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1

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

E-print Network

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

Bohn, Kirsten

2

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

PubMed Central

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

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

2008-01-01

3

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

PubMed Central

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

Hofmann, Hilmar; Peeters, Frank

2013-01-01

4

Temporal spike pattern learning  

NASA Astrophysics Data System (ADS)

Sensory systems pass information about an animal’s environment to higher nervous system units through sequences of action potentials. When these action potentials have essentially equivalent wave forms, all information is contained in the interspike intervals (ISIs) of the spike sequence. How do neural circuits recognize and read these ISI sequences? We address this issue of temporal sequence learning by a neuronal system utilizing spike timing dependent plasticity (STDP). We present a general architecture of neural circuitry that can perform the task of ISI recognition. The essential ingredients of this neural circuit, which we refer to as “interspike interval recognition unit” (IRU) are (i) a spike selection unit, the function of which is to selectively distribute input spikes to downstream IRU circuitry; (ii) a time-delay unit that can be tuned by STDP; and (iii) a detection unit, which is the output of the IRU and a spike from which indicates successful ISI recognition by the IRU. We present two distinct configurations for the time-delay circuit within the IRU using excitatory and inhibitory synapses, respectively, to produce a delayed output spike at time t0+?(R) in response to the input spike received at time t0 . R is the tunable parameter of the time-delay circuit that controls the timing of the delayed output spike. We discuss the forms of STDP rules for excitatory and inhibitory synapses, respectively, that allow for modulation of R for the IRU to perform its task of ISI recognition. We then present two specific implementations for the IRU circuitry, derived from the general architecture that can both learn the ISIs of a training sequence and then recognize the same ISI sequence when it is presented on subsequent occasions.

Talathi, Sachin S.; Abarbanel, Henry D. I.; Ditto, William L.

2008-09-01

5

A Temporal Semantics for Workflow Control Patterns  

Microsoft Academic Search

We use a temporal logic to generate a temporal account (characterization) of workflow control patterns. This characterization not only permits the integration of the control workflow patterns with formal validation tools, such as constraint satisfaction or theorem proving systems, but also provides means to formally identify occurrences of the patterns. This approach leads to the study of business process modeling

Denis Gagné; André Trudel

2008-01-01

6

Segregation of complex acoustic scenes based on temporal coherence  

PubMed Central

In contrast to the complex acoustic environments we encounter everyday, most studies of auditory segregation have used relatively simple signals. Here, we synthesized a new stimulus to examine the detection of coherent patterns (‘figures’) from overlapping ‘background’ signals. In a series of experiments, we demonstrate that human listeners are remarkably sensitive to the emergence of such figures and can tolerate a variety of spectral and temporal perturbations. This robust behavior is consistent with the existence of automatic auditory segregation mechanisms that are highly sensitive to correlations across frequency and time. The observed behavior cannot be explained purely on the basis of adaptation-based models used to explain the segregation of deterministic narrowband signals. We show that the present results are consistent with the predictions of a model of auditory perceptual organization based on temporal coherence. Our data thus support a role for temporal coherence as an organizational principle underlying auditory segregation. DOI: http://dx.doi.org/10.7554/eLife.00699.001 PMID:23898398

Teki, Sundeep; Chait, Maria; Kumar, Sukhbinder; Shamma, Shihab; Griffiths, Timothy D

2013-01-01

7

Temporal Coding of Concurrent Acoustic Signals in Auditory Midbrain  

Microsoft Academic Search

A fundamental problem faced by the auditory system of hu- mans and other vertebrates is the segregation of concurrent vocal signals. To discriminate between individual vocalizations, the auditory system must extract information about each signal from the single temporal waveform that results from the sum- mation of the simultaneous acoustic signals. Here, we present the first report of midbrain coding

Deana A. Bodnar; Andrew H. Bass

1997-01-01

8

MINING TEMPORAL SEQUENCES TO DISCOVER INTERESTING PATTERNS  

E-print Network

MINING TEMPORAL SEQUENCES TO DISCOVER INTERESTING PATTERNS Edwin O. Heierman, III, G. Michael, Texas 76019-0015 {heierman, youngbld, cook@cse.uta.edu ABSTRACT When mining temporal sequences sequences. In this paper, we present a novel data mining technique based on the Minimum Description Length

Cook, Diane J.

9

Significance of temporal and spectral acoustic cues for sexual recognition in Xenopus laevis  

PubMed Central

As in many anurans, males of the totally aquatic species, Xenopus laevis, advertise their sexual receptivity using vocalizations. Unusually for anurans, X. laevis females also advertise producing a fertility call that results in courtship duets between partners. Although all X. laevis calls consist of repetitive click trains, male and female calls exhibit sex-specific acoustic features that might convey sexual identity. We tested the significance of the carrier frequency and the temporal pattern of calls using underwater playback experiments in which modified calls were used to evoke vocal responses in males. Since males respond differently to male and female calls, the modification of a key component of sexual identity in calls should change the male's response. We found that a female-like slow call rhythm triggers more vocal activity than a male-like fast rhythm. A call containing both a female-like temporal pattern and a female-like carrier frequency elicits higher levels of courtship display than either feature alone. In contrast, a male-like temporal pattern is sufficient to trigger typical male–male encounter vocalizations regardless of spectral cues. Thus, our evidence supports a role for temporal acoustic cues in sexual identity recognition and for spectral acoustic cues in conveying female attractiveness in X. laevis. PMID:17476767

Vignal, Clementine; Kelley, Darcy

2006-01-01

10

Resurgence of Temporal Patterns of Responding  

ERIC Educational Resources Information Center

The resurgence of temporal patterns of key pecking by pigeons was investigated in two experiments. In Experiment 1, positively accelerated and linear patterns of responding were established on one key under a discrete-trial multiple fixed-interval variable-interval schedule. Subsequently, only responses on a second key produced reinforcers…

Cancado, Carlos R. X.; Lattal, Kennon A.

2011-01-01

11

Resurgence of Temporal Patterns of Responding  

PubMed Central

The resurgence of temporal patterns of key pecking by pigeons was investigated in two experiments. In Experiment 1, positively accelerated and linear patterns of responding were established on one key under a discrete-trial multiple fixed-interval variable-interval schedule. Subsequently, only responses on a second key produced reinforcers according to a variable-interval schedule. When reinforcement on the second key was discontinued, positively accelerated and linear response patterns resurged on the first key, in the presence of the stimuli previously correlated with the fixed- and variable-interval schedules, respectively. In Experiment 2, resurgence was assessed after temporal patterns were directly reinforced. Initially, responding was reinforced if it approximated an algorithm-defined temporal pattern during trials. Subsequently, reinforcement depended on pausing during trials and, when it was discontinued, resurgence of previously reinforced patterns occurred for each pigeon and for 2 of 3 pigeons during a replication. The results of both experiments demonstrate the resurgence of temporally organized responding and replicate and extend previous findings on resurgence of discrete responses and spatial response sequences. PMID:21547067

CanCado, Carlos R. X; Lattal, Kennon A

2011-01-01

12

Auditory Temporal Pattern Discrimination and Reading Ability  

ERIC Educational Resources Information Center

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…

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

2004-01-01

13

Temporal coherence of acoustic signals in a fluctuating ocean.  

PubMed

Temporal coherence of acoustic signals propagating in a fluctuating ocean is important for many practical applications and has been studied intensively experimentally. However, only a few theoretical formulations of temporal coherence exist. In the present paper, a three-dimensional (3D) modal theory of sound propagation in a fluctuating ocean is used to derive closed-form equations for the spatial-temporal coherence function of a broadband signal. The theory is applied to the analysis of the temporal coherence of a monochromatic signal propagating in an ocean perturbed by linear internal waves obeying the Garrett-Munk (G-M) spectral model. In particular, the temporal coherence function is calculated for propagation ranges up to 10(4) km and for five sound frequencies: 12, 25, 50, 75, and 100 Hz. Then, the dependence of the coherence time (i.e., the value of the time lag at which the temporal coherence decreases by a factor of e) on range and frequency is studied. The results obtained are compared with experimental data and predictions of the path-integral theory. PMID:21682384

Voronovich, Alexander G; Ostashev, Vladimir E; Colosi, John A

2011-06-01

14

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

E-print Network

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

Benoit-Bird, Kelly J.

15

The acoustic reflex and temporary threshold shift: temporal characteristics.  

PubMed

One ear of each of seven normal-hearing subjects was exposed to a continuous 1000-Hz tone at 110 dB SPL for three minutes. During exposure, a broad-band noise at 100 dB SPL was presented to the contralateral ear. The noise was either continuous or pulsed. Four pulsed conditions employed repetition periods of 360, 180, 90, or 9 msec with a 50% duty cycle. A control condition in which no noise was presented was also included. Temporary threshold shift was measured at selected postexposure times at the frequency one-half octave above the exposure frequency. TTS2 was greatest for the control condition and least for the 360- and 180-msec conditions. Results are discussed in relation to the dynamics of the acoustic reflex, particularly reflex relaxation, reflex adaptation, and reflex temporal summation. PMID:904317

Karlovich, R S; Osier, H A; Gutnick, H N; Ivey, R G; Wolf, K; Schwimmer, S; Strennen, M L; Gerber, J

1977-09-01

16

Dynamic membrane structure induces temporal pattern formation.  

PubMed

The understanding of temporal pattern formation in biological systems is essential for insights into regulatory processes of cells. Concerning this problem, the present work introduces a model to explain the attachment/detachment cycle of MARCKS and PKC at the cell membrane, which is crucial for signal transduction processes. Our model is novel with regard to its driving mechanism: Structural changes within the membrane fuel an activator-inhibitor based global density oscillation of membrane related proteins. Based on simulated results of our model, phase diagrams were generated to illustrate the interplay of MARCKS and PKC. They predict the oscillatory behavior in the form of the number of peaks, the periodic time, and the damping constant depending on the amounts of MARCKS and PKC, respectively. The investigation of the phase space also revealed an unexpected intermediate state prior to the oscillations for high amounts of MARCKS in the system. The validation of the obtained results was carried out by stability analysis, which also accounts for further enhanced understanding of the studied system. It was shown, that the occurrence of the oscillating behavior is independent of the diffusion and the consumption of the reactants. The diffusion terms in the used reaction-diffusion equations only act as modulating terms and are not required for the oscillation. The hypothesis of our work suggests a new mechanism of temporal pattern formation in biological systems. This mechanism includes a classical activator-inhibitor system, but is based on the modifications of the membrane structure, rather than a reaction-diffusion system. PMID:24866013

Lippoldt, J; Händel, C; Dietrich, U; Käs, J A

2014-10-01

17

A Temporal Pattern Search Algorithm for Personal History Event Visualization  

Microsoft Academic Search

We present Temporal Pattern Search (TPS), a novel algorithm for searching for temporal patterns of events in historical personal histories. The traditional method of searching for such patterns uses an automaton-based approach over a single array of events, sorted by time stamps. Instead, TPS operates on a set of arrays, where each array contains all events of the same type,

Taowei David Wang; Amol Deshpande; Ben Shneiderman

2012-01-01

18

Surface wave patterns on acoustically levitated viscous liquid alloys  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

19

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

PubMed

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

Comins, Jordan A; Gentner, Timothy Q

2014-09-01

20

Spatial and temporal variations in acoustic propagation characteristics at the New England shelfbreak front  

Microsoft Academic Search

The spatial and temporal variability of the acoustic field in the region of a strong coastal shelfbreak front are examined, using the high-resolution environmental data from the 1996-1997 New England shelfbreak PRIMER experiment to provide input to acoustic propagation models. Specifically, the \\

J. F. Lynch; A. E. Newhall; B. Sperry; G. Gawarkiewicz; A. Fredricks; P. Tyack; C. S. Chiu; P. Abbot

2003-01-01

21

TEMPORAL PATTERN DISCOVERY FOR ANOMALY DETECTION IN A SMART HOME  

E-print Network

TEMPORAL PATTERN DISCOVERY FOR ANOMALY DETECTION IN A SMART HOME Vikramaditya Jakkula , Diane J, cook}@eecs.wsu.edu Keywords: Knowledge discovery, smart homes, anomaly detection, temporal relations and relations on smart home datasets [10]. This paper describes a method of discovering temporal relations

Cook, Diane J.

22

Scaling properties in temporal patterns of schizophrenia  

NASA Astrophysics Data System (ADS)

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.

Dünki, R. M.; Ambühl, B.

1996-02-01

23

A Temporal Pattern Search Algorithm for Personal History Event Visualization  

E-print Network

1 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, it allows TPS to skip many unnecessary events in personal histories. We show that TPS's running time

Shneiderman, Ben

24

A Temporal Pattern Search Algorithm for Personal History Event Visualization  

E-print Network

1 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 to skip many unnecessary events in personal histories. We show that TPS's running time is bounded by O(m2

Golbeck, Jennifer

25

Coding of multisensory temporal patterns in human superior temporal sulcus  

PubMed Central

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

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

2012-01-01

26

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

E-print Network

To investigate the utility of Acoustic Doppler Current Profilers (ADCPs) for estimating the spatial and temporal variability of zooplankton stocks in the northeastern Gulf of Mexico, acoustic data from a moored array of ADCPs were used...

Scott, Rebecca Lee

2012-06-07

27

Tunable Nanowire Patterning Using Standing Surface Acoustic Waves  

PubMed Central

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

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

28

Discovering Phonetic Coherence in Acoustic Patterns*  

E-print Network

. children must learn not only to listen. but to speak.. In the speech Signal, they must discover infonnation 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

29

Unidirectional acoustic transmission based on source pattern reconstruction  

NASA Astrophysics Data System (ADS)

It is demonstrated both theoretically and experimentally that unidirectional acoustic transmission can be achieved through a simple structure consisting of only a uniform stiff plate and periodic rectangular gratings. Essentially distinct from the previous related works based on the utilizing of nonlinear effect or the partial band of the sonic crystal, it is attributed to one-side pattern reconstruction of acoustic plane waves induced by the periodic gratings, which can be physically modeled by forced vibration of the plate under periodic loads. The current structure takes the advantages of high transmission efficiency, small size, and broad bandwidth, which should open more possibilities for the miniaturization and integration of the one-way acoustic devices as well as further improvement of their performance.

Li, Y.; Tu, J.; Liang, B.; Guo, X. S.; Zhang, D.; Cheng, J. C.

2012-09-01

30

Spatial, Temporal and Spatio-Temporal Patterns of Maritime Piracy  

PubMed Central

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

Marchione, Elio

2013-01-01

31

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

PubMed Central

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

2014-01-01

32

Spatial and temporal patterns in conterminous United States streamflow characteristics  

NASA Astrophysics Data System (ADS)

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.

McCabe, Gregory J.; Wolock, David M.

2014-10-01

33

MINING PREDICTIVE PATTERNS AND EXTENSION TO MULTIVARIATE TEMPORAL DATA  

E-print Network

pattern mining to explore the search space. It applies a novel evaluation technique for extracting a smallMINING PREDICTIVE PATTERNS AND EXTENSION TO MULTIVARIATE TEMPORAL DATA by Iyad Batal BS, University Hauskrecht, PhD, Associate Professor, Computer Science ii #12;Copyright © by Iyad Batal 2012 iii #12;MINING

Hauskrecht, Milos

34

Geospatial and Temporal Patterns of Preparatory Conduct among American Terrorists  

Microsoft Academic Search

Although terrorism research has made significant strides during the past five years, even the most rudimentary patterns of terrorists’ behaviors remain unknown to scholars and analysts. In the current study, we analyze spatial and temporal patterns of criminal acts related to a variety of American terrorism cases and attempt to provide insight into these questions: 1) where do terrorists live

Jackson Cothren; Brent L. Smith; Paxton Roberts; Kelly R. Damphousse

2008-01-01

35

A New Temporal Pattern Identification Method for Characterization and Prediction  

E-print Network

and the C4.5 decision tree algorithm. Index Terms--Temporal pattern identification, time series analysis, data mining, time delay embedding, optimization clustering, and genetic algorithms. æ 1 INTRODUCTION 1 patterns in big data that can generalize to accurate future decisions [2]." Similarly, Cabena et al

Povinelli, Richard J.

36

Complex temporal and spatial patterns in nonequilibrium systems  

SciTech Connect

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.

Swinney, H.L.

1991-09-01

37

Spatial-temporal coherence of acoustic signals propagating in a refractive, turbulent atmosphere.  

PubMed

Propagation of acoustic signals above an impedance ground in a refractive, turbulent atmosphere with spatial-temporal fluctuations in temperature and wind velocity is considered. Starting from a parabolic equation, and using the Markov approximation and a locally frozen turbulence hypothesis, closed-form equations for the spatial-temporal statistical moments of arbitrary order of the sound-pressure field are derived. The general theory provides a basis for analysis of many statistical characteristics of broadband and narrowband acoustic signals for different geometries of propagation: line-of-sight propagation, multipath propagation in a refractive atmosphere above an impedance ground, and sound scattering into a refractive shadow zone. As an example of application of this theory, the spatial-temporal coherence of narrowband acoustic signals for line-of-sight propagation is calculated and analyzed. The coherence time of acoustic signals is studied numerically for meteorological conditions ranging from cloudy to sunny conditions, and with light, moderate, and strong wind. The results obtained are compared with available experimental data. PMID:25373944

Ostashev, Vladimir E; Keith Wilson, D; Vecherin, Sergey N; Collier, Sandra L

2014-11-01

38

1988 Wet deposition temporal and spatial patterns in North America  

SciTech Connect

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.

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

1992-03-01

39

1988 Wet deposition temporal and spatial patterns in North America  

SciTech Connect

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.

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

1992-03-01

40

Spatial and Temporal Patterns of Soil Frost in the  

E-print Network

1 Spatial and Temporal Patterns of Soil Frost in the Northern Midwest United States Tushar Sinha · Why is soil frost important ? · Objectives · Study area · Methodology · Results · Conclusions #12;3 Why is soil frost important ? · Soil ice reduces infiltration, cohesion and soil strength · Increases

Cherkauer, Keith

41

Light distribution in mesic grasslands: Spatial patterns and temporal dynamics  

Microsoft Academic Search

Spatial patterns and temporal dynamics of light distribution were investigated using lacunarity analysis, a multi-scale measure of spatial heterogeneity, in three mesic grasslands with different disturbance regimes. Frequency dis- tributions of relative light intensity (RLI) were similar for the two non-disturbed grasslands, despite different composition (forbs vs. caespitose grass) resulting from different historical disturbance regimes prior to 1985, and different

Justin D. Derner; X. Ben Wu

2001-01-01

42

Spatial, temporal and muscle action patterns of Tai Chi gait  

Microsoft Academic Search

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

Ge Wu; Wei Liu; Juvena Hitt; Debra Millon

2004-01-01

43

Intimate femicide in Israel; temporal, social, and motivational patterns  

Microsoft Academic Search

This study investigated all (76) cases of intimate femicide (the killing of women by their intimate male partners) in Israel during the years 1990–1995. The analysis focused on temporal patterns, the representation of various population groups, and given motives. The findings show a relationship between the incidence of intimate femicide and a number of major events\\/processes experienced by Israeli society

Simha F. Landau; Susan Hattis Rolef

1998-01-01

44

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

45

Stereotyped temporal patterns in electrical communication BRUCE A. CARLSON & CARL D. HOPKINS  

E-print Network

Stereotyped temporal patterns in electrical communication BRUCE A. CARLSON & CARL D. HOPKINS patterning and can therefore be appropriately termed displays. `Scallops' are stereotyped, transient bursts the evolution, function and mechanisms of stereotyped temporal pattern generation. Ã? 2004 The Association

46

Speaker recognition with temporal cues in acoustic and electric hearing  

NASA Astrophysics Data System (ADS)

Natural spoken language processing includes not only speech recognition but also identification of the speaker's gender, age, emotional, and social status. Our purpose in this study is to evaluate whether temporal cues are sufficient to support both speech and speaker recognition. Ten cochlear-implant and six normal-hearing subjects were presented with vowel tokens spoken by three men, three women, two boys, and two girls. In one condition, the subject was asked to recognize the vowel. In the other condition, the subject was asked to identify the speaker. Extensive training was provided for the speaker recognition task. Normal-hearing subjects achieved nearly perfect performance in both tasks. Cochlear-implant subjects achieved good performance in vowel recognition but poor performance in speaker recognition. The level of the cochlear implant performance was functionally equivalent to normal performance with eight spectral bands for vowel recognition but only to one band for speaker recognition. These results show a disassociation between speech and speaker recognition with primarily temporal cues, highlighting the limitation of current speech processing strategies in cochlear implants. Several methods, including explicit encoding of fundamental frequency and frequency modulation, are proposed to improve speaker recognition for current cochlear implant users.

Vongphoe, Michael; Zeng, Fan-Gang

2005-08-01

47

Are temporal features crucial acoustic cues in dog vocal recognition?  

PubMed

To investigate the perceptual mechanisms underlying conspecific vocal recognition in canine species, eighteen dogs were presented with playbacks of normal and reversed versions of typical dog vocalizations. Auditory perception was analysed using the head-turn paradigm, a non-invasive technique extensively employed to study hemispheric specializations for processing conspecific vocalizations in primates. The results revealed that dogs usually turn their heads with the right ear leading (left hemisphere activation) in response to the forward version of their typical calls, and with either no bias and the left ear leading (right hemisphere activation) in response to the reversed call versions. Overall, our findings suggest that temporal features are determinant auditory cues for call sound recognition in dogs, and support earlier findings of the role of the left hemisphere in the analyses of intraspecific communication. PMID:22544303

Siniscalchi, Marcello; Lusito, Rita; Sasso, Raffaella; Quaranta, Angelo

2012-09-01

48

Temporal integration of acoustic and cutaneous stimuli shown in the blink reflex  

Microsoft Academic Search

Temporal integration of pairs of brief blink-eliciting acoustic and cutaneous stimuli was investigated to determine if there\\u000a was integration of stimuli from different modalities. Reflexes elicited by a tone burst or by a brief electrical shock to\\u000a the supraorbital nerve followed by a second tone burst or shock at short stimulus onset asynchronies (SOAs) were larger and\\u000a faster than control

Yvonne Plant; Geoffrey R. Hammond

1989-01-01

49

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

50

Temporal coherence of the acoustic field forward propagated through a continental shelf with random internal waves.  

PubMed

An analytical model derived from normal mode theory for the accumulated effects of range-dependent multiple forward scattering is applied to estimate the temporal coherence of the acoustic field forward propagated through a continental-shelf waveguide containing random three-dimensional internal waves. The modeled coherence time scale of narrow band low-frequency acoustic field fluctuations after propagating through a continental-shelf waveguide is shown to decay with a power-law of range to the -1/2 beyond roughly 1?km, decrease with increasing internal wave energy, to be consistent with measured acoustic coherence time scales. The model should provide a useful prediction of the acoustic coherence time scale as a function of internal wave energy in continental-shelf environments. The acoustic coherence time scale is an important parameter in remote sensing applications because it determines (i) the time window within which standard coherent processing such as matched filtering may be conducted, and (ii) the number of statistically independent fluctuations in a given measurement period that determines the variance reduction possible by stationary averaging. PMID:24180758

Gong, Zheng; Chen, Tianrun; Ratilal, Purnima; Makris, Nicholas C

2013-11-01

51

Acoustically induced strong interaction between two periodically patterned elastic plates  

NASA Astrophysics Data System (ADS)

We study the acoustic-induced interactions between a pair of identical elastic plates patterned with periodical structures. Remarkable mutual forces, both repulsions and attractions, have been observed in the subwavelength regime. The dramatic effect stems from the resonant enhancement of the local field sandwiched between the double plates. The parameter sensitivity of the magnitude and the sign of the interaction (i.e., repulsion or attraction) depend directly on the vibration morphology of the resonant mode. In practical applications, the sign of the interaction can be switched by controlling the external frequency. Both the adjustable magnitude and the switchable sign of the contactless interaction endow this simple and compact double-plate structure with great potential in ultrasonic applications.

Qiu, Chunyin; Xu, Shengjun; Ke, Manzhu; Liu, Zhengyou

2014-09-01

52

Acoustic droplet-hydrogel composites for spatial and temporal control of growth factor delivery and scaffold stiffness  

PubMed Central

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

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

2013-01-01

53

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

PubMed

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

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

2013-07-01

54

Atherosclerotic plaque characterization by spatial and temporal speckle pattern analysis  

NASA Astrophysics Data System (ADS)

Improved methods are needed to identify the vulnerable coronary plaques responsible for acute myocardial infraction or sudden cardiac death. We describe a method for characterizing the structure and biomechanical properties of atherosclerotic plaques based on speckle pattern fluctuations. Near-field speckle images were acquired from five human aortic specimens ex vivo. The speckle decorrelation time constant varied significantly for vulnerable aortic plaques (? = 40 ms) versus stable plaques (? = 400 ms) and normal aorta (? = 500 ms). These initial results indicate that different atherosclerotic plaque types may be distinguished by analysis of temporal and spatial speckle pattern fluctuations.

Tearney, Guillermo J.; Bouma, Brett E.

2002-04-01

55

1987 wet deposition temporal and spatial patterns in North America  

SciTech Connect

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.

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

1990-03-01

56

International Symposium on Pattern Recognition and Acoustical Imaging, Newport Beach, CA, Feb. 4-6, 1987, Proceedings  

SciTech Connect

Various papers on pattern recognition and acoustical imaging are presented. The general subjects considered include imaging, texture and speckle analysis in medical ultrasound, parameter estimation, material characterization and NDE, and pattern recognition. Individual topics discussed include: inverse scattering theory foundations of tomography with diffracting wavefields, acoustical image reconstruction algorithms, three-dimensional motion parameter estimation by holographic acoustical systems, pattern recognition in acoustic emission experiments, image reconstruction of flaws using ramp response signatures, and pattern recognition approach to nondestructive evaluation of materials.

Ferrari, L.A.

1987-01-01

57

Recurrent coupling improves discrimination of temporal spike patterns.  

PubMed

Despite the ubiquitous presence of recurrent synaptic connections in sensory neuronal systems, their general functional purpose is not well understood. A recent conceptual advance has been achieved by theories of reservoir computing in which recurrent networks have been proposed to generate short-term memory as well as to improve neuronal representation of the sensory input for subsequent computations. Here, we present a numerical study on the distinct effects of inhibitory and excitatory recurrence in a canonical linear classification task. It is found that both types of coupling improve the ability to discriminate temporal spike patterns as compared to a purely feed-forward system, although in different ways. For a large class of inhibitory networks, the network's performance is optimal as long as a fraction of roughly 50% of neurons per stimulus is active in the resulting population code. Thereby the contribution of inactive neurons to the neural code is found to be even more informative than that of the active neurons, generating an inherent robustness of classification performance against temporal jitter of the input spikes. Excitatory couplings are found to not only produce a short-term memory buffer but also to improve linear separability of the population patterns by evoking more irregular firing as compared to the purely inhibitory case. As the excitatory connectivity becomes more sparse, firing becomes more variable, and pattern separability improves. We argue that the proposed paradigm is particularly well-suited as a conceptual framework for processing of sensory information in the auditory pathway. PMID:22586392

Yuan, Chun-Wei; Leibold, Christian

2012-01-01

58

Measurement resolution of noise directivity patterns from acoustic flight tests  

NASA Technical Reports Server (NTRS)

The measurement resolution of noise directivity patterns from acoustic flight tests was investigated. Directivity angle resolution is affected by the data reduction parameters, the aircraft velocity and flyover altitude, and by deviations of the aircraft from the desired flight path. Equations are developed which determine bounds for the lateral and longitudinal directivity angle resolution as a function of the nominal directivity angle. The equations are applied to a flight test data base and the effects of several flight conditions and data reduction parameters on the directivity angle resolution are presented. The maximum directivity angle resolution typically occurs when the aircraft is at or near the overhead position. In general, directivity angle resolution improves with decreasing velocity, increasing altitude, increasing sampling rate, decreasing block size, and decreasing block averages. Deviations from the desired ideal flight path will increase the resolution. For the flight experiment considered in this study, an average of two flyovers were required at each test condition to obtain an acceptable flight path. The ability of the pilot to maintain the flight track improved with decreasing altitude, decreasing velocity, and practice. Due to the prevailing wind conditions, yaw angles of as much as 20 deg were required to maintain the desired flight path.

Conner, David A.

1989-01-01

59

Reconstructing spatial and temporal patterns of paleoglaciation across Central Asia  

NASA Astrophysics Data System (ADS)

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.

Stroeven, Arjen P.

2014-05-01

60

Bacterial colonization of Hydra hatchlings follows a robust temporal pattern.  

PubMed

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

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

2013-04-01

61

Temporal patterns in severe hemoptysis requiring bronchial artery embolization  

PubMed Central

Background Although some authors have suggested that there is some seasonal periodicity in hemoptysis, temporal patterns of hemoptysis have been poorly investigated. The aim of this study is to describe the temporal pattern of severe hemoptysis which required bronchial artery embolization (BAE). Methods All consecutive patients with at least one episode of hemoptysis which required BAE during a 13-year period were included. Recurring hemoptysis requiring BAE in a patient with previous embolization was included as a new hemoptysis event, unless it occurred within one month from the prior event. Lineal regression was applied to compute the tendency of occurrence of cases along 13 years of record data. The daily and monthly distributions of embolizations were used to study the weekly and monthly seasonal indexes. Results Hemoptysis requiring BAE occurred with some monthly variation demonstrated with two monthly peaks, with the first one occurring during April and the second one during November. Conclusion Hemoptysis occurred with two monthly peaks. This seasonal trend might be due to different prevalence of respiratory tract infections or to some weather variables. Identification of significant environmental factors could be useful to improve preventive measures. PMID:23217035

2012-01-01

62

Bacterial colonization of Hydra hatchlings follows a robust temporal pattern  

PubMed Central

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

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

2013-01-01

63

The incidence and temporal patterning of insomnia: a second study.  

PubMed

Whether subjects with insomnia exhibit good sleep on some interval basis is unclear. Prior research suggests that patients with insomnia are highly variable with respect to night-to-night sleep continuity, that more than 40% of patients exhibit temporal patterning of good sleep, and that nearly 90% of patients exhibit better than average sleep following 1 to 3 nights of relatively poor sleep. The aim of the present study was to replicate and extend the above-noted findings utilizing: (i) a large sample studied over an extended time interval (ii) absolute standards for 'good' and 'poor' sleep; and (iii) a formal statistical methodology to assess temporal patterning and the association of time in bed with bout duration of poor or average sleep. Thirty-three subjects with insomnia and 33 good sleepers completed sleep diaries over the course of 110 days. It was found that subjects with insomnia (compared to good sleepers) had more poor nights (e.g. about 39 versus 7% of the assessed nights), a higher probability of a having a poor night on any given occasion (60% greater probability than good sleepers) and more consecutive nights of poor sleep between good sleep nights (median bout duration of approximately three versus one night). Lastly, it was found that (as would be predicted by both the Spielman model and the two-process model) time in bed moderated bout duration in the insomnia group. That is, longer times in bed were associated with longer bouts of poor sleep. PMID:24730977

Perlis, Michael L; Zee, Jarcy; Swinkels, Cindy; Kloss, Jacqueline; Morgan, Kevin; David, Beverly; Morales, Knashawn

2014-10-01

64

Pattern-level temporal difference learning, data fusion, and chess  

NASA Astrophysics Data System (ADS)

Our research group is using chess as a vehicle for studying the fusion of adaptation, multiple representation, and search technologies for real-time decision making. Chess systems like Deep Blue have achieved Grandmaster chess play with a brute-force search of the game tree and human- supplied information, like piece-values and opening books. However, subtle aspects of chess, including positional features and advanced concepts, are not capable of being represented or processed efficiently with the standard method. Since 1989, Morph I-III have exhibited more autonomy and learning ability than traditional chess programs in `adaptive pattern-oriented chess'. Like its predecessors, Morph IV is a reinforcement learner, but it also uses a new technique we call pattern-level TD and Q-learning to mathematically map the state space and effectively learn to classify situations. Its three knowledge sources include two traditional ones: material and a piece-square table, and a new method called Distance. These are combined using a simple genetic algorithm and a decision tree. This paper shows the effectiveness of fusing knowledge to replace search in real-time situations, since an agent which combines all sources is capable of consistently beating an agent which employs any of the individual knowledge sources. Surprisingly, the pattern-level TD agent is slightly superior to the pattern-level Q-learning agent, despite the fact that the Q-learning agent updates more Q-values on each temporal step.

Levinson, Robert; Weber, Ryan J.

2000-04-01

65

Temporal and acoustic characteristics of Greek vowels produced by adults with cerebral palsy  

NASA Astrophysics Data System (ADS)

The present investigation examined the temporal and spectral characteristics of Greek vowels as produced by speakers with intact (NO) versus cerebral palsy affected (CP) neuromuscular systems. Six NO and six CP native speakers of Greek produced the Greek vowels [i, e, a, o, u] in the first syllable of CVCV nonsense words in a short carrier phrase. Stress could be on either the first or second syllable. There were three female and three male speakers in each group. In terms of temporal characteristics, the results showed that: vowels produced by CP speakers were longer than vowels produced by NO speakers; stressed vowels were longer than unstressed vowels; vowels produced by female speakers were longer than vowels produced by male speakers. In terms of spectral characteristics the results showed that the vowel space of the CP speakers was smaller than that of the NO speakers. This is similar to the results recently reported by Liu et al. [J. Acoust. Soc. Am. 117, 3879-3889 (2005)] for CP speakers of Mandarin. There was also a reduction of the acoustic vowel space defined by unstressed vowels, but this reduction was much more pronounced in the vowel productions of CP speakers than NO speakers.

Botinis, Antonis; Orfanidou, Ioanna; Fourakis, Marios; Fourakis, Marios

2005-09-01

66

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

PubMed

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

Krajewski, Jarek; Batliner, Anton; Golz, Martin

2009-08-01

67

Spatial and Temporal Patterns of Eastern Australia Subtropical Coral Communities  

PubMed Central

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

Dalton, Steven J.; Roff, George

2013-01-01

68

Spatial and temporal patterns of eastern Australia subtropical coral communities.  

PubMed

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

Dalton, Steven J; Roff, George

2013-01-01

69

Behavioral/Systems/Cognitive Temporal-Pattern Recognition by Single Neurons in a  

E-print Network

Behavioral/Systems/Cognitive Temporal-Pattern Recognition by Single Neurons in a Sensory Pathway- tions devoted to precise temporal coding (Carr, 1993; Carr and Soares, 2002). In addition to conveying

70

A Temporal Pattern Mining Approach for Classifying Electronic Health Record Data  

PubMed Central

We study the problem of learning classification models from complex multivariate temporal data encountered in electronic health record systems. The challenge is to define a good set of features that are able to represent well the temporal aspect of the data. Our method relies on temporal abstractions and temporal pattern mining to extract the classification features. Temporal pattern mining usually returns a large number of temporal patterns, most of which may be irrelevant to the classification task. To address this problem, we present the Minimal Predictive Temporal Patterns framework to generate a small set of predictive and non-spurious patterns. We apply our approach to the real-world clinical task of predicting patients who are at risk of developing heparin induced thrombocytopenia. The results demonstrate the benefit of our approach in efficiently learning accurate classifiers, which is a key step for developing intelligent clinical monitoring systems.

Batal, Iyad; Valizadegan, Hamed; Cooper, Gregory F.; Hauskrecht, Milos

2013-01-01

71

Spatio-temporal foraging patterns of a giant zooplanktivore, the leatherback turtle Sabrina Fossette a,  

E-print Network

Spatio-temporal foraging patterns of a giant zooplanktivore, the leatherback turtle Sabrina Keywords: Leatherback turtle Migration strategy Foraging behavior Zooplankton distribution Diving pattern-temporal foraging patterns in 21 leatherback turtles during their pluri-annual migration in the Northern Atlantic

Hays, Graeme

72

Statistical methods for investigating quiescence and other temporal seismicity patterns  

USGS Publications Warehouse

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.

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

1988-01-01

73

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

PubMed Central

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

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

2012-01-01

74

Spatio-temporal correlation of vegetation and temperature patterns  

NASA Astrophysics Data System (ADS)

Temperature is one of the variables largely influencing vegetation species distributions (biogeographical regions) and plant development (phenological cycle). Anomalies in temperature regional patterns and in microclimate conditions induce modifications in vegetation cover phenology; in particular in European regions, the responsiveness of vegetation to temperature increase is greater in warmer Mediterranean countries. In order to assess the spatial arrangement and the temporal variability of vegetation and temperature patterns in a typical Mediterranean environment, we investigated monthly NDVI-AVHRR and temperature time series over Southern Italy, core of Mediterranean Basin. Temperature data, obtained from 35 meteoclimatic stations, were rasterized by adopting a combined deterministic-stochastic procedure we suitably implemented for the investigated region in order to obtain spatial data comparable with NDVI maps. For the period 1996-1998, monthly MVC data were clusterized on annual basis by means of a classification procedure to aggregate areas with similar phenological cycles. The same procedure was adopted to jointly evaluate temperature and vegetation profiles and identify areas having similar phenological and temperature patterns. The comparison of the identified clusters showed that the classification obtained with and without temperature profiles are very similar enhancing the strong role of this variable in vegetation development. Some exceptions in the cluster arrangement are due to local anomalies in vegetation distribution, such as forest fires. In order to spatially analyze such a dependence, we also elaborated a time correlation map for each year and we found that the correlation patterns are persistent on the year basis and generally follow the land cover distributions. The correlation values are very high and positive for the forested mountainous areas (R>0.8), whereas they are negative for plan coastal areas (R<-0.8). Low correlation values (R= -0.4/0.4) were found for the transitional zones and agricultural areas mainly dominated by irrigated herbaceous cultivations. On average, in southern Italy the analysis showed a strong dependence of NDVI and temperature profiles during the spring and summer time (greening period) and a reduced responsiveness in autumn when precipitations control the vegetation recovery after the water shortage period.

Coppola, R.; D'Emilio, M.; Imbrenda, V.; Lanfredi, M.; Macchiato, M.; Simoniello, T.

2010-05-01

75

Temporal Patterns of Diversification across Global Cichlid Biodiversity (Acanthomorpha: Cichlidae)  

PubMed Central

The contrasting distribution of species diversity across the major lineages of cichlids makes them an ideal group for investigating macroevolutionary processes. In this study, we investigate whether different rates of diversification may explain the disparity in species richness across cichlid lineages globally. We present the most taxonomically robust time-calibrated hypothesis of cichlid evolutionary relationships to date. We then utilize this temporal framework to investigate whether both species-rich and depauperate lineages are associated with rapid shifts in diversification rates and if exceptional species richness can be explained by clade age alone. A single significant rapid rate shift increase is detected within the evolutionary history of the African subfamily Pseudocrenilabrinae, which includes the haplochromins of the East African Great Lakes. Several lineages from the subfamilies Pseudocrenilabrinae (Australotilapiini, Oreochromini) and Cichlinae (Heroini) exhibit exceptional species richness given their clade age, a net rate of diversification, and relative rates of extinction, indicating that clade age alone is not a sufficient explanation for their increased diversity. Our results indicate that the Neotropical Cichlinae includes lineages that have not experienced a significant rapid burst in diversification when compared to certain African lineages (rift lake). Neotropical cichlids have remained comparatively understudied with regard to macroevolutionary patterns relative to African lineages, and our results indicate that of Neotropical lineages, the tribe Heroini may have an elevated rate of diversification in contrast to other Neotropical cichlids. These findings provide insight into our understanding of the diversification patterns across taxonomically disparate lineages in this diverse clade of freshwater fishes and one of the most species-rich families of vertebrates. PMID:23990936

McMahan, Caleb D.; Chakrabarty, Prosanta; Sparks, John S.; Smith, Wm. Leo; Davis, Matthew P.

2013-01-01

76

Horizontal spatial and temporal distribution patterns of nearshore larval fish assemblages at a temperate rocky shore  

E-print Network

Horizontal spatial and temporal distribution patterns of nearshore larval fish assemblages distribution patterns of larval fish assemblages and their temporal dynamics near a rocky reef at depths shallower than 13 m (inshore) and at two miles (3.70 km) from shore (offshore), as well as along transects

Borges, Rita

77

Spatial and temporal climate forcing patterns from Amazon fires  

NASA Astrophysics Data System (ADS)

Fires influence climate through numerous pathways, including emissions of greenhouse gases and aerosols, surface albedo perturbation, and changes in cloud and water vapor content via altered evapotranspiration. Here, we assess temporal and spatial patterns of climate forcing terms from fires in the Amazon region. Randerson et al. (2006) showed that surface albedo change provides the dominant radiative forcing term for boreal forest fires, integrated over multi-decadal timescales. This is a consequence of springtime snow blanketing over the burned area, a process absent from tropical regions. In the immediate aftermath of Amazon fire, aerosol forcing dominates, as in the boreal case, with large reductions in surface insolation and top-of-atmosphere forcing that depends on cloud cover and vertical aerosol distribution. On decadal timescales, greenhouse warming supersedes the albedo cooling effect, opposite the boreal case. Long-term albedo forcing depends on whether burned land is allowed to return to forest or is maintained for agricultural purposes. With respect to regional climate influence, however, the spatial distribution of forcing is critical. Albedo and aerosol/cloud/vapor effects operate locally and regionally, whereas greenhouse gases mix globally. We explore impacts of fire aerosol and albedo forcing on Amazon surface temperature and precipitation, applying the NCAR Community Atmosphere Model and emissions from the Global Fire Emissions Database (GFEDv2). One goal of this assessment is to identify whether fire-induced climate changes promote more, or less, efficient use of fire. We assess the strength of this feedback on both seasonal and multi-annual timescales. Finally, we compare influences of fires ignited during the early and late phases of the dry season.

Flanner, M. G.; Mahowald, N. M.; Randerson, J. T.; Kloster, S.

2008-12-01

78

Spatial and temporal pattern of pesticides in the global atmosphere.  

PubMed

As part of the Global Atmospheric Passive Sampling (GAPS) study, XAD-resin based passive samplers are being deployed for consecutive one-year periods at numerous sites on all seven continents to determine annually averaged concentrations of persistent organic pollutants. Concentrations of banned organochlorine pesticides as well as a number of current-use pesticides in samples from the first four years, roughly coinciding with 2005, 2006, 2007 and 2008, show distinct spatial and temporal patterns. Whereas organochlorine pesticides such as alpha- and gamma-hexachlorocyclohexane, endosulfans, DDT and its metabolites, and chlordane-related compounds tend to be more prevalent in developing countries, especially in Asia, concentrations of current use pesticides such as trifluralin and chlorothalonil are often higher in Europe and North America. Based on 15 stations with four years of data, levels of hexachlorobenzene, hexachlorocyclohexanes and chlordanes decline in most world regions, which may reflect decreased usage in response to global restrictions. Levels of organochlorine pesticides in India, however, remain exceptionally high. Concentrations of alpha-endosulfan, chlorothalonil and trifluralin decrease in the European atmosphere during the sampling periods, indicating reduced usage. Consistently high alpha/gamma-HCH ratios in air samples from high Northern latitudes confirm that re-volatilization from the Arctic Ocean is a significant source of alpha-HCH. The highest levels of alpha-HCH, however, occur in conjunction with high gamma-HCH levels, suggesting that lindane use is now the major source of alpha-HCH to the global atmosphere. Although a wide variety of sampling site types aids in characterizing the entire global concentration variability of a pesticide, it also increases greatly the number of sites required for a robust regional differentiation. PMID:20697628

Shunthirasingham, Chubashini; Oyiliagu, Catherine E; Cao, Xiaoshu; Gouin, Todd; Wania, Frank; Lee, Sum-Chi; Pozo, Karla; Harner, Tom; Muir, Derek C G

2010-09-01

79

Spatial and temporal patterns of subtidal and intertidal crabs excursions  

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

80

Acoustics and sociolinguistics: Patterns of communication in hearing impairing classrooms  

NASA Astrophysics Data System (ADS)

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.

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

2005-04-01

81

Acoustic Processing of Temporally Modulated Sounds in Infants: Evidence from a Combined Near-Infrared Spectroscopy and EEG Study  

PubMed Central

Speech perception requires rapid extraction of the linguistic content from the acoustic signal. The ability to efficiently process rapid changes in auditory information is important for decoding speech and thereby crucial during language acquisition. Investigating functional networks of speech perception in infancy might elucidate neuronal ensembles supporting perceptual abilities that gate language acquisition. Interhemispheric specializations for language have been demonstrated in infants. How these asymmetries are shaped by basic temporal acoustic properties is under debate. We recently provided evidence that newborns process non-linguistic sounds sharing temporal features with language in a differential and lateralized fashion. The present study used the same material while measuring brain responses of 6 and 3?month old infants using simultaneous recordings of electroencephalography (EEG) and near-infrared spectroscopy (NIRS). NIRS reveals that the lateralization observed in newborns remains constant over the first months of life. While fast acoustic modulations elicit bilateral neuronal activations, slow modulations lead to right-lateralized responses. Additionally, auditory-evoked potentials and oscillatory EEG responses show differential responses for fast and slow modulations indicating a sensitivity for temporal acoustic variations. Oscillatory responses reveal an effect of development, that is, 6 but not 3?month old infants show stronger theta-band desynchronization for slowly modulated sounds. Whether this developmental effect is due to increasing fine-grained perception for spectrotemporal sounds in general remains speculative. Our findings support the notion that a more general specialization for acoustic properties can be considered the basis for lateralization of speech perception. The results show that concurrent assessment of vascular based imaging and electrophysiological responses have great potential in the research on language acquisition. PMID:21716574

Telkemeyer, Silke; Rossi, Sonja; Nierhaus, Till; Steinbrink, Jens; Obrig, Hellmuth; Wartenburger, Isabell

2010-01-01

82

DUPLEX PERCEPTION OF ACOUSTIC PATTERNS AS SPEECH AND NONSPEECH Alvin M. Liberman+ and David S. Isenberg++  

E-print Network

in several ways. At the level of speech perception, it might appear as a distinctive mode (or subsystemDUPLEX PERCEPTION OF ACOUSTIC PATTERNS AS SPEECH AND NONSPEECH Alvin M. Liberman+ and David S separately to the two ears, listeners fuse them into a coherent phonetic percept, while a1 so perceiving one

83

Spatial and temporal patterns in erosion and deposition in the York River, Chesapeake Bay, VA  

NASA Astrophysics Data System (ADS)

Seasonal patterns of seabed erosion and deposition in a dynamic estuarine environment, the York River (USA), are examined through acoustic studies and seabed sampling to identify the dominant environmental controls on sediment mobility. Areas near Clay Bank in the York River were surveyed monthly using a dual-frequency sonar for a 12 month period. In addition, six stations within these areas were sampled during the surveys. Strong spatial and temporal variations of a soft mud layer were identified, providing new insight to recurring seasonal and spatial patterns in deposition and erosion in the middle reaches of the York River estuary. Sub-bottom data indicated maximum thickness (5-22 cm ± 4 cm) of the soft mud layer during spring and winter from April 2008 through March 2009. Minimum thicknesses (1-12 cm ± 4 cm) of the soft mud layer were observed during summer and fall. Maximum thickness coincided with the occurrence of the secondary turbidity maximum near Clay Bank in the York River. Spatial variations in the soft-mud layer thickness were also identified between and within the York River secondary channel, the inactive oyster reef area, the south west flank of the main channel, and the main channel. The upriver secondary channel, the south west channel flank, and the main channel areas were physically dominated. The downriver secondary channel area was biologically dominated and the inactive oyster reef area reflected both physical and biological processes. Water content trends showed no correlation with seabed stability in this area. Observed changes in soft mud thicknesses are interpreted to result from both biological and physical factors, which vary markedly between winter/spring and summer/fall seasons, and among the different environments of the estuary's channel.

Rodríguez-Calderón, Cielomar; Kuehl, Steven A.

2013-01-01

84

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

E-print Network

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 ...

Harms, Michael Patrick, 1972-

2002-01-01

85

Temporal motifs reveal homophily, gender-specific patterns, and group talk in call sequences.  

PubMed

Recent studies on electronic communication records have shown that human communication has complex temporal structure. We study how communication patterns that involve multiple individuals are affected by attributes such as sex and age. To this end, we represent the communication records as a colored temporal network where node color is used to represent individuals' attributes, and identify patterns known as temporal motifs. We then construct a null model for the occurrence of temporal motifs that takes into account the interaction frequencies and connectivity between nodes of different colors. This null model allows us to detect significant patterns in call sequences that cannot be observed in a static network that uses interaction frequencies as link weights. We find sex-related differences in communication patterns in a large dataset of mobile phone records and show the existence of temporal homophily, the tendency of similar individuals to participate in communication patterns beyond what would be expected on the basis of their average interaction frequencies. We also show that temporal patterns differ between dense and sparse neighborhoods in the network. Because also this result is independent of interaction frequencies, it can be seen as an extension of Granovetter's hypothesis to temporal networks. PMID:24145424

Kovanen, Lauri; Kaski, Kimmo; Kertész, János; Saramäki, Jari

2013-11-01

86

Recognition of Acoustic Emission Patterns from Mixed Mode Wood Fracture.  

NASA Astrophysics Data System (ADS)

Automatic, reactive control of wood drying to maximize drying rate and minimize drying defects would be possible if the development of internal stress associated with micro and macro failure processes due to shrinkage could be detected in real time. Assuming that AE signals due to micro and macro failures during wood fracture testing are the same or similar to signals produced by drying stresses and check formation, it was decided to collect AE signals during wood fracture testing under the type of conditions of moisture content and temperature which might be found during the kiln drying process, and investigate if they may be useful in automatic, reactive kiln control. In particular, it was intended to determine if there were AE patterns associated with specific load levels leading to wood fracture which could give early warning of impending failures. AE signals and load were recorded during fracture testing of Pinus ponderosa and Quercus kelloggii. Single -edge notch tension specimens in the TL orientation were tested in mixed mode (Modes I and II) to determine if there are AE patterns associated with particular loading stages. Tests were made at three levels of temperature--20, 40, and 60 ^circC--and two levels of moisture content--12 and 18%. It was found that (a) maximum event rate increased with increasing load to maximum load and beyond, (b) temperature had a significant effect on number of events to maximum load, (c) moisture content had a significant effect on number of events to conclusion of test, (d) AE signal patterns could be successfully classified by cluster analysis and canonical discriminant analysis, (e) temperature, moisture content, and their interaction had a significant effect on features of AE signal patterns. The AE signal patterns showed very little relationship to stress levels in wood fracture. Pattern recognition of single AE signals therefore does not hold much promise for application to monitoring and control of the kiln drying process. Recognition of key features such as maximum event rate and their critical values therefore appears to be the more useful approach.

Lee, Shih-Hao

87

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

E-print Network

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 ...

Olson, Karen L.

88

A Pulse-Type Hardware Neural Network with STDP for Memory of Temporal Sequences Patterns  

NASA Astrophysics Data System (ADS)

In recent years, synaptic plasticity, which is dependent on the order and time interval of pre- and post-synaptic spikes (STDP: spike-timing-dependent synaptic plasticity), has been observed by physiological experiments. There is a type of STDP, which is characterized by a symmetric time window (a Mexican-hat-type window). It has been reported that a Mexican-hat window participates in an inhibitory interneuron. In this study, we investigate a memory of temporal sequences patterns using P-HNN (Pulse-type Hardware Neural Network) with STDP (Mexican-hat time window). To be more specific, we propose the construction of a P-HNN with STDP. In addition, we examine the temporal sequences patterns which were memorized by using a P-HNN with STDP. As a result, we show that a P-HNN with STDP memorize temporal sequences output voltage patterns which obeyed the temporal sequences input current patterns.

Shimizu, Ryo; Saeki, Katsutoshi; Sekine, Yoshifumi

89

Larval amphibians learn to match antipredator response intensity to temporal patterns of risk  

Microsoft Academic Search

The importance of temporal variability in risk has recently come to the forefront of research examining the behavioral ecology of predator--prey relationships. Temporal variability has been known to drive patterns of behavioral responses associated with foraging, reproduction, and territorial defense of prey animals. However, it is unknown if such behavioral responses are a result of selective depredation, which leads to

Maud C. O. Ferrari; François Messier; Douglas P. Chivers

2008-01-01

90

Enriching Multivariate Temporal Patterns with Context Information to Support Classification  

E-print Network

task, the first step enables the user to better match his or her mental model of the temporal process is controlling a chemical production process, a user interacting with a technical device, a medic administering a drug to a patient ­ in all these cases instantaneous information does not help to differentiate between

Berthold, Michael R.

91

Spatial and temporal patterns of predation on seeds of the surfgrass Phyllospadix torreyi  

Microsoft Academic Search

Spatial and temporal patterns of predation on seeds of the seagrass Phyllospadix torreyi S. Watson were quantified at four sites near Santa Barbara, California, USA. Over a period of four flowering seasons during\\u000a 1995 to 1998, monthly patterns of seed fall and intensity of seed predation were similar among sites, but were temporally\\u000a quite variable. Abundance of dispersed seeds varied

S. J. Holbrook; D. C. Reed; K. Hansen; C. A. Blanchette

2000-01-01

92

Mining spatio-temporal patterns in object mobility databases  

Microsoft Academic Search

With the increasing use of wireless communication devices and the ability to track people and objects cheaply and easily,\\u000a the amount of spatio-temporal data is growing substantially. Many of these applications cannot easily locate the exact position\\u000a of objects, but they can determine the region in which each object is contained. Furthermore, the regions are fixed and may\\u000a vary greatly

Florian Verhein; Sanjay Chawla

2008-01-01

93

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

PubMed

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

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

2013-11-01

94

Experimental quiescent drifting dusty plasmas and temporal dust acoustic wave growth  

SciTech Connect

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.

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

95

DAILY PATTERNS IN THE ACTIVITIES OF SWORDFISH, X/PH/AS GLAD/US, OBSERVED BY ACOUSTIC TELEMETRY  

E-print Network

DAILY PATTERNS IN THE ACTIVITIES OF SWORDFISH, X/PH/AS GLAD/US, OBSERVED BY ACOUSTIC TELEMETRY studied using acoustic telemetry. Five swordfish in the Pacific and one in the Atlantic were tagged aspects of their behavior can be readily examined by telemetry from attached sensors. Xiphias gladius

96

Patterns of diel vertical migration of zooplankton in acoustic Doppler velocity and backscatter data on the Newfoundland Shelf  

Microsoft Academic Search

Backscatter data from moored acoustic Doppler current profilers (ADCPs) are analysed to quantify the diel vertical migration patterns of zooplankton on the Newfoundland Shelf, Canada. Data from 11 moorings provide long time series (~100 days each) for in-depth statistical analysis. For one deployment, dry weight measurements of zoo- plankton are used to calibrate the acoustic backscatter. Quantification methods are developed

Nicholas R. Record; Brad de Young

2006-01-01

97

Spatial and temporal patterns of resource heterogeneity and foraging behavior  

E-print Network

Movement patterns reflect how an animal responds to aphics. variations in resource distribution, with important implications for management and conservation concerns. Foraging paths and food items provide a unique opportunity to relate movement...

Baum, Kristen Anne

2012-06-07

98

Spatio-temporal patterns of bacteria caused by collective motion  

NASA Astrophysics Data System (ADS)

In incubation experiments on bacterial colonies of Proteus mirabilis, collective motion of bacteria is found to generate macroscopic turbulent patterns on the surface of agar media. We propose a mathematical model to describe the time evolution of the positional and directional distributions of motile bacteria in such systems, and investigate this model both numerically and analytically. It is shown that as the average density of bacteria increases, nonuniform swarming patterns emerge from a uniform stationary state. For a sufficient large density, we find that spiral patterns are caused by interactions between the local bacteria densities and the rotational mode of the collective motion. Unidirectional spiral patterns similar to those observed in experiments appear in the case in which the equilibrium directional distribution is asymmetric.

Kitsunezaki, So

2006-04-01

99

Improvement of surface acoustic wave gas sensor response time using neural-network pattern recognition  

Microsoft Academic Search

Surface acoustic wave (SAW) gas-sensor signal processing may allow first, detection of gases, secondly, their identification and thirdly, if possible, their quantification. for a few years now, pattern-recognition techniques using artificial neural networks have been applied to sensor arrays with promising results. Nevertheless, data sets needed for these techniques, are always built with well-established and stable sensor responses. Sometimes, the

Christophe Bordieu; Jacques Pistre´

1995-01-01

100

Temporal-pattern recognition by single neurons in a sensory pathway devoted to social communication behavior  

PubMed Central

Sensory systems often encode stimulus information into the temporal pattern of action potential activity. However, little is known about how the information contained within these patterns is extracted by postsynaptic neurons. Similar to temporal coding by sensory neurons, social information in mormyrid fish is encoded into the temporal patterning of an electric organ discharge (EOD). In the current study, sensitivity to temporal patterns of electrosensory stimuli was found to arise within the midbrain posterior exterolateral nucleus (ELp). Whole-cell patch recordings from ELp neurons in vivo revealed three patterns of interpulse interval (IPI) tuning: low-pass neurons tuned to long intervals, high-pass neurons tuned to short intervals and band-pass neurons tuned to intermediate intervals. Many neurons within each class also responded preferentially to either increasing or decreasing IPIs. Playback of electric signaling patterns recorded from freely behaving fish revealed that the IPI and direction tuning of ELp neurons resulted in selective responses to particular social communication displays characterized by distinct IPI patterns. The postsynaptic potential responses of many neurons indicated a combination of excitatory and inhibitory synaptic input, and the IPI tuning of ELp neurons was directly related to rate-dependent changes in the direction and amplitude of postsynaptic potentials. These results suggest that differences in the dynamics of short-term synaptic plasticity in excitatory and inhibitory pathways may tune central sensory neurons to particular temporal patterns of presynaptic activity. This may represent a general mechanism for the processing of behaviorally-relevant stimulus information encoded into temporal patterns of activity by sensory neurons. PMID:19641105

Carlson, Bruce A.

2010-01-01

101

Analysing spatio-temporal pattern of changing farmland in China's arid zone  

Microsoft Academic Search

Multi-temporal imagery has been used for landuse and land cover change detection since the very early stage of remote sensing technology. As large amount of remotely sensed data have been collected, historical land cover changes and change patterns can be reconstructed by a time series recorded by images. This paper reports a study on the methodology for quantifying spatial pattern

Qiming Zhou; Bo Sun

2008-01-01

102

Temporal consistency in the spatial pattern of seed predation across a forest old field edge  

E-print Network

field in low predation years. Seed removal rate covaried with spatial pattern of Peromyscus leucopus­581-7141) Received 20 March 2001; accepted in revised form 5 December 2001 Key words: Edge effects, Peromyscus leucopus, Temporal pattern, Tree regeneration Abstract Seed predation is an important factor in determining

103

Mining Probabilistic Frequent Spatio-Temporal Sequential Patterns with Gap Constraints from Uncertain Databases  

E-print Network

Mining Probabilistic Frequent Spatio-Temporal Sequential Patterns with Gap Constraints from of Computing Science Simon Fraser University BC V5A 1S6, Canada Email: jpei@cs.sfu.ca Abstract in much interest in itemset mining for uncertain transaction databases. In this paper, we focus on pattern

Pei, Jian

104

Spatio-temporal patterns of road traffic noise pollution in Karachi, Pakistan  

Microsoft Academic Search

We studied the spatial and temporal patterns of noise exposure due to road traffic in Karachi City, Pakistan, and found that levels of noise were generally higher during mornings and evenings because of the commuting pattern of Karachi residents. This study found the average value of noise levels to be over 66dB, which could cause serious annoyance according to the

Mohammed Raza Mehdi; Minho Kim; Jeong Chang Seong; Mudassar Hassan Arsalan

2011-01-01

105

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

Microsoft Academic Search

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

Gerald S. Pollack; Ronald R. Hoy

1979-01-01

106

Conflict, Trust, and Effectiveness in Teams Performing Complex Tasks: A Study of Temporal Patterns  

Microsoft Academic Search

In this study we analyze the evolution of intra-team conflict and trust in teams that perform complex tasks. Using a longitudinal research design with six time intervals over a period of ten months, we collected data on 41 teams. Our findings suggest the existence of two distinct temporal patterns. One pattern develops in a stable manner and is characterized by

Anneloes M. L. Raes; Mariëlle G. Heijltjes; Ursula Glunk; Robert A. Roe

2006-01-01

107

TEMPORAL AND SPATIAL PATTERNS OF NEARSHORE DISTRIBUTION AND ABUNDANCE OF THE PELAGIC FISHES  

E-print Network

TEMPORAL AND SPATIAL PATTERNS OF NEARSHORE DISTRIBUTION AND ABUNDANCE OF THE PELAGIC FISHES OFF SAN). These sources have provided general information on com- position, distribution, and behavior of the offshore pattern exhibited by the common species in the assemblage involved a marked shift in depth over adiel

108

Temporal patterns in air pollution and hospital admissions.  

PubMed

A 6-year data set of daily counts of admissions to 79 acute care hospitals in Southern Ontario was analyzed in relation to concurrent measurements of air pollution and weather pooled over the same regions, using progressively more sophisticated statistical techniques. The diagnoses studied included a group of respiratory causes and two control diagnoses: accidents and gastrointestinal causes. The 6-year period (1979-1985) was subdivided into six 2-month "seasons" and the area of study was divided into three subregions. Bivariate correlations were found to be significant more often than expected due to chance for all three admissions variables, but accounting for the temporal variation within the 60-day seasons greatly reduced the significance of the control diagnoses. Twenty-four-hour averages for air quality were found to yield more significant associations than peak hourly concentrations. July-August was the only period not having important within-season temporal trends and also had the lowest daily counts for respiratory admissions. Based on a model which accounted for serial correlation, SO2, ozone, and sulfate aerosol were found to be significant predictors of respiratory admissions during July-August. Using cumulative lags increased the magnitude of the estimated response to about 20% of summer respiratory admissions, but no consistent relationships were found which could identify the "responsible" pollutant(s) with certainty. Average pollutant concentrations were generally within U.S. ambient standards. PMID:1464290

Lipfert, F W; Hammerstrom, T

1992-12-01

109

Avian Incubation Patterns Reflect Temporal Changes in Developing Clutches  

PubMed Central

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

2013-01-01

110

Temporal patterns in air pollution and hospital admissions  

SciTech Connect

A 6-year data set of daily counts of admissions to 79 acute care hospitals in Southern Ontario was analyzed in relation to concurrent measurements of air pollution and weather pooled over the same regions, using progressively more sophisticated statistical techniques. The diagnoses studied included a group of respiratory causes and two control diagnoses: accidents and gastrointestinal causes. The 6-year period (1979-1985) was subdivided into six 2-month seasons and the area of study was divided into three subregions. Bivariate correlations were found to be significant more often than expected due to chance for all three admissions variables, but accounting for the temporal variation within the 60-day seasons greatly reduced the significance of the control diagnoses. Twenty-four-hour averages for air quality were found to yield more significant associations than peak hourly concentrations. July-August was the only period not having important within-season temporal trends and also had the lowest daily counts for respiratory admissions. Based on a model which accounted for serial correlation, SO2, ozone, and sulfate aerosol were found to be significant predictors of respiratory admissions during July-August. Using cumulative lags increased the magnitude of the estimated response to about 20% of summer respiratory admissions, but no consistent relationships were found which could identify the responsible pollutant(s) with certainty. Average pollutant concentrations were generally within U.S. ambient standards.

Lipfert, F.W.; Hammerstrom, T. (Roth Associates, Inc., Rockville, MD (United States))

1992-12-01

111

X-ray diffraction pattern of a Gulyaev-Bleustein surface acoustic wave in grazing geometry  

SciTech Connect

The X ray diffraction pattern of a Gulyaev-Bleustein surface acoustic wave (SAW) under grazing angles of incidence in noncoplanar symmetric Laue geometry has been considered. It is supposed that the propagation direction of an SAW makes a small angle with the diffraction vector. It is shown that small deviations from the Bragg angle ({approx}0.01'' induced by the SAW and do not affect the reflection coefficient lead to the formation of diffraction satellites both in the cases of standing and traveling SAWs. It has been established that the recorded diffraction pattern, which is a time-averaged intensity distribution, has characteristic profiles for odd and even satellites.

Levonyan, L. V., E-mail: gurgen@iapp.sci.am; Khachaturyan, G. K. [Academy of Sciences of Armenia, Institute of Applied Physics Problems (Armenia)

2006-12-15

112

Statistical methods for investigating quiescence and other temporal seismicity patterns  

Microsoft Academic Search

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.

Mark V. Matthews; Paul A. Reasenberg

1988-01-01

113

Life between clocks: daily temporal patterns of human chronotypes.  

PubMed

Human behavior shows large interindividual variation in temporal organization. Extreme "larks" wake up when extreme "owls" fall asleep. These chronotypes are attributed to differences in the circadian clock, and in animals, the genetic basis of similar phenotypic differences is well established. To better understand the genetic basis of temporal organization in humans, the authors developed a questionnaire to document individual sleep times, self-reported light exposure, and self-assessed chronotype, considering work and free days separately. This report summarizes the results of 500 questionnaires completed in a pilot study individual sleep times show large differences between work and free days, except for extreme early types. During the workweek, late chronotypes accumulate considerable sleep debt, for which they compensate on free days by lengthening their sleep by several hours. For all chronotypes, the amount of time spent outdoors in broad daylight significantly affects the timing of sleep: Increased self-reported light exposure advances sleep. The timing of self-selected sleep is multifactorial, including genetic disposition, sleep debt accumulated on workdays, and light exposure. Thus, accurate assessment of genetic chronotypes has to incorporate all of these parameters. The dependence of human chronotype on light, that is, on the amplitude of the light:dark signal, follows the known characteristics of circadian systems in all other experimental organisms. Our results predict that the timing of sleep has changed during industrialization and that a majority of humans are sleep deprived during the workweek. The implications are far ranging concerning learning, memory, vigilance, performance, and quality of life. PMID:12568247

Roenneberg, Till; Wirz-Justice, Anna; Merrow, Martha

2003-02-01

114

Plasticity of temporal pattern codes for vocalization stimuli in primary auditory cortex.  

PubMed

It has been suggested that "call-selective" neurons may play an important role in the encoding of vocalizations in primary auditory cortex (A1). For example, marmoset A1 neurons often respond more vigorously to natural than to time-reversed twitter calls, although the spectral energy distribution in the natural and time-reversed signals is the same. Neurons recorded in cat A1, in contrast, showed no such selectivity for natural marmoset calls. To investigate whether call selectivity in A1 can arise purely as a result of auditory experience, we recorded responses to marmoset calls in A1 of naive ferrets, as well as in ferrets that had been trained to recognize these natural marmoset calls. We found that training did not induce call selectivity for the trained vocalizations in A1. However, although ferret A1 neurons were not call selective, they efficiently represented the vocalizations through temporal pattern codes, and trained animals recognized marmoset twitters with a high degree of accuracy. These temporal patterns needed to be analyzed at timescales of 10-50 ms to ensure efficient decoding. Training led to a substantial increase in the amount of information transmitted by these temporal discharge patterns, but the fundamental nature of the temporal pattern code remained unaltered. These results emphasize the importance of temporal discharge patterns and cast doubt on the functional significance of call-selective neurons in the processing of animal communication sounds at the level of A1. PMID:16672651

Schnupp, Jan W H; Hall, Thomas M; Kokelaar, Rory F; Ahmed, Bashir

2006-05-01

115

Effective beam pattern of the Blainville's beaked whale (Mesoplodon densirostris) and implications for passive acoustic monitoring.  

PubMed

The presence of beaked whales in mass-strandings coincident with navy maneuvers has prompted the development of methods to detect these cryptic animals. Blainville's beaked whales, Mesoplodon densirostris, produce distinctive echolocation clicks during long foraging dives making passive acoustic detection a possibility. However, performance of passive acoustic monitoring depends upon the source level, beam pattern, and clicking behavior of the whales. In this study, clicks recorded from Digital acoustic Tags (DTags) attached to four M. densirostris were linked to simultaneous recordings from an 82-hydrophone bottom-mounted array to derive the source level and beam pattern of the clicks, as steps towards estimating their detectability. The mean estimated on-axis apparent source level for the four whales was 201 dBrms97. The mean 3?dB beamwidth and directivity index, estimated from sequences of clicks directed towards the far-field hydrophones, were 13° and 23?dB, respectively. While searching for prey, Blainville's beaked whales scan their heads horizontally at a mean rate of 3.6°/s over an angular range of some +/-10°. Thus, while the DI indicates a narrow beam, the area of ensonification over a complete foraging dive is large given the combined effects of body and head movements associated with foraging. PMID:23464046

Shaffer, Jessica Ward; Moretti, David; Jarvis, Susan; Tyack, Peter; Johnson, Mark

2013-03-01

116

Processes driving temporal dynamics in the nested pattern of waterbird communities  

NASA Astrophysics Data System (ADS)

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.

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

2010-03-01

117

Learning Temporal Patterns of Risk in a Predator-Diverse Environment  

PubMed Central

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

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

2012-01-01

118

Temporal patterns of tick-borne granulocytic anaplasmosis in California.  

PubMed

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

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

2011-06-01

119

Spatial and temporal patterns of nitrogen deposition in China  

NASA Astrophysics Data System (ADS)

Anthropogenic nitrous pollutant emission in China significantly increased during the last decades, which also contributed to the accelerated N deposition. In order to characterize spatial pattern of nitrogen deposition, we employed kriging technique to interpolate sampling data of precipitation chemistry and ambient air concentration from site-network observation over China. Due to the range of national-scale measurements, the estimation of wet deposition in China was limited to aqueous NO3- and NH4+, while ambient NO2 was the only species involved in the predicted dry deposition fluxes. To obtain wet deposition fluxes, precipitation concentration was multiplied by 30-year mean precipitation amounts with a resolution of 0.5 0.5 degree, and dry deposition fluxes were products of the interpolated ambient NO2 concentration and deposition velocity modeled for the main vegetation types in China. The total deposition rates of wet and dry deposition peaked over the central south China, with maximum values of 64.81 kg N·ha-1·yr-1, and an average value of 19.08 kg N·ha-1·yr-1. With ambient NO2 concentration data spanning from the year 1990 through 2003, we detected and evaluated trends in the time series of the annual values of atmospheric NO2 concentration. Significant upward trends at 21 of 102 sites were exhibited, with median percent change of 61.45% over the period 1990-2003. In addition, spatially continuous patterns of dry deposition fluxes based on ambient NO2 measurements in two 5-year phases, 9 years apart, were carried out. And comparison of the two maps indicated the percent changes of deposition fluxes in every grid cell at national scale. On average, there was small rise of 7.66% in NO2 dry deposition during 9 years throughout China.

Lu, C.; Tian, H.

2006-05-01

120

Detecting spatial and temporal patterns of aboveground production in a tallgrass prairie using remotely sensed data  

SciTech Connect

Spatial and temporal patterns of aboveground production is a tallgrass prairie ecosystem constitute one of the important spatial components associated with ecological processes and biophysical resources (e.g. water and nutrients). This study addresses the effects of disturbance, topography, and climate on the spatial and temporal patterns of North American tallgrass prairie at a landscape level by using high resolution satellite data. Spatial heterogeneity derived from the satellite data was related to the impacts of the disturbance of fire and grazing, topographical gradient, and amount of precipitation during the growing season. The result suggests that ecological processes and biophysical resources can be quantified with high resolution satellite data for tallgrass prairie management.

Su, Haiping; Krummel, J.R. [Argonne National Lab., IL (United States); Briggs, J.M.; Knapp, A.K.; Blair, J.M. [Kansas State Univ., Manhattan, KS (United States). Div. of Biology

1996-05-01

121

Spatio-Temporal Patterns in Colonies of Rod-Shaped Bacteria  

NASA Astrophysics Data System (ADS)

In incubation experiments of bacterial colonies of Proteus Mirabilis, macroscopic spatio-temporal patterns, such as turbulent and unidirectional spiral patterns, appear in colonies. Considering only kinetic propeties of rod-shaped bacteria, we propose a phenomenological model for the directional and positional distributions. As the average density increases, homogeneous states bifurcate sub-critically into nonuniform states exhibiting localized collective motion, and spiral patterns appear for sufficiently large density. These patterns result from interactions between the local bacteria densities and the order parameter representing collective motion. Our model can be described by reduced equations using a perturbative method for large density. The unidirectionality of sprial rotation is also discussed.

Kitsunezaki, S.

122

Discrimination of Speech Stimuli Based on Neuronal Response Phase Patterns Depends on Acoustics But Not Comprehension  

PubMed Central

Speech stimuli give rise to neural activity in the listener that can be observed as waveforms using magnetoencephalography. Although waveforms vary greatly from trial to trial due to activity unrelated to the stimulus, it has been demonstrated that spoken sentences can be discriminated based on theta-band (3–7 Hz) phase patterns in single-trial response waveforms. Furthermore, manipulations of the speech signal envelope and fine structure that reduced intelligibility were found to produce correlated reductions in discrimination performance, suggesting a relationship between theta-band phase patterns and speech comprehension. This study investigates the nature of this relationship, hypothesizing that theta-band phase patterns primarily reflect cortical processing of low-frequency (<40 Hz) modulations present in the acoustic signal and required for intelligibility, rather than processing exclusively related to comprehension (e.g., lexical, syntactic, semantic). Using stimuli that are quite similar to normal spoken sentences in terms of low-frequency modulation characteristics but are unintelligible (i.e., their time-inverted counterparts), we find that discrimination performance based on theta-band phase patterns is equal for both types of stimuli. Consistent with earlier findings, we also observe that whereas theta-band phase patterns differ across stimuli, power patterns do not. We use a simulation model of the single-trial response to spoken sentence stimuli to demonstrate that phase-locked responses to low-frequency modulations of the acoustic signal can account not only for the phase but also for the power results. The simulation offers insight into the interpretation of the empirical results with respect to phase-resetting and power-enhancement models of the evoked response. PMID:20484530

Poeppel, David

2010-01-01

123

Temporal changes in the vegetation pattern in a tidal freshwater marsh  

Microsoft Academic Search

Temporal changes in vegetation patterns of Chesapeake Bay wetlands have been poorly documented. Data from a 1987 vegetation\\u000a analysis of a Chesapeake Bay tidal freshwater marsh were compared to those of a vegetation study completed in 1974. Changes\\u000a in the vegetation pattern were calculated using species importance values and a species diversity index. Comparison of the\\u000a 1987 and 1974 results

James E. Perry; Carl H. Hershner

1999-01-01

124

Sustained Emerging Spatio-Temporal Co-occurrence Pattern Mining: A Summary of Results  

Microsoft Academic Search

Sustained emerging spatio-temporal co-occurrence patterns (SECOPs) represent subsets of object-types that are increasingly located together in space and time. Discovering SECOPs is important due to many applications, e.g., predicting emerging infectious diseases, predicting defensive and offensive intent from troop movement patterns, and novel predator-prey interactions. However, mining SECOPs is computationally very expensive because the interest measures are computationally complex, datasets

Mete Celik; Shashi Shekhar; James P. Rogers; James A. Shine

2006-01-01

125

Spatio-temporal diffusion pattern and hotspot detection of dengue in Chachoengsao province, Thailand.  

PubMed

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

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

2011-01-01

126

Spatio-temporal patterns and source apportionment of coastal water pollution in eastern Hong Kong  

Microsoft Academic Search

The comprehensive application of different multivariate methods and geographic information systems (GIS) was used to evaluate the spatio-temporal patterns and source apportionment of coastal water pollution in eastern Hong Kong. Fourteen variables were surveyed at 27 sites monthly from 2000 to 2004. After data pretreatment, cluster analysis grouped the 12 months into two groups, June–September and the remaining months, and

Feng Zhou; Gordon H. Huang; Huaicheng Guo; Wei Zhang; Zejia Hao

2007-01-01

127

Complex temporal patterns of spontaneous initiation and termination of reentry in a loop of cardiac tissue  

E-print Network

of cardiac arrest and sudden death. Clinical observations and implantable cardioverter defibrillators (ICDComplex temporal patterns of spontaneous initiation and termination of reentry in a loop of cardiac loop of cardiac cells that circu- lates action potentials as well as a pacing mechanism. Physiological

Cain, John Wesley

128

Analyzing Temporal API Usage Patterns Gias Uddin, Barthelemy Dagenais, and Martin P. Robillard  

E-print Network

Analyzing Temporal API Usage Patterns Gias Uddin, Barth´el´emy Dagenais, and Martin P. Robillard}@cs.mcgill.ca Abstract--Software reuse through Application Programming Interfaces (APIs) is an integral part of software development. As developers write client programs, their understanding and usage of APIs change over time. Can

Robillard, Martin

129

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

Microsoft Academic Search

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

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

130

Spatial and temporal patterns of remotely-sensed and field-measured rainfall in southern California  

Microsoft Academic Search

Quantification of spatial and temporal patterns of rainfall is an important step toward developing regional hydrological models. However, traditionally used rain gauge data are sparse and do not always provide adequate spatial representation of rainfall. In this study, we evaluated the daily 1-degree resolution remotely-sensed atmospheric precipitation data provided by Global Precipitation Climatology Project (GPCP) as an alternative to rain

Nikolay P. Nezlin; Eric D. Stein

2005-01-01

131

ORIGINAL PAPER Temporal changes in the spatial pattern of leaf traits  

E-print Network

of individual plants changes with successional status and disturbance (Robertson et al. 1993; Gross et al. 1995 Editor: Erwin Dreyer F. Covelo :J. M. Ávila :A. Gallardo Department of Physical, Chemical and NaturalORIGINAL PAPER Temporal changes in the spatial pattern of leaf traits in a Quercus robur population

Paris-Sud XI, Université de

132

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

E-print Network

Temporal Patterns of Fruit Fly (Drosophila) Evolution Revealed by Mutation Clocks Koichiro Tamura events leading to the origin of this fruit fly remain elusive because of the paucity of extensive fossil-like accumulation of nucleotide and amino-acid substitutions. Here we present a novel methodology in which genomic

Kumar, Sudhir

133

Spatial pattern and temporal dynamics of northern bobwhite abundance and agricultural landuse, and potential casual factors  

E-print Network

recognizable periods in the spatial and temporal dynamics of NBW abundance between 1920 and 1990. Severe weather conditions and habitat loss due to land use change appeared to be the most important factors influencing the long-term trends and spatial patterns...

Okay, Atiye Zeynep

2006-04-12

134

TOOLS FOR PRESENTING SPATIAL AND TEMPORAL PATTERNS OF ENVIRONMENTAL MONITORING DATA  

EPA Science Inventory

The EPA Health Effects Research Laboratory has developed this data presentation tool for use with a variety of types of data which may contain spatial and temporal patterns of interest. he technology links mainframe computing power to the new generation of "desktop publishing" ha...

135

Variation in monsoon precipitation drives spatial and temporal patterns of Larrea tridentata growth in the  

E-print Network

Variation in monsoon precipitation drives spatial and temporal patterns of Larrea tridentata growth of monsoon rainfall and local rates of water infiltration. The relationship between growth and precipitation that influence infiltration and water availability following monsoon storms. 5. Overall, the strong, nonlinear

136

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

E-print Network

deviation (r) of community biomass production (Lehman & Tilman 2000). Theory predicts that biodiversity canLETTER Biodiversity, productivity and the temporal stability of productivity: patterns and processes Forest I. Isbell,1 * H. Wayne Polley2 and Brian J. Wilsey1 1 Department of Ecology, Evolution

Wilsey, Brian J.

137

Spatio-temporal patterns of fish assemblages in a large regulated alluvial  

E-print Network

or to the nearest large woody debris. However, PLS regression revealed no significant differences in habitat of woody debris and lateral/longitudinal location. Eighteen fish species were sampled by electrofishingSpatio-temporal patterns of fish assemblages in a large regulated alluvial river. Freshwater

Paris-Sud XI, Université de

138

Fourier-transform method of data compression and temporal fringe pattern analysis  

SciTech Connect

Temporal fringe pattern analysis is invaluable in studies of transient phenomena but necessitates large data storage for two essential sets of data, i.e., fringe pattern intensity and deformation phase. We describe a compression scheme based on the Fourier-transform method for temporal fringe data storage that permits retrieval of both the intensity and the deformation phase. When the scheme was used with simulated temporal wavefront interferometry intensity fringe patterns, a high compression ratio of 10.77 was achieved, with a significant useful data ratio of 0.859. The average root-mean-square error in phase value restored was a low 0.0015 rad. With simulated temporal speckle interferometry intensity fringe patterns, the important paremeters varied with the modulation cutoff value applied. For a zero modulation cutoff value, the ratio of data points and the compression ratio values obtained were roughly the same as in wavelength interferometry, albeit the average root-mean-square error in the phase value restored was far higher. By increasing the modulation cutoff value we attained significant reduction and increase in the ratio of data points and the compression ratio, respectively, whereas the average root-mean-square error in the restored phase values was reduced only slightly.

Tuck Wah Ng; Kar Tien Ang

2005-11-20

139

Infestation of leek by Thrips tabaci as related to spatial and temporal patterns of undersowing  

Microsoft Academic Search

Full field undersowing of leeks with clovers suppresses populations of adult and larval Thrips tabaci. To explore the conditions for application of this approach of IPM in commercial practice, variations in the spatial and temporal pattern of clover undersowing were studied. Effects on thrips populations, crop growth and the development of thrips feeding symptoms were recorded. Assessment of the yield

Jan Theunissen; Gijs Schelling

1998-01-01

140

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

Microsoft Academic Search

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

Neal M. Williams; James D. Thomson

1998-01-01

141

Horizontal spatial and temporal distribution patterns of nearshore larval fish assemblages at a temperate rocky shore  

Microsoft Academic Search

There have been no previous studies of the composition of nearshore larval fish assemblages along the coast of Portugal. We aimed to describe the composition and horizontal distribution patterns of larval fish assemblages and their temporal dynamics near a rocky reef at depths shallower than 13m (inshore) and at two miles (3.70km) from shore (offshore), as well as along transects

Rita Borges; Radhouan Ben-Hamadou; M. Alexandra Chícharo; Pedro Ré; Emanuel J. Gonçalves

2007-01-01

142

Variability of spatio-temporal patterns in non-homogeneous rings of spiking neurons.  

PubMed

We show that a ring of unidirectionally delay-coupled spiking neurons may possess a multitude of stable spiking patterns and provide a constructive algorithm for generating a desired spiking pattern. More specifically, for a given time-periodic pattern, in which each neuron fires once within the pattern period at a predefined time moment, we provide the coupling delays and/or coupling strengths leading to this particular pattern. The considered homogeneous networks demonstrate a great multistability of various travelling time- and space-periodic waves which can propagate either along the direction of coupling or in opposite direction. Such a multistability significantly enhances the variability of possible spatio-temporal patterns and potentially increases the coding capability of oscillatory neuronal loops. We illustrate our results using FitzHugh-Nagumo neurons interacting via excitatory chemical synapses as well as limit-cycle oscillators. PMID:22225385

Yanchuk, Serhiy; Perlikowski, Przemyslaw; Popovych, Oleksandr V; Tass, Peter A

2011-12-01

143

Variability of spatio-temporal patterns in non-homogeneous rings of spiking neurons  

NASA Astrophysics Data System (ADS)

We show that a ring of unidirectionally delay-coupled spiking neurons may possess a multitude of stable spiking patterns and provide a constructive algorithm for generating a desired spiking pattern. More specifically, for a given time-periodic pattern, in which each neuron fires once within the pattern period at a predefined time moment, we provide the coupling delays and/or coupling strengths leading to this particular pattern. The considered homogeneous networks demonstrate a great multistability of various travelling time- and space-periodic waves which can propagate either along the direction of coupling or in opposite direction. Such a multistability significantly enhances the variability of possible spatio-temporal patterns and potentially increases the coding capability of oscillatory neuronal loops. We illustrate our results using FitzHugh-Nagumo neurons interacting via excitatory chemical synapses as well as limit-cycle oscillators.

Yanchuk, Serhiy; Perlikowski, Przemyslaw; Popovych, Oleksandr V.; Tass, Peter A.

2011-12-01

144

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

NASA Astrophysics Data System (ADS)

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.

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

2011-05-01

145

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

NASA Technical Reports Server (NTRS)

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.

Hinton, Yolanda L.

1999-01-01

146

Production and Perception of Temporal Patterns in Native and Non-Native Speech  

PubMed Central

Two experiments examined production and perception of English temporal patterns by native and non-native participants. Experiment 1 indicated that native and non-native (L1 = Chinese) talkers differed significantly in their production of one English duration pattern (i.e., vowel lengthening before voiced versus voiceless consonants) but not another (i.e., tense versus lax vowels). Experiment 2 tested native and non-native listener identification of words that differed in voicing of the final consonant by the native and non-native talkers whose productions were substantially different in experiment 1. Results indicated that differences in native and non-native intelligibility may be partially explained by temporal pattern differences in vowel duration although other cues such as presence of stop releases and burst duration may also contribute. Additionally, speech intelligibility depends on shared phonetic knowledge between talkers and listeners rather than only on accuracy relative to idealized production norms. PMID:18679042

Bent, Tessa; Bradlow, Ann R.; Smith, Bruce L.

2012-01-01

147

Temporal and geographic patterns in population trends of brown-headed cowbirds  

USGS Publications Warehouse

The temporal and geographic patterns in the population trends of Brown-headed Cowbirds are summarized from the North American Breeding Bird Survey. During 1966-1992, the survey-wide population declined significantly, a result of declining populations in the Eastern BBS Region, southern Great Plains, and the Pacific coast states. Increasing populations were most evident in the northern Great Plains. Cowbird populations were generally stable or increasing during 1966-1976, but their trends became more negative after 1976. The trends in cowbird populations were generally directly correlated with the trends of both host and nonhost species, suggesting that large-scale factors such as changing weather patterns, land use practices, or habitat availability were responsible for the observed temporal and geographic patterns in the trends of cowbirds and their hosts.

Peterjohn, B.G.; Sauer, J.R.; Schwarz, S.

2000-01-01

148

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

PubMed Central

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

Francis, Malcolm P.

2013-01-01

149

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

PubMed Central

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

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

2013-01-01

150

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

PubMed

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

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

151

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

PubMed

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

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

152

Temporal consistency of spatial pattern in growth of the mussel, Mytilus edulis: Implications for predictive modelling  

NASA Astrophysics Data System (ADS)

Human pressures on coastal seas are increasing and methods for sustainable management, including spatial planning and mitigative actions, are therefore needed. In coastal areas worldwide, the development of mussel farming as an economically and ecologically sustainable industry requires geographic information on the growth and potential production capacity. In practice this means that coherent maps of temporally stable spatial patterns of growth need to be available in the planning process and that maps need to be based on mechanistic or empirical models. Therefore, as a first step towards development of models of growth, we assessed empirically the fundamental requirement that there are temporally consistent spatial patterns of growth in the blue mussel, Mytilus edulis. Using a pilot study we designed and dimensioned a transplant experiment, where the spatial consistency in the growth of mussels was evaluated at two resolutions. We found strong temporal and scale-dependent spatial variability in growth but patterns suggested that spatial patterns were uncoupled between growth of shell and that of soft tissue. Spatial patterns of shell growth were complex and largely inconsistent among years. Importantly, however, the growth of soft tissue was qualitatively consistent among years at the scale of km. The results suggest that processes affecting the whole coastal area cause substantial differences in growth of soft tissue among years but that factors varying at the scale of km create strong and persistent spatial patterns of growth, with a potential doubling of productivity by identifying the most suitable locations. We conclude that the observed spatial consistency provides a basis for further development of predictive modelling and mapping of soft tissue growth in these coastal areas. Potential causes of observed patterns, consequences for mussel-farming as a tool for mitigating eutrophication, aspects of precision of modelling and sampling of mussel growth as well as ecological functions in general are discussed.

Bergström, Per; Lindegarth, Susanne; Lindegarth, Mats

2013-10-01

153

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

NASA Astrophysics Data System (ADS)

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.

Sebestyen, Stephen D.; Schneider, Rebecca L.

2001-07-01

154

Multi-scale patterning of microparticles using a combination of surface acoustic waves and ultrasonic bulk waves  

NASA Astrophysics Data System (ADS)

Standing surface acoustic waves (SAWs) and standing bulk waves (BWs) are combined to pattern two populations of particles with differing sizes. Patterns with large differences in wavelength in each direction and simultaneous generation of different patterns for each population are demonstrated. Particles are trapped at nodal positions of orthogonal standing wave fields in patterns determined by device voltage amplitudes and frequencies. 10-?m beads are trapped at points at the intersection of the pressure nodes of the SAW and BW fields, and 1-?m beads are trapped in lines at the pressure nodes of the SAW field, producing a multi-scale pattern.

Zhang, Jie; Meng, Long; Cai, Feiyan; Zheng, Hairong; Courtney, Charles R. P.

2014-06-01

155

Can acoustic emissions patterns signal imminence of avalanche events in a growing sand pile?  

NASA Astrophysics Data System (ADS)

Gravity driven mass release is often triggered abruptly with limited precursory cues to indicate imminent failure and thus limiting early warning. Evidence suggests that with increased mechanical loading of a slope, numerous local damage events marking friction between rearranged particles or breakage of roots release strain energy as elastic waves measurable as acoustic emissions. We examined the potential predictability of mass release events from preceding acoustic emission (AE) signatures in a well-known and simple model system of a growing sand pile. We installed four AE-sensors within the core of a 30 cm (diameter) sand pile fed by a constant input of grains and mounted on a balance. Subsequent to the convergence of the slope to dynamic angle of repose, sand avalanche across the bottom boundary were monitored by abrupt mass change and by the amplitudes and number of AE events (recorded at high frequency and averaged to 0.2 s). We detected a systematic change of AE-patterns characterized by systematically decreasing AE standard deviation prior to each mass release. Although the lead time following minimum AE standard deviation was relatively short (10s of seconds), the AE signature already started to change minutes before the mass release. Accordingly the information embedded in AE signal dynamics could potentially offer larger lead times for systems of practical interest.

Vögtli, Melanie; Lehmann, Peter; Breitenstein, Daniel; Or, Dani

2014-05-01

156

Spatio-temporal patterns and dynamics of net primary productivity for Kazakhstan  

NASA Astrophysics Data System (ADS)

Monitoring of net primary productivity (NPP) is especially important for the fragile ecosystems in arid and semi-arid regions. Great interest exists in observing large-scale vegetation dynamics and understanding spatial and temporal patterns of NPP in these areas. In this study we present results of NPP obtained with the model BETHY/DLR for Kazakhstan for 2003-2011 and its spatial and temporal dynamics. The spatial distribution of vegetation productivity shows a gradient from North to South and clear differences between individual vegetation classes. The monthly NPP values show the highest productivity in June. Differences between rain-fed and irrigated areas indicate the dependency on water availability. Annual NPP variability was high for agricultural areas, but showed low values for natural vegetation. The analysis of different patterns in vegetation productivity provides valuable information for the identification of regions that are vulnerable to a possible climate change. This information may thus substantially support a sustainable land management.

Eisfelder, C.; Klein, I.; Huth, J.; Niklaus, M.; Kuenzer, C.

2014-03-01

157

The selective control of glycolysis, gluconeogenesis and glycogenesis by temporal insulin patterns.  

PubMed

Insulin governs systemic glucose metabolism, including glycolysis, gluconeogenesis and glycogenesis, through temporal change and absolute concentration. However, how insulin-signalling pathway selectively regulates glycolysis, gluconeogenesis and glycogenesis remains to be elucidated. To address this issue, we experimentally measured metabolites in glucose metabolism in response to insulin. Step stimulation of insulin induced transient response of glycolysis and glycogenesis, and sustained response of gluconeogenesis and extracellular glucose concentration (GLC(ex)). Based on the experimental results, we constructed a simple computational model that characterises response of insulin-signalling-dependent glucose metabolism. The model revealed that the network motifs of glycolysis and glycogenesis pathways constitute a feedforward (FF) with substrate depletion and incoherent feedforward loop (iFFL), respectively, enabling glycolysis and glycogenesis responsive to temporal changes of insulin rather than its absolute concentration. In contrast, the network motifs of gluconeogenesis pathway constituted a FF inhibition, enabling gluconeogenesis responsive to absolute concentration of insulin regardless of its temporal patterns. GLC(ex) was regulated by gluconeogenesis and glycolysis. These results demonstrate the selective control mechanism of glucose metabolism by temporal patterns of insulin. PMID:23670537

Noguchi, Rei; Kubota, Hiroyuki; Yugi, Katsuyuki; Toyoshima, Yu; Komori, Yasunori; Soga, Tomoyoshi; Kuroda, Shinya

2013-01-01

158

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

159

Spatial and temporal patterns in macrofaunal diversity components relative to sea floor landscape structure.  

PubMed

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

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

2013-01-01

160

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

Microsoft Academic Search

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

Timothy C. Roth; Steven L. Lima

2007-01-01

161

A Sequence Identification Measurement Model to Investigate the Implicit Learning of Metrical Temporal Patterns  

PubMed Central

Implicit learning (IL) occurs unconsciously and without intention. Perceptual fluency is the ease of processing elicited by previous exposure to a stimulus. It has been assumed that perceptual fluency is associated with IL. However, the role of perceptual fluency following IL has not been investigated in temporal pattern learning. Two experiments by Schultz, Stevens, Keller, and Tillmann demonstrated the IL of auditory temporal patterns using a serial reaction-time task and a generation task based on the process dissociation procedure. The generation task demonstrated that learning was implicit in both experiments via motor fluency, that is, the inability to suppress learned information. With the aim to disentangle conscious and unconscious processes, we analyze unreported recognition data associated with the Schultz et al. experiments using the sequence identification measurement model. The model assumes that perceptual fluency reflects unconscious processes and IL. For Experiment 1, the model indicated that conscious and unconscious processes contributed to recognition of temporal patterns, but that unconscious processes had a greater influence on recognition than conscious processes. In the model implementation of Experiment 2, there was equal contribution of conscious and unconscious processes in the recognition of temporal patterns. As Schultz et al. demonstrated IL in both experiments using a generation task, and the conditions reported here in Experiments 1 and 2 were identical, two explanations are offered for the discrepancy in model and behavioral results based on the two tasks: 1) perceptual fluency may not be necessary to infer IL, or 2) conscious control over implicitly learned information may vary as a function of perceptual fluency and motor fluency. PMID:24086461

Schultz, Benjamin G.; Stevens, Catherine J.; Keller, Peter E.; Tillmann, Barbara

2013-01-01

162

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

PubMed Central

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

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

2013-01-01

163

Spatial and Temporal Patterns of Terrorist Attacks by ETA 1970 to 2007  

Microsoft Academic Search

Rational choice perspectives maintain that seemingly irrational behavior on the part of terrorist organizations may nevertheless\\u000a reflect strategic planning. In this paper we examine spatial and temporal patterns of terrorist attacks by the Spanish group\\u000a ETA between 1970 and 2007. Our analysis is guided by a public announcement by ETA in 1978 that the group would shift from\\u000a emphasizing attacks

Gary LaFreeLaura; Laura Dugan; Min Xie; Piyusha Singh

164

Spatio-Temporal Segregation-Pattern Drift in Particle-Laden Rimming Flow  

NASA Astrophysics Data System (ADS)

In Ref. [1] we described a new banding pattern developing from particle segregation in particle-laden flow inside a partially fluid-filled, horizontal, rotating cylinder. Hitherto we believed that the pattern was quasi stationary once developed. However, long-term observations have revealed that this is not the case. The system can display an extremely rich spatio- temporal behaviour that emerges as the patterns drift extremely slowly along the axis of rotation. Due to these low average pattern-drift velocities the complex system dynamics often only reveal themselves when conducting experiments extending over several weeks. Here we discuss some of the observed typical aspects of the long-term behaviour of the system for the first time. [1] Boote, O.A.M. & Thomas, P.J. 1999 Effects of granular additives on transition boundaries between flow states of rimming flow, Phys. Fluids vol. 11, 2020-2029.

Guyez, Estelle; Thomas, Peter J.

2007-11-01

165

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

PubMed

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

Matell, Matthew S

2014-01-01

166

Temporal investigation of acoustic wave pressure spectrum of high repetition rate TEA-CO 2 lasers by using a three-dimensional mathematical model  

NASA Astrophysics Data System (ADS)

The production of acoustic wave is one of the most important factors on the action of High Repetition Rate TEA-CO 2 lasers. In this paper a three-dimensional mathematical modeling has been considered for investigation of temporal and spatial variations of acoustic waves in the laser cavity and its effect on the output of HRR lasers. By calculation of equations obtained from this model and plotting the pressure spectrum in different states, the effect of electrodes dimensions, cavity dimensions, gas flow velocity and repetition rate of laser in different times have been acquired. At last, optimum conditions for performance of laser action and having a good output have been arrived.

Rahimi, M.; Baghshahi, H. R.; Marashi, S. M. B.

2011-04-01

167

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

E-print Network

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

Vorperian, Houri K.

168

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

PubMed Central

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

Arenas, Ernest; Rodriguez, Francisco Javier

2012-01-01

169

Temporal Pattern of Cocaine Intake Determines Tolerance vs Sensitization of Cocaine Effects at the Dopamine Transporter  

PubMed Central

The dopamine transporter (DAT) is responsible for terminating dopamine (DA) signaling and is the primary site of cocaine's reinforcing actions. Cocaine self-administration has been shown previously to result in changes in cocaine potency at the DAT. To determine whether the DAT changes associated with self-administration are due to differences in intake levels or temporal patterns of cocaine-induced DAT inhibition, we manipulated cocaine access to produce either continuous or intermittent elevations in cocaine brain levels. Long-access (LgA, 6?h) and short-access (ShA, 2?h) continuous self-administration produced similar temporal profiles of cocaine intake that were sustained throughout the session; however, LgA had greater intake. ShA and intermittent-access (IntA, 6?h) produced the same intake, but different temporal profiles, with ‘spiking' brain levels in IntA compared with constant levels in ShA. IntA consisted of 5-min access periods alternating with 25-min timeouts, which resulted in bursts of high responding followed by periods of no responding. DA release and uptake, as well as the potency of cocaine for DAT inhibition, were assessed by voltammetry in the nucleus accumbens slices following control, IntA, ShA, and LgA self-administration. Continuous-access protocols (LgA and ShA) did not change DA parameters, but the ‘spiking' protocol (IntA) increased both release and uptake of DA. In addition, high continuous intake (LgA) produced tolerance to cocaine, while ‘spiking' (IntA) produced sensitization, relative to ShA and naive controls. Thus, intake and pattern can both influence cocaine potency, and tolerance seems to be produced by high intake, while sensitization is produced by intermittent temporal patterns of intake. PMID:23719505

Calipari, Erin S; Ferris, Mark J; Zimmer, Benjamin A; Roberts, David CS; Jones, Sara R

2013-01-01

170

Spatio-temporal patterns of antennal movements in the searching cockroach.  

PubMed

To characterize the spatio-temporal patterns of antennal behavior in insects, the voluntary movement of both right and left antennae was examined in the cockroach Periplaneta americana. The position of the tip of the antenna (flagellum) is controlled by two mobile joints at its base (the scape and the pedicel) and by the neck. Horizontal and vertical components of movement at the antennal basal joints exhibited rhythmic activities during locomotory (walking) and non-locomotory (pausing) states in the searching animal. In both states, the horizontal component was slower than vertical one. Joint-manipulation experiments suggested that the faster vertical component is due mainly to movements of the scape-pedicel joint, while the slower horizontal component may originate from the head-scape joint. Large horizontal deflections of the antenna corresponded consistently with the yaw component of head movement. The trajectories of the antennae showed little patterned regularity in most animals. In a few cases, however, loop-like patterns appeared. The area scanned by an antenna was narrower in the walking state than in the pausing state, mainly because of a decrease in the horizontal angular range. Cross-correlation analyses revealed that the coupling between right and left horizontal antennal motor systems and that for the vertical systems were both significantly stronger in the walking state than during pausing. These results indicate that the spatio-temporal pattern of antennal movements changes dynamically depending on the animal's behavioral state. PMID:15371477

Okada, Jiro; Toh, Yoshihiro

2004-10-01

171

New model of human luminance pattern vision mechanisms: analysis of the effects of pattern orientation, spatial phase, and temporal frequency  

NASA Astrophysics Data System (ADS)

Models of human pattern vision mechanisms are examined in light of new results in psychophysics and single-cell recording. Four experiments on simultaneous masking of Gabor patterns by sinewave gratings are described. In these experiments target contrast thresholds are measured as functions of masker contrast, orientation, spatial phase, and temporal frequency. The results are used to test the theory of simultaneous masking proposed by Legge and Foley that is based on mechanisms that sum excitation linearly over a receptive field and produce a response that is an s-shaped transform of this sum. The theory is shown to be inadequate. Recent single-cell-recording results from simple cells in the cat show that these cells receive a broadband divisive input as well as an input that is summed linearly over their receptive fields. A new theory of simultaneous masking based on mechanisms with similar properties is shown to describe the psychophysical results well. Target threshold vs masker contrast (TvC) functions for a set of target-masker pairs are used to estimate the parameters of the theory including the excitatory and inhibitory sensitivities of the mechanisms along the various pattern dimensions. The human luminance pattern vision mechanisms, unlike most of the cells, do not saturate at high contrast.

Foley, John M.; Boynton, Geoffrey M.

1994-03-01

172

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

NASA Astrophysics Data System (ADS)

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.

Hassler, Sibylle; Weiler, Markus; Blume, Theresa

2014-05-01

173

Analysis of spatial and temporal water pollution patterns in Lake Dianchi using multivariate statistical methods.  

PubMed

Various multivariate statistical methods including cluster analysis (CA), discriminant analysis (DA), factor analysis (FA), and principal component analysis (PCA) were used to explain the spatial and temporal patterns of surface water pollution in Lake Dianchi. The dataset, obtained during the period 2003-2007 from the Kunming Environmental Monitoring Center, consisted of 12 variables surveyed monthly at eight sites. The CA grouped the 12 months into two groups, August-September and the remainder, and divided the lake into two regions based on their different physicochemical properties and pollution levels. The DA showed the best results for data reduction and pattern recognition in both temporal and spatial analysis. It calculated four parameters (TEMP, pH, CODMn, and Chl-a) to 85.4% correct assignment in the temporal analysis and three parameters (BOD, NH?+-N, and TN) to almost 71.7% correct assignment in spatial analysis of the two clusters. The FA/PCA applied to datasets of two special clusters of the lake calculated four factors for each region, capturing 72.5% and 62.5% of the total variance, respectively. Strong loadings included DO, BOD, TN, CODCr, CODMn, NH?+-N, TP, and EC. In addition, box-whisker plots and GIS further facilitated and supported the multivariate analysis results. PMID:19936953

Yang, Yong-Hui; Zhou, Feng; Guo, Huai-Cheng; Sheng, Hu; Liu, Hui; Dao, Xu; He, Cheng-Jie

2010-11-01

174

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

175

Temporal organization of an anuran acoustic community in a Taiwanese subtropical forest  

USGS Publications Warehouse

We recorded anuran vocalizations in each of four habitats at Lien Hua Chih Field Station, Taiwan, between July 2000 and July 2001. For each 27 biweekly sample, eight recorders taped calls for 1 min out of every 11 between the hours of 17:00 and 07:00. We obtained 11 481 recordings with calls, and identified 21 503 frogs or groups of frogs. These included 20 species, with an average of 10.4??3.5 species calling each night. Some species called year round, others called in the spring and summer, and a third group called only in the fall and winter. The number of species calling and the maximum calling intensity were correlated with both rainfall and air temperature. The nightly pattern of calling varied among species. Most species called continuously throughout the night, whereas some had a peak right after dusk. A few species had different nightly calling patterns in different habitats. Both Rana limnocharis and Rana kuhlii changed their calling pattern in the presence of large choruses of other anuran species. ?? 2006 The Authors.

Hsu, M. -Y.; Kam, Y. -C.; Fellers, G. M.

2006-01-01

176

Temporal and spatial patterns in vegetation and atmospheric properties from AVIRIS  

SciTech Connect

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.

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

177

Are obsidian subsources meaningful units of analysis?: temporal and spatial patterning of subsources in the Coso Volcanic Field,  

E-print Network

Are obsidian subsources meaningful units of analysis?: temporal and spatial patterning reserved. Keywords: Obsidian fingerprinting; Intra-source variability; Coso Volcanic Field; California. Obsidian sourcing, or finger- printing, has greatly advanced our understanding and knowledge of obsidian

178

Analysing spatio-temporal pattern of changing farmland in China's arid zone  

NASA Astrophysics Data System (ADS)

Multi-temporal imagery has been used for landuse and land cover change detection since the very early stage of remote sensing technology. As large amount of remotely sensed data have been collected, historical land cover changes and change patterns can be reconstructed by a time series recorded by images. This paper reports a study on the methodology for quantifying spatial pattern of land cover changes in an arid zone during a 13-year period and the attempts to identify the key factors for these changes. The approach is based on the post-classification method. Multi-temporal images were independently classified to establish change trajectories for the farmland land cover type. A set of class-level metrics is then calculated on the trajectory classes, including Percentage of Landscape (PLAND), Normalized Landscape Shape Index (NLSI), Interspersion and Juxtaposition Index (IJI) and Area Weighted Fractal Dimension Index (FRAC_AM). These metrics and their relationship were shown as good indicators on the environmental impact in the fragile ecosystem due to the rapid expansion of farmland accompanied with the limited water resources. The results show that spatial pattern metrics of land cover change trajectories provide an effective measurement on landscape changes, which can further be interpreted for agriculture planning and management.

Zhou, Qiming; Sun, Bo

2008-10-01

179

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

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

180

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

PubMed Central

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

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

2014-01-01

181

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

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

182

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

PubMed Central

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

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

2013-01-01

183

Temporally shaped femtosecond laser pulses as direct patterning method for dielectric materials in nanophotonic applications  

NASA Astrophysics Data System (ADS)

We present a direct patterning method of dielectric materials via temporally shaped femtosecond laser pulses. A thinfilm waveguide with a 2D periodic pattern of photonic crystals with circular base elements is investigated. We use dielectrics since they are transparent especially in the visible spectral range, but also in UV and near infrared range. Thus, they are very suitable as optical filters in the very same spectral region. Since structuring of non-conductive dielectric materials suffers from charging, the implementation of laser processing as patterning method instead of conventional processing techniques like electron beam lithography or focused ion beams is a very attractive alternative. Despite a low refractive index contrast, we show by numerical results that normal incident of light to the plane of periodicity couples to a waveguide mode and can excite Fano resonances. That makes the device extremely interesting as narrow-band optical filter. Applications of optical filters in the visible and UV range require fabrication of photonic crystal structures in the sub-100 nm range. Temporally shaped femtosecond laser pulses are applied as a novel method for very high precision laser processing of wide band gap materials to create photonic crystal structures in dielectrics. Shaping temporally asymmetric pulse trains enable the production of structures well below the diffraction limit.1 We combine this process with deposition of a high refractive index layer to achieve the targeted resonant waveguide structure. Additionally, we focus on the rim formation arising by laser processing since this is an important issue for fabrication of photonic crystal arrays with small lattice constants.

Meinl, Tamara; Götte, Nadine; Khan, Yousuf; Kusserow, Thomas; Sarpe, Cristian; Köhler, Jens; Wollenhaupt, Matthias; Senftleben, Arne; Baumert, Thomas; Hillmer, Harmut

2014-05-01

184

The impact of spatial and temporal patterns on multi-cellular behavior  

NASA Astrophysics Data System (ADS)

What makes a fruit fly a fruit fly? Essentially this question stems from one of the most fascinating problems in biology: how a single cell (fertilized egg) can give rise to a fully grown animal. To be able to answer this question, the importance to how spatial and temporal patterns of gene and protein expression influence the development of an organism must be understood. After all, fruit fly larvae are segmented, while fertilized eggs are not. Pattern formation is fundamental to establishing this organization of the developing embryo with the ultimate goal being the precise arrangements of specialized cells and tissues within each organ in an adult organism. The research presented here showcases the examples of studies that assess the impact spatial and temporal protein patterns have on the behavior of a collection of cells. By introducing new experimental, non-traditional techniques we developed model systems that allowed us to examine the dependence of the strength of adhesion of cells on the protein organization on sub-cellular, micron length scales, and to investigate how epithelial cell sheets coordinate their migration incorporating individual cell locomotion, molecular signal propagation and different boundary conditions. The first part of this dissertation presents a photolithography-based silanization patterning technique that allowed us to homogeneously pattern large areas with high precision. This method is then applied to organizing cell adhesion-promoting proteins on surfaces for the purposes of studying and manipulating cell behavior. We show how the strength of adhesion is dependent on high local density of an adhesive extracellular matrix protein fibronectin. The varied appeal of this technique is exhibited by showing its applicability to pattern stretched DNA, too. The second part of this dissertation focuses on the impact of spatial and temporal propagation of a molecular signal (ERK 1/2 MAPK) in migrating epithelial sheets during wound healing. By tracking the motion of individual cells within the sheet under the three constructed conditions, we show how the dynamics of the individual cells' motion is responsible for the coordinated migration of the sheet in accordance with the activation of ERK 1/2 MAPK.

Nikolic, Djordje L.

185

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

PubMed Central

Aquatic species of Utricularia are carnivorous plants living in environments poor in nutrients. Their trapping mechanism has fascinated generations of scientists and is still debated today. It was reported recently that Utricularia traps can fire spontaneously. We show here that these spontaneous firings follow an unexpected diversity of temporal patterns, from “metronomic” traps which fire at fixed time intervals to “random” patterns, displaying more scattered firing times. Some “bursting” traps even combine both aspects, with groups of fast regular firings separated by a variable amount of time. We propose a physical model to understand these very particular behaviors, showing that a trap of Utricularia accomplishes mechanical oscillations, based on continuous pumping and sudden opening of the trap door (buckling). We isolate the key parameters governing these oscillations and discuss the effect of their fluctuations. PMID:21647417

Vincent, Olivier; Roditchev, Ivan; Marmottant, Philippe

2011-01-01

186

Spontaneous firings of carnivorous aquatic Utricularia traps: temporal patterns and mechanical oscillations.  

PubMed

Aquatic species of Utricularia are carnivorous plants living in environments poor in nutrients. Their trapping mechanism has fascinated generations of scientists and is still debated today. It was reported recently that Utricularia traps can fire spontaneously. We show here that these spontaneous firings follow an unexpected diversity of temporal patterns, from "metronomic" traps which fire at fixed time intervals to "random" patterns, displaying more scattered firing times. Some "bursting" traps even combine both aspects, with groups of fast regular firings separated by a variable amount of time. We propose a physical model to understand these very particular behaviors, showing that a trap of Utricularia accomplishes mechanical oscillations, based on continuous pumping and sudden opening of the trap door (buckling). We isolate the key parameters governing these oscillations and discuss the effect of their fluctuations. PMID:21647417

Vincent, Olivier; Roditchev, Ivan; Marmottant, Philippe

2011-01-01

187

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

188

Spatio-temporal pattern of vestibular information processing after brief caloric stimulation.  

PubMed

Processing of vestibular information at the cortical and subcortical level is essential for head and body orientation in space and self-motion perception, but little is known about the neural dynamics of the brain regions of the vestibular system involved in this task. Neuroimaging studies using both galvanic and caloric stimulation have shown that several distinct cortical and subcortical structures can be activated during vestibular information processing. The insular cortex has been often targeted and presented as the central hub of the vestibular cortical system. Since very short pulses of cold water ear irrigation can generate a strong and prolonged vestibular response and a nystagmus, we explored the effects of this type of caloric stimulation for assessing the blood-oxygen-level-dependent (BOLD) dynamics of neural vestibular processing in a whole-brain event-related functional magnetic resonance imaging (fMRI) experiment. We evaluated the spatial layout and the temporal dynamics of the activated cortical and subcortical regions in time-locking with the instant of injection and were able to extract a robust pattern of neural activity involving the contra-lateral insular cortex, the thalamus, the brainstem and the cerebellum. No significant correlation with the temporal envelope of the nystagmus was found. The temporal analysis of the activation profiles highlighted a significantly longer duration of the evoked BOLD activity in the brainstem compared to the insular cortex suggesting a functional de-coupling between cortical and subcortical activity during the vestibular response. PMID:18342473

Marcelli, Vincenzo; Esposito, Fabrizio; Aragri, Adriana; Furia, Teresa; Riccardi, Pasquale; Tosetti, Michela; Biagi, Laura; Marciano, Elio; Di Salle, Francesco

2009-05-01

189

Population dynamics of wetland fishes: Spatio-temporal patterns synchronized by hydrological disturbance?  

USGS Publications Warehouse

1. Drought is a natural disturbance that can cause widespread mortality of aquatic organisms in wetlands. We hypothesized that seasonal drying of marsh surfaces (i.e. hydrological disturbance) shapes spatio-temporal patterns of fish populations. 2. We tested whether population dynamics of fishes were synchronized by hydrological disturbance (Moran effect) or distance separating study sites (dispersal). Spatio-temporal patterns were examined in local populations of five abundant species at 17 sites (sampled five times per year from 1996 to 2001) in a large oligotrophic wetland. 3. Fish densities differed significantly across spatio-temporal scales for all species. For all species except eastern mosquitofish (Gambusia holbrooki), a significant portion of spatio-temporal variation in density was attributed to drying events (used as a covariate). 4. We observed three patterns of response to hydrological disturbance. Densities of bluefin killifish (Lucania goodei), least killifish (Heterandria formosa), and golden top-minnow (Fundulus chrysotus) were usually lowest after a dry down and recovered slowly. Eastern mosquitofish showed no distinct response to marsh drying (i.e. they recovered quickly). Flagfish (Jordanella floridae) density was often highest after a dry down and then declined. Population growth after a dry down was often asymptotic for bluefin killifish and golden topminnow, with greatest asymptotic density and longest time to recovery at sites that dried infrequently. 5. Fish population dynamics were synchronized by hydrological disturbance (independent of distance) and distance separating study sites (independent of hydrological disturbance). Our ability to separate the relative importance of the Moran effect from dispersal was strengthened by a weak association between hydrological synchrony and distance among study sites. Dispersal was the primary mechanism for synchronous population dynamics of flagfish, whereas hydrological disturbance was the primary mechanism for synchronous population dynamics of the other species examined. 6. Species varied in the relative role of the Moran effect and dispersal in homogenizing their population dynamics, probably as a function of life history and ability to exploit dry-season refugia. ?? 2005 British Ecological Society.

Ruetz, C. R., III; Trexler, J.C.; Jordan, F.; Loftus, W.F.; Perry, S.A.

2005-01-01

190

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

NASA Astrophysics Data System (ADS)

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 properties. The role of lichen crusts in ? conservation has been demonstrated even when the properties of the soil beneath do not favour water storage. Differences in soil moisture regimes have been found below inter-shrub (open) areas and below shrubs. The influence of most terrain attributes (slope gradient and aspect, specific catchment area, slope curvature, wetness index, slope length factor and distance to channels on ? is masked by the influence of soil cover properties. The simultaneous monitoring of rainfall, soil moisture and runoff at short intervals shows the different responses of soil surfaces to rainfall and the influence of rainfall partitioning on soil moisture patterns. This work contributes to an understanding of several aspects of spatial and temporal variability of ? in semiarid areas and the factors controlling it, and provides key information for their management.

Cantón, Y.; Solé-Benet, A.; Domingo, F.

2004-01-01

191

Local Temporal Correlation Common Spatial Patterns for Single Trial EEG Classification during Motor Imagery  

PubMed Central

Common spatial pattern (CSP) is one of the most popular and effective feature extraction methods for motor imagery-based brain-computer interface (BCI), but the inherent drawback of CSP is that the estimation of the covariance matrices is sensitive to noise. In this work, local temporal correlation (LTC) information was introduced to further improve the covariance matrices estimation (LTCCSP). Compared to the Euclidean distance used in a previous CSP variant named local temporal CSP (LTCSP), the correlation may be a more reasonable metric to measure the similarity of activated spatial patterns existing in motor imagery period. Numerical comparisons among CSP, LTCSP, and LTCCSP were quantitatively conducted on the simulated datasets by adding outliers to Dataset IVa of BCI Competition III and Dataset IIa of BCI Competition IV, respectively. Results showed that LTCCSP achieves the highest average classification accuracies in all the outliers occurrence frequencies. The application of the three methods to the EEG dataset recorded in our laboratory also demonstrated that LTCCSP achieves the highest average accuracy. The above results consistently indicate that LTCCSP would be a promising method for practical motor imagery BCI application. PMID:24348740

Xu, Peng; Liu, Tiejun; Zhang, Yangsong; Guo, Lanjin; Li, Peiyang; Yao, Dezhong

2013-01-01

192

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

PubMed

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

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

2011-06-01

193

Spatial and temporal patterns of seed dispersal: an important determinant of grassland invasion.  

PubMed

We measured spatial and temporal patterns of seed dispersal and seedling recruitment for 58 species in a grassland community to test whether seed dispersal could predict patterns of invasion after disturbance. For the 12 most abundant grasses, recruitment of native species was dependent on the propagule supply of both native and exotic species. Variability in seed rain on small spatial (1-10 m) and temporal (within season) scales led to qualitative differences in the outcome of disturbance colonization such that native species dominated disturbances when exotic seed supply was low but failed to establish when exotic seed supply was high. Local dispersal and spatial heterogeneity in species composition promoted coexistence of native and exotic species by creating refuges from high exotic seed supply within native dominated patches. Despite this, copious exotic seed production strongly limited recruitment of native species in exotic dominated patches. Most grasslands in California are presently dominated by exotic species, suggesting that competition at the seedling stage is a major barrier to native species restoration. PMID:17489239

DiVittorio, Christopher T; Corbin, Jeffrey D; D'Antonio, Carla M

2007-03-01

194

Temporal patterns of human and canine Giardia infection in the United States: 2003-2009.  

PubMed

Giardia protozoa have been suspected to be of zoonotic transmission, including transmission from companion animals such as pet dogs to humans. Patterns of infection have been previously described for dogs and humans, but such investigations have used different time periods and locations for these two species. Our objective was to describe and compare the overall trend and seasonality of Giardia species infection among dogs and humans in the United States from 2003 through 2009 in an ecological study using public health surveillance data and medical records of pet dogs visiting a large nationwide private veterinary hospital. Canine data were obtained from all dogs visiting Banfield hospitals in the United States with fecal test results for Giardia species, from January 2003 through December 2009. Incidence data of human cases from the same time period were obtained from the CDC. Descriptive time plots, a seasonal trend decomposition (STL) procedure, and seasonal autoregressive moving-average (SARIMA) models were used to assess the temporal characteristics of Giardia infection in the two species. Canine incidence showed a gradual decline from 2003 to 2009 with no significant/distinct regular seasonal component. By contrast, human incidence showed a stable annual rate with a significant regular seasonal cycle, peaking in August and September. Different temporal patterns in human and canine Giardia cases observed in this study suggest that the epidemiological disease processes underlying both series might be different, and Giardia transmission between humans and their companion dogs seems uncommon. PMID:24309130

Mohamed, Ahmed S; Levine, Michael; Camp, Joseph W; Lund, Elisabeth; Yoder, Jonathan S; Glickman, Larry T; Moore, George E

2014-02-01

195

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

PubMed Central

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

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

2007-01-01

196

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

PubMed Central

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

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

2012-01-01

197

The Chronotron: A Neuron That Learns to Fire Temporally Precise Spike Patterns  

PubMed Central

In many cases, neurons process information carried by the precise timings of spikes. Here we show how neurons can learn to generate specific temporally precise output spikes in response to input patterns of spikes having precise timings, thus processing and memorizing information that is entirely temporally coded, both as input and as output. We introduce two new supervised learning rules for spiking neurons with temporal coding of information (chronotrons), one that provides high memory capacity (E-learning), and one that has a higher biological plausibility (I-learning). With I-learning, the neuron learns to fire the target spike trains through synaptic changes that are proportional to the synaptic currents at the timings of real and target output spikes. We study these learning rules in computer simulations where we train integrate-and-fire neurons. Both learning rules allow neurons to fire at the desired timings, with sub-millisecond precision. We show how chronotrons can learn to classify their inputs, by firing identical, temporally precise spike trains for different inputs belonging to the same class. When the input is noisy, the classification also leads to noise reduction. We compute lower bounds for the memory capacity of chronotrons and explore the influence of various parameters on chronotrons' performance. The chronotrons can model neurons that encode information in the time of the first spike relative to the onset of salient stimuli or neurons in oscillatory networks that encode information in the phases of spikes relative to the background oscillation. Our results show that firing one spike per cycle optimizes memory capacity in neurons encoding information in the phase of firing relative to a background rhythm. PMID:22879876

Florian, R?zvan V.

2012-01-01

198

Risk based management of contaminated sediments: consideration of spatial and temporal patterns in exposure modeling.  

PubMed

This paper addresses interactions among foraging behavior, habitat preferences, site characteristics, and spatial distribution of contaminants in developing PCB exposure estimates for winter flounder at a hypothetical open water dredged material disposal site in the coastal waters of New York and New Jersey (NY-NJ). The implications of these interactions for human health risk estimates for local recreational anglers who fish for and eat flounder are described. The models implemented in this study include a spatial submodel to account for spatial and temporal characteristics of fish exposures and a probabilistic adaptation of the Gobas bioaccumulation model that accounts for temporal variation in concentrations of hydrophobic contaminants in sediment and water. We estimated the geographic distribution of a winter flounder subpopulation offshore of NY-NJ based on species biology and its vulnerability to local recreational fishing, the foraging area of individual fish, and their migration patterns. We incorporated these parameters and an estimate of differential attraction to a management site into a spatially explicit model to assess the range of exposures within the population. The output of this modeling effort, flounder PCB tissue concentrations, provided exposure point concentrations for an estimate of human health risk through ingestion of locally caught flounder. The risks obtained for the spatially nonexplicit case are as much as 1 order of magnitude higher than those obtained with explicit consideration of spatial and temporal characteristics of winter flounder foraging and seasonal migration. This practice of "defaulting" to extremely conservative estimates for exposure parameters in the face of uncertainty ill serves the decision-making process for management of contaminated sediments in general and specifically for disposal of dredged materials. Consideration of realistic spatial and temporal scales in food chain models can help support sediment management decisions by providing a quantitative expression of the confidence in risk estimates. PMID:11827058

Linkov, Igor; Burmistrov, Dmitriy; Cura, Jerome; Bridges, Todd S

2002-01-15

199

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

PubMed

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

Behar, Hilla; Brenner, Naama; Louzoun, Yoram

2014-09-01

200

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

PubMed Central

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

Bosiger, Yoland J.; McCormick, Mark I.

2014-01-01

201

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

PubMed

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

Bosiger, Yoland J; McCormick, Mark I

2014-01-01

202

Fish and Plankton Interplay Determines Both Plankton Spatio-Temporal Pattern Formation and Fish School Walks: A Theoretical Study  

Microsoft Academic Search

The fascinating variety of spatio-temporal patterns in aquatic ecosystems and the understanding of the governing mechanisms of its generation and further dynamics requires ongoing experimental and theoretical studies. After introducing a certain hybrid mathematical model, this paper makes an attempt to demonstrate that the predation of a mobile planktivorous fish school on zooplankton can initiate both plankton pattern formation and

Alexander B. Medvinsky; Dmitry A. Tikhonov; Jörg Enderlein; Horst Malchow

2000-01-01

203

Measuring the scaling properties of temporal and spatial patterns: from the human eye to the foraging albatross  

E-print Network

Measuring the scaling properties of temporal and spatial patterns: from the human eye, we will move on to a physical system ­ movements of the human eye as a person looks at patterns projected on a screen. The human eye is chosen because it highlights the challenges of interpreting real

Taylor, Richard

204

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

Microsoft Academic Search

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

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

2008-01-01

205

Response Pattern Based on the Amplitude of Ear Canal Recorded Cochlear Microphonic Waveforms across Acoustic Frequencies in Normal Hearing Subjects  

PubMed Central

Low-frequency otoacoustic emissions (OAEs) are often concealed by acoustic background noise such as those from a patient’s breathing and from the environment during recording in clinics. When using electrocochleaography (ECochG or ECoG), such as cochlear microphonics (CMs), acoustic background noise do not contaminate the recordings. Our objective is to study the response pattern of CM waveforms (CMWs) to explore an alternative approach in assessing cochlear functions. In response to a 14-msec tone burst across several acoustic frequencies, CMWs were recorded at the ear canal from ten normal hearing subjects. A relatively long tone burst has a relatively narrow frequency band. The CMW amplitudes among different frequencies were compared. The CMW amplitudes among different frequencies were compared. Two features were observed in the response pattern of CMWs: the amplitude of CMWs decreased with an increase of stimulus frequency of the tone bursts; and such a decrease occurred at a faster rate at lower frequencies than at higher frequencies. Five factors as potential mechanisms for these features are proposed. Clinical applications such as hearing screening are discussed. Therefore, the response pattern of CMWs suggests that they may be used as an alternative to OAEs in the assessment of cochlear functions in the clinic, especially at low frequencies. PMID:22696071

2012-01-01

206

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

NASA Astrophysics Data System (ADS)

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.

Nemeth, Richard S.; Kadison, Elizabeth

2013-12-01

207

The Use of Census Migration Data to Approximate Human Movement Patterns across Temporal Scales  

PubMed Central

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

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

2013-01-01

208

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

PubMed

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

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

2013-08-01

209

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

PubMed

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

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

2013-01-01

210

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

PubMed Central

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

Gauvin, Laetitia; Panisson, Andre; Cattuto, Ciro

2014-01-01

211

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

PubMed

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

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

2012-05-01

212

Lacustrine Groundwater Discharge at Lake Hinnensee - Spatial Patterns and their Temporal Stability  

NASA Astrophysics Data System (ADS)

Lacustrine groundwater discharge (LGD) can play an important role for the lake water balance and lake water quality of enclosed lakes. Measuring groundwater- lake interactions is generally challenging and spatial exchange patterns are seldom explored in detail. This study aims at a) identifying spatial patterns of lacustrine groundwater discharge along the shoreline of Lake Hinnensee, b) identifying spatial patterns of LGD along several cross-sections through the lake and c) investigating the temporal dynamics of these flow patterns for both the seasonal and event time scales. The lake under investigation is located in the lowlands of northeast Germany. The lake has a surface area of 49 ha and the length of the shore line is about 4 km. To monitor LGD at Lake Hinnensee short piezometer transects (2-4 piezometers) were installed every 250 m around the lake. Additional piezometers were installed where major inflow was expected. Vertical hydraulic gradients indicating strength and direction of exchange are measured continuously with pressure sensors. To identify small scale spatial variability vertical temperature profiles were measured every 10 m along 2.35 km of the total shoreline. LGD rates can be determined by fitting the heat transport equation to these profiles. Measurements were repeated in summer 2011, 2012, 2013 and winter 2013 to investigate the temporal stability of the observed patterns. It is generally assumed that the majority of groundwater inflow occurs in the immediate vicinity of the shore line (the focus area of the temperature surveys and piezometer transects). Strength of hydraulic gradients measured in the piezometers decrease considerably within the first few meters from shore und thus support the general assumption, but no information on groundwater discharge is available within the lake basin itself. To test the hypothesis of minimal off-shore groundwater inflows we installed a 500 m long distributed-temperature-sensing cable on the lake sediment resulting in several transects across the northern part of the lake. Measurements will be carried out in February when temperature differences between lake and groundwater are expected to be strongest.

Tecklenburg, Christina; Blume, Theresa

2014-05-01

213

Temporal Pattern Recognition: A Network Architecture For Multi-Sensor Fusion  

NASA Astrophysics Data System (ADS)

A self-organizing network architecture for the learning and recognition of temporal patterns is proposed. This multi-layered architecture has as its focal point a layer of multi-dimensional Gaussian classification nodes, and the learning scheme employed is based on standard statistical moving mean and moving covariance calculations. The nodes are implemented in the network architecture by using a Gaussian, rather than sigmoidal, transfer function acting on the input from numerous connections. Each connection is analogous to a separate dimension for the Gaussian function. The learning scheme is a one-pass method, eliminating the need for repetitive presentation of the teaching stimuli. The Gaussian classes developed are representative of the statistics of the teaching data and act as templates in classifying novel inputs. The input layer employs a time-based decay to develop a time-ordered representation of the input stimuli. This temporal pattern recognition architecture is used to perform multi-sensor fusion and scene analysis for ROBART II, an autonomous sentry robot employing heterogeneous and homogeneous binary (on / off) sensors. The system receives sensor packets from ROBART indicating which sensors are active. The packets from various sensors are integrated in the input layer. As time progresses these sensor outputs become ordered, allowing the system to recognize activities which are dependent, not only on the individual events which make up the activity, but also on the order in which these events occur and their relative spacing throughout time. Each Gaussian classification node, representing a learned activity as an ordered sequence of sensor outputs, calculates its activation value independently, based on the activity in the input layer. These Gaussian activation values are then used to determine which, if any, of the learned sequences are present and with what confidence. The classification system is capable of recognizing activities despite missing, extraneous or slightly out-of-order inputs. An important predictive quality is also present. This system can predict that an activity may be about to occur prior to receiving confirmation that all component events have occurred. Overall, the temporal pattern recognition system allows the robot to go beyond the alert / no alert stage based on a simple weighted count of the sensors firing. ROBART is now able to determine which activities are occurring, enabling it to intelligently act on this information.

Priebe, C. E.; Marchette, D. J.

1989-03-01

214

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

USGS Publications Warehouse

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.

Fleischer, Guy W.; TeWinkel, Leslie M.

1998-01-01

215

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

Nathan Becker, UCSB (KITP Pattern Conf 8-20-03) Spatio-temporal chaos in rotating Rayleigh-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

Ahlers, Guenter

216

Rapid generation of multiplexed cell cocultures using acoustic droplet ejection followed by aqueous two-phase exclusion patterning.  

PubMed

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

Fang, Yu; Frampton, John P; Raghavan, Shreya; Sabahi-Kaviani, Rahman; Luker, Gary; Deng, Cheri X; Takayama, Shuichi

2012-09-01

217

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

PubMed Central

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

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

2012-01-01

218

Differentiation of bacterial colonies and temporal growth patterns using hyperspectral imaging  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

219

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

NASA Astrophysics Data System (ADS)

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.

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

2013-08-01

220

Hippocampal Functional Connectivity Patterns During Spatial Working Memory Differ in Right Versus Left Temporal Lobe Epilepsy  

PubMed Central

Abstract Temporal lobe epilepsy (TLE), affecting the medial temporal lobe, is a disorder that affects not just episodic memory but also working memory (WM). However, the exact nature of hippocampal-related network activity in visuospatial WM remains unclear. To clarify this, we utilized a functional connectivity (FC) methodology to investigate hippocampal network involvement during the encoding phase of a functional magnetic resonance imaging (fMRI) visuospatial WM task in right and left TLE patients. Specifically, we assessed the relation between FC within right and left hippocampus-seeded networks, and patient performance (rate of correct responses) during the encoding phase of a block span WM task. Results revealed that both TLE groups displayed a negative relation between WM performance and FC between the left hippocampus and ipsilateral parahippocampal gyrus. We also found a positive relationship between performance and FC between the left hippocampus seed and the precuneus, in the right TLE group. Lastly, the left TLE specifically demonstrated a negative relationship between performance and FC between both hippocampi and ipsilateral cerebellar clusters. Our findings indicate that right and left TLE groups may develop different patterns of FC to implement visuospatial WM. Indeed, the present result suggests that FC provides a unique means of identifying abnormalities in brain networks, which cannot be discerned at the level of behavioral output through neuropsychological testing. More broadly, our findings demonstrate that FC methods applied to task-based fMRI provide the opportunity to define specific task-related networks. PMID:23705755

Doucet, Gaelle; Osipowicz, Karol; Sharan, Ashwini; Sperling, Michael R.

2013-01-01

221

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

PubMed

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

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

2012-07-01

222

Poincare Plots and Symbolic Dynamics Patterns of Left Ventricular Function Parameters Extracted From Echocardiographic Acoustic Quantification.  

National Technical Information Service (NTIS)

Throughout the echocardiographic acoustic quantification technique, a non-invasive estimate of left ventricular volume (VV) is obtained and acquired in real-time. An automated algorithm is applied to extract the beat-by-beat values of ventricular function...

G. D'Addio, E. G. Caiani, M. Turiel, S. Muzzupappa, A. Porta

2001-01-01

223

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

PubMed

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

Wardhaugh, Carl W

2014-11-01

224

The spatial and temporal patterns of falciparum and vivax malaria in Per?: 1994-2006  

PubMed Central

Background Malaria is the direct cause of approximately one million deaths worldwide each year, though it is both preventable and curable. Increasing the understanding of the transmission dynamics of falciparum and vivax malaria and their relationship could suggest improvements for malaria control efforts. Here the weekly number of malaria cases due to Plasmodium falciparum (1994–2006) and Plasmodium vivax (1999–2006) in Perú at different spatial scales in conjunction with associated demographic, geographic and climatological data are analysed. Methods Malaria periodicity patterns were analysed through wavelet spectral analysis, studied patterns of persistence as a function of community size and assessed spatial heterogeneity via the Lorenz curve and the summary Gini index. Results Wavelet time series analyses identified annual cycles in the incidence of both malaria species as the dominant pattern. However, significant spatial heterogeneity was observed across jungle, mountain and coastal regions with slightly higher levels of spatial heterogeneity for P. vivax than P. falciparum. While the incidence of P. falciparum has been declining in recent years across geographic regions, P. vivax incidence has remained relatively steady in jungle and mountain regions with a slight decline in coastal regions. Factors that may be contributing to this decline are discussed. The time series of both malaria species were significantly synchronized in coastal (? = 0.9, P < 0.0001) and jungle regions (? = 0.76, P < 0.0001) but not in mountain regions. Community size was significantly associated with malaria persistence due to both species in jungle regions, but not in coastal and mountain regions. Conclusion Overall, findings highlight the importance of highly refined spatial and temporal data on malaria incidence together with demographic and geographic information in improving the understanding of malaria persistence patterns associated with multiple malaria species in human populations, impact of interventions, detection of heterogeneity and generation of hypotheses. PMID:19558695

Chowell, Gerardo; Munayco, Cesar V; Escalante, Ananias A; McKenzie, F Ellis

2009-01-01

225

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

NASA Astrophysics Data System (ADS)

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.

Ibrahim, Hesham M.; Huggins, David R.

2011-07-01

226

Spatial and Temporal Variability of Zooplankton Thin Layers: The Effects of Composition and Orientation on Acoustic Detection of Layers.  

National Technical Information Service (NTIS)

Our primary long-term objective is to better understand the physical and biological mechanisms of formation and maintenance of thin layers of zooplankton. Because zooplankton can be strong sound scatterers, acoustic instruments are effective at detecting ...

A. Lavery, C. Ashjian, D. Fratantoni, M. Sutor, P. Wiebe

2006-01-01

227

Spatial and Temporal Variability of Zooplankton Thin Layers: The Effects of Composition and Orientation on Acoustic Detection of Layers.  

National Technical Information Service (NTIS)

Our primary long-term objective is to better understand the physical and biological mechanisms of formation and maintenance of thin layers of zooplankton. Because zooplankton can be strong sound scatterers, acoustic instruments are effective at detecting ...

A. Lavery, C. Ashijian, D. Fratantoni, M. Sutor, P. Wiebe

2007-01-01

228

Spatial and Temporal Variability of Zooplankton Thin Layers: The Effects of Composition and Orientation on Acoustic Detection of Layers.  

National Technical Information Service (NTIS)

Our primary long-term objective is to better understand the physical and biological mechanisms of formation and maintenance of thin layers of zooplankton. Because zooplankton can be strong sound scatterers, acoustic instruments are effective at detecting ...

A. Lavery, C. Ashjian, D. Fratantoni, M. Sutor, P. Wiebe

2008-01-01

229

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

PubMed Central

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

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

2010-01-01

230

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

PubMed Central

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

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

2013-01-01

231

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

PubMed

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

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

2013-01-01

232

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

233

Temporal patterns and sources of atmospherically deposited pesticides in Alpine Lakes of the Sierra Nevada, California, U.S.A.  

PubMed

Agricultural pesticides are being transported by air large distances to remote mountain areas and have been implicated as a cause for recent population declines of several amphibian species in such locations. Largely unmeasured, however, are the magnitude and temporal variation of pesticide concentrations in these areas, and the relationship between pesticide use and pesticide appearance in the montane environment. We addressed these topics in the southern Sierra Nevada mountains, California, by sampling water weekly or monthly from four alpine lakes from mid-June to mid-October 2003. The lakes were 46-83 km from the nearest pesticide sources in the intensively cultivated San Joaquin Valley. Four of 41 target pesticide analytes were evaluated for temporal patterns: endosulfan, propargite, dacthal, and simazine. Concentrations were very low, approximately 1 ng/L or less, at all times. The temporal patterns in concentrations differed among the four pesticides, whereas the temporal pattern for each pesticide was similar among the four lakes. For the two pesticides applied abundantly in the San Joaquin Valley during the sampling period, endosulfan and propargite, temporal variation in concentrations corresponded strikingly with application rates in the Valley with lag times of 1-2 weeks. A finer-scale analysis suggests that a large fraction of these two pesticides reaching the lakes originated in localized upwind areas within the Valley. PMID:20496891

Bradford, David F; Heithmar, Edward M; Tallent-Halsell, Nita G; Momplaisir, Georges-Marie; Rosal, Charlita G; Varner, Katrina E; Nash, Maliha S; Riddick, Lee A

2010-06-15

234

Temporal and Spatial Patterns of Ambient Endotoxin Concentrations in Fresno, California  

PubMed Central

Background Endotoxins are found in indoor dust generated by human activity and pets, in soil, and adsorbed onto the surfaces of ambient combustion particles. Endotoxin concentrations have been associated with respiratory symptoms and the risk of atopy and asthma in children. Objective We characterized the temporal and spatial variability of ambient endotoxin in Fresno/Clovis, California, located in California’s Central Valley, to identify correlates and potential predictors of ambient endotoxin concentrations in a cohort of children with asthma [Fresno Asthmatic Children’s Environment Study (FACES)]. Methods Between May 2001 and October 2004, daily ambient endotoxin and air pollutants were collected at the central ambient monitoring site of the California Air Resources Board in Fresno and, for shorter time periods, at 10 schools and indoors and outdoors at 84 residences in the community. Analyses were restricted to May–October, the dry months during which endotoxin concentrations are highest. Results Daily endotoxin concentration patterns were determined mainly by meteorologic factors, particularly the degree of air stagnation. Overall concentrations were lowest in areas distant from agricultural activities. Highest concentrations were found in areas immediately downwind from agricultural/pasture land. Among three other measured air pollutants [fine particulate matter, elemental carbon (a marker of traffic in Fresno), and coarse particulate matter (PMc)], PMc was the only pollutant correlated with endotoxin. Endotoxin, however, was the most spatially variable. Conclusions Our data support the need to evaluate the spatial/temporal variability of endotoxin concentrations, rather than relying on a few measurements made at one location, in studies of exposure and and respiratory health effects, particularly in children with asthma and other chronic respiratory diseases. PMID:20494854

Tager, Ira B.; Lurmann, Frederick W.; Haight, Thaddeus; Alcorn, Siana; Penfold, Bryan; Hammond, S. Katharine

2010-01-01

235

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

USGS Publications Warehouse

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.

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

2006-01-01

236

Temporal and spatial distribution patterns of echinoderm larvae in La Parguera, Puerto Rico.  

PubMed

This study describes temporal and spatial abundance patterns of echinoderm larvae in La Parguera, Puerto Rico. For the temporal study, larvae were sampled by a series of monthly tows taken with a 64 microm mesh net between the new and full moon from April 2005 to July 2006, September 2006 and August 2007. In order to measure spatial variation of echinoderm larval abundances, oblique tows were taken with 64 and 202 microm mesh nets at seven different sites within the shelf, at the shelf-edge, and at a nearby oceanic stations during August 2007. Overall, Echinoidea (sea urchin) exhibited the highest abundance with a total of 11 921 larvae, representing 52.5% of the total collection. Ophiuroidea (brittle star) ranked second in abundance with 45.6% of the total larvae. Holothuroidea (sea cucumber) and Asteroidea larvae (sea star) accounted for less than 2% of the total echinoderm larval collection. Early larval stages (2-8 day old) of Diadema antillarum represented 20% of the total Echinoidea larvae. There was no marked seasonal trend of echinoderm larval abundance; Echinoidea and Ophiuroidea larvae were present in all monthly samples indicating that reproduction occurs year-round. Peak abundances of later-stage Echinoidea larvae were observed during January, July and October and of later-stage Ophiuroidea larvae during June, August and October. The observed peaks of later-stage larval abundances may be indicative of higher recruitment activity during these months. There was a significant difference of echinoderm larval abundance between spatial stations, with higher abundances collected at the shelf-edge. Later-stage (approximately 24 day old) D. antillarum larvae were mostly collected at shelf-edge and oceanic locations. In addition, the 64 microm mesh net was more efficient for collection of echinoderm larvae than the 202 microm mesh net. PMID:21302410

Williams, Stacey M; Jorge, García-Sais

2010-10-01

237

Spatial and temporal patterns of sea ice variations in Vilkitsky strait, Russian High Arctic  

NASA Astrophysics Data System (ADS)

The Arctic Ocean has been greatly affected by climate change. Future predications show an even more drastic reduction of the ice cap which will open new areas for the exploration of natural resources and maritime transportation.Shipping through the Arctic Ocean via the Northern Sea Route (NSR) could save about 40% of the sailing distance from Asia (Yokohama) to Europe (Rotterdam) compared to the traditional route via the Suez Canal. Vilkitsky strait is the narrowest and northest portion of the Northern Sea Route with heaviest traffic between the Taimyr Peninsular and the Severnaya Zemlya archipelago. The preliminary results of sea ice variations are presented by using moderate-resolution imaging spectro radiometer(MODIS) data with 250-m resolution in the Vilkitsky strait during 2009-2012. Temporally, the first rupture on sea ice in Vilkitsky strait usually comes up in April and sea ice completely break into pieces in early June. The strait would be ice-free between August and late September. The frequency of ice floes grows while temperature falls down in October. There are always one or two months suitable for transport. Spatially, Sea ice on Laptev sea side breaks earlier than that of Kara sea side while sea ice in central of strait breaks earlier than in shoreside. The phenomena are directly related with the direction of sea wind and ocean current. In summmary, study on Spatial and temporal patterns in this area is significant for the NSR. An additional research issue to be tackled is to seeking the trends of ice-free duration in the context of global warming. Envisat ASAR data will also be used in this study.

Ci, T.; Cheng, X.; Hui, F.

2013-12-01

238

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

PubMed Central

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

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

2010-01-01

239

Temporal pattern and spectral complexity as stimulus parameters for eliciting a cardiac orienting reflex in human fetuses.  

PubMed

The purpose of this study was to determine whether temporal pattern and/or spectral complexity were important stimulus parameters for eliciting a cardiac orienting reflex (OR) in low-risk human fetuses. Each of 28 term fetuses was exposed to four sounds formed from the four different combinations of temporal pattern (pulsed, continuous) and spectral complexity (sine wave, /â/). The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz, and fetal R-waves were extracted by using adaptive signal-processing techniques. We found that pulsed sounds elicited a significantly greater decrease in heart rate (HR) than did continuous sounds. However, the HR response was relatively unaffected by spectral complexity. For the pure tone and the phoneme used in this study, our results indicate that temporal characteristics were more effective at eliciting a cardiac OR in human fetuses than was spectral complexity. PMID:10723210

Groome, L J; Mooney, D M; Holland, S B; Smith, Y D; Atterbury, J L; Dykman, R A

2000-02-01

240

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

E-print Network

Temporal trajectories of phosphorus and pedo-patterns mapped in Water Conservation Area 2 trajectories of soil and ecosystem properties is a daunting task that includes mapping across geographic space and through time (i.e., xyz space and the time dimension). To map change in soil nutrient status across

Grunwald, Sabine

241

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

Microsoft Academic Search

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).

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

2008-01-01

242

Spatial and Temporal Patterns of Campylobacter Contamination Underlying Public Health Risk in the Taieri River, New Zealand  

Microsoft Academic Search

during winter. However, seasonal patterns of disease can vary among regions; for example, some areas exhibit New Zealand's freshwater ecosystems are subject to microbial con- high rates of disease in both summer and winter. Hearn- tamination from a predominantly agricultural landscape. This study den et al. (2003) concluded that spatiotemporal varia- examines the spatial and temporal distribution of the human

Rebekah Eyles; Dev Niyogi; Colin Townsend; George Benwell; Philip Weinstein

243

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

Microsoft Academic Search

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

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

2008-01-01

244

Temporally patterned pulse trains affect directional sensitivity of inferior collicular neurons of the big brown bat, Eptesicus fuscus  

Microsoft Academic Search

The directional sensitivity of inferior collicular neurons of the big brown bat, Eptesicus fuscus, was studied under free field stimulation conditions with 3 temporally patterned trains of sound pulses which differed in pulse repetition rate and duration. The directional sensitivity curves of 92 neurons studied can be described as hemifield, directionally-selective, or non-directional according to the variation in the number

M. I. Wu; P. H. S. Jen

1996-01-01

245

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

Microsoft Academic Search

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

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

2005-01-01

246

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

Microsoft Academic Search

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

M. H. Conte; J. C. Weber

2010-01-01

247

Spatial and temporal patterns of pesticide use on California almonds and associated risks to the surrounding environment  

E-print Network

in revenue in 2012 (Almond Board of California, 2012). Almost all the California almond orchards (3080 km2Spatial and temporal patterns of pesticide use on California almonds and associated risks/risk in California almonds were studied. · Use intensities of insecticides/fungicides/herbicides showed latitudinal

Zhang, Minghua

248

Spatial and temporal variation in mortality of newly settled damselfish: patterns, causes and co-variation with settlement  

Microsoft Academic Search

Local abundance and dynamics of sedentary species with a dispersing life stage reflect factors that influence input and loss rates to patches of suitable habitat. For reef fishes, more attention has focused on sources of variation in input (larval settlement) than on patterns and causes of subsequent losses. We estimated spatial and temporal variation in juvenile mortality of a tropical

Sally J. Holbrook; Russell J. Schmitt

2003-01-01

249

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

ERIC Educational Resources Information Center

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…

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

2008-01-01

250

Spatial and temporal patterns in the dynamics of analogue accretionary wedges  

NASA Astrophysics Data System (ADS)

Analogue models of accretionary wedges have been studied for decades to understand the processes underlying the complexity of orogenic belts. Especially spatial and temporal varying deformation behaviour in wedge dynamics is an ongoing study. In this study we give an overview of recent experiments intended to simulate spatiotemporal deformation pattern at various time scales. We conducted experiments of two different set-ups of analogue sand models, representing the brittle upper crust. From the first set of experiments we obtain a cross section of wedge deformation in particular 1) deformation time series characterized by first order new thrusts formation and second order thrust reactivation and 2) time series of the evolution of the wedge geometry. Analysis of the data consisted of characterizing the temporal fault behaviour in relation to the growing wedge geometry. Therefore also characterizing the wedge into zones of active and inactive segments. A second set-up provided the surface expression of deformation correlated with high resolution recording of the push exerted by the growing wedge. The well correlated surface deformation and force data show varying patterns of deformation at different time scales e.g. 1) localization of strain at each thrust event, 2) between two accretionary cycle and 3) smaller scale stick - slip events. Together the two experimental approaches provide a compilation of data that aids in unravelling the transient internal deformation style of the accretionary wedge. Our study uses the Critical taper theory as the bases for understanding wedge evolution through parameters that govern the force balance. Results show that strain localization, duration of a thrust event (related to the forces applied on the fault plane) and inactivity of the thrust are feedback interactions with the geometry and load of the wedge. Force balancing of the parameters as they change in time delineates that the mechanics are controlled by processes that employ least gravitational or frictional work. Therefore changing the role and activation of first order (new fault) and second order structures (reactivation of faults). Overall, it is observed that complexity in processes of the wedge are not primarily inherit but develop due to the interaction of varying styles of deformations.

Santimano, Tasca; Rosenau, Matthias; Oncken, Onno

2014-05-01

251

Biophysical Modeling of the Temporal Niche: From First Principles to the Evolution of Activity Patterns  

E-print Network

Biophysical Modeling of the Temporal Niche: From First Principles to the Evolution of Activity://www.jstor.org #12;vol. 179, no. 6 the american naturalist june 2012 Biophysical Modeling of the Temporal Niche: From of diurnal versus noc- turnal activity using a biophysical model to evaluate the preferred temporal niche

Porter, Warren P.

252

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

NASA Technical Reports Server (NTRS)

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.

Young, Joy W.

1995-01-01

253

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

254

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

PubMed Central

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

Sakamoto, Manabu; Ruta, Marcello

2012-01-01

255

Spatial pattern and temporal dynamics of groundwater-surface water interaction in heterogeneous alluvial fan system  

NASA Astrophysics Data System (ADS)

As a key component of the hydrologic system, groundwater and surface water interaction in aquifer-aquitard complexes has not received adequate study. It has long been realized that the heterogeneity of geologic sediments strongly affects the groundwater flow and solute transport. In large scale deep heterogeneous vadose zone system, it remains numerically challenging to model the interplay between surface water and groundwater because of the highly non-linear aspect of partially saturated flow, three-dimensional heterogeneity requiring large systems of equations, and the sharp contrast in permeability between aquifer and aquitard in geologic systems. In this study, the spatial pattern of groundwater and surface water interaction and their temporal dynamics are investigated in a regional scale model (36.2 km by 45.4 km by 600 m) with high resolution (200 m by 200 m by 1 m) and detailed geo-structure with the fully parallel code, ParFlow, which solves three dimensional Richard's Equation in a fully mass conservative manner. This model makes it possible to study the groundwater dynamics, perched aquifer system, spatial pattern of surface water infiltration on a scale that is appropriate for investigating regional interplay between groundwater pumping, streamflow, and water resources management. The findings of this study will benefit large coupled hydrologic modeling, such as hydro-climate modeling, in the sense of better understanding the mechanism of feedbacks between groundwater and surface water, as well as provide strategic solutions on water resource management, especially as the climate variability drives year to year change in surface water and groundwater conjunctive usage.

Liu, Y.; Newcomb, N. J.; Fogg, G. E.

2013-12-01

256

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

PubMed

Studies focused on how prey trade-off predation and starvation risk are prevalent in behavioral ecology. However, our current understanding of these trade-offs is limited in one key respect: we know little about the behavior of predators. In this study, we provide some of the first detailed information on temporal patterns in the daily hunting behavior of bird-eating Accipiter hawks and relate that to their prey. During the winters of 1999-2004, twenty-one sharp-shinned hawks (A. striatus) and ten Cooper's hawks (A. cooperii) were intensively radio tracked in rural and urban habitats in western Indiana, USA. Cooper's hawks left roost before sunrise and usually returned to roost around sunset, while sharp-shinned hawks left roost at sunrise or later and returned to roost well before sunset. An overall measure of Cooper's-hawk-induced risk (a composite variable of attack rate and activity patterns) generally reflected the timing of prey activity, with peaks occurring around sunrise and sunset. In contrast, risk induced by the smaller sharp-shinned hawk did not strongly reflect the activity of their prey. Specifically, an early morning peak in prey activity did not correspond to a period with intense hawk activity. The lack of early morning hunting by sharp-shinned hawks may reflect the high risk of owl-induced predation experienced by these hawks. The net effect of this intraguild predation may be to "free" small birds from much hawk-induced predation risk prior to sunrise. This realization presents an alternative to energetics as an explanation for the early morning peak in small bird activity during the winter. PMID:17216210

Roth, Timothy C; Lima, Steven L

2007-05-01

257

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

PubMed

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

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

2014-07-01

258

Spatial and Temporal Patterns of Past Mountain Glaciation in the Tian Shan, Central Asia  

NASA Astrophysics Data System (ADS)

Reconstructing chronologies of past glaciation using consistent methods is critical for efforts to examine the timing and spatial patterns of past climate changes. Using remote sensing data for initial mapping of glacial landforms, combined with field investigations to refine the mapping and 10Be surface exposure dating to constrain ages, we aim to improve understanding of spatial and temporal patterns of past glaciation along the length of the Tian Shan from Kyrgyzstan to China, including valleys with both southerly and northerly aspects. Building on past work by others, we have significantly expanded the range of sites for which data are available and the number of absolute ages to constrain the glacial chronology. This includes over 60 10Be surface exposure ages from two valleys with northern (source area of the Urumqi River) and southern aspects centered on the Central Tian Shan, and three sites in the western Tian Shan of Kyrgyzstan. The records of glaciation across the Tian Shan include preservation of fewer glaciations in northerly-trending than in southerly-trending valleys, evidence for glacial advance during MIS 2 throughout the mountain range, advances during MIS 6, 4 and 3 in some southerly-trending valleys, and a Holocene record in the central Tian Shan that is dominated by an extensive LIA advance. The LIA advance presumably destroyed evidence for other Holocene advances that were less extensive than that during the LIA advance. The disparity in records between northerly- and southerly-trending valleys could reflect a difference in the number of events as a result of the difference in aspect between north and south facing valleys, and/or differential preservation.

Harbor, J.; Stroeven, A. P.; Li, Y.; Lifton, N. A.; Blomdin, R.; Beel, C. R.; Caffee, M. W.; Chen, Y.; Gribenski, N.; Hättestrand, C.; Heyman, J.; Ivanov, M.; Kassab, C.; Li, Y.; Liu, G.; Petrakov, D.; Rogozhina, I.; Usubaliev, R.; Zhang, M.

2013-12-01

259

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

260

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

NASA Astrophysics Data System (ADS)

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

Lasaponara, R.

2009-04-01

261

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

PubMed Central

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

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

2014-01-01

262

Spatio-temporal pattern analysis of urban thermal environment of different types of cities  

NASA Astrophysics Data System (ADS)

Cities with different functions show variable thermal patterns. This study directs at horizontal contrasting the heat island effect of cities and towns in the same latitude. The data source was Landsat TM, by which the thermal infrared bands is used with the algorithm of ARTIS inversion of Heilongjiang Province to acquire the surface temperature of Ha-Qi different types of cities in 1995(1989), 2006 and 2010. In this paper we analyzed the land surface temperature(LST) of temporal, spatial and regional. The results show that a high zone is mainly centralized in the old city and industrial zone. Impervious surface increase leads to temperature rise. Relatively high and low zone fluctuation is due to human activities influence. Climate is one of the key factors to affect the LST, such as precipitation and drought. Through the analysis of urban thermal environment, the process of urbanization can be monitored, to provide accurate information for the quality evaluation of urban thermal environment and heat source survey.

Liu, Yang; Liu, Huanjun; Zhang, Yuanzhi; Zhang, Xinle; Zang, Hongting; Hu, Wen

2014-03-01

263

Spatio-temporal patterns of genome evolution in allotetraploid species of the genus Oryza.  

PubMed

Despite knowledge that polyploidy is widespread and a major evolutionary force in flowering plant diversification, detailed comparative molecular studies on polyploidy have been confined to only a few species and families. The genus Oryza is composed of 23 species that are classified into ten distinct 'genome types' (six diploid and four polyploid), and is emerging as a powerful new model system to study polyploidy. Here we report the identification, sequence and comprehensive comparative annotation of eight homoeologous genomes from a single orthologous region (Adh1-Adh2) from four allopolyploid species representing each of the known Oryza genome types (BC, CD, HJ and KL). Detailed comparative phylogenomic analyses of these regions within and across species and ploidy levels provided several insights into the spatio-temporal dynamics of genome organization and evolution of this region in 'natural' polyploids of Oryza. The major findings of this study are that: (i) homoeologous genomic regions within the same nucleus experience both independent and parallel evolution, (ii) differential lineage-specific selection pressures do not occur between polyploids and their diploid progenitors, (iii) there have been no dramatic structural changes relative to the diploid ancestors, (iv) a variation in the molecular evolutionary rate exists between the two genomes in the BC complex species even though the BC and CD polyploid species appear to have arisen <2?million years ago, and (v) there are no clear distinctions in the patterns of genome evolution in the diploid versus polyploid species. PMID:20487382

Ammiraju, Jetty S S; Fan, Chuanzhu; Yu, Yeisoo; Song, Xiang; Cranston, Karen A; Pontaroli, Ana Clara; Lu, Fei; Sanyal, Abhijit; Jiang, Ning; Rambo, Teri; Currie, Jennifer; Collura, Kristi; Talag, Jayson; Bennetzen, Jeffrey L; Chen, Mingsheng; Jackson, Scott; Wing, Rod A

2010-08-01

264

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

PubMed

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

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

2014-05-27

265

The temporal patterning of tension reduction: stress and alcohol use on weekdays and weekends.  

PubMed

A sample of 328 students provided reports of drinking episodes and ratings of situational stress experienced during two series of 4-hour time blocks covering early and late evening hours on weekdays (Tuesday and Wednesday) or weekends (Friday and Saturday). Although baseline levels of "predrinking" stress were not strongly related to the onset of drinking episodes in subsequent time blocks, analyses of temporal changes in stress from "predrinking" to "drinking" blocks show a significant tension-reduction effect among respondents who used alcohol--in contrast to those who did not drink--on both weekday evenings and early Friday evening (4-8 PM). No significant changes in stress ratings occurred among late Friday or Saturday evening drinkers. Multivariate analyses indicate that the weekday tension reduction effect is not systematically contingent on questionnaire measures of individual characteristics (age, sex, coping motives and typical drinking patterns) nor on situational measures of consumption and intoxication. The results suggest that weekday drinking after work or class is a culturally defined occasion for "time out" from stress. PMID:1943096

Orcutt, J D; Harvey, L K

1991-09-01

266

Temporal Patterns in Bivalve Excurrent Flow Under Varying Ambient Flow Conditions  

NASA Astrophysics Data System (ADS)

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.

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

2008-11-01

267

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

PubMed Central

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

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

2014-01-01

268

Multi-voxel pattern analysis of noun and verb differences in ventral temporal cortex.  

PubMed

Recent evidence suggests a probabilistic relationship exists between the phonological/orthographic form of a word and its lexical-syntactic category (specifically nouns vs. verbs) such that syntactic prediction may elicit form-based estimates in sensory cortex. We tested this hypothesis by conducting multi-voxel pattern analysis (MVPA) of fMRI data from early visual cortex (EVC), left ventral temporal (VT) cortex, and a subregion of the latter - the left mid fusiform gyrus (mid FG), sometimes called the "visual word form area." Crucially, we examined only those volumes sampled when subjects were predicting, but not viewing, nouns and verbs. This allowed us to investigate prediction effects in visual areas without any bottom-up orthographic input. We found that voxels in VT and mid FG, but not in EVC, were able to classify noun-predictive trials vs. verb-predictive trials in sentence contexts, suggesting that sentence-level predictions are sufficient to generate word form-based estimates in visual areas. PMID:25156159

Boylan, Christine; Trueswell, John C; Thompson-Schill, Sharon L

2014-10-01

269

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

PubMed

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

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

270

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

PubMed Central

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

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

271

Temporal and spatial patterns of anthropogenic disturbance at McMurdo Station, Antarctica  

NASA Astrophysics Data System (ADS)

Human visitations to Antarctica have increased in recent decades, raising concerns about preserving the continent's environmental quality. To understand the spatial and temporal patterns of anthropogenic disturbances at the largest scientific station in Antarctica, McMurdo Station, a long-term monitoring program has been implemented. Results from the first nine years (1999-2007) of monitoring are reported. Most physical disturbance of land surfaces occurred prior to 1970 during initial establishment of the station. Hydrocarbons from fuel and anthropogenic metals occur in patches of tens to hundreds of square meters in areas of fuel usage and storage. Most soil contaminant concentrations are not expected to elicit biological responses. Past disposal practices have contaminated marine sediments with polychlorinated biphenyls (PCBs), petroleum hydrocarbons, and metals in close proximity to the station that often exceed concentrations expected to elicit biological responses. Chemical contamination and organic enrichment reduced marine benthic ecological integrity within a few hundred meters offshore of the station. Contaminants were detected in marine benthic organisms confirming bioavailability and uptake. PCBs in sediments are similar to suspected source materials, indicating minimal microbial degradation decades after release. Anthropogenic disturbance of the marine environment is likely to persist for decades. A number of monitoring design elements, indicators and methodologies used in temperate climates were effective and provide guidance for monitoring programs elsewhere in Antarctica.

Kennicutt, Mahlon C., II; Klein, Andrew; Montagna, Paul; Sweet, Stephen; Wade, Terry; Palmer, Terence; Sericano, Jose; Denoux, Guy

2010-07-01

272

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

PubMed Central

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

Abaid, Nicole; Porfiri, Maurizio

2010-01-01

273

Temporal patterns of genetic diversity in Kirtland's warblers (Dendroica kirtlandii), the rarest songbird in North America  

PubMed Central

Background Kirtland’s warblers are the rarest songbird species in North America, rarity due in part to a reliance on early successional Jack Pine forests. Habitat loss due to fire suppression led to population declines to fewer than 200 males during the 1970s. Subsequent conservation management has allowed the species to recover to over 1700 males by 2010. In this study, we directly examine the impact that low population sizes have had on genetic variation in Kirtland’s warblers. We compare the molecular variation of samples collected in Oscoda County, Michigan across three time periods: 1903–1912, 1929–1955 and 2008–2009. Results In a hierarchical rarified sample of 20 genes and one time period, allelic richness was highest in 1903–1912 sample (ar?=?5.96), followed by the 1929–1955 sample (ar?=?5.74), and was lowest in the 2008–2009 sample (ar?=?5.54). Heterozygosity measures were not different between the 1929–1955 and 2008–2009 samples, but were lower in the 1903–1912 sample. Under some models, a genetic bottleneck signature was present in the 1929–1955 and 2008–2009 samples but not in the 1903–1912 sample. Conclusions We suggest that these temporal genetic patterns are the result of the declining Kirtland’s warbler population compressing into available habitat and a consequence of existing at low numbers for several decades. PMID:22726952

2012-01-01

274

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

PubMed

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

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

2014-11-01

275

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

PubMed Central

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

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

276

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

277

Visual recognition based on temporal cortex cells: viewer-centred processing of pattern configuration.  

PubMed

A model of recognition is described based on cell properties in the ventral cortical stream of visual processing in the primate brain. At a critical intermediate stage in this system, 'Elaborate' feature sensitive cells respond selectively to visual features in a way that depends on size (+/- 1 octave), orientation (+/- 45 degrees) but does not depend on position within central vision (+/- 5 degrees). These features are simple conjunctions of 2-D elements (e.g. a horizontal dark area above a dark smoothly convex area). They can arise either as elements of an object's surface pattern or as a 3-D component bounded by an object's external contour. By requiring a combination of several such features without regard to their position within the central region of the visual image, 'Pattern' sensitive cells at higher levels can exhibit selectivity for complex configurations that typify objects seen under particular viewing conditions. Given that input features to such Pattern sensitive cells are specified in approximate size and orientation, initial cellular 'representations' of the visual appearance of object type (or object example) are also selective for orientation and size. At this level, sensitivity to object view (+/- 60 degrees) arises because visual features disappear as objects are rotated in perspective. Processing is thus viewer-centred and the neurones only respond to objects seen from particular viewing conditions or 'object instances'. Combined sensitivity to multiple features (conjunctions of elements) independent of their position, establishes selectivity for the configurations of object parts (from one view) because rearranged configurations of the same parts yield images lacking some of the 2-D visual features present in the normal configuration. Different neural populations appear to be selectively tuned to particular components of the same biological object (e.g. face, eyes, hands, legs), perhaps because the independent articulation of these components gives rise to correlated activity in different sets of input visual features. Generalisation over viewing conditions for a given object can be established by hierarchically pooling outputs of view-condition specific cells with pooling operations dependent on the continuity in experience across viewing conditions. Different object parts are seen together and different views are seen in succession when the observer walks around the object. The view specific coding that characterises the selectivity of cells in the temporal lobe can be seen as a natural consequence of selective experience of objects from particular vantage points. View specific coding for the face and body also has great utility in understanding complex social signals, a property that may not be feasible with object-centred processing. PMID:9755511

Perrett, D I; Oram, M W

1998-01-01

278

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

279

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

280

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

PubMed Central

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

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

2014-01-01

281

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

282

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

283

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

NASA Astrophysics Data System (ADS)

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.

Mamun, M.; Islam, M.

2012-12-01

284

Spatial and Temporal Patterns of Soil Organic Carbon in Mangrove Forest Ecosystems (Invited)  

NASA Astrophysics Data System (ADS)

Wetlands are recognized as potentially important carbon sinks, but few studies have focused on tropical and sub-tropical systems that accumulate organic carbon. Soil organic carbon (SOC) density was analyzed in multiple mangrove forests, representing 30 geographic locations and six forest types (total of 230 study plots overall). SOC density varied from 0.002 to 0.1 g cm-3, with an overall average of 0.019 and 0.058 g cm-3 in mineral and organic soils, respectively. Sites spanned a latitudinal range from 37° S to 29° N, and carbon density was correlated with average annual temperature. However, high variation in SOC density within latitude indicated additional influences. At a regional scale, SOC density varied with forest type and generally increased with hydrologic energy. At a site in Panama, SOC density varied spatially with soil pore space, which influenced bulk density and soil temperature—indicating an influence of compaction and/or degree of decomposition. Carbon sequestration rates estimated from surface accretion of organic C were similar in organic (216 g C m-2 yr-1) and mineral (145 g C m-2 yr-1) soil types, but varied across geographic locations (41 to 591 g C m-2 yr-1). Subsurface inputs of carbon, which were estimated using measured rates of root matter accumulation and root carbon content, averaged 121 g m-2 yr-1, but exceeded 400 g m-2 yr-1 at several sites. Depths of mangrove peat varied across sites from < 1 m to over 10 m, indicating the potentially large carbon stores that can develop under certain conditions. Rates of carbon accretion at a site in Belize have varied from 90 to 300 g C m-2 yr-1 over 8000 yr. These patterns indicate spatial and temporal variability in SOC and suggest multiple controls on rates of carbon accumulation in mangrove ecosystems.

McKee, K. L.

2010-12-01

285

Temporal and Geographic Patterns of Hypoglycemia among Hospitalized Patients with Diabetes Mellitus  

PubMed Central

Background Hypoglycemia is often cited as a barrier to achieving inpatient glycemic targets. We sought to characterize hypoglycemic events in our institution by work-shift cycle and by specific treatment area. Methods Capillary (bedside) and blood (laboratory) glucose values of <70 mg/dl for patients with either a known diagnosis of diabetes or with evidence of hyperglycemia were abstracted from our laboratory database for hospitalizations between October 1, 2007, and February 3, 2008. Hypoglycemic events were analyzed by 12 h nursing work-shift cycles (day shift, 07:00 to 18:59; night shift, 19:00 to 06:59) and by the six medical, surgical, and intensive care areas in the hospital (designated areas 1 to 6). Results We identified 206 individual patients with either diabetes or hyperglycemia (mean age, 67 years; 56% men; 83% white) who had 423 hypoglycemic events. There were 78% more hypoglycemic events during the night shift (n = 271 events in 128 individual patients) than during the day shift (n = 152 events in 96 individual patients). Most of the night-shift hypoglycemic measurements were detected between 04:00 and 04:59 or 06:00 and 06:59. The mean hypoglycemic level was comparable between shifts (p = .79) and across the six inpatient areas. The number of hypoglycemic events per person increased with lengths of hospital stay >5 days. The prevalence of hypoglycemia varied across patient care areas within the hospital, with most (28%) detected in one area of the hospital. Conclusion There are temporal and geographic patterns in the occurrence of hypoglycemia among patients with diabetes or hyperglycemia in our hospital. Further study should focus on the reasons underlying these variations so that specific interventions can address the risk of hypoglycemia during peak times and places. PMID:20144357

Bailon, Rachel M.; Cook, Curtiss B.; Hovan, Michael J.; Hull, Bryan P.; Seifert, Karen M.; Miller-Cage, Victoria; Beer, Karen A.; Boyle, Mary E.; Littman, Stephanie D.; Magallanez, Janice M.; Fischenich, Joanne M.; Harris, Jana K.; Scoggins, Susie S.; Uy, Josephine

2009-01-01

286

Spatial and temporal patterns of throughfall volume in a deciduous mixed-species stand  

NASA Astrophysics Data System (ADS)

SummaryThe effects of canopy structure on the spatial and temporal patterns of throughfall (TF) in deciduous mixed-species stands remains poorly documented. TF was collected on a rain event basis in an oak-beech stand, within 12 structural units of contrasting densities (low, LD; high, HD) and species composition (beech, oak, mixture) delimited by three neighbouring trees. A roof was installed at the centre of each unit, and gutters were placed at the periphery of the LD units. Based on selected rain events, a simplified mass balance approach was used to describe water fluxes reaching and leaving the canopy. During the leafed season, the proportions of incident rainfall (RF) collected as TF on the roofs steadily increased with increasing RF up to a RF volume of about 5 mm; for larger RF volumes, TF proportions stabilised around 55% under pure (LD, HD) beech and HD mixture, and around 65% under pure (LD, HD) oak and LD mixture. During the leafless period, TF proportions (on average 60%) were independent of RF but were still affected by local stand characteristics (HD mixture < HD beech < HD oak < LD beech and mixture < LD oak). At canopy saturation, lateral transfers as branch flow (BF) were substantial (35 ? (BF/RF)% ? 46) in all plots, and were significantly higher in the HD units compared to the LD plots in the leafless period; part of BF falled down as indirect TF before reaching the trunks, except in the HD units during the leafless season where stemflow and BF were similar. A mechanistic numerical model using rainfall partitioning parameters determined in this study allowed to successfully describe real-time throughfall measurements.

André, F.; Jonard, M.; Jonard, F.; Ponette, Q.

2011-03-01

287

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

288

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

PubMed Central

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 18 years old enrolled in a nation-wide, employer-provided insurance plan. All medication claims from 1999–2006 were reviewed retrospectively. Drugs were assigned to 16 broad therapeutic categories. Effects of trend over time, seasonality, age and gender on overall and within category prevalence were examined. Results: Mean monthly prevalence for dispensed medications was 23.5% (range 19.4–27.5), with highest rates in winter and lowest in July. The age group with the highest prevalence was one-year-old children. On average each month, 17.1% of all children were dispensed a single drug and 6.4% were dispensed two or more. Over time, prevalence for two or more drugs did not change, but the proportion of children dispensed a single drug decreased (slope -.02%, p?=?.001). Overall, boys had higher monthly rates than girls (average difference 0.9%, p?=?.002). However, differences by gender were greatest during middle childhood, especially for respiratory and central nervous system agents. Contraceptives accounted for a large proportion of dispensed medication to older teenage girls. Rates for the drugs with the highest prevalence in this study were moderately correlated (average Pearson r.66) with those from a previously published national survey. Conclusion: On average, nearly one quarter of a population of insured children in the United States was dispensed medication each month. This rate decreased somewhat over time, primarily because proportionally fewer children were dispensed a single medication. The rate for two or more drugs dispensed simultaneously remained steady. PMID:22829905

Olson, Karen L.; Mandl, Kenneth D.

2012-01-01

289

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

PubMed

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

Fisher, Ryan J; Wiebe, Karen L

2006-04-01

290

Spatial and Temporal Patterns of On-Road Diesel Truck Emissions in California  

NASA Astrophysics Data System (ADS)

Heavy-duty diesel-powered trucks comprise a relatively small fraction of total traffic, typically less than 10% nationally. However, as light-duty gasoline vehicle emissions have been controlled over time, diesel trucks have become a major source of emissions of pollutants such as nitrogen oxides (NOx) and fine particulate matter (PM). In the past, spatially resolved emission inventories for trucks have often been mapped either by (1) assuming a constant truck fraction and applying that value to gridded estimates of total vehicle miles traveled throughout the area of interest, or (2) using surrogates (e.g., miles of highway available in each grid square) to apportion top-down estimates of diesel emissions. Unfortunately, such simplified descriptions of truck traffic are inaccurate. Goods movement-related traffic differs markedly from passenger vehicle travel in many ways, and truck traffic does not make equal use of all available highways. Here we develop new inventories that reflect observed spatial patterns and day of week, seasonal, and decadal changes in diesel truck emissions. High-resolution (4 km) gridded emission inventories have been developed in this study for diesel trucks in California. Fuel consumption and associated CO2 emissions were calculated for each segment of highway from census counts of truck traffic that span the entire highway network. This captures the majority of truck travel and on-road diesel fuel consumption in California. Remaining truck traffic on other roadways (e.g., urban arterials) is estimated by difference using statewide taxable diesel fuel sales and fuel economy survey data. Fuel-based emission factors measured in roadside remote sensing and tunnel studies were applied to CO2 emissions to estimate NOx. Air basin-specific temporal patterns in diesel truck activity and emissions are derived from 75 Weigh-in-Motion (WIM) traffic count sites located on major highways throughout the state. WIM sensors count and classify vehicles by number of axles and weight per axle, so separate counts for truck traffic are available with hourly or better time resolution. We find strong weekly cycles in diesel truck emissions, with lower values on weekends, especially in urban air basins surrounding Los Angeles and San Francisco. We also find seasonal cycles, up to +/-20% about annual average values, in the San Francisco Bay area and the San Joaquin and Sacramento Valleys. Peak emissions in these areas occur in June-July and appear to be associated with the harvest season in Central California.

McDonald, B.; Harley, R. A.

2011-12-01

291

Temporal and spatial paleoproductivity patterns associated with Eastern Mediterranean sapropels: paleoceanographic significance.  

NASA Astrophysics Data System (ADS)

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.

Gallego-Torres, D.; Martinez-Ruiz, F.; Meyers, P. A.; Paytan, A.; Jimenez-Espejo, F. J.; Ortega-Huertas, M.

2007-12-01

292

An ontology-driven method for hierarchical mining of temporal patterns: application to HIV drug resistance research.  

PubMed

Many biomedical research databases contain time-oriented data resulting from longitudinal, time-series and time-dependent study designs, knowledge of which is not handled explicitly by most data-analytic methods. To make use of such knowledge about research data, we have developed an ontology-driven temporal mining method, called ChronoMiner. Most mining algorithms require data be inputted in a single table. ChronoMiner, in contrast, can search for interesting temporal patterns among multiple input tables and at different levels of hierarchical representation. In this paper, we present the application of our method to the discovery of temporal associations between newly arising mutations in the HIV genome and past drug regimens. We discuss the various components of ChronoMiner, including its user interface, and provide results of a study indicating the efficiency and potential value of ChronoMiner on an existing HIV drug resistance data repository. PMID:18693909

Raj, Rashmi; O'Connor, Martin J; Das, Amar K

2007-01-01

293

Analysis of Spatio-Temporal Patterns of Leaf Area Index in Different Forest Types of India Using High Temporal Remote Sensing Data  

NASA Astrophysics Data System (ADS)

Knowledge of temporal variations of Leaf Area Index (LAI) aids in understanding the climate-vegetation interaction of different vegetative systems. This information is amenable from high temporal remote sensing data. India has around 78.37 million hectare, accounting for 23.84% of the geographic area of the country under forest/tree cover. India has a diverse set of vegetation types ranging from tropical evergreen to dry deciduous. We present a detailed spatio-temporal and inter-seasonal analysis of LAI patterns in different forest types of India using MODIS 8-day composites global LAI/fPAR product for the year 2005 at 1-km spatial resolution. A forest cover mask was generated using SPOT 1-km landuse/landcover classification over the Indian region. The range of estimated LAI varied from 0.1-6.9 among the different forest types. Maximum LAI was observed in tropical evergreen forests in North-Eastern region and Western Ghats. Low LAI was observed in Central Indian region due to predominance of dry deciduous forests. The spatial patterns of seasonal variations detected that for most of the forest types, the peak LAI values were observed during September and October months of the autumn season in contrast to minimum LAI during summer season. The mean LAI and standard deviation for each 8-day LAI composite were also computed and mean monthly LAI profiles were derived for each forest type classified on the basis of their geographical locations. These results are useful indicators for detailed understanding of phenological sequence and may also serve as important inputs for deriving bioclimatic indices for different forest types of India.

Chhabra, A.; Panigrahy, S.

2011-08-01

294

Technical Acoustics, http://www.ejta.org, 2007, 17. Copyright c Technical Acoustics [ISSN 1819-2408] (2007) EEAA. Audibility of temporal smearing and time misalignment of acoustic signals  

E-print Network

. INTRODUCTION An ideal sound-reproduction chain will reproduce an ex- act replica of the original acoustic can be much shorter than 1/max. In a sound-reproduction system also, complexities in the response in audio reproduction. It has also been noted that listeners prefer higher sampling rates (e.g., 96 k

Kunchur, Milind N.

295

Acoustic emission pattern: an indicator of mode of failure in geologic materials as affected by their natural imperfections  

SciTech Connect

Two types of geologic materials, granite and coal, containing irregularities (different grain sizes and shapes in granite) and discontinuities (face and butt cleats in coal) were tested under different loading conditions. Deformation and acoustic emission characteristics of these materials under stress were recorded. In this study, for the first type of geologic material, beam specimens of approximately 4'' x 8'' x 2.5'' were prepared from four different types of granite namely, Honesboro Granite, Mason Granite, New Hampshire Pink, and Milford Pink. These were tested under constant loading rates according to the Standard Test Method for modulus of rupture of natural building stone. For the second type of geologic material, cylindrical specimens of coal were tested under a uniaxial compressive load at a constant rate of deformation. The tested coal specimens were from the Illinois number5 coal seam located in the Niantic Coal Field in southern Illinois. In both cases an MTS electrohydraulic loading system was used. Mode of failure in each material was characterized by the acoustic emission pattern and the results were substantiated by the deformation characteristics of the materials during failure.

Khair, A.W.

1984-01-01

296

Characteristics of temporal patterns of cortisol and luteinizing hormone in primiparous, postpartum, anovular, suckled, beef cows exposed acutely to bulls  

Microsoft Academic Search

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

Shaun A Tauck; Jesse R Olsen; Jarrod RC Wilkinson; Riley J Wedlake; Kathleen C Davis; James G Berardinelli

2010-01-01

297

Mapping of Conjunctive Water Use Productivity Pattern in an Irrigation Command Using Temporal IRS WiFS Data  

Microsoft Academic Search

Irrigated agriculture in many areas of the world is currently being practiced from multiple water sources such as precipitation,\\u000a canal, wetlands, ground aquifer, etc. This study highlights the use of high temporal remote sensing data [IRS-1D; Wide Field\\u000a Sensor (WiFS), 188-m resolution] to assess conjunctive water use pattern and its productivity in the 6 Main Canal command\\u000a of Damodar Irrigation

P. K. Gupta; S. Dutta; S. Panigrahy

2010-01-01

298

Spatial and temporal patterns in abundance and distribution of zooplankton in the Tanzanian waters of Lake Victoria  

Microsoft Academic Search

Zooplankton composition and abundance, and its spatial and temporal distribution patterns were investigated from September 2005 to October 2007 at 51 sampling stations at various depths in the near shore, intermediate, and offshore waters of Lake Victoria. Relative to near shore (54.86 ± 32.33 ind. l) and far offshore (38.63 ± 11.14 ind. l), the intermediate waters (109.56 ± 64.70

G. W. Ngupula; R. K. Waya; C. N. Ezekiel

2010-01-01

299

Suppression of speckle patterns based on temporal angular decorrelation induced by multiple beamlets with diverse optical paths  

NASA Astrophysics Data System (ADS)

We investigate an effective technique to alleviate the speckle contrast based on the temporal angular decorrelation induced by multiple beamlets with diverse optical paths. Multiple beamlets with diverse optical paths are generated by using a microlens array incorporating a galvo-mirror at the foci of two spherical lenses. As the multiple beamlets with different optical paths are interfered after the screen, versatile uncorrelated speckle patterns with random phases in the time domain should be induced. The random phases of the versatile uncorrelated speckle patterns can effectively suppress the speckle contrast after averaging all intensities of versatile uncorrelated speckle patterns by accumulating speckle patterns during the exposure time of the CCD camera. The speckle contrast ratios with or without the homogenizer are reduced by 10.2% and 14.2%, respectively, with a low loss of less than 5%. Evidently, the homogenizer can improve the suppression efficiency of the speckle contrast ratio.

Kim, Sunduck; Han, Young-Geun

2014-02-01

300

Cascadia Segmentation and Long Term Temporal Rupture Pattern based on Paleoseismicity: some Global Implications  

NASA Astrophysics Data System (ADS)

Onshore and offshore paleoseismic evidence from 41 Cascadia earthquakes strongly suggest that segmentation plays a significant role in Cascadia, and may have multiple sources. Offshore turbidite records show a remarkable correspondence along strike in 14C ages, physical property correlations, and even details such as mass per event and number of coarse fraction units per event. The joint correlation of these parameters allows approximate delineation of paleo-rupture extent, limited mostly by the spatial distribution of cores. The onshore-offshore space-time diagram reveals that recurrence intervals and segment length decreases southward along the margin. Southern segments may be controlled by obvious structural boundaries such as the Blanco Fracture zone, and two subducting pseudo faults. Along the northern margin, where segmentation is not apparent, basement structure is masked by thicker incoming sediment supply from two large fan systems, supporting a primary control by sediment thickness on the subducting plate. We suspect, supported by paleoseismic data, that northern Cascadia and northern Sumatra may be prone to large ruptures by similar mechanisms. One segment boundary in Cascadia appears not to be related to sediment supply, but may linked to a narrowing of the locked interface in map view. The Cascadia forearc is composed of an Eocene-Pliocene accretionary complex, outboard of which lies a Pleistocene-Holocene wedge of low taper, mixed vergence, and high pore fluid pressure. The young wedge is widest off Washington and northernmost Oregon, tapering both north and south. Mixed vergence, open folds, mud volcanoes and backstop parallel trends indicate poor coupling of the young wedge that is easily mapped from surface data. The long-term average downdip limit of significant coupling appears to be consistent with thermal, geodetic, and structural evidence of a transition from arc normal to arc parallel contraction. An average boundary consistent with these disparate data suggest significant heterogeneity in along-strike width and or magnitude of coupling. A seaward swing of the downdip locked zone, combined with a landward position of the updip limit may create a "pinchout" in central Oregon, where we observe a paleoseismic segment boundary. The 10ka paleoseismic record includes evidence of temporal variability as well. Temporal clustering, and the presence of several outsized events is apparent. When we compare the mass of correlated turbidite deposits along strike, we find a surprisingly strong correspondence between disparate sites, enough to conclude that earthquake magnitude and turbidite mass are crudely related for many Cascadia events. The two outsized events, dated at ~ 5960 and 8810 yrs. BP, consistently have two to five times the average turbidite mass for Holocene events at many sites, a relation not related to sediment supply. Plotting the long term energy balance based on mass per event reveals a robust pattern including long term increases and declines in stored "energy state" or "supercycles". If Cascadia is representative of other plate boundary faults, this suggests that recurrence models may be neither time nor slip predictable and cannot be based on short instrumental records.

Goldfinger, C.

2011-12-01

301

Complex Acoustic Pattern Learning in Songbirds and Humans Kimberly M. Fenn (kmfenn@uchicago.edu)  

E-print Network

processing without the aid of explicit training on the elements that compose the patterns. Keywords: learning; language; syntax; recursion Introduction How we acquire knowledge of linguistic patterns has been a controversial theoretical issue in research on language development. One view is that human language cannot

Gentner, Timothy

302

Analysis of the meter of acoustic musical signals  

Microsoft Academic Search

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

Anssi P. Klapuri; Antti J. Eronen; Jaakko T. Astola

2006-01-01

303

Analyzing spatial-temporal patterns of motor vehicle crashes using GIS: a case study in Dallas  

E-print Network

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...

Lu, Bing

2012-06-07

304

Spatial-temporal excess mortality patterns of the 1918-1919 influenza pandemic in Spain  

PubMed Central

Background The impact of socio-demographic factors and baseline health on the mortality burden of seasonal and pandemic influenza remains debated. Here we analyzed the spatial-temporal mortality patterns of the 1918 influenza pandemic in Spain, one of the countries of Europe that experienced the highest mortality burden. Methods We analyzed monthly death rates from respiratory diseases and all-causes across 49 provinces of Spain, including the Canary and Balearic Islands, during the period January-1915 to June-1919. We estimated the influenza-related excess death rates and risk of death relative to baseline mortality by pandemic wave and province. We then explored the association between pandemic excess mortality rates and health and socio-demographic factors, which included population size and age structure, population density, infant mortality rates, baseline death rates, and urbanization. Results Our analysis revealed high geographic heterogeneity in pandemic mortality impact. We identified 3 pandemic waves of varying timing and intensity covering the period from Jan-1918 to Jun-1919, with the highest pandemic-related excess mortality rates occurring during the months of October-November 1918 across all Spanish provinces. Cumulative excess mortality rates followed a south–north gradient after controlling for demographic factors, with the North experiencing highest excess mortality rates. A model that included latitude, population density, and the proportion of children living in provinces explained about 40% of the geographic variability in cumulative excess death rates during 1918–19, but different factors explained mortality variation in each wave. Conclusions A substantial fraction of the variability in excess mortality rates across Spanish provinces remained unexplained, which suggests that other unidentified factors such as comorbidities, climate and background immunity may have affected the 1918–19 pandemic mortality rates. Further archeo-epidemiological research should concentrate on identifying settings with combined availability of local historical mortality records and information on the prevalence of underlying risk factors, or patient-level clinical data, to further clarify the drivers of 1918 pandemic influenza mortality. PMID:24996457

2014-01-01

305

What can flux tracking teach us about water age distribution patterns and their temporal dynamics?  

NASA Astrophysics Data System (ADS)

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.

Hrachowitz, M.; Savenije, H.; Bogaard, T. A.; Tetzlaff, D.; Soulsby, C.

2013-02-01

306

From patterned optical near-fields to high symmetry acoustic vibrations in gold crystalline platelets.  

PubMed

Noble metal particles allow enhanced interaction with light and efficient light to heat conversion. In the present paper, we report on non-linear optical spectroscopy of individual gold crystalline platelets and address two of the energy relaxation steps following optical excitation of the metallic nano-objects. In particular, at short timescales we show that optical excitation yields intense two-photon photoluminescence at particular locations of the gold platelets. Our experimental results are interpreted with numerical simulations based on the Green Dyadic Method. Subsequent conversion from optical to thermal energy triggers acoustic vibrations that modulate the optical response of the nano-object on a 10 ps-100 ps timescale. We address the different contributions to the damping of the associated mechanical oscillations focusing on the high frequency thickness vibrations (100 GHz) of these nanometer-thin metallic structures. PMID:23264962

Fedou, J; Viarbitskaya, S; Marty, R; Sharma, J; Paillard, V; Dujardin, E; Arbouet, A

2013-03-28

307

River-floodplain Hydrologic Connectivity: Impact on Temporal and Spatial Floodplain Water Quality and Productivity Patterns  

NASA Astrophysics Data System (ADS)

Nutrient spiraling and cycling are critical processes for floodplain systems, but these have not been well studied in western North America. Floodplain production and function relies on the integrity of river-floodplain interactions, particularly during periods of hydrologic connectivity. The purpose of this study was to: (1) determine the importance of the timing and duration of river-floodplain hydrologic connectivity, (2) link flood event water quality to subsequent primary and secondary production, and (3) identify temporal and spatial patterns of floodplain production. The Cosumnes River watershed transports surface runoff and snowmelt from the Sierra Nevadas to the Sacramento-San Joaquin Delta. It is one of the few watersheds in California that has no major water diversions or impoundments; therefore the river responds to the natural watershed hydrology. The study site in southern Sacramento County is an unmanaged experimental floodplain, one of the few remaining floodplains in California. Weekly and flood-event water quality and macroinvertebrate sampling was conducted during the flood season from January through June in 2001 and 2002. Both water years were characterized by historically low river flows. On average, volatile suspended solids in the water column increased from 5 mg/l to 10 mg/l during early season periods of hydrologic connectivity (December - February), suggesting that during watershed flushing flood events, the river acts as a source of nutrients and organic matter to the floodplain. Following a flood event, invertebrate concentrations decreased on average from 26,000 individuals/m3 to 9,000 individuals/m3 for zooplankton and from 350 individuals/m2 to 65 individuals/m2 for benthic macro-invertebrate, suggesting a net dilution of invertebrates during flood events. Chlorophyll a (chl-a) levels were also diluted during flood events, on average from 25 ppb to 5 ppb. Zooplankton densities and chl-a levels quickly rose after flood events. On average, zooplankton densities and chl-a concentrations exceeded 150,000 individulas/m3 and 30 ppb respectively. However, as hydrologic residence time increased, chl-a levels decreased and were generally lowest following periods when macroinvertebrate population densities were highest, suggesting grazing pressure on planktonic algae. Total nitrogen to total phosphorous ratios (TN:TP) tended to be greater than 10 during periods of high hydrologic residence time, suggesting P limitation during periods of hydrologic disconnection, which coincides with the highest zooplankton densities and lowest chl-a levels observed. Following a flood event, TN:TP dramatically decreased, suggesting that during periods of river-floodplain connectivity, N tends to be the limiting nutrient. These data suggest that nutrients are replenished to the floodplain during periods of hydrologic connectivity, followed by periods of resource uptake and subsequent nutrient limitation. These patterns suggests that efforts directed towards restoration of river floodplain systems should attempt to reconstruct the naturally irregular and periodic connection cycle to enhance primary and secondary production.

Gallo, E. L.; Ahearn, D.; Dahlgren, R. A.; Grosholz, E.

2003-12-01

308

High resolution acoustic measurement system and beam pattern reconstruction method for bat echolocation emissions.  

PubMed

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

Gaudette, Jason E; Kloepper, Laura N; Warnecke, Michaela; Simmons, James A

2014-01-01

309

Separation of spatial-temporal patterns ('climatic modes') by combined analysis of really measured and generated numerically vector time series  

NASA Astrophysics Data System (ADS)

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/

Feigin, A. M.; Mukhin, D.; Volodin, E. M.; Gavrilov, A.; Loskutov, E. M.

2013-12-01

310

Sensitivity of neurons in the auditory midbrain of the grassfrog to temporal characteristics of sound. I. Stimulation with acoustic clicks.  

PubMed

The coding of fine-temporal structure of sound, especially pulse repetition rate, was investigated on the single-unit level in the auditory midbrain of the grassfrog. As stimuli periodic click trains and Poisson distributed click ensembles have been used. The response to periodic click trains was studied in two aspects, focussing on two types of possible codes: a rate code and a synchrony code. From the iso-intensity rate histogram five basic average response rate characteristics as function of pulse repetition rate have been established: low-pass, band-pass, high-pass, bimodal and non-selective unit types. The synchronization capability, expressed in a synchronization index, was for a small majority of units non-significant and a low-pass function of pulse repetition rate for most of the other units. The rate code showed the largest diversity of response types and an enhanced selectivity to pulse repetition rate. The stimulus-response relation to Poisson distributed click ensembles was investigated by a non-linear system theoretical approach. On the basis of first- and second-order Poisson kernels possible neural mechanisms accounting for temporal selectivity were determined. A considerable fraction of units exhibited response characteristics that were invariant to changes in sound pressure level and average click rate. These units may function as feature detectors of fine-temporal structure of sound. The spectro-temporal sensitivity range of the auditory midbrain of the grassfrog appeared to be broad and not particularly tuned to the ensemble of conspecific cells. PMID:3489702

Epping, W J; Eggermont, J J

1986-01-01

311

Spatial and Temporal Patterns of Nitrogen Transport in a Subtropical Urban Coastal Watershed  

NASA Astrophysics Data System (ADS)

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.

Toor, G.; Banger, K.; Inglett, P.; Stanley, C.

2010-12-01

312

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

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 ...

REN, WEI

313

Beam patterns of an underwater acoustic vector hydrophone located near a reflecting boundary  

Microsoft Academic Search

A vector hydrophone consists of two or three spatially collocated but orthogonally oriented velocity hydrophones plus an optional collocated pressure hydrophone. A vector hydrophone may form azimuth-elevation beams that are invariant with respect to the source frequencies, bandwidths and radial location (in the near field or the far field). This paper characterizes the spatial matched filter beam patterns (i.e. fixed

Hengameh Keshavarz

2004-01-01

314

Beam patterns of an underwater acoustic vector hydrophone located away from any reflecting boundary  

Microsoft Academic Search

A vector hydrophone is composed of two or three spatially collocated but orthogonally oriented velocity hydrophones plus an optional collocated pressure hydrophone. A vector hydrophone may form azimuth-elevation beams that are invariant with respect to the sources' frequencies, bandwidths and radial location (in near field as opposed to the far field). This paper characterizes the spatial matched filter beam patterns

Kainam Thomas Wong; Hoiming Chu

2002-01-01

315

Spatial and temporal patterns of porcine reproductive and respiratory syndrome virus (PRRSV) genotypes in Ontario, Canada, 2004–2007  

PubMed Central

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

2014-01-01

316

Review and comparison of temporal- and spatial-phase shift speckle pattern interferometry for 3D deformation measurement  

NASA Astrophysics Data System (ADS)

High accuracy full field three dimensional (3D) deformation measurements have always been an essential problem for the manufacturing, instrument, and aerospace industry. 3D deformations, which can be translated further into 3D strain and stress, are the key parameter for design, manufacturing and quality control. Due to the fast development of the manufacturing industry, especially in the automobile and airspace industry, rapid design and optimization concepts have already widely accepted. These concepts all require the support of rapid, high sensitive and accuracy 3D deformation measurement. Advanced optical methods are gaining widely acceptance for deformation and stain measurement by industry due to the advantages of non-contact, full-field and high measurement sensitivity. Of these methods, Electronic Speckle Pattern Interferometry (ESPI) is the most sensitive and accurate method for 3D deformation measurement in micro and sub micro-level. ESPI measures deformation by evaluating the phase difference of two recorded speckle interferograms under different loading conditions. Combined with a phase shift technique, ESPI systems can measure the 3D deformation with dozens of nanometer level sensitivity. Cataloged by phase calculation methods, ESPI systems can be divided into temporal phase shift ESPI systems and spatial phase shift ESPI system. This article provides a review and a comparison of temporal and spatial phase shift speckle pattern interferometry for 3D deformation measurement. After an overview of the fundamentals of ESPI theory, temporal phase-shift and spatial phase-shift techniques, 3D deformation measurements by the temporal phase-shift ESPI which is suited well for static measurement and by the spatial phase-shift ESPI which is particularly useful for dynamic measurement will be discussed in detail. Basic theory, brief derivation and different optical layouts for the two systems will be presented. The potentials and limitations of the both ESPI systems will be demonstrated by examples of precise and simultaneous measurement of 3D deformations under either static or dynamic loadings.

Xie, Xin; Yang, Lianxiang; Chen, Xu; Xu, Nan; Wang, Yonghong

2013-10-01

317

VISUALISING THE SPATIO-TEMPORAL PATTERNS OF MOTOR VEHICLE THEFT IN ADELAIDE, SOUTH AUSTRALIA  

Microsoft Academic Search

Abstract Motor Vehicle Theft (MVT) in Australia is as a serious problem with high social and economic costs. MVT is neither unique nor random, but rather tends to be unevenly distributed and has a spatial-temporalpattern. This study assesses and explains the spatio-temporal distribution of MVT within metropolitan Adelaide based on MVT incidences that occurred in 1999. In this exploratory spatial

Leakha M. Henry; Brett A. Bryan

2000-01-01

318

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 ...

319

All Our Troubles Seem So Far Away: Temporal Pattern to Accessible Alternatives and Retrospective Team Appraisals  

Microsoft Academic Search

Three studies tested the hypothesis that thoughts about alterna- tives become increasingly accessible over time, leading poor out- comes to feel subjectively farther away and less inevitable. This subjective temporal distance bias was obtained even though actual time since poor and good outcomes was identical. In Study 1, participants who recalled distant poor team outcomes thought of alternatives easily and

Lawrence J. Sanna; Edward C. Chang; Seth E. Carter

2004-01-01

320

On the use of sequential patterns mining as temporal features for music genre classification  

Microsoft Academic Search

Music can be viewed as a sequence of sound events. However, most of current approaches to genre classification either ignore temporal information or only capture local structures within the music under analysis. In this paper, we propose the use of a song tokenization method (which transforms the music into a sequence of units) in conjunction with a data mining technique

Jia-Min Ren; Zhi-Sheng Chen; Jyh-Shing Roger Jang

2010-01-01

321

Utilization of antiretroviral treatment in Ethiopia between February and December 2006: spatial, temporal, and demographic patterns  

Microsoft Academic Search

BACKGROUND: In 2003, the Ethiopian Ministry of Health (MOH) started to implement a national antiretroviral treatment (ART) program. Using data in the monthly HIV\\/AIDS Updates issued by the MOH, this paper examines the spatial and temporal distribution of ART on a population basis for Ethiopian towns and administrative zones and regions for the period February to December 2006. RESULTS: The

Helmut Kloos; Yibeltal Assefa; Aynalem Adugna; Mesfin Samuel Mulatu; Damen Haile Mariam

2007-01-01

322

Study on spatial and temporal mobility pattern of urban taxi services  

Microsoft Academic Search

The analysis of human behavior is the basis of understanding many social phenomena. Based on a large database of taxi billing system, this paper provides an analysis of human mobility data in an urban area of using taxi services in Shanghai. By studying the spatial temporal data of taxi services, it shows that the distribution of running time interval is

Genlang Chen; Xiaogang Jin; Jiangang Yang

2010-01-01

323

Aoristic Signatures and the Spatio-Temporal Analysis of High Volume Crime Patterns  

Microsoft Academic Search

The spatial analysis of crime and the current focus on hotspots has pushed the area of crime mapping to the fore, especially in regard to high volume offenses such as vehicle theft and burglary. Hotspots also have a temporal component, yet police recorded crime databases rarely record the actual time of offense as this is seldom known. Police crime data

Jerry H. Ratcliffe

2002-01-01

324

U.S. CANCER MORTALITY 1950-1978: A STRATEGY FOR ANALYZING SPATIAL AND TEMPORAL PATTERNS  

EPA Science Inventory

There are a number of technical and statistical problems in monitoring the temporal and spatial variation of local area death rates in the United States for evidence of systematically elevated risks. An analytic strategy is proposed to reduce one of the major statistical concerns...

325

Spatial and temporal patterns of Ambystoma tigrinum virus (ATV) prevalence in tiger salamanders Ambystoma tigrinum nebulosum  

Microsoft Academic Search

Amphibian ranaviruses have been documented as causes of mass mortality in amphib- ian populations throughout the world. The temporal and spatial dynamics of ranavirus infections when epidemics are not apparent remains unclear. To address this question, we collected tissue sam- ples from 2003 to 2006 in 4 geographically separated tiger salamander Ambystoma tigrinum nebulo- sum host populations on the Kaibab

Amy L. Greer; Jesse L. Brunner; James P. Collins

2009-01-01

326

Discovery of Temporal Patterns in Sparse Course-of-Disease Data  

E-print Network

. Peterson1 , Diane J. Cook1 , Dolores M. Peterson2 1 Department of Computer Science & Engineering University. Especially where laboratory, diagnosis, and therapy data are concerned, most of the data is temporal, i to other events are important. For diagnoses or drug therapies, the duration of an event is just

Cook, Diane J.

327

Characterizing spatial and temporal patterns of cloud cover and fog inundation for the Northern Channel islands of California  

NASA Astrophysics Data System (ADS)

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.

Rastogi, Bharat

328

Spatial and Temporal Patterns of Locally-Acquired Dengue Transmission in Northern Queensland, Australia, 1993-2012  

PubMed Central

Background Dengue has been a major public health concern in Australia since it re-emerged in Queensland in 1992–1993. We explored spatio-temporal characteristics of locally-acquired dengue cases in northern tropical Queensland, Australia during the period 1993–2012. Methods Locally-acquired notified cases of dengue were collected for northern tropical Queensland from 1993 to 2012. Descriptive spatial and temporal analyses were conducted using geographic information system tools and geostatistical techniques. Results 2,398 locally-acquired dengue cases were recorded in northern tropical Queensland during the study period. The areas affected by the dengue cases exhibited spatial and temporal variation over the study period. Notified cases of dengue occurred more frequently in autumn. Mapping of dengue by statistical local areas (census units) reveals the presence of substantial spatio-temporal variation over time and place. Statistically significant differences in dengue incidence rates among males and females (with more cases in females) (?2?=?15.17, d.f.?=?1, p<0.01). Differences were observed among age groups, but these were not statistically significant. There was a significant positive spatial autocorrelation of dengue incidence for the four sub-periods, with the Moran's I statistic ranging from 0.011 to 0.463 (p<0.01). Semi-variogram analysis and smoothed maps created from interpolation techniques indicate that the pattern of spatial autocorrelation was not homogeneous across the northern Queensland. Conclusions Tropical areas are potential high-risk areas for mosquito-borne diseases such as dengue. This study demonstrated that the locally-acquired dengue cases have exhibited a spatial and temporal variation over the past twenty years in northern tropical Queensland, Australia. Therefore, this study provides an impetus for further investigation of clusters and risk factors in these high-risk areas. PMID:24691549

Naish, Suchithra; Dale, Pat; Mackenzie, John S.; McBride, John; Mengersen, Kerrie; Tong, Shilu

2014-01-01

329

Temporal patterns and a disease forecasting model of dengue hemorrhagic fever in Jakarta based on 10 years of surveillance data.  

PubMed

This study aimed to describe the temporal patterns of dengue transmission in Jakarta from 2001 to 2010, using data from the national surveillance system. The Box-Jenkins forecasting technique was used to develop a seasonal autoregressive integrated moving average (SARIMA) model for the study period and subsequently applied to forecast DHF incidence in 2011 in Jakarta Utara, Jakarta Pusat, Jakarta Barat, and the municipalities of Jakarta Province. Dengue incidence in 2011, based on the forecasting model was predicted to increase from the previous year. PMID:23691630

Sitepu, Monika S; Kaewkungwal, Jaranit; Luplerdlop, Nathanej; Soonthornworasiri, Ngamphol; Silawan, Tassanee; Poungsombat, Supawadee; Lawpoolsri, Saranath

2013-03-01

330

Spatio-temporal patterns of urban growth in the area around Taihu Lake, China  

Microsoft Academic Search

Rapid urbanization and industrialization have been going with urban growth and pattern evolvement in relatively developed regions of China's coast. This paper presents an integrated study on the urban growth patterns of the area around Taihu Lake, China, by using Geographical Information Systems (GIS) and remote sensing. High-resolution Landsat TM data in 1985, 1995, 2000 and 2005, and socioeconomic data

Xiaosong Tu; Lijie Pu; Ming Zhu; Jun Wu

2009-01-01

331

Spatial and temporal patterns of bovine anaplasmosis as reported by Illinois veterinarians  

Microsoft Academic Search

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

L. L. Hungerford; R. D. Smith

1996-01-01

332

Acoustic Differences In The Imitation Of Prosodic Patterns In Children With Autism Spectrum Disorders  

PubMed Central

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

Diehl, Joshua John; Paul, Rhea

2011-01-01

333

Spatio-temporal pattern of viral meningitis in Michigan, 1993-2001  

NASA Astrophysics Data System (ADS)

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.

Greene, Sharon K.; Schmidt, Mark A.; Stobierski, Mary Grace; Wilson, Mark L.

2005-05-01

334

Spatial and temporal patterns in Cimex lectularius (Hemiptera: Cimicidae) reporting in Philadelphia, PA.  

PubMed

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

Mabud, Tarub S; Barbarin, Alexis M; Barbu, Corentin M; Levy, Katelyn H; Edinger, Jason; Levy, Michael Z

2014-01-01

335

Computational intelligence in biomedical imaging: multidimensional analysis of spatio-temporal patterns  

Microsoft Academic Search

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,

Axel Wismüller

2011-01-01

336

Temporal and Spatial Patterns of Bartonella Infection in Black-tailed Prairie Dogs ( Cynomys ludovicianus )  

Microsoft Academic Search

We describe the temporal dynamics and spatial distribution of Bartonella in black-tailed prairie dogs (Cynomys ludovicianus) based on a longitudinal study conducted in 20 black-tailed prairie dog (BTPD) colonies in Boulder County, CO from 2003 to\\u000a 2005. Bartonella infection was widely distributed in all colonies with an overall prevalence of 23.1%, but varied by colony from 4.8% to 42.5%\\u000a and

Ying Bai; M. Y. Kosoy; C. Ray; R. J. Brinkerhoff; S. K. Collinge

2008-01-01

337

Spatial and temporal patterns of nutrient concentration and export in the tidal Hudson River  

Microsoft Academic Search

Spatial and temporal dynamics of N and P were examined in the tidal Hudson River between 1992 and 1996. For all seasons and\\u000a at all locations in the river nutrient concentrations were generally quite high. TN averaged 60 ?M and was above 50 ?M in\\u000a 75% of samples. TP averaged 1.7 ?M and was above 1.2 ?M in 75% of

G. G. Lampman; N. F. Caraco; J. J. Cole

1999-01-01

338

Spatio-temporal Patterns of Inelastic Strain Produced by Southern California Earthquakes  

Microsoft Academic Search

We analyze spatial and temporal features of co-seismic in-elastic deformation in the southern California crust. At present we examine results associated with approximately 100,000 earthquakes occurring between 1981 and 2000, and are in the process of expanding the research to include earlier events. Locations and fault plane solutions for the earthquakes are determined using the HYPOINVERSE and FPFIT computer codes.

S. Levin; Y. Ben-Zion; J. Sheridan

2001-01-01

339

Temporal variability of remotely sensed suspended sediment and sea surface temperature patterns in Mobile Bay, Alabama  

USGS Publications Warehouse

Distribution patterns of suspended sediments and sea surface temperatures in, Mobile Bay were derived from algorithms using digital data from the visible, near infrared, and infrared channels of the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-TIROS-N satellite. Closely spaced AVHRR scenes for January 20, 24, and 29, 1982, were compared with available environmental information taken during the same period. A complex interaction between river discharge, winds, and astronomical tides controlled the distribution patterns of suspended sediments. These same variables, coupled with air temperatures, also governed the distribution patterns of sea surface temperatures. ?? 1990 Estuarine Research Federation.

Rucker, J.B.; Stumpf, R.P.; Schroeder, W.W.

1990-01-01

340

Aerial-target detection using the recursive temporal profile and spatiotemporal gradient pattern in infrared image sequences  

NASA Astrophysics Data System (ADS)

A new spatiotemporal target detection method that utilizes the recursive temporal profile (RTP) and the spatiotemporal gradient pattern (STGP) is proposed for infrared (IR) image sequence. In the IR search and tracking system, long-distance aerial targets compared with short-distance aerial targets appear to be composed of several pixels with no special shapes and their movements are slow. Considering the characteristics of aerial targets, an algorithm based on the STGP and fuzzy-set theory is proposed to detect long-distance aerial targets while the recursive temporal profile algorithm based on the temporal profile and mean estimation is proposed to detect short-distance aerial targets. In addition, the RTP and the STGP are combined to detect the aerial targets that exist at diverse distances in the IR image sequence. The performance of the proposed method is examined by using the receiver operating characteristic curve. The experiment results show that the proposed method performs better than the existing methods in terms of target detection and clutter removal.

Jung, Yun Sik; Song, Taek Lyul

2012-06-01

341

A cross-ecosystem comparison of spatial and temporal patterns of covariation in the recruitment of functionally analogous fish stocks  

NASA Astrophysics Data System (ADS)

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.

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

342

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

E-print Network

normal seasonal variation such as anomalous climate events (e.g., El Nino) or trends (e.g., global patterns involving events derived from the multi-year output of CASA, and other climate variables. Mining

Kumar, Vipin

343

Spatial and temporal patterns of rowan ( Sorbus aucuparia L.) regeneration in West Carpathian subalpine spruce forest  

Microsoft Academic Search

Non-random seed shadows are commonly seen in plant species whose seeds are dispersed by animals, in particular by birds. The\\u000a behaviour of birds can influence the spatial pattern of seed dispersal and, consequently, the entire regeneration process\\u000a of fleshy-fruited trees. This study examined regeneration patterns in a fleshy-fruited tree species, rowan (Sorbus aucuparia L.), growing in West Carpathian subalpine spruce

Magdalena ?ywiec; Mateusz Ledwo?

2008-01-01

344

[Explore the spatial and temporal patterns of water pollution in the Yincungang canal of the Lake Taihu basin, China].  

PubMed

Two high-density snap-shot samplings were conducted along the Yincungang canal, one important tributary of the Lake Tai, in April (low flow period) and June (high flow period) of 2010. Geostatistical analysis based on the river network distance was used to analyze the spatial and temporal patterns of the pollutant concentrations along the canal with an emphasis on chemical oxygen demand (COD) and total nitrogen (TN). Study results have indicated: (1) COD and TN concentrations display distinctly different spatial and temporal patterns between the low and high flow periods. COD concentration in June is lower than that in April, while TN concentration has the contrary trend. (2) COD load is relatively constant during the period between the two monitoring periods. The spatial correlation structure of COD is exponential for both April and June, and the change of COD concentration is mainly influenced by hydrological conditions. (3) Nitrogen load from agriculture increased significantly during the period between the two monitoring periods. Large amount of chaotic fertilizing by individual farmers has led to the loss of the spatial correlation among the observed TN concentrations. Hence, changes of TN concentration in June are under the dual influence of agricultural fertilizing and hydrological conditions. In the view of the complex hydrological conditions and serious water pollution in the Lake Taihu region, geostatistical analysis is potentially a useful tool for studying the characteristics of pollutant distribution and making predictions in the region. PMID:23243858

Yang, Xiao-Ying; Luo, Xing-Zhang; Zheng, Zheng; Fang, Shu-Bo

2012-09-01

345

Correlated stage- and subfield-associated hippocampal gene expression patterns in experimental and human temporal lobe epilepsy.  

PubMed

Epileptic activity evokes profound alterations of hippocampal organization and function. Genomic responses may reflect immediate consequences of excitatory stimulation as well as sustained molecular processes related to neuronal plasticity and structural remodeling. Using oligonucleotide microarrays with 8799 sequences, we determined subregional gene expression profiles in rats subjected to pilocarpine-induced epilepsy (U34A arrays, Affymetrix, Santa Clara, CA, USA; P < 0.05, twofold change, n = 3 per stage). Patterns of gene expression corresponded to distinct stages of epilepsy development. The highest number of differentially expressed genes (dentate gyrus, approx. 400 genes and CA1, approx. 700 genes) was observed 3 days after status epilepticus. The majority of up-regulated genes was associated with mechanisms of cellular stress and injury - 14 days after status epilepticus, numerous transcription factors and genes linked to cytoskeletal and synaptic reorganization were differentially expressed and, in the stage of chronic spontaneous seizures, distinct changes were observed in the transcription of genes involved in various neurotransmission pathways and between animals with low vs. high seizure frequency. A number of genes (n = 18) differentially expressed during the chronic epileptic stage showed corresponding expression patterns in hippocampal subfields of patients with pharmacoresistant temporal lobe epilepsy (n = 5 temporal lobe epilepsy patients; U133A microarrays, Affymetrix; covering 22284 human sequences). These data provide novel insights into the molecular mechanisms of epileptogenesis and seizure-associated cellular and structural remodeling of the hippocampus. PMID:14656328

Becker, Albert J; Chen, Jian; Zien, Alexander; Sochivko, Dmitry; Normann, Sabine; Schramm, Johannes; Elger, Christian E; Wiestler, Otmar D; Blümcke, Ingmar

2003-11-01

346

Patterns, Predictors, Variations, and Temporal Trends in Emergency Medical Service Hospital Prenotification for Acute Ischemic Stroke  

PubMed Central

Background— Emergency medical services (EMS) hospital prenotification of an incoming stroke patient is guideline recommended as a means of increasing the timeliness with which stroke patients are evaluated and treated. Still, data are limited with regard to national use of, variations in, and temporal trends in EMS prenotification and associated predictors of its use. Methods and Results— We examined 371 988 patients with acute ischemic stroke who were transported by EMS and enrolled in 1585 hospitals participating in Get With The Guidelines—Stroke from April 1, 2003, through March 31, 2011. Prenotification occurred in 249 197 EMS?transported patients (67.0%) and varied widely by hospital (range, 0% to 100%). Substantial variations by geographic regions and by state, ranging from 19.7% in Washington, DC, to 93.4% in Montana, also were noted. Patient factors associated with lower use of prenotification included older age, diabetes mellitus, and peripheral vascular disease. Prenotification was less likely for black patients than for white patients (adjusted odds ratio 0.94, 95% confidence interval 0.92–0.97, P<0.0001). Hospital factors associated with greater EMS prenotification use were absence of academic affiliation, higher annual volume of tissue plasminogen activator administration, and geographic location outside the Northeast. Temporal improvements in prenotification rates showed a modest general increase, from 58.0% in 2003 to 67.3% in 2011 (P temporal trend <0.0001). Conclusions— EMS hospital prenotification is guideline recommended, yet among patients transported to Get With The Guidelines—Stroke hospitals it is not provided for 1 in 3 EMS?arriving patients with acute ischemic stroke and varies substantially by hospital, state, and region. These results support the need for enhanced implementation of stroke systems of care. (J Am Heart Assoc. 2012;1:e002345 doi: 10.1161/JAHA.112.002345.) PMID:23130167

Lin, Cheryl B.; Peterson, Eric D.; Smith, Eric E.; Saver, Jeffrey L.; Liang, Li; Xian, Ying; Olson, DaiWai M.; Shah, Bimal R.; Hernandez, Adrian F.; Schwamm, Lee H.; Fonarow, Gregg C.

2012-01-01

347

Spatio-temporal malaria transmission patterns in Navrongo demographic surveillance site, northern Ghana  

PubMed Central

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

2013-01-01

348

Tree-ring width and density data around the Northern Hemisphere: Part 2, spatio-temporal variability and associated climate patterns  

Microsoft Academic Search

Patterns of summer temperature over the Northern Hemisphere, obtained from a calibration of a treering network, are presented for every year from 1600 to 1877. The network of tree-ring density chronologies is shown to exhibit spatially coherent modes of variability. These modes closely match summer half-year tempera ture variations, in terms of similar spatial patterns and similar temporal evolution during

Keith R. Briffa; Timothy J. Osborn; Fritz H. Schweingruber; Philip D. Jones; Stepan G. Shiyatov; Eugene A. Vaganov

2002-01-01

349

Spatial-temporal analysis of drink-driving patterns in Hong Kong.  

PubMed

Normally, bars and restaurants are the preferred locations for drinking. Therefore, there is concern that the roads in bar and restaurant areas could have a higher probability of drink-drivers and alcohol-related road crashes. Many studies have been conducted to model the association between drinking locations and the prevalence of drink-driving, so that cost-effective enforcement strategies can be developed to combat drink-driving. In this study, a cluster analysis approach was applied to model the spatial-temporal variation of drink-driving distribution in Hong Kong. Six spatial-temporal clusters of drink-driving distribution emerged from the data: (i) bar and restaurant area, weekend-overnight; (ii) bar and restaurant area, other timespan; (iii) urban area, weekend-overnight; (iv) urban area, other timespans; (v) rural area, weekend-overnight; and (vi) rural area, other timespans. Next, separate zero-inflated regression models were established to identify the factors contributing to the prevalence of drink-driving for each of the six recognized clusters. The results indicated that drivers in rural areas tend to consume more alcohol than those in urban areas, regardless of the time period. In addition, both seasonal variation and vehicle class were found to determine the breath alcohol concentration (BrAC) levels among drivers. PMID:23896045

Li, Y C; Sze, N N; Wong, S C

2013-10-01

350

Patterns of life in temporal data: indexing and hashing for fast and relevant data retrieval  

NASA Astrophysics Data System (ADS)

As datasets with time-series records, such as computer logs or financial transactions, grow larger, indexing solutions are needed that can efficiently filter out irrelevant records while retrieving most of relevant ones. These methods must capture essential temporal properties present in the data, and provide a scalable way to generate the index and update it as the new records are presented. Current time-series analysis and indexing methods are insufficient, because the fixed features they rely on capture only limited periodicity in time-series data and become brittle when the time-series encode heterogeneous temporal behaviors and are noisy and incomplete. New indexing solutions must not only cluster the data, but also infer the meaningful characteristics and present them to the users to improve their understanding of the data. In this paper, we develop an indexing procedure based on typical latent behaviors within the time series. Our method (1) converts the data to a quantized format, (2) learns identifying behaviors generating the data, and (3) produces an index for the time series based on these behaviors. The method is found to outperform standard approaches to time series indexing in terms of recall and precision for varying degrees of data noise.

Jacobsen, Matthew; Levchuk, Georgiy; Weston, Mark; Roberts, Jennifer

2014-05-01

351

Spatio-Temporal Changes of Lymphatic Contractility and Drainage Patterns following Lymphadenectomy in Mice  

PubMed Central

Objective To investigate the redirection of lymphatic drainage post-lymphadenectomy using non-invasive near-infrared fluorescence (NIRF) imaging, and to subsequently assess impact on metastasis. Background Cancer-acquired lymphedema arises from dysfunctional fluid transport after lymphadenectomy performed for staging and to disrupt drainage pathways for regional control of disease. However, little is known about the normal regenerative processes of the lymphatics in response to lymphadenectomy and how these responses can be accelerated, delayed, or can impact metastasis. Methods Changes in lymphatic “pumping” function and drainage patterns were non-invasively and longitudinally imaged using NIRF lymphatic imaging after popliteal lymphadenectomy in mice. In a cohort of mice, B16F10 melanoma was inoculated on the dorsal aspect of the paw 27 days after lymphadenectomy to assess how drainage patterns affect metastasis. Results NIRF imaging demonstrates that, although lymphatic function and drainage patterns change significantly in early response to popliteal lymph node (PLN) removal in mice, these changes are transient and regress dramatically due to a high regenerative capacity of the lymphatics and co-opting of collateral lymphatic pathways around the site of obstruction. Metastases followed the pattern of collateral pathways and could be detected proximal to the site of lymphadenectomy. Conclusions Both lymphatic vessel regeneration and co-opting of contralateral vessels occur following lymphadenectomy, with contractile function restored within 13 days, providing a basis for preclinical and clinical investigations to hasten lymphatic repair and restore contractile lymphatic function after surgery to prevent cancer-acquired lymphedema. Patterns of cancer metastasis after lymphadenectomy were altered, consistent with patterns of re-directed lymphatic drainage. PMID:25170770

Kwon, Sunkuk; Agollah, Germaine D.; Wu, Grace; Sevick-Muraca, Eva M.

2014-01-01

352

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

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).

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

353

Decoupled temporal patterns of evolution and ecology in two post-Paleozoic clades  

NASA Technical Reports Server (NTRS)

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.

McKinney, F. K.; Lidgard, S.; Sepkoski, J. J. Jr; Taylor, P. D.

1998-01-01

354

Temporal variation in end-member chemistry and its influence on runoff mixing patterns in a forested, Piedmont catchment  

NASA Astrophysics Data System (ADS)

Runoff mixing patterns for base flow and 42 storm events were investigated for a 3 year period (2008-2010) in a 12 ha forested catchment in the mid-Atlantic, Piedmont region of the USA. Eleven distinct runoff sources were sampled independently and included: precipitation, throughfall, stemflow, litter leachate, wetland soil water, tension soil water, shallow groundwater, groundwater seeps, hyporheic water, riparian groundwater, and deep groundwater. A rigorous end-member mixing analysis (EMMA) was implemented and all base flow, storm-flow, and end-member chemistries were evaluated in a two-dimensional mixing space. End-members enclosed stream water chemistry and displayed a systematic continuum in EMMA space. Base-flow chemistry of stream waters was similar to groundwater seeps. Storm-event runoff was attributed to contributions from surficial sources (precipitation, throughfall, stemflow, and litter leachate) on the rising limb of the discharge hydrograph that was followed by soil and shallow groundwater sources on the recession limb of the hydrograph. The shapes of the storm-event hysteresis loops (wide versus tight, linear patterns) varied with hydrologic conditions from wet, hydrologically well-connected conditions to a dry, disconnected state. Detailed temporal data on end-member chemistry allowed us to explain the changes in stream water hysteresis patterns and runoff mixing space to shifts in end-member chemistry that occurred as the catchment became hydrologically disconnected. These results highlight the need to recognize the temporal variation in end-member chemistry as a function of catchment wetness and the need to collect high-frequency data on both--stream water as well as potential runoff end-members to better characterize catchment flow paths and mixing responses.

Inamdar, Shreeram; Dhillon, Gurbir; Singh, Shatrughan; Dutta, Sudarshan; Levia, Delphis; Scott, Durelle; Mitchell, Myron; Stan, John; McHale, Patrick

2013-04-01

355

Frequent visitors to psychiatric emergency services: Staff attitudes and temporal patterns  

Microsoft Academic Search

Providing quality psychiatric emergency services is becoming more difficult as utilization rates soar, especially by individuals who are frequent visitors. To address this issue, a staff survey and analysis of admission patterns were conducted. Staff were more likely to believe that frequent visitors sought care because they had difficulty accessing alternative services, had basic needs unmet, were substance abusers, wanted

Cynthia L. Arfken; Lori Lackman Zeman; Lindsay Yeager; Edward Mischel; Alireza Amirsadri

2002-01-01

356

Diagnostic Patterns and Temporal Trends in the Evaluation of Adult Patients Hospitalized With Syncope  

Microsoft Academic Search

Background: Syncope is a common clinical problem that is often difficult and expensive to diagnose. We exam- ined diagnostic patterns and trends and use of specialty consultations in the evaluation of syncope. Methods: We retrospectively reviewed the medical rec- ords of consecutive adult patients hospitalized with the principal diagnosis of syncope (International Classifica- tion of Diseases, Ninth Revision, code 780.2)

L. A. Pires; Jangadeesh R. Ganji; Nalini Tarakeshwar; Robert Steele; Regina Jarandila; Daniel H. Solomon; Laura Van Houten; Robert J. Glynn; Lindsey Baden; Kelley Curtis; Harry Schrager; Jerry Avorn; Thomas P. Erlinger; Eliseo Guallar; Edgar R. Miller III; Rachael Stolzenberg-Solomon; Lawrence J. Appel; Pedro Redondo; Teresa Solano; Ana Bauza; Pedro Lloret; Sheila Feit; Mort Rubinstein; Ellen Remenchik; Walter M. Bortz II; William S. Nevin; Charles V. Allen; Karen Davis; Cathy Schoen; Stephen Schoenbaum

2001-01-01

357

Detecting Temporal Pattern and Cluster Changes in Social Networks: A study focusing UK  

E-print Network

by advances in technology, has increased. As such, time series analysis techniques are of increasing that in many cases a large number of patterns may be produced, and consequently the analysis of the end result significance. A time series, at its simplest, consists of a sequence of values associated with an attribute

Coenen, Frans

358

Detecting Temporal Pattern and Cluster Changes in Social Networks: A study focusing UK  

E-print Network

, time series analysis techniques are of increasing significance. A time series, at its simplest that in many cases a large number of patterns may be produced, and consequently the analysis of the end result time series to comprise several sub-series. As such, the sub-series may be compared to identify changes

Boyer, Edmond

359

Spatial and temporal patterns in the movement of Procambarus clarkii , an invasive crayfish  

Microsoft Academic Search

Introduced in Italy in the 1980s for aquaculture enterprises, the red swamp crayfish, Procambarus clarkii, has invaded many water bodies, giving rise to breeding populations that now threaten freshwater ecosystems. An understanding of the spatial behaviour of this crayfish could be the baseline for future research aimed at control and management. Following the same pattern as other freshwater decapods, P.

Francesca Gherardi; Silvia Barbaresi; Gabriele Salvi

2000-01-01

360

How Temporal and Spatial Aspects of Presenting Visualizations Affect Learning about Locomotion Patterns  

ERIC Educational Resources Information Center

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…

Imhof, Birgit; Scheiter, Katharina; Edelmann, Jorg; Gerjets, Peter

2012-01-01

361

Spatial and Temporal Patterns of Mercury Accumulation in Lacustrine Sediments Across the Laurentian Great Lakes Region  

EPA Science Inventory

Data from 103 sediment cores from the Great Lakes and inland lakes of the Great Lakes airshed were compiled to examine and provide a synthesis of patterns of historical and recent changes in mercury (Hg) deposition. Limited data from the lower Laurentian Great Lakes shows a lega...

362

Spatio-temporal patterns of pre-harvest brown rot epidemics within individual peach tree canopies  

E-print Network

spatial patterns at larger (landscape) or smaller (within-plant) scales, or across hierarchies from plants to landscapes (Moslonka-Lefebvre et al. 2010; Plantegenest et al. 2007; Vereijssen et al. 2007). Never- theless by abiotic factors such as within-tree variability in microclimate (e.g., wetness duration) or fungicide

Everhart, Sydney E.

363

Bioaccumulation Patterns and Temporal Trends of Mercury Exposure in Wisconsin Common Loons  

Microsoft Academic Search

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

Brick M. Fevold; Michael W. Meyer; Paul W. Rasmussen; Stanley A. Temple

2003-01-01

364

First results on forecasting the spatial occurrence pattern of L-band scintillation and its temporal evolution  

NASA Astrophysics Data System (ADS)

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.

Sridharan, R.; Bagiya, Mala S.; Sunda, Surendra; Choudhary, Rajkumar; Pant, Tarun K.; Jose, Lijo

2014-11-01

365

Metals in horseshoe crab eggs from Delaware Bay, USA: temporal patterns from 1993 to 2012.  

PubMed

The health of horseshoe crab (Limulus polyphemus) eggs is important not only to maintain horseshoe crab populations, but because they are a resource for higher trophic levels, such as fish and shorebirds. We examined the concentrations of arsenic, cadmium, chromium, lead, manganese, mercury, and selenium in the eggs of horseshoe crabs from Delaware Bay (between New Jersey and Delaware, USA) in 1993, 1994, 1995, 1999, 2000, and 2012 to determine if there were significant temporal changes and if levels appear to pose a health risk to the crabs themselves, or to predators that consume them. All metal levels declined in horseshoe crab eggs between 1994 and 2012, although the declines were much less consistent for lead and chromium than that for mercury and cadmium. Levels of contaminants found in these eggs are well below those known to cause adverse effects in the crabs themselves or to organisms that consume them, such as migrating shorebirds. PMID:25015345

Burger, Joanna; Tsipoura, Nellie

2014-10-01

366

Statistical sensitivity for detection of spatial and temporal patterns in rodent population densities.  

PubMed Central

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

Parmenter, C. A.; Yates, T. L.; Parmenter, R. R.; Dunnum, J. L.

1999-01-01

367

Spatio-Temporal Patterns of Beaked Whale Echolocation Signals in the North Pacific  

PubMed Central

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

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

368

Temporal pattern of questing tick Ixodes ricinus density at differing elevations in the coastal region of western Norway  

PubMed Central

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

2014-01-01

369

Multivariate pattern analysis of the human medial temporal lobe revealed representationally categorical cortex and representationally agnostic hippocampus.  

PubMed

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. © 2014 Wiley Periodicals, Inc. PMID:24976498

Huffman, Derek J; Stark, Craig E L

2014-11-01

370

Spatial-temporal change in precipitation patterns based on the cloud model across the Wei River Basin, China  

NASA Astrophysics Data System (ADS)

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.

Huang, Shengzhi; Hou, Beibei; Chang, Jianxia; Huang, Qiang; Chen, Yutong

2014-05-01

371

Temporal and spatial patterning of transgene expression by near-infrared irradiation.  

PubMed

We investigated whether near-infrared (NIR) light could be employed for patterning transgene expression in plasmonic cell constructs. Hollow gold nanoparticles with a plasmon surface band absorption peaking at ?750 nm, a wavelength within the so called "tissue optical window", were used as fillers in fibrin-based hydrogels. These composites, which efficiently transduce NIR photon energy into heat, were loaded with genetically-modified cells that harbor a heat-activated and ligand-dependent gene switch for regulating transgene expression. NIR laser irradiation in the presence of ligand triggered 3-dimensional patterns of transgene expression faithfully matching the illuminated areas of plasmonic cell constructs. This non-invasive technology was proven useful for remotely controlling in vivo the spatiotemporal bioavailability of transgenic vascular endothelial growth factor. The combination of spatial control by means of NIR irradiation along with safe and timed transgene induction presents a high application potential for engineering tissues in regenerative medicine scenarios. PMID:24957294

Martin-Saavedra, Francisco M; Cebrian, Virginia; Gomez, Leyre; Lopez, Daniel; Arruebo, Manuel; Wilson, Christopher G; Franceschi, Renny T; Voellmy, Richard; Santamaria, Jesus; Vilaboa, Nuria

2014-09-01

372

Properties of rice soils affecting methane production potentials: 1. Temporal patterns and diagnostic procedures  

Microsoft Academic Search

Thirty-one rice soils from different locations in the Philippines were incubated anaerobically for 100 d to determine methane (CH4) production potentials and to establish relationships between physico-chemical properties of soil and CH4 production potential. These soils showed pronounced variations in pattern and magnitude of CH4 production. Total CH4 production over 100 d incubation ranged from 163 to 837 µg CH4

Sudip Mitra; Reiner Wassmann; Mahesh C. Jain; Himanshu Pathak

2002-01-01

373

Short term spatial — temporal distribution patterns of zooplankton in Admiralty Bay (Antarctica)  

Microsoft Academic Search

The present work analyses the abundance and species composition of mesozooplankton in relation to different patterns of wind speed and tides in Admiralty Bay. The plankton was sampled on 12, 13 and 15 March 1989 with a 385 µm mesh size conical-cylindrical net by R.V. “Barão de Teffé”. In Martel Inlet, the zooplankton standing stock reached 25,223 individuals 100 m-3

A. S. Freire; M. J. C. Coelho; S. L. C. Bonecker

1993-01-01

374

Spatial and temporal patterns in the energy potential of surface water in Sweden  

NASA Astrophysics Data System (ADS)

Recent investigations show that land-use changes and hydropower regulation has caused significant changes in the annual runoff periodicity in Swedish rivers during the 20th century. Those changes in the annual periodicities are caused by structural alterations in river basins affected by intense agriculture and hydropower regulation. In addition, we found significant long-term (decadal) fluctuation in the available energy potential of surface runoff of Sweden, which has a significant impact on the planning of hydropower regulation and watershed management plans. Based on daily precipitation data in the period 1961 - 2005 we simulated using the HBV model the surface water runoff and the associated energy potential in 1001 watersheds covering the entire surface of Sweden. Comparisons were made with individual time-series of river discharge dating as far back as to the 1850s. As an average for the entire surface of Sweden, the five-year running mean of the energy potential of surface water varies between 115 TWh / year up to nearly 180 TWh / year with significant fluctuations on different periods extending up to at least 10 years. The 30-year running mean of the discharge of River Dalälven shows a decrease from 360 m3/s in the mid 19th century to 290 m3/s in 1965 and, thereafter, a significant increase. The more than century-long discharge time-series also shows decadal fluctuations that are well correlated with the fluctuations noted over the entire surface of Sweden. The fluctuations of energy potential show coherence up to 30 - 40% with the North Atlantic Oscillation index. The handling of these significant temporal variations in energy levels for hydropower purposes depends on the spatial coherence of river discharges. Consequently, we analysed the coherence spectrum of major rivers and found for the most separated rivers in Sweden that the coherence approaches asymptotically about 20 - 25 % for long-term variations. Neighbouring river basins could have coherence spectra starting at just few percents for weekly periods and increasing to over 90% for annual periods. The low coherences in river discharge on the national spatial scale is an important 'asset' for dealing with the significant temporal fluctuations in energy potential within hydropower production.

Worman, A. L.; Bottacin-Busolin, A.; Lindstrom, G.

2013-12-01

375

A network that performs brute-force conversion of a temporal sequence to a spatial pattern: relevance to odor recognition  

PubMed Central

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

Sanders, Honi; Kolterman, Brian E.; Shusterman, Roman; Rinberg, Dmitry; Koulakov, Alexei; Lisman, John

2014-01-01

376

The Spatio-Temporal Distribution Patterns of Biting Midges of the Genus Culicoides in Salta Province, Argentina  

PubMed Central

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

Aybar, Cecilia A. Veggiani; Juri, María J. Dantur; Santana, Mirta; de Grosso, Mercedes S. Lizarralde; Spinelli, Gustavo R.

2012-01-01

377

Modeling self-organized spatio-temporal patterns of PIP3 and PTEN during spontaneous cell polarization  

NASA Astrophysics Data System (ADS)

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.

Knoch, Fabian; Tarantola, Marco; Bodenschatz, Eberhard; Rappel, Wouter-Jan

2014-08-01

378

Patterns in the Composition of Microbial Communities from a Subtropical River: Effects of Environmental, Spatial and Temporal Factors  

PubMed Central

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

Liu, Lemian; Yang, Jun; Yu, Xiaoqing; Chen, Guangjie; Yu, Zheng

2013-01-01

379

Temporal lobe sulcal pattern and the bony impressions in the middle cranial fossa: the case of the el sidrón (Spain) neandertal sample.  

PubMed

Correspondence between temporal lobe sulcal pattern and bony impressions on the middle cranial fossae (MCF) was analyzed. MCF bone remains (SD-359, SD-315, and SD-1219) from the El Sidrón (Spain) neandertal site are analyzed in this context. Direct comparison of the soft and hard tissues from the same individual was studied by means of: 1) dissection of two human heads; 2) optic (white light) surface scans; 3) computed tomography and magnetic resonance of the same head. The inferior temporal sulcus and gyrus are the features most strongly influencing MCF bone surface. The Superior temporal sulcus and middle temporal and fusiform gyri also leave imprints. Temporal lobe form differs between Homo sapiens and neandertals. A wider and larger post-arcuate fossa (posterior limit of Brodmann area 20 and the anterior portion of area 37) is present in modern humans as compared to neandertals. However other traits of the MCF surface are similar in these two large-brained human groups. A conspicuous variation is appreciated in the more vertical location of the inferior temporal gyrus in H. sapiens. In parallel, structures of the lower surface of the temporal lobe are more sagittally orientated. Grooves accommodating the fusiform and the lower temporal sulci become grossly parallel to the temporal squama. These differences can be understood within the context of a supero-lateral deployment of the lobe in H. sapiens, a pattern previously identified (Bastir et al., Nat Commun 2 (2011) 588-595). Regarding dural sinus pattern, a higher incidence of petrosquamous sinus is detected in neandertal samples. Anat Rec, 297:2331-2341, 2014. © 2014 Wiley Periodicals, Inc. PMID:24943273

Rosas, Antonio; Peña-Melián, Angel; García-Tabernero, Antonio; Bastir, Markus; De La Rasilla, Marco

2014-12-01

380

Streamflow droughts in the Iberian Peninsula between 1945 and 2005: spatial and temporal patterns  

NASA Astrophysics Data System (ADS)

In this study we analyzed the spatiotemporal variability of streamflow droughts in the Iberian Peninsula from 1945 to 2005. Streamflow series belonging to 187 homogeneously distributed gauging stations across the study area were used to develop a standardized streamflow index (SSI), which facilitated comparison among regimes and basins, regardless of streamflow magnitudes. A principal component analysis was performed to identify homogeneous hydrological regions having common features based on the temporal evolution of streamflows. Identification of drought events was carried out using a threshold level approach. We assessed the duration and magnitude of drought episodes and the changes that occurred between two contrasting periods for each hydrological region. The results showed a trend toward increased drought severity in the majority of regions. Drought duration, magnitude and spatial coverage were found to depend mainly on climatic conditions and the water storage strategies in each basin. In some basins these strategies have altered river regimes, and in others created a high level of dependence on storage and water transfer rates.

Lorenzo-Lacruz, J.; Morán-Tejeda, E.; Vicente-Serrano, S. M.; López-Moreno, J. I.

2013-01-01

381

Phytoplankton blooms in the Ross Sea, Antarctica: Interannual variability in magnitude, temporal patterns, and composition  

NASA Astrophysics Data System (ADS)

The continental shelf of the Ross Sea, Antarctica, is a unique region within the Southern Ocean. Phytoplankton growth is believed to be seasonally limited, first in austral spring by irradiance, and then in summer by biologically available iron. It also is historically known to have taxonomically distinct regimes: the south-central portion is dominated by Phaeocystis antarctica and to the west diatoms are abundant. We measured photochemical yield to interpret the health of the phytoplankton assemblage from 2001-2004 and interfaced these measurements with satellite remote sensing of pigments. The bloom of 2001-2002 was similar in both temporal and spatial distributions to the climatological mean of the Ross Sea, with a peak in biomass being observed in mid-December within the Ross Sea polynyas; Fv/Fm values averaged 0.43. We found high (0.50-0.65) Fv/Fm for most of the seasonal phytoplankton bloom for 2002-2003, suggesting that it was not seasonally iron limited. An unusual, large bloom occurred during 2003-2004, with an initial bloom of P. antarctica during austral spring followed by an extensive diatom bloom in summer that may have been enhanced by an intrusion of modified circumpolar deep water. On the basis of an analysis of the historical SeaWiFS records, accumulation of phytoplankton biomass in February may occur approximately every 2-4 years, potentially being a significant source of carbon on the continental shelf.

Peloquin, Jill A.; Smith, Walker O.

2007-08-01

382

Macroinvertebrates Associated With Dikes in the Mississippi River: Spatial and Temporal Patterns  

NASA Astrophysics Data System (ADS)

Fine sediments and rocky substrates are dominant benthic macroinvertebrate habitats in the Mississippi River. We sampled macroinvertebrates in fine sediments downstream of wing dikes on four occasions and on rocks upstream of wing dikes on two occasions. We identified 65 taxa in the fine sediments and 50 taxa on the rocks, with only 26 taxa found in both habitats. Presumably, assemblage differences reflect flow and substrate differences. Assemblages in both habitats exhibited considerable temporal variability. Macroinvertebrate densities in the fine sediments ranged from 3737 to 8706 individuals m-2 y-1, with oligochaetes representing 77-92% of total density. Macroinvertebrate density on the rocks ranged from 57,770 to 162,966 individuals m-2 y-1, with hydropsychid caddisflies (Hydropsyche bidens/orris and Potamyia flava) representing 82-97% of total density. A literature survey found that macroinvertebrate assemblages in large rivers of the Mississippi River Basin (e.g., Upper and Lower Mississippi, Illinois, Ohio, and Missouri Rivers) tend to be dominated by a few taxa. Because of this, we believe that traditional approaches to describing community structure (e.g., species richness, relative abundance) in biological assessments may be insensitive to subtle differences among large river faunas.

Battle, J.; Jackson, J. K.; Sweeney, B. W.

2005-05-01

383

Climatic and geographic temporal patterns of pain in the Multicenter Study of Hydroxyurea.  

PubMed

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

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

384

Daily Temporal Patterns of Heroin and Cocaine Use and Craving: Relationship with Business Hours Regardless of Actual Employment Status  

PubMed Central

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

Phillips, Karran A.; Epstein, David H.; Preston, Kenzie L.

2013-01-01

385

Daily temporal patterns of heroin and cocaine use and craving: relationship with business hours regardless of actual employment status.  

PubMed

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

Phillips, Karran A; Epstein, David H; Preston, Kenzie L

2013-10-01

386

Spatial and temporal patterns of pesticide use on California almonds and associated risks to the surrounding environment.  

PubMed

Various stakeholders of California almonds have been investing efforts into mitigating pesticide impacts on human and ecosystem health. This study is the first comprehensive evaluation that examines the spatial and temporal patterns of pesticide use and associated environmental risks. The pesticide use data from 1996 to 2010 were obtained from the Pesticide Use Reporting database. The Pesticide Use Risk Evaluation indicator was employed to evaluate the pesticide environmental risks based on the pesticide properties and local environmental conditions. Analyses showed that the use intensities (UI) of insecticides (oils accounted for 86% of the total insecticide UI) and herbicides both increased from north to south; fungicides showed the opposite spatial pattern; and fumigants were used most intensively in the middle region. The UI of fungicides and herbicides significantly decreased and increased, respectively, throughout the study area. The insecticide UI significantly decreased in the north but increased in many areas in the south. In particular, the organophosphate UI significantly decreased across the study area, while the pyrethroid UI significantly increased in the south. The fumigant UI did not show a trend. The regional risk intensities of surface water (RIW), soil (RIS), and air (RIA) all increased from north to south, while the groundwater regional risk intensity (RIG) decreased from north to south. The main trends of RIW, RIG, and RIS were decreasing, while the RIA did not show a trend in any region. It's noticeable that although the herbicide UI significantly increased, the UI of high-leaching herbicides significantly decreased, which led to the significant decrease of RIG. In summary, the temporal trends of the pesticide use and risks indicate that the California almond growers are making considerable progress towards sustainable pest management via integrated pest management, but still require more efforts to curb the fast increase of herbicide use. PMID:24316216

Zhan, Yu; Zhang, Minghua

2014-02-15