaluated. We also analyzed the potential error in wind power estimation when a commonly assumed Rayleigh distribution (Weibull k = 2) is used. We find that the assumption of the same Weibull parameter across large regions can result in substantial errors. While large-scale wind speed data is often presented in the form of average wind speeds, these results highlight the need to also provide information on the wind speed distribution.

  9. Spatial and temporal gene expression patterns occur during corm development.

    PubMed Central

    de Castro, L A; Carneiro, M; Neshich, D de C; de Paiva, G R

    1992-01-01

    We investigated gene expression patterns that occur during taro corm development. Two-dimensional gel electrophoresis identified several different prevalent proteins that accumulate during corm development. Microsequencing studies indicated that some of these proteins are related to taste-modifying proteins, such as curculin and miraculin, and proteins found in other storage organs, such as sporamin and the Kunitz trypsin inhibitor. A curculin-encoding cDNA clone, designated as TC1, was identified that corresponds to a highly prevalent 1-kb corm mRNA. The TC1 mRNA accumulates during corm development, is more prevalent in corm apical than basal regions, and is either absent, or present at low concentrations, in other vegetative organs such as the leaf and root. In situ hybridization experiments showed that the TC1 mRNA is highly concentrated in corm storage parenchyma cells and is absent, or present in reduced concentrations, in other corm cells and tissues. Our results show that corm development is associated with the differentiation of specialized cells and tissues, and that these differentiation events are coupled with the temporal and spatial expression of corm-specific genes. PMID:1467653

  10. Spatial and temporal gene expression patterns occur during corm development.

    PubMed

    de Castro, L A; Carneiro, M; Neshich, D de C; de Paiva, G R

    1992-12-01

    We investigated gene expression patterns that occur during taro corm development. Two-dimensional gel electrophoresis identified several different prevalent proteins that accumulate during corm development. Microsequencing studies indicated that some of these proteins are related to taste-modifying proteins, such as curculin and miraculin, and proteins found in other storage organs, such as sporamin and the Kunitz trypsin inhibitor. A curculin-encoding cDNA clone, designated as TC1, was identified that corresponds to a highly prevalent 1-kb corm mRNA. The TC1 mRNA accumulates during corm development, is more prevalent in corm apical than basal regions, and is either absent, or present at low concentrations, in other vegetative organs such as the leaf and root. In situ hybridization experiments showed that the TC1 mRNA is highly concentrated in corm storage parenchyma cells and is absent, or present in reduced concentrations, in other corm cells and tissues. Our results show that corm development is associated with the differentiation of specialized cells and tissues, and that these differentiation events are coupled with the temporal and spatial expression of corm-specific genes. PMID:1467653

  11. The temporal patterns of disease severity and prevalence in schistosomiasis

    NASA Astrophysics Data System (ADS)

    Ciddio, Manuela; Mari, Lorenzo; Gatto, Marino; Rinaldo, Andrea; Casagrandi, Renato

    2015-03-01

    Schistosomiasis is one of the most widespread public health problems in the world. In this work, we introduce an eco-epidemiological model for its transmission and dynamics with the purpose of explaining both intra- and inter-annual fluctuations of disease severity and prevalence. The model takes the form of a system of nonlinear differential equations that incorporate biological complexity associated with schistosome's life cycle, including a prepatent period in snails (i.e., the time between initial infection and onset of infectiousness). Nonlinear analysis is used to explore the parametric conditions that produce different temporal patterns (stationary, endemic, periodic, and chaotic). For the time-invariant model, we identify a transcritical and a Hopf bifurcation in the space of the human and snail infection parameters. The first corresponds to the occurrence of an endemic equilibrium, while the latter marks the transition to interannual periodic oscillations. We then investigate a more realistic time-varying model in which fertility of the intermediate host population is assumed to seasonally vary. We show that seasonality can give rise to a cascade of period-doubling bifurcations leading to chaos for larger, though realistic, values of the amplitude of the seasonal variation of fertility.

  12. The temporal patterns of disease severity and prevalence in schistosomiasis.

    PubMed

    Ciddio, Manuela; Mari, Lorenzo; Gatto, Marino; Rinaldo, Andrea; Casagrandi, Renato

    2015-03-01

    Schistosomiasis is one of the most widespread public health problems in the world. In this work, we introduce an eco-epidemiological model for its transmission and dynamics with the purpose of explaining both intra- and inter-annual fluctuations of disease severity and prevalence. The model takes the form of a system of nonlinear differential equations that incorporate biological complexity associated with schistosome's life cycle, including a prepatent period in snails (i.e., the time between initial infection and onset of infectiousness). Nonlinear analysis is used to explore the parametric conditions that produce different temporal patterns (stationary, endemic, periodic, and chaotic). For the time-invariant model, we identify a transcritical and a Hopf bifurcation in the space of the human and snail infection parameters. The first corresponds to the occurrence of an endemic equilibrium, while the latter marks the transition to interannual periodic oscillations. We then investigate a more realistic time-varying model in which fertility of the intermediate host population is assumed to seasonally vary. We show that seasonality can give rise to a cascade of period-doubling bifurcations leading to chaos for larger, though realistic, values of the amplitude of the seasonal variation of fertility. PMID:25833443

  13. Spatio-temporal patterns of precipitation in Serbia

    NASA Astrophysics Data System (ADS)

    Gocic, Milan; Trajkovic, Slavisa

    2014-08-01

    The monthly precipitation data from 29 synoptic stations for the period 1946-2012 were analyzed using a number of different multivariate statistical analysis methods to investigate the spatial variability and temporal patterns of precipitation across Serbia. R-mode principal component analysis was used to study the spatial variability of the precipitation. Three distinct sub-regions were identified by applying the agglomerative hierarchical cluster analysis to the two component scores: C1 includes the north and the northeast part of Serbia, while C2 includes the western part of Central Serbia and southwestern part of Serbia and C3 includes central, east, south and southeast part of Serbia. The analysis of the identified sub-regions indicated that the monthly and seasonal precipitation in sub-region C2 had the values above average, while C1 and C3 had the precipitation values under average. The analysis of the linear trend of the mean annual precipitation showed an increasing trend for the stations located in Serbia and three sub-regions. From the result of this analysis, one can plan land use, water resources and agricultural production in the region.

  14. Numerical simulations of acoustic cavitation noise with the temporal fluctuation in the number of bubbles.

    PubMed

    Yasui, Kyuichi; Tuziuti, Toru; Lee, Judy; Kozuka, Teruyuki; Towata, Atsuya; Iida, Yasuo

    2010-02-01

    Numerical simulations of cavitation noise have been performed under the experimental conditions reported by Ashokkumar et al. (2007) [26]. The results of numerical simulations have indicated that the temporal fluctuation in the number of bubbles results in the broad-band noise. "Transient" cavitation bubbles, which disintegrate into daughter bubbles mostly in a few acoustic cycles, generate the broad-band noise as their short lifetimes cause the temporal fluctuation in the number of bubbles. Not only active bubbles in light emission (sonoluminescence) and chemical reactions but also inactive bubbles generate the broad-band noise. On the other hand, "stable" cavitation bubbles do not generate the broad-band noise. The weaker broad-band noise from a low-concentration surfactant solution compared to that from pure water observed experimentally by Ashokkumar et al. is caused by the fact that most bubbles are shape stable in a low-concentration surfactant solution due to the smaller ambient radii than those in pure water. For a relatively high number density of bubbles, the bubble-bubble interaction intensifies the broad-band noise. Harmonics in cavitation noise are generated by both "stable" and "transient" cavitation bubbles which pulsate nonlinearly with the period of ultrasound. PMID:19751988

  15. Histopathology and growth pattern of cystic acoustic neuromas.

    PubMed

    Charabi, S; Klinken, L; Tos, M; Thomsen, J

    1994-11-01

    In a series of 571 acoustic neuromas, 23 were identified as cystic tumors. An immunohistochemical study including nervous system-associated protein (S-100), glial fibrillary acidic protein (GFAP), neurofilament protein (NF), laminin, fibronectin, vimentin, factor VIII (von Willebrand factor)-related antigen, and the nuclear antibody Ki-67 was performed. The cyst walls contained numerous S-100-positive fibrils distributed throughout the whole extent of the walls. Laminin, fibronectin, and vimentin were predominantly located around the vessel walls, factor VIII was found inside the vessels. GFAP-positive lamellae occurred in 50% of the cases near the surface of the cyst walls. Ki-67 is an antigen associated with cell proliferation. The density of Ki-67-positive cells was found to be 36 times lower in 16 noncystic controls than in the 23 cystic neuromas, indicating that the increase in tumor size in cystic acoustic neuromas may be caused by expansion of the cysts and not by an actual increase in the growth rate of the tumor cells. The data achieved in this series may contribute to better planning of the surgical approach. Because of the risk of sudden expansion of cystic elements, a wait-and-see policy should not be applied to patients with cystic acoustic neuromas. PMID:7968163

  16. Temporal motifs reveal homophily, gender-specific patterns and group talk in mobile communication networks

    E-print Network

    Kovanen, Lauri; Kertész, János; Saramäki, Jari

    2013-01-01

    Electronic communication records provide detailed information about temporal aspects of human interaction. Previous studies have shown that individuals' communication patterns have complex temporal structure, and that this structure has system-wide effects. In this paper we use mobile phone records to show that interaction patterns involving multiple individuals have non-trivial temporal structure that cannot be deduced from a network presentation where only interaction frequencies are taken into account. We apply a recently introduced method, temporal motifs, to identify interaction patterns in a temporal network where nodes have additional attributes such as gender and age. We then develop a null model that allows identifying differences between various types of nodes so that these differences are independent of the network based on interaction frequencies. We find gender-related differences in communication patters, and show the existence of temporal homophily, the tendency of similar individuals to partic...

  17. Control of Spatial-Temporal Congested Traffic Patterns at Highway Bottlenecks

    Microsoft Academic Search

    Boris S. Kerner

    2003-01-01

    A microscopic theory of control of spatial-temporal congested traffic pattern\\u000aat freeway bottlenecks is presented. Based on empirical spatial-temporal\\u000afeatures of congested patterns at freeway bottlenecks which have recently been\\u000afound, different control strategies for prevention or reducing of the patterns\\u000aare simulated and compared. The studied control strategies include the on-ramp\\u000ametering with feedback and automatic cruise control (ACC)

  18. Spatial and temporal patterns of subtidal and intertidal crabs excursions

    NASA Astrophysics Data System (ADS)

    Silva, A. C. F.; Boaventura, D. M.; Thompson, R. C.; Hawkins, S. J.

    2014-01-01

    Highly mobile predators such as fish and crabs are known to migrate from the subtidal zone to forage in the intertidal zone at high-tide. The extent and variation of these habitat linking movements along the vertical shore gradient have not been examined before for several species simultaneously, hence not accounting for species interactions. Here, the foraging excursions of Carcinus maenas (L.), Necora puber (Linnaeus, 1767) and Cancer pagurus (Linnaeus, 1758) were assessed in a one-year mark-recapture study on two replicated rocky shores in southwest U.K. A comparison between the abundance of individuals present on the shore at high-tide with those present in refuges exposed at low-tide indicated considerable intertidal migration by all species, showing strong linkage between subtidal and intertidal habitats. Estimates of population size based on recapture of marked individuals indicated that an average of ~ 4000 individuals combined for the three crab species, can be present on the shore during one tidal cycle. There was also a high fidelity of individuals and species to particular shore levels. Underlying mechanisms for these spatial patterns such as prey availability and agonistic interactions are discussed. Survival rates were estimated using the Cormack-Jolly-Seber model from multi-recapture analysis and found to be considerably high with a minimum of 30% for all species. Growth rates were found to vary intraspecifically with size and between seasons. Understanding the temporal and spatial variations in predation pressure by crabs on rocky shores is dependent on knowing who, when and how many of these commercially important crab species depend on intertidal foraging. Previous studies have shown that the diet of these species is strongly based on intertidal prey including key species such as limpets; hence intertidal crab migration could be associated with considerable impacts on intertidal assemblages.

  19. Spatial and Temporal Patterns of Aerosol-Cloud Interactions

    NASA Astrophysics Data System (ADS)

    Fuchs, Julia; Cermak, Jan

    2014-05-01

    This study determines the spatial and temporal distribution of regions with frequent aerosol-cloud interactions (aci) and identifies their meteorological determinants based on CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) and ECMWF (European Centre for Medium-Range Weather Forecasts) data products. Atmospheric aerosols influence the microphysical structure of clouds, while both also respond to meteorological conditions. The potential radiative adjustments to changes in a cloud system associated with aerosol-cloud interactions are grouped and termed as effective radiative forcing due to aerosol-cloud interactions (ERFaci). It is difficult to distinguish, to what extent radiative forcing and precipitation patterns of clouds are a result of cloud feedbacks to aerosols or the existing meteorological conditions. A complete understanding of aerosol-cloud-meteorology interactions is crucial as the uncertainty range of ERFaci in climate change modeling could be significantly reduced. In the present study it is suggested that presence of hydrated aerosols is an implication for aci. Knowledge of their vertical and horizontal distribution and frequency over the globe would be important for understanding ERFaci. To identify regions with aerosol-cloud transitions the CAD score (cloud-aerosol discrimination) of the CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization) instrument on the CALIPSO satellite is used. It separates aerosols and clouds according to the probability distribution functions of 5 parameters (attenuated backscatter, total color ratio, volume depolarization ratio, altitude and latitude) and assigns the likelihood of cloud or aerosol presence. This parameter is used to calculate relative frequencies of aci on a global scale from 2006 to 2013.

  20. Sound temporal envelope and time-patterns of activity in the human auditory pathway : an fMRI study

    E-print Network

    Harms, Michael Patrick, 1972-

    2002-01-01

    The temporal envelope of sound strongly influences the intelligibility of speech, pattern analysis, and the grouping of sequential stimuli. This thesis examined the coding of sound temporal envelope in the time-patterns ...

  1. Acoustics and sociolinguistics: Patterns of communication in hearing impairing classrooms

    NASA Astrophysics Data System (ADS)

    McKellin, William; Shahin, Kimary; Jamieson, Janet; Hodgson, Murray; Pichora-Fuller, Kathleen

    2005-04-01

    In elementary school classes, noise during student led activities is often taken as evidence of successful interaction and learning. In this complex social environment of elementary school classrooms, acquisition of complex language and social skills-the focus of activities in early education-is expected to take place in hearing-hostile environments. Communication and language processing in these contexts requires interactive strategies, discourse forms, and syntactic structures different from the educationally desired forms used in acoustically advantageous environments. Recordings were made of the interaction of groups of students in grades 1-3, 5, and 7 during collaborative group work in their regular classrooms. Each student wore microphones at the ear level and head-mounted video cameras. Each group as a whole was also audio- and videotaped and noise level readings were recorded. Analysis of the acoustical and phonological properties of language heard by each student has demonstrated that the language variety used in these noisy and reverberant settings is similar to that of individuals with hearing impairments. This paper reports similarities between the syntactic structures and pragmatic strategies used by hearing impaired children and normally hearing children in noisy contexts. [Work supported by Peter Wall Institute for Advanced Studies, University of British Columbia.

  2. Acoustic emissions from penny-shaped cracks in glass. I. Radiation pattern and crack orientation

    NASA Astrophysics Data System (ADS)

    Kim, Kwang Yul; Sachse, Wolfgang

    1986-04-01

    In the first part of this paper we describe measurements of the radiation pattern of the acoustic emission (AE) signals emitted when a penny-shaped crack of Mode I type is generated in a glass plate by pressing a rigid conical indenter onto the surface. It is shown that the orientation of a crack determined from the radiation pattern of the emitted AE signals is in agreement to within several degrees with a direct optical determination.

  3. Assessing the value of information in climber's guidebooks to derive spatio-temporal rockfall patterns

    NASA Astrophysics Data System (ADS)

    Temme, A. J. A. M.

    2012-04-01

    Rockfall rates in mountain ranges are expensive to measure over large spatial scales, mainly due to the inaccessibility of mountainous terrain. Existing methods to measure rockfall include acoustic methods (listening to the rock's impact or creation by frost weathering) , spectral methods (looking at the colour of mountain faces to determine their freshness and by extension the time since last rockfall) and volumetric methods (measuring the volume that fell). These methods, especially in combination, have allowed researchers to quantitatively derive rates (and distribution of rates over time) of rockfall for several well studied locations. However, the small spatial support of these methods means that results are only valid for small well-studied locations. This is a problem when we want to derive baseline information on rockfall rates over entire mountain chains and ranges - which is important to study their temporal distribution and their relation with climate change. This contribution explores the potential of information contained in climber's guidebooks to derive qualitative rockfall rates with large spatial and temporal coverage. Climber's guidebooks have been published since the early 1900's, giving prospective mountaineers strongly codified information about routes and conditions expected along the way. The information about the looseness of rocks, which is clearly important for climbers from a safety perspective, may also be useful to link to rockfall rates. I have used a series of guidebooks published at irregular intervals for the Bernese Oberland in Switzerland to study the change in descriptions of looseness of rocks for a number of famous climbing routes. These routes were selected because of the opportunity to complement information in guidebooks with other (visual and written) sources of information. Results indicate that descriptions of looseness of rock can be used to derive a qualitative pattern of rockfall, especially over larger spatial scales. The value of the information is also valuable as a link to temporal changes in rockfall rates, but this use is hampered by the fact that text is sometimes copied between successive guidebooks without a stringent reassessment of actual conditions on the route.

  4. General asymmetric neutral networks and structure design by genetic algorithms: A learning rule for temporal patterns

    SciTech Connect

    Bornholdt, S. [Heidelberg Univ., (Germany). Inst., fuer Theoretische Physik; Graudenz, D. [Lawrence Berkeley Lab., CA (United States)

    1993-07-01

    A learning algorithm based on genetic algorithms for asymmetric neural networks with an arbitrary structure is presented. It is suited for the learning of temporal patterns and leads to stable neural networks with feedback.

  5. Speech comprehension is correlated with temporal response patterns recorded from auditory cortex

    E-print Network

    Ahissar, Ehud

    Speech comprehension is correlated with temporal response patterns recorded from auditory cortex, Hebrew University, Jerusalem 91905, Israel; ¶Department of Speech Technology, Institute for Language and Speech Processing, 15125 Maroussi, Greece; **The Keck Center for Integrative Neurosciences, University

  6. Temporal Patterns of Medications Dispensed to Children and Adolescents in a National Insured Population

    E-print Network

    Olson, Karen L.

    This study aimed to comprehensively describe prevalence and temporal dispensing patterns for medications prescribed to children and adolescents in the United States. Participants were 1.6 million children (49% female) under ...

  7. Spatio-temporal foraging patterns of a giant zooplanktivore, the leatherback turtle

    Microsoft Academic Search

    Sabrina Fossette; Victoria J. Hobson; Charlotte Girard; Beatriz Calmettes; Philippe Gaspar; Jean-Yves Georges; Graeme C. Hays

    2010-01-01

    Understanding food web functioning through the study of natural bio-indicators may constitute a valuable and original approach. In the context of jellyfish proliferation in many overexploited marine ecosystems studying the spatio-temporal foraging patterns of the giant “jellyvore” leatherback turtle turns out to be particularly relevant. Here we analyzed long-term tracking data to assess spatio-temporal foraging patterns in 21 leatherback turtles

  8. Experimental validation of acoustic radiation force induced shear wave interference patterns.

    PubMed

    Hoyt, Kenneth; Hah, Zaegyoo; Hazard, Chris; Parker, Kevin J

    2012-01-01

    A novel elasticity imaging system founded on the use of acoustic radiation forces from a dual beam arrangement to generate shear wave interference patterns is described. Acquired pulse-echo data and correlation-based techniques were used to estimate the resultant deformation and to visualize tissue viscoelastic response. The use of normal versus axicon focal configurations was investigated for effects on shear wave generation. Theoretical models were introduced and shown in simulation to accurately predict shear wave propagation and interference pattern properties. In a tissue-mimicking phantom, experimental results are in congruence with theoretical predictions. Using dynamic acoustic radiation force excitation, results confirm that shear wave interference patterns can be produced remotely in a particular tissue region of interest (ROI). Overall, preliminary results are encouraging and the system described may prove feasible for interrogating the viscoelastic properties of normal and diseased tissue types. PMID:22127377

  9. Pattern recognition of Landsat data based upon temporal trend analysis

    NASA Technical Reports Server (NTRS)

    Engvall, J. L.; Tubbs, J. D.; Holmes, Q. A.

    1977-01-01

    The Delta Classifier defined as an agricultural crop classification scheme employing a temporal trend procedure is applied to more than 100 different Landsat data sets collected during the 1974-1975 growing season throughout the major wheat-producing regions of the United States. The classification approach stresses examination of temporal trends of the Landsat mean vectors of crops in the absence of corresponding ground truth information. It is shown that the resulting classifications compare favorably to ground truth estimates for wheat proportion in those cases where ground truth is available, and that the temporal trend procedure yields estimates of the wheat proportion that are comparable to the best results from maximum likelihood classification with photointerpreter-defined training fields.

  10. Spatio-temporal patterns of Campylobacter colonization in Danish broilers.

    PubMed

    Chowdhury, S; Themudo, G E; Sandberg, M; Ersbøll, A K

    2013-05-01

    Despite a number of risk-factor studies in different countries, the epidemiology of Campylobacter colonization in broilers, particularly spatial dependencies, is still not well understood. A series of analyses (visualization and exploratory) were therefore conducted in order to obtain a better understanding of the spatial and temporal distribution of Campylobacter in the Danish broiler population. In this study, we observed a non-random temporal occurrence of Campylobacter, with high prevalence during summer and low during winter. Significant spatio-temporal clusters were identified in the same areas in the summer months from 2007 to 2009. Range of influence between broiler farms were estimated at distances of 9.6 km and 13.5 km in different years. Identification of areas and time with greater risk indicates variable presence of risk factors with space and time. Implementation of safety measures on farms within high-risk clusters during summer could have an impact in reducing prevalence. PMID:22814565

  11. Detection of Calendar-Based Periodicities of Interval-Based Temporal Patterns

    E-print Network

    Mahanta, Anjana K

    2012-01-01

    We present a novel technique to identify calendar-based (annual, monthly and daily) periodicities of an interval-based temporal pattern. An interval-based temporal pattern is a pattern that occurs across a time-interval, then disappears for some time, again recurs across another time-interval and so on and so forth. Given the sequence of time-intervals in which an interval-based temporal pattern has occurred, we propose a method for identifying the extent to which the pattern is periodic with respect to a calendar cycle. In comparison to previous work, our method is asymptotically faster. We also show an interesting relationship between periodicities across different levels of any hierarchical timestamp (year/month/day, hour/minute/second etc.).

  12. Retrieving controlled motion parameters using two speckle pattern analysis techniques: spatiotemporal correlation and the temporal history speckle pattern.

    PubMed

    Nassif, Rana; Abou Nader, Christelle; Pellen, Fabrice; Le Brun, Guy; Abboud, Marie; Le Jeune, Bernard

    2013-11-01

    This paper presents simulation of speckle activity through controlling a moving plate. We present two procedures to extract the initial movement frequency and amplitude, either through correlation calculus or through processing the temporal history of the speckle pattern. We compare and discuss these two methods in terms of efficiency and the ability to retrieve motion parameters. The correlation technique seems to be more suitable for monitoring biospeckle activity as it provides more reliable parameter estimation than the temporal history of the speckle pattern. The evolution of temporal history of the speckle pattern parameters and their response sensibility with amplitude and frequency variations have been studied and quantified. Briers contrast appears to depend only on movement amplitude, whereas inertia moment varies with amplitude and frequency. PMID:24216659

  13. Discovering Temporal Features and Relations of Activity Patterns

    E-print Network

    Cook, Diane J.

    (ADL) [1] such as taking medication, cooking, eating and sleeping. Assistive technologies such as smart in an activity reminder application or a home automation system. In this paper, we provide a framework mention just a few such applications: - Reminder systems: The discovered temporal information can be used

  14. Spatio-temporal Spike Pattern Classification in Neuromorphic Systems

    E-print Network

    architectures offer an attractive solution for implementing compact efficient sensory-motor neural processing, classify the spatio-temporal information contained in the data, and pro- duce appropriate motor outputs and asynchronous streams of spikes, and spiking multi-neuron chips [5, 6, 7] for implementing state dependent

  15. Spatial Patterns and Temporal Trajectories of the Bog Ground Layer

    E-print Network

    Benscoter, Brian W.

    conditions and initiating succession. How- ever, the successional trajectory of the ground layer community established vegetation plots in 13 bogs and repeatedly monitored them from 2003­2006. We found three phases the first comprehen- sive description of the spatio-temporal post-fire successional trajectory of the bog

  16. Patterns of acoustic variation in Cicada barbara Stål (Hemiptera, Cicadoidea) from the Iberian Peninsula and Morocco.

    PubMed

    Pinto-Juma, G A; Seabra, S G; Quartau, J A

    2008-02-01

    Field recordings of the calling song and of an amplitude modulated signal produced by males of Cicada barbara from North Africa and the Iberian Peninsula were analysed in order to assess the geographical acoustic variation and the potential usefulness of acoustic data in the discrimination of subspecies and populations. Sound recordings were digitized and the frequency and temporal properties of the calls of each cicada were analysed. In all regions studied, peak frequency, quartiles 25, 50 and 75% and syllable rate showed low coefficients of variation suggesting inherent static properties. All frequency variables were correlated with the latitude, decreasing from south to north. In addition, most acoustic variables of the calling song showed significant differences between regions, and PCA and DFA analyses supported a partitioning within this species between Iberian Peninsula+Ceuta and Morocco, corroborating mtDNA data on the same species. Therefore, the subspecific division of C. barbara into C. barbara barbara from Morocco and C. barbara lusitanica from Portugal, Spain and Ceuta finds support from the present acoustic analyses, a result which is also reinforced by molecular markers. PMID:18062838

  17. Seasonal forcing drives spatio-temporal pattern formation in rabies epidemics

    E-print Network

    Seasonal forcing drives spatio-temporal pattern formation in rabies epidemics Niels v. Festenberg1 of rabies dispersal. We reduce an established individual-based high- detail model down to a deterministic of epidemic wave fronts. Keywords: pattern formation, epidemics, rabies, seasonal forcing AMS classification

  18. Spatial and temporal patterns of nitrogen concentrations in pristine and agriculturally-influenced prairie streams

    Microsoft Academic Search

    Melody J. Kemp; Walter K. Dodds

    2001-01-01

    Long-term data on nitrogen chemistry of streams draining Konza Prairie Biological Station (Konza), Kansas were analyzed to assess spatial and temporal patterns and examine the influence of agricultural activity on these patterns. Upland watersheds of Konza are predominantly tallgrass prairies, but agricultural fields and riparian forests border the lower reaches of the streams. We have up to 11 years of

  19. Spatial and temporal patterns of nitrogen concentrations in pristine and agriculturally-influenced prairie streams

    Microsoft Academic Search

    MELODY J. KEMP; WALTER K. DODDS

    2001-01-01

    Long-term data on nitrogen chemistry of streams draining Konza Prairie Biological Station (Konza), Kansas were analyzed to assess spatial and temporal patterns and examine the influence of agricultural activity on these patterns. Upland watersheds of Konza are predom- inantly tallgrass prairies, but agricultural fields and riparian forests border the lower reaches of the streams. We have up to 11 years

  20. Cultural and environmental influences on temporal-spectral development patterns of corn and soybeans

    NASA Technical Reports Server (NTRS)

    Crist, E. P.

    1982-01-01

    A technique for evaluating crop temporal-spectral development patterns is described and applied to the analysis of cropping practices and environmental conditions as they affect reflectance characteristics of corn and soybean canopies. Typical variations in field conditions are shown to exert significant influences on the spectral development patterns, and thereby to affect the separability of the two crops.

  1. Temporal Pattern as a Cue for Species-Specific Calling Song Recognition in Crickets

    Microsoft Academic Search

    Gerald S. Pollack; Ronald R. Hoy

    1979-01-01

    Female crickets can recognize conspecific calling song from its temporal pattern alone. In Teleogryllus oceanicus, the song pattern consists of three classes of interpulse intervals arranged in a stereotyped sequence. Females recognize a model song in which the sequential order of intervals is random. This argues against the hypothesis that recognition results from matching auditory input to an internal template

  2. Finding Temporal Patterns in Noisy Longitudinal Data: A Study in Diabetic

    E-print Network

    Coenen, Frans

    Finding Temporal Patterns in Noisy Longitudinal Data: A Study in Diabetic Retinopathy Vassiliki is a large longitudinal patient database collected as part of a diabetic retinopathy screening programme. The diabetic retinopathy application, the data warehousing and cleaning process, and the frequent pattern

  3. Hemispatial PCA dissociates temporal from parietal ERP generator patterns

    PubMed Central

    Tenke, Craig E.; Kayser, Jürgen; Shankman, Stewart A.; Griggs, Carlye B.; Leite, Paul; Stewart, Jonathan W.; Bruder, Gerard E.

    2008-01-01

    Event-related potentials (31-channel ERPs) were recorded from 38 depressed, unmedicated outpatients and 26 healthy adults (all right-handed) in tonal and phonetic oddball tasks developed to exploit the perceptual challenge of a dichotic stimulation. Tonal nontargets were pairs of complex tones (corresponding to musical notes G and B above middle C) presented simultaneously to each ear (L/R) in an alternating series (G/B or B/G; 2-s fixed SOA). A target tone (note A) replaced one of the pair on 20% of the trials (A/B, G/A, B/A, A/G). Phonetic nontargets were L/R pairs of syllables (/ba/, /da/) with a short voice onset time (VOT), and targets contained a syllable (/ta/) with a long VOT. Subjects responded with a left or right button press to targets (counterbalanced across blocks). Target detection was poorer in patients than controls and for tones than syllables. Reference-free current source densities (CSDs; spherical spline Laplacian) derived from ERP waveforms were simplified and measured using temporal, covariance-based PCA followed by unrestricted Varimax rotation. Target-related N2 sinks and mid-parietal P3 sources were represented by CSD factors peaking at 245 and 440 ms. The P3 source topography included a secondary, left-lateralized temporal lobe maximum for both targets and nontargets. However, a subsequent hemispheric spatiotemporal PCA disentangled temporal lobe N1 and P3 sources as distinct factors. P3 sources were reduced in patients compared with controls, even after using performance as a covariate. Results are consistent with prior reports of P3 reduction in depression and implicate distinct parietal and temporal generators of P3 when using a dichotic oddball paradigm. PMID:17963912

  4. Analysis of Tropical Ice Cloud Spatial and Temporal Patterns

    Microsoft Academic Search

    K. Meyer; P. Yang; G. North; B. Gao

    2005-01-01

    The Moderate-resolution Imaging Spectroradiometers (MODIS) on NASA's Terra and Aqua platforms offer valuable observations of the earth and its atmosphere, facilitating significant research in the atmospheric sciences. Specifically, the implementation of the 1.375-mum water vapor absorption band allows for exclusive investigations of ice clouds (e.g., cirrus clouds). In this study, we perform an analysis of the spatial and temporal trends

  5. Patterns of altered functional connectivity in mesial temporal lobe epilepsy

    PubMed Central

    Pittau, Francesca; Grova, Christophe; Moeller, Friederike; Dubeau, François; Gotman, Jean

    2013-01-01

    Summary Purpose In mesial temporal lobe epilepsy (MTLE) the epileptogenic area is confined to the mesial temporal lobe, but other cortical and subcortical areas are also affected and cognitive and psychiatric impairments are usually documented. Functional connectivity methods are based on the correlation of the blood oxygen level dependent (BOLD) signal between brain regions, which exhibit consistent and reproducible functional networks from resting state data. The aim of this study is to compare functional connectivity of patients with MTLE during the interictal period with healthy subjects. We hypothesize that patients show reduced functional connectivity compared to controls, the interest being to determine which regions show this reduction. Methods We selected electroencephalography–functional magnetic resonance imaging (EEG-fMRI) resting state data without EEG spikes from 16 patients with right and 7 patients with left MTLE. EEG-fMRI resting state data of 23 healthy subjects matched for age, sex, and manual preference were selected as controls. Four volumes of interest in the left and right amygdalae and hippocampi (LA, RA, LH, and RH) were manually segmented in the anatomic MRI of each subject. The averaged BOLD time course within each volume of interest was used to detect brain regions with BOLD signal correlated with it. Group differences between patients and controls were estimated. Key Findings In patients with right MTLE, group difference functional connectivity maps (RMTLE – controls) showed for RA and RH decreased connectivity with the brain areas of the default mode network (DMN), the ventromesial limbic prefrontal regions, and contralateral mesial temporal structures; and for LA and LH, decreased connectivity with DMN and contralateral hippocampus. Additional decreased connectivity was found between LA and pons and between LH and ventromesial limbic prefrontal structures. In patients with left MTLE, functional connectivity maps (LMTLE – controls) showed for LA and LH decreased connectivity with DMN, contralateral hippocampus, and bilateral ventromesial limbic prefrontal regions; no change in connectivity was detected for RA; and for RH, there was decreased connectivity with DMN, bilateral ventromesial limbic prefrontal regions, and contralateral amygdala and hippocampus. Significance In unilateral MTLE, amygdala and hippocampus on the affected and to a lesser extent on the healthy side are less connected, and are also less connected with the dopaminergic mesolimbic and the DMNs. Changes in functional connectivity between mesial temporal lobe structures and these structures may explain cognitive and psychiatric impairments often found in patients with MTLE. PMID:22578020

  6. Avian Incubation Patterns Reflect Temporal Changes in Developing Clutches.

    PubMed

    Cooper, Caren B; Voss, Margaret A

    2013-01-01

    Incubation conditions for eggs influence offspring quality and reproductive success. One way in which parents regulate brooding conditions is by balancing the thermal requirements of embryos with time spent away from the nest for self-maintenance. Age related changes in embryo thermal tolerance would thus be expected to shape parental incubation behavior. We use data from unmanipulated Black-capped Chickadee (Poecile atricapillus) nests to examine the temporal dynamics of incubation, testing the prediction that increased heat flux from eggs as embryos age influences female incubation behavior and/or physiology to minimize temperature fluctuations. We found that the rate of heat loss from eggs increased with embryo age. Females responded to increased egg cooling rates by altering incubation rhythms (more frequent, shorter on- and off- bouts), but not brood patch temperature. Consequently, as embryos aged, females were able to increase mean egg temperature and decrease variation in temperature. Our findings highlight the need to view full incubation as more than a static rhythm; rather, it is a temporally dynamic and finely adjustable parental behavior. Furthermore, from a methodological perspective, intra- and inter-specific comparisons of incubation rhythms and average egg temperatures should control for the stage of incubation. PMID:23840339

  7. Avian Incubation Patterns Reflect Temporal Changes in Developing Clutches

    PubMed Central

    2013-01-01

    Incubation conditions for eggs influence offspring quality and reproductive success. One way in which parents regulate brooding conditions is by balancing the thermal requirements of embryos with time spent away from the nest for self-maintenance. Age related changes in embryo thermal tolerance would thus be expected to shape parental incubation behavior. We use data from unmanipulated Black-capped Chickadee (Poecile atricapillus) nests to examine the temporal dynamics of incubation, testing the prediction that increased heat flux from eggs as embryos age influences female incubation behavior and/or physiology to minimize temperature fluctuations. We found that the rate of heat loss from eggs increased with embryo age. Females responded to increased egg cooling rates by altering incubation rhythms (more frequent, shorter on- and off- bouts), but not brood patch temperature. Consequently, as embryos aged, females were able to increase mean egg temperature and decrease variation in temperature. Our findings highlight the need to view full incubation as more than a static rhythm; rather, it is a temporally dynamic and finely adjustable parental behavior. Furthermore, from a methodological perspective, intra- and inter-specific comparisons of incubation rhythms and average egg temperatures should control for the stage of incubation. PMID:23840339

  8. Experimental quiescent drifting dusty plasmas and temporal dust acoustic wave growth

    SciTech Connect

    Heinrich, J. R.; Kim, S.-H.; Meyer, J. K.; Merlino, R. L. [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States)

    2011-11-15

    We report on dust acoustic wave growth rate measurements taken in a dc (anode glow) discharge plasma device. By introducing a mesh with a variable bias 12-17 cm from the anode, we developed a technique to produce a drifting dusty plasma. A secondary dust cloud, free of dust acoustic waves, was trapped adjacent to the anode side of the mesh. When the mesh was returned to its floating potential, the secondary cloud was released and streamed towards the anode and primary dust cloud, spontaneously exciting dust acoustic waves. The amplitude growth of the excited dust acoustic waves was measured directly along with the wavelength and Doppler shifted frequency. These measurements were compared to fluid and kinetic dust acoustic wave theories. As the wave growth saturated a transition from linear to nonlinear waves was observed. The merging of the secondary and primary dust clouds was also observed.

  9. ORIGINAL PAPER Auditory temporal pattern learning by songbirds using maximal

    E-print Network

    Gentner, Timothy

    ) in the small sets of training and testing stimuli used. Here, we investi- gate this possibility, by asking animal) represents behaviorally relevant patterns in vocal J. A. Comins Á T. Q. Gentner (&) Department Jolla, CA, USA T. Q. Gentner Kavli Institute for Brain and Mind, La Jolla, CA, USA 123 Anim Cogn DOI 10

  10. Recognition and tracking of spatial–temporal congested traffic patterns on freeways

    Microsoft Academic Search

    Boris S. Kerner; Hubert Rehborn; Mario Aleksic; Andreas Haug

    2004-01-01

    The two models FOTO (Forecasting of Traffic Objects) and ASDA (Automatische Staudynamikanalyse: Automatic Tracking of Moving Traffic Jams) for the automatic recognition and tracking of congested spatial–temporal traffic flow patterns on freeways are presented. The models are based on a spatial–temporal traffic phase classification made in the three-phase traffic theory by Kerner. In this traffic theory, in congested traffic two

  11. Processes driving temporal dynamics in the nested pattern of waterbird communities

    NASA Astrophysics Data System (ADS)

    Sebastián-González, Esther; Botella, Francisco; Paracuellos, Mariano; Sánchez-Zapata, José Antonio

    2010-03-01

    Nestedness is a common pattern of bird communities in habitat patches, and it describes the situation where smaller communities form proper subsets of larger communities. Several studies have examined the processes causing nestedness and the implications for conservation, but few have considered the temporal changes in these processes. We used data from 6 years and two seasons (wintering and breeding) to explore the temporal changes in the causes of the nested pattern of a waterbird community in man-made irrigation ponds. Nestedness was significant in both seasons and in all years, and thus temporally stable. Despite the nestedness of waterbird communities, the proportion of idiosyncratic species (species that do not follow the nested pattern) was higher than in other studies. Furthermore, the idiosyncratic species often had endangered status. Selective colonisation and, mainly, selective extinction were the most important factors producing the nested pattern. In addition, the nested structure of the microhabitats at the ponds also caused the pattern. The causes of the pattern changed temporally even in the absence of big disturbance events. In general, breeding communities were more stable than wintering communities, and the seasonal differences in the causes of the nestedness were larger than the inter-annual differences. Consequently, studies of community nestedness from only one snapshot in time should be considered with caution.

  12. Learning temporal patterns of risk in a predator-diverse environment.

    PubMed

    Bosiger, Yoland J; Lonnstedt, Oona M; McCormick, Mark I; Ferrari, Maud C O

    2012-01-01

    Predation plays a major role in shaping prey behaviour. Temporal patterns of predation risk have been shown to drive daily activity and foraging patterns in prey. Yet the ability to respond to temporal patterns of predation risk in environments inhabited by highly diverse predator communities, such as rainforests and coral reefs, has received surprisingly little attention. In this study, we investigated whether juvenile marine fish, Pomacentrus moluccensis (lemon damselfish), have the ability to learn to adjust the intensity of their antipredator response to match the daily temporal patterns of predation risk they experience. Groups of lemon damselfish were exposed to one of two predictable temporal risk patterns for six days. "Morning risk" treatment prey were exposed to the odour of Cephalopholis cyanostigma (rockcod) paired with conspecific chemical alarm cues (simulating a rockcod present and feeding) during the morning, and rockcod odour only in the evening (simulating a rockcod present but not feeding). "Evening risk" treatment prey had the two stimuli presented to them in the opposite order. When tested individually for their response to rockcod odour alone, lemon damselfish from the morning risk treatment responded with a greater antipredator response intensity in the morning than in the evening. In contrast, those lemon damselfish previously exposed to the evening risk treatment subsequently responded with a greater antipredator response when tested in the evening. The results of this experiment demonstrate that P. moluccensis have the ability to learn temporal patterns of predation risk and can adjust their foraging patterns to match the threat posed by predators at a given time of day. Our results provide the first experimental demonstration of a mechanism by which prey in a complex, multi-predator environment can learn and respond to daily patterns of predation risk. PMID:22493699

  13. Learning Temporal Patterns of Risk in a Predator-Diverse Environment

    PubMed Central

    Bosiger, Yoland J.; Lonnstedt, Oona M.; McCormick, Mark I.; Ferrari, Maud C. O.

    2012-01-01

    Predation plays a major role in shaping prey behaviour. Temporal patterns of predation risk have been shown to drive daily activity and foraging patterns in prey. Yet the ability to respond to temporal patterns of predation risk in environments inhabited by highly diverse predator communities, such as rainforests and coral reefs, has received surprisingly little attention. In this study, we investigated whether juvenile marine fish, Pomacentrus moluccensis (lemon damselfish), have the ability to learn to adjust the intensity of their antipredator response to match the daily temporal patterns of predation risk they experience. Groups of lemon damselfish were exposed to one of two predictable temporal risk patterns for six days. “Morning risk” treatment prey were exposed to the odour of Cephalopholis cyanostigma (rockcod) paired with conspecific chemical alarm cues (simulating a rockcod present and feeding) during the morning, and rockcod odour only in the evening (simulating a rockcod present but not feeding). “Evening risk” treatment prey had the two stimuli presented to them in the opposite order. When tested individually for their response to rockcod odour alone, lemon damselfish from the morning risk treatment responded with a greater antipredator response intensity in the morning than in the evening. In contrast, those lemon damselfish previously exposed to the evening risk treatment subsequently responded with a greater antipredator response when tested in the evening. The results of this experiment demonstrate that P. moluccensis have the ability to learn temporal patterns of predation risk and can adjust their foraging patterns to match the threat posed by predators at a given time of day. Our results provide the first experimental demonstration of a mechanism by which prey in a complex, multi-predator environment can learn and respond to daily patterns of predation risk. PMID:22493699

  14. Analyzing spatio-temporal patterns of genuine cross-correlations.

    PubMed

    Rummel, Christian; Müller, Markus; Baier, Gerold; Amor, Frédérique; Schindler, Kaspar

    2010-08-15

    In multivariate time series analysis, the equal-time cross-correlation is a classic and computationally efficient measure for quantifying linear interrelations between data channels. When the cross-correlation coefficient is estimated using a finite amount of data points, its non-random part may be strongly contaminated by a sizable random contribution, such that no reliable conclusion can be drawn about genuine mutual interdependencies. The random correlations are determined by the signals' frequency content and the amount of data points used. Here, we introduce adjusted correlation matrices that can be employed to disentangle random from non-random contributions to each matrix element independently of the signal frequencies. Extending our previous work these matrices allow analyzing spatial patterns of genuine cross-correlation in multivariate data regardless of confounding influences. The performance is illustrated by example of model systems with known interdependence patterns. Finally, we apply the methods to electroencephalographic (EEG) data with epileptic seizure activity. PMID:20566351

  15. Spatial and temporal patterns of global onshore wind speed distribution

    NASA Astrophysics Data System (ADS)

    Zhou, Yuyu; Smith, Steven J.

    2013-09-01

    Wind power, a renewable energy source, can play an important role in electrical energy generation. Information regarding wind energy potential is important both for energy related modeling and for decision-making in the policy community. While wind speed datasets with high spatial and temporal resolution are often ultimately used for detailed planning, simpler assumptions are often used in analysis work. An accurate representation of the wind speed frequency distribution is needed in order to properly characterize wind energy potential. Using a power density method, this study estimated global variation in wind parameters as fitted to a Weibull density function using NCEP/climate forecast system reanalysis (CFSR) data over land areas. The Weibull distribution performs well in fitting the time series wind speed data at most locations according to R2, root mean square error, and power density error. The wind speed frequency distribution, as represented by the Weibull k parameter, exhibits a large amount of spatial variation, a regionally varying amount of seasonal variation, and relatively low decadal variation. We also analyzed the potential error in wind power estimation when a commonly assumed Rayleigh distribution (Weibull k = 2) is used. We find that the assumption of the same Weibull parameter across large regions can result in non-negligible errors. While large-scale wind speed data are often presented in the form of mean wind speeds, these results highlight the need to also provide information on the wind speed frequency distribution.

  16. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  17. Broadband negative acoustic radiation force by a soft thin plate patterned with periodical heavy grating

    E-print Network

    He, Hailong; He, Zhaojian; Denga, Ke; Zhao, Heping

    2015-01-01

    We investigate the acoustic radiation force (ARF) acting on a cylindrical brass particle near a soft thin plate patterned with periodical heavy grating. The existence of negative ARF is confirmed by which the particle near the surface of plate can be pulled backward. In addition, bandwidth for negative ARF in this soft plate system is found to be considerably broader compared with the stiff plate systems usually used in existing works. It is further demonstrated by field distribution analysis that this interesting negative ARF stems from the collective resonant excitation of the antisymmetric intrinsic Stoneley surface waves in the thin plate. Properties of ARF varying with the particle location and particle size are also investigated. The reported negative ARFs will have extensive application in manipulating particles by using of acoustic wave.

  18. Temporal and sequential patterns of agonistic behavior: effects of alcohol, anxiolytics and psychomotor stimulants.

    PubMed

    Miczek, K A; Haney, M; Tidey, J; Vatne, T; Weerts, E; DeBold, J F

    1989-01-01

    Social and agonistic interactions are composed of a range of species-typical acts, postures, displays and other communicative signals that follow characteristic patterns. Descriptive and analytic methods permit an assessment of the temporal and sequential features of highly probable patterns of agonistic interactions. Analysis of the intervals that separate consecutive attacks by a resident mouse or rat toward an intruder identifies bursts or epochs of attacks. Amphetamine (1.25, 2.5 mg/kg), but not diazepam or alcohol, alters the burst pattern of attack behavior. Higher doses of alcohol, but not diazepam, in either resident male rats or in lactating rats confronting an intruder, reduce the sequences of aggressive acts and postures with high transition probabilities as identified by lag sequential analysis. These results suggest that temporal and sequential patterning mechanisms may be differentially altered by amphetamine- and alcohol-type substances. These neural for many types of behavior. PMID:2567022

  19. Temporal patterns of tick-borne granulocytic anaplasmosis in California.

    PubMed

    Rejmanek, Daniel; Nieto, Nathan C; Barash, Nell; Foley, Janet E

    2011-06-01

    Granulocytic anaplasmosis (GA) is a tick-borne emerging infectious disease caused by the bacterium Anaplasma phagocytophilum. From fall 2005 to spring 2007, A. phagocytophilum infection prevalence in small mammals and tick abundance were monitored at 4 study sites in coastal California. The abundance of different life stages of questing Ixodes pacificus ticks fluctuated seasonally with the number of adults peaking December to February, nymphs peaking May to July, and larvae peaking April to June. Numerous Ixodes tick species were found attached to dusky-footed woodrats (Neotoma fuscipes), chimunks (Tamias spp.), and deer mice (Peromyscus maniculatus); however, attached tick larvae on all 3 rodent species were primarily I. pacificus, attached nymphs were primarily I. angustus, and adults were either I. ochotonae, I. spinipalpis, or I. woodi. A. phagocytophilum DNA was detected by PCR in 2.2% (n=275, 95% C.I.=0.09-4.9) of sampled ticks. The overall A. phagocytophilum seroprevalence among small mammals was 7.4% (n=654, 95% C.I.=5.5-9.7) while 7.2% (n=125, 95% C.I.=3.5-13.4) of the animals were found to be PCR-positive. Seropositive animals included woodrats, chipmunks, and deer mice, although only woodrats and chipmunks had PCR-detectable infections. Seroprevalence varied temporally among species with the majority of exposed deer mice detected in fall 2006 and the majority of exposed woodrats and chipmunks identified in spring 2007. This study highlights the importance of multiple-year monitoring of both vectors and wildlife hosts in order to better understand the complex ecology of A. phagocytophilum and other related tick-borne disease agents. PMID:21771541

  20. Visualizing temporal patterns of demand, throughput and crowding in an emergency department.

    PubMed

    Calvitti, Alan; Hoot, Nathan

    2007-01-01

    Emergency department (ED) operational data were calculated at 10-minute intervals throughout 2006 (n = 52561) in the adult ED of an academic medical center. Several operational parameters per observation were measured to better understand temporal patterns of input, throughput, and output of medical services. This may allow for improvement of predictive models of overcrowding. Visualization of this dataset is structured by a calendar template, facilitating discovery of cyclic patterns at diurnal, weekly, and monthly scales. PMID:18693989

  1. Comparison of temporal and spectral scattering methods using acoustically large breast models derived from magnetic resonance images.

    PubMed

    Hesford, Andrew J; Tillett, Jason C; Astheimer, Jeffrey P; Waag, Robert C

    2014-08-01

    Accurate and efficient modeling of ultrasound propagation through realistic tissue models is important to many aspects of clinical ultrasound imaging. Simplified problems with known solutions are often used to study and validate numerical methods. Greater confidence in a time-domain k-space method and a frequency-domain fast multipole method is established in this paper by analyzing results for realistic models of the human breast. Models of breast tissue were produced by segmenting magnetic resonance images of ex vivo specimens into seven distinct tissue types. After confirming with histologic analysis by pathologists that the model structures mimicked in vivo breast, the tissue types were mapped to variations in sound speed and acoustic absorption. Calculations of acoustic scattering by the resulting model were performed on massively parallel supercomputer clusters using parallel implementations of the k-space method and the fast multipole method. The efficient use of these resources was confirmed by parallel efficiency and scalability studies using large-scale, realistic tissue models. Comparisons between the temporal and spectral results were performed in representative planes by Fourier transforming the temporal results. An RMS field error less than 3% throughout the model volume confirms the accuracy of the methods for modeling ultrasound propagation through human breast. PMID:25096103

  2. Temporal trajectories of phosphorus and pedo-patterns mapped in Water Conservation Area 2, Everglades, Florida, USA

    E-print Network

    Grunwald, Sabine

    Temporal trajectories of phosphorus and pedo-patterns mapped in Water Conservation Area 2-patterns in Water Conservation Area 2, a subtropical wetland in the Everglades, Florida. Our specific objectives

  3. Spatio-Temporal Diffusion Pattern and Hotspot Detection of Dengue in Chachoengsao Province, Thailand

    PubMed Central

    Jeefoo, Phaisarn; Tripathi, Nitin Kumar; Souris, Marc

    2011-01-01

    In recent years, dengue has become a major international public health concern. In Thailand it is also an important concern as several dengue outbreaks were reported in last decade. This paper presents a GIS approach to analyze the spatial and temporal dynamics of dengue epidemics. The major objective of this study was to examine spatial diffusion patterns and hotspot identification for reported dengue cases. Geospatial diffusion pattern of the 2007 dengue outbreak was investigated. Map of daily cases was generated for the 153 days of the outbreak. Epidemiological data from Chachoengsao province, Thailand (reported dengue cases for the years 1999–2007) was used for this study. To analyze the dynamic space-time pattern of dengue outbreaks, all cases were positioned in space at a village level. After a general statistical analysis (by gender and age group), data was subsequently analyzed for temporal patterns and correlation with climatic data (especially rainfall), spatial patterns and cluster analysis, and spatio-temporal patterns of hotspots during epidemics. The results revealed spatial diffusion patterns during the years 1999–2007 representing spatially clustered patterns with significant differences by village. Villages on the urban fringe reported higher incidences. The space and time of the cases showed outbreak movement and spread patterns that could be related to entomologic and epidemiologic factors. The hotspots showed the spatial trend of dengue diffusion. This study presents useful information related to the dengue outbreak patterns in space and time and may help public health departments to plan strategies to control the spread of disease. The methodology is general for space-time analysis and can be applied for other infectious diseases as well. PMID:21318014

  4. Spatial and temporal patterns of carbon emissions from forest fires in China from 1950 to 2000

    E-print Network

    .1029/2005JD006198. 1. Introduction [2] Forest ecosystems play an important role in the global carbon cycle on the carbon cycle include both the direct release of carbon-containing trace gases into atmosphere throughSpatial and temporal patterns of carbon emissions from forest fires in China from 1950 to 2000

  5. Insights into temporal patterns of hospital patient safety from routinely collected electronic data

    PubMed Central

    2015-01-01

    Background The last two decades have seen an unprecedented growth in initiatives aimed to improve patient safety. For the most part, however, evidence of their impact remains controversial. At the same time, the healthcare industry has experienced an also unprecedented growth in the amount and variety of available electronic data. Methods In this paper, we provide a review of the use of routinely collected electronic data in the identification, analysis and surveillance of temporal patterns of patient safety. Results Two important temporal patterns of the safety of hospitalised patients were identified and discussed: long-term trends related to changes in clinical practice and healthcare policy; and shorter term patterns related to variations in workforce and resources. We found that consistency in reporting is intrinsically related to availability of large-scale, fit-for-purpose data. Consistent reported trends of patient harms included an increase in the incidence of post-operative sepsis and a decrease in central-line associated bloodstream infections. Improvement in the treatment of specific diseases, such as cardiac conditions, has also been demonstrated. Linkage of hospital data with other datasets provides essential temporal information about errors, as well as information about unsuspected system deficiencies. It has played an important role in the measurement and analysis of the effects of off-hours hospital operation. Conclusions Measuring temporal patterns of patient safety is still inadequate with electronic health records not yet playing an important role. Patient safety interventions should not be implemented without a strategy for continuous monitoring of their effect.

  6. Reconstruction of missing data in social networks based on temporal patterns of interactions

    NASA Astrophysics Data System (ADS)

    Stomakhin, Alexey; Short, Martin B.; Bertozzi, Andrea L.

    2011-11-01

    We discuss a mathematical framework based on a self-exciting point process aimed at analyzing temporal patterns in the series of interaction events between agents in a social network. We then develop a reconstruction model that allows one to predict the unknown participants in a portion of those events. Finally, we apply our results to the Los Angeles gang network.

  7. TEMPORALLY STABLE PATTERNS IN GRAIN YIELD AND SOIL WATER ON A DRYLAND CATENA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grain yields from dryland cropping systems can be affected by water availability, topographic position, and crop rotation. The temporal stability over multiple years of observed spatial patterns on a dryland catena is investigated. Questions remain about: 1) relationships between yield, soil water...

  8. Understanding the Spatial and Temporal Patterns of Wetland Evapotranspiration, Primary Production, and Nutrient Cycling

    E-print Network

    Goulden, Michael L.

    Understanding the Spatial and Temporal Patterns of Wetland Evapotranspiration, Primary Production the biogeochemical budgets and evapotranspiration in California wetlands are poorly understood. We propose research the CO2 exchange (FCO2) and evapotranspiration (E) between the atmosphere and the San Joaquin Marsh. Eddy

  9. Auditory Temporal Pattern Perception in 6- and 12-Month-Old Infants.

    ERIC Educational Resources Information Center

    Morrongiello, Barbara A.

    1984-01-01

    A go/no-go conditioned head-turn paradigm was used to examine the abilities of 6- and 12-month-olds to discriminate changes in temporal grouping and their perception of absolute and relative timing information when listening to patterns of white-noise bursts. (Author/RH)

  10. Temporal and spatial patterns of soil moisture in semiarid badlands of SE Spain

    Microsoft Academic Search

    Y. Canton; A. Sole-Benet; F. Domingo

    2004-01-01

    Temporal and spatial patterns of soil water content (?) have been studied in badlands in Tabernas (Almer??a, SE Spain). ? was measured on a detailed time scale for 18 months under different conditions of soil surface cover, soil properties and topography. ? was found to be highly spatially heterogeneous within small areas, controlled primarily by soil surface cover and soil

  11. A GIS-based Bayesian approach for analyzing spatial-temporal patterns of traffic crashes

    E-print Network

    Li, Linhua

    2009-06-02

    This thesis develops a GIS-based Bayesian approach for area-wide traffic crash analysis. Five years of crash data from Houston, Texas, are analyzed using a geographic information system (GIS), and spatial-temporal patterns of relative crash risk...

  12. TEMPORAL AND SPATIAL PATTERNS OF METHANE EMISSIONS FROM A RESERVOIR DRAINING AN AGRICULTURAL WATERSHED (abstract)

    EPA Science Inventory

    We used multiple approaches to characterize temporal and spatial patterns in methane (CH4) emissions from a mid-latitude reservoir (William H. Harsha Lake, Ohio, USA) draining an agricultural watershed. Weekly to monthly monitoring at six sites in the reservoir during a 13 month...

  13. TEMPORAL AND SPATIAL PATTERNS OF METHANE EMISSIONS FROM A RESERVOIR DRAINING AN AGRICULTURAL WATERSHED

    EPA Science Inventory

    We used multiple approaches to characterize temporal and spatial patterns in methane (CH4) emissions from a mid-latitude reservoir (William H. Harsha Lake, Ohio, USA) draining an agricultural watershed. Weekly to monthly monitoring at six sites in the reservoir during a 13 month...

  14. Temporal Patterns of Fruit Fly (Drosophila) Evolution Revealed by Mutation Clocks

    E-print Network

    Kumar, Sudhir

    Metropolitan University, Tokyo, Japan Drosophila melanogaster has been a canonical model organism to study times in the fruit fly phylogeny that led to the evolution of Drosophila melanogaster has been hinderedTemporal Patterns of Fruit Fly (Drosophila) Evolution Revealed by Mutation Clocks Koichiro Tamura

  15. Spatial and temporal pattern of Fgf8 expression during chicken development

    Microsoft Academic Search

    Daniel Stolte; Ruijin Huang; Bodo Christ

    2002-01-01

    This study analyzes the temporal and spatial expression pattern of Fgf-8 over a continuous series of developmental stages. Special emphasis is laid on the paraxial mesoderm where Fgf-8 expression is highly dynamic. Whereas the anterior portion of the unsegmented mesoderm is devoid of expression, Fgf-8 is upregulated in the posterior half of a newly formed somite. Soon after somite formation,

  16. Temporal Patterns of Nectar and Pollen Production in Aralia Hispida: Implications for Reproductive Success

    E-print Network

    Thomson, James D.

    Temporal Patterns of Nectar and Pollen Production in Aralia Hispida: Implications for Reproductive AND POLLEN PRODUCTION IN ARALIA HISPIDA: IMPLICATIONS FOR REPRODUCTIVE SUCCESS' JAMESD. THOMSONBrook,New York11794 USA Abstract. Large plants of Aralia hispida present their pollen and nectar in hundreds

  17. Temporal and spatial patterns in pelagic trawl fish catches in Lake Winnipeg

    Microsoft Academic Search

    Chelsey E. Lumb; William G. Franzin; Douglas A. Watkinson

    To better understand patterns of temporal and spatial variation of fish assemblages in offshore waters of Lake Winnipeg (Manitoba, Canada), midwater trawl tows were conducted near lakewide monitoring stations from 2002 to 2008. Trawl samples collected during spring, summer, and fall from the south basin, channel, and north basin were used to study effects of season and geographic region within

  18. Trapline foraging by bumble bees: III. Temporal patterns of visitation and foraging success at single plants

    Microsoft Academic Search

    Neal M. Williams; James D. Thomson

    1998-01-01

    We analyzed the temporal structure of visitation by bumble bee workers to a single Penstemon strictus plant growing in an array of conspccifics. When tested against a null distribution using a randomization model, the observed pattern of arrivals for the whole group of bees was random, but departures were clustered in time. Certain individuals visited the plant repeatedly and frequently

  19. Decentralised Evaluation of Temporal Patterns over Component-based Systems at Runtime

    E-print Network

    Paris-Sud XI, Université de

    , choosing a suitable adaptation policy in a current component-based system configuration depends- blocking environment with incomplete information about the component-based system that enables allDecentralised Evaluation of Temporal Patterns over Component-based Systems at Runtime Olga

  20. Encoding of Sound Localization Cues by an Identified Auditory Interneuron: Effects of Stimulus Temporal Pattern

    E-print Network

    Pollack, Gerald

    Encoding of Sound Localization Cues by an Identified Auditory Interneuron: Effects of Stimulus, Annie-He´le`ne and Gerald S. Pollack. Encoding of sound localization cues by an identified auditory interneuron: effects of stimulus temporal pattern. J Neurophysiol 88: 2322­2328, 2002; 10.1152/jn.00119

  1. Temporal and spatial expression patterns of canonical clock genes and clock-controlled genes in the

    E-print Network

    Silver, Rae

    Temporal and spatial expression patterns of canonical clock genes and clock-controlled genesB)-containing cells is retinorecipient and the cells therein lack rhythmic expression of clock genes and electrical of expression of the canonical clock genes Per1, Per2 and vasopressin mRNA, a clock-controlled gene

  2. A smart pattern recognition system for the automatic identification of aerospace acoustic sources

    NASA Technical Reports Server (NTRS)

    Cabell, R. H.; Fuller, C. R.

    1989-01-01

    An intelligent air-noise recognition system is described that uses pattern recognition techniques to distinguish noise signatures of five different types of acoustic sources, including jet planes, propeller planes, a helicopter, train, and wind turbine. Information for classification is calculated using the power spectral density and autocorrelation taken from the output of a single microphone. Using this system, as many as 90 percent of test recordings were correctly identified, indicating that the linear discriminant functions developed can be used for aerospace source identification.

  3. Spatial and temporal patterns of air pollutants in rural and urban areas of India.

    PubMed

    Sharma, Disha; Kulshrestha, U C

    2014-12-01

    In this study, we analysed spatial and temporal patterns of Suspended Particulate Matter (SPM) concentrations across India. We have also assessed MODIS-derived aerosol optical depth (AOD) variations to characterize the air quality and relate it to SPM, NO2 and SO2 in different areas. In addition, the pollutant concentrations have been mapped using geospatial techniques. The results indicated significant differences in air pollutant levels across rural and urban areas. In general, districts of central and northern India had relatively higher SPM concentrations compared to southern India. Out of the top ten SPM polluted districts in India, nine were located in the state of Uttar Pradesh (UP). We observed significant correlations between the SPM and AOD at different sites. Although spatial and temporal patterns of NO2 and SO2 matched AOD patterns, the correlation strength (r2) varied based on location. The causes and implications of these findings are presented. PMID:25244965

  4. Temporal Feeding Pattern May Influence Reproduction Efficiency, the Example of Breeding Mares

    PubMed Central

    Benhajali, Haifa; Ezzaouia, Mohammed; Lunel, Christophe; Charfi, Faouzia; Hausberger, Martine

    2013-01-01

    Discomfort in farm animals may be induced by inappropriate types or timing of food supplies. Thus, time restriction of meals and lack of roughage have been shown to be one source of emergence of oral stereotypies and abnormal behaviour in horses which have evolved to eat high-fibre diets in small amounts over long periods of time. This feeding pattern is often altered in domestic environment where horses are often fed low fibre meals that can be rapidly consumed. This study aimed at determining the effect of the temporal pattern of feeding on reproductive efficiency of breeding mares, One hundred Arab breeding mares were divided into two groups that differed only in the temporal pattern of roughage availability: only at night for the standard feeding pattern group (SFP mares), night and day for the “continuous feeding” group (CF mares). The total amount of roughage provided was the same as the CF mares received half of the hay during the day while in paddock (haynets). Mares were tested for oestrus detection by teasing with one stallion and were then examined clinically by rectal palpations and ultrasound before being mated naturally or inseminated by fresh or frozen semen. Multivariate logistic regression was used to analyse data. The treatment affected significantly the reproductive efficiency of the mares with fewer oestrus abnormalities (p?=?0.0002) and more fertility (p?=?0.024) in CF mares (conception rate?=?81% versus 55% in SFP mares). Ensuring semi-continous feeding by providing roughage may be a way of fulfilling the basic physiological needs of the horses' digestive system, reducing stress and associated inhibitors of reproduction. To our knowledge, this study provides the first evidence of an impact of temporal feeding patterns on reproductive success in a Mammal. Temporal patterns of feeding may be a major and underestimated factor in breeding. PMID:24098636

  5. Developmental regulation of spatio-temporal patterns of cortical circuit activation

    PubMed Central

    Griffen, Trevor C.; Wang, Lang; Fontanini, Alfredo; Maffei, Arianna

    2013-01-01

    Neural circuits are refined in an experience-dependent manner during early postnatal development. How development modulates the spatio-temporal propagation of activity through cortical circuits is poorly understood. Here we use voltage-sensitive dye imaging (VSD) to show that there are significant changes in the spatio-temporal patterns of intracortical signals in primary visual cortex (V1) from postnatal day 13 (P13), eye opening, to P28, the peak of the critical period for rodent visual cortical plasticity. Upon direct stimulation of layer 4 (L4), activity spreads to L2/3 and to L5 at all ages. However, while from eye opening to the peak of the critical period, the amplitude and persistence of the voltage signal decrease, peak activation is reached more quickly and the interlaminar gain increases with age. The lateral spread of activation within layers remains unchanged throughout the time window under analysis. These developmental changes in spatio-temporal patterns of intracortical circuit activation are mediated by differences in the contributions of excitatory and inhibitory synaptic components. Our results demonstrate that after eye opening the circuit in V1 is refined through a progression of changes that shape the spatio-temporal patterns of circuit activation. Signals become more efficiently propagated across layers through developmentally regulated changes in interlaminar gain. PMID:23316135

  6. Problems Associated with Statistical Pattern Recognition of Acoustic Emission Signals in a Compact Tension Fatigue Specimen

    NASA Technical Reports Server (NTRS)

    Hinton, Yolanda L.

    1999-01-01

    Acoustic emission (AE) data were acquired during fatigue testing of an aluminum 2024-T4 compact tension specimen using a commercially available AE system. AE signals from crack extension were identified and separated from noise spikes, signals that reflected from the specimen edges, and signals that saturated the instrumentation. A commercially available software package was used to train a statistical pattern recognition system to classify the signals. The software trained a network to recognize signals with a 91-percent accuracy when compared with the researcher's interpretation of the data. Reasons for the discrepancies are examined and it is postulated that additional preprocessing of the AE data to focus on the extensional wave mode and eliminate other effects before training the pattern recognition system will result in increased accuracy.

  7. On acoustic emission for failure investigation in CFRP: Pattern recognition and peak frequency analyses

    NASA Astrophysics Data System (ADS)

    Gutkin, R.; Green, C. J.; Vangrattanachai, S.; Pinho, S. T.; Robinson, P.; Curtis, P. T.

    2011-05-01

    This paper investigates failure in Carbon Fibre Reinforced Plastics CFRP using Acoustic Emission (AE). Signals have been collected and post-processed for various test configurations: tension, Compact Tension (CT), Compact Compression (CC), Double Cantilever Beam (DCB) and four-point bend End Notched Flexure (4-ENF). The signals are analysed with three different pattern recognition algorithms: k-means, Self Organising Map (SOM) combined with k-means and Competitive Neural Network (CNN). The SOM combined with k-means appears as the most effective of the three algorithms. The results from the clustering analysis follow patterns found in the peak frequencies distribution. A detailed study of the frequency content of each test is then performed and the classification of several failure modes is achieved.

  8. Temporal and Spatial Patterns of Habitat Use by Juveniles of a Small Coastal Shark (Mustelus lenticulatus) in an Estuarine Nursery

    PubMed Central

    Francis, Malcolm P.

    2013-01-01

    Juvenile rig (Mustelus lenticulatus) were internally tagged with acoustic transmitters and tracked with acoustic receivers deployed throughout two arms of Porirua Harbour, a small (7 km2) estuary in New Zealand. Ten rig were tracked for up to four months during summer–autumn to determine their spatial and temporal use of the habitat. The overall goal was to estimate the size of Marine Protected Areas required to protect rig nursery areas from direct human impacts. Rig showed clear site preferences, but those preferences varied among rig and over time. They spent most of their time in large basins and on shallow sand and mud flats around the margins, and avoided deep channels. Habitat range increased during autumn for many of the rig. Only one shark spent time in both harbour arms, indicating that there was little movement between the two. Rig home ranges were 2–7 km2, suggesting that an effective MPA would need to cover the entire Porirua Harbour. They moved to outer harbour sites following some high river flow rates, and most left the harbour permanently during or soon after a river spike, suggesting that they were avoiding low salinity water. Rig showed strong diel movements during summer, although the diel pattern weakened in autumn. Persistent use of the same day and night sites indicates that diel movements are directed rather than random. Further research is required to determine the sizes of rig home ranges in larger harbours where nursery habitat is more extensive. Marine Protected Areas do not control land-based impacts such as accelerated sedimentation and heavy metal pollution, so integration of marine and terrestrial management tools across a range of government agencies is essential to fully protect nursery areas. PMID:23437298

  9. 24-hour temporal pattern of NTPDase and 5'-nucleotidase enzymes in rat blood serum.

    PubMed

    Detanico, Bernardo Carraro; de Souza, Andressa; Medeiros, Liciane Fernandes; Rozisky, Joanna Ripoll; Caumo, Wolnei; Hidalgo, Maria Paz Loayza; Battastini, Ana Maria Oliveira; Torres, Iraci Lucena da Silva

    2010-10-01

    Circadian rhythms represent an important mechanism to prepare the organism for environmental variations. ATP, ADP, AMP, and adenosine can act as extracellular messengers in a range of biological processes and are metabolized by a number of enzymes, including NTPDases and 5'-nucleotidase. In the present study the authors report that ATPase and ADPase activities present 24-h temporal variations that peak during dark (activity) span. These findings suggest that this enzymatic temporal pattern in blood serum might be important for the normal physiology and function of the organism through the maintenance of extracellular nucleotides at physiological levels. PMID:20969521

  10. Discrimination of acoustic patterns in rats using the water T-maze

    PubMed Central

    de la Mora, Daniela M.; Toro, Juan M.

    2014-01-01

    The extraction of abstract rules and their generalization to new items has been proposed to be at the heart of higher cognitive functions such as language. Research with animals has shown that various species can extract rather complex patterns from the input, as well as establish abstract same/different relations. However, much of these findings have been observed after extensive training procedures. Here, we tested rats’ capacity to discriminate and generalize tone triplets that entailed a repetition from triplets that followed an ordinal, non-repeating pattern following a relatively short discrimination training procedure in a water T-maze. Our findings demonstrate that, under this procedure and after only 12 sessions, rats can learn to discriminate both patterns when a reliable difference in pitch variations is present across them (Experiment 1). When differences in pitch are eliminated (Experiment 2), no discrimination between patterns is found. Results suggest a procedure based on a water T-maze might be used to explore discrimination of acoustic patterns in rodents. PMID:25729120

  11. Spatial and temporal air quality pattern recognition using environmetric techniques: a case study in Malaysia.

    PubMed

    Syed Abdul Mutalib, Sharifah Norsukhairin; Juahir, Hafizan; Azid, Azman; Mohd Sharif, Sharifah; Latif, Mohd Talib; Aris, Ahmad Zaharin; Zain, Sharifuddin M; Dominick, Doreena

    2013-09-01

    The objective of this study is to identify spatial and temporal patterns in the air quality at three selected Malaysian air monitoring stations based on an eleven-year database (January 2000-December 2010). Four statistical methods, Discriminant Analysis (DA), Hierarchical Agglomerative Cluster Analysis (HACA), Principal Component Analysis (PCA) and Artificial Neural Networks (ANNs), were selected to analyze the datasets of five air quality parameters, namely: SO2, NO2, O3, CO and particulate matter with a diameter size of below 10 ?m (PM10). The three selected air monitoring stations share the characteristic of being located in highly urbanized areas and are surrounded by a number of industries. The DA results show that spatial characterizations allow successful discrimination between the three stations, while HACA shows the temporal pattern from the monthly and yearly factor analysis which correlates with severe haze episodes that have happened in this country at certain periods of time. The PCA results show that the major source of air pollution is mostly due to the combustion of fossil fuel in motor vehicles and industrial activities. The spatial pattern recognition (S-ANN) results show a better prediction performance in discriminating between the regions, with an excellent percentage of correct classification compared to DA. This study presents the necessity and usefulness of environmetric techniques for the interpretation of large datasets aiming to obtain better information about air quality patterns based on spatial and temporal characterizations at the selected air monitoring stations. PMID:23831918

  12. Intra-Population Genetic Variation in the Temporal Pattern of Egg Maturation in a Parasitoid Wasp

    PubMed Central

    Wajnberg, Eric; Curty, Christine; Jervis, Mark

    2012-01-01

    Parasitoid wasps are taxonomically and biologically extremely diverse. A conceptual framework has recently been developed for understanding life-history evolution and diversification in these animals, and it has confirmed that each of two linked life-history traits – the mode of larval development and the temporal pattern of egg maturation – acts as an organiser of life-history. The framework has been predicated on the assumption that there exists sufficient genetic variation in the latter trait to allow it to be shaped by natural selection. Focusing on the parasitoid wasp Trichogramma brassicae, our aim was to test the validity of that assumption, using established quantitative genetic methods. We demonstrate the existence of a statistically significant degree of intra-population polygenic variation in the temporal pattern of egg production within the wasp population we studied. Furthermore, our results, together with published data on clinal variation in the egg maturation pattern of another species, suggest that intra-specific evolutionary shifts in the temporal pattern of egg maturation of parasitoid wasps can result from a change in allocation to egg production either before, or very shortly after adult emergence, without there being an accompanying change in lifetime fecundity. As well as opening new avenues of research into the reproductive strategies, behaviour, community organisation and biological control potential of parasitoid wasps, this discovery also has implications for studies of life-history evolution and diversification in insects generally. PMID:23029312

  13. Three Eurasian teleconnection patterns: spatial structures, temporal variability, and associated winter climate anomalies

    NASA Astrophysics Data System (ADS)

    Liu, Yuyun; Wang, Lin; Zhou, Wen; Chen, Wen

    2014-06-01

    The Eurasian (EU) pattern is a distinct teleconnection pattern observed in boreal winter. Since the EU pattern was first identified, three types have been reported in the literature: the conventional EU pattern; the type 1 EU pattern, or Scandinavian (SCAND) pattern; and the type 2 EU pattern, or East Atlantic/West Russia (EATL/WRUS) pattern. Based on several reanalysis and observational datasets, the three EU patterns are extracted using the rotated empirical orthogonal function method. In order to provide a further distinction and understanding of the three EU patterns, a comprehensive side-by-side comparison is performed among them including their temporal variability, horizontal and vertical structure, related stationary Rossby wave activity, impact on climate, and possible driving factors associated with external forcing. The results reveal that all three EU patterns are characterised by a clear quasi-barotropic wave-train structure, but each has a distinct source and centre of action. Accordingly, their impacts on the precipitation and surface air temperature also differ from one other. Further evidence suggests that the conventional EU pattern is likely driven by anomalous sea surface temperatures (SST) over the North Atlantic, in which process the transient eddies are actively involved. The SCAND pattern is partly maintained by the vorticity source over Western Europe, which arises from the anomalous convergence/divergence over the Mediterranean and is efficiently driven by the tropical and southern Indian Ocean SST via divergent circulation. The EATL/WRUS pattern shows some linkage to the North American snow cover, and the involved process remains unclear and needs further investigation.

  14. Dynamic temporal patterns of nearshore seepage flux in a headwater Adirondack lake

    NASA Astrophysics Data System (ADS)

    Sebestyen, Stephen D.; Schneider, Rebecca L.

    2001-07-01

    Although seepage in lakes is known to vary as a function of precipitation and watershed characteristics, temporal patterns of seepage flux over daily and weekly time scales have not been extensively studied with a concentrated effort of direct measurement of seepage in nearshore areas. In this study, seepage was intensively measured with seepage meters over two summers and during snowmelt in Lower Sylvan Pond, a small lake in the Adirondack Mountains region of New York State, USA. A consistent pattern of slight discharge (never exceeding 105 mL m -2 h -1) was observed at three stations along a segment of the shoreline near the inlet stream. A distinct temporal pattern of seepage was observed at three stations along another portion of the shoreline. Seepage discharged (>400 mL m -2 h -1) for a portion of the summer in 1998 and then shifted to recharge (<-500 mL m -2 h -1) for the remainder of the summer. A similar temporal pattern was observed again in 1999 but the transition to recharge occurred earlier and higher rates of discharge (610 mL m -2 h -1) and recharge (-608 mL m -2 h -1) were recorded. Additionally, seepage at these three stations increased after large rainfall events and a pronounced episodic increase of seepage was measured during snowmelt. Distinct seepage patterns along portions of the shoreline show that seepage can vary considerably within seasons and suggests a need to consider changes of seepage over time periods of days to weeks as well as among seasons and years. This study demonstrates that the resolution of temporal seepage data can be important to the understanding of water fluxes to aquatic ecosystems.

  15. Exploratory Analysis of Spatial-Temporal Patterns of Air Pollution in the City

    NASA Astrophysics Data System (ADS)

    Champendal, Alexandre; Kanevski, Mikhail; Huguenot, Pierre-Emmanuel; Golay, Jean

    2013-04-01

    Air pollution in the city is an important problem influencing environment, well-being of society, economy, management of urban zones, etc. The problem is extremely difficult due to a very complex distribution of the pollution sources, morphology of the city and dispersion processes leading to multivariate nature of the phenomena and high local spatial-temporal variability. The task of understanding, modelling and prediction of spatial-temporal patterns of air pollution in urban zones is an interesting and challenging topic having many research axes from science-based modelling to geostatistics and data mining. The present research mainly deals with a comprehensive exploratory analysis of spatial-temporal air pollution data using statistical, geostatistical and machine learning tools. This analysis helps to 1) understand and model spatial-temporal correlations using variography, 2) explore the temporal evolution of spatial correlation matrix; 3) analyse and visualize an interconnection between measurement stations using network science tools; 4) quantify the availability and predictability of structured patterns. The real data case study deals with spatial-temporal air pollution data of canton Geneva (2002-2011). Carbon dioxide (NO2) have caught our attention. It has effects on health: nitrogen dioxide can irritate the lungs, effects on plants; NO2 contributes to the phenomenon of acid rain. The negative effects of nitrogen dioxides on plants are reducing the growth, production and pesticide resistance. And finally the effects on materials: nitrogen dioxides increase the corrosion. Well-defined patterns of spatial-temporal correlations were detected. The analysis and visualization of spatial correlation matrix for 91 stations were carried out using the network science tools and high levels of clustering were revealed. Moving Window Correlation Matrix and Spatio-temporal variography methods were applied to define and explore the dynamic of our data. More than just exploratory of data analysis, this study brings to front the high complexity of air pollution in the city. This approach allowed the definition, parameterisation and analysis of the air pollution data in the city with the future goal of integrating this knowledge in the development of different models of air pollution diffusion. Keywords: space-time environmental data, variography, moving window correlation matrix, network science

  16. Assessment of Temporal State-Dependent Interactions between Auditory fMRI Responses to Desired and Undesired Acoustic Sources

    PubMed Central

    Olulade, O.; Hu, S.; Gonzalez-Castillo, J.; Tamer, G.G; Luh, W-M; Ulmer, J.L.; Talavage, T.M.

    2011-01-01

    A confounding factor in auditory functional magnetic resonance imaging (fMRI) experiments is the presence of the acoustic noise inherently associated with the echo planar imaging acquisition technique. Previous studies have demonstrated that this noise can induce unwanted neuronal responses that can mask stimulus-induced responses. Similarly, activation accumulated over multiple stimuli has been demonstrated to elevate the baseline, thus reducing the dynamic range available for subsequent responses. To best evaluate responses to auditory stimuli, it is necessary to account for the presence of all recent acoustic stimulation, beginning with an understanding of the attenuating effects brought about by interaction between and among induced unwanted neuronal responses, and responses to desired auditory stimuli. This study focuses on the characterization of the duration of this temporal memory and qualitative assessment of the associated response attenuation. Two experimental parameters — inter-stimulus interval (ISI) and repetition time (TR) — were varied during an fMRI experiment in which participants were asked to passively attend to an auditory stimulus. Results present evidence of a state-dependent interaction between induced responses. As expected, attenuating effects of these interactions become less significant as TR and ISI increase and in contrast to previous work, persist up to 18s after a stimulus presentation. PMID:21426929

  17. Emergence of striation patterns in acoustic signals reflected from dynamic surface waves.

    PubMed

    Choo, Youngmin; Seong, Woojae; Song, Heechun

    2014-09-01

    A striation pattern can emerge in high-frequency acoustic signals interacting with dynamic surface waves. The striation pattern is analyzed using a ray tracing algorithm for both a sinusoidal and a rough surface. With a source or receiver close to the surface, it is found that part of the surface on either side of the specular reflection point can be illuminated by rays, resulting in time-varying later arrivals in channel impulse response that form the striation pattern. In contrast to wave focusing associated with surface wave crests, the striation occurs due to reflection off convex sections around troughs. Simulations with a sinusoidal surface show both an upward (advancing) and downward (retreating) striation patterns that depend on the surface-wave traveling direction and the location of the illuminated area. In addition, the striation length is determined mainly by the depth of the source or receiver, whichever is closer in range to the illuminated region. Even with a rough surface, the striation emerges in both directions. However, broadband (7-13?kHz) simulations in shallow water indicate that the longer striation in one direction is likely pronounced against a quiet noise background, as observed from at-sea experimental data. PMID:25190380

  18. Automatic classification of acetowhite temporal patterns to identify precursor lesions of cervical cancer

    NASA Astrophysics Data System (ADS)

    Gutiérrez-Fragoso, K.; Acosta-Mesa, H. G.; Cruz-Ramírez, N.; Hernández-Jiménez, R.

    2013-12-01

    Cervical cancer has remained, until now, as a serious public health problem in developing countries. The most common method of screening is the Pap test or cytology. When abnormalities are reported in the result, the patient is referred to a dysplasia clinic for colposcopy. During this test, a solution of acetic acid is applied, which produces a color change in the tissue and is known as acetowhitening phenomenon. This reaction aims to obtaining a sample of tissue and its histological analysis let to establish a final diagnosis. During the colposcopy test, digital images can be acquired to analyze the behavior of the acetowhitening reaction from a temporal approach. In this way, we try to identify precursor lesions of cervical cancer through a process of automatic classification of acetowhite temporal patterns. In this paper, we present the performance analysis of three classification methods: kNN, Naïve Bayes and C4.5. The results showed that there is similarity between some acetowhite temporal patterns of normal and abnormal tissues. Therefore we conclude that it is not sufficient to only consider the temporal dynamic of the acetowhitening reaction to establish a diagnosis by an automatic method. Information from cytologic, colposcopic and histopathologic disciplines should be integrated as well.

  19. Diatoms reveal complex spatial and temporal patterns of recent limnological change in West Greenland

    Microsoft Academic Search

    Bianca B. Perren; Marianne S. V. Douglas; N. John Anderson

    2009-01-01

    Diatoms in sediment cores were analysed across a range of stratigraphic resolutions along a transect of 23 lakes spanning\\u000a the ice-free margin of the west coast of Greenland (~67°N), to explore spatial and temporal patterns of recent (last ~150 years)\\u000a environmental change in the region. These records display heterogeneous lake development trajectories over the last several\\u000a centuries. Estimates of species composition

  20. The predatory behavior of wintering Accipiter hawks: temporal patterns in activity of predators and prey

    Microsoft Academic Search

    Timothy C. Roth; Steven L. Lima

    2007-01-01

    Studies focused on how prey trade-off predation and starvation risk are prevalent in behavioral ecology. However, our current\\u000a understanding of these trade-offs is limited in one key respect: we know little about the behavior of predators. In this study,\\u000a we provide some of the first detailed information on temporal patterns in the daily hunting behavior of bird-eating Accipiter hawks and

  1. Spatial and Temporal Patterns in Macrofaunal Diversity Components Relative to Sea Floor Landscape Structure

    PubMed Central

    Zajac, Roman N.; Vozarik, Joseph M.; Gibbons, Brittney R.

    2013-01-01

    We examined temporal changes in macrofaunal ?- and ?-diversity over several spatial scales (within patches, among patches, across landscapes and across regions) in Long Island Sound on the northeast USA coast. Regional ?-diversity was estimated at 144 taxa, however ?-diversity fluctuated over time as did ?- and ?-diversity components. Based on additive partitioning, patch- and region-scale ?-diversity components generally had the highest contributions to ?-diversity; lower percentages were found at within-patch and landscape scales. Multiplicative diversity partitioning indicated highest species turnover at within- and among patch scales. For all partition results, within-patch and patch-scale ?-diversity increased sharply when hypoxia impacted benthic communities. Spatial variation in diversity components can be attributed to the collection of different patch types at varying spatial scales and their associated habitats across the benthic landscapes, as well as gradients in depth and other estuarine-scale characteristics. Temporal variation in diversity components across spatial scales may be related to seasonal changes in habitat heterogeneity, species population dynamics, and seasonal disturbances. Rare species were significant and temporally consistent components of macrofaunal diversity patterns over different spatial scales. Our findings agree with other marine and terrestrial studies that show diversity components vary significantly over different spatial scales and the importance of habitat/landscape heterogeneity in supporting diversity. However, our results indicate that the relative contributions of scale-specific ?-diversity components can also change significantly over time. Thus, studies of diversity patterns across patches and landscapes based on data collected at one time, or assembled into a single data set from different times, may not capture the full suite of diversity patterns that occur over varying spatial scales and any time-specific determinants of those patterns. Many factors that shape and maintain sedimentary communities vary temporally, and appear to play an important role in determining and maintaining macrofaunal diversity over different spatial scales. PMID:23776552

  2. Spatial and temporal pattern in seagrass community composition and productivity in south Florida

    Microsoft Academic Search

    J. W. Fourqurean; A. Willsie; C. D. Rose; L. M. Rutten

    2001-01-01

    We document the distribution and abundance of seagrasses, as well as the intra-annual temporal patterns in the abundance\\u000a of seagrasses and the productivity of the nearshore dominant seagrass (Thalassia testudinum) in the south Florida region. At least one species of seagrass was present at 80.8% of 874 randomly chosen mapping sites,\\u000a delimiting 12,800?km2 of seagrass beds in the 17,000-km2 survey

  3. Microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks

    Microsoft Academic Search

    Boris S. Kerner; Sergey L. Klenov

    2003-01-01

    A microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks due to on-ramps, merge bottlenecks (a reduction of highway lanes), and off-ramps is presented. The basic postulate of three-phase traffic theory is used, which claims that homogeneous (in space and time) model solutions (steady states) of synchronized flow cover a two dimensional region in the flow-density plane [B. S.

  4. On the spatio-temporal patterns formation in low-temperature plasmas

    Microsoft Academic Search

    D. G. Dimitriu

    2008-01-01

    Experimental results concerning the formation of spatial and spatio-temporal patterns in low-temperature discharge plasmas are presented. These structures appear as single or multiple luminous structures attached to the anode surface, or electrode-free in the case of radio-frequency or microwave plasmas. Probe measurements revealed that a double layer exists at the edge of each structure, controlling the particle and energy exchange

  5. Study of Spatio-Temporal Immunofluorescence on Bead Patterns in a Microfluidic Channel

    NASA Astrophysics Data System (ADS)

    Sivagnanam, Venkataragavalu; Yang, Hui; Gijs, Martin A. M.

    2010-12-01

    We performed a direct immunoassay inside a microfluidic channel on patterned streptavidin-coated beads, which captured fluorescently-labeled biotin target molecules from a continuous flow. We arranged the beads in a dot array at the bottom of the channel and demonstrated their position- and flow rate-dependent fluorescence. As the target analyte gets gradually depleted from the flow when passing downstream the channel, the highest fluorescence intensity was observed on the most upstream positioned dot patterns. We propose a simple analytical convection model to explain this spatio-temporal fluorescence.

  6. Transient dynamics and rhythm coordination of inferior olive spatio-temporal patterns

    PubMed Central

    Latorre, Roberto; Aguirre, Carlos; Rabinovich, Mikhail I.; Varona, Pablo

    2013-01-01

    The inferior olive (IO) is a neural network belonging to the olivo-cerebellar system whose neurons are coupled with electrical synapses and display subthreshold oscillations and spiking activity. The IO is frequently proposed as the generator of timing signals to the cerebellum. Electrophysiological and imaging recordings show that the IO network generates complex spatio-temporal patterns. The generation and modulation of coherent spiking activity in the IO is one key issue in cerebellar research. In this work, we build a large scale IO network model of electrically coupled conductance-based neurons to study the emerging spatio-temporal patterns of its transient neuronal activity. Our modeling reproduces and helps to understand important phenomena observed in IO in vitro and in vivo experiments, and draws new predictions regarding the computational properties of this network and the associated cerebellar circuits. The main factors studied governing the collective dynamics of the IO network were: the degree of electrical coupling, the extent of the electrotonic connections, the presence of stimuli or regions with different excitability levels and the modulatory effect of an inhibitory loop (IL). The spatio-temporal patterns were analyzed using a discrete wavelet transform to provide a quantitative characterization. Our results show that the electrotonic coupling produces quasi-synchronized subthreshold oscillations over a wide dynamical range. The synchronized oscillatory activity plays the role of a timer for a coordinated representation of spiking rhythms with different frequencies. The encoding and coexistence of several coordinated rhythms is related to the different clusterization and coherence of transient spatio-temporal patterns in the network, where the spiking activity is commensurate with the quasi-synchronized subthreshold oscillations. In the presence of stimuli, different rhythms are encoded in the spiking activity of the IO neurons that nevertheless remains constrained to a commensurate value of the subthreshold frequency. The stimuli induced spatio-temporal patterns can reverberate for long periods, which contributes to the computational properties of the IO. We also show that the presence of regions with different excitability levels creates sinks and sources of coordinated activity which shape the propagation of spike wave fronts. These results can be generalized beyond IO studies, as the control of wave pattern propagation is a highly relevant problem in the context of normal and pathological states in neural systems (e.g., related to tremor, migraine, epilepsy) where the study of the modulation of activity sinks and sources can have a potential large impact. PMID:24046731

  7. Implications of high resolution spatial and temporal rainfall patterns for shallow landslide triggering at catchment scale

    NASA Astrophysics Data System (ADS)

    von Ruette, Jonas; Lehmann, Peter; Or, Dani

    2013-04-01

    Triggering of shallow landslides is often associated with heavy rainfall events where infiltrating water decreases soil strength and increases mechanical load and pore pressure in the soil mantle. The nature of hydrological loading of slopes necessitates information on spatial and temporal distribution of rainfall intensities that are often deduced from hourly radar-data with spatial resolution of a few kilometers that smooth out much of the critical rainfall pattern heterogeneity essential to the triggering process. We explore the role of rainfall heterogeneity on volume and time of mass release using a 'catchment-scale landslide hydrological-triggering model' (CLHT). The study area for this analysis is a small catchment where a local summer storm in 2002 triggered 51 shallow landslides. Artificial heterogeneous rainfall maps were created based on the constraint that the total rainfall added to the catchment corresponds to the amount measured with radar data during actual triggering event. Simulated landslide maps reveal that rainfall pattern scenarios play a major role for the spatial and temporal failure dynamics and affects number, volume, and location of landslides. The interplay of soil hydraulic conductivity and infiltration capacity and runoff generation may reduce soil weakening and decrease landslide susceptibility. Results suggest that highly resolved rainfall spatio-temporal pattern may hold the key to understanding mechanisms of landslide hydro-mechanical triggering that are presently obscured by the use of areal mean rainfall and thus may help advance predictability of such common natural hazard.

  8. Searching for the holy grail: temporally informative firing patterns in the rat.

    PubMed

    Matell, Matthew S

    2014-01-01

    This chapter reviews our work from the past decade investigating cortical and striatal firing patterns in rats while they time intervals in the multi-seconds range. We have found that both cortical and striatal firing rates contain information that the rat can use to identify how much time has elapsed both from trial onset and from the onset of an active response state. I describe findings showing that the striatal neurons that are modulated by time are also modulated by overt behaviors, suggesting that time modulates the strength of motor coding in the striatum, rather than being represented as an abstract quantity in isolation. I also describe work showing that there are a variety of temporally informative activity patterns in pre-motor cortex, and argue that the heterogeneity of these patterns can enhance an organism's temporal estimate. Finally, I describe recent behavioral work from my lab in which the simultaneous cueing of multiple durations leads to a scalar temporal expectation at an intermediate time, providing strong support for a monotonic representation of time. PMID:25358713

  9. General and rare bacterial taxa demonstrating different temporal dynamic patterns in an activated sludge bioreactor.

    PubMed

    Kim, Taek-Seung; Jeong, Ju-Yong; Wells, George F; Park, Hee-Deung

    2013-02-01

    Temporal variation of general and rare bacterial taxa was investigated using pyrosequencing of 16S rRNA gene from activated sludge samples collected bimonthly for a two-year period. Most of operational taxonomic units (OTUs) were allocated to rare taxa (89.6%), but the rare taxa comprised a small portion of the community in terms of abundance of sequences analyzed (28.6%). Temporal variations in OTUs richness significantly differed between the two taxa groups in which the rare taxa showed a higher diversity and a more fluctuating pattern than the general taxa. Furthermore, the two taxa groups were constrained by different explanatory variables: influent BOD, effluent BOD, and DO were the significant (P?pattern of the general taxa, while temperature was the factor for the rare taxa. Over the test period, the general taxa persisted for a longer time (i.e., lower turnover rate) in the bioreactor than the rare taxa. In conclusion, this study demonstrated clear differences in temporal dynamic patterns for the general and rare bacterial taxa in an activated sludge bioreactor, which would be a foundation for better understanding the bacterial ecology of activated sludge. PMID:22526777

  10. Spatio-temporal soil moisture patterns - A meta-analysis using plot to catchment scale data

    NASA Astrophysics Data System (ADS)

    Korres, W.; Reichenau, T. G.; Fiener, P.; Koyama, C. N.; Bogena, H. R.; Cornelissen, T.; Baatz, R.; Herbst, M.; Diekkrüger, B.; Vereecken, H.; Schneider, K.

    2015-01-01

    Soil moisture is a key variable in hydrology, meteorology and agriculture. It is influenced by many factors, such as topography, soil properties, vegetation type, management, and meteorological conditions. The role of these factors in controlling the spatial patterns and temporal dynamics is often not well known. The aim of the current study is to analyze spatio-temporal soil moisture patterns acquired across a variety of land use types, on different spatial scales (plot to meso-scale catchment) and with different methods (point measurements, remote sensing, and modeling). We apply a uniform set of tools to determine method specific effects, as well as site and scale specific controlling factors. Spatial patterns of soil moisture and their temporal development were analyzed using nine different datasets from the Rur catchment in Western Germany. For all datasets we found negative linear relationships between the coefficient of variation and the mean soil moisture, indicating lower spatial variability at higher mean soil moisture. For a forest sub-catchment compared to cropped areas, the offset of this relationship was larger, with generally larger variability at similar mean soil moisture values. Using a geostatistical analysis of the soil moisture patterns we identified three groups of datasets with similar values for sill and range of the theoretical variogram: (i) modeled and measured datasets from the forest sub-catchment (patterns mainly influenced by soil properties and topography), (ii) remotely sensed datasets from the cropped part of the Rur catchment (patterns mainly influenced by the land-use structure of the cropped area), and (iii) modeled datasets from the cropped part of the Rur catchment (patterns mainly influenced by large scale variability of soil properties). A fractal analysis revealed that all analyzed soil moisture patterns showed a multifractal behavior, with at least one scale break and generally high fractal dimensions. Corresponding scale breaks were found between different datasets. The factors causing these scale breaks are consistent with the findings of the geostatistical analysis. Furthermore, the joined analysis of the different datasets showed that small differences in soil moisture dynamics, especially at the upper and lower bounds of soil moisture (at maximum porosity and wilting point of the soils) can have a large influence on the soil moisture patterns and their autocorrelation structure. Depending on the prevalent type of land use and the time of year, vegetation causes a decrease or an increase of spatial variability in the soil moisture pattern.

  11. Using Temporal Patterns (T-Patterns) to Derive Stress Factors of Routine

    E-print Network

    Su, Norman Makoto

    , T-patterns, routine tasks, stress factors ACM Classification Keywords H.1.2 User/Machine Systems schedule. Reddy and Dourish [2] conducted ethnography at a hospital to examine how people use work rhythms to accomplish information seeking. For example, rhythms can provide valuable information between nurses

  12. Spatio-Temporal Expression Pattern of Frizzled Receptors after Contusive Spinal Cord Injury in Adult Rats

    PubMed Central

    Arenas, Ernest; Rodriguez, Francisco Javier

    2012-01-01

    Background Wnt proteins are a large family of molecules that are critically involved in multiple central nervous system (CNS) developmental processes. Experimental evidences suggest a role for this family of proteins in many CNS disorders, including spinal cord injury (SCI), which is a major neuropathology owing to its high prevalence and chronic sensorimotor functional sequelae. Interestingly, most Wnt proteins and their inhibitors are expressed in the uninjured spinal cord, and their temporal expression patterns are dramatically altered after injury. However, little is known regarding the expression of their better-known receptors, the Frizzled family, after SCI. Thus, the aim of the present study was to evaluate the expression of Frizzled receptors in the damaged spinal cord. Findings Based on the evidence that Wnts are expressed in the spinal cord and are transcriptionally regulated by SCI in adulthood, we analysed the spatio-temporal mRNA and protein expression patterns of Frizzled receptors after contusive SCI using quantitative RT-PCR and single and double immunohistochemistry, respectively. Our results show that almost all of the 10 known Frizzled receptors were expressed in specific spatial patterns in the uninjured spinal cords. Moreover, the Frizzled mRNAs and proteins were expressed after SCI, although their expression patterns were altered during the temporal progression of SCI. Finally, analysis of cellular Frizzled 5 expression pattern by double immunohistochemistry showed that, in the uninjured spinal cord, this receptor was expressed in neurons, oligodendrocytes, astrocytes, microglia and NG2+ glial precursors. After injury, Frizzled 5 was not only still expressed in oligodendrocytes, astrocytes and NG2+ glial precursors but also in axons at all evaluated time points. Moreover, Frizzled 5 was expressed in reactive microglia/macrophages from 3 to 14 days post-injury. Conclusions Our data suggest the involvement of Frizzled receptors in physiological spinal cord function and in the cellular and molecular events that characterise its neuropathology. PMID:23251385

  13. Spatio-temporal patterns of forest fires: a comprehensive application of the K-function

    NASA Astrophysics Data System (ADS)

    Tonini, Marj; Vega Orozco, Carmen; Kanevski, Mikhaïl; Conedera, Marco

    2013-04-01

    The spatial distribution of uncontrolled hazardous events, such as forest fires, is largely investigated from the scientific community with the purpose of finding out the more vulnerable areas. Mapping the location of spatio-temporal sequences for a given environmental dataset is of great impact; however, the majority of the studies miss the analysis of the aggregation over time. Nonetheless discovering unusual temporal pattern for a given time sequence is fundamental to understand the phenomena and underlying processes. The present study aims investigating both the spatial and the temporal cluster behaviour of forest fires occurrences registered in Canton Ticino (Switzerland) over a period of about 40 years and testing if space and time interact in generate clusters. To do this, the purely spatial, the time and the space-time extensions of the Ripley's K-function were applied. The Ripley's K-function is a statistic exploratory method which enables detecting whether or not a point process (e.g. the location of the ignition points) is randomly distributed. The purely spatial K-function K(r) is defined as the expected number of further events within an area of radius r around an arbitrary point of the pattern, divided by the intensity of the phenomenon. Under completely spatial randomness, the value of the K(r) is equal to the area around the point (=?r2), while observations above this theoretical value imply a clustering behaviour at the corresponding distance r. For the purely time analysis, the Ripley's K-function K(t) can be taught as a reformulation of the spatial version to detect unexpected aggregation of events over the temporal scale. For its computation, the value of the intensity used in K(r) is replaced by the total duration of the time sequence divided by the total number of observed events, and the distance r is replaced by the time interval t. Under time-regularity, K(t) equals 2t, whereas, observed measures above this theoretical value indicate a temporal cluster behaviour at the corresponding temporal scale t. For the analysis of the space-time clustering, we applied the spatio-temporal (bivariate) K-function K(r,t), which evaluates if events are closer in both space and time. Intuitively, if there is no space-time interaction K(r,t) = K(r) * K(t). Accordingly, if K(r,t) minus K(r) * K(t) is positive, this indicates an interaction between space and time in producing clusters, which arise from a well detectable spatial and temporal scales. This study allowed detecting: 1) the purely spatial and the purely temporal scales at which the registered forest fires events are clustered, given by the results of the K(r) and the K(t) computations; and 2) the time period where spatial clusters take place at a given distance scale, exhibited by the results of the K(r,t) computation. Key words: spatio-temporal sequences, cluster, Ripley's K-function, forest fires. Acknowledgements This work was partly supported by the SNFS Project No. 200021-140658, "Analysis and Modelling of Space-Time Patterns in Complex Regions". References - Bivand R., Rowlingson B., and Diggle P. (2012) - splancs package in R project - Diggle P., Chetwynd A., Haggkvist R. and Morris S. (1995) Second-order analysis of space-time clustering. Statistical Methods in Medical Research, vol. 4(2): 124-136. - R Development Core Team (2012). R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. URL: http://www.R-project.org/. - Vega Orozco C., Tonini M., Conedera M., Kanveski M. (2012) Cluster recognition in spatial-temporal sequences: the case of forest fires, GeoInformatica, vol. 16(4): 653-673.

  14. Acoustic Emission Patterns and the Transition to Ductility in Sub-Micron Scale Laboratory Earthquakes

    NASA Astrophysics Data System (ADS)

    Ghaffari, H.; Xia, K.; Young, R.

    2013-12-01

    We report observation of a transition from the brittle to ductile regime in precursor events from different rock materials (Granite, Sandstone, Basalt, and Gypsum) and Polymers (PMMA, PTFE and CR-39). Acoustic emission patterns associated with sub-micron scale laboratory earthquakes are mapped into network parameter spaces (functional damage networks). The sub-classes hold nearly constant timescales, indicating dependency of the sub-phases on the mechanism governing the previous evolutionary phase, i.e., deformation and failure of asperities. Based on our findings, we propose that the signature of the non-linear elastic zone around a crack tip is mapped into the details of the evolutionary phases, supporting the formation of a strongly weak zone in the vicinity of crack tips. Moreover, we recognize sub-micron to micron ruptures with signatures of 'stiffening' in the deformation phase of acoustic-waveforms. We propose that the latter rupture fronts carry critical rupture extensions, including possible dislocations faster than the shear wave speed. Using 'template super-shear waveforms' and their network characteristics, we show that the acoustic emission signals are possible super-shear or intersonic events. Ref. [1] Ghaffari, H. O., and R. P. Young. "Acoustic-Friction Networks and the Evolution of Precursor Rupture Fronts in Laboratory Earthquakes." Nature Scientific reports 3 (2013). [2] Xia, Kaiwen, Ares J. Rosakis, and Hiroo Kanamori. "Laboratory earthquakes: The sub-Rayleigh-to-supershear rupture transition." Science 303.5665 (2004): 1859-1861. [3] Mello, M., et al. "Identifying the unique ground motion signatures of supershear earthquakes: Theory and experiments." Tectonophysics 493.3 (2010): 297-326. [4] Gumbsch, Peter, and Huajian Gao. "Dislocations faster than the speed of sound." Science 283.5404 (1999): 965-968. [5] Livne, Ariel, et al. "The near-tip fields of fast cracks." Science 327.5971 (2010): 1359-1363. [6] Rycroft, Chris H., and Eran Bouchbinder. "Fracture Toughness of Metallic Glasses: Annealing-Induced Embrittlement." Physical review letters 109.19 (2012): 194301. [7] Buehler, Markus J., Farid F. Abraham, and Huajian Gao. "Hyperelasticity governs dynamic fracture at a critical length scale." Nature 426.6963 (2003): 141-146.

  15. Temporal variability of thermal refuges and water temperature patterns in an Atlantic salmon river

    NASA Astrophysics Data System (ADS)

    Dugdale, S.; Bergeron, N.; St-Hilaire, A.

    2013-12-01

    River basins in northern latitudes are predicted to experience increased water temperatures under future climate change. This will have a negative impact on most salmonid populations which are highly intolerant of temperatures in excess of 23° C. In response to summer heat stress, salmonids thermoregulate in discrete units of cold water. Termed thermal refuges, these are of great significance to the ability of salmon and trout to survive increased water temperatures. Although previous research has documented links between the spatial patterns of thermal refuges and salmonid distribution and behaviour, the temporal variability of these cold water units has never been studied. In this investigation, airborne thermal infrared (TIR) imagery acquired six times between 2009 and 2011 was used to characterise temporal variability of thermal refuges and broader scale patterns of water temperature in the Rivière Ouelle, an Atlantic salmon river in Québec, Canada. Thermal refuges detected from TIR imagery were classified into a series of categories, revealing notable inter-survey variability between the absolute counts of each refuge type. Broader-scale longitudinal temperature profiles of river temperature were also extracted. Temporal variability in the absolute counts of lateral groundwater seeps (the most frequently observed thermal refuge class) was shown to correlate strongly with long duration hydrometeorological metrics such as seasonal mean discharge (R2 = 0.94, p < 0.01). Conversely, thermal refuges resulting from cold water tributaries were more temporally stable. Downstream temperature complexity was shown to correlate best with short duration metrics such as cumulative precipitation depth within a 5-day period prior to each survey (R2 = 0.90, p < 0.01). This study is the first of its kind to link thermal refuge dynamics and water temperature patterns to hydrometeorological conditions and may offer valuable insights into how changing hydrometeorological regimes could influence these important cold water units in the future.

  16. Spatio-temporal pattern recognizers using spiking neurons and spike-timing-dependent plasticity.

    PubMed

    Humble, James; Denham, Susan; Wennekers, Thomas

    2012-01-01

    It has previously been shown that by using spike-timing-dependent plasticity (STDP), neurons can adapt to the beginning of a repeating spatio-temporal firing pattern in their input. In the present work, we demonstrate that this mechanism can be extended to train recognizers for longer spatio-temporal input signals. Using a number of neurons that are mutually connected by plastic synapses and subject to a global winner-takes-all mechanism, chains of neurons can form where each neuron is selective to a different segment of a repeating input pattern, and the neurons are feed-forwardly connected in such a way that both the correct input segment and the firing of the previous neurons are required in order to activate the next neuron in the chain. This is akin to a simple class of finite state automata. We show that nearest-neighbor STDP (where only the pre-synaptic spike most recent to a post-synaptic one is considered) leads to "nearest-neighbor" chains where connections only form between subsequent states in a chain (similar to classic "synfire chains"). In contrast, "all-to-all spike-timing-dependent plasticity" (where all pre- and post-synaptic spike pairs matter) leads to multiple connections that can span several temporal stages in the chain; these connections respect the temporal order of the neurons. It is also demonstrated that previously learnt individual chains can be "stitched together" by repeatedly presenting them in a fixed order. This way longer sequence recognizers can be formed, and potentially also nested structures. Robustness of recognition with respect to speed variations in the input patterns is shown to depend on rise-times of post-synaptic potentials and the membrane noise. It is argued that the memory capacity of the model is high, but could theoretically be increased using sparse codes. PMID:23087641

  17. Temporal Analysis of Feeding Patterns of Culex erraticus in Central Alabama

    PubMed Central

    Katholi, Charles R.; Burkett-Cadena, Nathan; Hassan, Hassan K.; Kristensen, Sibylle

    2011-01-01

    Abstract Host blood meals in seven mosquito species previously shown to be infected with eastern equine encephalitis virus at a site in the Tuskegee National Forest in southcentral Alabama were investigated. Of 1374 blood meals derived from 88 different host species collected over 6 years from these seven mosquito species, 1099 were derived from Culex erraticus. Analysis of the temporal pattern of Cx. erraticus meals using a Runs test revealed that the patterns of feeding upon avian and mammalian hosts from March to September of each year were not randomly distributed over time. Similarly, meals taken from the three most commonly targeted host species (yellow-crowned night heron, great blue heron, and white-tailed deer) were not randomly distributed. A Tukey's two-way analysis of variance test demonstrated that although the temporal pattern of meals taken from avian hosts were consistent over the years, the patterns of meals taken from the individual host species were not consistent from year to year. PMID:21395423

  18. Temporal Patterns of Gene Expression in the Antenna of the Adult Drosophila Melanogaster

    PubMed Central

    Helfand, S. L.; Blake, K. J.; Rogina, B.; Stracks, M. D.; Centurion, A.; Naprta, B.

    1995-01-01

    The time course of gene expression in the adult fruit fly has been partially characterized by using enhancer trap and reporter gene constructs that mark 49 different genes. The relative intensity of the reporter protein in individual cells of the antennae was measured as a function of adult age. Most genes showed a graduated expression, and the intensity of expression had a reproducible and characteristic time course. Different genes displayed different temporal patterns of expression and more often than not the pattern of expression was complex. We found a number of genes having patterns that scaled with life span. In these cases the intensity of gene expression was found to be invariant with respect to biological time, when expressed as a fraction of the life span of the line. The scaling was observed even when life span was varied as much as threefold. Such scaling serves to (1) further demonstrate that deterministic mechanisms such as gene regulation act to generate the temporal patterns of expression seen during adult life, (2) indicate that control of these regulatory mechanisms is linked to life span, and (3) suggest mechanisms by which this control is accomplished. We have concluded that gene expression in the adult fly is often regulated in a fashion that allows for graduated expression over time, and that the regulation itself is changing throughout adult life according to some prescribed program or algorithm. PMID:7498736

  19. Similarity breeds proximity: Pattern similarity within and across contexts is related to later mnemonic judgments of temporal proximity

    PubMed Central

    Ezzyat, Youssef; Davachi, Lila

    2014-01-01

    Summary Experiences unfold over time, but little is known about the mechanisms that support the formation of coherent episodic memories for temporally-extended events. Recent work in animals has provided evidence for signals in hippocampus that could link events across temporal gaps, however it is unknown whether and how such signals might be related to later memory for temporal information in humans. We measured patterns of fMRI BOLD activity as people encoded items that were separated in time and manipulated the presence of shared or distinct context across items. We found that hippocampal pattern similarity in the BOLD response across trials predicted later temporal memory decisions when context changed. By contrast, pattern similarity in lateral occipital cortex was related to memory only when context remained stable. These data provide the first evidence in humans that representational stability in hippocampus across time may be a mechanism for temporal memory organization. PMID:24607235

  20. Discrimination and Comprehension of Synthetic Speech by Students with Visual Impairments: The Case of Similar Acoustic Patterns

    ERIC Educational Resources Information Center

    Papadopoulos, Konstantinos; Argyropoulos, Vassilios S.; Kouroupetroglou, Georgios

    2008-01-01

    This study examined the perceptions held by sighted students and students with visual impairments of the intelligibility and comprehensibility of similar acoustic patterns produced by synthetic speech. It determined the types of errors the students made and compared the performance of the two groups on auditory discrimination and comprehension.

  1. PURPOSE: To assess the developmental pattern of vowel acoustics in individuals with Down syndrome (DS) as compared to typically

    E-print Network

    Vorperian, Houri K.

    PURPOSE: To assess the developmental pattern of vowel acoustics in individuals with Down syndrome children and children with Down syndrome Allison Petska, Houri K. Vorperian, and Ray D. Kent Vocal Tract: University of Alberta. Kent, R.D. and Vorperian, H.K. (2013). Speech Impairment in Down Syndrome: A Review. J

  2. Identification of unaspirated plosives using integrated temporal and spectral features in dynamic representation as acoustic cues

    Microsoft Academic Search

    D. Yeung; C. Chan

    1985-01-01

    Using a set of integrated temporal and spectral features to parameterize the consonant regions of C-V syllables, natural Mandarin unaspirated plosives \\/b\\/,\\/d\\/,\\/g\\/,\\/j\\/,\\/zh\\/, and \\/z\\/ were identified satisfactorily when stepwise discriminant function analysis was employed for classification. Out of several different parametric representation methods used, it was found that the highest overall percentage of correct recognition was reached if a dynamic

  3. Microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks

    NASA Astrophysics Data System (ADS)

    Kerner, Boris S.; Klenov, Sergey L.

    2003-09-01

    A microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks due to on-ramps, merge bottlenecks (a reduction of highway lanes), and off-ramps is presented. The basic postulate of three-phase traffic theory is used, which claims that homogeneous (in space and time) model solutions (steady states) of synchronized flow cover a two dimensional region in the flow-density plane [B. S. Kerner, Phys. Rev. Lett. 81, 3797 (1998); Trans. Res. Rec. 1678, 160 (1999)]. Phase transitions leading to diverse congested patterns, pattern evolution, and pattern nonlinear features have been found. Diagrams of congested patterns, i.e., regions of the pattern emergence dependent on traffic demand, have been derived. Diverse effects of metastability with respect to the pattern formation have been found. The microscopic theory allows us to explain the main empirical pattern features at on-ramps and off-ramps which have recently been found [B. S. Kerner, Phys. Rev. E 65, 046138 (2002)]. (i) Rather than moving jams, synchronized flow first occurs at bottlenecks if the flow rate is slowly increasing. Wide moving jams can spontaneously occur only in synchronized flow. (ii) General patterns (GP) and synchronized flow patterns (SP) can spontaneously emerge at the bottlenecks. There can be the widening SP (WSP), the moving SP (MSP), and the localized SP. (iii) At on-ramps cases of “weak” and “strong” congestion should be distinguished. In contrast to weak congestion, under strong congestion the flow rate in synchronized flow in GP reaches a limit flow rate, the frequency of the moving jam emergence reaches a maximum, i.e., the GP characteristics under strong congestion do not depend on traffic demand. (iv) At the off-ramp GP with weak congestion occur. (v) A study of the pattern formation on a highway with two bottlenecks shows that diverse expanded patterns can occur, which cover both bottlenecks. SP first emerged at the downstream bottleneck can be caught at the upstream bottleneck (the catch effect). MSP, WSP, or wide moving jams first emerged at the downstream bottleneck induce diverse patterns at the upstream bottleneck. The onset of congestion at the upstream bottleneck can lead to an intensification of congestion at the downstream bottleneck. This causes a change in the pattern type and/or the pattern features.

  4. Microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks.

    PubMed

    Kerner, Boris S; Klenov, Sergey L

    2003-09-01

    A microscopic theory of spatial-temporal congested traffic patterns at highway bottlenecks due to on-ramps, merge bottlenecks (a reduction of highway lanes), and off-ramps is presented. The basic postulate of three-phase traffic theory is used, which claims that homogeneous (in space and time) model solutions (steady states) of synchronized flow cover a two dimensional region in the flow-density plane [B. S. Kerner, Phys. Rev. Lett. 81, 3797 (1998); Trans. Res. Rec. 1678, 160 (1999)]. Phase transitions leading to diverse congested patterns, pattern evolution, and pattern nonlinear features have been found. Diagrams of congested patterns, i.e., regions of the pattern emergence dependent on traffic demand, have been derived. Diverse effects of metastability with respect to the pattern formation have been found. The microscopic theory allows us to explain the main empirical pattern features at on-ramps and off-ramps which have recently been found [B. S. Kerner, Phys. Rev. E 65, 046138 (2002)]. (i) Rather than moving jams, synchronized flow first occurs at bottlenecks if the flow rate is slowly increasing. Wide moving jams can spontaneously occur only in synchronized flow. (ii) General patterns (GP) and synchronized flow patterns (SP) can spontaneously emerge at the bottlenecks. There can be the widening SP (WSP), the moving SP (MSP), and the localized SP. (iii) At on-ramps cases of "weak" and "strong" congestion should be distinguished. In contrast to weak congestion, under strong congestion the flow rate in synchronized flow in GP reaches a limit flow rate, the frequency of the moving jam emergence reaches a maximum, i.e., the GP characteristics under strong congestion do not depend on traffic demand. (iv) At the off-ramp GP with weak congestion occur. (v) A study of the pattern formation on a highway with two bottlenecks shows that diverse expanded patterns can occur, which cover both bottlenecks. SP first emerged at the downstream bottleneck can be caught at the upstream bottleneck (the catch effect). MSP, WSP, or wide moving jams first emerged at the downstream bottleneck induce diverse patterns at the upstream bottleneck. The onset of congestion at the upstream bottleneck can lead to an intensification of congestion at the downstream bottleneck. This causes a change in the pattern type and/or the pattern features. PMID:14524855

  5. Spatio-temporal soil moisture patterns across gradients of vegetation and topography

    NASA Astrophysics Data System (ADS)

    Hassler, Sibylle; Weiler, Markus; Blume, Theresa

    2014-05-01

    Soil moisture dynamics control hydrological processes on various scales: changes in local water storage and potential activation of preferential flow paths influence connectivity and runoff from hillslopes and ultimately the discharge response of the stream. The spatio-temporal patterns of soil moisture, however, are dependent on a combination of local parameters such as soil type, vegetation and topography as well as meteorological conditions, antecedent moisture and seasonality. In an integrative monitoring study carried out within the CAOS observatory in Luxemburg (http://www.caos-project.de/), soil moisture was measured at 21 sites with 3 soil moisture profiles each. These sites include grassland as well as forest on the one hand and cover different hillslope positions on the other hand. This setup allows us to study both vegetation and topographic effects. The spatio-temporal patterns of soil moisture were analysed using two approaches: 1) we examined temporal persistence of soil moisture patterns with rank stability plots and addressed the variability within and between sites for contrasting meteorological conditions. 2) In a next step we focused on specific hydrologic events: two periods during summer recession were distinguished, first the drying out of the soils during a period of no precipitation, but also the continuing decline even after summer rains have started. Furthermore, the soil moisture response to three different rainfall events was examined, varying in intensity and antecedent moisture conditions. The emerging contrasts in patterns were put into context of site-specific characteristics such as vegetation and topographical position to identify controls on soil moisture dynamics for our range of sites. Ultimately, linking similarity in soil moisture response in landscapes to these controls can elucidate the hydrological functioning of landscape units and thus facilitate modelling efforts.

  6. TEMPORAL PATTERNS IN THREE-DIMENSIONAL STRUCTURE AND ACTIVITY OF SCHOOLS OF THE ATLANTIC SILVERSIDE 'MENIDIA MENIDIA'

    EPA Science Inventory

    Temporal patterns in the structure and activity of schools of the Atlantic silverside Menidia menidia were investigated under laboratory conditions using a new computerized video technique for three-dimensional analysis. Fish were collected by seining at Middle Bridge, Pettaquans...

  7. Controls of initial topography on temporal and spatial patterns of glacial erosion

    NASA Astrophysics Data System (ADS)

    Pedersen, Vivi K.; Huismans, Ritske S.; Herman, Frédéric; Egholm, David L.

    2014-10-01

    Here we investigate the influence of initial pre-glacial topography on spatial and temporal patterns of glacial erosion using numerical surface process modelling, including a higher order ice sheet model. First, we consider glacier dynamics when simulating glaciation in two real landscapes, representing plateau-type topography (southeast Australia) and characteristic steady-state fluvial topography (southern Taiwan). We find that the different initial landscape configurations result in distinctly different ice configurations and patterns of basal sliding. The sliding patterns are controlled by ice configuration and the resulting basal shear stresses and by the thermal properties at the base of the ice. We then investigate how these characteristic patterns of basal sliding control glacial erosion and long-term landscape evolution using synthetic representations of the two landscapes. The two landscape configurations result in markedly different spatial and temporal patterns of glacial erosion. However, the resulting landscapes may have similar morphology, irrespective of initial landscapes and glacial erosion patterns being significantly different. The numerical experiments also suggest that, in addition to basal temperature, basal shear stress is important in restricting long-term glacial erosion, which is relevant for the preservation of landforms during glaciations. Specifically, pre-glacial landforms may be eroded although they are initially protected by cold-based ice, when the ice configuration promotes significant basal shear stress (glacial erosion) at the edge of a plateau-like landscape. In contrast, pre-glacial landforms may be preserved irrespective of the ice being warm-based, when low gradients in the ice surface act to limit basal shear stress.

  8. Temporal Changes in Eruptive Behavior at Fuego Volcano, Guatemala Identified with Seismic Coda Wave Interferometry and Seismo-acoustic Observations

    NASA Astrophysics Data System (ADS)

    Erdem, J.; Waite, G. P.

    2011-12-01

    Fuego Volcano (14°29'N, 90°53'W, 3800m) is the southernmost vent of the north-south trending Fuego-Acatenango volcanic complex. A basaltic-andesite stratovolcano, Fuego has had more than 60 sub-plinian eruptions since 1524 AD, making it one of the most active volcanoes in the world. Since 1999 Fuego has exhibited continuous low-level activity, which alternates between periods of lava effusion with strombolian explosions and periods of discrete explosions with no lava effusion. We analyzed 138 explosions recorded on a broadband seismometer and infrasonic microphones from 7 to 14 June 2008 at a distance of 7.5 km from the vent. During the observation period, a new lava flow began. Additional observations were made at a distance of 1 km between 27 June and 1 July 2008. The explosions were identified through a combination of visual field observations and the examination of infrasound records. Acoustic waveform cross-correlation indicated a highly repetitive source appropriate for investigating temporal variations in the wavefield. We measured variations in seismic and acoustic wave arrival time differences in the range of 0.5 s for the more distant station, which might occur as a result of variations in source depth, for example. However, after examining a wind speed model for the region, we find that wind speed variations are more likely to explain the delays. We also detected short-term relative changes in the velocity structure ranging from -0.23% to 0.61% at the distant station and -0.8% to 0.7% at the closer station using seismic coda wave interferometry. This rapid variation, sometimes changing by 0.23% in 90 minutes, may indicate minor fluctuations in volatile content.

  9. Temporal and spatial patterns in vegetation and atmospheric properties from AVIRIS

    SciTech Connect

    Roberts, D.A. [Univ. of California, Santa Barbara, CA (United States). Dept. of Geography] [Univ. of California, Santa Barbara, CA (United States). Dept. of Geography; Green, R.O. [Univ. of California, Santa Barbara, CA (United States). Dept. of Geography] [Univ. of California, Santa Barbara, CA (United States). Dept. of Geography; [Jet Propulsion Labs., Pasadena, CA (United States); Adams, J.B. [Univ. of Washington, Seattle, WA (United States). Dept. of Geological Sciences] [Univ. of Washington, Seattle, WA (United States). Dept. of Geological Sciences

    1997-12-01

    Little research has focused on the use of imaging spectrometry for change detection. In this paper, the authors apply Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data to the monitoring of seasonal changes in atmospheric water vapor, liquid water, and surface cover in the vicinity of the Jasper Ridge, CA, for three dates in 1992. Apparent surface reflectance was retrieved and water vapor and liquid water mapped by using a radiative-transfer-based inversion that accounts for spatially variable atmospheres. Spectral mixture analysis (SMA) was used to model reflectance data as mixtures of green vegetation (GV), nonphotosynthetic vegetation (NPV), soil, and shade. Temporal and spatial patterns in endmember fractions and liquid water were compared to the normalized difference vegetation index (NDVI). The reflectance retrieval algorithm was tested by using a temporally invariant target.

  10. Heterogeneity in hotspots: spatio-temporal patterns in neglected parasitic diseases.

    PubMed

    Lal, A; Hales, S

    2015-02-01

    Cryptosporidiosis and giardiasis have been recognized by the WHO as 'Neglected Diseases'. Minimal attention has been paid to the spatial and temporal distribution of disease incidence patterns. Using disease notification data, we detected spatio-temporal clusters of cryptosporidiosis and giardiasis across three time periods: (i) 1997-2000, (ii) 2001-2004, (iii) 2005-2008. There was substantial variation in the geographical location and timing of recurrent cryptosporidiosis and giardiasis clusters. Statistically significant (P < 0·05) giardiasis clusters tended to occur in predominantly urban areas with little apparent seasonal influence, while statistically significant cryptosporidiosis clusters were detected in spring, in areas with high livestock land use. The location and timing of cryptosporidiosis clusters suggest an influence of livestock production practices, while urban exposures and host behaviour are likely to influence giardiasis clusters. This approach provides a resource-efficient method for public health authorities to prioritize future research needs and areas for intervention. PMID:24819745

  11. Spatial and Temporal Patterns of Carbon Storage in Forest Ecosystems on Hainan Island, Southern China

    PubMed Central

    Tang, Xuli; Zhang, Qianmei; Wang, Dong; Yuan, Lianlian; Chen, Xubing

    2014-01-01

    Spatial and temporal patterns of carbon (C) storage in forest ecosystems significantly affect the terrestrial C budget, but such patterns are unclear in the forests in Hainan Province, the largest tropical island in China. Here, we estimated the spatial and temporal patterns of C storage from 1993–2008 in Hainan's forest ecosystems by combining our measured data with four consecutive national forest inventories data. Forest coverage increased from 20.7% in the 1950s to 56.4% in the 2010s. The average C density of 163.7 Mg C/ha in Hainan's forest ecosystems in this study was slightly higher than that of China's mainland forests, but was remarkably lower than that in the tropical forests worldwide. Total forest ecosystem C storage in Hainan increased from 109.51 Tg in 1993 to 279.17 Tg in 2008. Soil C accounted for more than 70% of total forest ecosystem C. The spatial distribution of forest C storage in Hainan was uneven, reflecting differences in land use change and forest management. The potential carbon sequestration of forest ecosystems was 77.3 Tg C if all forested lands were restored to natural tropical forests. To increase the C sequestration potential on Hainan Island, future forest management should focus on the conservation of natural forests, selection of tree species, planting of understory species, and implementation of sustainable practices. PMID:25229628

  12. Spatial and temporal patterns of carbon storage in forest ecosystems on Hainan island, southern China.

    PubMed

    Ren, Hai; Li, Linjun; Liu, Qiang; Wang, Xu; Li, Yide; Hui, Dafeng; Jian, Shuguang; Wang, Jun; Yang, Huai; Lu, Hongfang; Zhou, Guoyi; Tang, Xuli; Zhang, Qianmei; Wang, Dong; Yuan, Lianlian; Chen, Xubing

    2014-01-01

    Spatial and temporal patterns of carbon (C) storage in forest ecosystems significantly affect the terrestrial C budget, but such patterns are unclear in the forests in Hainan Province, the largest tropical island in China. Here, we estimated the spatial and temporal patterns of C storage from 1993-2008 in Hainan's forest ecosystems by combining our measured data with four consecutive national forest inventories data. Forest coverage increased from 20.7% in the 1950s to 56.4% in the 2010s. The average C density of 163.7 Mg C/ha in Hainan's forest ecosystems in this study was slightly higher than that of China's mainland forests, but was remarkably lower than that in the tropical forests worldwide. Total forest ecosystem C storage in Hainan increased from 109.51 Tg in 1993 to 279.17 Tg in 2008. Soil C accounted for more than 70% of total forest ecosystem C. The spatial distribution of forest C storage in Hainan was uneven, reflecting differences in land use change and forest management. The potential carbon sequestration of forest ecosystems was 77.3 Tg C if all forested lands were restored to natural tropical forests. To increase the C sequestration potential on Hainan Island, future forest management should focus on the conservation of natural forests, selection of tree species, planting of understory species, and implementation of sustainable practices. PMID:25229628

  13. Distinct Mechanisms for Synchronization and Temporal Patterning of Odor-Encoding Neural Assemblies

    NASA Astrophysics Data System (ADS)

    MacLeod, Katrina; Laurent, Gilles

    1996-11-01

    Stimulus-evoked oscillatory synchronization of neural assemblies and temporal patterns of neuronal activity have been observed in many sensory systems, such as the visual and auditory cortices of mammals or the olfactory system of insects. In the locust olfactory system, single odor puffs cause the immediate formation of odor-specific neural assemblies, defined both by their transient synchronized firing and their progressive transformation over the course of a response. The application of an antagonist of ionotropic ?-aminobutyric acid (GABA) receptors to the first olfactory relay neuropil selectively blocked the fast inhibitory synapse between local and projection neurons. This manipulation abolished the synchronization of the odor-coding neural ensembles but did not affect each neuron's temporal response patterns to odors, even when these patterns contained periods of inhibition. Fast GABA-mediated inhibition, therefore, appears to underlie neuronal synchronization but not response tuning in this olfactory system. The selective desynchronization of stimulus-evoked oscillating neural assemblies in vivo is now possible, enabling direct functional tests of their significance for sensation and perception.

  14. Vision based forest smoke detection using analyzing of temporal patterns of smoke and their probability models

    NASA Astrophysics Data System (ADS)

    Ham, SunJae; Ko, Byoung-Chul; Nam, Jae-Yeal

    2011-03-01

    In general, since smoke appears before flames, smoke detection is particularly important for early fire detection systems. To detect fire-smoke using video camera is a difficult work because main characteristics of a smoke are uncertain, vague, constant patterns of shape and color. Thus, this paper proposes a new fire-smoke detection method, especially forest smoke using analyzing of temporal patterns of smoke and Fuzzy Finite Automata (FFA). To consider the smoke characteristics over time, the temporal patterns of intensity entropy, wavelet energy and motion orientation have been used for generating, multivariate probability density functions (PDFs) are applied Fuzzy Finite Automata (FFA) for smoke verification. The proposed FFA consist of a set of fuzzy states (VH, H, L, VL), and a transition mapping that describes what event can occur at which state and resulting new state. For smoke verification, FFA is most appropriate method in case variables are time-dependent and uncertain. The proposed algorithm is successfully applied to various fire-smoke videos and shows a better detection performance.

  15. Acoustic effects of a superior semicircular canal dehiscence: a temporal bone study.

    PubMed

    Luers, J C; Pazen, D; Meister, H; Lauxmann, M; Eiber, A; Beutner, D; Hüttenbrink, K B

    2015-03-01

    A dehiscence of the superior semicircular canal is said to be responsible for a number of specific and unspecific ear symptoms and possible a conductive hearing loss of up to 40 dB. As in vivo a dehiscence would not be opened against air, but is naturally patched with dura and the brain, it was our aim to investigate the effects of an superior semicircular canal dehiscence on the air conduction hearing in fresh human temporal bones with different boundary conditions. At ten fresh human temporal bones, we investigated the transmission of sound energy through the middle and inner ear using a round window microphone and laser Doppler vibrometer for perilymph motions inside the dehiscence. After baseline measurements, the superior semicircular canal was opened. We investigated the change of the transfer function when the canal is opened against air (pressure equivalent water column), against a water column and when it is patched with a layer of dura. Opening the superior semicircular canal resulted in a loss of sound transmission of maximal 10-15 dB only in frequencies below 1 kHz. When covering the dehiscence with a water column, the conductive hearing component was reduced to 6-8 dB. Placing a dura patch on top of the dehiscence resulted in a normalization of the transfer function. If our experiments are consistent with the conditions in vivo, then superior semicircular canal dehiscence does not lead to an extensive and clinically considerable conductive air conduction component. PMID:24381023

  16. Investigation of properties of surface acoustic waves generated by periodically patterned ZnO on silicon substrate.

    PubMed

    Sai Krishna Santosh, G; Nemade, Harshal B

    2015-05-01

    The paper presents the characteristics of vertically polarized surface waves generated in silicon substrate by acoustic coupling of bulk waves excited in a periodically patterned ZnO film on silicon. The finite element simulations are performed on the proposed patterned-ZnO/Si structure and vertically polarized modes in silicon are found to be dominant in the frequency dependent analysis. The generated modes in silicon are concentrated near the surface within a wavelength depth and exhibit surface wave properties. Dispersion curves of phase velocity and coupling coefficient for the surface modes are reported. The results indicate high electromechanical coupling coefficient of 6.4% as well as high phase velocity of 5332m/s for the surface mode generated in silicon owing to the acoustic coupling of the first order bulk mode in ZnO pattern observed at ZnO height to wavelength ratio of 0.19. PMID:25677540

  17. Signaling Pathways Involved in Striatal Synaptic Plasticity are Sensitive to Temporal Pattern and Exhibit Spatial Specificity

    PubMed Central

    Kim, BoHung; Hawes, Sarah L.; Gillani, Fawad; Wallace, Lane J.; Blackwell, Kim T.

    2013-01-01

    The basal ganglia is a brain region critically involved in reinforcement learning and motor control. Synaptic plasticity in the striatum of the basal ganglia is a cellular mechanism implicated in learning and neuronal information processing. Therefore, understanding how different spatio-temporal patterns of synaptic input select for different types of plasticity is key to understanding learning mechanisms. In striatal medium spiny projection neurons (MSPN), both long term potentiation (LTP) and long term depression (LTD) require an elevation in intracellular calcium concentration; however, it is unknown how the post-synaptic neuron discriminates between different patterns of calcium influx. Using computer modeling, we investigate the hypothesis that temporal pattern of stimulation can select for either endocannabinoid production (for LTD) or protein kinase C (PKC) activation (for LTP) in striatal MSPNs. We implement a stochastic model of the post-synaptic signaling pathways in a dendrite with one or more diffusionally coupled spines. The model is validated by comparison to experiments measuring endocannabinoid-dependent depolarization induced suppression of inhibition. Using the validated model, simulations demonstrate that theta burst stimulation, which produces LTP, increases the activation of PKC as compared to 20 Hz stimulation, which produces LTD. The model prediction that PKC activation is required for theta burst LTP is confirmed experimentally. Using the ratio of PKC to endocannabinoid production as an index of plasticity direction, model simulations demonstrate that LTP exhibits spine level spatial specificity, whereas LTD is more diffuse. These results suggest that spatio-temporal control of striatal information processing employs these Gq coupled pathways. PMID:23516346

  18. Spatio-temporal foraging patterns of a giant zooplanktivore, the leatherback turtle

    NASA Astrophysics Data System (ADS)

    Fossette, Sabrina; Hobson, Victoria J.; Girard, Charlotte; Calmettes, Beatriz; Gaspar, Philippe; Georges, Jean-Yves; Hays, Graeme C.

    2010-05-01

    Understanding food web functioning through the study of natural bio-indicators may constitute a valuable and original approach. In the context of jellyfish proliferation in many overexploited marine ecosystems studying the spatio-temporal foraging patterns of the giant "jellyvore" leatherback turtle turns out to be particularly relevant. Here we analyzed long-term tracking data to assess spatio-temporal foraging patterns in 21 leatherback turtles during their pluri-annual migration in the Northern Atlantic. Through an analytical approach based on the animal's own motion (independent of currents) and diving behavior distinct zones of high and low foraging success were identified. High foraging success occurred in a sub-equatorial zone spanning the width of the Atlantic and at high (>30°N) latitudes. Between these zones in the centre of North Atlantic gyre there was low foraging success. This "ocean desert" area was traversed at high speed by leatherbacks on their way to more productive areas at higher latitudes. Animals traveled slowly in high foraging success areas and dived shallower (17.2 ± 8.0 km day - 1 and 53.6 ± 33.1 m mean ± SD respectively) than in low foraging success areas (51.0 ± 13.1 km day - 1 and 81.8 ± 56.2 m mean ± SD respectively). These spatio-temporal foraging patterns seem to relatively closely match the main features of the integrated meso-zooplankton distribution in the North Atlantic. Our method of defining high foraging success areas is intuitive and relatively easy to implement but also takes into account the impact of oceanic currents on animal's behavior.

  19. Spatial and temporal variability of plankton stocks from acoustic backscatter intensity and direct measurements in the northeastern Gulf of Mexico

    E-print Network

    Scott, Rebecca Lee

    2001-01-01

    between acoustic backscatter intensity and current velocity vary with the movement of warm slope eddies and other mesoscale circulation features in the Gulf. Wind mixing associated with hurricane-strength storm events appears to affect the acoustic...

  20. Spatial and temporal patterns of dengue in guangdong province of china.

    PubMed

    Wang, Chenggang; Yang, Weizhong; Fan, Jingchun; Wang, Furong; Jiang, Baofa; Liu, Qiyong

    2015-03-01

    The aim of the study was to describe the spatial and temporal patterns of dengue in Guangdong for 1978 to 2010. Time series analysis was performed using data on annual dengue incidence in Guangdong province for 1978-2010. Annual average dengue incidences for each city were mapped for 4 periods by using the geographical information system (GIS). Hot spot analysis was used to identify spatial patterns of dengue cases for 2005-2010 by using the CrimeStat III software. The incidence of dengue in Guangdong province had fallen steadily from 1978 to 2010. The time series was a random sequence without regularity and with no fixed cycle. The geographic range of dengue fever had expanded from 1978 to 2010. Cases were mostly concentrated in Zhanjiang and the developed regions of Pearl River Delta and Shantou. PMID:23467628

  1. Knowledge-level querying of temporal patterns in clinical research systems.

    PubMed

    O'Connor, Martin J; Shankar, Ravi D; Parrish, David B; Das, Amar K

    2007-01-01

    Managing time-stamped data is essential to clinical research activities and often requires the use of considerable domain knowledge. Adequately representing this domain knowledge is difficult in relational database systems. As a result, there is a need for principled methods to overcome the disconnect between the database representation of time-oriented research data and corresponding knowledge of domain-relevant concepts. In this paper, we present a set of methodologies for undertaking knowledge level querying of temporal patterns, and discuss its application to the verification of temporal constraints in clinical-trial applications. Our approach allows knowledge generated from query results to be tied to the data and, if necessary, used for further inference. We show how the Semantic Web ontology and rule languages, OWL and SWRL, respectively, can support the temporal knowledge model needed to integrate low-level representations of relational data with high-level domain concepts used in research data management. We present a scalable bridge-based software architecture that uses this knowledge model to enable dynamic querying of time-oriented research data. PMID:17911729

  2. Different response patterns between auditory spectral and spatial temporal order judgment (TOJ).

    PubMed

    Fostick, Leah; Babkoff, Harvey

    2013-01-01

    Temporal order judgment (TOJ) thresholds have been widely reported as valid estimates of the temporal disparity necessary for correctly identifying the order of two stimuli. Data for two auditory TOJ paradigms are often reported in the literature: (1) spatially-based TOJ in which the order of presentation of the same stimulus to the right and left ear differs; and (2) spectrally-based TOJ in which the order of two stimuli differing in frequency is presented to one ear or to both ears simultaneously. Since the thresholds reported using the two paradigms differ, the aim of the current study was to compare their response patterns. The results from three different experiments showed that: (1) while almost none of the participants were able to perform the spatial TOJ task when ISI = 5 ms, with the spectral task, 50% reached an accuracy level of 75% when ISI = 5 ms; (2) temporal separation was only a partial predictor for performance in the spectral task, while it fully predicted performance in the spatial task; and (3) training improved performance markedly in the spectral TOJ task, but had no effect on spatial TOJ. These results suggest that the two paradigms may reflect different perceptual mechanisms. PMID:23820944

  3. Spatial and temporal patterns of hydrologic connectivity between upland landscapes and stream networks (Invited)

    NASA Astrophysics Data System (ADS)

    McGlynn, B. L.; Nippgen, F.; Jencso, K. G.; Emanuel, R. E.

    2013-12-01

    Congress enacted the Clean Water Act (CWA) 'to restore and maintain the chemical, physical, and biological integrity of the Nation's waters'. A recent Supreme Court decision further described protection for waters with 'a significant nexus to navigable waters" if they are in the same watershed and have an effect on the chemical, physical, or biological integrity of traditional navigable waters or interstate waters that is more than 'speculative or insubstantial.' Evolving interpretation of the CWA and 'significant nexus' (connectivity) requires investigation and understanding of the spatial and temporal patterns of hydrologic connectivity between upland landscapes and stream networks that mediate streamflow magnitude and composition. While hydrologic connectivity is a continuum, strong non-linearities including the shift from unsaturated to saturated flow conditions lead to threshold or transient connectivity behavior and orders of magnitude changes in flow velocities and source water compositions. Here we illustrate the spatial and temporal dynamics of hydrologic connectivity between upland landscapes and stream networks that provide direct and proximate links between streamflow composition and its watershed sources. We suggest that adjacency alone does not determine influence on hydrologic response and streamwater composition and that new understanding and communication of the temporal and spatial dynamics of watershed connectivity are required to address urgent needs at the interface of the CWA, science, and society.

  4. Fire, native species, and soil resource interactions influence the spatio-temporal invasion pattern of Bromus tectorum

    Microsoft Academic Search

    Michael J. Gundale; Steve Sutherland; Thomas H. DeLuca

    2008-01-01

    Bromus tectorum (cheatgrass) is an invasive annual that occupies perennial grass and shrub communities throughout the western United States. Bromus tectorum exhibits an intriguing spatio-temporal pattern of invasion in low elevation ponderosa pine Pinus ponderosa\\/bunchgrass communities in western Montana where it forms dense rings beneath solitary pines following fire. This pattern provides a unique opportunity to investigate several indirect effects

  5. Dynamic evolving spiking neural networks for on-line spatio- and spectro-temporal pattern recognition.

    PubMed

    Kasabov, Nikola; Dhoble, Kshitij; Nuntalid, Nuttapod; Indiveri, Giacomo

    2013-05-01

    On-line learning and recognition of spatio- and spectro-temporal data (SSTD) is a very challenging task and an important one for the future development of autonomous machine learning systems with broad applications. Models based on spiking neural networks (SNN) have already proved their potential in capturing spatial and temporal data. One class of them, the evolving SNN (eSNN), uses a one-pass rank-order learning mechanism and a strategy to evolve a new spiking neuron and new connections to learn new patterns from incoming data. So far these networks have been mainly used for fast image and speech frame-based recognition. Alternative spike-time learning methods, such as Spike-Timing Dependent Plasticity (STDP) and its variant Spike Driven Synaptic Plasticity (SDSP), can also be used to learn spatio-temporal representations, but they usually require many iterations in an unsupervised or semi-supervised mode of learning. This paper introduces a new class of eSNN, dynamic eSNN, that utilise both rank-order learning and dynamic synapses to learn SSTD in a fast, on-line mode. The paper also introduces a new model called deSNN, that utilises rank-order learning and SDSP spike-time learning in unsupervised, supervised, or semi-supervised modes. The SDSP learning is used to evolve dynamically the network changing connection weights that capture spatio-temporal spike data clusters both during training and during recall. The new deSNN model is first illustrated on simple examples and then applied on two case study applications: (1) moving object recognition using address-event representation (AER) with data collected using a silicon retina device; (2) EEG SSTD recognition for brain-computer interfaces. The deSNN models resulted in a superior performance in terms of accuracy and speed when compared with other SNN models that use either rank-order or STDP learning. The reason is that the deSNN makes use of both the information contained in the order of the first input spikes (which information is explicitly present in input data streams and would be crucial to consider in some tasks) and of the information contained in the timing of the following spikes that is learned by the dynamic synapses as a whole spatio-temporal pattern. PMID:23340243

  6. BaySTDetect: detecting unusual temporal patterns in small area data via Bayesian model choice.

    PubMed

    Li, Guangquan; Best, Nicky; Hansell, Anna L; Ahmed, Ismaïl; Richardson, Sylvia

    2012-09-01

    Space-time modeling of small area data is often used in epidemiology for mapping chronic disease rates and by government statistical agencies for producing local estimates of, for example, unemployment or crime rates. Although there is typically a general temporal trend, which affects all areas similarly, abrupt changes may occur in a particular area, e.g. due to emergence of localized predictors/risk factor(s) or impact of a new policy. Detection of areas with "unusual" temporal patterns is therefore important as a screening tool for further investigations. In this paper, we propose BaySTDetect, a novel detection method for short-time series of small area data using Bayesian model choice between two competing space-time models. The first model is a multiplicative decomposition of the area effect and the temporal effect, assuming one common temporal pattern across the whole study region. The second model estimates the time trends independently for each area. For each area, the posterior probability of belonging to the common trend model is calculated, which is then used to classify the local time trend as unusual or not. Crucial to any detection method, we provide a Bayesian estimate of the false discovery rate (FDR). A comprehensive simulation study has demonstrated the consistent good performance of BaySTDetect in detecting various realistic departure patterns in addition to estimating well the FDR. The proposed method is applied retrospectively to mortality data on chronic obstructive pulmonary disease (COPD) in England and Wales between 1990 and 1997 (a) to test a hypothesis that a government policy increased the diagnosis of COPD and (b) to perform surveillance. While results showed no evidence supporting the hypothesis regarding the policy, an identified unusual district (Tower Hamlets in inner London) was later recognized to have higher than national rates of hospital readmission and mortality due to COPD by the National Health Service, which initiated various local enhanced services to tackle the problem. Our method would have led to an early detection of this local health issue. PMID:22452805

  7. Fish and Phytoplankton Exhibit Contrasting Temporal Species Abundance Patterns in a Dynamic North Temperate Lake

    PubMed Central

    Hansen, Gretchen J. A.; Carey, Cayelan C.

    2015-01-01

    Temporal patterns of species abundance, although less well-studied than spatial patterns, provide valuable insight to the processes governing community assembly. We compared temporal abundance distributions of two communities, phytoplankton and fish, in a north temperate lake. We used both 17 years of observed relative abundance data as well as resampled data from Monte Carlo simulations to account for the possible effects of non-detection of rare species. Similar to what has been found in other communities, phytoplankton and fish species that appeared more frequently were generally more abundant than rare species. However, neither community exhibited two distinct groups of “core” (common occurrence and high abundance) and “occasional” (rare occurrence and low abundance) species. Both observed and resampled data show that the phytoplankton community was dominated by occasional species appearing in only one year that exhibited large variation in their abundances, while the fish community was dominated by core species occurring in all 17 years at high abundances. We hypothesize that the life-history traits that enable phytoplankton to persist in highly dynamic environments may result in communities dominated by occasional species capable of reaching high abundances when conditions allow. Conversely, longer turnover times and broad environmental tolerances of fish may result in communities dominated by core species structured primarily by competitive interactions. PMID:25651399

  8. Spatial and temporal patterns of enzootic raccoon rabies adjusted for multiple covariates

    PubMed Central

    Recuenco, Sergio; Eidson, Millicent; Kulldorff, Martin; Johnson, Glen; Cherry, Bryan

    2007-01-01

    Background With the objective of identifying spatial and temporal patterns of enzootic raccoon variant rabies, a spatial scan statistic was utilized to search for significant terrestrial rabies clusters by year in New York State in 1997–2003. Cluster analyses were unadjusted for other factors, adjusted for covariates, and adjusted for covariates and large scale geographic variation (LSGV). Adjustments were intended to identify the unusual aggregations of cases given the expected distribution based on the observed locations. Results Statistically significant clusters were identified particularly in the Albany, Finger Lakes, and South Hudson areas. The clusters were generally persistent in the Albany area, but demonstrated cyclical changes in rabies activity every few years in the other areas. Cluster adjustments allowed the discussion of possible causes for the high risk raccoon rabies areas identified. Conclusion This study analyzed raccoon variant rabies spatial and temporal patterns in New York that have not been previously described at a focal (census tract) level. Comparisons across the type of spatial analysis performed with various degrees of adjustment allow consideration of the potential influence of geographical factors for raccoon rabies and possible reasons for the highest risk areas (statistically significant clusters). PMID:17428324

  9. Temporal patterns of genetic and phenotypic variation in the epidemiologically important drone fly, Eristalis tenax.

    PubMed

    Francuski, Lj; Mati?, I; Ludoški, J; Milankov, V

    2011-06-01

    Eristalis tenax L. (Diptera: Syrphidae) is commonly known as the drone fly (adult) or rat-tailed maggot (immature). Both adults and immature stages are identified as potential mechanical vectors of mycobacterial pathogens, and early-stage maggots cause accidental myiasis. We compared four samples from Mount Fruška Gora, Serbia, with the aim of obtaining insights into the temporal variations and sexual dimorphism in the species. This integrative approach was based on allozyme loci, morphometric wing parameters (shape and size) and abdominal colour patterns. Consistent sexual dimorphism was observed, indicating that male specimens had lighter abdomens and smaller and narrower wings than females. The distribution of genetic diversity at polymorphic loci indicated genetic divergence among collection dates. Landmark-based geometric morphometrics revealed, contrary to the lack of divergence in wing size, significant wing shape variation throughout the year. In addition, temporal changes in the frequencies of the abdominal patterns observed are likely to relate to the biology of the species and ecological factors in the locality. Hence, the present study expands our knowledge of the genetic diversity and phenotypic plasticity of E. tenax. The quantification of such variability represents a step towards the evaluation of the adaptive potential of this species of medical and epidemiological importance. PMID:21414022

  10. Fish and phytoplankton exhibit contrasting temporal species abundance patterns in a dynamic north temperate lake.

    PubMed

    Hansen, Gretchen J A; Carey, Cayelan C

    2015-01-01

    Temporal patterns of species abundance, although less well-studied than spatial patterns, provide valuable insight to the processes governing community assembly. We compared temporal abundance distributions of two communities, phytoplankton and fish, in a north temperate lake. We used both 17 years of observed relative abundance data as well as resampled data from Monte Carlo simulations to account for the possible effects of non-detection of rare species. Similar to what has been found in other communities, phytoplankton and fish species that appeared more frequently were generally more abundant than rare species. However, neither community exhibited two distinct groups of "core" (common occurrence and high abundance) and "occasional" (rare occurrence and low abundance) species. Both observed and resampled data show that the phytoplankton community was dominated by occasional species appearing in only one year that exhibited large variation in their abundances, while the fish community was dominated by core species occurring in all 17 years at high abundances. We hypothesize that the life-history traits that enable phytoplankton to persist in highly dynamic environments may result in communities dominated by occasional species capable of reaching high abundances when conditions allow. Conversely, longer turnover times and broad environmental tolerances of fish may result in communities dominated by core species structured primarily by competitive interactions. PMID:25651399

  11. Spatio-Temporal Patterns of Key Exploited Marine Species in the Northwestern Mediterranean Sea

    PubMed Central

    Morfin, Marie; Fromentin, Jean-Marc; Jadaud, Angélique; Bez, Nicolas

    2012-01-01

    This study analyzes the temporal variability/stability of the spatial distributions of key exploited species in the Gulf of Lions (Northwestern Mediterranean Sea). To do so, we analyzed data from the MEDITS bottom-trawl scientific surveys from 1994 to 2010 at 66 fixed stations and selected 12 key exploited species. We proposed a geostatistical approach to handle zero-inflated and non-stationary distributions and to test for the temporal stability of the spatial structures. Empirical Orthogonal Functions and other descriptors were then applied to investigate the temporal persistence and the characteristics of the spatial patterns. The spatial structure of the distribution (i.e. the pattern of spatial autocorrelation) of the 12 key species studied remained highly stable over the time period sampled. The spatial distributions of all species obtained through kriging also appeared to be stable over time, while each species displayed a specific spatial distribution. Furthermore, adults were generally more densely concentrated than juveniles and occupied areas included in the distribution of juveniles. Despite the strong persistence of spatial distributions, we also observed that the area occupied by each species was correlated to its abundance: the more abundant the species, the larger the occupation area. Such a result tends to support MacCall's basin theory, according to which density-dependence responses would drive the expansion of those 12 key species in the Gulf of Lions. Further analyses showed that these species never saturated their habitats, suggesting that they are below their carrying capacity; an assumption in agreement with the overexploitation of several of these species. Finally, the stability of their spatial distributions over time and their potential ability to diffuse outside their main habitats give support to Marine Protected Areas as a potential pertinent management tool. PMID:22655079

  12. Coexistence of productive and non-productive populations by fluctuation-driven spatio-temporal patterns.

    PubMed

    Behar, Hilla; Brenner, Naama; Louzoun, Yoram

    2014-09-01

    Cooperative interactions, their stability and evolution, provide an interesting context in which to study the interface between cellular and population levels of organization. Here we study a public goods model relevant to microorganism populations actively extracting a growth resource from their environment. Cells can display one of two phenotypes - a productive phenotype that extracts the resources at a cost, and a non-productive phenotype that only consumes the same resource. Both proliferate and are free to move by diffusion; growth rate and diffusion coefficient depend only weakly phenotype. We analyze the continuous differential equation model as well as simulate stochastically the full dynamics. We find that the two sub-populations, which cannot coexist in a well-mixed environment, develop spatio-temporal patterns that enable long-term coexistence in the shared environment. These patterns are purely fluctuation-driven, as the corresponding continuous spatial system does not display Turing instability. The average stability of coexistence patterns derives from a dynamic mechanism in which the producing sub-population equilibrates with the environmental resource and holds it close to an extinction transition of the other sub-population, causing it to constantly hover around this transition. Thus the ecological interactions support a mechanism reminiscent of self-organized criticality; power-law distributions and long-range correlations are found. The results are discussed in the context of general pattern formation and critical behavior in ecology as well as in an experimental context. PMID:25058368

  13. Temporal Links in Daily Activity Patterns between Coral Reef Predators and Their Prey

    PubMed Central

    Bosiger, Yoland J.; McCormick, Mark I.

    2014-01-01

    Few studies have documented the activity patterns of both predators and their common prey over 24 h diel cycles. This study documents the temporal periodicity of two common resident predators of juvenile reef fishes, Cephalopholis cyanostigma (rockcod) and Pseudochromis fuscus (dottyback) and compares these to the activity and foraging pattern of a common prey species, juvenile Pomacentrus moluccensis (lemon damselfish). Detailed observations of activity in the field and using 24 h infrared video in the laboratory revealed that the two predators had very different activity patterns. C. cyanostigma was active over the whole 24 h period, with a peak in feeding strikes at dusk and increased activity at both dawn and dusk, while P. fuscus was not active at night and had its highest strike rates at midday. The activity and foraging pattern of P. moluccensis directly opposes that of C. cyanostigma with individuals reducing strike rate and intraspecific aggression at both dawn and dusk, and reducing distance from shelter and boldness at dusk only. Juveniles examined were just outside the size-selection window of P. fuscus. We suggest that the relatively predictable diel behaviour of coral reef predators results from physiological factors such as visual sensory abilities, circadian rhythmicity, variation in hunting profitability, and predation risk at different times of the day. Our study suggests that the diel periodicity of P. moluccensis behaviour may represent a response to increased predation risk at times when both the ability to efficiently capture food and visually detect predators is reduced. PMID:25354096

  14. Timescales of Multineuronal Activity Patterns Reflect Temporal Structure of Visual Stimuli

    PubMed Central

    Jurju?, Ovidiu F.; Nikoli?, Danko; Singer, Wolf; Yu, Shan; Havenith, Martha N.; Mure?an, Raul C.

    2011-01-01

    The investigation of distributed coding across multiple neurons in the cortex remains to this date a challenge. Our current understanding of collective encoding of information and the relevant timescales is still limited. Most results are restricted to disparate timescales, focused on either very fast, e.g., spike-synchrony, or slow timescales, e.g., firing rate. Here, we investigated systematically multineuronal activity patterns evolving on different timescales, spanning the whole range from spike-synchrony to mean firing rate. Using multi-electrode recordings from cat visual cortex, we show that cortical responses can be described as trajectories in a high-dimensional pattern space. Patterns evolve on a continuum of coexisting timescales that strongly relate to the temporal properties of stimuli. Timescales consistent with the time constants of neuronal membranes and fast synaptic transmission (5–20 ms) play a particularly salient role in encoding a large amount of stimulus-related information. Thus, to faithfully encode the properties of visual stimuli the brain engages multiple neurons into activity patterns evolving on multiple timescales. PMID:21346812

  15. Detecting the Community Structure and Activity Patterns of Temporal Networks: A Non-Negative Tensor Factorization Approach

    PubMed Central

    Gauvin, Laetitia; Panisson, André; Cattuto, Ciro

    2014-01-01

    The increasing availability of temporal network data is calling for more research on extracting and characterizing mesoscopic structures in temporal networks and on relating such structure to specific functions or properties of the system. An outstanding challenge is the extension of the results achieved for static networks to time-varying networks, where the topological structure of the system and the temporal activity patterns of its components are intertwined. Here we investigate the use of a latent factor decomposition technique, non-negative tensor factorization, to extract the community-activity structure of temporal networks. The method is intrinsically temporal and allows to simultaneously identify communities and to track their activity over time. We represent the time-varying adjacency matrix of a temporal network as a three-way tensor and approximate this tensor as a sum of terms that can be interpreted as communities of nodes with an associated activity time series. We summarize known computational techniques for tensor decomposition and discuss some quality metrics that can be used to tune the complexity of the factorized representation. We subsequently apply tensor factorization to a temporal network for which a ground truth is available for both the community structure and the temporal activity patterns. The data we use describe the social interactions of students in a school, the associations between students and school classes, and the spatio-temporal trajectories of students over time. We show that non-negative tensor factorization is capable of recovering the class structure with high accuracy. In particular, the extracted tensor components can be validated either as known school classes, or in terms of correlated activity patterns, i.e., of spatial and temporal coincidences that are determined by the known school activity schedule. PMID:24497935

  16. A review on the temporal pattern of deer-vehicle accidents: impact of seasonal, diurnal and lunar effects in cervids.

    PubMed

    Steiner, Wolfgang; Leisch, Friedrich; Hackländer, Klaus

    2014-05-01

    The increasing number of deer-vehicle-accidents (DVAs) and the resulting economic costs have promoted numerous studies on behavioural and environmental factors which may contribute to the quantity, spatiotemporal distribution and characteristics of DVAs. Contrary to the spatial pattern of DVAs, data of their temporal pattern is scarce and difficult to obtain because of insufficient accuracy in available datasets, missing standardization in data aquisition, legal terms and low reporting rates to authorities. Literature of deer-traffic collisions on roads and railways is reviewed to examine current understanding of DVA temporal trends. Seasonal, diurnal and lunar peak accident periods are identified for deer, although seasonal pattern are not consistent among and within species or regions and data on effects of lunar cycles on DVAs is almost non-existent. Cluster analysis of seasonal DVA data shows nine distinct clusters of different seasonal DVA pattern for cervid species within the reviewed literature. Studies analyzing the relationship between time-related traffic predictors and DVAs yield mixed results. Despite the seasonal dissimilarity, diurnal DVA pattern are comparatively constant in deer, resulting in pronounced DVA peaks during the hours of dusk and dawn frequently described as bimodal crepuscular pattern. Behavioural aspects in activity seem to have the highest impact in DVAs temporal trends. Differences and variations are related to habitat-, climatic- and traffic characteristics as well as effects of predation, hunting and disturbance. Knowledge of detailed temporal DVA pattern is essential for prevention management as well as for the application and evaluation of mitigation measures. PMID:24549035

  17. The use of census migration data to approximate human movement patterns across temporal scales.

    PubMed

    Wesolowski, Amy; Buckee, Caroline O; Pindolia, Deepa K; Eagle, Nathan; Smith, David L; Garcia, Andres J; Tatem, Andrew J

    2013-01-01

    Human movement plays a key role in economies and development, the delivery of services, and the spread of infectious diseases. However, it remains poorly quantified partly because reliable data are often lacking, particularly for low-income countries. The most widely available are migration data from human population censuses, which provide valuable information on relatively long timescale relocations across countries, but do not capture the shorter-scale patterns, trips less than a year, that make up the bulk of human movement. Census-derived migration data may provide valuable proxies for shorter-term movements however, as substantial migration between regions can be indicative of well connected places exhibiting high levels of movement at finer time scales, but this has never been examined in detail. Here, an extensive mobile phone usage data set for Kenya was processed to extract movements between counties in 2009 on weekly, monthly, and annual time scales and compared to data on change in residence from the national census conducted during the same time period. We find that the relative ordering across Kenyan counties for incoming, outgoing and between-county movements shows strong correlations. Moreover, the distributions of trip durations from both sources of data are similar, and a spatial interaction model fit to the data reveals the relationships of different parameters over a range of movement time scales. Significant relationships between census migration data and fine temporal scale movement patterns exist, and results suggest that census data can be used to approximate certain features of movement patterns across multiple temporal scales, extending the utility of census-derived migration data. PMID:23326367

  18. [Spatial and temporal patterns of stream fish assemblages in the Qiupu Headwaters National Wetland Park].

    PubMed

    Wang, Wen-Jian; Chu, Ling; Si, Chun; Zhu, Ren; Chen, Wen-Hao; Chen, Fang-Ming; Yan, Yun-Zhi

    2013-08-01

    Identifying and clarifying how stream fish assemblage patterns vary spatially and temporally are basic measures for the conservation and management of fish species. Based on data collected from 24 wadeable reaches within the Qiupu Headwaters National Wetland Park between May and October 2012, we examined the spatial and temporal patterns of the assemblage structures and diversities, collecting a total of 29 fish species belonging to four orders and ten families. The results of our survey showed influences of local habitat and tributary spatial position variables on fish assemblages. Fish diversity showed significant variations across stream-orders and seasons, which were higher in the second-order streams than in first-order streams and higher in October than in May. Habitat factors such as substrate coarseness and heterogeneity, water temperature and water depth, as well as tributary position factor-link, showed significant effects on fish diversity. Fish assemblages fitted the nested pattern that upstream assemblages presented as a nested subset of downstream assemblages. Fish assemblage structures did not vary significantly across seasons but did across stream-orders; fish assemblages between first- and second-order streams showed significant differences despite some overlap. These spatial differences mainly resulted from spatial variations of the relative abundance of Cobitis rarus, Ctenogobius sp., Zacco platypus, Phoxinus oxycephalus, Rhodeus ocellatus and Vanmanenia stenosoma, among which P. oxycephalus had higher abundance in first-order than in second-order streams but the other five species were more abundant in second-order streams. Fish assemblage structures were significantly related to substrate heterogeneity, water depth, stream order, link and C-link. PMID:23913894

  19. Temporal patterns and behavioral characteristics of aggregation formation and spawning in the Bermuda chub ( Kyphosus sectatrix)

    NASA Astrophysics Data System (ADS)

    Nemeth, Richard S.; Kadison, Elizabeth

    2013-12-01

    Reef fish spawning aggregations are important life history events that occur at specific times and locations and represent the primary mode of reproduction for many species. This paper provides detailed descriptions of aggregation formation and mass spawning of the Bermuda chub ( Kyphosus sectatrix). Spawning coloration and gamete release of K. sectatrix were observed and filmed at the Grammanik Bank, a deep spawning aggregation site used by many different species located on the southern edge of the Puerto Rican shelf 10 km south of St. Thomas, US Virgin Islands. Underwater visual surveys using technical Nitrox and closed circuit re-breathers were conducted from December 2002 to March 2013 and documented spatial and temporal patterns of movement and aggregation formation along 1.5 km of mesophotic reef. The largest aggregations of K. sectatrix (>200 fish) were observed on the Grammanik Bank January to March from 0 to 11 d after the full moon with peak abundance from 60 to 80 d after the winter solstice across all survey years. Aggregation formation of K. sectatrix coincided with the spawning season of Nassau ( Epinephelus striatus) and yellowfin ( Mycteroperca venenosa) groupers. These spatial and temporal patterns of aggregation formation and spawning suggest that K. sectatrix, an herbivore, may also be a transient aggregating species. On several occasions, chubs were observed both pair spawning and mass spawning. Color patterns and behaviors associated with aggregation and spawning are described and compared to spawning characteristics observed in other species, many of which are similar but others that appear unique to K. sectatrix. This represents the first report of a kyphosid species aggregating to spawn and illuminates a portion of the poorly understood life history of the Bermuda chub.

  20. Spatial and temporal exposure patterns in non-target small mammals during brodifacoum rat control.

    PubMed

    Geduhn, Anke; Esther, Alexandra; Schenke, Detlef; Mattes, Hermann; Jacob, Jens

    2014-10-15

    Worldwide pest rodents on livestock farms are often regulated using anticoagulant rodenticides (ARs). Second generation ARs in particular can cause poisoning in non-target species due to their high toxicity and persistence. However, research on exposure of small mammals is rare. We systematically investigated spatial and temporal exposure patterns of non-target small mammals in a large-scale replicated study. Small mammals were trapped at different distances to bait stations on ten farms before, during and after brodifacoum (BR) bait application, and liver samples of 1178 non-target small mammals were analyzed for residues of eight ARs using liquid chromatography coupled with tandem mass spectrometry. BR residues were present in 23% out of 742 samples collected during and after baiting. We found clear spatial and temporal exposure patterns. High BR residue concentrations mainly occurred within 15m from bait stations. Occurrence and concentrations of residues significantly decreased with increasing distance. This pattern was found in almost all investigated taxa. After baiting, significantly more individuals contained residues than during baiting but concentrations were considerably lower. Residue occurrence and concentrations differed significantly among taxa, with the highest maximal residue concentrations in Apodemus species, which are protected in Germany. Although Sorex species are known to be insectivorous we regularly found residues in this genus. Residues of active agents other than brodifacoum were rare in all samples. The confirmation of substantial primary exposure in non-target small mammals close to the baiting area indicates considerable risk of secondary poisoning of predators, a pathway that was possibly underestimated until now. Our results will help to develop risk mitigation strategies to reduce risk for non-target small mammals, as well as their predators, in relation to biocidal AR usage. PMID:25087064

  1. Passive acoustic telemetry reveals highly variable home range and movement patterns among unicornfish within a marine reserve

    Microsoft Academic Search

    A. Marshell; J. McIlwain; K. L. Rhodes

    2011-01-01

    Marine reserves are the primary management tool for Guam’s reef fish fishery. While a build-up of fish biomass has occurred\\u000a inside reserve boundaries, it is unknown whether reserve size matches the scale of movement of target species. Using passive\\u000a acoustic telemetry, we quantified movement patterns and home range size of two heavily exploited unicornfish Naso unicornis and Naso lituratus. Fifteen

  2. Spatial temporal patterns in heterogeneous traffic flow with a variety of driver behavioural characteristics and vehicle parameters

    NASA Astrophysics Data System (ADS)

    Kerner, Boris S.; Klenov, Sergey L.

    2004-09-01

    A microscopic theory of spatial-temporal congested traffic patterns in heterogeneous traffic flow with a variety of driver behavioural characteristics and vehicle parameters is presented. A microscopic model for heterogeneous traffic flow is developed based on three-phase traffic theory. Diverse congested pattern features at a freeway bottleneck due to an on-ramp in heterogeneous traffic flow on a two-lane freeway are found. A numerical study of these specific pattern features and their comparison with empirical results are performed. A comparison of congested patterns in heterogeneous traffic flow with congested patterns in traffic flow with identical vehicles is made.

  3. Benefiting from a migratory prey: spatio-temporal patterns in allochthonous subsidization of an Arctic predator.

    PubMed

    Giroux, Marie-Andrée; Berteaux, Dominique; Lecomte, Nicolas; Gauthier, Gilles; Szor, Guillaume; Bêty, Joël

    2012-05-01

    1.?Flows of nutrients and energy across ecosystem boundaries have the potential to subsidize consumer populations and modify the dynamics of food webs, but how spatio-temporal variations in autochthonous and allochthonous resources affect consumers' subsidization remains largely unexplored. 2.?We studied spatio-temporal patterns in the allochthonous subsidization of a predator living in a relatively simple ecosystem. We worked on Bylot Island (Nunavut, Canada), where arctic foxes (Vulpes lagopus L.) feed preferentially on lemmings (Lemmus trimucronatus and Dicrostonyx groenlandicus Traill), and alternatively on colonial greater snow geese (Anser caerulescens atlanticus L.). Geese migrate annually from their wintering grounds (where they feed on farmlands and marshes) to the Canadian Arctic, thus generating a strong flow of nutrients and energy across ecosystem boundaries. 3.?We examined the influence of spatial variations in availability of geese on the diet of fox cubs (2003-2005) and on fox reproductive output (1996-2005) during different phases of the lemming cycle. 4.?Using stable isotope analysis and a simple statistical routine developed to analyse the outputs of a multisource mixing model (SIAR), we showed that the contribution of geese to the diet of arctic fox cubs decreased with distance from the goose colony. 5.?The probability that a den was used for reproduction by foxes decreased with distance from the subsidized goose colony and increased with lemming abundance. When lemmings were highly abundant, the effect of distance from the colony disappeared. The goose colony thus generated a spatial patterning of reproduction probability of foxes, while the lemming cycle generated a strong temporal variation of reproduction probability of foxes. 6.?This study shows how the input of energy owing to the large-scale migration of prey affects the functional and reproductive responses of an opportunistic consumer, and how this input is spatially and temporally modulated through the foraging behaviour of the consumer. Thus, perspectives of both landscape and foraging ecology are needed to fully resolve the effects of subsidies on animal demographic processes and population dynamics. PMID:22268371

  4. Behavioral and physiological correlates of temporal pitch perception in electric and acoustic hearing

    PubMed Central

    Carlyon, Robert P.; Mahendran, Suresh; Deeks, John M.; Long, Christopher J.; Axon, Patrick; Baguley, David; Bleeck, Stefan; Winter, Ian M.

    2008-01-01

    In the “4-6” condition of experiment 1, normal-hearing (NH) listeners compared the pitch of a bandpass-filtered pulse train, whose inter-pulse intervals (IPIs) alternated between 4 and 6 ms, to that of isochronous pulse trains. Consistent with previous results obtained at a lower signal level, the pitch of the 4-6 stimulus corresponded to that of an isochronous pulse train having a period of 5.7 ms – longer than the mean IPI of 5 ms. In other conditions the IPI alternated between 3.5-5.5 ms and 4.5-6.5 ms. Experiment 2 was similar but presented electric pulse trains to one channel of a CI. In both cases, as overall IPI increased, the pitch of the alternating-interval stimulus approached that of an isochronous train having a period equal to the mean IPI. Experiment 3 measured compound action potentials (CAPs) to alternating-interval stimuli in guinea pigs and in NH listeners. The CAPs to pulses occurring after 4-ms intervals were smaller than responses to pulses occurring after 6-ms intervals, resulting in a modulated pattern that was independent of overall level. The results are compared to the predictions of a simple model incorporating auditory-nerve (AN) refractoriness, and where pitch is estimated from 1st-order intervals in the AN response. PMID:18247900

  5. [Spatial and temporal patterns of primary and secondary syphilis in Shenzhen, China.

    PubMed

    Hu, Yu-Feng; Sun, Zhen-Qiu; Hong, Fu-Chang; Lan, Li-Na; Pan, Peng; Mo, Yan-Shi; Cai, Yu-Mao; Wen, Li-Zhang; Feng, Tie-Jian

    2010-08-01

    OBJECTIVE: To learn the spatial and temporal patterns of primary syphilis and secondary syphilis in Shenzhen and to provide evidence for carrying out further research on syphilis. METHODS: Primary syphilis and secondary syphilis cases among residents in Shenzhen between 2005 and 2009 (n = 11 303) were geocoded at street office level (n = 55) based on residence at the time of diagnosis. Both spatial and space-time scan statistics were used to identify clusters of street office by using SaTScan software. RESULTS: In the purely spatial analyses, clusters were seen in the junction of the Baoan district and Nanshan district (Xinan, Xixiang, Nanshan and Nantou street office) and in the region near Hong Kong (Dongmen, Shekou, and Futian street office), as well as in the other streets where entertainment industry was relatively developed (Longhua, Huafu, Huangbei and Cuizu street office). The clusters had not changed much in the first four years, but nine clusters appeared in 2009. Annually, the most likely clusters were located in Longhua (2005, P ? 0.001, RR = 3.34), Bamboo (2006, P ? 0.001, RR = 9.59), Huafu (2007, 2008 years, P ? 0.001, RR values were 4.18 and 4.75) and Cuizu (2009, P ? 0.001, RR = 8.02). In the space-time scan analysis, we found 16 significant clusters, which were similar to the pure spatial analyses. However, regional difference were also found, with the most likely cluster was the Guiyuan street office in 2006. CONCLUSION: Spatial and space-time scan statistics seemed to be effective ways in describing the circular disease clusters. We have had a better understanding on spatial and temporal patterns of primary syphilis and secondary syphilis in Shenzhen through spatial and space-time scan statistics of syphilis surveillance data in the recent years. The changes of spatial and temporal patterns of primary syphilis and secondary syphilis were also described by SaTScan software, which also provided useful reference for the preventive strategies on sexually transmitted diseases as well as on HIV. Useful information was also provided for financial investment and cost-effective studies. PMID:21162987

  6. The spatial and temporal distributions of arthropods in forest canopies: uniting disparate patterns with hypotheses for specialisation.

    PubMed

    Wardhaugh, Carl W

    2014-11-01

    Arguably the majority of species on Earth utilise tropical rainforest canopies, and much progress has been made in describing arboreal assemblages, especially for arthropods. The most commonly described patterns for tropical rainforest insect communities are host specificity, spatial specialisation (predominantly vertical stratification), and temporal changes in abundance (seasonality and circadian rhythms). Here I review the recurrent results with respect to each of these patterns and discuss the evolutionary selective forces that have generated them in an attempt to unite these patterns in a holistic evolutionary framework. I propose that species can be quantified along a generalist-specialist scale not only with respect to host specificity, but also other spatial and temporal distribution patterns, where specialisation is a function of the extent of activity across space and time for particular species. When all of these distribution patterns are viewed through the paradigm of specialisation, hypotheses that have been proposed to explain the evolution of host specificity can also be applied to explain the generation and maintenance of other spatial and temporal distribution patterns. The main driver for most spatial and temporal distribution patterns is resource availability. Generally, the distribution of insects follows that of the resources they exploit, which are spatially stratified and vary temporally in availability. Physiological adaptations are primarily important for host specificity, where nutritional and chemical variation among host plants in particular, but also certain prey species and fungi, influence host range. Physiological tolerances of abiotic conditions are also important for explaining the spatial and temporal distributions of some insect species, especially in drier forest environments where desiccation is an ever-present threat. However, it is likely that for most species in moist tropical rainforests, abiotic conditions are valuable indicators of resource availability, rather than physiologically limiting factors. Overall, each distribution pattern is influenced by the same evolutionary forces, but at differing intensities. Consequently, each pattern is linked and not mutually exclusive of the other distribution patterns. Most studies have examined each of these patterns in isolation. Future work should focus on examining the evolutionary drivers of these patterns in concert. Only then can the relative strength of resource availability and distribution, host defensive phenotypes, and biotic and abiotic interactions on insect distribution patterns be determined. PMID:24581118

  7. Monitoring, analyzing and simulating of spatial-temporal changes of landscape pattern over mining area

    NASA Astrophysics Data System (ADS)

    Liu, Pei; Han, Ruimei; Wang, Shuangting

    2014-11-01

    According to the merits of remotely sensed data in depicting regional land cover and Land changes, multi- objective information processing is employed to remote sensing images to analyze and simulate land cover in mining areas. In this paper, multi-temporal remotely sensed data were selected to monitor the pattern, distri- bution and trend of LUCC and predict its impacts on ecological environment and human settlement in mining area. The monitor, analysis and simulation of LUCC in this coal mining areas are divided into five steps. The are information integration of optical and SAR data, LULC types extraction with SVM classifier, LULC trends simulation with CA Markov model, landscape temporal changes monitoring and analysis with confusion matrixes and landscape indices. The results demonstrate that the improved data fusion algorithm could make full use of information extracted from optical and SAR data; SVM classifier has an efficient and stable ability to obtain land cover maps, which could provide a good basis for both land cover change analysis and trend simulation; CA Markov model is able to predict LULC trends with good performance, and it is an effective way to integrate remotely sensed data with spatial-temporal model for analysis of land use / cover change and corresponding environmental impacts in mining area. Confusion matrixes are combined with landscape indices to evaluation and analysis show that, there was a sustained downward trend in agricultural land and bare land, but a continues growth trend tendency in water body, forest and other lands, and building area showing a wave like change, first increased and then decreased; mining landscape has undergone a from small to large and large to small process of fragmentation, agricultural land is the strongest influenced landscape type in this area, and human activities are the primary cause, so the problem should be pay more attentions by government and other organizations.

  8. Precision phenotyping of biomass accumulation in triticale reveals temporal genetic patterns of regulation

    PubMed Central

    Busemeyer, Lucas; Ruckelshausen, Arno; Möller, Kim; Melchinger, Albrecht E.; Alheit, Katharina V.; Maurer, Hans Peter; Hahn, Volker; Weissmann, Elmar A.; Reif, Jochen C.; Würschum, Tobias

    2013-01-01

    To extend agricultural productivity by knowledge-based breeding and tailor varieties adapted to specific environmental conditions, it is imperative to improve our ability to assess the dynamic changes of the phenome of crops under field conditions. To this end, we have developed a precision phenotyping platform that combines various sensors for a non-invasive, high-throughput and high-dimensional phenotyping of small grain cereals. This platform yielded high prediction accuracies and heritabilities for biomass of triticale. Genetic variation for biomass accumulation was dissected with 647 doubled haploid lines derived from four families. Employing a genome-wide association mapping approach, two major quantitative trait loci (QTL) for biomass were identified and the genetic architecture of biomass accumulation was found to be characterized by dynamic temporal patterns. Our findings highlight the potential of precision phenotyping to assess the dynamic genetics of complex traits, especially those not amenable to traditional phenotyping. PMID:23942574

  9. Differentiation of bacterial colonies and temporal growth patterns using hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Mehrübeoglu, Mehrube; Buck, Gregory W.; Livingston, Daniel W.

    2014-09-01

    Detection and identification of bacteria are important for health and safety. Hyperspectral imaging offers the potential to capture unique spectral patterns and spatial information from bacteria which can then be used to detect and differentiate bacterial species. Here, hyperspectral imaging has been used to characterize different bacterial colonies and investigate their growth over time. Six bacterial species (Pseudomonas fluorescens, Escherichia coli, Serratia marcescens, Salmonella enterica, Staphylococcus aureus, Enterobacter aerogenes) were grown on tryptic soy agar plates. Hyperspectral data were acquired immediately after, 24 hours after, and 96 hours after incubation. Spectral signatures from bacterial colonies demonstrated repeatable measurements for five out of six species. Spatial variations as well as changes in spectral signatures were observed across temporal measurements within and among species at multiple wavelengths due to strengthening or weakening reflectance signals from growing bacterial colonies based on their pigmentation. Between-class differences and within-class similarities were the most prominent in hyperspectral data collected 96 hours after incubation.

  10. A method for analyzing temporal patterns of variability of a time series from Poincaré plots

    PubMed Central

    Fishman, Mikkel; Jacono, Frank J.; Park, Soojin; Jamasebi, Reza; Thungtong, Anurak; Loparo, Kenneth A.

    2012-01-01

    The Poincaré plot is a popular two-dimensional, time series analysis tool because of its intuitive display of dynamic system behavior. Poincaré plots have been used to visualize heart rate and respiratory pattern variabilities. However, conventional quantitative analysis relies primarily on statistical measurements of the cumulative distribution of points, making it difficult to interpret irregular or complex plots. Moreover, the plots are constructed to reflect highly correlated regions of the time series, reducing the amount of nonlinear information that is presented and thereby hiding potentially relevant features. We propose temporal Poincaré variability (TPV), a novel analysis methodology that uses standard techniques to quantify the temporal distribution of points and to detect nonlinear sources responsible for physiological variability. In addition, the analysis is applied across multiple time delays, yielding a richer insight into system dynamics than the traditional circle return plot. The method is applied to data sets of R-R intervals and to synthetic point process data extracted from the Lorenz time series. The results demonstrate that TPV complements the traditional analysis and can be applied more generally, including Poincaré plots with multiple clusters, and more consistently than the conventional measures and can address questions regarding potential structure underlying the variability of a data set. PMID:22556398

  11. Temporal patterns in count-to-ten fetal movement charts and their associations with pregnancy characteristics: a prospective cohort study

    PubMed Central

    2012-01-01

    Background Fetal movement counting has long been suggested as a screening tool to identify impaired placental function. However, quantitative limits for decreased fetal movement perform poorly for screening purposes, indicating the need for methodological refinement. We aimed to identify the main individual temporal patterns in fetal movement counting charts, and explore their associations with pregnancy characteristics. Methods In a population-based prospective cohort in Norway, 2009–2011, women with singleton pregnancies counted fetal movements daily from pregnancy week 24 until delivery using a modified "count-to-ten” procedure. To account for intra-woman correlation of observations, we used functional data analysis and corresponding functional principal component analysis to identify the main individual temporal patterns in fetal movement count data. The temporal patterns are described by continuous functional principal component (FPC) curves, with an individual score on each FPC for each woman. These scores were later used as outcome variables in multivariable linear regression analyses, with pregnancy characteristics as explanatory variables. Results Fetal movement charts from 1086 pregnancies were included. Three FPC curves explained almost 99% of the variation in the temporal data, with the first FPC, representing the individual overall counting time, accounting for 91% alone. There were several statistically significant associations between the FPCs and various pregnancy characteristics. However, the effects were small and of limited clinical value. Conclusions This statistical approach for analyzing fetal movement counting data successfully captured clinically meaningful individual temporal patterns and how these patterns vary between women. Maternal body mass index, gestational age and placental site explained little of the variation in the temporal fetal movement counting patterns. Thus, a perceived decrease in fetal movement should not be attributed to a woman’s basic pregnancy characteristics, but assessed as a potential marker of risk. PMID:23126608

  12. Buoyancy characteristics of the bloater (Coregonus hoyi) in relation to patterns of vertical migration and acoustic backscattering

    USGS Publications Warehouse

    Fleischer, Guy W.; TeWinkel, Leslie M.

    1998-01-01

    Acoustic studies in Lake Michigan found that bloaters (Coregonus hoyi) were less reflective per size than the other major pelagic species. This difference in in situ acoustic backscattering could indicate that the deep-water bloaters have compressed swimbladders for much of their vertical range with related implications on buoyancy. To test this hypothesis, the buoyancy characteristics of bloaters were determined with fish placed in a cage that was lowered to bottom and monitored with an underwater camera. We found bloaters were positively buoyant near surface, neutrally buoyant at intermediate strata, and negatively buoyant near bottom. This pattern was consistent for the range of depths bloaters occur. The depth of neutral buoyancy (near the 50-n strata) corresponds with the maximum extent of vertical migration for bloaters observed in acoustic surveys. Fish below this depth would be negatively buoyant which supports our contention that bloaters deeper in the water column have compressed swimbladders. Understanding the buoyancy characteristics of pelagic fishes will help to predict the effects of vertical migration on target strength measurement and confirms the use of acoustics as a tool to identify and quantify the ecological phenomenon of vertical migration.

  13. Temporal variability in winter travel patterns of Yellowstone bison: the effects of road grooming.

    PubMed

    Bruggeman, Jason E; Garrott, Robert A; Bjornlie, Daniel D; White, P J; Watson, Fred G R; Borkowski, John

    2006-08-01

    The influence of winter recreation on wildlife in Yellowstone National Park (YNP), Wyoming and Montana, USA, is a controversial issue. In particular, the effects of road grooming, done to facilitate snowmobile and snowcoach travel, on bison (Bison bison) ecology are under debate. We collected data during winters, from 1997 to 2005, on bison road use, off-road travel, and activity budgets to quantify temporal trends in the amount of bison road and off-road travel and to identify the ecological factors affecting bison movements and use of the groomed road system in the Madison-Gibbon-Firehole (MGF) area of YNP. Using model comparison techniques, we found bison travel patterns to be influenced by multiple, interacting effects. Road travel was negatively correlated with road grooming, and we found no evidence that bison preferentially used groomed roads during winter. Snow water equivalent, bison density, and the springtime melt period were positively correlated with both bison road and off-road travel. From behavioral scans on 68,791 bison, we found that travel is only a small percentage (11%) of all bison activity, with foraging comprising 67% of observations. Also, only 7% of traveling bison and 30% of foraging bison were displacing snow, and we suggest foraging, rather than traveling, is likely the major energetic cost to bison in winter. Bison utilize their own trail network, connecting foraging areas using stream corridors, geothermal pathways, and self-groomed travel routes. Our results indicate that temporal patterns in bison road travel are a manifestation of general travel behavior and that groomed roads in the MGF do not appear to be a major factor influencing bison ecology and spatial redistribution. We suggest that the changes in bison spatial dynamics during the past three decades have likely been the result of the natural phenomenon of density-dependent range expansion, rather than having been caused by the anthropogenic influence of road grooming. PMID:16937817

  14. Rapid Generation of Multiplexed Cell Cocultures Using Acoustic Droplet Ejection Followed by Aqueous Two-Phase Exclusion Patterning

    PubMed Central

    Fang, Yu; Frampton, John P.; Raghavan, Shreya; Sabahi-Kaviani, Rahman; Luker, Gary

    2012-01-01

    The development of tools for patterning cocultures of cells is a fundamental interest among cell biologists and tissue engineers. Although a variety of systems exist for micropatterning cells, the methods used to generate cell micropatterns are often cumbersome and difficult to adapt for tissue engineering purposes. This study combines acoustic droplet ejection and aqueous two-phase system exclusion patterning to introduce a method for patterning cocultures of cells in multiplexed arrays. This new method uses focused acoustic radiation pressure to eject discrete droplets of uniform size from the surface of a dextran solution containing cells. The size of droplets is controlled by adjusting ultrasound parameters, such as pulse, duration, and amplitude. The ejected dextran droplets are captured on a cell culture substrate that is manipulated by a computer-controlled 3D positioning system according to predesigned patterns. Polyethylene glycol solution containing an additional cell type is then added to the culture dish to produce a two-phase system capable of depositing different types of cells around the initial pattern of cells. We demonstrate that our method can produce patterns of islands or lines with two or more cell types. Further, we demonstrate that patterns can be multiplexed for studies involving combinations of multiple cell types. This method offers a tool to transfer cell-containing samples in a contact-free, nozzle-less manner, avoiding sample cross-contamination. It can be used to pattern cell cocultures without complicated fabrication of culture substrates. These capabilities were used to examine the response of cancer cells to the presence of a ligand (CXCL12) secreted from surrounding cocultured cells. PMID:22356298

  15. Spatio-temporal pattern formation on spherical surfaces: numerical simulation and application to solid tumour growth.

    PubMed

    Chaplain, M A; Ganesh, M; Graham, I G

    2001-05-01

    In this paper we examine spatio-temporal pattern formation in reaction-diffusion systems on the surface of the unit sphere in 3D. We first generalise the usual linear stability analysis for a two-chemical system to this geometrical context. Noting the limitations of this approach (in terms of rigorous prediction of spatially heterogeneous steady-states) leads us to develop, as an alternative, a novel numerical method which can be applied to systems of any dimension with any reaction kinetics. This numerical method is based on the method of lines with spherical harmonics and uses fast Fourier transforms to expedite the computation of the reaction kinetics. Numerical experiments show that this method efficiently computes the evolution of spatial patterns and yields numerical results which coincide with those predicted by linear stability analysis when the latter is known. Using these tools, we then investigate the r?le that pre-pattern (Turing) theory may play in the growth and development of solid tumours. The theoretical steady-state distributions of two chemicals (one a growth activating factor, the other a growth inhibitory factor) are compared with the experimentally and clinically observed spatial heterogeneity of cancer cells in small, solid spherical tumours such as multicell spheroids and carcinomas. Moreover, we suggest a number of chemicals which are known to be produced by tumour cells (autocrine growth factors), and are also known to interact with one another, as possible growth promoting and growth inhibiting factors respectively. In order to connect more concretely the numerical method to this application, we compute spatially heterogeneous patterns on the surface of a growing spherical tumour, modelled as a moving-boundary problem. The numerical results strongly support the theoretical expectations in this case. Finally in an appendix we give a brief analysis of the numerical method. PMID:11419617

  16. Holographic analysis of near-field acoustic displacement patterns of operating sonar transducer arrays

    NASA Astrophysics Data System (ADS)

    Fein, Howard

    1993-10-01

    Target discrimination and recognition are dependent on the understanding of the dynamic acoustic information processed by a given sonar array. Visualization of the true near-field acoustic energy distribution of an active sonar array would be of great value to the understanding of the effects of structural defects in the array and its interface to the water medium. Knowledge of the projected near-field acoustic energy would also enhance the analysis of returned signals for homing and target recognition. Holographic interferometry has presented itself as a viable and useful method for the realization of this type of information.

  17. Weather seasonality and temporal pattern of live and dead fuel moisture content in Mediterranean shrubland

    NASA Astrophysics Data System (ADS)

    Pellizzaro, G.; Ventura, A.; Arca, B.; Arca, A.; Duce, P.

    2009-04-01

    Wildland fires represent an important disturbance for ecosystems in the Mediterranean Basin. Many factors affect wildland fire occurrence and behaviour (topography, weather, fuel). At level of vegetation, as well as fuel type, the fuel status, and in particular the water fuel status, plays a crucial role in determining the wildland fire danger. Drier fuel, in fact, makes easier fire ignition and propagation. Evergreen sclerophyll shrubland is a prominent feature of Mediterranean areas; in addition, shrub species are an important component of the understorey vegetation that constitutes the surface fuels primarily responsible for the ignition and the spread of wildland fires in Mediterranean forests. In these areas, where climate is characterized by prolonged summer drought, seasonal decrease of fuel moisture can determine severe fire danger when combined with critical meteorological conditions. Therefore, a better understanding of temporal variation of live and dead fuel moisture content and of their relations to weather variables could contribute to improve our knowledge of burning characteristics of maquis species and to identify critical periods of high ignition danger for Mediterranean ecosystems. The main objectives of this work were i) to describe the temporal pattern of live and dead fuel moisture content (FMC) for some Mediterranean shrubs, ii) to evaluate the influence of weather conditions on the variation of these variables and on the length of fire season and iii) to evaluate the applicability of the moisture codes used in meteorological danger indices to estimate the FMC of dead fuel in Mediterranean ecosystems. The study was carried out in North Western Sardinia (Italy). FMC of live and dead fuel was determined periodically during four consecutive years on several Mediterranean shrub species. Relative to live fuel, phenological phases of each species were also observed during sampling period. During the whole period of experimentation, moisture soil content and meteorological variables were recorded. In addition dead fuel moisture was monitored in field on hourly basis using humidity sensors. Regarding live fuel, the influence of weather seasonal variations and vegetative and reproductive cycle on fuel moisture content was analysed. Different behaviours among species were evidenced. Relative to dead fuel (litter, 1h fraction and 10 h fraction) temporal patterns of moisture content determined by field sampling and humidity sensor were compared to the three moisture codes of the Canadian Forest Fire Weather Index System.

  18. Spatial and temporal patterns of large-scale droughts in Europe: model dispersion and performance

    NASA Astrophysics Data System (ADS)

    Tallaksen, Lena M.; Stahl, Kerstin

    2014-05-01

    Droughts are regional events that have a wide range of environmental and socio-economic impacts and thus, it is vital that models correctly simulate drought characteristics in a future climate. In this study we explore the performance of a suite of off-line, global hydrological and land surface models in mapping spatial and temporal patterns of large-scale hydrological droughts. The model ensemble consists of seven global models run with the same simulation setup (developed in a joint effort within the WATCH project). Daily total runoff (sum of fast and slow component) simulated for each grid cell in Europe for the period 1963-2000 constitute the basis for the analysis. Simulated and observed daily (7-day backward-smoothed) runoff series for each grid cell were first transformed into nonparametric anomalies, and a grid cell is considered to be in drought if the runoff is below q20, i.e., the 20% non-exceedance frequency of that day. The mean annual drought area, i.e., the average of the daily total area in drought, is used to characterize the overall dryness of a year. The annual maximum drought cluster area, i.e., the area of the largest cluster of spatially contiguous cells in drought within a year, is chosen as a measure of the severity of a given drought. The total number of drought events is defined as runs of consecutive days in drought over the entire record. Consistent model behavior was found for inter-annual variability in mean drought area, whereas high model dispersion was revealed in the weekly evolution of contiguous area in drought and its annual maximum. Comparison with nearly three hundred catchment-scale streamflow observations showed an overall tendency to overestimate the number of drought events and hence, underestimate drought duration, whereas persistence in drought affected area (weekly mean) was underestimated, noticeable for one group of models. The high model dispersion in temporal and spatial persistence of drought identified implies that care should be taken when analyzing drought characteristics from only one or a limited number of models unless validated specifically for hydrological drought. Citation: Tallaksen, L.M., Stahl, K. (2014) Spatial and temporal patterns of large-scale droughts in Europe: model dispersion and performance. Geophysical Research Letters (accepted), doi: 10.1002/2013GL058573

  19. Spatial and temporal statistical analysis of bycatch data: Patterns of sea turtle bycatch in the North Atlantic

    USGS Publications Warehouse

    Gardner, B.; Sullivan, P.J.; Morreale, S.J.; Epperly, S.P.

    2008-01-01

    Loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtle distributions and movements in offshore waters of the western North Atlantic are not well understood despite continued efforts to monitor, survey, and observe them. Loggerhead and leatherback sea turtles are listed as endangered by the World Conservation Union, and thus anthropogenic mortality of these species, including fishing, is of elevated interest. This study quantifies spatial and temporal patterns of sea turtle bycatch distributions to identify potential processes influencing their locations. A Ripley's K function analysis was employed on the NOAA Fisheries Atlantic Pelagic Longline Observer Program data to determine spatial, temporal, and spatio-temporal patterns of sea turtle bycatch distributions within the pattern of the pelagic fishery distribution. Results indicate that loggerhead and leatherback sea turtle catch distributions change seasonally, with patterns of spatial clustering appearing from July through October. The results from the space-time analysis indicate that sea turtle catch distributions are related on a relatively fine scale (30-200 km and 1-5 days). The use of spatial and temporal point pattern analysis, particularly K function analysis, is a novel way to examine bycatch data and can be used to inform fishing practices such that fishing could still occur while minimizing sea turtle bycatch. ?? 2008 NRC.

  20. Using dynamic Brownian bridge movement modelling to measure temporal patterns of habitat selection.

    PubMed

    Byrne, Michael E; Clint McCoy, J; Hinton, Joseph W; Chamberlain, Michael J; Collier, Bret A

    2014-01-26

    Accurately describing animal space use is vital to understanding how wildlife use habitat. Improvements in GPS technology continue to facilitate collection of telemetry data at high spatial and temporal resolutions. Application of the recently introduced dynamic Brownian bridge movement model (dBBMM) to such data is promising as the method explicitly incorporates the behavioural heterogeneity of a movement path into the estimated utilization distribution (UD). Utilization distributions defining space use are normally estimated for time-scales ranging from weeks to months, obscuring much of the fine-scale information available from high-volume GPS data sets. By accounting for movement heterogeneity, the dBBMM provides a rigorous, behaviourally based estimate of space use between each set of relocations. Focusing on UDs generated between individual sets of locations allows us to quantify fine-scale circadian variation in habitat use. We used the dBBMM to estimate UDs bounding individual time steps for three terrestrial species with different life histories to illustrate how the method can be used to identify fine-scale variations in habitat use. We also demonstrate how dBBMMs can be used to characterize circadian patterns of habitat selection and link fine-scale patterns of habitat use to behaviour. We observed circadian patterns of habitat use that varied seasonally for a white-tailed deer (Odocoileus virginianus) and coyote (Canis latrans). We found seasonal patterns in selection by the white-tailed deer and were able to link use of conifer forests and agricultural fields to behavioural state of the coyote. Additionally, we were able to quantify the date in which a Rio Grande wild turkey (Meleagris gallopavo intermedia) initiated laying as well as when during the day, she was most likely to visit the nest site to deposit eggs. The ability to quantify circadian patterns of habitat use may have important implications for research and management of wildlife. Additionally, the ability to link such patterns to behaviour may aid in the development of mechanistic models of habitat selection. PMID:24460723

  1. Spatio-temporal patterns of soil water storage under dryland agriculture at the watershed scale

    NASA Astrophysics Data System (ADS)

    Ibrahim, Hesham M.; Huggins, David R.

    2011-07-01

    SummarySpatio-temporal patterns of soil water are major determinants of crop yield potential in dryland agriculture and can serve as the basis for delineating precision management zones. Soil water patterns can vary significantly due to differences in seasonal precipitation, soil properties and topographic features. In this study we used empirical orthogonal function (EOF) analysis to characterize the spatial variability of soil water at the Washington State University Cook Agronomy Farm (CAF) near Pullman, WA. During the period 1999-2006, the CAF was divided into three roughly equal blocks (A, B, and C), and soil water at 0.3 m intervals to a depth of 1.5 m measured gravimetrically at approximately one third of the 369 geo-referenced points on the 37-ha watershed. These data were combined with terrain attributes, soil bulk density and apparent soil conductivity (EC a). The first EOF generated from the three blocks explained 73-76% of the soil water variability. Field patterns of soil water based on EOF interpolation varied between wet and dry conditions during spring and fall seasons. Under wet conditions, elevation and wetness index were the dominant factors regulating the spatial patterns of soil water. As soil dries out during summer and fall, soil properties (EC a and bulk density) become more important in explaining the spatial patterns of soil water. The EOFs generated from block B, which represents average topographic and soil properties, provided better estimates of soil water over the entire watershed with larger Nash-Sutcliffe Coefficient of Efficiency (NSCE) values, especially when the first two EOFs were retained. Including more than the first two EOFs did not significantly increase the NSCE of soil water estimate. The EOF interpolation method to estimate soil water variability worked slightly better during spring than during fall, with average NSCE values of 0.23 and 0.20, respectively. The predictable patterns of stored soil water in the spring could serve as the basis for delineating precision management zones as yield potential is largely driven by water availability. The EOF-based method has the advantage of estimating the soil water variability based on soil water data from several measurement times, whereas in regression methods only soil water measurement at a single time are used. The EOF-based method can also be used to estimate soil water at any time other than measurement times, assuming the average soil water of the watershed is known at that time.

  2. Precipitation extremes in the Yangtze River Basin, China: regional frequency and spatial-temporal patterns

    NASA Astrophysics Data System (ADS)

    Chen, Yongqin David; Zhang, Qiang; Xiao, Mingzhong; Singh, Vijay P.; Leung, Yee; Jiang, Luguang

    2014-05-01

    Regional frequency analysis and spatial-temporal patterns of precipitation extremes are investigated based on daily precipitation data covering 1960-2009 using the index-flood L-moments method together with some advanced statistical tests and spatial analysis techniques. The results indicate that: (1) the entire Yangtze River basin can be divided into six homogeneous regions in terms of extreme daily precipitation index. Goodness-of-fit test indicates that Pearson type III (PE3, three parameters), general extreme-value (GEV, three parameters), and general normal (GNO, three parameters) perform well in fitting regional precipitation extremes; (2) the regional growth curves for each homogeneous region with 99 % error bands show that the quantile estimates are reliable enough and can be used when return periods are less than 100 years, and the results indicate that extreme precipitation events are highly probable to occur in regions V and VI, and hence higher risk of floods and droughts; and (3) spatial patterns of annual extreme daily precipitation with return period of 20 years indicate that precipitation amount increases gradually from the upper to the lower Yangtze River basin, showing higher risks of floods and droughts in the middle and lower Yangtze River basin, and this result is in good agreement with those derived from regional growth curves.

  3. Does sex matter? Temporal and spatial patterns of cougar-human conflict in British Columbia.

    PubMed

    Teichman, Kristine J; Cristescu, Bogdan; Nielsen, Scott E

    2013-01-01

    Wildlife-human conflicts occur wherever large carnivores overlap human inhabited areas. Conflict mitigation can be facilitated by understanding long-term dynamics and examining sex-structured conflict patterns. Predicting areas with high probability of conflict helps focus management strategies in order to proactively decrease carnivore mortality. We investigated the importance of cougar (Puma concolor) habitat, human landscape characteristics and the combination of habitat and human features on the temporal and spatial patterns of cougar-human conflicts in British Columbia. Conflicts (n?=?1,727; 1978-2007) involved similar numbers of male and female cougars with conflict rate decreasing over the past decade. Conflicts were concentrated within the southern part of the province with the most conflicts per unit area occurring on Vancouver Island. For both sexes, the most supported spatial models for the most recent (1998-2007) conflicts contained both human and habitat variables. Conflicts were more likely to occur close to roads, at intermediate elevations and far from the northern edge of the cougar distribution range in British Columbia. Male cougar conflicts were more likely to occur in areas of intermediate human density. Unlike cougar conflicts in other regions, cattle density was not a significant predictor of conflict location. With human populations expanding, conflicts are expected to increase. Conservation tools, such as the maps predicting conflict hotspots from this study, can help focus management efforts to decrease carnivore-human conflict. PMID:24040312

  4. Does Sex Matter? Temporal and Spatial Patterns of Cougar-Human Conflict in British Columbia

    PubMed Central

    Teichman, Kristine J.; Cristescu, Bogdan; Nielsen, Scott E.

    2013-01-01

    Wildlife-human conflicts occur wherever large carnivores overlap human inhabited areas. Conflict mitigation can be facilitated by understanding long-term dynamics and examining sex-structured conflict patterns. Predicting areas with high probability of conflict helps focus management strategies in order to proactively decrease carnivore mortality. We investigated the importance of cougar (Puma concolor) habitat, human landscape characteristics and the combination of habitat and human features on the temporal and spatial patterns of cougar-human conflicts in British Columbia. Conflicts (n?=?1,727; 1978–2007) involved similar numbers of male and female cougars with conflict rate decreasing over the past decade. Conflicts were concentrated within the southern part of the province with the most conflicts per unit area occurring on Vancouver Island. For both sexes, the most supported spatial models for the most recent (1998–2007) conflicts contained both human and habitat variables. Conflicts were more likely to occur close to roads, at intermediate elevations and far from the northern edge of the cougar distribution range in British Columbia. Male cougar conflicts were more likely to occur in areas of intermediate human density. Unlike cougar conflicts in other regions, cattle density was not a significant predictor of conflict location. With human populations expanding, conflicts are expected to increase. Conservation tools, such as the maps predicting conflict hotspots from this study, can help focus management efforts to decrease carnivore-human conflict. PMID:24040312

  5. Spatial and Temporal Patterns of Biocide Action against Staphylococcus epidermidis Biofilms? ‡

    PubMed Central

    Davison, William M.; Pitts, Betsey; Stewart, Philip S.

    2010-01-01

    The dynamic antimicrobial action of chlorine, a quaternary ammonium compound, glutaraldehyde, and nisin within biofilm cell clusters of Staphylococcus epidermidis was investigated using time-lapse confocal scanning laser microscopy. The technique allowed for the simultaneous imaging of changes in biofilm structure and disruption of cellular membrane integrity through the loss of an unbound fluorophore loaded into bacterial cells prior to antimicrobial challenge. Each of the four antimicrobial agents produced distinct spatial and temporal patterns of fluorescence loss. The antimicrobial action of chlorine was localized around the periphery of biofilm cell clusters. Chlorine was the only antimicrobial agent that caused any biofilm removal. Treatment with the quaternary ammonium compound caused membrane permeabilization that started at the periphery of cell clusters, then migrated steadily inward. A secondary pattern superimposed on the penetration dynamic suggested a subpopulation of less-susceptible cells. These bacteria lost fluorescence much more slowly than the majority of the population. Nisin caused a rapid and uniform loss of green fluorescence from all parts of the biofilm without any removal of biofilm. Glutaraldehyde caused no biofilm removal and also no loss of membrane integrity. Measurements of biocide penetration and action time at the center of cell clusters yielded 46 min for 10 mg liter?1 chlorine, 21 min for 50 mg liter?1 chlorine, 25 min for the quaternary ammonium compound, and 4 min for nisin. These results underscore the distinction between biofilm removal and killing and reinforce the critical role of biocide reactivity in determining the rate of biofilm penetration. PMID:20457816

  6. Spatial–temporal patterns in heterogeneous traffic flow with a variety of driver behavioural characteristics and vehicle parameters

    Microsoft Academic Search

    Boris S Kerner; Sergey L Klenov

    2004-01-01

    A microscopic theory of spatial–temporal congested traffic patterns in heterogeneous traffic flow with a variety of driver behavioural characteristics and vehicle parameters is presented. A microscopic model for heterogeneous traffic flow is developed based on three-phase traffic theory. Diverse congested pattern features at a freeway bottleneck due to an on-ramp in heterogeneous traffic flow on a two-lane freeway are found.

  7. Spatial temporal patterns in heterogeneous traffic flow with a variety of driver behavioural characteristics and vehicle parameters

    Microsoft Academic Search

    Boris S. Kerner; Sergey L. Klenov

    2004-01-01

    A microscopic theory of spatial-temporal congested traffic patterns in heterogeneous traffic flow with a variety of driver behavioural characteristics and vehicle parameters is presented. A microscopic model for heterogeneous traffic flow is developed based on three-phase traffic theory. Diverse congested pattern features at a freeway bottleneck due to an on-ramp in heterogeneous traffic flow on a two-lane freeway are found.

  8. Spinodal decomposition and the emergence of dissipative transient periodic spatio-temporal patterns in acentrosomal microtubule multitudes of different morphology.

    PubMed

    Buljan, Vlado A; Holsinger, R M Damian; Brown, D; Bohorquez-Florez, J J; Hambly, B D; Delikatny, E J; Ivanova, E P; Banati, R B

    2013-06-01

    We have studied a spontaneous self-organization dynamics in a closed, dissipative (in terms of guansine 5'-triphosphate energy dissipation), reaction-diffusion system of acentrosomal microtubules (those nucleated and organized in the absence of a microtubule-organizing centre) multitude constituted of straight and curved acentrosomal microtubules, in highly crowded conditions, in vitro. Our data give experimental evidence that cross-diffusion in conjunction with excluded volume is the underlying mechanism on basis of which acentrosomal microtubule multitudes of different morphologies (straight and curved) undergo a spatial-temporal demix. Demix is constituted of a bifurcation process, manifested as a slow isothermal spinodal decomposition, and a dissipative process of transient periodic spatio-temporal pattern formation. While spinodal decomposition is an energy independent process, transient periodic spatio-temporal pattern formation is accompanied by energy dissipative process. Accordingly, we have determined that the critical threshold for slow, isothermal spinodal decomposition is 1.0 ± 0.05 mg/ml of microtubule protein concentration. We also found that periodic spacing of transient periodic spatio-temporal patterns was, in the overall, increasing versus time. For illustration, we found that a periodic spacing of the same pattern was 0.375 ± 0.036 mm, at 36 °C, at 155th min, while it was 0.540 ± 0.041 mm at 31 °C, and at 275th min after microtubule assembly started. The lifetime of transient periodic spatio-temporal patterns spans from half an hour to two hours approximately. The emergence of conditions of macroscopic symmetry breaking (that occur due to cross-diffusion in conjunction with excluded volume) may have more general but critical importance in morphological pattern development in complex, dissipative, but open cellular systems. PMID:23822485

  9. Spinodal decomposition and the emergence of dissipative transient periodic spatio-temporal patterns in acentrosomal microtubule multitudes of different morphology

    NASA Astrophysics Data System (ADS)

    Buljan, Vlado A.; Damian Holsinger, R. M.; Brown, D.; Bohorquez-Florez, J. J.; Hambly, B. D.; Delikatny, E. J.; Ivanova, E. P.; Banati, R. B.

    2013-06-01

    We have studied a spontaneous self-organization dynamics in a closed, dissipative (in terms of guansine 5'-triphosphate energy dissipation), reaction-diffusion system of acentrosomal microtubules (those nucleated and organized in the absence of a microtubule-organizing centre) multitude constituted of straight and curved acentrosomal microtubules, in highly crowded conditions, in vitro. Our data give experimental evidence that cross-diffusion in conjunction with excluded volume is the underlying mechanism on basis of which acentrosomal microtubule multitudes of different morphologies (straight and curved) undergo a spatial-temporal demix. Demix is constituted of a bifurcation process, manifested as a slow isothermal spinodal decomposition, and a dissipative process of transient periodic spatio-temporal pattern formation. While spinodal decomposition is an energy independent process, transient periodic spatio-temporal pattern formation is accompanied by energy dissipative process. Accordingly, we have determined that the critical threshold for slow, isothermal spinodal decomposition is 1.0 ± 0.05 mg/ml of microtubule protein concentration. We also found that periodic spacing of transient periodic spatio-temporal patterns was, in the overall, increasing versus time. For illustration, we found that a periodic spacing of the same pattern was 0.375 ± 0.036 mm, at 36 °C, at 155th min, while it was 0.540 ± 0.041 mm at 31 °C, and at 275th min after microtubule assembly started. The lifetime of transient periodic spatio-temporal patterns spans from half an hour to two hours approximately. The emergence of conditions of macroscopic symmetry breaking (that occur due to cross-diffusion in conjunction with excluded volume) may have more general but critical importance in morphological pattern development in complex, dissipative, but open cellular systems.

  10. Understanding flood-induced water chemistry variability extracting temporal patterns with the LDA method

    NASA Astrophysics Data System (ADS)

    Aubert, A. H.; Tavenard, R.; Emonet, R.; De Lavenne, A.; Malinowski, S.; Guyet, T.; Quiniou, R.; Odobez, J.; Merot, P.; Gascuel-odoux, C.

    2013-12-01

    Studying floods has been a major issue in hydrological research for years, both in quantitative and qualitative hydrology. Stream chemistry is a mix of solutes, often used as tracers, as they originate from various sources in the catchment and reach the stream by various flow pathways. Previous studies (for instance (1)) hypothesized that stream chemistry reaction to a rainfall event is not unique but varies seasonally, and according to the yearly meteorological conditions. Identifying a typology of flood temporal chemical patterns is a way to better understand catchment processes at the flood and seasonal time scale. We applied a probabilistic model (Latent Dirichlet Allocation or LDA (2)) mining recurrent sequential patterns from a dataset of floods. A set of 472 floods was automatically extracted from a daily 12-year long record of nitrate, dissolved organic carbon, sulfate and chloride concentrations. Rainfall, discharge, water table depth and temperature are also considered. Data comes from a long-term hydrological observatory (AgrHys, western France) located at Kervidy-Naizin. From each flood, a document has been generated that is made of a set of "hydrological words". Each hydrological word corresponds to a measurement: it is a triplet made of the considered variable, the time at which the measurement is made (relative to the beginning of the flood), and its magnitude (that can be low, medium or high). The documents and the number of pattern to be mined are used as input data to the LDA algorithm. LDA relies on spotting co-occurrences (as an alternative to the more traditional study of correlation) between words that appear within the flood documents. It has two nice properties that are its ability to easily deal with missing data and its additive property that allows a document to be seen as a mixture of several flood patterns. The output of LDA is a set of patterns easily represented in graphics. These patterns correspond to typical reactions to rainfall events. The patterns themselves are carefully studied, as well as their repartition along the year and along the 12 years of the dataset. We would recommend the use of such model to any study based on patterns or signature extraction. It could be well suited to compare different geographical locations and analyzing the resulting different pattern distributions. (1) Aubert, A.H., Gascuel-Odoux, C., Gruau, G., Akkal, N., Faucheux, M., Fauvel, Y., Grimaldi, C., Hamon, Y., Jaffrezic, A., Lecoz Boutnik, M., Molenat, J., Petitjean, P., Ruiz, L., Merot, Ph. (2013), Solute transport dynamics in small, shallow groundwater-dominated agricultural catchments: insights from a high-frequency, multisolute 10 yr-long monitoring study. Hydrol. Earth Syst. Sci., 17(4): 1379-1391. (2) Aubert, A.H., Tavenard, R, Emonet, R., de Lavenne, A., Malinowski, S., Guyet, T., Quiniou, R., Odobez, J.-M., Merot, Ph., Gascuel-Odoux, C., submitted to WRR. Clustering with a probabilistic method newly applied in hydrology: application on flood events from water quality time-series.

  11. DATA-DRIVEN DISCOVERY OF TEMPORAL AND GEOSPATIAL PATTERNS OF DISEASE TRANSMISSION: WEST NILE VIRUS IN MARYLAND

    EPA Science Inventory

    The necessity of rapid response to a developing disease outbreak often precludes systematic investigation of the mechanisms and patterns (temporal and geospatial) of spread. In order to deploy the most rapid response possible, we must exploit existing data to its maximum extent....

  12. Water quality in the Fort Cobb Watershed, USA: Spatial and temporal patterns of dissolved P stream concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved phosphorus (P) has often been identified as the nutrient of concern in lakes, reservoirs and streams especially where there is evidence of eutrophication. The objective of this work is to identify spatial and temporal patterns in dissolved P [soluble reactive P (SRP) and bioavailable P (B...

  13. Sign Spotting using Hierarchical Sequential Patterns with Temporal Intervals Eng-Jon Ong, Oscar Koller, Nicolas Pugeault, Richard Bowden

    E-print Network

    Bowden, Richard

    Sign Spotting using Hierarchical Sequential Patterns with Temporal Intervals Eng-Jon Ong, Oscar Koller, Nicolas Pugeault, Richard Bowden CVSSP, University of Surrey Guildford GU27XH, UK {e.ong of signs. To ad- dress this, Ong et al [8], proposed a method for building SP forests where multiple SPs

  14. Modelling Spatial and Temporal Forest Cover Change Patterns (1973-2020): A Case Study from South Western Ghats (India)

    Microsoft Academic Search

    Amarnath Giriraj; Mohammed Irfan-Ullah; Manchi Sri; Ramachandra Murthy

    2008-01-01

    This study used time series remote sensing data fro m 1973, 1990 and 2004 to assess spatial forest cover change patterns in the Kalakad-Mundanthurai Tiger Reserve (KMTR), South Western Ghats (India). Analysis of forest cover changes and its causes are the most challenging areas of landscape ecology, es pecially due to the absence of temporal ground data and comparable space

  15. Different Phases of Long-Term Memory Require Distinct Temporal Patterns of PKA Activity after Single-Trial Classical Conditioning

    ERIC Educational Resources Information Center

    Michel, Maximilian; Kemenes, Ildiko; Muller, Uli; Kemenes, Gyorgy

    2008-01-01

    The cAMP-dependent protein kinase (PKA) is known to play a critical role in both transcription-independent short-term or intermediate-term memory and transcription-dependent long-term memory (LTM). Although distinct phases of LTM already have been demonstrated in some systems, it is not known whether these phases require distinct temporal patterns…

  16. Latitudinal and temporal patterns in terrestrial ecosystems recorded by the carbon isotopic composition of plant leaf wax aerosols

    Microsoft Academic Search

    M. H. Conte; J. C. Weber

    2010-01-01

    The molecular and isotopic signatures embedded in biogenic aerosols in boundary layer air masses provide a unique approach for the study of the terrestrial biosphere and climate-biosphere interactions on large spatial scales. Here we describe how the carbon isotopic composition of ablated plant leaf waxes in aerosols can be employed to resolve spatial and temporal patterns in carbon isotopic discrimination

  17. Environmental influences on spatial and temporal patterns of body-size variation in California ground squirrels (Spermophilus beecheyi)

    Microsoft Academic Search

    Jessica L. Blois; Robert S. Feranec; Elizabeth A. Hadly

    2008-01-01

    Aim In order to understand how ground squirrels (Spermophilus beecheyi) may respond to future environmental change, we investigated five biotic and environmental factors potentially responsible for explaining body-size variation in this species across California. We examined the concordance of spatial patterns with temporal body-size change since the last glacial maximum (LGM).

  18. Spatial and Temporal Patterns of Diversity and Distribution of the Upper Juruá River Fish Community (Brazilian Amazon)

    Microsoft Academic Search

    Renato A. M. Silvano; Benedito D. do Amaral; Osvaldo T. Oyakawa

    2000-01-01

    We studied spatial and temporal patterns in fish species composition and diversity at the upper Juruá River located in the west Brazilian Amazon. We collected with gillnet 822 fishes belonging to 90 species in the main Juruá River, its tributaries and the floodplain lakes during wet and dry seasons. Fish abundance and species richness were greater in the dry season.

  19. Geographic Patterns and Temporal Trends of trace Metal Deposition using the Lichen Xanthoparmelia in Maricopa County, Arizona, USA

    E-print Network

    Hall, Sharon J.

    Geographic Patterns and Temporal Trends of trace Metal Deposition using the Lichen Xanthoparmelia in Maricopa County, Arizona, USA ABSTRACT The epilithic lichen Xanthoparmelia spp. was used to assess additional lichens collected from the region in 1970-1973, focusing on decreases in Cu and Pb from

  20. Geographic Patterns and Temporal Trends of trace Metal Deposition using the Lichen Xanthoparmelia in Maricopa County, Arizona, USA

    E-print Network

    Hall, Sharon J.

    Geographic Patterns and Temporal Trends of trace Metal Deposition using the Lichen Xanthoparmelia thallus collected for study ABSTRACT The epilithic lichen Xanthoparmelia spp. was used to assess additional lichens collected from the region in 1970-1973, focusing on decreases in Cu and Pb from

  1. Probing on suitability of TRMM data to explain spatio-temporal pattern of severe storms in tropic region

    NASA Astrophysics Data System (ADS)

    Akbari, A.; Othman, F.; Abu Samah, A.

    2011-10-01

    Spatial and temporal pattern of rainfall play an important role in runoff generation. Raingauge density influences the accuracy of spatial pattern and time interval influence the accuracy of temporal pattern of storms. Usually due to practical and financial limitation the perfect distribution is not achievable. Several sources of data are used to define the behavior of rainfall over a watershed. Raingauges station, radar operation and satellite sensor are the main source of rainfall estimation over the space and time. Recording raingauges are the most common source of rainfall data in many countries. However raingauge network has not adequate coverage in many watersheds spatially in developing countries. Therefore other global source of rainfall data may be useful for hydrological analysis such as flood modeling. This research assessed the ability of TRMM rainfall estimates for explain the Spatio-temporal pattern of severe storm over Klang watershed which is a hydrologically well instrumented watershed. It was experienced that TRMM rainfall estimates are 35% less than actual data for the investigated events. Due to coarse temporal resolution of TRMM (3 h) compare to gauge rainfall (15 min), significant uncertainty influences identifying the start and end of storm event and consequently their resultant time to peak of flood hydrograph which is extremely important in flood forecasting systems. Due to coarse pixel size of TRMM data, watershed scale is important issue.

  2. Temporal pattern and effect of sex on lipopolysaccharide-induced stress hormone and cytokine response in pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The temporal pattern and gender effect on immune and stress hormone responses to a lipopolysaccharide (LPS) challenge was assessed using a pig model. Secretion of the proinflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin-1 (IL-1) beta and IL-6 increased (P < 0.05) in a time-depend...

  3. Temporal pattern and effect of sex on lipopolysaccharide-induced stress hormone and cytokine response in pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The temporal pattern and gender effect of immune and stress hormone responses to a lipopolysaccharide (LPS) challenge were assessed using a pig model. Secretion of the pro-inflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6 increased in a time-dependent manner f...

  4. Spatial and temporal patterns of China's cropland during 1990–2000: An analysis based on Landsat TM data

    Microsoft Academic Search

    Jiyuan Liu; Mingliang Liu; Hanqin Tian; Dafang Zhuang; Zengxiang Zhang; Wen Zhang; Xianming Tang; Xiangzheng Deng

    2005-01-01

    There are large discrepancies among estimates of the cropland area in China due to the lack of reliable data. In this study, we used Landsat TM\\/ETM data at a spatial resolution of 30 m to reconstruct spatial and temporal patterns of cropland across China for the time period of 1990–2000. Our estimate has indicated that total cropland area in China

  5. Interpreting the spatio-temporal patterns of sea turtle strandings: Going with the flow

    USGS Publications Warehouse

    Hart, K.M.; Mooreside, P.; Crowder, L.B.

    2006-01-01

    Knowledge of the spatial and temporal distribution of specific mortality sources is crucial for management of species that are vulnerable to human interactions. Beachcast carcasses represent an unknown fraction of at-sea mortalities. While a variety of physical (e.g., water temperature) and biological (e.g., decomposition) factors as well as the distribution of animals and their mortality sources likely affect the probability of carcass stranding, physical oceanography plays a major role in where and when carcasses strand. Here, we evaluate the influence of nearshore physical oceanographic and wind regimes on sea turtle strandings to decipher seasonal trends and make qualitative predictions about stranding patterns along oceanfront beaches. We use results from oceanic drift-bottle experiments to check our predictions and provide an upper limit on stranding proportions. We compare predicted current regimes from a 3D physical oceanographic model to spatial and temporal locations of both sea turtle carcass strandings and drift bottle landfalls. Drift bottle return rates suggest an upper limit for the proportion of sea turtle carcasses that strand (about 20%). In the South Atlantic Bight, seasonal development of along-shelf flow coincides with increased numbers of strandings of both turtles and drift bottles in late spring and early summer. The model also predicts net offshore flow of surface waters during winter - the season with the fewest relative strandings. The drift bottle data provide a reasonable upper bound on how likely carcasses are to reach land from points offshore and bound the general timeframe for stranding post-mortem (< two weeks). Our findings suggest that marine turtle strandings follow a seasonal regime predictable from physical oceanography and mimicked by drift bottle experiments. Managers can use these findings to reevaluate incidental strandings limits and fishery takes for both nearshore and offshore mortality sources. ?? 2005 Elsevier Ltd. All rights reserved.

  6. Spatial and temporal seismicity patterns from dynamic trigger by great earthquakes

    NASA Astrophysics Data System (ADS)

    Johnson, C. W.; Burgmann, R.

    2013-12-01

    Questions remain regarding the dynamic triggering of large earthquakes at global distances and the role of earthquake nucleation times following dynamic stress perturbations on active faults. At distances beyond 2-3 fault lengths, transient stress changes as a result of seismic waves have been shown to trigger microseismicity in regions of geothermal activity, non-volcanic tremor, and small tectonic earthquakes, i.e. M<3, during the passage of seismic waves and subsequent days. Less frequently, immediate triggering of earthquakes ranging from 3 > M < 5 is detected during the passage of the surface wave train, whereas events M>5 are shown to experience no rate increase outside the aftershock zone of large-magnitude events. An exception to this magnitude threshold for dynamically triggered activity is the MW 8.6 2012 east Indian Ocean earthquake that resulted in above-average global seismicity for events >M5.5 in the 6 days following the mainshock (Pollitz et al., 2012 Nature) followed by a 95 day period of global quiescence for M>=6.5 events (Pollitz et al., 2013 submitted to BSSA). The activity observed following the 2012 event is an example of delayed dynamic triggering which suggests that the stress perturbations experienced during the teleseismic surface waves were large enough to advance the earthquake cycle of multiple >M5 events. Conversely, the same stress changes could suppress activity while earthquake rates return to equilibrium. Here we investigate the idea of global 'dynamic shadowing' in order to determine if a spatial and temporal relationship to large-magnitude events exists for periods of reduced global seismicity. We build on the previous work by Parsons and Velasco (2011 Nature Geoscience) who concluded that increases in M>5 seismicity are confined to within 2-3 fault lengths of the rupture and activity returned to background rates within 36 hours following a M>7 event. Using a similar methodology, we explore the suppression of global activity with respect to background earthquake activity following large magnitude events using 30 years of earthquake catalog data obtained from the Advanced National Seismic System. Our goal is to determine if a dynamic shadow effect results in a reduction of seismicity at a distinguishable level below the background seismicity over various temporal and spatial ranges following the largest cataloged earthquakes. We utilize spatial ranges consistent with maximum transient stress changes for different fault mechanisms in order to document the temporal characteristics of seismicity patterns.

  7. The pattern of acoustic emission under fluid initiation of failure: Laboratory modeling

    NASA Astrophysics Data System (ADS)

    Potanina, M. G.; Smirnov, V. B.; Ponomarev, A. V.; Bernard, P.; Lyubushin, A. A.; Shoziyoev, Sh. P.

    2015-03-01

    The results of the laboratory experiment on the initiation of acoustic emission in a loaded specimen by wetting a part of its surface without a material increase in the pore pressure are analyzed. The experiment was conducted on the lever press at the Schmidt Institute of Physics of the Earth, Russian Academy of Sciences (Sobolev and Ponomarev, 2011). Infusion of water into the surface of the specimen initiated the swarm acoustic emission, which, after having migrated to the area with higher stresses, culminated in the formation of a macrofracture. The analysis revealed the regularities in the excitation and relaxation of the acoustic activity in response to different types of initiation: the forced excitation by stepwise increasing the load at the initial stage of the experiment; excitation resulting from fluid diffusion, which can be associated with the reduction in the material strength due to wetting; excitation that reflects the preparation for the emergence of a macrofracture in the area with the highest Coulomb stresses; and spontaneous excitation of swarm activity at the stage of relaxation of the acoustic emission after the formation of a macrofracture. The features revealed in the acoustic time series at the stages of excitation and decay of the emission are qualitatively similar to the trends identified in the variations of seismic parameters during the natural swarms, preparation of the sources of the strong earthquakes, and relaxation of the aftershocks. In particular, the obtained results support the hypothesis of fluid initiation of nonvolcanic seismic swarms.

  8. Acoustic Telemetry Reveals Large-Scale Migration Patterns of Walleye in Lake Huron

    PubMed Central

    Hayden, Todd A.; Holbrook, Christopher M.; Fielder, David G.; Vandergoot, Christopher S.; Bergstedt, Roger A.; Dettmers, John M.; Krueger, Charles C.; Cooke, Steven J.

    2014-01-01

    Fish migration in large freshwater lacustrine systems such as the Laurentian Great Lakes is not well understood. The walleye (Sander vitreus) is an economically and ecologically important native fish species throughout the Great Lakes. In Lake Huron walleye has recently undergone a population expansion as a result of recovery of the primary stock, stemming from changing food web dynamics. During 2011 and 2012, we used acoustic telemetry to document the timing and spatial scale of walleye migration in Lake Huron and Saginaw Bay. Spawning walleye (n?=?199) collected from a tributary of Saginaw Bay were implanted with acoustic tags and their migrations were documented using acoustic receivers (n?=?140) deployed throughout U.S. nearshore waters of Lake Huron. Three migration pathways were described using multistate mark-recapture models. Models were evaluated using the Akaike Information Criterion. Fish sex did not influence migratory behavior but did affect migration rate and walleye were detected on all acoustic receiver lines. Most (95%) tagged fish migrated downstream from the riverine tagging and release location to Saginaw Bay, and 37% of these fish emigrated from Saginaw Bay into Lake Huron. Remarkably, 8% of walleye that emigrated from Saginaw Bay were detected at the acoustic receiver line located farthest from the release location more than 350 km away. Most (64%) walleye returned to the Saginaw River in 2012, presumably for spawning. Our findings reveal that fish from this stock use virtually the entirety of U.S. nearshore waters of Lake Huron. PMID:25506913

  9. Muscle wasting and the temporal gene expression pattern in a novel rat intensive care unit model

    PubMed Central

    2011-01-01

    Background Acute quadriplegic myopathy (AQM) or critical illness myopathy (CIM) is frequently observed in intensive care unit (ICU) patients. To elucidate duration-dependent effects of the ICU intervention on molecular and functional networks that control the muscle wasting and weakness associated with AQM, a gene expression profile was analyzed at time points varying from 6 hours to 14 days in a unique experimental rat model mimicking ICU conditions, i.e., post-synaptically paralyzed, mechanically ventilated and extensively monitored animals. Results During the observation period, 1583 genes were significantly up- or down-regulated by factors of two or greater. A significant temporal gene expression pattern was constructed at short (6 h-4 days), intermediate (5-8 days) and long (9-14 days) durations. A striking early and maintained up-regulation (6 h-14d) of muscle atrogenes (muscle ring-finger 1/tripartite motif-containing 63 and F-box protein 32/atrogin-1) was observed, followed by an up-regulation of the proteolytic systems at intermediate and long durations (5-14d). Oxidative stress response genes and genes that take part in amino acid catabolism, cell cycle arrest, apoptosis, muscle development, and protein synthesis together with myogenic factors were significantly up-regulated from 5 to 14 days. At 9-14 d, genes involved in immune response and the caspase cascade were up-regulated. At 5-14d, genes related to contractile (myosin heavy chain and myosin binding protein C), regulatory (troponin, tropomyosin), developmental, caveolin-3, extracellular matrix, glycolysis/gluconeogenesis, cytoskeleton/sarcomere regulation and mitochondrial proteins were down-regulated. An activation of genes related to muscle growth and new muscle fiber formation (increase of myogenic factors and JunB and down-regulation of myostatin) and up-regulation of genes that code protein synthesis and translation factors were found from 5 to 14 days. Conclusions Novel temporal patterns of gene expression have been uncovered, suggesting a unique, coordinated and highly complex mechanism underlying the muscle wasting associated with AQM in ICU patients and providing new target genes and avenues for intervention studies. PMID:22165895

  10. Spatio-Temporal Migration Patterns of Pacific Salmon Smolts in Rivers and Coastal Marine Waters

    PubMed Central

    Melnychuk, Michael C.; Welch, David W.; Walters, Carl J.

    2010-01-01

    Background Migrations allow animals to find food resources, rearing habitats, or mates, but often impose considerable predation risk. Several behavioural strategies may reduce this risk, including faster travel speed and taking routes with shorter total distance. Descriptions of the natural range of variation in migration strategies among individuals and populations is necessary before the ecological consequences of such variation can be established. Methodology/Principal Findings Movements of tagged juvenile coho, steelhead, sockeye, and Chinook salmon were quantified using a large-scale acoustic tracking array in southern British Columbia, Canada. Smolts from 13 watersheds (49 watershed/species/year combinations) were tagged between 2004–2008 and combined into a mixed-effects model analysis of travel speed. During the downstream migration, steelhead were slower on average than other species, possibly related to freshwater residualization. During the migration through the Strait of Georgia, coho were slower than steelhead and sockeye, likely related to some degree of inshore summer residency. Hatchery-reared smolts were slower than wild smolts during the downstream migration, but after ocean entry, average speeds were similar. In small rivers, downstream travel speed increased with body length, but in the larger Fraser River and during the coastal migration, average speed was independent of body length. Smolts leaving rivers located towards the northern end of the Strait of Georgia ecosystem migrated strictly northwards after ocean entry, but those from rivers towards the southern end displayed split-route migration patterns within populations, with some moving southward. Conclusions/Significance Our results reveal a tremendous diversity of behavioural migration strategies used by juvenile salmon, across species, rearing histories, and habitats, as well as within individual populations. During the downstream migration, factors that had strong effects on travel speeds included species, wild or hatchery-rearing history, watershed size and, in smaller rivers, body length. During the coastal migration, travel speeds were only strongly affected by species differences. PMID:20886121

  11. Very high resolution airborne imagery for characterising spatial and temporal thermal patterns of braided rivers

    NASA Astrophysics Data System (ADS)

    Wawrzyniak, V.; Piégay, H.; Allemand, P.; Grandjean, P.

    2011-12-01

    At the catchment scale water temperature is influenced by geographical factors, but at the reach scale superficial and groundwater hydrology and channel geometry strongly affect thermal patterns. During the last 30 years, studies have been pointed out the significance and complexity of water exchanges between the channel and the hyporheic and phreatic zones. These surface-subsurface water exchanges influence water temperature patterns. Braided rivers present particular thermal conditions with very high spatial water temperature variability. This high thermal variability is difficult to comprehend using only in situ measurements and so thermal infrared (TIR) remote sensing is particularly suited to assessing the thermal patterns associated with these rivers. The aims of this study are to evaluate temperature patterns of nine braided reaches at very high spatial resolution (~20 cm) and to link temperature and water-body types. We hypothesized that river type has an influence of the spatial patterns of water temperature and that the patterns change through the day. All reaches are located in France, in the Rhône catchment. The nine reaches were selected based on high aquatic habitat diversities and are located in three regional areas: the massif des Écrins, the Rhône valley, and south Alps. They are about 1 km long. We have three distinct temporal approaches. The first one is a multi-site approach which proposes one survey of each site during summers 2010 or 2011. Three reaches were selected for the second phase (a multi-annual analysis and were therefore imaged both in summers 2010 and 2011. The last phase is an intra-day survey of two reaches with several flights at different times of day. This presentation focuses on the last approach with two reaches of the Drôme and Drac Noir rivers. To observe the evolution of the thermal patterns of these two reaches through the day, four flights within a day were realized during summer 2011 for both sites. The Drôme reach (44°44' N, 4°56' E) is characterized by a nivo-pluvial regime while the Drac Noir (44°40' N, 6°18' E) is a glacial river. Very high spatial resolution thermal images are needed because braided rivers have multiple, often narrow, channels. Satellite and aircraft TIR do not have fine enough spatial resolutions and consequently we used a drone, a helicopter and a paraglider to acquire sets of images. The three vector types were equipped with a thermal camera (7.5-14 ?m) which can detect noise equivalent temperature differences of ±0.08°C. Based on flight and camera parameter, we collected thermal images with very high spatial resolution (10-30 cm). At the same time as the thermal acquisitions, visible images were recorded and in situ measurements of water temperatures, velocities and discharges were taken.

  12. Multivariate pattern analysis reveals anatomical connectivity differences between the left and right mesial temporal lobe epilepsy.

    PubMed

    Fang, Peng; An, Jie; Zeng, Ling-Li; Shen, Hui; Chen, Fanglin; Wang, Wensheng; Qiu, Shijun; Hu, Dewen

    2015-01-01

    Previous studies have demonstrated differences of clinical signs and functional brain network organizations between the left and right mesial temporal lobe epilepsy (mTLE), but the anatomical connectivity differences underlying functional variance between the left and right mTLE remain uncharacterized. We examined 43 (22 left, 21 right) mTLE patients with hippocampal sclerosis and 39 healthy controls using diffusion tensor imaging. After the whole-brain anatomical networks were constructed for each subject, multivariate pattern analysis was applied to classify the left mTLE from the right mTLE and extract the anatomical connectivity differences between the left and right mTLE patients. The classification results reveal 93.0% accuracy for the left mTLE versus the right mTLE, 93.4% accuracy for the left mTLE versus controls and 90.0% accuracy for the right mTLE versus controls. Compared with the right mTLE, the left mTLE exhibited a different connectivity pattern in the cortical-limbic network and cerebellum. The majority of the most discriminating anatomical connections were located within or across the cortical-limbic network and cerebellum, thereby indicating that these disease-related anatomical network alterations may give rise to a portion of the complex of emotional and memory deficit between the left and right mTLE. Moreover, the orbitofrontal gyrus, cingulate cortex, hippocampus and parahippocampal gyrus, which exhibit high discriminative power in classification, may play critical roles in the pathophysiology of mTLE. The current study demonstrated that anatomical connectivity differences between the left mTLE and the right mTLE may have the potential to serve as a neuroimaging biomarker to guide personalized diagnosis of the left and right mTLE. PMID:25844312

  13. Convective rain cells: radar-derived spatio-temporal characteristics and synoptic patterns

    NASA Astrophysics Data System (ADS)

    Peleg, N.; Morin, E.

    2012-04-01

    In this study we present the spatiotemporal characteristics of convective rain cells over the Eastern Mediterranean (northern Israel) and their relationship to synoptic patterns. Information on rain cell features was extracted from high-resolution weather radar data for a total of 191,586 radar volume scans from 12 hydrological years. The convective rain cell features (i.e., cell area, rainfall intensity and cell orientation) were obtained using cell segmentation technique. Cell tracking algorithm was used to analyze the changes of those features over time. Convective rain cells were clustered into three synoptic types (two extratropical winter lows: deep Cyprus low and shallow low, and a tropical intrusion: Active Red Sea Trough) using several NCEP/NCAR parameters, and empirical distributions were computed for their spatial and temporal features. In the study region, it was found that the Active Red Sea Trough rain cells are larger, live for less time and possess lower rain intensities than the rain cells generated by the winter lows. The Cyprus low rain cells were found to be less intense and slightly larger on average than the shallow low rain cells. It was further discovered that the preferential orientation of the rain cells is associated with the direction and velocity of the wind. The effect of distance from the coastline was also examined. An increase in the number and area of the rain cells near the coastline was observed, presumably due to the sea breeze convection. The mean rainfall intensity was found to peak near the shore and decrease with distance inland. This information is of great importance for understanding rain patterns and can be further applied in exploring the hydrological responses of the basins in this region. The presented study is the first step in achieving the long-term goal: to develop a high space-time resolution weather generator for creating rainfall ensembles under different climatology scenarios. Those rainfall ensembles will be incorporated into hydrological models for simulating hydrological response under predicted climate changes.

  14. Optimized temporally deconvolved Ca²? imaging allows identification of spatiotemporal activity patterns of CA1 hippocampal ensembles.

    PubMed

    Pfeiffer, Thomas; Draguhn, Andreas; Reichinnek, Susanne; Both, Martin

    2014-07-01

    Hippocampal activity is characterized by the coordinated firing of a subset of neurons. Such neuronal ensembles can either be driven by external stimuli to form new memory traces or be reactivated by intrinsic mechanisms to reactivate and consolidate old memories. Hippocampal network oscillations orchestrate this coherent activity. One key question is how the topology, i.e. the functional connectivity of neuronal networks supports their desired function. Recently, this has been addressed by characterizing the intrinsic properties for the highly recurrently connected CA3 region using organotypic slice cultures and Ca(2+) imaging. In the present study, we aimed to determine the properties of CA1 hippocampal ensembles at high temporal and multiple single cell resolution. Thus, we performed Ca(2+) imaging using the chemical fluorescent Ca(2+) indicator Oregon Green BAPTA 1-AM. To achieve most physiological conditions, we used acute hippocampal slices that were recorded in a so-called interface chamber. To faithfully reconstruct firing patterns of multiple neurons in the field of view, we optimized deconvolution-based detection of action potential associated Ca(2+) events. Our approach outperformed currently available detection algorithms by its sensitivity and robustness. In combination with advanced network analysis, we found that acute hippocampal slices contain a median of 11 CA1 neuronal ensembles with a median size of 4 neurons. This apparently low number of neurons is likely due to the confocal imaging acquisition and therefore yields a lower limit. The distribution of ensemble sizes was compatible with a scale-free topology, as far as can be judged from data with small cell numbers. Interestingly, cells were more tightly clustered in large ensembles than in smaller groups. Together, our data show that spatiotemporal activity patterns of hippocampal neuronal ensembles can be reliably detected with deconvolution-based imaging techniques in mouse hippocampal slices. The here presented techniques are fully applicable to similar studies of distributed optical measurements of neuronal activity (in vivo), where signal-to-noise ratio is critical. PMID:24650598

  15. Spatial, temporal, and interspecies patterns in fine particulate matter in Texas

    SciTech Connect

    Kristi A. Gebhart; William C. Malm; Lowell L. Ashbaugh [Colorado State University, Fort Collins, CO (United States). National Park Service

    2005-11-01

    The Big Bend Regional Aerosol and Visibility Observational (BRAVO) field study was conducted from July to October 1999 and was followed by several years of modeling and data analyses to examine the causes of haze at Big Bend National Park TX (BBNP). During BRAVO, daily speciated fine (diameter <2.5 {mu}m) particulate concentrations were measured at 37 sites throughout Texas. At the primary receptor site, K-Bar Ranch, there were many additional measurements including a 'high-sensitivity' version of the 24-hr fine particulate elemental data. The spatial, temporal, and interspecies patterns in these data are examined here to qualitatively investigate source regions and source types influencing the fine particulate concentrations in Texas with an emphasis on sources of sulfates, the largest contributor to fine mass and light extinction. Peak values of particulate sulfur (S) varied spatially and seasonally. Maximum S was in Northeast Texas during the summer, whereas peak S at BBNP was in the fall. Sulfate acidity at BBNP also varied by month. Sources of Se were evident in Northeast Texas and from the Carbon I and II coal-fired plants. High S episodes at BBNP during BRAVO had several different trace element characteristics. Carbon concentrations at BBNP during BRAVO were probably mostly urban-related, with arrival from the Houston area likely. The Houston artificial tracer released during the second half of BRAVO was highly correlated with some carbon fractions. There was evidence of the influence of African dust at sites throughout Texas during the summer. Patterns in several trace elements were also examined. Vanadium was associated with air masses from Mexico. Lead concentrations in southern Texas have dropped dramatically over the past several years. 23 refs., 9 figs., 2 tabs.

  16. Convergence and Divergence in the Evolution of Cat Skulls: Temporal and Spatial Patterns of Morphological Diversity

    PubMed Central

    Sakamoto, Manabu; Ruta, Marcello

    2012-01-01

    Background Studies of biological shape evolution are greatly enhanced when framed in a phylogenetic perspective. Inclusion of fossils amplifies the scope of macroevolutionary research, offers a deep-time perspective on tempo and mode of radiations, and elucidates life-trait changes. We explore the evolution of skull shape in felids (cats) through morphometric analyses of linear variables, phylogenetic comparative methods, and a new cladistic study of saber-toothed cats. Methodology/Principal Findings A new phylogenetic analysis supports the monophyly of saber-toothed cats (Machairodontinae) exclusive of Felinae and some basal felids, but does not support the monophyly of various saber-toothed tribes and genera. We quantified skull shape variation in 34 extant and 18 extinct species using size-adjusted linear variables. These distinguish taxonomic group membership with high accuracy. Patterns of morphospace occupation are consistent with previous analyses, for example, in showing a size gradient along the primary axis of shape variation and a separation between large and small-medium cats. By combining the new phylogeny with a molecular tree of extant Felinae, we built a chronophylomorphospace (a phylogeny superimposed onto a two-dimensional morphospace through time). The evolutionary history of cats was characterized by two major episodes of morphological divergence, one marking the separation between saber-toothed and modern cats, the other marking the split between large and small-medium cats. Conclusions/Significance Ancestors of large cats in the ‘Panthera’ lineage tend to occupy, at a much later stage, morphospace regions previously occupied by saber-toothed cats. The latter radiated out into new morphospace regions peripheral to those of extant large cats. The separation between large and small-medium cats was marked by considerable morphologically divergent trajectories early in feline evolution. A chronophylomorphospace has wider applications in reconstructing temporal transitions across two-dimensional trait spaces, can be used in ecophenotypical and functional diversity studies, and may reveal novel patterns of morphospace occupation. PMID:22792186

  17. Spatio-Temporal Expression Patterns of Arabidopsis thaliana and Medicago truncatula Defensin-Like Genes

    PubMed Central

    Nallu, Sumitha; Wang, Lin; Botanga, Christopher J.; Gomez, S. Karen; Costa, Liliana M.; Harrison, Maria J.; Samac, Deborah A.; Glazebrook, Jane; Katagiri, Fumiaki; Gutierrez-Marcos, Jose F.; VandenBosch, Kathryn A.

    2013-01-01

    Plant genomes contain several hundred defensin-like (DEFL) genes that encode short cysteine-rich proteins resembling defensins, which are well known antimicrobial polypeptides. Little is known about the expression patterns or functions of many DEFLs because most were discovered recently and hence are not well represented on standard microarrays. We designed a custom Affymetrix chip consisting of probe sets for 317 and 684 DEFLs from Arabidopsis thaliana and Medicago truncatula, respectively for cataloging DEFL expression in a variety of plant organs at different developmental stages and during symbiotic and pathogenic associations. The microarray analysis provided evidence for the transcription of 71% and 90% of the DEFLs identified in Arabidopsis and Medicago, respectively, including many of the recently annotated DEFL genes that previously lacked expression information. Both model plants contain a subset of DEFLs specifically expressed in seeds or fruits. A few DEFLs, including some plant defensins, were significantly up-regulated in Arabidopsis leaves inoculated with Alternaria brassicicola or Pseudomonas syringae pathogens. Among these, some were dependent on jasmonic acid signaling or were associated with specific types of immune responses. There were notable differences in DEFL gene expression patterns between Arabidopsis and Medicago, as the majority of Arabidopsis DEFLs were expressed in inflorescences, while only a few exhibited root-enhanced expression. By contrast, Medicago DEFLs were most prominently expressed in nitrogen-fixing root nodules. Thus, our data document salient differences in DEFL temporal and spatial expression between Arabidopsis and Medicago, suggesting distinct signaling routes and distinct roles for these proteins in the two plant species. PMID:23527067

  18. Spatio-temporal pattern of NPP and related analyses with terrain factors in Wuling mountainous area

    NASA Astrophysics Data System (ADS)

    Sun, L. Qing; Xiao, Xiao; Feng, Feng X.

    2014-11-01

    Based on the MODIS NPP data, terrain data, and land cover map, spatio-temporal pattern of NPP in Wuling mountainous area during 2001-2010 and its relationships with the elevation and slope were analyzed using regression analysis and classification statistics. Results showed that the average annual NPP of the study area from 2001 to 2010 was 590.72 g C m-2 yr-1. The mean NPP of forest, shrub/grassland, and cropland were 596.79 g C m-2 yr-1, 586.98 g C m-2 yr-1, and 563.31 g C m-2 yr-1, respectively. During 2001-2010, the average annual total NPP of Wuling mountainous area was 98.90 T g C yr-1, ranging from 92.79 T g C yr-1 to 106.99 T g C yr-1. Besides, the spatial pattern of interannual variability of NPP in the north of our study area presented a significant increase trend while in the south it displayed an opposite tendency. According to the relationships between mean NPP and elevation as well as slope at steps of 30m and 3°, respectively, NPP increased with the altitude and slope first, then decreased slowly, but when the elevation above 1500m or the slope greater than 50°, the mean NPP presented large fluctuations. However, on the whole, mean NPP increased with the altitude and slope first, then decreased again. Additionally, mean NPP within elevation range of 200m-1000m and slope range of 5°-25° were relatively high, but it decreased one after another in the zones above 500m and had a trend of increase when the slope zones greater than 50°, which reflected the erosion intensity was weakened when the slope greater than a certain threshold.

  19. Multivariate pattern analysis reveals anatomical connectivity differences between the left and right mesial temporal lobe epilepsy

    PubMed Central

    Fang, Peng; An, Jie; Zeng, Ling-Li; Shen, Hui; Chen, Fanglin; Wang, Wensheng; Qiu, Shijun; Hu, Dewen

    2015-01-01

    Previous studies have demonstrated differences of clinical signs and functional brain network organizations between the left and right mesial temporal lobe epilepsy (mTLE), but the anatomical connectivity differences underlying functional variance between the left and right mTLE remain uncharacterized. We examined 43 (22 left, 21 right) mTLE patients with hippocampal sclerosis and 39 healthy controls using diffusion tensor imaging. After the whole-brain anatomical networks were constructed for each subject, multivariate pattern analysis was applied to classify the left mTLE from the right mTLE and extract the anatomical connectivity differences between the left and right mTLE patients. The classification results reveal 93.0% accuracy for the left mTLE versus the right mTLE, 93.4% accuracy for the left mTLE versus controls and 90.0% accuracy for the right mTLE versus controls. Compared with the right mTLE, the left mTLE exhibited a different connectivity pattern in the cortical-limbic network and cerebellum. The majority of the most discriminating anatomical connections were located within or across the cortical-limbic network and cerebellum, thereby indicating that these disease-related anatomical network alterations may give rise to a portion of the complex of emotional and memory deficit between the left and right mTLE. Moreover, the orbitofrontal gyrus, cingulate cortex, hippocampus and parahippocampal gyrus, which exhibit high discriminative power in classification, may play critical roles in the pathophysiology of mTLE. The current study demonstrated that anatomical connectivity differences between the left mTLE and the right mTLE may have the potential to serve as a neuroimaging biomarker to guide personalized diagnosis of the left and right mTLE. PMID:25844312

  20. The development of articular cartilage: I. The spatial and temporal patterns of collagen types.

    PubMed Central

    Morrison, E H; Ferguson, M W; Bayliss, M T; Archer, C W

    1996-01-01

    Articular cartilage is both morphologically and biochemically heterogeneous. Its susceptibility to degenerative diseases such as arthritis and its limited repair capacity have made cartilage the focus of intense study; surprisingly, little is known of its development. Using a panel of specific antibodies, we have documented the temporal and spatial patterns of collagen types I, II, III, VI and X in the developing knee cartilage of the marsupial Monodelphis domestica from parturition to adulthood. Type I collagen was initially detected in the presumptive articular cartilage of the epiphyses in addition to the perichondrium. By 14 d postparturition, type I collagen was not detectable in the epiphyseal cartilage apart from insertion sites of ligaments and tendons of the joint. Similarly, type III collagen was detected at insertion sites of the major ligaments and tendons and within the perichondrium/periosteum but was never detected in the cartilage per se. Type II collagen was predictably distributed throughout the cartilage matrix and was also detected in the perichondrium. Type VI collagen was widely distributed throughout the cartilage matrix at parturition, but during development became restricted to a pericellular location particularly towards the presumptive articular cartilage, i.e. the epiphysis. Interestingly, generalised matrix immunopositivity was only retained in the hypertrophic cartilage of the secondary centre of ossification. After the formation of the secondary centre, type VI collagen became localised pericellularly in the deeper regions of the articular cartilage but was absent in the cartilage of the growth plate. Type X collagen showed a novel distribution pattern. In addition to being synthesised by hypertrophic chondrocytes, this collagen type was also expressed transiently by some cells at the presumptive articular surface. Furthermore, these surface chondrocytes also stained histochemically for alkaline phosphatase, suggesting that they were terminally differentiated. The fate of these terminally differentiated cells is unknown. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:8771392

  1. Hierarchical Bayesian modeling of spatio-temporal patterns of lung cancer incidence risk in Georgia, USA: 2000-2007

    NASA Astrophysics Data System (ADS)

    Yin, Ping; Mu, Lan; Madden, Marguerite; Vena, John E.

    2014-10-01

    Lung cancer is the second most commonly diagnosed cancer in both men and women in Georgia, USA. However, the spatio-temporal patterns of lung cancer risk in Georgia have not been fully studied. Hierarchical Bayesian models are used here to explore the spatio-temporal patterns of lung cancer incidence risk by race and gender in Georgia for the period of 2000-2007. With the census tract level as the spatial scale and the 2-year period aggregation as the temporal scale, we compare a total of seven Bayesian spatio-temporal models including two under a separate modeling framework and five under a joint modeling framework. One joint model outperforms others based on the deviance information criterion. Results show that the northwest region of Georgia has consistently high lung cancer incidence risk for all population groups during the study period. In addition, there are inverse relationships between the socioeconomic status and the lung cancer incidence risk among all Georgian population groups, and the relationships in males are stronger than those in females. By mapping more reliable variations in lung cancer incidence risk at a relatively fine spatio-temporal scale for different Georgian population groups, our study aims to better support healthcare performance assessment, etiological hypothesis generation, and health policy making.

  2. Spatial and temporal variability of subsurface flow patterns at the hillslope scale: an experimental analysis

    NASA Astrophysics Data System (ADS)

    Penna, Daniele; Hopp, Luisa; Dalla Fontana, Giancarlo; Borga, Marco

    2014-05-01

    Despite the importance of subsurface flow in regulating catchment runoff and slope stability, the dominant controls on the spatial and temporal variability of subsurface flow patterns on hillslopes of headwater catchments are still poorly understood. In this work, we used groundwater data from spatially distributed piezometric wells on two alpine hillslopes to investigate the main factors controlling the water table response to precipitation. Particularly, we tested the following hypotheses: i) piezometric response triggering is jointly controlled by antecedent moisture condition and rainfall depth; ii) contrasting hillslope topographic features affect the magnitude and dynamics of piezometric response, and iii) soil depth controls the timing of piezometric response. Two steep hillslopes of similar size, soil properties and vegetation cover but contrasting topography (divergent-convex and relatively planar morphology) in the 0.14 km2 Bridge Creek Catchment (Dolomites, Central-Eastern Italian Alps) were instrumented with 24 piezometric wells, ranging in depth between 0.7 m and 1.5 m from the soil surface. The analysis was conducted for 63 rainfall-runoff events selected over three years in the snow-free months. Results show that piezometric response, although very variable both in space and in time, was clearly distinct for events that occurred during wet or dry conditions, distinguished on the basis of a threshold relation between stormflow and an index combining antecedent soil moisture and rainfall depth. Correlation analysis based on two metrics of transient water table response (percentage of well activation and piezometric peak) revealed that antecedent soil water content alone was the poorest predictor of piezometric response whereas the highest degree of variance was explained by the combination of rainfall and antecedent soil moisture. Hillslope topography played a significant role on water table peak only for the site characterized by an overall convex-divergent morphology. As at other experimental sites, groundwater was found to not rise in unison throughout the hillslope, violating the steady-state assumption. However, in contrast with many other studies, we observed that water table level at the top of the hillslope typically peaked earlier and was less variable than at the hillslope toe. We related this behaviour to the control exerted by soil depth that increased in downslope direction. The temporal structure of the piezometric response, mainly driven by the soil depth and hillslope topography, led to consistent hysteretic behaviour, characterized by the highest variability for intermediate groundwater levels and the lowest during wet conditions. On the one hand, this work contributes to improve the comprehension of the hydrological behaviour of the study catchment, adding new information on the effect of topography of individual hillslopes and of soil depth on the spatial and temporal dynamics of subsurface flow patterns. On the other hand, these results offer insights, previously missing, on the main controls governing the water table response in alpine hillslopes, and likely in other hillslopes of humid catchments worldwide, that are generally poorly investigated due to practical difficulties in monitoring groundwater variations. Keywords: water table dynamics; hillslope topography; antecedent conditions; hysteresis; soil depth, steady state.

  3. We'll Meet Again: Revealing Distributional and Temporal Patterns of Social Contact

    PubMed Central

    Pachur, Thorsten; Schooler, Lael J.; Stevens, Jeffrey R.

    2014-01-01

    What are the dynamics and regularities underlying social contact, and how can contact with the people in one's social network be predicted? In order to characterize distributional and temporal patterns underlying contact probability, we asked 40 participants to keep a diary of their social contacts for 100 consecutive days. Using a memory framework previously used to study environmental regularities, we predicted that the probability of future contact would follow in systematic ways from the frequency, recency, and spacing of previous contact. The distribution of contact probability across the members of a person's social network was highly skewed, following an exponential function. As predicted, it emerged that future contact scaled linearly with frequency of past contact, proportionally to a power function with recency of past contact, and differentially according to the spacing of past contact. These relations emerged across different contact media and irrespective of whether the participant initiated or received contact. We discuss how the identification of these regularities might inspire more realistic analyses of behavior in social networks (e.g., attitude formation, cooperation). PMID:24475073

  4. Temporal patterns of infiltration into a water repellent soil under field conditions

    NASA Astrophysics Data System (ADS)

    Ward, Phil; Roper, Margaret; Micin, Shayne; Jongepier, Ramona

    2014-05-01

    Water repellency causes substantial economic losses for farmers in southern Australia through impacts on crop growth and weed germination. However, recent research has demonstrated that laboratory measurements of water repellency may not be a reliable indicator of the severity of symptoms experienced in the field. In particular, crop residue retention and minimal soil disturbance led to increased water repellency, but was also associated with higher soil water contents measured at strategic times of the year. Little is known about the temporal patterns of soil water storage close to the soil surface in a water repellent sand. In this research we measured soil water content at a depth of 0.05 m at 15-minute intervals from June 2011 to October 2012, under various treatment combinations of residue retention and soil disturbance. Measurements were made in both 'crop row' and 'crop inter-row' positions. For a rainfall event (9.2 mm) in March 2012, prior to crop seeding, plots previously established with no-till absorbed significantly more water (increase in soil water content of 0.074 v/v) than plots conventionally cultivated (0.038 v/v). In June 2012 (12.6 mm), 4 weeks after crop seeding, tillage was again significant, and there was a significant interaction between tillage and 'row' or 'inter-row' position. These results demonstrate the importance of crop management in modifying the response of water repellent soils to rainfall in the field.

  5. Conserved temporal patterns of microRNA expression in Drosophila support a developmental hourglass model.

    PubMed

    Ninova, Maria; Ronshaugen, Matthew; Griffiths-Jones, Sam

    2014-09-01

    The spatiotemporal control of gene expression is crucial for the successful completion of animal development. The evolutionary constraints on development are particularly strong for the mid-embryonic stage when body segments are specified, as evidenced by a high degree of morphological and protein-coding gene conservation during this period--a phenomenon known as the developmental hourglass. The discovery of microRNA-mediated gene control revealed an entirely new layer of complexity of the molecular networks that orchestrate development. However, the constraints on microRNA developmental expression and evolution, and the implications for animal evolution are less well understood. To systematically explore the conservation of microRNAs during development, we carried out a genome-wide comparative study of microRNA expression levels throughout the ontogenesis of two divergent fruit flies, Drosophila melanogaster and D. virilis. We show that orthologous microRNAs display highly similar temporal profiles regardless of their mutation rates, suggesting that the timely expression of microRNA genes can be more constrained than their sequence. Furthermore, transitions between key developmental events in the different species are accompanied by conserved shifts in microRNA expression profiles, with the mid-embryonic period between gastrulation and segmentation characterized by the highest similarity of microRNA expression. The conservation of microRNA expression therefore displays an hourglass pattern similar to that observed for protein-coding genes. PMID:25169982

  6. Temporal patterns of gene expression in developing maize endosperm identified through transcriptome sequencing

    PubMed Central

    Li, Guosheng; Wang, Dongfang; Yang, Ruolin; Logan, Kyle; Chen, Hao; Zhang, Shanshan; Skaggs, Megan I.; Lloyd, Alan; Burnett, William J.; Laurie, John D.; Hunter, Brenda G.; Dannenhoffer, Joanne M.; Larkins, Brian A.; Drews, Gary N.; Wang, Xiangfeng; Yadegari, Ramin

    2014-01-01

    Endosperm is a filial structure resulting from a second fertilization event in angiosperms. As an absorptive storage organ, endosperm plays an essential role in support of embryo development and seedling germination. The accumulation of carbohydrate and protein storage products in cereal endosperm provides humanity with a major portion of its food, feed, and renewable resources. Little is known regarding the regulatory gene networks controlling endosperm proliferation and differentiation. As a first step toward understanding these networks, we profiled all mRNAs in the maize kernel and endosperm at eight successive stages during the first 12 d after pollination. Analysis of these gene sets identified temporal programs of gene expression, including hundreds of transcription-factor genes. We found a close correlation of the sequentially expressed gene sets with distinct cellular and metabolic programs in distinct compartments of the developing endosperm. The results constitute a preliminary atlas of spatiotemporal patterns of endosperm gene expression in support of future efforts for understanding the underlying mechanisms that control seed yield and quality. PMID:24821765

  7. The spatial and temporal distribution pattern of the stoat (Mustela erminea L.).

    PubMed

    Debrot, S; Mermod, C

    1983-08-01

    The distribution and movements of two stoat populations were studied by capture-recapture and tracking in the Swiss Jura Mountains. On the Brévine area in summer 1977 the population was at a high density phase and evenly distributed. A well established intrasexual territorial system was observed, with a high degree of sedentarity in adults. During the decline and the following phase of scarcity, the stoats were progressively restricted to a peat-bog area and the territorial system broke down. The adult males became transient and a high degree of dispersal was recorded among the juveniles. On the Val de Ruz area, the population was fairly stable and the stoats had home ranges and movements adapted to habitat characteristics. Adult males in March-April and juveniles moved around considerably. These aspects of the spatio-temporal distribution pattern of Mustela erminea are discussed in relation to the main factors affecting it, such as population density, habitat, sex and age, activity, and seasons. PMID:25024150

  8. Patterns of spatial and temporal distribution of the asparagus miner (Diptera: Agromyzidae): implications for management.

    PubMed

    Morrison, William R; Szendrei, Zsofia

    2013-06-01

    The asparagus miner is an obligatory feeder on asparagus and a putative vector for pathogenic fungi implicated in the early decline of asparagus fields. To date, the distribution of the asparagus miner over space and time is poorly understood. Our study evaluated the spatial and temporal pattern of adult asparagus miners in commercial asparagus fields in Michigan in 2011 and 2012. We sampled adults and damage weekly during the growing season using yellow sticky traps outside, at the edge, and inside commercial fields. Yellow sticky traps at each trapping location were placed at the canopy and ground level to determine vertical distribution of adults. During the first generation, adults were more evenly distributed throughout the field. In the second generation, adults were more commonly found on the edge of the field. Overall, there was a greater percent of mining damage near the edge of the field. Additionally, three times as many asparagus miners were found in the canopy compared with ground-level traps. There were 12 times as many asparagus miner adults on edges bordered by another asparagus field than on ones bordered by forest. Taken together, our results indicate that while asparagus miner management in the beginning of the growing season should focus on the entire field, in the latter half of the season, growers could save money and resources by targeting miner adults at the edges of fields. Finally, conserving the remaining naturally forested landscape and planting borders of trees may help ameliorate pest pressure in asparagus fields. PMID:23865186

  9. Temporal patterns in the intertidal faunal community at the mouth of a tropical estuary.

    PubMed

    Lacerda, C H F; Barletta, M; Dantas, D V

    2014-11-01

    The use of intertidal sandy beaches by fish and macrocrustaceans was studied at different temporal scales at the mouth of a tropical estuary. Samples were taken along the lunar and diel cycles in the late dry and rainy seasons. Fish assemblage (number of species, density and biomass), crustaceans and wrack biomass, showed significant interactions among all studied factors, and the combination of moon phase and diel cycle, resulting in different patterns of environmental variables (depth, water temperature and dissolved oxygen), affected habitat use by the different species. Variances in faunal community were detected between seasons, stimulated by salinity fluctuations from freshwater input during the rainy season. These differences suggest an important cycling of habitats and an increase in connectivity between adjacent habitats (estuary and coastal waters). Moreover, the results showed that this intertidal sandy beach also provides an alternative nursery and protected shallow-water area for the initial development phase of many marine and estuarine species. In addition, this intertidal habitat plays an important role in the maintenance of the ecological functioning of the estuarine-coastal ecosystem continuum. PMID:25315884

  10. Temporal-Spatial Neural Activation Patterns Linked to Perceptual Encoding of Emotional Salience

    PubMed Central

    Todd, Rebecca M.; Taylor, Margot J.; Robertson, Amanda; Cassel, Daniel B.; Doesberg, Sam M.; Lee, Daniel H.; Shek, Pang N.; Pang, Elizabeth W.

    2014-01-01

    It is well known that we continuously filter incoming sensory information, selectively allocating attention to what is important while suppressing distracting or irrelevant information. Yet questions remain about spatiotemporal patterns of neural processes underlying attentional biases toward emotionally significant aspects of the world. One index of affectively biased attention is an emotional variant of an attentional blink (AB) paradigm, which reveals enhanced perceptual encoding for emotionally salient over neutral stimuli under conditions of limited executive attention. The present study took advantage of the high spatial and temporal resolution of magnetoencephalography (MEG) to investigate neural activation related to emotional and neutral targets in an AB task. MEG data were collected while participants performed a rapid stimulus visual presentation task in which two target stimuli were embedded in a stream of distractor words. The first target (T1) was a number and the second (T2) either an emotionally salient or neutral word. Behavioural results replicated previous findings of greater accuracy for emotionally salient than neutral T2 words. MEG source analyses showed that activation in orbitofrontal cortex, characterized by greater power in the theta and alpha bands, and dorsolateral prefrontal activation were associated with successful perceptual encoding of emotionally salient relative to neutral words. These effects were observed between 250 and 550 ms, latencies associated with discrimination of perceived from unperceived stimuli. These data suggest that important nodes of both emotional salience and frontoparietal executive systems are associated with the emotional modulation of the attentional blink. PMID:24727751

  11. Temporal Patterns in Bivalve Excurrent Flow Under Varying Ambient Flow Conditions

    NASA Astrophysics Data System (ADS)

    Delavan, S. K.; Webster, D. R.

    2008-11-01

    The predator-prey relationship between blue crabs (Callinectes sapidus) and bivalve clams (Mercenaria mercenaria) is mediated by the transport of metabolites released by the prey (clams) and transported downstream as a passive scalar. This study focuses on how the prey behavior contributes to the information available within the odorant plume. Clams may modify factors such as excurrent flux, flow unsteadiness, and siphon height and diameter. A Particle Image Velocimetry (PIV) system has been used to quantify the temporal patterns in the excurrent jet of the bivalve siphon under varying ambient flow conditions. According to a spectral analysis of siphon excurrent velocity time records, there is a low frequency periodic component that could contribute to the mixing of clam metabolites through the generation of persistent jet vorticies. Also, fractal analysis of the velocity time records shows that as the ambient velocity increases the excurrent velocity becomes more correlated and less random. These results suggest that for high ambient flow a low frequency periodicity may be sufficient to promote the mixing and dilution of metabolites. In contrast, for low ambient flow more random siphon excurrent velocity may be required to reduce the amount of information available to predators in the downstream odorant plume.

  12. Fish in a ring: spatio-temporal pattern formation in one-dimensional animal groups.

    PubMed

    Abaid, Nicole; Porfiri, Maurizio

    2010-10-01

    In this work, we study the collective behaviour of fish shoals in annular domains. Shoal mates are modelled as self-propelled particles moving on a discrete lattice. Collective decision-making is determined by information exchange among neighbours. Neighbourhoods are specified using the perceptual limit and numerosity of fish. Fish self-propulsion and obedience to group decisions are described through random variables. Spatio-temporal schooling patterns are measured using coarse observables adapted from the literature on coupled oscillator networks and features of the time-varying network describing the fish-to-fish information exchange. Experiments on zebrafish schooling in an annular tank are used to validate the model. Effects of group size and obedience parameter on coarse observables and network features are explored to understand the implications of perceptual numerosity and spatial density on fish schooling. The proposed model is also compared with a more traditional metric model, in which the numerosity constraint is released and fish interactions depend only on physical configurations. Comparison shows that the topological regime on which the proposed model is constructed allows for interpreting characteristic behaviours observed in the experimental study that are not captured by the metric model. PMID:20413559

  13. Spatial and temporal patterns of particulate matter sources and pollution in four communities in Accra, Ghana.

    PubMed

    Rooney, Michael S; Arku, Raphael E; Dionisio, Kathie L; Paciorek, Christopher; Friedman, Ari B; Carmichael, Heather; Zhou, Zheng; Hughes, Allison F; Vallarino, Jose; Agyei-Mensah, Samuel; Spengler, John D; Ezzati, Majid

    2012-10-01

    Sources of air pollution in developing country cities include transportation and industrial pollution, biomass fuel use, and re-suspended dust from unpaved roads. We examined the spatial patterns of particulate matter (PM) and its sources in four neighborhoods of varying socioeconomic status (SES) in Accra. PM data were from 1 week of morning and afternoon mobile and stationary air pollution measurements in each of the study neighborhoods. PM(2.5) and PM(10) were measured continuously, with matched GPS coordinates. Data on biomass fuel use were from the Ghana 2000 population and housing census and from a census of wood and charcoal stoves along the mobile monitoring paths. We analyzed the associations of PM with sources using a mixed-effects regression model accounting for temporal and spatial autocorrelation. After adjusting for other factors, the density of wood stoves, fish smoking, and trash burning along the mobile monitoring path as well as road capacity and surface were associated with higher PM(2.5). Road capacity and road surface variables were also associated with PM(10), but the association with biomass sources was weak or absent. While wood stoves and fish smoking were significant sources of air pollution, addressing them would require financial and physical access to alternative fuels for low-income households and communities. PMID:22846770

  14. Conserved Temporal Patterns of MicroRNA Expression in Drosophila Support a Developmental Hourglass Model

    PubMed Central

    Ninova, Maria; Ronshaugen, Matthew; Griffiths-Jones, Sam

    2014-01-01

    The spatiotemporal control of gene expression is crucial for the successful completion of animal development. The evolutionary constraints on development are particularly strong for the mid-embryonic stage when body segments are specified, as evidenced by a high degree of morphological and protein-coding gene conservation during this period—a phenomenon known as the developmental hourglass. The discovery of microRNA-mediated gene control revealed an entirely new layer of complexity of the molecular networks that orchestrate development. However, the constraints on microRNA developmental expression and evolution, and the implications for animal evolution are less well understood. To systematically explore the conservation of microRNAs during development, we carried out a genome-wide comparative study of microRNA expression levels throughout the ontogenesis of two divergent fruit flies, Drosophila melanogaster and D. virilis. We show that orthologous microRNAs display highly similar temporal profiles regardless of their mutation rates, suggesting that the timely expression of microRNA genes can be more constrained than their sequence. Furthermore, transitions between key developmental events in the different species are accompanied by conserved shifts in microRNA expression profiles, with the mid-embryonic period between gastrulation and segmentation characterized by the highest similarity of microRNA expression. The conservation of microRNA expression therefore displays an hourglass pattern similar to that observed for protein-coding genes. PMID:25169982

  15. The use of satellite data for monitoring temporal and spatial patterns of fire: a comprehensive review

    NASA Astrophysics Data System (ADS)

    Lasaponara, R.

    2009-04-01

    Remotely sensed (RS) data can fruitfully support both research activities and operative monitoring of fire at different temporal and spatial scales with a synoptic view and cost effective technologies. "The contribution of remote sensing (RS) to forest fires may be grouped in three categories, according to the three phases of fire management: (i) risk estimation (before fire), (ii) detection (during fire) and (iii) assessment (after fire)" Chuvieco (2006). Relating each phase, wide research activities have been conducted over the years. (i) Risk estimation (before fire) has been mainly based on the use of RS data for (i) monitoring vegetation stress and assessing variations in vegetation moisture content, (ii) fuel type mapping, at different temporal and spatial scales from global, regional down to a local scale (using AVHRR, MODIS, TM, ASTER, Quickbird images and airborne hyperspectral and LIDAR data). Danger estimation has been mainly based on the use of AVHRR (onborad NOAA), MODIS (onboard TERRA and AQUA), VEGETATION (onboard SPOT) due to the technical characteristics (i.e. spectral, spatial and temporal resolution). Nevertheless microwave data have been also used for vegetation monitoring. (ii) Detection: identification of active fires, estimation of fire radiative energy and fire emission. AVHRR was one of the first satellite sensors used for setting up fire detection algorithms. The availbility of MODIS allowed us to obtain global fire products free downloaded from NASA web site. Sensors onboard geostationary satellite platforms, such as GOES, SEVIRI, have been used for fire detection, to obtain a high temporal resolution (at around 15 minutes) monitoring of active fires. (iii) Post fire damage assessment includes: burnt area mapping, fire emission, fire severity, vegetation recovery, fire resilience estimation, and, more recently, fire regime characterization. Chuvieco E. L. Giglio, C. Justice, 2008 Global charactrerization of fire activity: toward defining fire regimes from Earth observation data Global Change Biology vo. 14. doi: 10.1111/j.1365-2486.2008.01585.x 1-15, Chuvieco E., P. Englefield, Alexander P. Trishchenko, Yi Luo Generation of long time series of burn area maps of the boreal forest from NOAA-AVHRR composite data. Remote Sensing of Environment, Volume 112, Issue 5, 15 May 2008, Pages 2381-2396 Chuvieco Emilio 2006, Remote Sensing of Forest Fires: Current limitations and future prospects in Observing Land from Space: Science, Customers and Technology, Advances in Global Change Research Vol. 4 pp 47-51 De Santis A., E. Chuvieco Burn severity estimation from remotely sensed data: Performance of simulation versus empirical models, Remote Sensing of Environment, Volume 108, Issue 4, 29 June 2007, Pages 422-435. De Santis A., E. Chuvieco, Patrick J. Vaughan, Short-term assessment of burn severity using the inversion of PROSPECT and GeoSail models, Remote Sensing of Environment, Volume 113, Issue 1, 15 January 2009, Pages 126-136 García M., E. Chuvieco, H. Nieto, I. Aguado Combining AVHRR and meteorological data for estimating live fuel moisture content Remote Sensing of Environment, Volume 112, Issue 9, 15 September 2008, Pages 3618-3627 Ichoku C., L. Giglio, M. J. Wooster, L. A. Remer Global characterization of biomass-burning patterns using satellite measurements of fire radiative energy. Remote Sensing of Environment, Volume 112, Issue 6, 16 June 2008, Pages 2950-2962. Lasaponara R. and Lanorte, On the capability of satellite VHR QuickBird data for fuel type characterization in fragmented landscape Ecological Modelling Volume 204, Issues 1-2, 24 May 2007, Pages 79-84 Lasaponara R., A. Lanorte, S. Pignatti,2006 Multiscale fuel type mapping in fragmented ecosystems: preliminary results from Hyperspectral MIVIS and Multispectral Landsat TM data, Int. J. Remote Sens., vol. 27 (3) pp. 587-593. Lasaponara R., V. Cuomo, M. F. Macchiato, and T. Simoniello, 2003 .A self-adaptive algorithm based on AVHRR multitemporal data analysis for small active fire detection.n International Journal of Remote Sen

  16. Age-related changes in trunk neuromuscular activation patterns during a controlled functional transfer task include amplitude and temporal synergies.

    PubMed

    Quirk, D Adam; Hubley-Kozey, Cheryl L

    2014-12-01

    While healthy aging is associated with physiological changes that can impair control of trunk motion, few studies examine how spinal muscle responses change with increasing age. This study examined whether older (over 65 years) compared to younger (20-45 years) adults had higher overall amplitude and altered temporal recruitment patterns of trunk musculature when performing a functional transfer task. Surface electromyograms from twelve bilateral trunk muscle (24) sites were analyzed using principal component analysis, extracting amplitude and temporal features (PCs) from electromyographic waveforms. Two PCs explained 96% of the waveform variance. Three factor ANOVA models tested main effects (group, muscle and reach) and interactions for PC scores. Significant (p<.0125) group interactions were found for all PC scores. Post hoc analysis revealed that relative to younger adults, older adults recruited higher agonist and antagonistic activity, demonstrated continuous activation levels in specific muscle sites despite changing external moments, and had altered temporal synergies within abdominal and back musculature. In summary both older and younger adults recruit highly organized activation patterns in response to changing external moments. Differences in temporal trunk musculature recruitment patterns suggest that older adults experience different dynamic spinal stiffness and loading compared to younger adults during a functional lifting task. PMID:25457424

  17. Nathan Becker, UCSB (KITP Pattern Conf 8-20-03) Spatio-temporal chaos in rotating Rayleigh-Benard convection Page 1 Nathan Becker, UCSB (KITP Pattern Conf 8-20-03) Spatio-temporal chaos in rotating Rayleigh-Benard convection Page 2

    E-print Network

    Ahlers, Guenter

    -Benard convection Page 1 #12;Nathan Becker, UCSB (KITP Pattern Conf 8-20-03) Spatio-temporal chaos in rotating Rayleigh-Benard convection Page 2 #12;Nathan Becker, UCSB (KITP Pattern Conf 8-20-03) Spatio-temporal chaos in rotating Rayleigh-Benard convection Page 3 #12;Nathan Becker, UCSB (KITP Pattern Conf 8-20-03) Spatio

  18. Automated pattern analysis: A newsilent partner in insect acoustic detection studies

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This seminar reviews methods that have been developed for automated analysis of field-collected sounds used to estimate pest populations and guide insect pest management decisions. Several examples are presented of successful usage of acoustic technology to map insect distributions in field environ...

  19. Acoustic Modal Patterns and Striations (AMPS) experiment G-325, Norfolk Public Schools

    NASA Technical Reports Server (NTRS)

    Young, Joy W.

    1995-01-01

    This paper will describe how high school students with the guidance of volunteer mentors were able to successfully complete an acoustics space experiment. Some of the NORSTAR program strategies used to effectively accomplish this goal will be discussed. The experiment and present status of results will be explained.

  20. Discovering temporal patterns in water quality time series, focusing on floods with the LDA method

    NASA Astrophysics Data System (ADS)

    Hélène Aubert, Alice; Tavenard, Romain; Emonet, Rémi; Malinowski, Simon; Guyet, Thomas; Quiniou, René; Odobez, Jean-Marc; Gascuel-Odoux, Chantal

    2013-04-01

    Studying floods has been a major issue in hydrological research for years. It is often done in terms of water quantity but it is also of interest in terms of water quality. Stream chemistry is a mix of solutes. They originate from various sources in the catchment, reach the stream by various flow pathways and are transformed by biogeochemical reactions at different locations. Therefore, we hypothesized that reaction of the stream chemistry to a rainfall event is not unique but varies according to the season (1), and the global meteorological conditions of the year (2). Identifying a typology of temporal chemical patterns of reaction to a rainfall event is a way to better understand catchment processes at the flood time scale. To answer this issue, we applied a probabilistic model (Latent Dirichlet Allocation or LDA (3)) mining recurrent sequential patterns to a dataset of floods. The dataset is 12 years long and daily recorded. It gathers a broad range of parameters from which we selected rainfall, discharge, water table depth, temperature as well as nitrate, dissolved organic carbon, sulphate and chloride concentrations. It comes from a long-term hydrological observatory (AgrHys, western France) located at Kervidy-Naizin. A set of 472 floods was automatically extracted (4). From each flood, a document has been generated that is made of a set of "hydrological words". Each hydrological word corresponds to a measurement: it is a triplet made of the considered variable, the time at which the measurement is made (relative to the beginning of the flood), and its magnitude (that can be low, medium or high). The documents are used as input data to the LDA algorithm. LDA relies on spotting co-occurrences (as an alternative to the more traditional study of correlation) between words that appear within the flood documents. It has two nice properties that are its ability to easily deal with missing data and its additive property that allows a document to be seen as a mixture of several flood patterns. The output of LDA is a set of patterns that can easily be represented in graphics. These patterns correspond to typical reactions to rainfall events. The patterns themselves are carefully studied, as well as their repartition along the year and along the 12 years of the dataset. The novelties are fourfold. First, as a methodological point of view, we learn that hydrological data can be analyzed with this LDA model giving a typology of a multivariate chemical signature of floods. Second, we outline that chemistry parameters are sufficient to obtain meaningful patterns. There is no need to include hydro-meteorological parameters to define the patterns. However, hydro-meteorological parameters are useful to understand the processes leading to these patterns. Third, our hypothesis of seasonal specific reaction to rainfall is verified, moreover detailed; so is our hypothesis of different reactions to rainfall for years with different hydro-meteorological conditions. Fourth, this method allows the consideration of overlapping floods that are usually not studied. We would recommend the use of such model to study chemical reactions of stream after rainfall events, or more broadly after any hydrological events. The typology that has been provided by this method is a kind of bar code of water chemistry during floods. It could be well suited to compare different geographical locations by using the same patterns and analysing the resulting different pattern distributions. (1) Aubert, A.H. et al., 2012. The chemical signature of a livestock farming catchment: synthesis from a high-frequency multi-element long term monitoring. HESSD, 9(8): 9715 - 9741. (2) Aubert, A.H., Gascuel-Odoux, C., Merot, P., 2013. Annual hysteresis of water quality: A method to analyse the effect of intra- and inter-annual climatic conditions. Journal of Hydrology, 478(0): 29-39. (3) Blei, D. M.; Ng, A. Y.; Jordan, M. I., 2003. Latent Dirichlet allocation. Journal of Machine Learning Research, 3(4-5): 993-1022. (4) de Lavenne, A., Cudennec, C., Streamflow velocity

  1. [Spatial and temporal variation patterns in aquatic macroinvertebrates of Tecocomulco Lake, Hidalgo (México)].

    PubMed

    Rico-Sánchez, Axel Eduardo; Rodríguez-Romero, Alexis Joseph; López-López, Eugenia; Sedeño-Díaz, Jacinto Elías

    2014-04-01

    Lake Tecocomulco, Hidalgo, is a relic of the ancient lakes ofAnahuac, important for the conservation of resident and migratory birds. However, the composition of aquatic macroinvertebrates is unknown; this is an important gap in conservation as they play an important role in the food web. This study analyzed the spatial and temporal variations in macroinvertebrate assemblages and their relationship with habitat characteristics. We carried out four monitoring campaigns covering the rainy and dry seasons. The monitoring was conducted at six study sites (four in the littoral zone and two in the middle part of the lake), environmental factors were recorded at each study site, water samples were collected for their physical and chemical analysis and aquatic macroinvertebrates were collected. A principal component analysis (PCA) was used to group study sites based on physical and chemical characteristics. Richness of taxa was analysed with rarefaction. We assessed the importance value index of each taxon (considering their frequency of occurrence and abundance). Similarity analyzes were performed between study sites and similarity of taxa with indices of Jaccard and Bray-Curtis, respectively. We performed a canonical correspondence analysis (CCA) between environmental factors and macroinvertebrate taxa. The PCA showed a marked seasonal variation represented by warm periods, with high values of conductivity, alkalinity, hardness, sulfates, and macronutrients (N and P) and the cold period with low values. We found a total of 26 taxa of aquatic macroinvertebrates and the highest richness was found in August. The Jaccard similarity analysis found differences between the littoral area and the limnetic zone, which differ also in the composition of macrophytes. The littoral zone had the highest taxa richness of macroinvertebrates and macrophytes, while the lowest diversity was found in the offshore zone. The CCA related physicochemical characteristics of the water body with macroinvertebrate taxa showing the influence of both physicochemical characteristics and the composition of macrophytes in the spatio-temporal patterns of aquatic macroinvertebrates in the lake. The dominance of Corixidae highlights a strong grazing activity in the lake and in turn suggests an important amount of food available for higher trophic levels. Our study shows that the macroinvertebrates of Tecocomulco Lake have spatial and seasonal variations that are related to both environmental and biotic factors with groups being dominant. PMID:25189071

  2. Spatial and Temporal Pattern of Rift Valley Fever Outbreaks in Tanzania; 1930 to 2007

    PubMed Central

    Sindato, Calvin; Karimuribo, Esron D.; Pfeiffer, Dirk U.; Mboera, Leonard E. G.; Kivaria, Fredrick; Dautu, George; Bernard, Bett; Paweska, Janusz T.

    2014-01-01

    Background Rift Valley fever (RVF)-like disease was first reported in Tanzania more than eight decades ago and the last large outbreak of the disease occurred in 2006–07. This study investigates the spatial and temporal pattern of RVF outbreaks in Tanzania over the past 80 years in order to guide prevention and control strategies. Materials and Methods A retrospective study was carried out based on disease reporting data from Tanzania at district or village level. The data were sourced from the Ministries responsible for livestock and human health, Tanzania Meteorological Agency and research institutions involved in RVF surveillance and diagnosis. The spatial distribution of outbreaks was mapped using ArcGIS 10. The space-time permutation model was applied to identify clusters of cases, and a multivariable logistic regression model was used to identify risk factors associated with the occurrence of outbreaks in the district. Principal Findings RVF outbreaks were reported between December and June in 1930, 1947, 1957, 1960, 1963, 1968, 1977–79, 1989, 1997–98 and 2006–07 in 39.2% of the districts in Tanzania. There was statistically significant spatio-temporal clustering of outbreaks. RVF occurrence was associated with the eastern Rift Valley ecosystem (OR?=?6.14, CI: 1.96, 19.28), total amount of rainfall of >405.4 mm (OR?=?12.36, CI: 3.06, 49.88), soil texture (clay [OR?=?8.76, CI: 2.52, 30.50], and loam [OR?=?8.79, CI: 2.04, 37.82]). Conclusion/Significance RVF outbreaks were found to be distributed heterogeneously and transmission dynamics appeared to vary between areas. The sequence of outbreak waves, continuously cover more parts of the country. Whenever infection has been introduced into an area, it is likely to be involved in future outbreaks. The cases were more likely to be reported from the eastern Rift Valley than from the western Rift Valley ecosystem and from areas with clay and loam rather than sandy soil texture. PMID:24586433

  3. Geospatial and temporal patterns of annual cholera outbreaks in Matlab, Bangladesh

    NASA Astrophysics Data System (ADS)

    Majumder, M. S.; de Klerk, K.; Meyers, D.

    2012-12-01

    Cholera is a waterborne diarrheal disease endemic to Bangladesh, resulting in 1 million diagnoses annually. Such disease burden results in incalculable lost wages and treatment expenses, taken from the pockets of an already impoverished society. Two seasonally correlated outbreaks of cholera occur in Bangladesh every year. In the spring and early summer, the Bay of Bengal - which serves as a natural reservoir for the cholera bacteria - flows inland, causing the first outbreak amongst coastal communities. Waste containing the cholera bacteria enters the sewage system and remains untreated due to poor water and sanitation infrastructure. Therefore, during the following monsoon season, flooding of cholera-contaminated sewage into drinking water sources results in a second outbreak. Though considered common knowledge among local populations, this geographic and temporal progression has not been empirically verified in the current literature. The aim of our ongoing study is to systematically analyze the seasonal trajectory of endemic cholera in Bangladesh. This paper discusses the results obtained from a comprehensive survey of available cholera data from the International Centre of Diarrheal Disease Research, Bangladesh (ICDDR,B) in Matlab, Bangladesh. Matlab thana is a near-coastal community that consists of 142 villages. Monsoon season takes place from June through October. Due to its proximity to the Meghna River, which opens into the Bay of Bengal, the area experiences significant flooding during these months. Using 10 years of geographically referenced cholera data, cases were plotted in time and space. Preliminary patterns suggest that villages closer to the Meghna River experience the majority of the area's cholera outbreaks and that case count is highest in late spring and late fall. April/May and November/December represent 25% and 23% of total annual case counts respectively. Moreover, villages further from the coastline demonstrate 57% higher relative prevalence in fall than in the spring. Such initial results demonstrate great promise in advancing our present knowledge of endemic cholera in Bangladesh. By improving our understanding of cholera proliferating in time and space, disease mitigation resources can be distributed to the most susceptible areas when they need them most. The next step forward for our ongoing study involves the use of mobile health (mHealth) case surveillance and cloud computing for real-time geographic and temporal cholera data acquisition.

  4. Spatial-temporal patterns in Mediterranean carnivore road casualties: Consequences for mitigation

    USGS Publications Warehouse

    Grilo, C.; Bissonette, J.A.; Santos-Reis, M.

    2009-01-01

    Many carnivores have been seriously impacted by the expansion of transportation systems and networks; however we know little about carnivore response to the extent and magnitude of road mortality, or which age classes may be disproportionately impacted. Recent research has demonstrated that wildlife-vehicle-collisions (WVC) involving carnivores are modulated by temporal and spatial factors. Thus, we investigated road mortality on a guild of small and medium-sized carnivores in southern Portugal using road-kill data obtained from a systematic 36 months monitoring period along highways (260 km) and national roads (314 km) by addressing the following questions: (a) which species and age class are most vulnerable to WVC? (b) are there temporal and/or spatial patterns in road-kill? and (c) which life-history and/or spatial factors influence the likelihood of collisions? We recorded a total of 806 carnivore casualties, which represented an average of 47 ind./100 km/year. Red fox and stone marten had the highest mortality rates. Our findings highlight three key messages: (1) the majority of road-killed individuals were adults of common species; (2) all carnivores, except genets, were more vulnerable during specific life-history phenological periods: higher casualties were observed when red fox and stone marten were provisioning young, Eurasian badger casualties occurred more frequently during dispersal, and higher Egyptian mongoose mortality occurred during the breeding period; and (3) modeling demonstrated that favorable habitat, curves in the road, and low human disturbance were major contributors to the deadliest road segments. Red fox carcasses were more likely to be found on road sections with passages distant from urban areas. Conversely, stone marten mortalities were found more often on national roads with high of cork oak woodland cover; Egyptian mongoose and genet road-kills were found more often on road segments close to curves. Based on our results, two key mitigation measures should help to reduce WVC in Portugal. The first involves the improvement of existing crossings with buried and small mesh size fence to guide the individuals towards to the passages, in road segments with high traffic volume (>1200 vehicles/night) and located in preferred carnivore habitats. The second mitigation involves cutting or removal of dense vegetation in verges of road segments with curves to aid motorists in seeing animals about to cross. ?? 2008 Elsevier Ltd.

  5. Soft computing analysis of the possible correlation between temporal and energy release patterns in seismic activity

    NASA Astrophysics Data System (ADS)

    Konstantaras, Anthony; Katsifarakis, Emmanouil; Artzouxaltzis, Xristos; Makris, John; Vallianatos, Filippos; Varley, Martin

    2010-05-01

    This paper is a preliminary investigation of the possible correlation of temporal and energy release patterns of seismic activity involving the preparation processes of consecutive sizeable seismic events [1,2]. The background idea is that during periods of low-level seismic activity, stress processes in the crust accumulate energy at the seismogenic area whilst larger seismic events act as a decongesting mechanism releasing considerable energy [3,4]. A dynamic algorithm is being developed aiming to identify and cluster pre- and post- seismic events to the main earthquake following on research carried out by Zubkov [5] and Dobrovolsky [6,7]. This clustering technique along with energy release equations dependent on Richter's scale [8,9] allow for an estimate to be drawn regarding the amount of the energy being released by the seismic sequence. The above approach is being implemented as a monitoring tool to investigate the behaviour of the underlying energy management system by introducing this information to various neural [10,11] and soft computing models [1,12,13,14]. The incorporation of intelligent systems aims towards the detection and simulation of the possible relationship between energy release patterns and time-intervals among consecutive sizeable earthquakes [1,15]. Anticipated successful training of the imported intelligent systems may result in a real-time, on-line processing methodology [1,16] capable to dynamically approximate the time-interval between the latest and the next forthcoming sizeable seismic event by monitoring the energy release process in a specific seismogenic area. Indexing terms: pattern recognition, long-term earthquake precursors, neural networks, soft computing, earthquake occurrence intervals References [1] Konstantaras A., Vallianatos F., Varley M.R. and Makris J. P.: ‘Soft computing modelling of seismicity in the southern Hellenic arc', IEEE Geoscience and Remote Sensing Letters, vol. 5 (3), pp. 323-327, 2008 [2] Eneva M. and Ben-Zion Y.: ‘Techniques and parameters to analyze seismicity patterns associated with large earthquakes', Geophysics Res., vol. 102, pp. 17785-17795, 1997a [3] Habermann R. E.: ‘Precursory seismic quiescence: past, present and future', Pure Applied Geophysics, vol. 126, pp. 279-318, 1988 [4] Matthews M. V. and Reasenberg P. A.: ‘Statistical methods for investigating quiescence and other temporal seismicity patterns', Pure Applied Geophysics, vol. 126, pp. 357-372, 1988 [5] Zubkov S. I.: ‘The appearance times of earthquake precursors', Izv. Akad. Nauk SSSR Fiz. Zemli (Solid Earth), No. 5, pp. 87-91, 1987 [6] Dobrovolsky I. P., Zubkov S. I. and Miachkin V. I.: ‘Estimation of the size of earthquake preparation zones', Pageoph, vol. 117, pp. 1025-1044, 1979 [7] Dobrovolsky I. P., Gershenzon N. I. And Gokhberg M. B.: ‘Theory of electrokinetic effects occurring at the final stage in the preparation of a tectonic earthquake', Physics of the Earth and Planetary Interiors, vol. 57, pp. 144-156, 1989 [8] Richter C. F.: ‘Elementary Seismology', W.H.Freeman and Co., San Francisco, 1958 [9] Choy G. L. and Boatwright J. L.: ‘Global patterns of radiated seismic energy and apparent stress', Journal of Geophysical Research, vol. 84 (B5), pp. 2348-2350, 1995 [10] Haykin S.: ‘Neural Networks', 2nd Edition, Prentice Hall, 1999 [11] Jang J., Sun T. and Mizutany E.: ‘Neuro-fuzzy and soft computing', Prentice Hall, Upper Saddle River, NJ, 1997 [12] Konstantaras A., Varley M.R., Vallianatos F., Collins G. and Holifield P.: ‘Detection of weak seismo-electric signals upon the recordings of the electrotelluric field by means of neuron-fuzzy technology', IEEE Geoscience and Remote Sensing Letters, vol. 4 (1), 2007 [13] Konstantaras A., Varley M.R., Vallianatos F., Collins G. and Holifield P.: ‘Neuro-fuzzy prediction-based adaptive filtering applied to severely distorted magnetic field recordings', IEEE Geoscience and Remote Sensing Letters, vol. 3 (4), 2006 [14] Maravelakis E., Bilalis N., Keith J. and Antoniadis A.: ‘Measuring and Benchmarking the Innovativene

  6. Sequence-based mapping approach to spatio-temporal snow patterns from MODIS time-series applied to Scotland

    NASA Astrophysics Data System (ADS)

    Poggio, Laura; Gimona, Alessandro

    2015-02-01

    Snow cover and its monitoring are important because of the impact on important environmental variables, hydrological circulation and ecosystem services. For regional snow cover mapping and monitoring, the MODIS satellite sensors are particularly appealing. However cloud presence is an important limiting factor. This study addressed the problem of cloud cover for time-series in a boreal-Atlantic region where melting and re-covering of snow often do not follow the usual alpine-like patterns. A key requirement in this context was to apply improved methods to deal with the high cloud cover and the irregular spatio-temporal snow occurrence, through exploitation of space-time correlation of pixel values. The information contained in snow presence sequences was then used to derive summary indices to describe the time series patterns. Finally it was tested whether the derived indices can be considered an accurate summary of the snow presence data by establishing and evaluating their statistical relations with morphology and the landscape. The proposed cloud filling method had a good agreement (between 80 and 99%) with validation data even with a large number of pixels missing. The sequence analysis algorithm proposed takes into account the position of the states to fully consider the temporal dimension, i.e. the order in which a certain state appears in an image sequence compared to its neighbourhoods. The indices that were derived from the sequence of snow presence proved useful for describing the general spatio-temporal patterns of snow in Scotland as they were well related (more than 60% of explained deviance) with environmental information such as morphology supporting their use as a summary of snow patterns over time. The use of the derived indices is an advantage because of data reduction, easier interpretability and capture of sequence position-wise information (e.g. importance of short term fall/melt cycles). The derived seven clusters took into account the temporal patterns of the snow presence and they were well separated both spatially and according to the snow patterns and the environmental information. In conclusion, the use of sequences proved useful for analysing different spatio-temporal patterns of snow that could be related to other environmental information to characterize snow regimes regions in Scotland and to be integrated with ground measures for further hydrological and climatological analysis as baseline data for climate change models.

  7. Spatio-temporal patterns of schistosomiasis japonica in lake and marshland areas in China: the effect of snail habitats.

    PubMed

    Hu, Yi; Gao, Jie; Chi, Meina; Luo, Can; Lynn, Henry; Sun, Liqian; Tao, Bo; Wang, Decheng; Zhang, Zhijie; Jiang, Qingwu

    2014-09-01

    The progress of the integrated control policy for schistosomiasis implemented since 2005 in China, which is aiming at reducing the roles of bovines and humans as infection sources, may be challenged by persistent presence of infected snails in lake and marshland areas. Based on annual parasitologic data for schistosomiasis during 2004-2011 in Xingzi County, a spatio-temporal kriging model was used to investigate the spatio-temporal pattern of schistosomiasis risk. Results showed that environmental factors related to snail habitats can explain the spatio-temporal variation of schistosomiasis. Predictive maps of schistosomiasis risk illustrated that clusters of the disease fluctuated during 2004-2008; there was an extensive outbreak in 2008 and attenuated disease occurrences afterwards. An area with an annually constant cluster of schistosomiasis was identified. Our study suggests that targeting snail habitats located within high-risk areas for schistosomiasis would be an economic and sustainable way of schistosomiasis control in the future. PMID:24980498

  8. Using Conditional Analysis to Investigate Spatial and Temporal patterns in Upland Rainfall

    NASA Astrophysics Data System (ADS)

    Sakamoto Ferranti, Emma Jayne; Whyatt, James Duncan; Timmis, Roger James

    2010-05-01

    The seasonality and characteristics of rainfall in the UK are altering under a changing climate. Summer rainfall is generally decreasing whereas winter rainfall is increasing, particularly in northern and western areas (Maraun et al., 2008) and recent research suggests these rainfall increases are amplified in upland areas (Burt and Ferranti, 2010). Conditional analysis has been used to investigate these rainfall patterns in Cumbria, an upland area in northwest England. Cumbria was selected as an example of a topographically diverse mid-latitude region that has a predominately maritime and westerly-defined climate. Moreover it has a dense network of more than 400 rain gauges that have operated for periods between 1900 and present day. Cumbria has experienced unprecedented flooding in the past decade and understanding the spatial and temporal changes in this and other upland regions is important for water resource and ecosystem management. The conditional analysis method examines the spatial and temporal variations in rainfall under different synoptic conditions and in different geographic sub-regions (Ferranti et al., 2009). A daily synoptic typing scheme, the Lamb Weather Catalogue, was applied to classify rainfall into different weather types, for example: south-westerly, westerly, easterly or cyclonic. Topographic descriptors developed using GIS were used to classify rain gauges into 6 directionally-dependant geographic sub-regions: coastal, windward-lowland, windward-upland, leeward-upland, leeward-lowland, secondary upland. Combining these classification methods enabled seasonal rainfall climatologies to be produced for specific weather types and sub-regions. Winter rainfall climatologies were constructed for all 6 sub-regions for 3 weather types - south-westerly (SW), westerly (W), and cyclonic (C); these weather types contribute more than 50% of total winter rainfall. The frequency of wet-days (>0.3mm), the total winter rainfall and the average wet day rainfall amount were analysed for each rainfall sub-region and weather type from 1961-2007 (Ferranti et al., 2010). The conditional analysis showed total rainfall under SW and W weather types to be increasing, with the greatest increases observed in the upland sub-regions. The increase in total SW rainfall is driven by a greater occurrence of SW rain days, and there has been little change to the average wet-day rainfall amount. The increase in total W rainfall is driven in part by an increase in the frequency of wet-days, but more significantly by an increase in the average wet-day rainfall amount. In contrast, total rainfall under C weather types has decreased. Further analysis will investigate how spring, summer and autumn rainfall climatologies have changed for the different weather types and sub-regions. Conditional analysis that combines GIS and synoptic climatology provides greater insights into the processes underlying readily available meteorological data. Dissecting Cumbrian rainfall data under different synoptic and geographic conditions showed the observed changes in winter rainfall are not uniform for the different weather types, nor for the different geographic sub-regions. These intricate details are often lost during coarser resolution analysis, and conditional analysis will provide a detailed synopsis of Cumbrian rainfall processes against which Regional Climate Model (RCM) performance can be tested. Conventionally RCMs try to simulate composite rainfall over many different weather types and sub-regions and by undertaking conditional validation the model performance for individual processes can be tested. This will help to target improvements in model performance, and ultimately lead to better simulation of rainfall in areas of complex topography. BURT, T. P. & FERRANTI, E. J. S. (2010) Changing patterns of heavy rainfall in upland areas: a case study from northern England. Atmospheric Environment, [in review]. FERRANTI, E. J. S., WHYATT, J. D. & TIMMIS, R. J. (2009) Development and application of topographic descriptors for conditional a

  9. Analysis and Monitoring of the Spatio-temporal Aerosol Patterns over Bangladesh

    NASA Astrophysics Data System (ADS)

    Mamun, M.; Islam, M.

    2012-12-01

    Nowadays climate change is the burning issue and atmospheric aerosols are vital parameter of the global climate system. So, atmospheric aerosols are one of the hot topics for present scientific research. Most remote sensing methods retrieve aerosol optical depth (AOD) to assess the aerosols and their various effects on environmental and climate system. However, there is lack of studies dealing with monitoring of aerosol patterns over Bangladesh. In this research, we have analyzed the spatial and temporal variations in aerosol load over Bangladesh, using MODerate resolution Imaging Spectroradiometer (MODIS) Level 3 remote sensing data. A Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model was used to generate a backward trajectory in order to identify the origins of air masses, with the aim of understanding these spatial and temporal variabilities in aerosol concentrations. During the last decade, AODs have increased across Bangladesh and revealed a higher AOD concentration in western part but a much cleaner environment in eastern part. An assessment of monthly mean variations in AOD has exhibited maximum AODs in June and minimum AODs in October. Looking over seasonal variations during the last decade over Bangladesh showed maximum AOD values during the summer, while minimum AOD values showed during the post monsoon also an evidence of a decreasing AOD trend showed during the monsoon can be owing to an increase in monsoonal rainfall in Bangladesh, while all other seasons showed increasing trends. Northwestern part of Bangladesh has showed at the top of AOD concentration in winter season during the year 2010. Dense fog activities in northern part of Bangladesh may be the causes of this high AOD distribution. We also documented, the regional AOD variations over seven different divisions of Bangladesh, for which Dhaka and Sylhet divisions showed decreasing trends where all others showed increasing trends. Annual mean AODs have highest levels in Rajshahi and Khulna and lowest level in Sylhet. Back trajectory analysis indicates that Bangladesh is mainly affected by the pollutions and desert dust of India combining with sea salt particles blown from the Arabian Sea. The sources of air masses were arriving at lower altitudes (500m, 1500m) mainly in western India and Indian subcontinent but higher altitude (2500m) air masses were loading especially in winter season from far western regions, such as Europe and various sub-Sahara region of Africa. However, an exceptional result was observed in post monsoon of 2010 that different flow patterns of air masses were observed that the air masses were arriving in Sylhet from southeast in the direction, the sources of air masses were in coastal region of Thailand and the boarder region of Myanmar and China. The air masses were arriving at several divisions in different seasons from different distances and directions owing to the variations of wind velocities and wind directions. These studies become important and useful to proceed about climate change in Bangladesh. However, more and more studies are required to understand about atmospheric aerosol properties and their climate impacts.

  10. Spatio-temporal patterns in land use and management affecting surface runoff response of agricultural catchments—A review

    NASA Astrophysics Data System (ADS)

    Fiener, P.; Auerswald, K.; Van Oost, K.

    2011-05-01

    Surface runoff and associated erosion processes adversely affect soil and surface water quality. There is increasing evidence that a sound understanding of spatial-temporal dynamics of land use and management are crucial to understanding surface runoff processes and underpinning mitigation strategies. In this review, we synthesise the effects of (1) temporal patterns of land management of individual fields, and (2) spatio-temporal interaction of several fields within catchments by applying semivariance analysis, which allows the extent and range of the different patterns to be compared. Consistent effects of management on the temporal dynamics of surface runoff of individual fields can be identified, some of which have been incorporated into small-scale hydrological models. In contrast, the effects of patchiness, the spatial organisation of patches with different soil hydrological properties, and the effects of linear landscape structures are less well understood and are rarely incorporated in models. The main challenge for quantifying these effects arises from temporal changes within individual patches, where the largest contrasts usually occur in mid-summer and cause a seasonally varying effect of patchiness on the overall catchment response. Some studies indicate that increasing agricultural patchiness, due to decreasing field sizes, reduces the catchment-scale response to rainfall, especially in cases of Hortonian runoff. Linear structures associated with patchiness of fields (e.g. field borders, ditches, and ephemeral gullies) may either increase or decrease the hydraulic connectivity within a catchment. The largest gap in research relates to the effects and temporal variation of patch interaction, the influence of the spatial organisation of patches and the interaction with linear structures. In view of the substantial changes in the structure of agricultural landscapes occurring throughout the world, it is necessary to improve our knowledge of the influence of patchiness and connectivity, and to implement this knowledge in new modelling tools.

  11. Spatial and temporal patterns of dissolved organic matter optical properties across large rivers in Africa

    NASA Astrophysics Data System (ADS)

    Lambert, Thibault; Darchambeau, François; Vieira Borges, Alberto; Alhou, Bassirou; Mbega, Jean-Daniel; Teodoru, Cristian; Marwick, Trent Richard; Bouillon, Steven

    2014-05-01

    Tropical rivers have disproportionally high carbon transport and outgassing compared to temperate and Arctic rivers. Yet the cycling of dissolved organic matter (DOM) within these systems is still poorly studied with the exception of the Amazon basin. The chromophoric or colored dissolved organic matter (CDOM) is the fraction of DOM that absorbs ultraviolet and visible light. As the biochemical nature of DOM (and CDOM) defines its optical properties, optical measurements are particularly useful to assess the composition of DOM in freshwater and hence can be applied as proxies for assessments of DOM sources and its biogeochemical role. However, less is known on how specific optical characteristics can be applied as proxies and how these proxies vary from one system to another. In this study we compared concentrations and stable isotopic signature of dissolved organic carbon with optical properties of DOM from diverse tropical river systems across the African continent including the Congo basin, the Zambezi basin, the Ogooué basin and the Niger basin. These major rivers of the African continent were monitored for long period (from 1-3 years) at biweekly frequency. This large dataset allowed us to compare the spatial and temporal patterns of DOM quality along various environmental gradients, including hydrology, river size, terrestrial vegetation and connectivity to terrestrial inputs. The optical proxies presented and discussed in this study include absorption coefficients a(?) at different wavelength (254, 300, 350 and 440 nm), spectral slopes (S275-295and S350-400), the spectral slope ratio (SR=S275-295:S350-400) and the a(250):a(365) ratio.

  12. Comparison of Observed Spatio-temporal Aftershock Patterns with Earthquake Simulator Results

    NASA Astrophysics Data System (ADS)

    Kroll, K.; Richards-Dinger, K. B.; Dieterich, J. H.

    2013-12-01

    Due to the complex nature of faulting in southern California, knowledge of rupture behavior near fault step-overs is of critical importance to properly quantify and mitigate seismic hazards. Estimates of earthquake probability are complicated by the uncertainty that a rupture will stop at or jump a fault step-over, which affects both the magnitude and frequency of occurrence of earthquakes. In recent years, earthquake simulators and dynamic rupture models have begun to address the effects of complex fault geometries on earthquake ground motions and rupture propagation. Early models incorporated vertical faults with highly simplified geometries. Many current studies examine the effects of varied fault geometry, fault step-overs, and fault bends on rupture patterns; however, these works are limited by the small numbers of integrated fault segments and simplified orientations. The previous work of Kroll et al., 2013 on the northern extent of the 2010 El Mayor-Cucapah rupture in the Yuha Desert region uses precise aftershock relocations to show an area of complex conjugate faulting within the step-over region between the Elsinore and Laguna Salada faults. Here, we employ an innovative approach of incorporating this fine-scale fault structure defined through seismological, geologic and geodetic means in the physics-based earthquake simulator, RSQSim, to explore the effects of fine-scale structures on stress transfer and rupture propagation and examine the mechanisms that control aftershock activity and local triggering of other large events. We run simulations with primary fault structures in state of California and northern Baja California and incorporate complex secondary faults in the Yuha Desert region. These models produce aftershock activity that enables comparison between the observed and predicted distribution and allow for examination of the mechanisms that control them. We investigate how the spatial and temporal distribution of aftershocks are affected by changes to model parameters such as shear and normal stress, rate-and-state frictional properties, fault geometry, and slip rate.

  13. Nest site attributes and temporal patterns of northern flicker nest loss: effects of predation and competition.

    PubMed

    Fisher, Ryan J; Wiebe, Karen L

    2006-04-01

    To date, most studies of nest site selection have failed to take into account more than one source of nest loss (or have combined all sources in one analysis) when examining nest site characteristics, leaving us with an incomplete understanding of the potential trade-offs that individuals may face when selecting a nest site. Our objectives were to determine whether northern flickers (Colaptes auratus) may experience a trade-off in nest site selection in response to mammalian nest predation and nest loss to a cavity nest competitor (European starling, Sturnus vulgaris). We also document within-season temporal patterns of these two sources of nest loss with the hypothesis that flickers may also be constrained in the timing of reproduction under both predatory and competitive influence. Mammalian predators frequently depredated flicker nests that were: lower to the ground, less concealed by vegetation around the cavity entrance and at the base of the nest tree, closer to coniferous forest edges and in forest clumps with a high percentage of conifer content. Proximity to coniferous edges or coniferous trees increased the probability of nest predation, but nests near conifers were less likely to be lost to starlings. Flickers may thus face a trade-off in nest site selection with respect to safety from predators or competitors. Models suggested that peaks of nest predation and nest loss to eviction occurred at the same time, although a competing model suggested that the peak of nest loss to starlings occurred 5 days earlier than the peak of mammalian predation. Differences in peaks of mammalian predation and loss to starlings may constrain any adjustment in clutch initiation date by flickers to avoid one source of nest loss. PMID:16323016

  14. Temporal and spatial paleoproductivity patterns associated with Eastern Mediterranean sapropels: paleoceanographic significance.

    NASA Astrophysics Data System (ADS)

    Gallego-Torres, D.; Martinez-Ruiz, F.; Meyers, P. A.; Paytan, A.; Jimenez-Espejo, F. J.; Ortega-Huertas, M.

    2007-12-01

    Deposition of Eastern Mediterranean sapropels has been discussed in terms of enhanced primary productivity and/or preferential preservation due to anoxic conditions in the deep basin. However, formation of these organic enriched layers is not homogeneous across the basin and through time, and temporal and spatial patterns can be observed in organic carbon concentrations and depositional conditions. We used a transect of ODP sites in the Eastern Mediterranean for the study of such variations, covering the area of major influence of the European continent and incoming waters from the Western Mediterranean basin (Ionian basin, Site 964), a region of influence of the Nile River (Levantine basin, Site 967), the central region of the basin with minor continental influence (Mediterranean Ridge, Site 969), and shallower bathymetries (Eratosthenes Seamount, Site 966). A set of paleoproductivity related proxies has been applied in order to reconstruct the paleoceanographic conditions that led to the formation of sapropels. As a whole, sapropel formation corresponds to wetter periods occurring during precessional minima and appears associated to increased productivity, evidenced by Ba/Al, and TOC-Ba mass accumulation rates maxima. ?13C data indicate intensified carbon fixation during organic carbon entrapment in sediment, where as low ?15N values provide evidence of nitrogen fixation through cyanobacteria activity as a source of increased primary and export productivity. This overwhelming export productivity led to the depletion of deep water dissolved oxygen, thus improving organic matter preservation. The above mentioned proxies show that sapropels represent periods of high productivity in an otherwise oligotrophic basin. This productivity was initiated and sustained by a change in bacterial community to nitrogen-fixing organism favored by intensified continental drainage and nutrient input. In agreement to this observation, sapropel onset generally occurred earlier in the Levantine basin, directly influenced by variations in the Nile River discharge, and progressively spread toward the western part of the basin. Thus, this change in paleoceanographic conditions is ultimately climatically driven and the evolution of the regional climate affects the intensity of the sapropel formation for the last 3 My. Intensified productivity and enhanced preservation is observed during sapropel deposition from the middle Pliocene until the lower Pleistocene. Productivity maxima occur during the late Pleistocene, coinciding with highest recorded sedimentary rate, and a relatively weak increase is observed during the deposition of the Holocene sapropel. This pattern implies that the rates of deep-water ventilation and of continental erosion generally increased in the eastern Mediterranean region as climate cooled since the mid-Pliocene.

  15. Mapping the Spatio-Temporal Pattern of the Mammalian Target of Rapamycin (mTOR) Activation in Temporal Lobe Epilepsy

    PubMed Central

    Zhang, Dan; Yao, Yuan; Dou, Wan-Chen; Jin, Li-Ri; Wu, Li-Wen; Xu, Qi

    2012-01-01

    Growing evidence from rodent models of temporal lobe epilepsy (TLE) indicates that dysregulation of the mammalian target of rapamycin (mTOR) pathway is involved in seizures and epileptogenesis. However, the role of the mTOR pathway in the epileptogenic process remains poorly understood. Here, we used an animal model of TLE and sclerotic hippocampus from patients with refractory TLE to determine whether cell-type specific activation of mTOR signaling occurs during each stage of epileptogenesis. In the TLE mouse model, we found that hyperactivation of the mTOR pathway is present in distinct hippocampal subfields at three different stages after kainate-induced seizures, and occurs in neurons of the granular and pyramidal cell layers, in reactive astrocytes, and in dispersed granule cells, respectively. In agreement with the findings in TLE mice, upregulated mTOR was observed in the sclerotic hippocampus of TLE patients. All sclerotic hippocampus (n?=?13) exhibited widespread reactive astrocytes with overactivated mTOR, some of which invaded the dispersed granular layer. Moreover, two sclerotic hippocampus exhibited mTOR activation in some of the granule cells, which was accompanied by cell body hypertrophy. Taken together, our results indicate that mTOR activation is most prominent in reactive astrocytes in both an animal model of TLE and the sclerotic hippocampus from patients with drug resistant TLE. PMID:22761730

  16. T-pattern analysis for the study of temporal structure of animal and human behavior: a comprehensive review.

    PubMed

    Casarrubea, M; Jonsson, G K; Faulisi, F; Sorbera, F; Di Giovanni, G; Benigno, A; Crescimanno, G; Magnusson, M S

    2015-01-15

    A basic tenet in the realm of modern behavioral sciences is that behavior consists of patterns in time. For this reason, investigations of behavior deal with sequences that are not easily perceivable by the unaided observer. This problem calls for improved means of detection, data handling and analysis. This review focuses on the analysis of the temporal structure of behavior carried out by means of a multivariate approach known as T-pattern analysis. Using this technique, recurring sequences of behavioral events, usually hard to detect, can be unveiled and carefully described. T-pattern analysis has been successfully applied in the study of various aspects of human or animal behavior such as behavioral modifications in neuro-psychiatric diseases, route-tracing stereotypy in mice, interaction between human subjects and animal or artificial agents, hormonal-behavioral interactions, patterns of behavior associated with emesis and, in our laboratories, exploration and anxiety-related behaviors in rodents. After describing the theory and concepts of T-pattern analysis, this review will focus on the application of the analysis to the study of the temporal characteristics of behavior in different species from rodents to human beings. This work could represent a useful background for researchers who intend to employ such a refined multivariate approach to the study of behavior. PMID:25280983

  17. Depth Depending Pattern Recognition (DDPR) - a tool for visualization of spatial and temporal similarities of properties in sediment cores

    NASA Astrophysics Data System (ADS)

    Büttner, Olaf; Baborowski, Martina

    2013-04-01

    Depth Depending Pattern Recognition (DDPR) is a new simple tool for the visualization of spatial and temporal similarities of measured parameters in a set of sediment cores. It was developed to support the multivariate analysis of data of sediment cores taken in a still water area of the River Elbe [1]. The idea behind is the assumption that correlations in spatial or temporal distributions of environmental parameters can be visualized by different ways and that a distance between two patterns can be defined with mathematical methods. So the similarity of two patterns can be quantified and assessed by a catalog of subjective rules. Generally, defining one reference pattern, the computation of a distance matrix for different parameter distributions is easily possible. Consequently, the three main steps of the algorithm are a) the creation of the pattern from the measurements, b) the definition of the distance calculation and c) the interpretation and assessment of the distance matrix. The method can be used in addition to classical uni- or multivariate statistical methods like regression analysis, principal component analysis, correlation analysis etc. DDPR supports hypothesis testing and explanation of relationships. In the poster DDPR is explained and the method is presented for two examples, an artificial one and one with data from sediment cores. Reference [1] Baborowski M., Büttner O., Morgenstern P., Jancke T., Westrich B. (2012) Spatial variability of metal pollution in groyne fields of the Middle Elbe - Implications for sediment monitoring, Environmental Pollution, 167,115-123

  18. Analysis of the meter of acoustic musical signals

    Microsoft Academic Search

    Anssi P. Klapuri; Antti J. Eronen; Jaakko T. Astola

    2006-01-01

    A method is decribed which analyzes the basic pattern of beats in a piece of music, the musical meter. The analysis is performed jointly at three different time scales: at the temporally atomic tatum pulse level, at the tactus pulse level which corresponds to the tempo of a piece, and at the musical measure level. Acoustic signals from arbitrary musical

  19. Understanding spatio-temporal mobility patterns for seniors, child/student and adult using smart card data

    NASA Astrophysics Data System (ADS)

    Huang, X.; Tan, J.

    2014-11-01

    Commutes in urban areas create interesting travel patterns that are often stored in regional transportation databases. These patterns can vary based on the day of the week, the time of the day, and commuter type. This study proposes methods to detect underlying spatio-temporal variability among three groups of commuters (senior citizens, child/students, and adults) using data mining and spatial analytics. Data from over 36 million individual trip records collected over one week (March 2012) on the Singapore bus and Mass Rapid Transit (MRT) system by the fare collection system were used. Analyses of such data are important for transportation and landuse designers and contribute to a better understanding of urban dynamics. Specifically, descriptive statistics, network analysis, and spatial analysis methods are presented. Descriptive variables were proposed such as density and duration to detect temporal features of people. A directed weighted graph G ≡ (N , L, W) was defined to analyze the global network properties of every pair of the transportation link in the city during an average workday for all three categories. Besides, spatial interpolation and spatial statistic tools were used to transform the discrete network nodes into structured human movement landscape to understand the role of transportation systems in urban areas. The travel behaviour of the three categories follows a certain degree of temporal and spatial universality but also displays unique patterns within their own specialties. Each category is characterized by their different peak hours, commute distances, and specific locations for travel on weekdays.

  20. Spatial and temporal patterns of larval dispersal in a coral-reef fish metapopulation: evidence of variable reproductive success.

    PubMed

    Pusack, Timothy J; Christie, Mark R; Johnson, Darren W; Stallings, Christopher D; Hixon, Mark A

    2014-07-01

    Many marine organisms can be transported hundreds of kilometres during their pelagic larval stage, yet little is known about spatial and temporal patterns of larval dispersal. Although traditional population-genetic tools can be applied to infer movement of larvae on an evolutionary timescale, large effective population sizes and high rates of gene flow present serious challenges to documenting dispersal patterns over shorter, ecologically relevant, timescales. Here, we address these challenges by combining direct parentage analysis and indirect genetic analyses over a 4-year period to document spatial and temporal patterns of larval dispersal in a common coral-reef fish: the bicolour damselfish (Stegastes partitus). At four island locations surrounding Exuma Sound, Bahamas, including a long-established marine reserve, we collected 3278 individuals and genotyped them at 10 microsatellite loci. Using Bayesian parentage analysis, we identified eight parent-offspring pairs, thereby directly documenting dispersal distances ranging from 0 km (i.e., self-recruitment) to 129 km (i.e., larval connectivity). Despite documenting substantial dispersal and gene flow between islands, we observed more self-recruitment events than expected if the larvae were drawn from a common, well-mixed pool (i.e., a completely open population). Additionally, we detected both spatial and temporal variation in signatures of sweepstakes and Wahlund effects. The high variance in reproductive success (i.e., 'sweepstakes') we observed may be influenced by seasonal mesoscale gyres present in the Exuma Sound, which play a prominent role in shaping local oceanographic patterns. This study documents the complex nature of larval dispersal in a coral-reef fish, and highlights the importance of sampling multiple cohorts and coupling both direct and indirect genetic methods in order disentangle patterns of dispersal, gene flow and variable reproductive success. PMID:24917250

  1. Earthquake-like patterns of acoustic emission in crumpled plastic sheets

    NASA Astrophysics Data System (ADS)

    Mendes, R. S.; Malacarne, L. C.; Santos, R. P. B.; Ribeiro, H. V.; Picoli, S., Jr.

    2010-10-01

    We report remarkable similarities in the output signal of two distinct out-of-equilibrium physical systems —earthquakes and the intermittent acoustic noise emitted by crumpled plastic sheets, i.e. Biaxially Oriented Polypropylene (BOPP) films. We show that both signals share several statistical properties including the distribution of energy, distribution of energy increments for distinct time scales, distribution of return intervals and correlations in the magnitude and sign of energy increments. This analogy is consistent with the concept of universality in complex systems and could provide some insight on the mechanisms behind the complex behavior of earthquakes.

  2. Composition, structural characteristics and temporal patterns of fish assemblages in non-tidal Mediterranean lagoons: A case study

    NASA Astrophysics Data System (ADS)

    Maci, S.; Basset, A.

    2009-08-01

    The importance of transitional water ecosystems as nursery habitats and feeding grounds for fish species is well-known. Detailed studies of colonization patterns of fish guilds in response to biotic and abiotic drivers are however unevenly distributed among ecosystem types. We address here the temporal variability of fish assemblages in small non-tidal lagoons in the Mediterranean basin. The study was carried out at the Acquatina lagoon (Lecce, Italy) where four stations, situated in two habitat types along a confinement gradient, were sampled twice per month for one year with fyke nets. Forty-five taxa ranging across 20 families were collected, with the most abundant species, Atherina boyeri, accounting for more than 95% of total abundance. Pooling all species together (excluding sand smelt), the structural features of the assemblage, relative abundance of families, and abundance of individual species all showed significant temporal patterns. Mean abundance peaked in Summer and Autumn and fell in Winter, whereas taxonomic richness and diversity were highest in Summer and lowest in Spring. Within the fish assemblage, multivariate ordination showed temporal segregation of species belonging to the same family or genus and expected to be functionally similar, suggesting that they avoid competition for space and resources by timing inward migration and peak occurrence differently. Of the environmental driving forces, which also showed temporal patterns of variation, salinity was the main factor affecting the distribution of individuals and species. The catch of young individuals of several marine species confirmed the role of this small lagoon as a nursery and feeding area, and emphasized the need for further studies.

  3. Application of pattern recognition techniques to the identification of aerospace acoustic sources

    NASA Technical Reports Server (NTRS)

    Fuller, Chris R.; Obrien, Walter F.; Cabell, Randolph H.

    1988-01-01

    A pattern recognition system was developed that successfully recognizes simulated spectra of five different types of transportation noise sources. The system generates hyperplanes during a training stage to separate the classes and correctly classify unknown patterns in classification mode. A feature selector in the system reduces a large number of features to a smaller optimal set, maximizing performance and minimizing computation.

  4. Patterns of venom production and temporal polyethism in workers of Jerdon's jumping ant, Harpegnathos saltator.

    PubMed

    Haight, Kevin L

    2012-12-01

    Ants are chemical factories, and among their more noticeable products are their venoms. Though many studies have addressed the properties and activities of ant venoms, basic venom-related physiological questions, such as how venom production and replacement may vary with age, are rarely addressed. The answers to these questions are fundamental to understanding the physiological capabilities of these organisms, as well as the parameters within which potential optimization of their investment in venom production must take place. The only previous investigation into venom production in ants found it to be limited to early life in workers of the fire ant, Solenopsis invicta (Haight and Tschinkel, 2003). Because similar studies have not been conducted for comparison, it is unclear whether or not this is a common physiological pattern in ants. As a parsimonious way to address this question, and, more generally, to increase the currently scant information available regarding the venom-producing capabilities of ants, the longevity, temporal polyethism, age-related venom production, and age-related venom replacement capabilities of workers of Jerdon's jumping ant, Harpegnathos saltator were investigated. Longevity varied from 10 days to nearly 2 years, with a median lifespan of 206 days. Workers remained in the nest when young, transitioned to outside work (foraging) after 50 days of age, and reached a plateau in their tendency to be outside the nest at 74 days of age. They eclosed with empty venom sacs, filled them by about 57 days of age, and were able to replace venom at all three ages tested (though at a higher rate when aged 100 days than 30 and 206). So, venom-production ability is not limited to early life in H. saltator workers, and aspects of venom physiology and exploratory behavior appear to coincide in a manner likely to result in foraging efficiency benefits; venom sacs reach fullness around the age workers begin their foraging careers, and venom replacement rate is highest around the age workers become the most dedicated foragers. PMID:23041374

  5. Spatio-temporal Patterns and Landscape-Associated Risk of Buruli Ulcer in Akonolinga, Cameroon

    PubMed Central

    Landier, Jordi; Gaudart, Jean; Carolan, Kevin; Lo Seen, Danny; Guégan, Jean-François; Eyangoh, Sara; Fontanet, Arnaud; Texier, Gaëtan

    2014-01-01

    Background Buruli ulcer (BU) is an extensively damaging skin infection caused by Mycobacterium ulcerans, whose transmission mode is still unknown. The focal distribution of BU and the absence of interpersonal transmission suggest a major role of environmental factors, which remain unidentified. This study provides the first description of the spatio-temporal variations of BU in an endemic African region, in Akonolinga, Cameroon. We quantify landscape-associated risk of BU, and reveal local patterns of endemicity. Methodology/Principal Findings From January 2002 to May 2012, 787 new BU cases were recorded in 154 villages of the district of Akonolinga. Incidence per village ranged from 0 (n?=?59 villages) to 10.4 cases/1000 person.years (py); median incidence was 0.4 cases/1,000py. Villages neighbouring the Nyong River flood plain near Akonolinga town were identified as the highest risk zone using the SPODT algorithm. We found a decreasing risk with increasing distance to the Nyong and identified 4 time phases with changes in spatial distribution. We classified the villages into 8 groups according to landscape characteristics using principal component analysis and hierarchical clustering. We estimated the incidence ratio (IR) associated with each landscape using a generalised linear model. BU risk was highest in landscapes with abundant wetlands, especially cultivated ones (IR?=?15.7, 95% confidence interval [95%CI]?=?15.7[4.2–59.2]), and lowest in reference landscape where primary and secondary forest cover was abundant. In intermediate-risk landscapes, risk decreased with agriculture pressure (from IR[95%CI]?=?7.9[2.2–28.8] to 2.0[0.6–6.6]). We identified landscapes where endemicity was stable and landscapes where incidence increased with time. Conclusion/Significance Our study on the largest series of BU cases recorded in a single endemic region illustrates the local evolution of BU and identifies the Nyong River as the major driver of BU incidence. Local differences along the river are explained by wetland abundance and human modification of the environment. PMID:25188464

  6. Spatial and temporal patterns of Pleistocene biogenic sediment accumulation in the Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Moy, C. M.; Bahlburg, H.; Childress, L. B.; Cowan, E. A.; Forwick, M.; Müller, J.; Ribeiro, F.; Ridgway, K. D.; Mix, A. C.

    2013-12-01

    Reconstructing the timing and nature of past changes in aquatic productivity in the Gulf of Alaska (GoA) can shed light on the primary processes driving biogeochemical cycling over geologic timescales. Today, Fe is an important micronutrient that limits primary productivity in surface waters beyond the continental shelf in much of the GoA. However, we have a relatively poor understanding of how Fe-delivery processes, combined with changing climate, environmental, and oceanographic conditions, interact to influence primary production over glacial-interglacial timescales. An important first step is to identify the spatial and temporal patterns of increased productivity in the sediment record. Here, we present sedimentologic and physical property data from IODP Expedition 341 and identify intervals where diatom ooze and diatom-rich mud lithofacies are prevalent during the Pleistocene. Among the Expedition 341 recovered cores, were high-recovery intervals in the outer (Site U1417) and inner (U1418) Surveyor Fan, and from a small slope basin at the edge of the continental shelf (Site U1419). In general, greenish gray diatomaceous ooze (containing >50 % diatoms in smear slides) and diatom-rich mud (>25% diatoms) is found in beds ranging in thickness from 20 to 150 cm, interbedded with gray mud that commonly contains lonestones. Ooze is occasionally found immediately overlying volcanic ash. Compared to non-biogenic mud, diatomaceous sediments are generally characterized by lower magnetic susceptibility, natural gamma ray, bulk density, and higher b* color reflectance. At Site U1417, we observe a frequent occurrence of diatomaceous ooze during the middle Pleistocene relative to the early and late Pleistocene. At Site U1418, intervals containing diatom ooze are less common than at U1417 and biogenic sediments are mainly observed within the late Pleistocene portion of the record. However, higher sedimentation rates at U1418 relative to U1417, and the co-occurrence of sand and interbedded mud and silt indicate that clastic sediment dilution may obscure biogenic sediment contribution. At Site U1419, two prominent ~5 m thick intervals of diatomaceous ooze are found (within the uppermost 5 m and between 80 and 90 m composite depth, respectively). Between these intervals are numerous 20 cm thick intervals of biogenic sediment that were likely deposited during the middle or late Pleistocene based on preliminary shipboard age models. Biogenic intervals observed at Expedition 341 sites may be related to increased productivity driven by a combination of the aforementioned processes, but additional chronological and geochemical constraints are needed from all sites to rule out the role that changing sedimentation rates and/or silica dissolution plays in controlling the distribution of ooze in these records.

  7. Incorporation of treatment plan spatial and temporal dose patterns into a prostate intrafractional motion management strategy

    SciTech Connect

    Zhang Pengpeng; Hunt, Margie; Happersett, Laura; Cox, Brett; Mageras, Gig [Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States); Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 (United States)

    2012-09-15

    Purpose: Periodic MV/KV radiographs taken during volumetric modulated arc therapy (VMAT) for hypofractionated treatment provide guidance in intrafractional motion management. The choice of imaging frequency and timing are key components in delivering the desired dose while reducing associated overhead such as imaging dose, preparation, and processing time. In this project the authors propose a paradigm with imaging timing and frequency based on the spatial and temporal dose patterns of the treatment plan. Methods: A number of control points are used in treatment planning to model VMAT delivery. For each control point, the sensitivity of individual target or organ-at-risk dose to motion can be calculated as the summation of dose degradations given the organ displacements along a number of possible motion directions. Instead of acquiring radiographs at uniform time intervals, MV/KV image pairs are acquired indexed to motion sensitivity. Five prostate patients treated via hypofractionated VMAT are included in this study. Intrafractional prostate motion traces from the database of an electromagnetic tracking system are used to retrospectively simulate the VMAT delivery and motion management. During VMAT delivery simulation patient position is corrected based on the radiographic findings via couch movement if target deviation violates a patient-specific 3D threshold. The violation rate calculated as the percentage of traces failing the clinical dose objectives after motion correction is used to evaluate the efficacy of this approach. Results: Imaging indexed to a 10 s equitime interval and correcting patient position accordingly reduces the violation rate to 19.5% with intervention from 44.5% without intervention. Imaging indexed to the motion sensitivity further reduces the violation rate to 12.1% with the same number of images. To achieve the same 5% violation rate, the imaging incidence can be reduced by 40% by imaging indexed to motion sensitivity instead of time. Conclusions: The simulation results suggest that image scheduling according to the characteristics of the treatment plan can improve the efficiency of intrafractional motion management. Using such a technique, the accuracy of delivered dose during image-guided hypofractionated VMAT treatment can be improved.

  8. What can flux tracking teach us about water age distribution patterns and their temporal dynamics?

    NASA Astrophysics Data System (ADS)

    Hrachowitz, M.; Savenije, H.; Bogaard, T. A.; Tetzlaff, D.; Soulsby, C.

    2013-02-01

    The complex interactions of runoff generation processes underlying the hydrological response of streams remain not entirely understood at the catchment scale. Extensive research has demonstrated the utility of tracers for both inferring flow path distributions and constraining model parameterizations. While useful, the common use of linearity assumptions, i.e. time invariance and complete mixing, in these studies provides only partial understanding of actual process dynamics. Here we use long-term (<20 yr) precipitation, flow and tracer (chloride) data of three contrasting upland catchments in the Scottish Highlands to inform integrated conceptual models investigating different mixing assumptions. Using the models as diagnostic tools in a functional comparison, water and tracer fluxes were then tracked with the objective of exploring the differences between different water age distributions, such as flux and resident water age distributions, and characterizing the contrasting water age pattern of the dominant hydrological processes in the three study catchments to establish an improved understanding of the wetness-dependent temporal dynamics of these distributions. The results highlight the potential importance of partial mixing processes which can be dependent on the hydrological functioning of a catchment. Further, tracking tracer fluxes showed that the various components of a model can be characterized by fundamentally different water age distributions which may be highly sensitive to catchment wetness history, available storage, mixing mechanisms, flow path connectivity and the relative importance of the different hydrological processes involved. Flux tracking also revealed that, although negligible for simulating the runoff response, the omission of processes such as interception evaporation can result in considerably biased water age distributions. Finally, the modeling indicated that water age distributions in the three study catchments do have long, power-law tails, which are generated by the interplay of flow path connectivity, the relative importance of different flow paths as well as by the mixing mechanisms involved. In general this study highlights the potential of customized integrated conceptual models, based on multiple mixing assumptions, to infer system internal transport dynamics and their sensitivity to catchment wetness states.

  9. Analyzing spatial-temporal patterns of motor vehicle crashes using GIS: a case study in Dallas

    E-print Network

    Lu, Bing

    2003-01-01

    This paper uses GIS to analyze the characteristics of temporal and spatial distributions of motor vehicle crashes. These characteristics include that traffic accidents are most likely to occur in the afternoon "rush hour" (4:00 - 6:00PM...

  10. Numerical Study of the Complex Temporal Pattern of Spontaneous Oscillation in Bullfrog Saccular Hair Cells

    NASA Astrophysics Data System (ADS)

    Roongthumskul, Yuttana; Fredrickson-Hemsing, Lea; Kao, Albert; Bozovic, Dolores

    2011-11-01

    Hair bundles of the bullfrog sacculus display spontaneous oscillations that show complex temporal profiles. Quiescent intervals are typically interspersed with oscillations, analogous to bursting behavior observed in neural systems. By introducing slow calcium dynamics into the theoretical model of bundle mechanics, we reproduce numerically the multi-mode oscillations and explore the effects of internal parameters on the temporal profiles and the frequency tuning of their linear response functions. We also study the effects of mechanical overstimulation on the oscillatory behavior.

  11. Déjà-vu in temporal lobe epilepsy: metabolic pattern of cortical involvement in patients with normal brain MRI.

    PubMed

    Guedj, Eric; Aubert, Sandrine; McGonigal, Aileen; Mundler, Olivier; Bartolomei, Fabrice

    2010-06-01

    To contribute to the identification of brain regions involved in déjà-vu, we studied the metabolic pattern of cortical involvement in patients with seizures of temporal lobe origin presenting with or without déjà-vu. Using voxel-based analysis of 18FDG-PET brain scans, we compared glucose metabolic rate of 8 patients with déjà-vu, 8 patients without déjà-vu, and 20 age-matched healthy subjects. Patients were selected after comprehensive non-invasive presurgical evaluation, including normal brain MRI and surface electroclinical features compatible with unilateral temporal lobe epilepsy (TLE). Patients with and without déjà-vu did not differ in terms of age, gender, epilepsy lateralization, epilepsy onset, epilepsy duration, and other subjective ictal manifestations. TLE patients with déjà-vu exhibited ipsilateral hypometabolism of superior temporal gyrus and of parahippocampal region, in the vicinity of perirhinal/entorhinal cortex, in comparison either to healthy subjects or to TLE patients without déjà-vu (p<0.05 FDR-corrected). By contrast, no difference was found between patient subgroups for hypometabolism of hippocampus and amygdala. At an individual-level, in comparison to healthy subjects, hypometabolism of both parahippocampal region and superior temporal gyrus was present in 7/8 patients with déjà-vu. Hippocampal metabolism was spared in 3 of these 7 patients. These findings argue for metabolic dysfunction of a medial-lateral temporal network in patients with déjà-vu and normal brain MRI. Within the medial temporal lobe, specific involvement of the parahippocampal region, often in the absence of hippocampal impairment, suggests that the feeling of familiarity during seizures greatly depends on alteration of the recognition memory system. PMID:20398682

  12. Separation of spatial-temporal patterns ('climatic modes') by combined analysis of really measured and generated numerically vector time series

    NASA Astrophysics Data System (ADS)

    Feigin, A. M.; Mukhin, D.; Volodin, E. M.; Gavrilov, A.; Loskutov, E. M.

    2013-12-01

    The new method of decomposition of the Earth's climate system into well separated spatial-temporal patterns ('climatic modes') is discussed. The method is based on: (i) generalization of the MSSA (Multichannel Singular Spectral Analysis) [1] for expanding vector (space-distributed) time series in basis of spatial-temporal empirical orthogonal functions (STEOF), which makes allowance delayed correlations of the processes recorded in spatially separated points; (ii) expanding both real SST data, and longer by several times SST data generated numerically, in STEOF basis; (iii) use of the numerically produced STEOF basis for exclusion of 'too slow' (and thus not represented correctly) processes from real data. The application of the method allows by means of vector time series generated numerically by the INM RAS Coupled Climate Model [2] to separate from real SST anomalies data [3] two climatic modes possessing by noticeably different time scales: 3-5 and 9-11 years. Relations of separated modes to ENSO and PDO are investigated. Possible applications of spatial-temporal climatic patterns concept to prognosis of climate system evolution is discussed. 1. Ghil, M., R. M. Allen, M. D. Dettinger, K. Ide, D. Kondrashov, et al. (2002) "Advanced spectral methods for climatic time series", Rev. Geophys. 40(1), 3.1-3.41. 2. http://83.149.207.89/GCM_DATA_PLOTTING/GCM_INM_DATA_XY_en.htm 3. http://iridl.ldeo.columbia.edu/SOURCES/.KAPLAN/.EXTENDED/.v2/.ssta/

  13. Spatial and temporal patterns of CO[subscript 2] and CH[subscript 4] fluxes in China's croplands in response to multifactor environmental changes

    E-print Network

    REN, WEI

    The spatial and temporal patterns of CO[subscript 2] and CH[subscript 4] fluxes in China's croplands were investigated and attributed to multifactor environmental changes using the agricultural module of the Dynamic Land ...

  14. Geographic and Demographic Patterns of Alcohol-Related Fatal Traffic Crashes: A Spatial-Temporal Analysis in Texas, 1996-2005

    E-print Network

    Rolland, Gabriel A.

    2010-01-16

    analysis can provide a closer look into trends such as spatial-temporal patterns, clustering and correlations to various factors. Furthermore, Geographic Information Systems (GIS) have enabled researchers to more efficiently interpret and study a large...

  15. Persistent patterns of brain activity: an EEG coherence study of the positive effect of music on spatial-temporal reasoning.

    PubMed

    Sarnthein, J; vonStein, A; Rappelsberger, P; Petsche, H; Rauscher, F H; Shaw, G L

    1997-04-01

    Motivated by predictions from the structured trion model of the cortex, behavioral experiments have demonstrated a causal short-term enhancement of spatial-temporal reasoning in college students following exposure to a Mozart sonata, but not in control conditions. The coherence analysis of electroencephalogram (EEG) recordings is well suited to the neurophysiological investigation of this behavioral enhancement. Here we report the presence of right frontal and left temporo-parietal coherent activity induced by listening to Mozart which carried over into the spatial-temporal tasks in three of our seven subjects. This carry-over effect was compared to EEG coherence analysis of spatial-temporal-tasks after listening to text. We suggest that these EEG coherence results provide the beginnings of understanding of the neurophysiological basis of the causal enhancement of spatial-temporal reasoning by listening to specific music. The observed long-lasting coherent EEG pattern might be evidence for structured sequences in cortical dynamics which extend over minutes. PMID:9175137

  16. The monaural temporal window based on masking period pattern data in school-aged children and adults

    PubMed Central

    Buss, Emily; He, Shuman; Grose, John H.; Hall, Joseph W.

    2013-01-01

    Several lines of evidence indicate that auditory temporal resolution improves over childhood, whereas other data implicate the development of processing efficiency. The present study used the masking period pattern paradigm to examine the maturation of temporal processing in normal-hearing children (4.8 to 10.7 yrs) compared to adults. Thresholds for a brief tone were measured at 6 temporal positions relative to the period of a 5-Hz quasi-square-wave masker envelope, with a 20-dB modulation depth, as well as in 2 steady maskers. The signal was a pure tone at either 1000 or 6500?Hz, and the masker was a band of noise, either spectrally wide or narrow (21.3 and 1.4 equivalent rectangular bandwidths, respectively). Masker modulation improved thresholds more for wide than narrow bandwidths, and adults tended to receive more benefit from modulation than young children. Fits to data for the wide maskers indicated a change in window symmetry with development, reflecting relatively greater backward masking for the youngest listeners. Data for children >6.5 yrs of age appeared more adult-like for the 6500- than the 1000-Hz signal. Differences in temporal window asymmetry with listener age cannot be entirely explained as a consequence of a higher criterion for detection in children, a form of inefficiency. PMID:23464028

  17. High resolution acoustic measurement system and beam pattern reconstruction method for bat echolocation emissions.

    PubMed

    Gaudette, Jason E; Kloepper, Laura N; Warnecke, Michaela; Simmons, James A

    2014-01-01

    Measurements of the transmit beam patterns emitted by echolocating bats have previously been limited to cross-sectional planes or averaged over multiple signals using sparse microphone arrays. To date, no high-resolution measurements of individual bat transmit beams have been reported in the literature. Recent studies indicate that bats may change the time-frequency structure of their calls depending on the task, and suggest that their beam patterns are more dynamic than previously thought. To investigate beam pattern dynamics in a variety of bat species, a high-density reconfigurable microphone array was designed and constructed using low-cost ultrasonic microphones and custom electronic circuitry. The planar array is 1.83?m wide by 1.42?m tall with microphones positioned on a 2.54?cm square grid. The system can capture up to 228 channels simultaneously at a 500?kHz sampling rate. Beam patterns are reconstructed in azimuth, elevation, and frequency for visualization and further analysis. Validation of the array measurement system and post-processing functions is shown by reconstructing the beam pattern of a transducer with a fixed circular aperture and comparing the result with a theoretical model. To demonstrate the system in use, transmit beam patterns of the big brown bat, Eptesicus fuscus, are shown. PMID:24437791

  18. High-order space-time finite element schemes for acoustic and viscodynamic wave equations with temporal decoupling

    PubMed Central

    Banks, H T; Birch, Malcolm J; Brewin, Mark P; Greenwald, Stephen E; Hu, Shuhua; Kenz, Zackary R; Kruse, Carola; Maischak, Matthias; Shaw, Simon; Whiteman, John R

    2014-01-01

    We revisit a method originally introduced by Werder et al. (in Comput. Methods Appl. Mech. Engrg., 190:6685–6708, 2001) for temporally discontinuous Galerkin FEMs applied to a parabolic partial differential equation. In that approach, block systems arise because of the coupling of the spatial systems through inner products of the temporal basis functions. If the spatial finite element space is of dimension D and polynomials of degree r are used in time, the block system has dimension (r + 1)D and is usually regarded as being too large when r > 1. Werder et al. found that the space-time coupling matrices are diagonalizable over for r ?100, and this means that the time-coupled computations within a time step can actually be decoupled. By using either continuous Galerkin or spectral element methods in space, we apply this DG-in-time methodology, for the first time, to second-order wave equations including elastodynamics with and without Kelvin–Voigt and Maxwell–Zener viscoelasticity. An example set of numerical results is given to demonstrate the favourable effect on error and computational work of the moderately high-order (up to degree 7) temporal and spatio-temporal approximations, and we also touch on an application of this method to an ambitious problem related to the diagnosis of coronary artery disease. Copyright © 2014 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons Ltd.

  19. Complex temporal and spatial patterns in nonequilibrium processes. Final report, December 1, 1987--November 30, 1992

    SciTech Connect

    Not Available

    1992-12-31

    Dynamical systems methods have been used to study bifurcations and pattern formation in nonequilibrium systems. Accomplishments during this period include: information-theoretic methods for analyzing chaos, chemical reactors for studying sustained reaction-diffusion patterns, a reactor exploiting pattern formation to extract short- lived intermediate species, observation of bifurcation from periodic to quasiperiodic rotating chemical spiral patterns, observation of a Turing bifurcation (transition from uniform state to a stationary chemical pattern), method for extracting noise strength in ramped convection, self-similar fractal structure of Zn clusters in electrodeposition, and dynamical instability in crack propagation.

  20. Radiative heating of acoustically levitated nano-silica droplets: Internal flow pattern leading to ring or bowl shaped structure

    NASA Astrophysics Data System (ADS)

    Saha, Abhishek; Tijerino, Erick; Kumar, Ranganathan; Basu, Saptarshi

    2010-11-01

    An experimental setup using radiative heating has been used to understand the thermophysical phenomena inside acoustically levitated droplets. In this transformation process, through IR thermography and high speed imaging, events such as vaporization, precipitation have been recorded at high temporal resolution; leading to bowl or ring shaped structures. High solute loading is seen to form high concentration precipitate near the surface with a weak center linkage which results in a horizontal ring formation initially. Droplet recirculation is more effective at lower concentrations, inducing a bridge formation near the center leading to a bowl formation. With non-uniform particle distribution, these structures can experience rupture which modifies the droplet rotational speed with preferential orientation. PIV on sub millimeter sized droplets shows presence of strong single core vortex around droplet center. Study with droplet diameter and viscosity of the liquid leads to the conclusion that the strength of the vortex is dependent on these parameters. Further investigation with LIF confirms preferential accumulation of particles at the bottom of the droplet.

  1. Spatial and temporal patterns of porcine reproductive and respiratory syndrome virus (PRRSV) genotypes in Ontario, Canada, 2004–2007

    PubMed Central

    2014-01-01

    Background The spread of PRRSV among pig herds has been investigated experimentally, but few observational studies have investigated this subject. Because PRRSV is endemic and live modified vaccines are used in Ontario, the spatial and temporal distributions of 6 PRRSV genotypes were investigated in the province during the period from 2004–2007. The purpose was to find evidence of spread of PRRSV genotypes and determine if spread could be attributed to supplier or ownership connections between herds. Sequence information from PRRSV ORF5 and related source-herd demographic information were obtained from diagnostic submissions to the Animal Health Laboratory, University of Guelph. Results A spatial cluster that could not be attributed to supplier or ownership connections among herds in the cluster was detected for RFLP type 1-3-4. Because of genetic dissimilarity among members of the cluster, it was considered to be a result of past spread of the RFLP type. A spatio-temporal cluster detected for RFLP type 1-18-4 was attributed to a shared gilt supplier among the herds in the cluster. Significant spatio-temporal patterns detected for RFLP type 2-5-2, which is considered to be a vaccine-type virus were most likely due to grouping of herds in an ownership that used the corresponding vaccine. Clustering within herd-ownership was a risk factor for presence of five of the six genotypes investigated in the present study. Conclusions Although the literature indicates that PRRSV can spread via aerosol between pig herds, the present study found no strong evidence of this occurring in Ontario. The evidence pointed toward transmission of PRRSV occurring in this population by common sources of animals or similarity of herd ownership, which is a proxy measure for other connections between herds. It is also apparent that the recognition and testing of these connections between herds is a necessary part of interpreting spatio-temporal patterns of PRRSV genotypes. PMID:24708804

  2. Characterizing spatial and temporal patterns of cloud cover and fog inundation for the Northern Channel islands of California

    NASA Astrophysics Data System (ADS)

    Rastogi, Bharat

    The presence of low-lying stratocumulus clouds and fog has been known to modify biophysical and ecological properties in a variety of ecosystems in different climates. This is especially true for California's Channel Islands, where forests are frequently shaded by low-lying clouds or immersed in fog during warm and dry summer months. Previous studies suggest that clouds strongly modulate forest distributions as well as carbon and water budgets in these semi-arid environments by reducing solar insolation and raising relative humidity and thus reducing evapotranspiration, while also potentially supplying water directly to the landscape from fog-drip. While summertime fog and stratus cover in California's Channel Islands can ameliorate summer drought stress and enhance soil water budgets, they often have different spatial and temporal patterns. These differing patterns and the resulting shifts in relative ecological importance of fog and stratus are understudied. The overall objective of this study is to map spatial and temporal distributions of daytime cloud cover frequency for the California Channel Islands, and to predict probabilities of surface cloud (fog) contact and immersion for these islands. The results of this research are significant for water balance modeling, help explain vegetation patterns on the islands, and better identify locations where native vegetation restoration efforts are likely to be most successful.

  3. Temporal Patterns of Subjective Experiences and Self-Regulation during Ramadan Fasting among Elite Archers: A Qualitative Analysis

    PubMed Central

    Roy, Jolly; Hamidan, Shazarina; Singh, Rabindarjeet

    2011-01-01

    Purpose Some major competitions (e.g. London Olympics, 2012) are scheduled during the Ramadan fasting month. Little attention has been given to explore the archers’ performance related subjective experiences with a qualitative method. Therefore, this study addressed individual archers’ subjective experiences within the framework of self-regulation during Ramadan. Methods Eleven elite Malaysian Muslim fasting archers volunteered to participate in the study. Grounded theory was the qualitative approach used to examine the subjective experiences of athletes during Ramadan. Interviews were conducted and inductive content analysis was adopted to identify the temporal patterns of self-regulation of subjective experiences across the fasting period. Results Inductive content analysis identified (a) physical, (b) mental,(c) emotional, (d) behavioral, and (e) spiritual experiences. Overall patterns revealed that experiences associated with physical, emotional, behavioral, and spiritual dimensions dominated in the first phase of fasting, while the mental dimension surfaced increasingly in the latter phase of fasting. Conclusions The trend showed changes in the patterns of experiences among the major domains across the temporal dimension. Athletes reported increased subjective experiences in mental factors toward the latter half of the fasting period. Practitioners should emphasize on mental aspects of training, as these appear to be salient in archery performance. PMID:22375239

  4. Temporal Patterns of Ant Diversity across a Mountain with Climatically Contrasting Aspects in the Tropics of Africa

    PubMed Central

    Munyai, Thinandavha Caswell; Foord, Stefan Hendrik

    2015-01-01

    Factors that drive species richness over space and time are still poorly understood and are often context specific. Identifying these drivers for ant diversity has become particularly relevant within the context of contemporary global change events. We report on a long-term bi-annual (wet and dry seasons), standardized sampling of epigeal ants over a five year period on the mesic and arid aspects of an inselberg (Soutpansberg Mountain Range) in the tropics of Africa. We detail seasonal, annual and long-term trends of species density, test the relative contribution of geometric constraints, energy, available area, climate, local environmental variables, time, and space in explaining ant species density patterns through Generalized Linear Mixed Models (GLMM) where replicates were included as random factors to account for temporal pseudo-replication. Seasonal patterns were very variable and we found evidence of decreased seasonal variation in species density with increased elevation. The extent and significance of a decrease in species density with increased elevation varied with season. Annual patterns point to an increase in ant diversity over time. Ant density patterns were positively correlated with mean monthly temperature but geometric constraints dominated model performance while soil characteristics were minor correlates. These drivers and correlates accounted for all the spatio-temporal variability in the database. Ant diversity was therefore mainly determined by geometric constraints and temperature while soil characteristics (clay and carbon content) accounted for smaller but significant amounts of variation. This study documents the role of season, elevation and their interaction in affecting ant species densities while highlighting the importance of neutral processes and temperature in driving these patterns. PMID:25774670

  5. Spatial and Temporal Patterns of Nitrogen Transport in a Subtropical Urban Coastal Watershed

    NASA Astrophysics Data System (ADS)

    Toor, G.; Banger, K.; Inglett, P.; Stanley, C.

    2010-12-01

    Non-point source pollution is the dominant pathway of nitrogen (N) transport in agriculture as well as urban watersheds. Very little is known about N transport in urban watersheds located in the subtropics. Our objective was to evaluate the spatial and temporal evolution patterns of N forms in streams draining sub-basins, ranging in size from 19 to 350 km2, of an urban watershed located in the Tampa Bay region. We used long-term monthly (1991-2009) and weekly (2009) stream water N concentration data collected from these sub-basins to evaluate the impact of urban development on N transport. Sub-basins were separated in two groups based on urban land uses: developed (18-24% residential, 1-14% built up) and undeveloped (3-11% residential, 1-3% built up). Mean monthly total N concentrations during 1991-2009 were 0.8-2.4 mg L-1 at all sites and were greatest in streams draining developed (1.7-2.4 mg L-1) than undeveloped (0.8-1.2 mg L-1) sub-basins. All the developed and undeveloped sub-basins had a narrow range of organic N concentration (0.60-0.77 mg L-1) in streams; however, percent organic N was about twice as much in streams draining undeveloped (66-71% of total N) than developed (30-44% of total N) sub-basins. On the other hand, both NO3-N concentration and percentage of total N were much greater in developed (0.89-1.66 mg L-1; 53-68% of total N) than undeveloped (0.21-0.37 mg L-1; 25-30% of total N) sub-basins. Among all N forms, mean monthly concentrations of NH4-N were lowest (<0.1 mg L-1; 2-5% of total N). Compared with long-term monthly total N concentrations, weekly total N concentrations were much higher (1.90-2.90 mg L-1) during 2009 high-flow period (June to September), with greater concentrations in developed (2.40-2.95 mg L-1) as compared to undeveloped (1.90-2.06 mg L-1) sub-basins. Concentrations of organic N mirrored a similar trend as total N at all sites. The weekly inorganic N (NO3-N, NH4-N) trends were similar to long-term data, with greater proportions in developed (26-39% of total N) than undeveloped (13-23% of total N) sub-basins. Percent weekly organic N was much greater (65-85% of total N) across all sites as compared to 1991-2009 monthly data (30-71% of total N). Organic N approached 77-85% of total N in undeveloped and 71-75% of total N in developed sub-basins. Organic N forms consists of dissolved organic N (DON; humic substances, amino acids, amino sugars, and tannins) and particulate organic N (PON; partially decomposed organic matter); these forms were measured in weekly samples. The undeveloped sub-basins had much greater concentrations of DON (0.97-1.05 mg L-1, 50-53% of total N) as compared to PON (0.56-0.64 mg L-1, 27-34% of total N). The transport of a specific organic N form whether DON or PON will be determined by the duration and intensity of rainfall-runoff events. For example, high-rainfall events may transport leaf litter and organic matter (that are components of PON) to streams, whereas low-rainfall events may not have enough hydrologic power to transport particulates from land to streams but can mobilize and carry DON to streams.

  6. Temporal control of self-organized pattern formation without morphogen gradients in bacteria

    PubMed Central

    Payne, Stephen; Li, Bochong; Cao, Yangxiaolu; Schaeffer, David; Ryser, Marc D; You, Lingchong

    2013-01-01

    Diverse mechanisms have been proposed to explain biological pattern formation. Regardless of their specific molecular interactions, the majority of these mechanisms require morphogen gradients as the spatial cue, which are either predefined or generated as a part of the patterning process. However, using Escherichia coli programmed by a synthetic gene circuit, we demonstrate here the generation of robust, self-organized ring patterns of gene expression in the absence of an apparent morphogen gradient. Instead of being a spatial cue, the morphogen serves as a timing cue to trigger the formation and maintenance of the ring patterns. The timing mechanism enables the system to sense the domain size of the environment and generate patterns that scale accordingly. Our work defines a novel mechanism of pattern formation that has implications for understanding natural developmental processes. PMID:24104480

  7. Temporal encoding of two-dimensional patterns by single units in primate primary visual cortex. I. Stimulus-response relations.

    PubMed

    Richmond, B J; Optican, L M; Spitzer, H

    1990-08-01

    1. Previously we developed a new approach for investigating visual system neuronal activity in which single neurons are considered to be communication channels transmitting stimulus-dependent codes in their responses. Application of this approach to the stimulus-response relations of inferior temporal (IT) neurons showed that these carry stimulus-dependent information in the temporal modulation as well as in the strength of their responses. IT cortex is a late station in the visual processing stream. Presumably the neuronal properties arise from the properties of the inputs. However, the discovery that IT neuronal spike trains transmit information in stimulus-dependent temporally modulated codes could not be assumed to be true for those earlier stations, so the techniques used in the earlier study were applied to single-striate cortical neurons in the studies reported here. 2. Single-striate cortical neurons were recorded from three awake, fixating rhesus monkeys. The neurons were stimulated by two sets of patterns. The first set was made up of 128 black-and-white patterns based on a complete, orthogonal set of two-dimensional Walsh-Hadamard functions. These stimuli appear as combinations of black-and-white rectangles and squares, and they fully span the range of all possible black-and-white pictures that can be constructed in an 8 x 8 grid. Except for the stimulus that appeared as an all-white or all-black square, each stimulus had equal areas of white and black. The second stimulus set was made up of single bars constructed in the same 8 x 8 grid as the Walsh stimuli. These were presented both as black against a gray background and white against a gray background. The stimuli were centered on the receptive field, and each member of the stimulus set was presented once before any stimulus appeared again. 3. The responses of 21 striate cortical neurons were recorded and analyzed. Two were identified as simple cells and the other 19 as complex cells according to the criteria originally used by Hubel and Wiesel. The stimulus set elicited a wide variety of response strengths and patterns from each neuron. The responses from both the bars and the Walsh set could be used to differentiate and classify simple and complex cells. 4. The responses of both simple and complex cells showed striking stimulus-related strength and temporal modulation. For all of the complex cells there were instances where the responses to a stimulus and its contrast-reversed mate were substantially different in response strength or pattern, or both.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2213122

  8. The structure of spatio-temporal defects in a spiral pattern in the Couette-Taylor flow

    NASA Astrophysics Data System (ADS)

    Ezersky, A. B.; Abcha, N.; Mutabazi, I.

    2010-07-01

    Disorder in spiral pattern arising in the counter-rotating Couette-Taylor flow has been investigated. It was revealed that in a certain range of flow control parameters, defects may be generated on the background of spirals periodically in time. Spatio-temporal structure of a single defect has been investigated in detail. A simple theoretical model based on asymptotic solution of the complex Ginzburg-Landau equation was proposed to explain characteristics of a defect. We found that, for a given super-criticality, defects appear at a definite value of the spiral wave phase.

  9. Temporal evolution of the chemical structure during the pattern transfer by ion-beam sputtering

    NASA Astrophysics Data System (ADS)

    Ha, N.-B.; Jeong, S.; Yu, S.; Ihm, H.-I.; Kim, J.-S.

    2015-01-01

    Ru films patterned by ion-beam sputtering (IBS) serve as sacrificial masks for the transfer of the patterns to Si(1 0 0) and metallic glass substrates by continued IBS. Under the same sputter condition, however, both bare substrates remain featureless. Chemical analyses of the individual nano structures simultaneously with the investigation of their morphological evolution reveal that the pattern transfer, despite its apparent success, suffers from premature degradation before the mask is fully removed by IBS. Moreover, the residue of the mask or Ru atoms stubbornly remains near the surface, resulting in unintended doping or alloying of both patterned substrates.

  10. Evaluating patterns of temporal glacier changes in Greater Himalayan Range, Jammu & Kashmir, India

    Microsoft Academic Search

    Arvind C. Pandey; Swagata Ghosh; M. S. Nathawat

    2011-01-01

    To account for the variable response of the Himalayan glaciers towards climatic warming during the recent past, an attempt has been made in the present study to evaluate the changes in glacier area and shift in glacier snout position of selected glaciers in a part of the Greater Himalayan Range (GHR), Jammu & Kashmir (J&K), India. Multi-temporal satellite images of

  11. Biodiversity, productivity and the temporal stability of productivity: patterns and processes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Theory predicts that the temporal stability of productivity, measured as the ratio of the mean to the standard deviation of community biomass, increases with species richness and evenness. We used experimental species mixtures of grassland plants to test this hypothesis and identify the mechanisms i...

  12. TEMPORAL GENE INDUCTION PATTERNS IN SHEEPSHEAD MINNOWS EXPOSED TO 17-ESTRADIOL

    EPA Science Inventory

    Gene arrays provide a powerful method to examine changes in gene expression in fish due to chemical exposures in the environment. In this study, we expanded an existing gene array for sheepshead minnows (Cyprinodon variegatus) (SHM) and used it to examine temporal changes in gene...

  13. Temporal stability of soil water contents as affected by weather patterns: a simulation study.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Temporal stability of soil water content (TS SWC) is a natural phenomenon that recently attracts attention and finds multiple applications. Large variations in the interannual and interseasonal TS SWC have been encountered among locations studied by various authors. The objective of this work was ...

  14. SPATIAL-TEMPORAL PATTERN AND DRIVING FORCES OF LAND USE CHANGES IN XIAMEN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using the Landsat TM data of 1988, 1998 and 2001 respectively, this paper analyzes the spatial-temporal characteristics of land use changes during the 13 years from 1988 to 2001 in Xiamen, China. The purpose of the research is to analyze the dynamic process of land use and land cover changes in orde...

  15. SPATIAL AND TEMPORAL PATTERNS IN MERCURY CONTAMINATION IN SEDIMENTS OF THE LAURENTIAL GREAT LAKES

    EPA Science Inventory

    Data from recent sediment surveys have been collated and mapped in order to determine the spatial distribution of mercury in sediments across the entire Great Lakes basin. Information from historical surveys has also been collated in order to evaluate temporal trends. Lake Huron ...

  16. Habitat overlap of enemies: temporal patterns and the role of spatial complexity

    Microsoft Academic Search

    Stephanie E. Hampton

    2004-01-01

    Environmental heterogeneity can promote coexistence of conflicting species by providing spatial or temporal refuges from strong interactions (e.g., intraguild predation, competition). However, in many systems, refuge availability and effectiveness may change through time and space because of variability in habitat use by either species. Here I consider how the intensity of intraguild predation risk varies from day to night for

  17. Urbanization and spatio-temporal patterns of flowering phenology of plants in the Phoenix metropolitan area

    E-print Network

    Hall, Sharon J.

    /Cercidium) and one non-indigenous plant (Nerium oleander) Chose sites from the 2000 CAP-LTER 200 point survey, mixed, and xeric), and (1) desert sites for Nerium 4-5 replicates for each Observe plants for first date in bloom, once a week for Nerium since it has a long blooming period Analyze intra-seasonal temporal

  18. Temporal patterns of orchid mycorrhizal fungi in meadows and forests as revealed by 454 pyrosequencing.

    PubMed

    Oja, Jane; Kohout, Petr; Tedersoo, Leho; Kull, Tiiu; Kõljalg, Urmas

    2015-03-01

    Orchid mycorrhizal (OrM) symbionts play a key role in the growth of orchids, but the temporal variation and habitat partitioning of these fungi in roots and soil remain unclear. Temporal changes in root and rhizosphere fungal communities of Cypripedium calceolus, Neottia ovata and Orchis militaris were studied in meadow and forest habitats over the vegetation period by using 454 pyrosequencing of the full internal transcribed spacer (ITS) region. The community of typical OrM symbionts differed by plant species and habitats. The root fungal community of N. ovata changed significantly in time, but this was not observed in C. calceolus and O. militaris. The rhizosphere community included a low proportion of OrM symbionts that exhibited a slight temporal turnover in meadow habitats but not in forests. Habitat differences in OrM and all fungal associates are largely attributable to the greater proportion of ectomycorrhizal fungi in forests. Temporal changes in OrM fungal communities in roots of certain species indicate selection of suitable fungal species by plants. It remains to be elucidated whether these shifts depend on functional differences inside roots, seasonality, climate or succession. PMID:25546739

  19. Disentangling temporal patterns in our perception of the fossil history of gymnosperms

    Microsoft Academic Search

    Borja Cascales-Miñana

    2012-01-01

    By taking gymnosperms as a case study, this article evaluates the perception of plant life history from the fossil record to test the biases associated with the time-dependent aspects of the taxonomy, following a stepwise modelling procedure based on two divergent sets of time units. The idea that the effects of the temporal component of paleobiological inference need to be

  20. Disentangling temporal patterns in our perception of the fossil history of gymnosperms

    Microsoft Academic Search

    Borja Cascales-Miñana

    2011-01-01

    By taking gymnosperms as a case study, this article evaluates the perception of plant life history from the fossil record to test the biases associated with the time-dependent aspects of the taxonomy, following a stepwise modelling procedure based on two divergent sets of time units. The idea that the effects of the temporal component of paleobiological inference need to be

  1. Spatial and temporal patterns of species diversity in montane mammal communities of western North America

    Microsoft Academic Search

    Elizabeth A. Hadly; Brian A. Maurer

    1996-01-01

    We present the results of the first analysis of distributional patterns of the same taxa across thousands of kilometres and thousands of years, which demonstrate that the exponents for the power relationships in space and time are similar. In both space and time, the distribution of mammalian taxa of the Great Basin and Rocky Mountains follows a 'nested subset' pattern.

  2. Spatial and temporal patterns of bovine anaplasmosis as reported by Illinois veterinarians

    Microsoft Academic Search

    L. L. Hungerford; R. D. Smith

    1996-01-01

    Spatial analysis was used in combination with more traditional epidemiologic methods to study patterns of anaplasmosis in a transitional area between anaplasmosis endemic and non-endemic regions. Data were collected using a mail survey from 179 veterinarians with practice areas including 100102 Illinois counties. The pattern of anaplasmosis reported by practitioners did not follow the general distribution of cattle and was

  3. Complex temporal and spatial patterns in nonequilibrium processes. Progress report, December 1, 1987--November 30, 1992

    SciTech Connect

    Swinney, H.L.

    1992-10-01

    We have used dynamical systems methods to study and characterize bifurcations and pattern formation in a variety of nonequilibrium systems. In this paper we describe our work on dynamical systems, chemical oscillations and chaos, chemical spatial patterns, instabilities in fluid dynamics, electrodeposition clusters, the ballast resistor, and crack propagation.

  4. Temporal consistency in the spatial pattern of seed predation across a forest - old field edge

    Microsoft Academic Search

    Scott J. Meiners; Kathleen LoGiudice

    2003-01-01

    Seed predation is an important factor in determining the rate of tree establishment in abandoned agricultural land. Edges, through altered habitat use by small mammals, may influence the spatial pattern of forest regenera- tion in these successional sites. To determine the spatial pattern of seed predation across a forest-old field edge, we used a grid that began 30 m inside

  5. Temporal consistency in the spatial pattern of seed predation across a forest – old field edge

    Microsoft Academic Search

    Scott J. Meiners; Kathleen LoGiudice

    2003-01-01

    Seed predation is an important factor in determining the rate of tree establishment in abandoned agricultural land. Edges, through altered habitat use by small mammals, may influence the spatial pattern of forest regeneration in these successional sites. To determine the spatial pattern of seed predation across a forest-old field edge, we used a grid that began 30 m inside the

  6. A cross-ecosystem comparison of spatial and temporal patterns of covariation in the recruitment of functionally analogous fish stocks

    NASA Astrophysics Data System (ADS)

    Megrey, Bernard A.; Hare, Jonathan A.; Stockhausen, William T.; Dommasnes, Are; Gjøsæter, Harald; Overholtz, William; Gaichas, Sarah; Skaret, Georg; Falk-Petersen, Jannike; Link, Jason S.; Friedland, Kevin D.

    2009-04-01

    Temporal and spatial patterns of recruitment ( R) and spawning stock biomass ( S) variability were compared among functionally analogous species and similar feeding guilds from six marine ecosystems. Data were aggregated into four regions including the Gulf of Maine/Georges Bank, the Norwegian/Barents Seas, the eastern Bering Sea, and the Gulf of Alaska. Variability was characterized by calculating coefficients of variation and anomalies for three response variables: ln( R), ln( R/ S), and stock-recruit model residuals. Patterns of synchrony and asynchrony in the response variables were examined among and between ecosystems, between- and within-ocean basins and among functionally analogous species groups using pair-wise correlation analysis corrected for within-time series autocorrelation, multivariate cross-correlation analyses and regime shift detectors. Time series trends in response variables showed consistent within basin similarities and consistent and coherent differences between the Atlantic and Pacific basin ecosystems. Regime shift detection algorithms identified two broad-scale regime shift time periods for the pelagic feeding guild (1972-1976 and 1999-2002) and possibly one for the benthic feeding guild (1999-2002). No spatial patterns in response variable coefficients of variation were observed. Results from multivariate cross-correlation analysis showed similar trends. The data suggest common external factors act in synchrony on stocks within ocean basins but temporal stock patterns, often of the same species or functional group, between basins change in opposition to each other. Basin-scale results (similar within but different between) suggest that the two geographically broad areas are connected by unknown mechanisms that, depending on the year, may influence the two basins in opposite ways. This work demonstrates that commonalities and synchronies in recruitment fluctuations can be found across geographically distant ecosystems but biophysical causes of the fluctuations remain difficult to identify.

  7. Spatial and temporal patterns of cuttlefish (Sepia officinalis) abundance and environmental influences – a case study using trawl fishery data in French Atlantic coastal, English Channel, and adjacent waters

    Microsoft Academic Search

    Jianjun Wang; Graham J. Pierce; Peter R. Boyle; Vincent Denis; Jean-paul Robin; Jose M. Bellido

    2003-01-01

    The spatial and temporal distribution patterns of cuttlefish abundance and the relationships between cuttlefish abundance and environmental variables in the French Atlantic coast, the English Channel, and adjacent waters were studied using both geographical information system and statistical methods. Cuttlefish have a clear general annual migration pattern, consistently occurring in broadly the same areas in different years. The strength of

  8. Evaluation of spatial and temporal patterns of insect damage and aflatoxin level in the pre-harvest corn fields to improve management tactics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatial and temporal patterns of insect damage in relation to aflatoxin contamination in a corn field with plants of uniform genetic background are not well understood. After previous examination of spatial patterns of insect damage and aflatoxin in pre-harvest corn fields, we examined spatial and ...

  9. Complex temporal patterns in molecular dynamics: A direct measure of the phase-space exploration by the trajectory at macroscopic time scales

    E-print Network

    Nerukh, Dmitry

    Complex temporal patterns in molecular dynamics: A direct measure of the phase-space exploration how the trajectory explores the phase space and independent from the particular molecular signal used in liquids form complex patterns in the phase space. Because of the system's high dimensionality defined

  10. Acoustic Differences In The Imitation Of Prosodic Patterns In Children With Autism Spectrum Disorders

    PubMed Central

    Diehl, Joshua John; Paul, Rhea

    2011-01-01

    In research, it has been difficult to characterize the prosodic production differences that have been observed clinically in Autism Spectrum Disorders (ASD). Moreover, the nature of these differences has been particularly hard to identify. This study examined one possible contributor to these perceived differences: motor planning. We examined the ability of children and adolescents with ASD to imitate prosodic patterns in comparison to a group with learning disabilities (LD) and a typically-developing (TD) comparison group. Overall, we found that both the ASD and LD groups were significantly worse at perceiving and imitating prosodic patterns than the TD comparison group. Similar to previous studies using non-imitative speech, participants with ASD showed a significantly longer duration of utterances than the two comparison groups when attempting to imitate an intonation pattern. The implications of differences in duration of utterances are discussed. This study also highlights the importance of using clinical comparison groups in studies of language performance in individuals with ASD. PMID:22125576

  11. Spatial and temporal patterns in Cimex lectularius (Hemiptera: Cimicidae) reporting in Philadelphia, PA.

    PubMed

    Mabud, Tarub S; Barbarin, Alexis M; Barbu, Corentin M; Levy, Katelyn H; Edinger, Jason; Levy, Michael Z

    2014-01-01

    We analyzed a comprehensive telephone log of pest infestation reports to assess the spatial and temporal trends in Cimex lectularius L. (bed bug) reporting throughout Philadelphia, PA. Citywide spatial analyses of reports from September 2011 to June 2012 revealed several statistically significant bed bug hotspots. However, these were small and diffuse. Temporal analyses of reports from December 2008 to May 2011 detected prominent seasonality in bed bug reporting, peaking in August and reaching a nadir in February each year. Controlling for seasonal cycling, the number of bed bug reports in Philadelphia increased steadily at a rate of approximately 4.5% per month (or 69.45% per year) from December 2008 to May 2011. While it may be difficult to spatially target citywide bed bug control measures because of the insects' widespread migration, interventions informed by seasonal trends may enhance efforts to curb the recent increases in urban bed bug populations. PMID:24605452

  12. Spatial and Temporal Patterns in Cimex lectularius (Hemiptera: Cimicidae) Reporting in Philadelphia, PA

    PubMed Central

    MABUD, TARUB S.; BARBARIN, ALEXIS M.; BARBU, CORENTIN M.; LEVY, KATELYN H.; EDINGER, JASON; LEVY, MICHAEL Z.

    2014-01-01

    We analyzed a comprehensive telephone log of pest infestation reports to assess the spatial and temporal trends in Cimex lectularius L. (bed bug) reporting throughout Philadelphia, PA. Citywide spatial analyses of reports from September 2011 to June 2012 revealed several statistically significant bed bug hotspots. However, these were small and diffuse. Temporal analyses of reports from December 2008 to May 2011 detected prominent seasonality in bed bug reporting, peaking in August and reaching a nadir in February each year. Controlling for seasonal cycling, the number of bed bug reports in Philadelphia increased steadily at a rate of ?4.5% per month (or 69.45% per year) from December 2008 to May 2011. While it may be difficult to spatially target citywide bed bug control measures because of the insects’ widespread migration, interventions informed by seasonal trends may enhance efforts to curb the recent increases in urban bed bug populations. PMID:24605452

  13. Spatio-temporal pattern of viral meningitis in Michigan, 1993-2001

    NASA Astrophysics Data System (ADS)

    Greene, Sharon K.; Schmidt, Mark A.; Stobierski, Mary Grace; Wilson, Mark L.

    2005-05-01

    To characterize Michigan's high viral meningitis incidence rates, 8,803 cases from 1993-2001 were analyzed for standard epidemiological indices, geographic distribution, and spatio-temporal clusters. Blacks and infants were found to be high-risk groups. Annual seasonality and interannual variability in epidemic magnitude were apparent. Cases were concentrated in southern Michigan, and cumulative incidence was correlated with population density at the county level (r=0.45, p<0.001). Kulldorff's Scan test identified the occurrence of spatio-temporal clusters in Lower Michigan during July-October 1998 and 2001 (p=0.01). More extensive data on cases, laboratory isolates, sociodemographics, and environmental exposures should improve detection and enhance the effectiveness of a Space-Time Information System aimed at prevention.

  14. Stimulus features underlying reduced tremor suppression with temporally patterned deep brain stimulation

    PubMed Central

    Birdno, Merrill J.; Kuncel, Alexis M.; Dorval, Alan D.; Turner, Dennis A.; Gross, Robert E.

    2012-01-01

    Deep brain stimulation (DBS) provides dramatic tremor relief when delivered at high-stimulation frequencies (more than ?100 Hz), but its mechanisms of action are not well-understood. Previous studies indicate that high-frequency stimulation is less effective when the stimulation train is temporally irregular. The purpose of this study was to determine the specific characteristics of temporally irregular stimulus trains that reduce their effectiveness: long pauses, bursts, or irregularity per se. We isolated these characteristics in stimulus trains and conducted intraoperative measurements of postural tremor in eight volunteers. Tremor varied significantly across stimulus conditions (P < 0.015), and stimulus trains with pauses were significantly less effective than stimulus trains without (P < 0.002). There were no significant differences in tremor between trains with or without bursts or between trains that were irregular or periodic. Thus the decreased effectiveness of temporally irregular DBS trains is due to long pauses in the stimulus trains, not the degree of temporal irregularity alone. We also conducted computer simulations of neuronal responses to the experimental stimulus trains using a biophysical model of the thalamic network. Trains that suppressed tremor in volunteers also suppressed fluctuations in thalamic transmembrane potential at the frequency associated with cerebellar burst-driver inputs. Clinical and computational findings indicate that DBS suppresses tremor by masking burst-driver inputs to the thalamus and that pauses in stimulation prevent such masking. Although stimulation of other anatomic targets may provide tremor suppression, we propose that the most relevant neuronal targets for effective tremor suppression are the afferent cerebellar fibers that terminate in the thalamus. PMID:21994263

  15. Spatial Patterns and Temporal Trajectories of the Bog Ground Layer Along a Post-Fire Chronosequence

    Microsoft Academic Search

    Brian W. Benscoter; Dale H. Vitt

    2008-01-01

    Peatland ground layer species composition is intricately tied to ecosystem function (for example, carbon storage). As the\\u000a primary disturbance in boreal bogs, wildfire selectively removes the ground layer vegetation, creating heterogeneous habitat\\u000a conditions and initiating succession. However, the successional trajectory of the ground layer community following fire is\\u000a poorly understood. Here we assess spatial and temporal changes in community composition

  16. Computational intelligence in biomedical imaging: multidimensional analysis of spatio-temporal patterns

    Microsoft Academic Search

    Axel Wismüller

    2011-01-01

    Technical innovations in radiology, such as advanced cross-sectional imaging methods, have opened up new vistas for the exploration\\u000a of structure and function of the human body enabling both high spatial and temporal resolution. However, these techniques\\u000a have led to vast amounts of data whose precise and reliable visual analysis by radiologists requires a considerable amount\\u000a of human intervention and expertise,

  17. Decoding temporal and spatial patterns of fault uplift using transient river long profiles

    Microsoft Academic Search

    Alexander C. Whittaker; Mikaël Attal; Patience A. Cowie; Gregory E. Tucker; Gerald Roberts

    2008-01-01

    We present detailed observations of rivers crossing active normal faults in the Central Apennines, Italy, where excellent constraints exist on the temporal and spatial history of fault movement. We demonstrate that rivers with drainage areas >10 km2 and crossing faults that have undergone an increase in throw rate within the last 1 My, have significant long-profile convexities. In contrast, channels that cross

  18. Spatial and temporal patterns in mercury contamination in sediments of the Laurentian Great Lakes

    Microsoft Academic Search

    Chris Marvin; Scott Painter; Ronald Rossmann

    2004-01-01

    Data from recent sediment surveys have been collated and mapped in order to determine the spatial distribution of mercury in sediments across the entire Great Lakes basin. Information from historical surveys has also been collated in order to evaluate temporal trends. Lake Huron (2002) exhibited the lowest mercury concentrations (lakewide average concentration, 0.043?g\\/g); Lakes Michigan (1994–1996) and Superior (2000) also

  19. Spatial and temporal patterns of soil respiration over the Japanese Archipelago: a model intercomparison study

    Microsoft Academic Search

    Akihiko Ito; Kazuhito Ichii; Tomomichi Kato

    2010-01-01

    We used terrestrial ecosystem models to estimate spatial and temporal variability in and uncertainty of estimated soil carbon\\u000a dioxide (CO2) efflux, or soil respiration, over the Japanese Archipelago. We compared five carbon-cycle models to assess inter-model variability:\\u000a Biome-BGC, CASA, LPJ, SEIB, and VISIT. These models differ in approaches to soil carbon dynamics, root respiration estimation,\\u000a and relationships between decomposition and

  20. Two distinct modes of forebrain circuit dynamics underlie temporal patterning in the vocalizations of young songbirds

    PubMed Central

    Aronov, Dmitriy; Veit, Lena; Goldberg, Jesse H.; Fee, Michale S.

    2011-01-01

    Accurate timing is a critical aspect of motor control, yet the temporal structure of many mature behaviors emerges during learning from highly variable exploratory actions. How does a developing brain acquire the precise control of timing in behavioral sequences? To investigate the development of timing, we analyzed the songs of young juvenile zebra finches. These highly variable vocalizations, akin to human babbling, gradually develop into temporally-stereotyped adult songs. We find that the durations of syllables and silences in juvenile singing are formed by a mixture of two distinct modes of timing – a random mode producing broadly-distributed durations early in development, and a stereotyped mode underlying the gradual emergence of stereotyped durations. Using lesions, inactivations, and localized brain cooling we investigated the roles of neural dynamics within two premotor cortical areas in the production of these temporal modes. We find that LMAN (lateral magnocellular nucleus of the nidopallium) is required specifically for the generation of the random mode of timing, and that mild cooling of LMAN causes an increase in the durations produced by this mode. On the contrary, HVC (used as a proper name) is required specifically for producing the stereotyped mode of timing, and its cooling causes a slowing of all stereotyped components. These results show that two neural pathways contribute to the timing of juvenile songs, and suggest an interesting organization in the forebrain, whereby different brain areas are specialized for the production of distinct forms of neural dynamics. PMID:22072687

  1. Species differences in the temporal pattern of Drosophila urate oxidase gene expression are attributed to trans-acting regulatory changes.

    PubMed Central

    Wallrath, L L; Friedman, T B

    1991-01-01

    The Drosophila melanogaster urate oxidase (UO)-encoding gene is expressed in the third-instar larva and adult. In contrast, the Drosophila pseudoobscura UO gene is only expressed in the adult, whereas the Drosophila virilis UO gene is expressed only in the third-instar larva. UO activity in these three Drosophila species is detected exclusively within the Malpighian tubules. By using P-element mediated germ-line transformation, UO genes from D. pseudoobscura and D. virilis were integrated into the D. melanogaster genome. The D. virilis and D. pseudoobscura UO transgenes were expressed in the third-instar larva and adult Malpighian tubules, which is the D. melanogaster temporal pattern of UO gene expression. These observations indicate that differences in the temporal patterns of regulation of UO genes among these three Drosophila species are not likely to be due to evolutionary changes in the sequence or complement of UO cis-acting regulatory elements. The species differences in UO regulation are probably the result of changes in one or more trans-acting factors required for UO gene expression in the third-instar larval and adult stages. Images PMID:2062830

  2. Temporal and spatial distribution patterns of heavy metals in soil at a long-standing sewage farm.

    PubMed

    Li, P J; Stagnitti, F; Xiong, X; Peterson, J

    2009-02-01

    Australia's oldest sewage farm in Werribee, Victoria is a significant public asset with more than 110 years of history and it now treats half of Melbourne's municipal sewage. Currently three parallel methods, i.e. lagoon, land filtration and grass filtration were used to treat raw sewage from Melbourne. The land filtration area is soil-pasture-cattle complex system and it operates on 3,633 ha of permanent pastures for livestock grazing. The land filtration area by intermittent irrigation of sewage occurs during the months of high evaporation from October to April. The monitoring study was aimed to find out the temporal and spatial distribution patterns of heavy metals in the soil at land filtration area in the long standing sewage farm. The monitoring results show that the temporal distribution patterns of Cd, Cr, Cu, Ni, Pb and Zn follow the exponential regression equations in soil layer 0-20 cm and the linear equations in soil layer 20-40 cm respectively. The accumulated concentrations of heavy metals in the soils are high enough for the land to be considered contaminated. The exponential trend of heavy metal of soil in land filtration area should be controlled immediately by soil remediation or by change of treatment process of flow configuration. PMID:18288581

  3. Remating by female Mediterranean fruit flies (Ceratitis capitata, Diptera: Tephritidae): temporal patterns and modulation by male condition.

    PubMed

    Gavriel, Sagi; Gazit, Yoav; Yuval, Boaz

    2009-07-01

    We determined the temporal pattern of female remating in the Mediterranean fruit fly, Ceratitis capitata, and how mating with sterile males affects remating. In addition, we examined the hypotheses that sterile male nutrition and age affect the subsequent receptivity of their mates. Temporally, female receptivity varied significantly throughout the experimental period. Relatively high levels of remating (14%) on the days following the first copulation were followed by a decline, with a significantly low point (4.1%) 2 weeks after mating. Subsequently, receptivity is gradually restored (18%) 3 and 4 weeks after the initial copulation. When females were first mated to sterile males, significantly higher remating percentages were recorded. The ability of sterile males to inhibit receptivity of both wild and laboratory reared females on the day of first mating was significantly improved when they were fed a nutrient rich diet. Male age at first mating also affected female receptivity: sterile males of intermediate age (11 days old) inhibited female remating significantly more than younger or older flies. Although further studies are needed to determine the relative roles of natural and sexual selection in modulating patterns of female sexual receptivity, the Sterile Insect Technique may be improved by releasing well nourished, older sterile males. PMID:19482138

  4. Spatial pattern of soil moisture and its temporal stability within profiles on a loessial slope in northwestern China

    NASA Astrophysics Data System (ADS)

    Jia, Yu-Hua; Shao, Ming-An; Jia, Xiao-Xu

    2013-07-01

    Temporal stability of spatial distributions of soil moisture are usually observed after repeated surveys of soil moisture across an area. To understand how temporal stability of soil moisture varied with soil depth under the combined influences of vegetation and local topography, we collected soil moisture data at intervals of 10 cm within 1-m profiles on a loessial slope in China in four plots (61 m × 5 m) under different types of vegetation (Korshinsk peashrub, KOP; purple alfalfa, ALF; natural fallow, NAF; millet, MIL). Measurements of soil water content were made by neutron probes on 15 occasions between 2010 and 2012. Soil moisture distributions in both the vertical and horizontal dimensions were investigated to describe its spatial pattern and to lay the groundwork for better understanding its temporal stability characteristics. The results indicated that: (1) soil moisture presented different vertical but similar horizontal trends in the four plots, with significant correlations of soil moisture occurring primarily among adjacent soil layers irrespective of vegetation types, mostly in soil profiles under KOP and ALF and less frequently in soil profiles under NAF and MIL; (2) based on Spearman rank correlation coefficients, with increasing depth temporal stability generally increased under KOP and MIL, but first increased and then decreased under ALF, and increased after the first three measurements under NAF; (3) based on the relative difference technique, points with extreme moisture tended to remain representative at more depths than did points with average moisture and their time stability increased with increasing soil depth; and (4) the correlation between MRD (mean relative differences) and the wetness index weakened with soil depth. The relationship between SDRD (the standard deviation of MRD) and the wetness index varied nonlinearly with soil depth. Vegetation type, soil depth and the wetness index, in descending order of influence, had significant effects on the temporal stability of soil moisture. Among selected soil properties, saturated hydraulic conductivity, bulk density and soil organic carbon all significantly affected the SDRDs. These observations are expected to add valuable information to the theory of temporal stability and for the practices of soil moisture management.

  5. Characteristics of temporal patterns of cortisol and luteinizing hormone in primiparous, postpartum, anovular, suckled, beef cows exposed acutely to bulls

    PubMed Central

    2010-01-01

    Background The physiological mechanism by which bulls stimulate resumption of ovarian cycling activity in postpartum, anovular, suckled cows after calving may involve the concurrent activation of the hypothalamic-hypophyseal-ovarian (HPO) axis and hypothalamic-hypophyseal-adrenal (HPA) axis. Thus, the objectives of this experiment were to determine if characteristics of temporal patterns of cortisol and luteinizing hormone (LH) in postpartum, anovular, beef cows are influenced by acute exposure to bulls. The null hypotheses were that daily, temporal characteristics of cortisol and LH concentration patterns do not differ between cows exposed acutely to bulls or steers. Methods Sixteen cows were assigned randomly 67 +/- 4 (+/- SE) after calving to be exposed to bulls (EB, n = 8) or steers (ES, n = 8) 5 h daily for 9 d (D 0 to 8). Blood samples were collected daily from each cow via jugular catheters at 15-min intervals for 6 h from 1000 to 1600 h each day. The 5-h exposure period began 1 h after the start of the intensive bleeding period. Characteristics of cortisol and LH concentration patterns (mean, baseline, pulse frequency, pulse amplitude, and pulse duration) were identified by PULSAR analyses. Results Mean cortisol concentrations decreased (P < 0.05) in cows in both treatments from D 0 to D 2. Thereafter, mean cortisol concentrations stabilized and did not differ (P > 0.10) between EB and ES cows. The decrease in mean cortisol concentrations in EB and ES cows from D 0 to D 2 was attributed to cows acclimatizing to intensive blood sampling and handling procedures. Consequently, analyses for characteristics of cortisol and LH concentration patterns included D 2 through 8 only. Cortisol mean and baseline concentrations, and pulse amplitude did not differ (P > 0.10) between EB and ES cows. However, cortisol pulse duration tended to be longer (P = 0.09) and pulse frequency was lower (P = 0.05) in EB than ES cows. LH pulse frequency was greater (P = 0.06) in EB than ES cows. All other characteristics of LH concentration patterns did not differ (P > 0.10) between EB and ES cows. Characteristics of cortisol concentration patterns were not related to characteristics of LH concentration patterns for ES cows (P > 0.10). However, as cortisol pulse amplitude increased, LH pulse amplitude decreased (b1 = -0.04; P < 0.05) for EB cows. Conclusions In conclusion, exposing primiparous, postpartum, anovular, suckled cows to bulls for 5-h daily over a 9-d period did not alter mean concentrations of cortisol or LH compared to mean concentrations of cortisol and LH in cows exposed to steers. However, exposing cows to bull in this manner altered characteristics of temporal patterns of both LH and cortisol by increasing LH pulse frequency and decreasing cortisol pulse frequency. Interestingly, in cows exposed to bulls, as amplitude and frequency of cortisol pulses decreased, amplitudes of LH pulses increased and frequency of LH pulses tended to increase. Thus, the physiological mechanism of the biostimulatory effect of bulls may initially involve modification of the HPA axis and these changes may facilitate activation of the HPO axis and resumption of ovulatory cycles in postpartum, anovular, suckled cows. PMID:20642864

  6. Spatio-temporal malaria transmission patterns in Navrongo demographic surveillance site, northern Ghana

    PubMed Central

    2013-01-01

    Background The relationship between entomological measures of malaria transmission intensity and mortality remains uncertain. This is partly because transmission is heterogeneous even within small geographical areas. Studying this relationship requires high resolution, spatially structured, longitudinal entomological data. Geostatistical models that have been used to analyse the spatio-temporal heterogeneity have not considered the uncertainty in both sporozoite rate (SR) and mosquito density data. This study analysed data from Kassena-Nankana districts in northern Ghana to obtain small area estimates of malaria transmission rates allowing for this uncertainty. Methods Independent Bayesian geostatistical models for sporozoite rate and mosquito density were fitted to produce explicit entomological inoculation rate (EIR) estimates for small areas and short time periods, controlling for environmental factors. Results Mosquitoes were trapped from 2,803 unique locations for three years using mainly CDC light traps. Anopheles gambiae constituted 52%, the rest were Anopheles funestus. Mean biting rates for An. funestus and An. gambiae were 32 and 33 respectively. Most bites occurred in September, the wettest month. The sporozoite rates were higher in the dry periods of the last two years compared with the wet period. The annual EIR varied from 1,132 to 157 infective bites. Monthly EIR varied between zero and 388 infective bites. Spatial correlation for SR was lower than that of mosquito densities. Conclusion This study confirms the presence of spatio-temporal heterogeneity in malaria transmission within a small geographical area. Spatial variance was stronger than temporal especially in the SR. The estimated EIR will be used in mortality analysis for the area. PMID:23405912

  7. Factors controlling the long-term temporal and spatial patterns of nitrate-nitrogen export in a dairy farming watershed.

    PubMed

    Jiang, Rui; Wang, Chun-Ying; Hatano, Ryusuke; Kuramochi, Kanta; Hayakawa, Atsushi; Woli, Krishna P

    2015-04-01

    It is difficult to investigate the factors that control the riverine nitrate-nitrogen (NO3 (-)-N) export in a watershed which gains or losses groundwater. To control the NO3 (-)-N contamination in these watersheds, it is necessary to investigate the factors that are related to the export of NO3 (-)-N that is only produced by the watershed itself. This study was conducted in the Shibetsu watershed located in eastern Hokkaido, Japan, which gains external groundwater contribution (EXT) and 34 % of the annual NO3 (-)-N loading occurs through EXT. The riverine NO3 (-)-N exports from 1980 to 2009 were simulated by the SWAT model, and the factors controlling the temporal and spatial patterns of NO3 (-)-N exports were investigated without considering the EXT. The results show that hydrological events control NO3 (-)-N export at the seasonal scale, while the hydrological and biogeochemical processes are likely to control NO3 (-)-N export at the annual scale. There was an integrated effect among the land use, topography, and soil type related to denitrification process, that regulated the spatial patterns of NO3 (-)-N export. The spatial distribution of NO3 (-)-N export from hydrologic response units (HRUs) identified the agricultural areas with surplus N that are vulnerable to nitrate contamination. A new standard for the N fertilizer application rate including manure application should be given to control riverine NO3 (-)-N export. This study demonstrates that applying the SWAT model is an appropriate method to determine the temporal and spatial patterns of NO3 (-)-N export from the watershed which includes EXT and to identify the crucial pollution areas within a watershed in which the management practices can be improved to more effectively control NO3 (-)-N export to water bodies. PMID:25805369

  8. Spatial and temporal patterns of carabid activity-density in cereals do not explain levels of predation on weed seeds.

    PubMed

    Saska, P; van der Werf, W; de Vries, E; Westerman, P R

    2008-04-01

    Seed predation is an important component of seed mortality of weeds in agro-ecosystems, but the agronomic use and management of this natural weed suppression is hampered by a lack of insight in the underlying ecological processes. In this paper, we investigate whether and how spatial and temporal variation in activity-density of granivorous ground beetles (Coleoptera: Carabidae) results in a corresponding pattern of seed predation. Activity-density of carabids was measured by using pitfall traps in two organic winter wheat fields from March to July 2004. Predation of seeds (Capsella bursa-pastoris, Lamium amplexicaule, Poa annua and Stellaria media) was assessed using seed cards at the same sites and times. As measured by pitfall traps, carabids were the dominant group of insects that had access to the seed cards. In the field, predation of the four different species of seed was in the order: C. bursa-pastoris>P. annua>S. media>L. amplexicaule; and this order of preference was confirmed in the laboratory using the dominant species of carabid. On average, seed predation was higher in the field interior compared to the edge, whereas catches of carabids were highest near the edge. Weeks with elevated seed predation did not concur with high activity-density of carabids. Thus, patterns of spatial and temporal variation in seed predation were not matched by similar patterns in the abundance of granivorous carabid beetles. The lack of correspondence is ascribed to effects of confounding factors, such as weather, the background density of seeds, the composition of the carabid community, and the phenology and physiological state of the beetles. Our results show that differences in seed loss among weed species may be predicted from laboratory trials on preference. However, predator activity-density, as measured in pitfall traps, is an insufficient predictor of seed predation over time and space within a field. PMID:18076785

  9. Acoustic Analyses and Intelligibility Assessments of Timing Patterns Among Chinese English Learners with Different Dialect Backgrounds.

    PubMed

    Chen, Hsueh Chu

    2014-09-01

    This paper includes two interrelated studies. The first production study investigates the timing patterns of English as spoken by Chinese learners with different dialect backgrounds. The second comprehension study explores native and non-native speakers' assessments of the intelligibility of Chinese-accented English, and examines the effects of the listeners' language backgrounds on their perceptions of Chinese-accented English. The results showed that the Hong Kong (HK) group performed better in unstressed syllable duration compared with the Taiwan (TW) and Beijing (BJ) groups. The results also revealed that all six listener groups achieved at least 78 % intelligibility, with the native speaker accent achieving the highest rating, followed by the HK, TW, and BJ accents. A shared first language (L1) background may have little or no impact on intelligibility. The speech properties might prevail over the shared L1 effect. All listeners perceived inappropriate word-stress shift and consonant cluster simplifications to be the most unintelligible features. PMID:25194949

  10. A smart sensor system for trace organic vapor detection using a temperature-controlled array of surface acoustic wave vapor sensors, automated preconcentrator tubes, and pattern recognition

    SciTech Connect

    Grate, J.W. [Pacific Northwest Lab., Richland, WA (United States); Rose-Pehrsson, S.L. [Naval Research Lab., Washington, DC (United States). Chemistry Div.; Klusty, M.; Wohltjen, H. [Microsensor Systems, Inc., Bowling Green, KY (United States)

    1993-05-01

    A smart sensor system for the detection, of toxic organophosphorus and toxic organosulfur vapors at trace concentrations has been designed, fabricated, and tested against a wide variety of vapor challenges. The key features of the system are: An array of four surface acoustic wave (SAW) vapor sensors, temperature control of the vapor sensors, the use of pattern recognition to analyze the sensor data, and an automated sampling system including thermally-desorbed preconcentrator tubes (PCTs).

  11. First results on forecasting the spatial occurrence pattern of L-band scintillation and its temporal evolution

    NASA Astrophysics Data System (ADS)

    Sridharan, R.; Bagiya, Mala S.; Sunda, Surendra; Choudhary, Rajkumar; Pant, Tarun K.; Jose, Lijo

    2014-11-01

    After a fairly successful attempt to forecast the temporal evolution of L-band scintillation over a given location, Trivandrum (8.5° N, 76.91° E, dip latitude 0.5° N) (Sridharan et al., 2012, J. Atmos. Sol. Terr. Phys. 80 230-238; Bagiya et al., 2014, J. Atmos. Sol. Terr. Phys. 110-111, 15-22), an attempt has been made here to generate the spatial-temporal maps of the occurrence pattern of L-band scintillation over the Indian region. To start with, the day time fluctuations in [f0F2]2 are used to forecast the temporal evolution of perturbations during the course of the night over Trivandrum. Similar to the earlier studies, here too it is taken that the electron density perturbations retain their characteristics throughout night and traverse with a uniform velocity. This implies that when the integrity of wave train of electron density perturbations is retained, any particular feature that passes over Trivandrum would have crossed over another location west of Trivandrum at an earlier time only dictated by the zonal velocity. With this assumption it becomes feasible to generate the probable spatial and temporal pattern of L-band scintillation. The consequences/limitations of the above assumptions are discussed in detail. The observed relation between the total duration of spread-F and the base height of the F-region (h'F) at 1930 LT has been explained in terms of the favourable background neutral atmospheric conditions. Following Bagiya et al. (2013, J. Geophys. Res. 118, 1-8), the relation between h'F at 1930 LT and the probable maximum latitudinal extent of the spread-F enables specification of the upper limit for the latitudes likely to be affected by the scintillation. It is believed that the presented results hold enough potential to generate the reliable L-band scintillation forecast maps and provide the necessary alerts to the satellite based air navigation users.

  12. Decoupled temporal patterns of evolution and ecology in two post-Paleozoic clades

    NASA Technical Reports Server (NTRS)

    McKinney, F. K.; Lidgard, S.; Sepkoski, J. J. Jr; Taylor, P. D.

    1998-01-01

    Counts of taxonomic diversity are the prevailing standards for documenting large-scale patterns of evolution in the fossil record. However, the secular pattern of relative ecological importance between the bryozoan clades Cyclostomata and Cheilostomata is not reflected fully in compilations of generic diversity or within-fauna species richness, and the delayed ecological recovery of the Cheilostomata after the mass extinction at the Cretaceous-Tertiary boundary is missed entirely. These observations demonstrate that evolutionary success and ecological dominance can be decoupled and profoundly different, even over tens of millions of years.

  13. Temporal pattern of questing tick Ixodes ricinus density at differing elevations in the coastal region of western Norway

    PubMed Central

    2014-01-01

    Background Climate change can affect the activity and distribution of species, including pathogens and parasites. The densities and distribution range of the sheep tick (Ixodes ricinus) and it’s transmitted pathogens appears to be increasing. Thus, a better understanding of questing tick densities in relation to climate and weather conditions is urgently needed. The aim of this study was to test predictions regarding the temporal pattern of questing tick densities at two different elevations in Norway. We predict that questing tick densities will decrease with increasing elevations and increase with increasing temperatures, but predict that humidity levels will rarely affect ticks in this northern, coastal climate with high humidity. Methods We described the temporal pattern of questing tick densities at ~100 and ~400 m a.s.l. along twelve transects in the coastal region of Norway. We used the cloth lure method at 14-day intervals during the snow-free season to count ticks in two consecutive years in 20 m2 plots. We linked the temporal pattern of questing tick densities to local measurements of the prevailing weather. Results The questing tick densities were much higher and the season was longer at ~100 compared to at ~400 m a.s.l. There was a prominent spring peak in both years and a smaller autumn peak in one year at ~100 m a.s.l.; but no marked peak at ~400 m a.s.l. Tick densities correlated positively with temperature, from low densities <5°C, then increasing and levelling off >15-17°C. We found no evidence for reduced questing densities during the driest conditions measured. Conclusions Tick questing densities differed even locally linked to elevation (on the same hillside, a few kilometers apart). The tick densities were strongly hampered by low temperatures that limited the duration of the questing seasons, whereas the humidity appeared not to be a limiting factor under the humid conditions at our study site. We expect rising global temperatures to increase tick densities and lead to a transition from a short questing season with low densities in the current cold and sub-optimal tick habitats, to longer questing seasons with overall higher densities and a marked spring peak. PMID:24725997

  14. Spatio-temporal expression patterns of Arabidopsis thaliana and Medicago truncatula defensin-like genes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant genomes typically contain several hundred defensin-like (DEFL) genes that encode short proteins resembling defensins, which are antimicrobial polypeptides. Little is known about the expression patterns of DEFL genes because most were recently discovered and many are not well represented on sta...

  15. Spatial-Temporal Patterns of Retinal Waves Underlying Activity-Dependent Refinement of Retinofugal Projections

    PubMed Central

    Stafford, Ben K.; Sher, Alexander; Litke, Alan M.; Feldheim, David A.

    2009-01-01

    During development, retinal axons project coarsely within their central visual targets before refining to form precisely organized synaptic connections. Spontaneous retinal activity, in the form of acetylcholine-driven retinal waves, is widely proposed to be necessary for establishing these precise projection patterns. In particular, both axonal terminations of retinal ganglion cells (RGCs) and the size of receptive fields of neurons in visual areas of the brain are larger in mice that lack the ?2 subunit of the nicotinic acetylcholine receptor (?2KO). Here, using a large-scale, high-density multi-electrode array to record single-unit activity from hundreds of RGCs simultaneously, we present analysis of early post-natal retinal activity from both wild type (WT) and ?2KO retinas. We find that ?2KO retinas have correlated patterns of activity, but many aspects of these patterns differ from those of WT retina. Quantitative analysis of these differences suggests that wave directionality, coupled with short-distance correlated bursting patterns of RGCs, work together to drive refinement of retinofugal projections. PMID:19874788

  16. How Temporal and Spatial Aspects of Presenting Visualizations Affect Learning about Locomotion Patterns

    ERIC Educational Resources Information Center

    Imhof, Birgit; Scheiter, Katharina; Edelmann, Jorg; Gerjets, Peter

    2012-01-01

    Two studies investigated the effectiveness of dynamic and static visualizations for a perceptual learning task (locomotion pattern classification). In Study 1, seventy-five students viewed either dynamic, static-sequential, or static-simultaneous visualizations. For tasks of intermediate difficulty, dynamic visualizations led to better…

  17. Bioaccumulation Patterns and Temporal Trends of Mercury Exposure in Wisconsin Common Loons

    Microsoft Academic Search

    Brick M. Fevold; Michael W. Meyer; Paul W. Rasmussen; Stanley A. Temple

    2003-01-01

    A long term field study was initiated by the Wisconsin Department of Natural Resources in 1992 to elucidate patterns of common loon (Gavia immer) mercury (Hg) exposure. Analysis of loon blood and feather samples collected from recaptured adult loons in Wisconsin 1992–2000 found evidence of a decline in overall body burdens of mercury in common loons for this region. The

  18. Spatio-temporal patterns of soil water storage under dryland agriculture at the watershed scale

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil water patterns vary significantly due to precipitation, soil properties, topographic features, and land use. We used empirical orthogonal function (EOF) analysis to characterize the spatial variability of soil water across a 37-ha field of the Washington State University Cook Agronomy Farm near...

  19. Estimating spatio-temporal patterns of agricultural productivity in fragmented landscapes using AVHRR NDVI time series

    Microsoft Academic Search

    Michael J Hill; Graham E Donald

    2003-01-01

    The characteristics of Normalized Difference Vegetation Index (NDVI) time series can be disaggregated into a set of quantitative metrics that may be used to derive information about vegetation phenology and land cover. In this paper, we examine the patterns observed in metrics calculated for a time series of 8 years over the southwest of Western Australia—an important crop and animal

  20. Temporal pattern of erythropoietin titers in kidney tissue during hypoxic hypoxia

    Microsoft Academic Search

    Wolfgang Jelkmann

    1982-01-01

    Plasma titers of erythropoietin (Ep) are known to increase initially during hypoxia and to return then towards prehypoxia values. To find out if this pattern of plasma Ep might be related to changes in the production of the hormone, I have compared plasma with kidney Ep titers in hypoxic rats. Rats were exposed to hypoxia in a hypobaric chamber at

  1. Spatial and Temporal Patterns of Small-Scale Mixing in Drake Passage

    Microsoft Academic Search

    Andrew F. Thompson; Sarah T. Gille; J. A. MacKinnon; Janet Sprintall

    2007-01-01

    Temperature and salinity profiles obtained with expendable CTD probes throughout Drake Passage between February 2002 and July 2005 are analyzed to estimate turbulent diapycnal eddy diffusivities to a depth of 1000 m. Diffusivity values are inferred from density\\/temperature inversions and internal wave vertical strain. Both methods reveal the same pattern of spatial variability across Drake Passage; diffusivity estimates from inversions

  2. SPATIAL AND TEMPORAL PATTERNS OF MAIZE WEEVIL PRE-HARVEST INFESTATION IN CORN FIELDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three corn fields were sampled continuously for 6- or 8-wks to determine the invasion patterns of the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), infestation. The weekly samplings started when the kernel moisture level was about 30%. The weevil infestation levels vari...

  3. Multivariate pattern analysis of the human medial temporal lobe revealed representationally categorical cortex and representationally agnostic hippocampus

    PubMed Central

    Huffman, Derek J.; Stark, Craig E.L.

    2014-01-01

    Contemporary theories of the medial temporal lobe (MTL) suggest that there are functional differences between the MTL cortex and the hippocampus. High-resolution functional magnetic resonance imaging and multivariate pattern analysis were utilized to study whether MTL subregions could classify categories of images, with the hypothesis that the hippocampus would be less representationally categorical than the MTL cortex. Results revealed significant classification accuracy for faces versus objects and faces versus scenes in MTL cortical regions—parahippocampal cortex and perirhinal cortex—with little evidence for category discrimination in the hippocampus. MTL cortical regions showed significantly greater classification accuracy than the hippocampus. The hippocampus showed significant classification accuracy for images compared to a non-mnemonic baseline task, suggesting that it responded to the images. Classification accuracy in a region of interest encompassing retrosplenial cortex and the posterior cingulate cortex posterior to retrosplenial cortex (RSC/PCC), showed a similar pattern of results to parahippocampal cortex, supporting the hypothesis that these regions are functionally related. The results suggest that parahippocampal cortex, perirhinal cortex, and RSC/PCC are representationally categorical and the hippocampus is more representationally agnostic, which is concordant with the hypothesis of the role of the hippocampus in pattern separation. PMID:24976498

  4. Multivariate pattern analysis of the human medial temporal lobe revealed representationally categorical cortex and representationally agnostic hippocampus.

    PubMed

    Huffman, Derek J; Stark, Craig E L

    2014-11-01

    Contemporary theories of the medial temporal lobe (MTL) suggest that there are functional differences between the MTL cortex and the hippocampus. High-resolution functional magnetic resonance imaging and multivariate pattern analysis were utilized to study whether MTL subregions could classify categories of images, with the hypothesis that the hippocampus would be less representationally categorical than the MTL cortex. Results revealed significant classification accuracy for faces versus objects and faces versus scenes in MTL cortical regions-parahippocampal cortex (PHC) and perirhinal cortex (PRC)-with little evidence for category discrimination in the hippocampus. MTL cortical regions showed significantly greater classification accuracy than the hippocampus. The hippocampus showed significant classification accuracy for images compared to a nonmnemonic baseline task, suggesting that it responded to the images. Classification accuracy in a region of interest encompassing retrosplenial cortex (RSC) and the posterior cingulate cortex (PCC) posterior to RSC, showed a similar pattern of results to PHC, supporting the hypothesis that these regions are functionally related. The results suggest that PHC, PRC, and RSC/PCC are representationally categorical and the hippocampus is more representationally agnostic, which is concordant with the hypothesis of the role of the hippocampus in pattern separation. PMID:24976498

  5. Spatial-temporal change in precipitation patterns based on the cloud model across the Wei River Basin, China

    NASA Astrophysics Data System (ADS)

    Huang, Shengzhi; Hou, Beibei; Chang, Jianxia; Huang, Qiang; Chen, Yutong

    2014-05-01

    It is of significant importance to investigate the spatial-temporal change in precipitation patterns due to its great effects on droughts, floods, soil erosion and water resource management. A complete investigation of precipitation structure and its distribution pattern based on daily precipitation covering 1960-2005 at 21 meteorological stations in the Wei River Basin has been performed. In order to comprehensively and objectively describe the changing pattern of precipitation, the cloud model is employed to quantitatively analyse the average, uniformity and stability of precipitation. Results indicate the following: (1) the occurrence of different precipitation durations exhibits a positive exponential curve with the decrease in precipitation durations, and 1-3-day events are the predominant precipitation events which have an increasing trend; (2) precipitation and its non-uniformity is increasingly reducing, while its stability increases initially then decreases; (3) mean precipitation reduces from southeast to northwest, and the precipitation of the Guanzhong Plain has a low uniformity and stability due to its location and increasingly intensifying human activities. The cloud model provides a new idea and quantitative measure for the evaluation of the uniformity and stability of precipitation.

  6. Identification of Damaged Wheat Kernels and Cracked-Shell Hazelnuts with Impact Acoustics Time-Frequency Patterns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new adaptive time-frequency (t-f) analysis and classification procedure is applied to impact acoustic signals for detecting hazelnuts with cracked shells and three types of damaged wheat kernels. Kernels were dropped onto a steel plate, and the resulting impact acoustic signals were recorded with ...

  7. Statistical sensitivity for detection of spatial and temporal patterns in rodent population densities.

    PubMed Central

    Parmenter, C. A.; Yates, T. L.; Parmenter, R. R.; Dunnum, J. L.

    1999-01-01

    A long-term monitoring program begun 1 year after the epidemic of hantavirus pulmonary syndrome in the U.S. Southwest tracked rodent density changes through time and among sites and related these changes to hantavirus infection rates in various small-mammal reservoir species and human disease outbreaks. We assessed the statistical sensitivity of the program's field design and tested for potential biases in population estimates due to unintended deaths of rodents. Analyzing data from two sites in New Mexico from 1994 to 1998, we found that for many species of Peromyscus, Reithrodontomys, Neotoma, Dipodomys, and Perognathus, the monitoring program detected species-specific spatial and temporal differences in rodent densities; trap-related deaths did not significantly affect long-term population estimates. The program also detected a short-term increase in rodent densities in the winter of 1997-98, demonstrating its usefulness in identifying conditions conducive to increased risk for human disease. PMID:10081679

  8. Spatial and temporal patterns in water chemistry of two high elevation lakes in southeast Wyoming

    SciTech Connect

    Musselman, R.C. [Forest Service, Fort Collins, CO (United States). Rocky Mountain Forest and Range Experiment Station

    1995-12-31

    The Glacier Lakes Ecosystem Experiments Site (GLEES) was established to examine the effects of atmospheric deposition and climate change on alpine and subalpine ecosystems. This report documents temporal and spatial trends during 1993 in water chemistry in East and West Glacier Lakes. Data are presented on seasonal and lake depth changes in water chemistry of the two lakes. The application of the results to appropriate sampling protocols for two alpine lakes is discussed. Both lakes were sampled during the same day, at midday. Samples were kept cool, returned to the lab the same day, and filtered for analysis. Samples were analyzed for cations and anions, pH, and conductivity at the Rocky Mountain Station Water Chemistry laboratory. Silica and aluminum were also measured for some sample dates.

  9. Automatic Segmentation of Polypoidal Choroidal Vasculopathy from Indocyanine Green Angiography Using Spatial and Temporal Patterns

    PubMed Central

    Lin, Wei-Yang; Yang, Sheng-Chang; Chen, Shih-Jen; Tsai, Chia-Ling; Du, Shuo-Zhao; Lim, Tock-Han

    2015-01-01

    Purpose To develop a computer-aided diagnostic tool for automated detection and quantification of polypoidal regions in indocyanine green angiography (ICGA) images. Methods The ICGA sequences of 59 polypoidal choroidal vasculopathy (PCV) treatment–naïve patients from five Asian countries (Hong Kong, Singapore, South Korea, Taiwan, and Thailand) were provided by the EVEREST study. The ground truth was provided by the reading center for the presence of polypoidal regions. The proposed detection algorithm used both temporal and spatial features to characterize the severity of polypoidal lesions in ICGA sequences. Leave-one-out cross validation was carried out so that each patient was used once as the validation sample. For each patient, a fixed detection threshold of 0.5 on the severity was applied to obtain sensitivity, specificity, and balanced accuracy with respect to the ground truth. Results Our system achieved an average accuracy of 0.9126 (sensitivity = 0.9125, specificity = 0.9127) for detection of polyps in the 59 ICGA sequences. Among the total of 222 features extracted from ICGA sequence, the spatial variances exhibited best discriminative power in distinguishing between polyp and nonpolyp regions. The results also indicated the importance of combining spatial and temporal features to further improve detection accuracy. Conclusions The developed software provided a means of detecting and quantifying polypoidal regions in ICGA images for the first time. Translational Relevance This preliminary study demonstrated a computer-aided diagnostic tool, which enables objective evaluation of PCV and its progression. Ophthalmologists can easily visualize the polypoidal regions and obtain quantitative information about polyps by using the proposed system. PMID:25806144

  10. Temporal patterns of diversity: Assessing the biotic and abiotic controls on ant assemblages

    USGS Publications Warehouse

    Dunn, R.R.; Parker, C.R.; Sanders, N.J.

    2007-01-01

    In this study, we use 12 months of data from 11 ant assemblages to test whether seasonal variation in ant diversity is governed by either the structuring influences of interspecific competition or environmental conditions. Because the importance of competition might vary along environmental gradients, we also test whether the signature of competition depends on elevation. We find little evidence that competition structures the seasonal patterns of activity in the ant assemblages considered, but find support for the effects of temperature on seasonal patterns of diversity, especially at low-elevation sites. Although, in general, both competition and the environment interact to structure ant assemblages, our results suggest that environmental conditions are the primary force structuring the seasonal activity of the ant assemblages studied here. ?? 2007 The Linnean Society of London.

  11. Discovering and Predicting Temporal Patterns of WiFi-interactive Social Populations

    E-print Network

    Li, Xiang; Vasilakos, Athanasios V

    2014-01-01

    Extensive efforts have been devoted to characterizing the rich connectivity patterns among the nodes (components) of such complex networks (systems), and in the course of development of research in this area, people have been prompted to address on a fundamental question: How does the fascinating yet complex topological features of a network affect or determine the collective behavior and performance of the networked system? While elegant attempts to address this core issue have been made, for example, from the viewpoints of synchronization, epidemics, evolutionary cooperation, and the control of complex networks, theoretically or empirically, this widely concerned key question still remains open in the newly emergent field of network science. Such fruitful advances also push the desire to understand (mobile) social networks and characterize human social populations with the interdependent collective dynamics as well as the behavioral patterns. Nowadays, a great deal of digital technologies are unobtrusively ...

  12. Temporal patterns in coral reef, seagrass and mangrove communities from Chengue bay CARICOMP site (Colombia): 1993-2008.

    PubMed

    Rodríguez-Ramírez, Alberto; Garzón-Ferreira, Jaime; Batista-Morales, Angélica; Gil, Diego L; Gómez-López, Diana Isabel; Gómez-Campo, Kelly; López-Londoño, Tomás; Navas-Camacho, Raúl; Reyes-Nivia, María Catalina; Vega-Sequeda, Johanna

    2010-10-01

    Few monitoring programs have simultaneously assessed the dynamics of linked marine ecosystems (coral reefs, seagrass beds and mangroves) to document their temporal and spatial variability. Based on CARICOMP protocol we evaluated permanent stations in coral reefs, seagrass beds and mangroves from 1993 to 2008 in Chengue Bay at the Tayrona Natural Park, Colombian Caribbean. Overall, the studied ecosystems showed a remarkable stability pattern over the monitoring period. While there were annual variations in coral reefs (coral cover) and mangroves (litterfall) caused by hurricane Lenny in 1999, particular trends in seagrass (leaf area index and leaf productivity) appear to reflect the natural variability in this ecosystem. We suggest that monitoring sites at the three marine ecosystems had in general a healthy development in the last 16 years. Our results are critical to locally improve the management strategies (Tayrona Natural Park) and to understand the long-term dynamics of closely associated marine ecosystems in the Caribbean. PMID:21299095

  13. A network that performs brute-force conversion of a temporal sequence to a spatial pattern: relevance to odor recognition.

    PubMed

    Sanders, Honi; Kolterman, Brian E; Shusterman, Roman; Rinberg, Dmitry; Koulakov, Alexei; Lisman, John

    2014-01-01

    A classic problem in neuroscience is how temporal sequences (TSs) can be recognized. This problem is exemplified in the olfactory system, where an odor is defined by the TS of olfactory bulb (OB) output that occurs during a sniff. This sequence is discrete because the output is subdivided by gamma frequency oscillations. Here we propose a new class of "brute-force" solutions to recognition of discrete sequences. We demonstrate a network architecture in which there are a small number of modules, each of which provides a persistent snapshot of what occurs in a different gamma cycle. The collection of these snapshots forms a spatial pattern (SP) that can be recognized by standard attractor-based network mechanisms. We will discuss the implications of this strategy for recognizing odor-specific sequences generated by the OB. PMID:25278870

  14. The Spatio-Temporal Distribution Patterns of Biting Midges of the Genus Culicoides in Salta Province, Argentina

    PubMed Central

    Aybar, Cecilia A. Veggiani; Juri, María J. Dantur; Santana, Mirta; de Grosso, Mercedes S. Lizarralde; Spinelli, Gustavo R.

    2012-01-01

    The goal of this survey was to analyze the spatio-temporal distribution patterns of Culicoides Latreille species (Diptera: Ceratopogonidae) and their relationship with environmental variables in Salta, northwestern Argentina. Culicoides were collected monthly from January 2003 through December 2005. The influence of the climatic variables on population abundance was analyzed with a multilevel Poisson regression. A total of 918 specimens belonging to five species were collected. The most abundant species was Culicoides paraensis Goeldi (65.5%), followed by Culicoides lahillei Iches (14.6%) and Culicoides debilipalpis Lutz (7.6%). The highest seasonal abundance for C. paraensis, C. debilipalpis and C. lahillei occurred during the spring and summer. A Poisson regression analysis showed that the mean maximum and minimum temperature and the mean maximum and minimum humidity were the variables with the greatest influence on the population abundance of Culicoides species. PMID:23461794

  15. Eolian sediment responses to late Quaternary climate changes: temporal and spatial patterns in the Sahara

    Microsoft Academic Search

    C. Sweezy

    2001-01-01

    This paper presents a compilation of eolian-based records of late Quaternary climate changes in the Sahara. Although the data are relatively sparse, when viewed as a whole, they reveal a general pattern of widespread eolian sediment mobilization prior to 11,000cal. years bp, eolian sediment stabilization from 11,000 to 5000cal. years bp, and a return to widespread eolian sediment mobilization after

  16. Timescales of Multineuronal Activity Patterns Reflect Temporal Structure of Visual Stimuli

    Microsoft Academic Search

    Ovidiu F. Jurjut; Danko Nikolic; Wolf Singer; Shan Yu; Martha N. Havenith; Raul C. Muresan; Olaf Sporns

    2011-01-01

    The investigation of distributed coding across multiple neurons in the cortex remains to this date a challenge. Our current understanding of collective encoding of information and the relevant timescales is still limited. Most results are restricted to disparate timescales, focused on either very fast, e.g., spike-synchrony, or slow timescales, e.g., firing rate. Here, we investigated systematically multineuronal activity patterns evolving

  17. Modeling self-organized spatio-temporal patterns of PIP3 and PTEN during spontaneous cell polarization

    NASA Astrophysics Data System (ADS)

    Knoch, Fabian; Tarantola, Marco; Bodenschatz, Eberhard; Rappel, Wouter-Jan

    2014-08-01

    During spontaneous cell polarization of Dictyostelium discoideum cells, phosphatidylinositol (3,4,5)-triphoshpate (PIP3) and PTEN (phosphatase tensin homolog) have been identified as key signaling molecules which govern the process of polarization in a self-organized manner. Recent experiments have quantified the spatio-temporal dynamics of these signaling components. Surprisingly, it was found that membrane-bound PTEN can be either in a high or low state, that PIP3 waves were initiated in areas lacking PTEN through an excitable mechanism, and that PIP3 was degraded even though the PTEN concentration remained low. Here we develop a reaction-diffusion model that aims to explain these experimental findings. Our model contains bistable dynamics for PTEN, excitable dynamics for PIP3, and postulates the existence of two species of PTEN with different dephosphorylation rates. We show that our model is able to produce results that are in good qualitative agreement with the experiments, suggesting that our reaction-diffusion model underlies the self-organized spatio-temporal patterns observed in experiments.

  18. SuperFly: a comparative database for quantified spatio-temporal gene expression patterns in early dipteran embryos

    PubMed Central

    Cicin-Sain, Damjan; Pulido, Antonio Hermoso; Crombach, Anton; Wotton, Karl R.; Jiménez-Guri, Eva; Taly, Jean-François; Roma, Guglielmo; Jaeger, Johannes

    2015-01-01

    We present SuperFly (http://superfly.crg.eu), a relational database for quantified spatio-temporal expression data of segmentation genes during early development in different species of dipteran insects (flies, midges and mosquitoes). SuperFly has a special focus on emerging non-drosophilid model systems. The database currently includes data of high spatio-temporal resolution for three species: the vinegar fly Drosophila melanogaster, the scuttle fly Megaselia abdita and the moth midge Clogmia albipunctata. At this point, SuperFly covers up to 9 genes and 16 time points per species, with a total of 1823 individual embryos. It provides an intuitive web interface, enabling the user to query and access original embryo images, quantified expression profiles, extracted positions of expression boundaries and integrated datasets, plus metadata and intermediate processing steps. SuperFly is a valuable new resource for the quantitative comparative study of gene expression patterns across dipteran species. Moreover, it provides an interesting test set for systems biologists interested in fitting mathematical gene network models to data. Both of these aspects are essential ingredients for progress toward a more quantitative and mechanistic understanding of developmental evolution. PMID:25404137

  19. Limnology in the Upper Paraná River floodplain: large-scale spatial and temporal patterns, and the influence of reservoirs.

    PubMed

    Roberto, M C; Santana, N N; Thomaz, S M

    2009-06-01

    Knowledge of abiotic limnological factors is important to monitor changes caused by humans, and to explain the structure and dynamics of populations and communities in a variety of inland water ecosystems. In this study, we used a long term data-set (eight years) collected in 10 habitats with different features (river channels, and connected and isolated lakes) to describe the spatial and temporal patterns of some of the principal limnological factors. In general, the degree of connectivity of the lakes, together with the rivers to which the lakes are connected, were important determinants of their limnological characteristics. These differences are expected, because rivers entering the floodplain come from different geological regions and are subject to different human impacts. At large spatial scales, these differences contribute to the increased habitat diversity of the floodplain and thus to its high biodiversity. With regard to temporal variation, Secchi-disk transparency increased, and total phosphorus decreased in the Paraná River main channel during the last 20 years. Although these changes are directly attributed to the several reservoir cascades located upstream, the closing of the Porto Primavera dam in 1998 enhanced this effect. The increase in water transparency explains biotic changes within the floodplain. The lower-phosphorus Paraná River water probably dilutes concentrations of this element in the floodplain waterbodies during major floods, with future consequences for their productivity. PMID:19738977

  20. Patterns in the Composition of Microbial Communities from a Subtropical River: Effects of Environmental, Spatial and Temporal Factors

    PubMed Central

    Liu, Lemian; Yang, Jun; Yu, Xiaoqing; Chen, Guangjie; Yu, Zheng

    2013-01-01

    Microbes are key components of aquatic ecosystems and play crucial roles in global biogeochemical cycles. However, the spatiotemporal dynamics of planktonic microbial community composition in riverine ecosystems are still poorly understood. In this study, we used denaturing gradient gel electrophoresis of PCR-amplified 16S and 18S rRNA gene fragments and multivariate statistical methods to explore the spatiotemporal patterns and driving factors of planktonic bacterial and microbial eukaryotic communities in the subtropical Jiulong River, southeast China. Both bacterial and microbial eukaryotic communities varied significantly in time and were spatially structured according to upper stream, middle-lower stream and estuary. Among all the environmental factors measured, water temperature, conductivity, PO4-P and TN/TP were best related to the spatiotemporal distribution of bacterial community, while water temperature, conductivity, NOx-N and transparency were closest related to the variation of eukaryotic community. Variation partitioning, based on partial RDA, revealed that environmental factors played the most important roles in structuring the microbial assemblages by explaining 11.3% of bacterial variation and 17.5% of eukaryotic variation. However, pure spatial factors (6.5% for bacteria and 9.6% for eukaryotes) and temporal factors (3.3% for bacteria and 5.5% for eukaryotes) also explained some variation in microbial distribution, thus inherent spatial and temporal variation of microbial assemblages should be considered when assessing the impact of environmental factors on microbial communities. PMID:24244735

  1. Spatial and Temporal Patterns of Deforestation in Rio Cajarí Extrative Reserve, Amapá, Brazil

    PubMed Central

    Funi, Claudia; Paese, Adriana

    2012-01-01

    The Rio Cajarí Extractive Reserve (RCER) is a sustainable use protected area located in Southern Amapá state, Brazil. This protected area is home to traditional agro-extractive families, but has been increasingly invaded by commercial agriculture producers. In this work, we test the hypothesis that the RCER implementation has distinctly affected spatial patterns of deforestation and rates of bare soil and secondary forest formation by the social groups occupying the protected area and its surrounding area. Detailed maps of vegetation cover and deforestation were elaborated, based on Landsat TM images from 1991, 1998, 2007 and 2008 and Linear Spectral Mixture Models. Based on an extensive fieldwork, patches were classified according to the agents causing deforestation and characterized with ten explanatory variables. A discriminant function analysis was used to identify homogeneous groups based on the data. Results show increased rates and distinct spatial patterns of deforestation by three groups: extractivists, non traditional commercial agriculture producers, and a less representative group constituted of miners, cattle and timber producers. In all analyzed dates, clearings by the extrativist community presented the highest total area and smaller average sizes and were located in close proximity to villages. Deforestation patches by the non-traditional group were exclusively associated with ombrophilous forests; these presented higher average sizes and proximity indexes, and showed increased aggregation and large cluster formation. No significant differences were observed in deforestation patterns by the three groups inside or outside the reserve. PMID:23284806

  2. Spatio-Temporal Patterns of Beaked Whale Echolocation Signals in the North Pacific

    PubMed Central

    Baumann-Pickering, Simone; Roch, Marie A.; Brownell Jr, Robert L.; Simonis, Anne E.; McDonald, Mark A.; Solsona-Berga, Alba; Oleson, Erin M.; Wiggins, Sean M.; Hildebrand, John A.

    2014-01-01

    At least ten species of beaked whales inhabit the North Pacific, but little is known about their abundance, ecology, and behavior, as they are elusive and difficult to distinguish visually at sea. Six of these species produce known species-specific frequency modulated (FM) echolocation pulses: Baird’s, Blainville’s, Cuvier’s, Deraniyagala’s, Longman’s, and Stejneger’s beaked whales. Additionally, one described FM pulse (BWC) from Cross Seamount, Hawai’i, and three unknown FM pulse types (BW40, BW43, BW70) have been identified from almost 11 cumulative years of autonomous recordings at 24 sites throughout the North Pacific. Most sites had a dominant FM pulse type with other types being either absent or limited. There was not a strong seasonal influence on the occurrence of these signals at any site, but longer time series may reveal smaller, consistent fluctuations. Only the species producing BWC signals, detected throughout the Pacific Islands region, consistently showed a diel cycle with nocturnal foraging. By comparing stranding and sighting information with acoustic findings, we hypothesize that BWC signals are produced by ginkgo-toothed beaked whales. BW43 signal encounters were restricted to Southern California and may be produced by Perrin’s beaked whale, known only from Californian waters. BW70 signals were detected in the southern Gulf of California, which is prime habitat for Pygmy beaked whales. Hubb’s beaked whale may have produced the BW40 signals encountered off central and southern California; however, these signals were also recorded off Pearl and Hermes Reef and Wake Atoll, which are well south of their known range. PMID:24465877

  3. Effect of Temporally Patterned TNF-? Delivery on In Vitro Osteogenic Differentiation of Mesenchymal Stem Cells Cultured on Biodegradable Polymer Scaffolds

    PubMed Central

    Mountziaris, Paschalia M.; Lehman, E. Dennis; Mountziaris, Ioannis; Sing, David C.; Kasper, F. Kurtis; Mikos, Antonios G.

    2013-01-01

    Recent insight into the critical role of pro-inflammatory cytokines, particularly tumor necrosis factor-? (TNF-?), in bone regeneration has heralded a new direction in the design of bone tissue engineering constructs. Previous studies have demonstrated that continuous delivery of 50 ng/ml TNF-? to mesenchymal stem cells (MSCs) cultured on three-dimensional (3D) biodegradable electrospun poly(?-caprolactone) (PCL) microfiber meshes stimulates mineralized matrix deposition, a marker of osteogenic differentiation. Since TNF-? exhibits a biphasic pattern of expression following bone fracture in vivo, the goal of this study was to investigate the effects of temporal patterns of TNF-? delivery on in vitro osteogenic differentiation of MSCs cultured on 3D electrospun PCL scaffolds. MSCs were cultured for 16 days and exposed to continuous, early, intermediate, or late TNF-? delivery. To further elucidate the effects of TNF-? on osteogenic differentiation, the study design included MSCs pre-cultured both in the presence and absence of the typically required osteogenic supplement dexamethasone. Mineralized matrix deposition was not observed in constructs with dexamethasone-naïve MSCs, suggesting that TNF-? is not sufficient to trigger in vitro osteogenic differentiation of MSCs. For MSCs precultured with dexamethasone, TNF-? suppressed ALP activity, an early marker of osteogenic differentiation, and stimulated mineralized matrix deposition, a late stage marker of MSC osteogenic differentiation. By elucidating the impact of temporal variations in TNF-? delivery on MSC osteogenic differentiation, our results offer insight into the regenerative mechanism of TNF-? and provide the necessary design parameters for a novel tissue engineering strategy that rationally controls TNF-? signaling to stimulate bone regeneration. PMID:23746285

  4. Daily Temporal Patterns of Heroin and Cocaine Use and Craving: Relationship with Business Hours Regardless of Actual Employment Status

    PubMed Central

    Phillips, Karran A.; Epstein, David H.; Preston, Kenzie L.

    2013-01-01

    Real-time monitoring of behavior using Ecological Momentary Assessment (EMA) has provided detailed data about daily temporal patterns of craving and use in cigarette smokers. We have collected similar data from a sample of cocaine and heroin users. Here we analyzed it in the context of its relationship with a societal construct of daily temporal organization: 9-to-5 business hours. In a 28-week prospective study, 112 methadone-maintained polydrug-abusing individuals initiated an electronic-diary entry and provided data each time they used cocaine, heroin, or both during weeks 4 to 28. EMA data were collected for 10,781 person-days and included: 663 cocaine-craving events, 710 cocaine-use events, 288 heroin-craving events, 66 heroin-use events, 630 craving-both-drugs events, and 282 use-of-both-drugs events. At baseline, 34% of the participants reported full-time employment in the preceding 3-year period. Most participants’ current employment status fluctuated throughout the study. In a generalized linear mixed model (SAS Proc Glimmix), cocaine use varied by time of day relative to business hours (p<0.0001) and there was a significant interaction between Day of the Week and Time Relative to Business Hours (p<0.002) regardless of current work status. Cocaine craving also varied by time of day relative to business hours (p<0.0001), however, there was no significant interaction between Day of the Week and Time Relative to Business Hours (p=.57). Heroin craving and use were mostly reported during business hours, but data were sparse. Cocaine craving is most frequent during business hours while cocaine use is more frequent after business hours. Cocaine use during business hours, but not craving, seems suppressed on most weekdays, but not weekends, suggesting that societal conventions reflected in business hours influence drug-use patterns even in individuals whose daily schedules are not necessarily dictated by employment during conventional business hours. PMID:23770647

  5. Microbial colonization induces dynamic temporal and spatial patterns of NF-?B activation in the zebrafish digestive tract

    PubMed Central

    Kanther, Michelle; Sun, Xiaolun; Mühlbauer, Marcus; Mackey, Lantz C.; Flynn, Edward J.; Bagnat, Michel; Jobin, Christian; Rawls, John F.

    2011-01-01

    Background & Aims The nuclear factor ?-light-chain enhancer of activated B cells (NF-?B) transcription factor pathway is activated in response to diverse microbial stimuli to regulate expression of genes involved in immune responses and tissue homeostasis. However, the temporal and spatial activation of NF-?B in response to microbial signals have not been determined in whole living organisms, and the molecular and cellular details of these responses are not well understood. We used in vivo imaging and molecular approaches to analyze NF-?B activation in response to the commensal microbiota in transparent gnotobiotic zebrafish. Methods We used DNA microarrays, in situ hybridization, and quantitative reverse transcription PCR analyses to study the effects of the commensal microbiota on gene expression in gnotobiotic zebrafish. Zebrafish PAC2 and ZFL cells were used to study the NF-?B signaling pathway in response to bacterial stimuli. We generated transgenic zebrafish that express enhanced green fluorescent protein under transcriptional control of NF-?B, and used them to study patterns of NF-?B activation during development and microbial colonization. Results Bacterial stimulation induced canonical activation of the NF-?B pathway in zebrafish cells. Colonization of germ-free transgenic zebrafish with a commensal microbiota activated NF-?B and led to up-regulation of its target genes in intestinal and extra-intestinal tissues of the digestive tract. Colonization with the bacterium Pseudomonas aeruginosa was sufficient to activate NF-?B, and this activation required a functional flagellar apparatus. Conclusions In zebrafish, transcriptional activity of NF-?B is spatially and temporally regulated by specific microbial factors. The observed patterns of NF-?B-dependent responses to microbial colonization indicate that cells in the gastrointestinal tract respond robustly to the microbial environment. PMID:21439961

  6. The response of streambed nitrogen cycling to spatial and temporal hyporheic vertical flux patterns and associated residence times

    NASA Astrophysics Data System (ADS)

    Briggs, M. A.; Lautz, L. K.; Hare, D. K.

    2011-12-01

    Small beaver dams enhance the development of patchy micro-environments along the stream corridor by trapping sediment and creating complex streambed morphologies. This generates intricate hyporheic flux patterns that govern the exchange of oxygen and redox sensitive solutes between the water column and the streambed, and exert control on the biogeochemical cycling of nitrogen. Specifically, flowpaths from the stream into the subsurface with low residence times create oxic conditions that favor nitrification, while flowpaths with longer residence times become anoxic and favor denitrification. To investigate these processes we collected vertical profiles of pore water upstream of two beaver dams in Wyoming, USA at nine locations with varied morphology. We sampled pore water to the 0.55 m depth every week for five weeks as stream discharge dropped by 45% and subsequently measured concentrations of dissolved oxygen and several redox sensitive solutes, including nitrate. Additionally, estimates of hyporheic flux along these nine vertical profiles through time were made using high-resolution heat data combined with 1-D heat transport modeling. The data show that areas of rapid, deep hyporheic flux at the glides immediately upstream of the dams were oxygen rich, and were generally sites of moderate net nitrification to at least the 0.35 m depth. These conditions were relatively steady over the study period. Hyporheic zones at sediment bars closest to the dams were hotspots of nitrate production to a depth of 0.35 m, with nitrate concentrations increasing by as much as 400% as vertical flux fell sharply and residence times increased over the study period. In contrast, shallow bars farther upstream from the dams showed increasing fluxes and decreased residence times, which caused a shift from net denitrification to net nitrification over the period at shallow depths. These results support previous work indicating threshold behavior of nitrogen cycling in response to flowpath residence time. Furthermore the threshold between oxic and anoxic conditions, and subsequently the zone of peak net nitrification, can be approached from either end of the redox spectrum simultaneously within the same system in response to complex temporal changes in vertical flux. Finally, pools were sites of weak hyporheic flux, overall anoxic conditions and net denitrification. These patterns offer more evidence of the complicated spatial and temporal patterns of nitrogen cycling in the hyporheic zone, but also show that flux patterns measured with 1-D heat transport models may be used to develop predictive relationships regarding streambed biogeochemical conditions and hot spots of nitrogen cycling.

  7. Three-dimensional hippocampal atrophy maps distinguish two common temporal lobe seizure–onset patterns

    PubMed Central

    Ogren, Jennifer A.; Bragin, Anatol; Wilson, Charles L.; Hoftman, Gil D.; Lin, Jack J.; Dutton, Rebecca A.; Fields, Tony A.; Toga, Arthur W.; Thompson, Paul M.; Engel, Jerome; Staba, Richard J.

    2009-01-01

    Summary Purpose Current evidence suggests that the mechanisms underlying depth electrode–recorded seizures beginning with hypersynchronous (HYP) onset patterns are functionally distinct from those giving rise to low-voltage fast (LVF) onset seizures. However, both groups have been associated with hippocampal atrophy (HA), indicating a need to clarify the anatomic correlates of each ictal onset type. We used three-dimensional (3D) hippocampal mapping to quantify HA and determine whether each onset group exhibited a unique distribution of atrophy consistent with the functional differences that distinguish the two onset morphologies. Methods Sixteen nonconsecutive patients with medically refractory epilepsy were assigned to HYP or LVF groups according to ictal onset patterns recorded with intracranial depth electrodes. Using preimplant magnetic resonance imaging (MRI), levels of volumetrically defined HA were determined by comparison with matched controls, and the distribution of local atrophy was mapped onto 3D hippocampal surface models. Results HYP and LVF groups exhibited significant and equivalent levels of HA ipsilateral to seizure onset. Patients with LVF onset seizures also showed significant contralateral volume reductions. On ipsilateral contour maps HYP patients exhibited an atrophy pattern consistent with classical hippocampal sclerosis (HS), whereas LVF atrophy was distributed more laterally and diffusely. Contralateral LVF maps also showed regions of subicular atrophy. Discussion The HS-like distribution of atrophy and the restriction of HA to the ipsilateral hippocampus in HYP patients are consistent with focal hippocampal onsets, and suggest a mechanism utilizing intrahippocampal circuitry. In contrast, the bilateral distribution of nonspecific atrophy in the LVF group may reflect mechanisms involving both hippocampal and extrahippocampal networks. PMID:19054395

  8. Multielemental analysis of tree rings: temporal accumulation patterns and relationships with air pollution

    SciTech Connect

    Baes, C.F. III; McLaughlin, S.B.

    1983-01-01

    Short-leaf pine (Pinus echinata) tree rings collected in East Tennessee showed steadily increasing concentrations of Al, Cd, Cu, Fe, Mn, Mo, Ti, and Zn over the past 20 to 25 years. In part, these increasing concentrations result from recent declines in tree growth rate, but when corrected for variations in growth rate, annual accumulations of many of these metals in xylem tissue has increased in recent years. The largest concentration increases with time were observed in rings from trees downwind of the 1200 MW(e) generating Kingston steam plant, which burns 4 x 10/sup 9/ kg coal per year. Trace metals concentrations in cambial tissues were found to be as high as ten times those in the most recently formed xylem, and concentrations of Al, Cd, Mn, and Zn are near levels that have been associated with toxic effects when found in above-ground tissues of herbaceous plants. In trees sampled in the Great Smoky Mountains National Park (GSMNP) there was a period of suppressed growth and increased iron concentration in rings formed between 1863 and 1912. During this time period 88 km upwind, smelting of iron and copper sulfide ores was occurring at the Copper Basin (Copperhill), near Ducktown, Tennessee. Associated with this smelting were large uncontrolled releases of SO/sub 2/ which killed all vegetation within 20 km of the Copper Basin. The patterns of growth suppression and iron accumulation observed in the GSMNP trees correspond remarkably well to the initiation of smelting operations in 1854, maximum uncontrolled SO/sub 2/ emissions in 1895, and the reduction in SO/sub 2/ emissions mandated by the US Supreme Court in 1908. This historical pattern and the widespread occurrence of similar patterns of growth suppression and increased iron concentrations in tree rings since the late 1950s provide strong inferential evidence of tree response to SO/sub 2/ deposition. 36 references, 3 figures, 1 table.

  9. Climatic and geographic temporal patterns of pain in the Multicenter Study of Hydroxyurea.

    PubMed

    Smith, Wally R; Bauserman, Robert L; Ballas, Samir K; McCarthy, William F; Steinberg, Martin H; Swerdlow, Paul S; Waclawiw, Myron A; Barton, Bruce A

    2009-11-01

    No multi-site comparisons have tested whether seasonally cold temperature or climate exacerbate pain intensity in sickle cell disease (SCD). We examined seasonal SCD pain intensity and frequency patterns and compared them with concurrent climate conditions (temperature and barometric pressure) and geography of patient residence in the Multicenter Study of Hydroxyurea (MSH). We conducted a time series analysis of the monthly average daily pain intensity (0-9 scale) and pain frequency of the 299 MSH patients from December 1991 to December 1994. We used both an unobserved component model (UCM) and a nonparametric local regression (LOESS) to probe for a cycle and/or trend associated with the time series. We also examined base mixed regression models of season, monthly average temperature and barometric pressure, and geographic region as stand-alone predictors of pain intensity and frequency. Expanded models included additional predictor variables. UCM and LOESS analyses showed a cyclic pattern of pain intensity and frequency with peaks in late Fall/early Winter and troughs in Spring. Base regression models showed colder seasons were significantly associated with greater pain intensity (p = .0035) but not frequency (p = .07); higher monthly temperatures were significantly associated with both lower pain intensity and pain frequency, but higher monthly barometric pressures were significantly associated with greater pain intensity and frequency (all p's < .0001); and northern sites had nonsignificantly higher pain intensity (p = .40) and frequency (p = .07) than southern sites. This pattern of results did not change in expanded models including other predictors. Our results suggest that seasonably colder temperatures exacerbate sickle cell-related pain, but low barometric pressure does not, and geographic region of residence is not significantly related to pain in this sample. PMID:19683393

  10. A typology of household-level adaptation to coastal flooding and its spatio-temporal patterns.

    PubMed

    Koerth, Jana; Vafeidis, Athanasios T; Carretero, Silvina; Sterr, Horst; Hinkel, Jochen

    2014-01-01

    The predicted sea-level rise and changes in storm surge regimes are expected to lead to an increasing risk of flooding in coastal regions. Accommodation can be an alternative to protection in many areas, with household-level adaptation potentially constituting an important element of such a strategy, as it can significantly reduce costs. To date, a systematic typology of household-level adaptation to coastal flooding does not exist. In order to bridge this gap, we conducted a series of quantitative surveys in different coastal areas in Denmark, Germany and Argentina. We applied a cluster analysis in order to categorise the adaptive behaviour of coastal households. Coastal households were found to cluster in four groups that we term: the comprehensives, the theoreticians, the minimalists and the structurals. With the exception of households focusing on the implementation of high-effort structural measures, our results show the affiliation to these groups to follow a specific temporal sequence. At the same time, large differences in category affiliation exist between the study areas. Risk communication tools can utilise our typology to selectively target specific types of households or to ensure that the information needs of all groups are addressed. PMID:25191638

  11. Temporal and spatial patterns of phytoplankton production in Tomales Bay, California, U.S.A.

    NASA Astrophysics Data System (ADS)

    Cole, Brian E.

    1989-01-01

    Primary productivity in the water column was measured 14 times between April 1985 and April 1986 at three sites in Tomales Bay, California, USA The conditions at these three stations encompassed the range of hydrographic conditions, phytoplankton biomass, phytoplankton community composition, and turbidity typical of this coastal embayment. Linear regression of the measured daily carbon uptake against the composite parameter BZpIo (where B is the average phytoplankton biomass in the photic zone; Zp is the photic depth; and Io is the daily surface insolation) indicates that 90% of the variability in primary productivity is explained by variations in phytoplankton biomass and light availability. The linear function derived using Tomales Bay data is essentially the same as that which explains more than 80% of the variation in productivity in four other estuarine systems. Using the linear function and measured values for B, Zp, and Io, the daily photic-zone productivity was estimated for 10 sites at monthly intervals over the annual period. The average daily photic-zone productivity for the 10 sites ranged from 0·2 to 2·2 g C m -2. The bay-wide average annual primary productivity in the water column was 400 g C m -2, with most of the uptake occuring in spring and early summer. Spatial and temporal variations in primary productivity were similar to variations in phytoplankton biomass. Productivity was highest in the seaward and central regions of the bay and lowest in the shallow landward region.

  12. Assessing the temporal stability of spatial patterns of soil apparent electrical conductivity using geophysical methods

    NASA Astrophysics Data System (ADS)

    De Caires, Sunshine A.; Wuddivira, Mark N.; Bekele, Isaac

    2014-10-01

    Cocoa remains in the same field for decades, resulting in plantations dominated with aging trees growing on variable and depleted soils. We determined the spatio-temporal variability of key soil properties in a (5.81 ha) field from the International Cocoa Genebank, Trinidad using geophysical methods. Multi-year (2008-2009) measurements of apparent electrical conductivity at 0-0.75 m (shallow) and 0.75-1.5 m (deep) were conducted. Apparent electrical conductivity at deep and shallow gave the strongest linear correlation with clay-silt content (R = 0.67 and R = 0.78, respectively) and soil solution electrical conductivity (R = 0.76 and R = 0.60, respectively). Spearman rank correlation coefficients ranged between 0.89-0.97 and 0.81- 0.95 for apparent electrical conductivity at deep and shallow, respectively, signifying a strong linear dependence between measurement days. Thus, in the humid tropics, cocoa fields with thick organic litter layer and relatively dense understory cover, experience minimal fluctuations in transient properties of soil water and temperature at the topsoil resulting in similarly stable apparent electrical conductivity at shallow and deep. Therefore, apparent electrical conductivity at shallow, which covers the depth where cocoa feeder roots concentrate, can be used as a fertility indicator and to develop soil zones for efficient application of inputs and management of cocoa fields.

  13. Spatial and temporal patterns of Australian dynamic topography from River Profile Modeling

    NASA Astrophysics Data System (ADS)

    Czarnota, K.; Roberts, G. G.; White, N. J.; Fishwick, S.

    2014-02-01

    Despite its importance, the temporal and spatial evolution of continental dynamic topography is poorly known. Australia's isolation from active plate boundaries and its rapid northward motion within a hot spot reference frame make it a useful place to investigate the interplay between mantle convection, topography, and drainage. Offshore, dynamic topography is relatively well constrained and can be accounted for by Australia's translation over the mantle's convective circulation. To build a database of onshore constraints, we have analyzed an inventory of longitudinal river profiles, which is sensitive to uplift rate history. Using independently constrained erosional parameters, we determine uplift rates by minimizing the misfit between observed and calculated river profiles. Resultant fits are excellent and calculated uplift histories match independent geologic constraints. We infer that western and central Australia underwent regional uplift during the last 50 Myr and that the Eastern Highlands have been uplifted in two stages. The first stage from 120 to 80 Ma, coincided with rifting along the eastern margin and its existence is supported by thermochronological measurements. A second stage occurred at 80-10 Ma, formed the Great Escarpment, and coincided with Cenozoic volcanism. The relationship between topography, gravity anomalies, and shear wave tomographic models suggest that regional elevation is supported by temperature anomalies within the lithosphere's thermal boundary layer. Morphology and stratigraphy of the Eastern Highlands imply that these anomalies have been coupled to the base of the plate during Australia's northward motion over the last 70 Myr.

  14. Water quality assessment and analysis of spatial patterns and temporal trends.

    PubMed

    Gazzaz, Nabeel M; Yusoff, Mohd Kamil; Juahir, Hafizan; Ramli, Mohammad Firuz; Aris, Ahmad Zaharin

    2013-08-01

    This study investigated relationships of a water quality index (WQI) with multiple water quality variables (WQVs), explored variability in water quality over time and space, and established linear and non-linear models predictive of WQI from raw WQVs. Data were processed using Spearman's rank correlation analysis, multiple linear regression, and artificial neural network modeling. Correlation analysis indicated that from a temporal perspective, the WQI, temperature, and zinc, arsenic, chemical oxygen demand, sodium, and dissolved oxygen concentrations increased, whereas turbidity and suspended solids, total solids, nitrate nitrogen (NO3-N), and biochemical oxygen demand concentrations decreased with year. From a spatial perspective, an increase with distance of the sampling station from the headwater was exhibited by 10 WQVs: magnesium, calcium, dissolved solids, electrical conductivity, temperature, NO3-N, arsenic, chloride, potassium, and sodium. At the same time, the WQI; Escherichia coli bacteria counts; and suspended solids, total solids, and dissolved oxygen concentrations decreased with distance from the headwater. Lastly, regression and artificial neural network models with high prediction powers (81.2% and 91.4%, respectively) were developed and are discussed. PMID:24003601

  15. Spatial and temporal patterns in mercury contamination in sediments of the Laurentian Great Lakes.

    PubMed

    Marvin, Chris; Painter, Scott; Rossmann, Ronald

    2004-07-01

    Data from recent sediment surveys have been collated and mapped in order to determine the spatial distribution of mercury in sediments across the entire Great Lakes basin. Information from historical surveys has also been collated in order to evaluate temporal trends. Lake Huron (2002) exhibited the lowest mercury concentrations (lakewide average concentration, 0.043 microg/g); Lakes Michigan (1994-1996) and Superior (2000) also exhibited relatively low levels (lakewide averages of 0.088 and 0.078 microg/g, respectively). The western basin of Lake Erie (1997-1998, 0.402 microg/g) and Lake Ontario (0.586 microg/g) exhibited the highest levels. Sources of mercury contamination in Lakes Erie and Ontario are primarily attributed to loadings from historical sources, including chlor-alkali production in the Detroit, St. Clair, and Niagara Rivers. The spatial distributions of mercury in sediments of Lakes Huron and Superior suggest that natural geochemical factors are an influence. Surficial sediment mercury contamination was found to have decreased markedly since the late 1960s and 1970s. Decreases in lakewide average sediment concentrations of mercury over this time period ranged from approximately 25% for Lake Ontario to 80% for Lake Huron. PMID:15220069

  16. Temporal and spatial patterns in recruitment of three penaeid prawns in Moreton Bay, Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Courtney, A. J.; Masel, J. M.; Die, D. J.

    1995-10-01

    The size at recruitment, temporal and spatial distribution, and abiotic factors influencing abundance of three commercially important species of penaeid prawns in the sublittoral trawl grounds of Moreton Bay (Queensland, Australia) were compared. Metapenaeus bennettae and Penaeus plebejus recruit to the trawl grounds at sizes which are relatively small (14-15 mm carapace length, CL) and below that at which prawns are selected for, and retained, in the fleet's cod-ends. In contrast, Penaeus esculentus recruit at the relatively large size of 27 mm CL from February to May, well above the size ranges selected for. Recruitment of M. bennettae extends over several months, September-October and February-March, and was thus likely to be bi-annual, while the recruitment period of P. plebejus was distinct, peaking in October-November each year. Size classes of M. bennettae were the most spatially stratified of the three species. Catch rates of recruits were negatively correlated with depth for all three species, and were also negatively correlated with salinity for M. bennettae.

  17. Temporal Patterns of Happiness and Information in a Global Social Network: Hedonometrics and Twitter

    PubMed Central

    Dodds, Peter Sheridan; Harris, Kameron Decker; Kloumann, Isabel M.; Bliss, Catherine A.; Danforth, Christopher M.

    2011-01-01

    Individual happiness is a fundamental societal metric. Normally measured through self-report, happiness has often been indirectly characterized and overshadowed by more readily quantifiable economic indicators such as gross domestic product. Here, we examine expressions made on the online, global microblog and social networking service Twitter, uncovering and explaining temporal variations in happiness and information levels over timescales ranging from hours to years. Our data set comprises over 46 billion words contained in nearly 4.6 billion expressions posted over a 33 month span by over 63 million unique users. In measuring happiness, we construct a tunable, real-time, remote-sensing, and non-invasive, text-based hedonometer. In building our metric, made available with this paper, we conducted a survey to obtain happiness evaluations of over 10,000 individual words, representing a tenfold size improvement over similar existing word sets. Rather than being ad hoc, our word list is chosen solely by frequency of usage, and we show how a highly robust and tunable metric can be constructed and defended. PMID:22163266

  18. Patterns of cyto-nuclear linkage disequilibrium in Silene latifolia: genomic heterogeneity and temporal stability

    PubMed Central

    Fields, P D; McCauley, D E; McAssey, E V; Taylor, D R

    2014-01-01

    Non-random association of alleles in the nucleus and cytoplasmic organelles, or cyto-nuclear linkage disequilibrium (LD), is both an important component of a number of evolutionary processes and a statistical indicator of others. The evolutionary significance of cyto-nuclear LD will depend on both its magnitude and how stable those associations are through time. Here, we use a longitudinal population genetic data set to explore the magnitude and temporal dynamics of cyto-nuclear disequilibria through time. We genotyped 135 and 170 individuals from 16 and 17 patches of the plant species Silene latifolia in Southwestern VA, sampled in 1993 and 2008, respectively. Individuals were genotyped at 14 highly polymorphic microsatellite markers and a single-nucleotide polymorphism (SNP) in the mitochondrial gene, atp1. Normalized LD (D?) between nuclear and cytoplasmic loci varied considerably depending on which nuclear locus was considered (ranging from 0.005–0.632). Four of the 14 cyto-nuclear associations showed a statistically significant shift over approximately seven generations. However, the overall magnitude of this disequilibrium was largely stable over time. The observed origin and stability of cyto-nuclear LD is most likely caused by the slow admixture between anciently diverged lineages within the species' newly invaded range, and the local spatial structure and metapopulation dynamics that are known to structure genetic variation in this system. PMID:24002238

  19. Patterns of cyto-nuclear linkage disequilibrium in Silene latifolia: genomic heterogeneity and temporal stability.

    PubMed

    Fields, P D; McCauley, D E; McAssey, E V; Taylor, D R

    2014-02-01

    Non-random association of alleles in the nucleus and cytoplasmic organelles, or cyto-nuclear linkage disequilibrium (LD), is both an important component of a number of evolutionary processes and a statistical indicator of others. The evolutionary significance of cyto-nuclear LD will depend on both its magnitude and how stable those associations are through time. Here, we use a longitudinal population genetic data set to explore the magnitude and temporal dynamics of cyto-nuclear disequilibria through time. We genotyped 135 and 170 individuals from 16 and 17 patches of the plant species Silene latifolia in Southwestern VA, sampled in 1993 and 2008, respectively. Individuals were genotyped at 14 highly polymorphic microsatellite markers and a single-nucleotide polymorphism (SNP) in the mitochondrial gene, atp1. Normalized LD (D') between nuclear and cytoplasmic loci varied considerably depending on which nuclear locus was considered (ranging from 0.005-0.632). Four of the 14 cyto-nuclear associations showed a statistically significant shift over approximately seven generations. However, the overall magnitude of this disequilibrium was largely stable over time. The observed origin and stability of cyto-nuclear LD is most likely caused by the slow admixture between anciently diverged lineages within the species' newly invaded range, and the local spatial structure and metapopulation dynamics that are known to structure genetic variation in this system. PMID:24002238

  20. Temporal and spatial patterns of phytoplankton production in Tomales Bay, California, U.S.A.

    USGS Publications Warehouse

    Cole, B.E.

    1989-01-01

    Primary productivity in the water column was measured 14 times between April 1985 and April 1986 at three sites in Tomales Bay, California, USA The conditions at these three stations encompassed the range of hydrographic conditions, phytoplankton biomass, phytoplankton community composition, and turbidity typical of this coastal embayment. Linear regression of the measured daily carbon uptake against the composite parameter B Zp Io (where B is the average phytoplankton biomass in the photic zone; Zp is the photic depth; and Io is the daily surface insolation) indicates that 90% of the variability in primary productivity is explained by variations in phytoplankton biomass and light availability. The linear function derived using Tomales Bay data is essentially the same as that which explains more than 80% of the variation in productivity in four other estuarine systems. Using the linear function and measured values for B, Zp, and Io, the daily photic-zone productivity was estimated for 10 sites at monthly intervals over the annual period. The average daily photic-zone productivity for the 10 sites ranged from 0??2 to 2??2 g C m-2. The bay-wide average annual primary productivity in the water column was 400 g C m-2, with most of the uptake occuring in spring and early summer. Spatial and temporal variations in primary productivity were similar to variations in phytoplankton biomass. Productivity was highest in the seaward and central regions of the bay and lowest in the shallow landward region. ?? 1989.

  1. Spatial and Temporal Patterns of Apparent Electrical Conductivity: DUALEM vs. Veris Sensors for Monitoring Soil Properties

    PubMed Central

    Serrano, João; Shahidian, Shakib; da Silva, José Marques

    2014-01-01

    The main objective of this study was to compare two apparent soil electrical conductivity (ECa) sensors (Veris 2000 XA and DUALEM 1S) for mapping variability of soil properties in a Mediterranean shallow soil. This study also aims at studying the effect of soil cover vegetation on the ECa measurement by the two types of sensors. The study was based on two surveys carried out under two very different situations: in February of 2012, with low soil moisture content (SMC) and with high and differentiated vegetation development (non grazed pasture), and in February of 2013, with high SMC and with short and relatively homogeneous vegetation development (grazed pasture). The greater temporal stability of Veris sensor, despite the wide variation in the SMC and vegetation ground cover indicates the suitability of using this sensor for monitoring soil properties in permanent pastures. The survey carried out with the DUALEM sensor in 2012 might have been affected by the presence of a 0.20 m vegetation layer at the soil surface, masking the soil properties. These differences should be considered in the selection of ECa sensing systems for a particular application. PMID:24915182

  2. Holographic interferometry applied to characterize the near-field acoustic displacement patterns and dynamics of operating sonar arrays

    NASA Astrophysics Data System (ADS)

    Fein, Howard

    1995-07-01

    The dynamic acoustic information processed by a sonar array is of critical importance to target discrimination and recognition. A visualization of the true near-field acoustic energy distribution of an active sonar array would be of great value to understanding and characterizing the effects of structural defects in the array and its interface to the water medium. Knowledge of the projected near-field acoustic energy would also enhance the analysis of returned sonar signals for homing and target recognition. Holographic interferometry has presented itself as a viable and useful method for the realization of this type of information.

  3. Spatio-temporal Patterns in Arcsecond-scale Flux Emergence Events

    NASA Astrophysics Data System (ADS)

    Lamb, Derek A.; DeForest, Craig

    2015-04-01

    Active regions’ pattern of magnetic flux emergence across latitude and time has been well described for nearly a century, and is generally understood in the context of the solar cycle. The pattern of emergence at smaller scales is thought to be basically random in space and time. Case studies of certain small-scale emergence events have suggested the possibility that some of these events are related to others in some way: the observations typically show simultaneous emergence events in close proximity to each other, and in some cases also with a similarity in the geometric orientation of the events. Whether these events are merely chance encounters, or signify a subsurface topological connection has not been addressed. Here we present SDO/HMI observations of some case studies of this clustered flux emergence, as well as a catalog of flux emergence events over a short time period, obtained through both manual and automated methods. Finally, we present a preliminary statistical analysis of the flux emergence events to determine whether these are simply an effect of an acute, imaginative human visual system or significantly unlikely to be chance encounters.

  4. Spatial and Temporal Fracture Pattern in Breast and Gynecologic Cancer Survivors

    PubMed Central

    Hui, Susanta K; Arentsen, Luke; Wilcox, Anjali; Shanley, Ryan; Yee, Douglas; Ghebre, Rahel

    2015-01-01

    Objective(s): To assess skeletal wide fracture location and time of fracture after cancer treatment Study Design: One hundred thirty-nine women diagnosed with breast or gynecologic cancer between 2003 and 2012 that subsequently had a radiologic diagnosis of fracture were identified retrospectively using electronic medical records. Results were compared with skeletal fracture pattern previously reported for a general population. Results: Skeletal fractures in cancer patients occur throughout the entire skeleton similar to general population. The most common sites were vertebrae (16%), feet and toes (15%), ribs (12%), hands and fingers (10%), and pelvis (8%). Fracture incidence was observed starting within the first year of survivorship, and continued to after five years. The median time from cancer diagnosis to fracture varied by age (p<0.01), from a high of 3.2 years for ages 50-59 to a low of 1.2 years for patients older than 70. Conclusion: The pattern of skeletal fracture is similar between cancer survivor and general population. Contrary to general assumption, survivors can experience skeletal fracture early after cancer treatment, especially at an older age. Thus, cancer survivorship care should include assessment of early time points with improved management of cancer treatment related bone injury. PMID:25553090

  5. Multivoxel patterns in face-sensitive temporal regions reveal an encoding schema based on detecting life in a face

    PubMed Central

    Looser, Christine E.; Guntupalli, Jyothi S.

    2013-01-01

    More than a decade of research has demonstrated that faces evoke prioritized processing in a ‘core face network’ of three brain regions. However, whether these regions prioritize the detection of global facial form (shared by humans and mannequins) or the detection of life in a face has remained unclear. Here, we dissociate form-based and animacy-based encoding of faces by using animate and inanimate faces with human form (humans, mannequins) and dog form (real dogs, toy dogs). We used multivariate pattern analysis of BOLD responses to uncover the representational similarity space for each area in the core face network. Here, we show that only responses in the inferior occipital gyrus are organized by global facial form alone (human vs dog) while animacy becomes an additional organizational priority in later face-processing regions: the lateral fusiform gyri (latFG) and right superior temporal sulcus. Additionally, patterns evoked by human faces were maximally distinct from all other face categories in the latFG and parts of the extended face perception system. These results suggest that once a face configuration is perceived, faces are further scrutinized for whether the face is alive and worthy of social cognitive resources. PMID:22798395

  6. Multispecies spawning sites for fishes on a low-latitude coral reef: spatial and temporal patterns.

    PubMed

    Claydon, J A B; McCormick, M I; Jones, G P

    2014-04-01

    Spawning sites used by one or more species were located by intensively searching nearshore coral reefs of Kimbe Bay (New Britain, Papua New Guinea). Once identified, the spawning sites were surveyed repeatedly within fixed 5?m radius circular areas, for ?>?2000 h of observations ranging from before dawn to after dusk spanning 190 days between July 2001 and May 2004. A total of 38 spawning sites were identified on the seven study reefs distributed at an average of one site every 60?m of reef edge. Pelagic spawning was observed in 41 fish species from six families. On three intensively studied reefs, all 17 spawning sites identified were used by at least three species, with a maximum of 30 different species observed spawning at a single site. Spawning was observed during every month of the study, on all days of the lunar month, at all states of the tide and at most hours of the day studied. Nevertheless, the majority of species were observed spawning on proportionately more days from December to April, on more days around the new moon and in association with higher tides. The strongest temporal association, however, was with species-specific diel spawning times spanning?

  7. Use of temporal patterns in vapor pressure deficit to explain spatial autocorrelation dynamics in tree transpiration.

    PubMed

    Adelman, Jonathan D; Ewers, Brent E; Mackay, D Scott

    2008-04-01

    To quantify the relationship between temporal and spatial variation in tree transpiration, we measured sap flow in 129 trees with constant-heat sap flow sensors in a subalpine forest in southern Wyoming, USA. The forest stand was located along a soil water gradient from a stream side to near the top of a ridge. The stand was dominated by Pinus contorta Dougl. ex Loud. with Picea engelmannii Parry ex Engelm and Abies lasiocarpa (Hook.) Nutt. present near the stream and scattered individuals of Populus tremuloides Michx. throughout the stand. We used a cyclic sampling design that maximized spatial information with a minimum number of samples for semivariogram analyses. All species exhibited previously established responses to environmental variables in which the dominant driver was a saturating response to vapor pressure deficit (D). This response to D is predictable from tree hydraulic theory in which stomatal conductance declines as D increases to prevent excessive cavitation. The degree to which stomatal conductance declines with D is dependent on both species and individual tree physiology and increases the variability in transpiration as D increases. We quantified this variability spatially by calculating the spatial autocorrelation within 0.2-kPa D bins. Across 11 bins of D, spatial autocorrelation in individual tree transpiration was inversely correlated to D and dropped from 45 to 20 m. Spatial autocorrelation was much less for transpiration per unit leaf area and not significant for transpiration per unit sapwood area suggesting that spatial autocorrelation within a particular D bin could be explained by tree size. Future research should focus on the mechanisms underlying tree size spatial variability, and the potentially broad applicability of the inverse relationship between D and spatial autocorrelation in tree transpiration. PMID:18244950

  8. Spatial and temporal patterns of air concentrations of mercury in Western North America 1998-present

    NASA Astrophysics Data System (ADS)

    Weiss-Penzias, P. S.; Eckley, C.; Parsons, M.; Gustin, M. S.; Jaffe, D. A.; Morris, K.; Obrist, D.; Mintz, R.; Steffen, A.; Cole, A. S.; Perry, K. D.; Rothenberg, S. E.; Gay, D.; Schmeltz, D.

    2013-12-01

    The Western North America Mercury Synthesis (WNAMS) is a collaborative effort to integrate information on mercury (Hg) emissions, transport and deposition, as well as methyl mercury (MeHg) production, bioaccumulation, and risk across the Western U.S., Canada, and Mexico. Air concentrations of Hg which include gaseous elemental (GEM), gaseous oxidized (GOM) and particulate (PBM) taken with the Tekran system since 1998, were evaluated with the goal of identifying spatial and temporal trends as well as information on sources, sinks, and processes. Twenty-eight sites spanning the region from the Yukon to Southern California and east to Utah have records of GEM, while GOM and PBM were measured at 13 and 10 sites respectively. The mean concentration of GEM across all sites was 1.55 ng m-3 and ranged between 1.22 and 2.55 ng m-3 at Whistler, British Columbia and Wells, Nevada, respectively. In general the sites in the desert areas of Nevada, Idaho and Utah had the highest GEM concentrations, probably due to local geogenic sources. Despite uncertainties associated with GOM and PBM measurements there were some observed trends. Mean GOM concentrations were generally correlated with site elevation, being highest at Great Basin National Park, Nevada (63 pg m-3, 2080 m asl) and lowest at Elkhorn Slough, California (< 1 pg m-3, 20 m asl). Diel variations of GEM were consistent with midday maxima morning minima at most sites except for the aforementioned desert areas which had nighttime maxima and afternoon minima. GOM displayed afternoon maxima at all sites except mountain/ridge-top sites which showed nighttime maxima. Out of six sites with > 5 years of GEM measurements, five sites displayed negative trends in annually averaged concentrations ranging from 0.02 to 0.05 ng m-3 y-1.

  9. Temporal metatranscriptomic patterning in phototrophic Chloroflexi inhabiting a microbial mat in a geothermal spring

    PubMed Central

    Klatt, Christian G; Liu, Zhenfeng; Ludwig, Marcus; Kühl, Michael; Jensen, Sheila I; Bryant, Donald A; Ward, David M

    2013-01-01

    Filamentous anoxygenic phototrophs (FAPs) are abundant members of microbial mat communities inhabiting neutral and alkaline geothermal springs. Natural populations of FAPs related to Chloroflexus spp. and Roseiflexus spp. have been well characterized in Mushroom Spring, where they occur with unicellular cyanobacteria related to Synechococcus spp. strains A and B?. Metatranscriptomic sequencing was applied to the microbial community to determine how FAPs regulate their gene expression in response to fluctuating environmental conditions and resource availability over a diel period. Transcripts for genes involved in the biosynthesis of bacteriochlorophylls (BChls) and photosynthetic reaction centers were much more abundant at night. Both Roseiflexus spp. and Chloroflexus spp. expressed key genes involved in the 3-hydroxypropionate (3-OHP) carbon dioxide fixation bi-cycle during the day, when these FAPs have been thought to perform primarily photoheterotrophic and/or aerobic chemoorganotrophic metabolism. The expression of genes for the synthesis and degradation of storage polymers, including glycogen, polyhydroxyalkanoates and wax esters, suggests that FAPs produce and utilize these compounds at different times during the diel cycle. We summarize these results in a proposed conceptual model for temporal changes in central carbon metabolism and energy production of FAPs living in a natural environment. The model proposes that, at night, Chloroflexus spp. and Roseiflexus spp. synthesize BChl, components of the photosynthetic apparatus, polyhydroxyalkanoates and wax esters in concert with fermentation of glycogen. It further proposes that, in daytime, polyhydroxyalkanoates and wax esters are degraded and used as carbon and electron reserves to support photomixotrophy via the 3-OHP bi-cycle. PMID:23575369

  10. Ozone in Rural Nevada: Investigating spatio-temporal patterns and source regions contributing to elevated concentrations

    NASA Astrophysics Data System (ADS)

    Fine, Rebekka

    In 1993, an ozone (O3) monitoring site was established at Great Basin National Park (GBNP), located in rural eastern Nevada. Analyses of data from this site indicate that compliance with a revised National Ambient Air Quality Standard (NAAQS) ?70 ppb will be challenging. With the exception of GBNP, ambient O3 monitoring has been limited to the areas in and around the 3 urban areas of Nevada. The objectives of the research presented here were to (1) characterize spatial and temporal trends in ambient O 3 across rural Nevada, and (2) identify source regions contributing to elevated O3 in rural Nevada. To pursue these objectives, a network of 13 monitoring sites was established throughout rural Nevada over a period ranging from July 2011 to June 2014. Data from 6 sites during the first 2 years of measurement indicate that maximum MDA8 O3 ranged from 68 to 80 ppb. Ambient O3 measured at GBNP was significantly higher than that measured at other rural Nevada sites. Back trajectory analyses, vertical profile measurements from aircrafts and sondes, statistical analyses, as well as results of regional and global models were employed to identify sources contributing to elevated O3. Our analyses indicate that regional and global sources contribute to O3 at surface sites throughout rural Nevada and that the high elevation and complex terrain make the State ideally situated to intercept air from the free troposphere and thus, pollution derived from complex sources included long-range transport, stratospheric intrusions, and regional emissions. Our data suggest that regional and global cooperation will be necessary to comply with a revised NAAQS in rural Nevada.

  11. Feed-forward synchronization: propagation of temporal patterns along the retinothalamocortical pathway.

    PubMed Central

    Neuenschwander, Sergio; Castelo-Branco, Miguel; Baron, Jerome; Singer, Wolf

    2002-01-01

    Visual responses in the cortex and lateral geniculate nucleus (LGN) are often associated with synchronous oscillatory patterning. In this short review, we examine the possible relationships between subcortical and cortical synchronization mechanisms. Our results obtained from simultaneous multi-unit recordings show strong synchronization of oscillatory responses between retina, LGN and cortex, indicating that cortical neurons can be synchronized by oscillatory activity relayed through the LGN. This feed-forward synchronization mechanism operating in the 60 to 120 Hz frequency range was observed mostly for static stimuli. In response to moving stimuli, by contrast, cortical synchronization was independent of oscillatory inputs from the LGN, with oscillation frequency in the range of 30 to 60 Hz. The functional implications of synchronization of activity from parallel channels are discussed, in particular its significance for signal transmission and cortical integration processes. PMID:12626020

  12. Arabidopsis Roots and Shoots Show Distinct Temporal Adaptation Patterns toward Nitrogen Starvation1[W

    PubMed Central

    Krapp, Anne; Berthomé, Richard; Orsel, Mathilde; Mercey-Boutet, Stéphanie; Yu, Agnes; Castaings, Loren; Elftieh, Samira; Major, Hilary; Renou, Jean-Pierre; Daniel-Vedele, Françoise

    2011-01-01

    Nitrogen (N) is an essential macronutrient for plants. N levels in soil vary widely, and plants have developed strategies to cope with N deficiency. However, the regulation of these adaptive responses and the coordinating signals that underlie them are still poorly understood. The aim of this study was to characterize N starvation in adult Arabidopsis (Arabidopsis thaliana) plants in a spatiotemporal manner by an integrative, multilevel global approach analyzing growth, metabolites, enzyme activities, and transcript levels. We determined that the remobilization of N and carbon compounds to the growing roots occurred long before the internal N stores became depleted. A global metabolite analysis by gas chromatography-mass spectrometry revealed organ-specific differences in the metabolic adaptation to complete N starvation, for example, for several tricarboxylic acid cycle intermediates, but also for carbohydrates, secondary products, and phosphate. The activities of central N metabolism enzymes and the capacity for nitrate uptake adapted to N starvation by favoring N remobilization and by increasing the high-affinity nitrate uptake capacity after long-term starvation. Changes in the transcriptome confirmed earlier studies and added a new dimension by revealing specific spatiotemporal patterns and several unknown N starvation-regulated genes, including new predicted small RNA genes. No global correlation between metabolites, enzyme activities, and transcripts was evident. However, this multilevel spatiotemporal global study revealed numerous new patterns of adaptation mechanisms to N starvation. In the context of a sustainable agriculture, this work will give new insight for the production of crops with increased N use efficiency. PMID:21900481

  13. Spatio-Temporal Brain Mapping of Spatial Attention Effects on Pattern-Reversal ERPs

    PubMed Central

    Di Russo, Francesco; Stella, Alessandra; Spitoni, Grazia; Strappini, Francesca; Sdoia, Stefano; Galati, Gaspare; Hillyard, Steven A.; Spinelli, Donatella; Pitzalis, Sabrina

    2011-01-01

    Recordings of event-related potentials (ERPs) were combined with structural and functional magnetic resonance imaging (fMRI) to investigate the timing and localization of stimulus selection processes during visual-spatial attention to pattern-reversing gratings. Pattern reversals were presented in random order to the left and right visual fields at a rapid rate while subjects attended to the reversals in one field at a time. On separate runs stimuli were presented in the upper and lower visual quadrants. The earliest ERP component (C1, peaking at around 80 ms), which inverted in polarity for upper versus lower field stimuli and was localized in or near visual area V1, was not modulated by attention. In the latency range 80-250 ms multiple components were elicited that were increased in amplitude by attention and were co-localized with fMRI activations in specific visual cortical areas. The principal anatomical sources of these attention-sensitive components were localized by fMRI-seeded dipole modeling as follows: P1 (ca. 100 ms--source in motion-sensitive area MT+), C2 (ca. 130 ms-- same source as C1), N1a (ca. 145 ms-- source in horizontal intraparietal sulcus), N1b (ca. 165 ms-- source in fusiform gyrus, area V4/V8), N1c (ca. 180 ms-- source in posterior intraparietal sulcus, area V3A), and P2 (ca. 220 ms-- multiple sources, including parieto-occipital sulcus, area V6). These results support the hypothesis that spatial attention acts to amplify both feed-forward and feedback signals in multiple visual areas of both the dorsal and ventral streams of processing. PMID:21500317

  14. Hyperbaric oxygenation alters temporal expression pattern of superoxide dismutase 2 after cortical stab injury in rats

    PubMed Central

    Parabucki, Ana B.; Boži?, Iva D.; Bjelobaba, Ivana M.; Lavrnja, Irena C.; Brki?, Predrag D.; Jovanovi?, Tomislav S.; Savi?, Danijela Z.; Stojiljkovi?, Mirjana B.; Pekovi?, Sanja M.

    2012-01-01

    Aim To evaluate the effect of hyperbaric oxygen therapy (HBOT) on superoxide dismutase 2 (SOD2) expression pattern after the cortical stab injury (CSI). Methods CSI was performed on 88 male Wistar rats, divided into control, sham, lesioned, and HBO groups. HBOT protocol was the following: pressure applied was 2.5 absolute atmospheres, for 60 minutes, once a day for consecutive 3 or 10 days.? The pattern of SOD2 expression and cellular localization was analyzed using real-time polymerase chain reaction, Western blot, and double-label fluorescence immunohistochemistry. Neurons undergoing degeneration were visualized with Fluoro-Jade®B. Results CSI induced significant transient increase in SOD2 protein levels at day 3 post injury, which was followed by a reduction toward control levels at post-injury day 10. At the same time points, mRNA levels for SOD2 in the injured cortex were down-regulated. Exposure to HBO for 3 days considerably down-regulated SOD2 protein levels in the injured cortex, while after 10 days of HBOT an up-regulation of SOD2 was observed. HBOT significantly increased mRNA levels for SOD2 at both time points compared to the corresponding L group, but they were still lower than in controls. Double immunofluorescence staining revealed that 3 days after CSI, up-regulation of SOD2 was mostly due to an increased expression in reactive astrocytes surrounding the lesion site. HBOT attenuated SOD2 expression both in neuronal and astroglial cells. Fluoro-Jade®B labeling showed that HBOT significantly decreased the number of degenerating neurons in the injured cortex. Conclusion HBOT alters SOD2 protein and mRNA levels after brain injury in a time-dependent manner. PMID:23275324

  15. Spatio-temporal patterns of radon along the western fault of the Dead Sea Transform, NW Dead Sea

    NASA Astrophysics Data System (ADS)

    Steinitz, Gideon; Piatibratova, Oksana

    2014-05-01

    An extensive and strong radon anomaly is developed along the western boundary fault of the Dead Sea Transform in the NW sector of the Dead Sea. The anomaly, extending 15-20 km north-south, is developed in the gravel to the east and adjacent to the exposed boundary fault. The highest radon values occur in proximity to the fault scarp composed of Mesozoic carbonates. Using gamma and alpha detectors radon (Rn-222) is measured in the gravel at several sites, at depths of 1.5 -3 meters, at a time resolution of <1 hour. Relative to the main tectonic element these sites are located at a) on-fault positions, in the range of 1-30 meters to the east of the fault scarp, and b) off-fault positions located 600 and 800 meters east of the fault. The large variability of radon encountered entails systematic spatial and temporal patterns. Prominent signals occur in the annual and daily periodicity bands, as well as non-periodic multi-day variations (2-20 days). A multi-year trend is indicated at one site. Modulations occur among the different signal types. The annual variation influences the multi-day and the daily signals, and the multi-day variation is modulating the daily signal. The overall variation patterns as well modulations between types of signals differ among sites. These are manifested primarily as dissimilar temporal variation patterns that occur at on-fault and off-fault sites. On-fault sites exhibit very prominent annual variations and relatively weak signals in the daily band. Off-fault sites exhibit mild to weak annual variation and relatively intense signals in the diurnal band. Within the diurnal periodicity band the relative amplitude of the S1 and S2 periodicities differs among the on- and off-fault sites. Decomposition of the signal types and inter-site comparison shows that: a) significantly different signal patterns occur perpendicular to the fault trace, at on- and off-fault positions which are several hundred meters apart; b) similar patterns, especially of the multi-day signals, are observed from sites 3 to15 km apart at on-fault positions. Bearing in mind that: a) semi-confined conditions exists at 2.5-3 meter depth; b) the uniformity of the host rock (gravel) at the sites; c) the uniformity of the local climatic conditions, and d) the similar emplacement of the sensors - it is concluded that: 1) the patterns and their modulations are similar to those encountered in experimental simulations using radon within confined volumes; 2) above surface atmospheric influences can be excluded as drivers of the signals; 3) a remote above surface influence probably drives the periodic components of nuclear radiation from radon in the annual and diurnal bands; 4) the latter signals as well as the multi-day signals are modified and inter-modulated by near field geological (static) and geophysical (dynamic) influences. So far the nature of these near field influences is unidentified. Still systematically different influences are operating at on-fault versus off-fault positions. If verified then a new aspect in geodynamic research is implied.

  16. Spatial and temporal patterns of neutral and adaptive genetic variation in the endangered African wild dog (Lycaon pictus).

    PubMed

    Marsden, Clare D; Woodroffe, Rosie; Mills, Michael G L; McNutt, J Weldon; Creel, Scott; Groom, Rosemary; Emmanuel, Masenga; Cleaveland, Sarah; Kat, Pieter; Rasmussen, Gregory S A; Ginsberg, Joshua; Lines, Robin; André, Jean-Marc; Begg, Colleen; Wayne, Robert K; Mable, Barbara K

    2012-03-01

    Deciphering patterns of genetic variation within a species is essential for understanding population structure, local adaptation and differences in diversity between populations. Whilst neutrally evolving genetic markers can be used to elucidate demographic processes and genetic structure, they are not subject to selection and therefore are not informative about patterns of adaptive variation. As such, assessments of pertinent adaptive loci, such as the immunity genes of the major histocompatibility complex (MHC), are increasingly being incorporated into genetic studies. In this study, we combined neutral (microsatellite, mtDNA) and adaptive (MHC class II DLA-DRB1 locus) markers to elucidate the factors influencing patterns of genetic variation in the African wild dog (Lycaon pictus); an endangered canid that has suffered extensive declines in distribution and abundance. Our genetic analyses found all extant wild dog populations to be relatively small (N(e) ?temporal structure of microsatellite diversity and MHC diversity were correlated and strongly influenced by demographic stability and population size, indicating the effects of genetic drift in these small populations. Despite this correlation, we detected signatures of selection at the MHC, implying that selection has not been completely overwhelmed by genetic drift. PMID:22320891

  17. Classifying acoustic signals into phoneme categories: average and dyslexic readers make use of complex dynamical patterns and multifractal scaling properties of the speech signal.

    PubMed

    Hasselman, Fred

    2015-01-01

    Several competing aetiologies of developmental dyslexia suggest that the problems with acquiring literacy skills are causally entailed by low-level auditory and/or speech perception processes. The purpose of this study is to evaluate the diverging claims about the specific deficient peceptual processes under conditions of strong inference. Theoretically relevant acoustic features were extracted from a set of artificial speech stimuli that lie on a /bAk/-/dAk/ continuum. The features were tested on their ability to enable a simple classifier (Quadratic Discriminant Analysis) to reproduce the observed classification performance of average and dyslexic readers in a speech perception experiment. The 'classical' features examined were based on component process accounts of developmental dyslexia such as the supposed deficit in Envelope Rise Time detection and the deficit in the detection of rapid changes in the distribution of energy in the frequency spectrum (formant transitions). Studies examining these temporal processing deficit hypotheses do not employ measures that quantify the temporal dynamics of stimuli. It is shown that measures based on quantification of the dynamics of complex, interaction-dominant systems (Recurrence Quantification Analysis and the multifractal spectrum) enable QDA to classify the stimuli almost identically as observed in dyslexic and average reading participants. It seems unlikely that participants used any of the features that are traditionally associated with accounts of (impaired) speech perception. The nature of the variables quantifying the temporal dynamics of the speech stimuli imply that the classification of speech stimuli cannot be regarded as a linear aggregate of component processes that each parse the acoustic signal independent of one another, as is assumed by the 'classical' aetiologies of developmental dyslexia. It is suggested that the results imply that the differences in speech perception performance between average and dyslexic readers represent a scaled continuum rather than being caused by a specific deficient component. PMID:25834769

  18. Classifying acoustic signals into phoneme categories: average and dyslexic readers make use of complex dynamical patterns and multifractal scaling properties of the speech signal

    PubMed Central

    2015-01-01

    Several competing aetiologies of developmental dyslexia suggest that the problems with acquiring literacy skills are causally entailed by low-level auditory and/or speech perception processes. The purpose of this study is to evaluate the diverging claims about the specific deficient peceptual processes under conditions of strong inference. Theoretically relevant acoustic features were extracted from a set of artificial speech stimuli that lie on a /bAk/-/dAk/ continuum. The features were tested on their ability to enable a simple classifier (Quadratic Discriminant Analysis) to reproduce the observed classification performance of average and dyslexic readers in a speech perception experiment. The ‘classical’ features examined were based on component process accounts of developmental dyslexia such as the supposed deficit in Envelope Rise Time detection and the deficit in the detection of rapid changes in the distribution of energy in the frequency spectrum (formant transitions). Studies examining these temporal processing deficit hypotheses do not employ measures that quantify the temporal dynamics of stimuli. It is shown that measures based on quantification of the dynamics of complex, interaction-dominant systems (Recurrence Quantification Analysis and the multifractal spectrum) enable QDA to classify the stimuli almost identically as observed in dyslexic and average reading participants. It seems unlikely that participants used any of the features that are traditionally associated with accounts of (impaired) speech perception. The nature of the variables quantifying the temporal dynamics of the speech stimuli imply that the classification of speech stimuli cannot be regarded as a linear aggregate of component processes that each parse the acoustic signal independent of one another, as is assumed by the ‘classical’ aetiologies of developmental dyslexia. It is suggested that the results imply that the differences in speech perception performance between average and dyslexic readers represent a scaled continuum rather than being caused by a specific deficient component.

  19. Climatic Redistribution of Canada's Water Resources (CROCWR): An analysis of spatial and temporal hydrological trends and patterns in western Canada

    NASA Astrophysics Data System (ADS)

    Bawden, A. J.; Burn, D. H.; Prowse, T. D.

    2012-12-01

    Climate variability and change can have profound impacts on the hydrologic regime of a watershed. These effects are likely to be especially severe in regions particularly sensitive to changes in climate, such as the Canadian north, or when there are other stresses on the hydrologic regime, such as may occur when there are large withdrawals from, or land-use changes within, a watershed. A recent report of the Intergovernmental Panel on Climate Change (IPCC) stressed that future climate is likely to accelerate the hydrologic cycle and hence may affect water security in certain locations. For some regions, this will mean enhanced access to water resources, but because the effects will not be spatially uniform, other regions will experience reduced access. Understanding these patterns is critical for water managers and government agencies in western Canada - an area of highly contrasting hydroclimatic regimes and overlapping water-use and jurisdictional borders - as adapting to climate change may require reconsideration of inter-regional transfers and revised allocation of water resources to competing industrial sectors, including agriculture, hydroelectric production, and oil and gas. This research involves the detection and examination of spatial and temporal streamflow trends in western Canadian rivers as a response to changing climatic factors, including temperature, precipitation, snowmelt, and the synoptic patterns controlling these drivers. The study area, known as the CROCWR region, extends from the Pacific coast of British Columbia as far east as the Saskatchewan-Manitoba border and from the Canada-United States international border through a large portion of the Northwest Territories. This analysis examines hydrologic trends in monthly and annual streamflow for a collection of 34 hydrometric gauging stations believed to adequately represent the overall effects of climate variability and change on flows in western Canada by means of the Mann-Kendall non-parametric trend test. Large-scale spatial patterns are determined through examination of trends and contrasts between upper and lower reaches of individual sub-basins, as well as via analysis of streamflow redistributions within the CROCWR region as an entirety (i.e. north, south, east and/or west-moving patterns). Results are used to predict future implications of hydroclimatic variability and change on western Canada's water resources and recommend measures to be taken by water managers in response to these changes. This research is part of a larger hydroclimatic study that includes an analysis of the climatic drivers contributing to shifting flow regimes in western Canada as well as a study of the controlling synoptic patterns and teleconnections associated with changes in these driving forces.

  20. Temporal patterns of methane emissions from wetland rice fields treated by different modes of N application

    SciTech Connect

    Wassmann, R. [International Rice Research Institute, Los Banos (Philippines)] [International Rice Research Institute, Los Banos (Philippines); [Fraunhofer Institute for Atmospheric Environmental Research, Garmisch-Partenkirchen (Germany); Neue, H.U.; Lantin, R.S.; Aduna, J.B.; Alberto, M.C.R.; Andales, M.J.; Tan, M.J. [International Rice Research Institute, Los Banos (Philippines)] [International Rice Research Institute, Los Banos (Philippines); Hoffmann, H.; Papen, H. [Fraunhofer Institute for Atmospheric Environmental Research, Garmisch-Partenkirchen (Germany)] [Fraunhofer Institute for Atmospheric Environmental Research, Garmisch-Partenkirchen (Germany); Gon, H.A.C. D. van der [Agricultural Univ., Wageningen (Netherlands)

    1994-08-20

    Methane emission rates from wetland rice fields were determined in Los Banos (Philipppines) using an automatic system that allows continuous measurements over time. Methane emission was monitored in an irrigated Aquandic Epiaqualf planted to rice cultivar IR72. Urea fertilizer was applied using four modes: (1) broadcast 10 days after transplanting, (2) broadcast at transplanting, (3) broadcast and incorporated at final harrowing, and (4) deep placement as sulfur-coated granules. The treatments were laid out in a randomized complete block design with four replicates. Measurements were done in the 1991 wet season, 1992 dry season (four treatments), and the 1992 wet season (only treatment 3). Methane emission rates from the experimental plots showed pronounced season and diel variations. The diel pattern of methane emission rates followed a consistent pattern, with highest rates observed in the early afternoon and lowest rates in the early morning. Methane emission rate was generally highest at the ripening stage. The average methane emission rate during the 1992 dry season (190 mg CH{sub 4} m{sup {minus}2} d{sup {minus}1}) exceeded the average flux rates of the 1992 wet season (79 mg CH{sub 4} m{sup {minus}2} d{sup {minus}1}) by a factor of 2.4. The total methane emitted from these flooded rice fields amounted to 19 g CH{sub 4} m{sup {minus}2} in the dry season with rice yields of 5.2-6.3 ha{sup {minus}1} and 7 g CH{sub 4} m{sup {minus}2} in the wet season with rice yields of 2.4-3.3 t ha{sup {minus}1} regardless of the mode of N application. Significant amounts corresponding to 20% of the methane released under waterlogged conditions were released when the soil was drained after harvest. Emission rates increased sharply when the floodwater receded and macropores started to drain. Emission of methane stopped only when the soil became fully aerated. 25 refs., 5 figs., 1 tab.

  1. Discrimination of calling song models by the cricket, Teleogryllus oceanicus: the influence of sound direction on neural encoding of the stimulus temporal pattern and on phonotactic behavior

    Microsoft Academic Search

    Gerald S. Pollack

    1986-01-01

    Recordings were made from an identified auditory neuron, the omega neuron, in the cricketTeleogryllus oceanicus. Models of the conspecific calling song and of the song of another species were presented either singly or simultaneously, and the degree to which the temporal pattern of the conspecific model was encoded in the neuron's spike train was determined. When a single stimulus was

  2. Temporal expression patterns of diapause-associated genes in flesh fly pupae from the onset of diapause through post-diapause quiescence

    Microsoft Academic Search

    S. A. L. Hayward; S. C. Pavlides; S. P. Tammariello; J. P. Rinehart; D. L. Denlinger

    2005-01-01

    Distinct differences in the temporal expression patterns of genes associated with pupal diapause were noted in the flesh fly, Sarcophaga crassipalpis. The first change observed was a decline in expression of the gene encoding heat shock protein 90 (hsp90) 2 days after pupariation (1 day before the pupa reaches the phanerocephalic stage characteristic of diapause). In contrast, hsp23 and hsp70

  3. Spatio-temporal patterns of the Norway spruce decline in the Beskid ?l?ski and ?ywiecki (Western Carpathians) in southern Poland

    Microsoft Academic Search

    W. Grodzki

    A dramatic forest decline due to the bark beetle outbreak, which occurs in the Norway spruce stands in the Western Beskidy (southern Poland) since 2003, was started after severe physiological drought during winter time. An analysis describing some spatio-temporal characteristics of this process, with special regard to the patterns of bark beetle occurrence related to root fungal diseases, is presented.

  4. Using soil seed banks to assess temporal patterns of genetic variation in invasive plant populations.

    PubMed

    Fennell, Mark; Gallagher, Tommy; Vintro, Luis Leon; Osborne, Bruce

    2014-05-01

    Most research on the genetics of invasive plant species has focused on analyzing spatial differences among existing populations. Using a long-established Gunnera tinctoria population from Ireland, we evaluated the potential of using plants derived from seeds associated with different soil layers to track genetic variation through time. This species and site were chosen because (1) G. tinctoria produces a large and persistent seed bank; (2) it has been present in this locality, Sraheens, for ?90 years; (3) the soil is largely undisturbed; and (4) the soil's age can be reliably determined radiometrically at different depths. Amplified fragment length polymorphic markers (AFLPs) were used to assess differences in the genetic structure of 75 individuals sampled from both the standing population and from four soil layers, which spanned 18 cm (estimated at ?90 years based on (210)Pb and (137)Cs dating). While there are difficulties in interpreting such data, including accounting for the effects of selection, seed loss, and seed migration, a clear pattern of lower total allele counts, percentage polymorphic loci, and genetic diversity was observed in deeper soils. The greatest percentage increase in the measured genetic variables occurred prior to the shift from the lag to the exponential range expansion phases and may be of adaptive significance. These findings highlight that seed banks in areas with long-established invasive populations can contain valuable genetic information relating to invasion processes and as such, should not be overlooked. PMID:24967082

  5. Temporal patterns of cortical proliferation of glial cell populations after traumatic brain injury in mice

    PubMed Central

    Susarla, Bala T.S.; Villapol, Sonia; Yi, Jae-Hyuk; Geller, Herbert M.; Symes, Aviva J.

    2014-01-01

    TBI (traumatic brain injury) triggers an inflammatory cascade, gliosis and cell proliferation following cell death in the pericontusional area and surrounding the site of injury. In order to better understand the proliferative response following CCI (controlled cortical impact) injury, we systematically analyzed the phenotype of dividing cells at several time points post-lesion. C57BL/6 mice were subjected to mild to moderate CCI over the left sensory motor cortex. At different time points following injury, mice were injected with BrdU (bromodeoxyuridine) four times at 3-h intervals and then killed. The greatest number of proliferating cells in the pericontusional region was detected at 3 dpi (days post-injury). At 1 dpi, NG2+ cells were the most proliferative population, and at 3 and 7 dpi the Iba-1+ microglial cells were proliferating more. A smaller, but significant number of GFAP+ (glial fibrillary acidic protein) astrocytes proliferated at all three time points. Interestingly, at 3 dpi we found a small number of proliferating neuroblasts [DCX+ (doublecortin)] in the injured cortex. To determine the cell fate of proliferative cells, mice were injected four times with BrdU at 3 dpi and killed at 28 dpi. Approximately 70% of proliferative cells observed at 28 dpi were GFAP+ astrocytes. In conclusion, our data suggest that the specific glial cell types respond differentially to injury, suggesting that each cell type responds to a specific pattern of growth factor stimulation at each time point after injury. PMID:24670035

  6. Using soil seed banks to assess temporal patterns of genetic variation in invasive plant populations

    PubMed Central

    Fennell, Mark; Gallagher, Tommy; Vintro, Luis Leon; Osborne, Bruce

    2014-01-01

    Most research on the genetics of invasive plant species has focused on analyzing spatial differences among existing populations. Using a long-established Gunnera tinctoria population from Ireland, we evaluated the potential of using plants derived from seeds associated with different soil layers to track genetic variation through time. This species and site were chosen because (1) G. tinctoria produces a large and persistent seed bank; (2) it has been present in this locality, Sraheens, for ?90 years; (3) the soil is largely undisturbed; and (4) the soil's age can be reliably determined radiometrically at different depths. Amplified fragment length polymorphic markers (AFLPs) were used to assess differences in the genetic structure of 75 individuals sampled from both the standing population and from four soil layers, which spanned 18 cm (estimated at ?90 years based on 210Pb and 137Cs dating). While there are difficulties in interpreting such data, including accounting for the effects of selection, seed loss, and seed migration, a clear pattern of lower total allele counts, percentage polymorphic loci, and genetic diversity was observed in deeper soils. The greatest percentage increase in the measured genetic variables occurred prior to the shift from the lag to the exponential range expansion phases and may be of adaptive significance. These findings highlight that seed banks in areas with long-established invasive populations can contain valuable genetic information relating to invasion processes and as such, should not be overlooked. PMID:24967082

  7. Eolian sediment responses to late Quaternary climate changes: Temporal and spatial patterns in the Sahara

    USGS Publications Warehouse

    Swezey, C.

    2001-01-01